electronics
MOI1T01
Project status and R&D efforts for Super Tau-Charm Facility
14
The Super Tau-Charm Facility (STCF) was proposed as a third-generation circular electron-positron collider in the energy range of 2-7 GeV (CoM) and with a luminosity greater than 5*10^34 cm^-2s^-1 @4 GeV, aiming to explore charm physics and tau physics in the next decades. This presentation will introduce the facility design and R&D efforts for STCF, including the design goal, accelerator and detector schemes, and key technological R&D efforts, with focus on the accelerator. Under the financial support of the key technology R&D project by the local governments and other national funding agencies, the STCF accelerator team including international collaborators has completed the conceptual design of the accelerator, and started the technical design. The accelerator consists of a full-energy injector consisting of multi-section linacs and a positron accumulator ring and a double-ring collider with the crab-waist collision scheme. Key physics and technological challenges will be addressed. Ongoing R&D efforts and progresses will be summarized. The project planning will also be given. International collaboration is much welcome.
Paper: MOI1T01
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOI1T01
About: Received: 12 May 2026 — Revised: 21 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
MOO1T02
The Ghost Collider: an innovative Higgs Factory
28
The Ghost Collider is a proposal for a 550 GeV center-of-mass (275 GeV per beam) linear collider with four interaction regions, each with the design luminosity. The primary innovation is the use of “ghost bunches” containing equal numbers of electrons and positrons, therefore being electrically neutral. In the linacs, energy is transferred between electrons and positrons in the same bunch, decelerating one type of particle and using the energy to accelerate the other; a new class of Energy Recovery Linac. At the interaction points (IPs), collisions between two neutral ghost bunches occur. Historically this approach has been referred to as "charge compensation of beam-beam". To avoid instabilities, round beams with small disruption parameter are arranged at the IPs, ensuring particles and their energy can be recycled with minimal loss. Four “serial IPs” are incorporated, where chromatic errors produced in one IP are canceled in the following IP. All interaction points have the nominal luminosity per IP of $2.8 \times 10^{34}$ cm$^{-2}$ s$^{-1}$ for a facility luminosity of $11 \times 10^{34}$ cm$^{-2}$ s$^{-1}$ @ 100 MW total electrical power for SR replacement, linac RF, cryogenic and damping ring systems. The result is a totally original concept for an electron-positron collider.
Paper: MOO1T02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOO1T02
About: Received: 15 May 2026 — Revised: 15 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
MOP1006
Study and mitigation of radiation effects in the LHCb underground areas
76
During the 2024 and 2025 LHC proton-proton runs, the LHCb experiment, following its upgrade, achieved a substantial increase in delivered luminosity compared to previous years, exceeding the level of 10 fb-1 per year. While this enhancement greatly expands LHCb’s physics reach, it also leads to a marked rise in radiation levels in the experimental insertion region, originally designed for a significantly lower luminosity target. Throughout the 2024 p-p operation, several failures of electronic racks and cryogenic sensors, mostly attributed to single-event effects (SEEs), were observed around the LHCb cavern and caused tens of hours of LHC downtime. This work presents a benchmarking of dedicated FLUKA simulations, used to quantify the radiation levels and identify possible mitigation measures, against measurements by the Battery Radiation Monitors (BatMons). The study guided the relocation of sensitive equipment and the installation of additional shielding in specific underground areas hosting critical electronics, effectively reducing radiation exposure during the remainder of Run-3. Finally, possible improvements for shielding are also discussed in view of Run-4.
Paper: MOP1006
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1006
About: Received: 13 May 2026 — Revised: 15 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP1014
Radiation environment in the FCC-ee arcs caused by synchrotron photon emission
80
In a high-energy lepton collider such as the Future Circular Collider (FCC-ee) at CERN, several phenomena create a challenging radiation environment for accelerator components and equipment including cables and electronics. This paper examines synchrotron radiation (SR), dominating at the highest beam energies (ttbar) for two different optics schemes. Recent developments in the design of photon stoppers and dedicated radiation shielding are presented, highlighting progress towards a more realistic configuration while maintaining acceptable annual ionizing dose levels. The study covers the contribution of the collider ring and the impact on the attached alcoves, housing radiation sensitive equipment. The absorbed power in accelerator components and the surrounding tunnel environment is evaluated for various operation modes to ensure compliance with the thermal load limits of the ventilation system. Furthermore, radiation and particle fluence levels dominated by photo-neutron production are quantified for the electronics bunkers located below the beamline. These results are used to assess the feasibility of employing radiation-tolerant, commercial-off-the-shelf electronics in these areas.
Paper: MOP1014
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1014
About: Received: 07 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
MOP1044
Neutrino fluence estimates for forward experiments at a 10 TeV muon collider
161
Intense and highly collimated neutrino beams are intrinsic by-products of muon decays in a high-energy muon collider. The large boost of the primary muons confines the emitted neutrinos within angular spreads of order ($10^{-5}$ rad), resulting in fluxes far exceeding those achievable in conventional neutrino facilities. Their unique properties also open opportunities for high-energy neutrino physics. In this work, the neutrino beams produced near the interaction point are characterised in terms of their spatial and energy distributions, with emphasis on their potential use for dedicated neutrino detectors. The neutrino fluence is evaluated as a function of distance from the interaction point for representative detector acceptances. At short distances, larger acceptances intercept nearly the entire neutrino core, leading to fluence saturation, while at kilometre scales different acceptances yield comparable values as beam divergence becomes significant. These results demonstrate the strong collimation and intensity of muon-collider neutrino beams and support their potential use in high-precision, high-energy neutrino studies.
Paper: MOP1044
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1044
About: Received: 07 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
MOP1075
Experimental Study of Charging and Mobilisation of Dust Grains on Beam Screen Surfaces
237
Beam losses caused by interactions between the circulating beam and dust grains have been observed at many particle accelerators, leading to premature beam dumps, quenches of superconducting magnets, and vacuum pressure bursts. At some facilities, these events have a significant impact on the overall accelerator performance. The mechanisms by which dust grains detach from vacuum-chamber surfaces and enter the beam are not yet fully understood; one possible process is charge build-up on the grain followed by lofting due to the beam potential. We present an experimental study of the charging and mobilisation of silica dust on accelerator-relevant surfaces: Cu, co-laminated Cu, laser-treated Cu, NEG-coated substrates and samples treated with VacSeal, a silicone-based resin widely used to seal vacuum leaks. The observations provide input for dust-dynamics simulations and studies of beam losses.
Paper: MOP1075
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1075
About: Received: 11 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
MOP1108
First results on fast Ion instability in the FCC-ee injector complex damping ring
300
The FCC-ee injector complex includes a dedicated damping ring planned to operate at 2.86 GeV energy to reduce the emittance of the incoming electron and positron beams prior to their injection into the high-energy linac, where they will be accelerated up to 20 GeV for the main booster ring. Ionization of the residual gas caused by interacting with the circulating bunches may occur, and these ions can be trapped and accumulated by the fields of the electron beam. This process may lead to fast beam–ion instabilities, potentially affecting beam quality in the damping ring. This study investigates the mechanisms of ion creation, accumulation and trapping across the considered FCC-ee damping-ring lattice options. A range of vacuum conditions, gas compositions and bunch parameters are explored to identify the operational regimes in which fast ion instabilities may become significant.
Paper: MOP1108
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1108
About: Received: 13 May 2026 — Revised: 15 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP1302
Status of the rapid cycling synchrotron optics
334
The spin-preserving Rapid Cycling Synchrotron (RCS) is an integral component of the Electron-Ion Collider (EIC) complex. It will accelerate 750 MeV electrons from the Beam Accumulator Ring (BAR) to 5, 9, or 18 GeV, as required by the Electron Storage Ring (ESR), all while preserving the polarization. We discuss here the design considerations and the current optics solution, including considerations related to dynamic aperture and spin preservation as well as a reduced-cost RCS for operations to 9 GeV.
Paper: MOP1302
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1302
About: Received: 13 May 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP1303
Update on injection optics into the Electron Ion Collider Hadron Storage Ring
338
The Electron Ion Collider Hadron Storage Ring (HSR) will be built on the campus of Brookhaven National Laboratory. The injection into the HSR will be vastly different from what is currently performed in the Relativistic Heavy Ion Collider. This paper will highlight the differences from RHIC, present the injection optics, and layout of the current design.
Paper: MOP1303
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1303
About: Received: 15 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
MOP6302
APS-RAG: A domain-aware hybrid retrieval augmented generation system for accelerator operations and knowledge synthesis
345
Effective knowledge management is essential to minimize downtime and maintain institutional memory in large-scale accelerator facilities. We present APS-RAG, a domain-aware Retrieval-Augmented Generation (RAG)\* system currently deployed at the Advanced Photon Source (APS), designed to synthesize operational intelligence and facilitate semantic data retrieval from various dispersed databases. The system consolidates over 10,000 unique documents from four live databases: the BELY scientific electronic logbook, operational Microsoft Teams chat, the Integrated Content Management System (ICMS), and Work Request system. By employing the latest frontier LLMs via Argonne’s ARGO AI platform, APS-RAG integrates a specialized query preprocessing pipeline that performs temporal parsing, domain acronym resolution, multi-query expansion, and final response generation. To ensure high precision, a hybrid retrieval architecture is utilized, combining dense vector and keyword search. The results are aggregated using Reciprocal Rank Fusion (RRF) and refined through cross-encoder reranking to maximize relevance\*\*. An 100-question evaluation dataset was built using InPars methodology\*\*\*, supplemented with qualitative user feedback. The final responses from APS RAG have inline citations embedded which displays the source document chunk and a web accessible link to the original document. Future developments include multimodal integration and agentic knowledge graph capabilities\*\*\*\*.
Paper: MOP6302
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6302
About: Received: 13 May 2026 — Revised: 15 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP6307
Online tuning of the NSLS-II injector using Bayesian optimization with different packages
352
The injector of the NSLS-II consists of a linear accelerator (LINAC) that accelerates the electron beam to 170 MeV, followed by a linac-to-booster (LTB) transport line and a booster synchrotron that further increases the beam energy to 3 GeV. The performance of LINAC and LTB is critical to achieve efficient and stable beam injection. Automated online tuning is an effective method to improve injector performance. In this paper, we present an automated tuning approach based on Bayesian optimization, using different software packages to optimize the LINAC and LTB. We evaluate and compare these packages based on their ability to improve injection efficiency. Our results demonstrate that Bayesian optimization can significantly enhance injector performance and show differences in performance between different packages.
Paper: MOP6307
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6307
About: Received: 13 May 2026 — Revised: 17 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
MOP6338
Beam-Based Characterisation of BPM Electronics Thermal Sensitivity after Two Decades of Operation
396
Beam-based measurements of the thermal sensitivity of beam position monitor (BPM) electronics were performed in SPEAR a third-generation storage ring after more than twenty years of routine user operations. Controlled building-temperature excursions were applied to two equipment buildings containing key BPM front-end and digitiser racks. Using orbit- and charge-normalised BPM signals and independent temperature logging, we performed lag-aware regression to estimate effective position-versus-temperature coefficients for each BPM, and compared several alternative temperature-driver models (global, per-building and hybrid). The method was applied to two measurement campaigns, months apart, with different ambient conditions. The results show clearly distinguishable building-level responses and reproducible patterns within subsets of BPMs, but also highlight strong correlations between temperature, beam conditions and slowly varying lattice effects. We present this analysis framework as a step towards robust, beam-based thermal characterisation of ageing BPM systems, and outline how extended datasets could support future BPM upgrades, thermal monitoring and operational orbit-stability tools.
Paper: MOP6338
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6338
About: Received: 13 May 2026 — Revised: 15 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP6344
XBPM calibration and simulations at SIRIUS
399
The set of X-ray Beam Position Monitors (XBPMs) at SIRIUS, the Brazilian Synchrotron Light Laboratory (LNLS), is not yet fully operational due to ongoing calibration challenges. These SIRIUS XBPMs employ a blade-type design, which exhibits a linear response only in its central region. Minor asymmetries in device construction and variations in individual blade gains can amplify distortions in the calculated beam position derived from the photocurrents generated by X-ray incidence. Standard correction methods involve applying a linear transformation to the signals, calibrated by analyzing blade behavior along central-symmetry lines. To enhance accuracy, we have extended these corrections by optimizing the transformation matrix using a simulated annealing algorithm. Furthermore, to deepen our understanding of the relationship between incident X-ray distribution and blade geometry, we developed a simulation algorithm. This tool models the blades' response to radiation, calculating the apparent beam position for various configurations of blade angles, inter-blade distances, and electronic gains. The simulation accepts a range of input beam profiles—including two-dimensional Gaussian distributions or outputs from radiation transport simulators—and can apply transformations such as stretching and rotation to these profiles.
Paper: MOP6344
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6344
About: Received: 13 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
MOP6348
Beam-induced heating and thermal analysis for the EIC HSR cryogenic helical magnet and BPM assembly
403
The EIC Hadron Storage Ring (HSR) reuses the RHIC yellow ring with substantial reconfiguration. A major challenge is mitigating beam-induced heating of cryogenic components caused by the shorter hadron bunches and an average beam current three times that of RHIC. In addition, large transverse beam offsets at injection due to helical magnet itself generate asymmetric resistive-wall losses in the cryogenic BPM region. To limit these losses, the HSR helical magnet assembly uses a new copper-plated stainless-steel beam pipe with an amorphous-carbon coating. This paper presents heating and thermal analysis of the EIC HSR cryogenic helical magnet and BPM assembly. Thermal simulations show narrow thermal margin for the helical magnet unit, and adequate margin for the BPM assembly.
Paper: MOP6348
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6348
About: Received: 18 May 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
MOP6355
Selection of transverse diagnostics to measure few-micron beam modulations in the nanopatterned microbunching experiment
411
A nanopatterned microbunching collaboration has been formed to test the production of electron microbunches by rotating transverse beamlets into the longitudinal plane using the emittance exchange (EEX) beamline of the Argonne Wakefield Accelerator (AWA).*-** This mechanism has been suggested, such as by the Compact X-ray Free-Electron Laser (CXFEL) group at Arizona State University, to hold the potential to make short-wavelength free-electron lasers (FELs) more compact. Our collaboration will pattern AWA’s 40 MeV electron beam with a TEM grid to produce micro-scale beamlets that will become mico-to-nano scale microbunches in the longitudinal plane. Characterizing an array of beamlets with a modulation period at the few micron scale and a low, single pC scale total charge presents challenges in achieving the necessary transverse resolution and signal strength. These proceedings will detail the diagnostics explored to characterize these transverse modulations. We will discuss the merits and challenges of each approach in relation to our application, and progress towards demonstrating these desired diagnostics.
Paper: MOP6355
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6355
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
MOP6375
Integration of X-Ray Diagnostics into Fast Orbit Feedback for Local Source Stabilization at NSLS-II
434
We present an accelerator-based X-ray beam stabilization approach that integrates X-ray beam position monitor (XBPM) signals into the fast orbit feedback (FOFB) system at NSLS-II. A high-speed electrometer and fiber-optic data link were developed to transmit XBPM position data to the storage-ring feedback controller at a 10 kHz rate. On the accelerator side, the XBPM signal is incorporated into the FOFB infrastructure as a virtual beam position monitor, allowing photon beam motion to be corrected through the electron beam orbit using fast corrector magnets. Experimental tests demonstrate suppression of dominant beamline vibration peaks near 27 Hz and 120 Hz when the feedback is enabled. These results demonstrate the feasibility of integrating photon diagnostics into accelerator feedback systems for improved X-ray beam stability and motivate the development of unified photon–electron feedback architectures for routine operation.
Paper: MOP6375
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6375
About: Received: 06 Apr 2026 — Revised: 14 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP6379
Implementation and design of a laser neutralizer in the LANSCE lebt
439
We present the detailed design and hardware implementation required to build a laser wire scanner for H- bunches at the Los Alamos Neutron Science Center (LANSCE) in the low energy beam transport (LEBT) section of the LANSCE beam line. The presented design is modular and supports a variety of input laser beam orientations, as well as differing laser beam diameters and powers. A custom-built laser interaction point, and drift chamber are added to the current beam line to photo-ionize the H- secondary electrons and collect the freed electrons in a custom-built, high-speed Faraday cup detector. Our chamber design is modular and constructed to minimally impact LANSCE production, while also allowing for in-run cycle reconfigurations. This setup will allow for the testing of a variety of laser system diagnostics configurations at the LANSCE facility. Future directions for direct separation and spatially resolved detection of the neutral hydrogen and charged anions will also be presented.
Paper: MOP6379
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6379
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
MOP6627
Development of Analog Electronics for the Beam Loss Monitoring System in the Superconducting Section of the CSNS II Linac
508
The analog electronics for the Beam Loss Monitoring (BLM) system in the superconducting section of CSNS II is mainly used for signal conditioning of the output signals from BLM beam loss detectors. For the BLM electronics of CSNS I, a single-channel transimpedance circuit was designed. The overall response time of the detector, transmission cable, and electronics is approximately 150 μs, with a focus on high-sensitivity design, which fails to meet the 10 μs response time requirement for machine protection in the superconducting section of CSNS II. Referring to the design of the LHC BLM electronics, a Charge-to-Frequency Conversion (CFC) circuit has been developed to split the charge generated by beam loss ionization into cumulative charge packets Qt with a fixed time interval T. Machine Protection System (MPS) triggers are generated by comparing the count from a counter with a calibrated unit-time count, and a high-speed ADC samples the frequency waveform to calculate the beam loss value through algorithms.
Paper: MOP6627
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6627
About: Received: 12 May 2026 — Revised: 19 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
MOP6644
THz-driven deflection of ultrashort electron bunch
539
Accurate characterization of longitudinal properties in ultrashort electron bunches constitutes a fundamental prerequisite for advancing scientific applications of compact particle accelerators. Here, we present an on-chip integrated terahertz (THz)-driven dielectric particle deflector based on the inverse Cherenkov effect: by coherently illuminating a high-breakdown-threshold right-angle prism with two linearly polarized lasers featuring a 180° phase difference, synchronized evanescent waves are excited on the prism’s hypotenuse surface, enabling phase matching between particle velocity and wave velocity to generate sustained transverse deflection forces. This method successfully reconciles the inherent constraints of optical laser bunch length and radiofrequency input power, while achieving scalable temporal resolution from 10 femtoseconds to the attosecond regime. Simulation results validate that the proposed scheme provides a robust technical platform for on-chip longitudinal bunch diagnostics and particle manipulation, holding significant application prospects in electron bunch-based scientific facilities.
Paper: MOP6644
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6644
About: Received: 15 Apr 2026 — Revised: 17 May 2026 — Issue date: 22 May 2026
MOP6650
Experimental verification of energy dependence in a CNT wire monitor for beam profile measurements in the J-PARC Linac
546
The J-PARC linac accelerates a 50 mA H⁻ beam up to 400 MeV for user operation. To mitigate emittance growth caused by space-charge effects, transverse beam profiles are measured using wire scanner monitors (WSMs) for routine beam tuning. Tungsten is generally used as the wire material. However, the WSMs employ carbon nanotube (CNT) wires in the low-energy region between the RFQ and DTL, because the beam energy is low as 3 MeV and the thermal load is substantial. CNT wires were introduced in 2017 as a more heat-resistant alternative, and since then they have operated without replacement due to beam-induced damage, demonstrating excellent durability. In this study, we report beam profile measurements obtained with the CNT WSM at various beam energies.
Paper: MOP6650
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6650
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
MOP6678
Development of an MTCA.4-Based High-Speed Data Acquisition System for Gas Monitor Detectors at S3FEL
590
This report presents the development and validation of a high-speed data acquisition system for Gas Monitor Detectors at the Shenzhen Superconducting Soft X-ray Free-Electron Laser (S3FEL). The system is designed to support real-time, pulse-by-pulse monitoring of photon intensity and beam position across six beamlines operating at up to 1 MHz repetition rate. Based on the MTCA.4 platform, the DAQ integrates custom front-end electronics with an AMC digitizer featuring four-channel 1 GSPS sampling and 14-bit resolution. Key innovations include dual-redundant fiber timing synchronization, PCIe-based real-time data streaming, and EPICS-integrated slow control. Preliminary tests confirm ADC linearity, low timing jitter, and sustained PCIe throughput, demonstrating the system’s readiness for deployment in MHz-class FEL facilities.
Paper: MOP6678
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6678
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
MOP6701
Application of Pyapas in PWFA
628
The Plasma Wakefield Acceleration (PWFA) experimental platform consists of two beamlines. Beamline 1 (BL1) transports the electron-positron beams from the BEPCII linear accelerator to the experimental station, with a beam energy of 2 GeV. Beamline 2 (BL2) is a linear accelerator featuring an energy of 150 MeV and a bunch charge exceeding 5 nC. Currently, both beamline accelerators have entered the beam commissioning phase. Pyapas, an independently developed High-Level Application (HLA) by the Institute of High Energy Physics (IHEP), has been successfully applied to beam commissioning of high-energy light sources. We have achieved the successful porting and application of Pyapas in the beam commissioning of the PWFA linear accelerators.
Paper: MOP6701
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6701
About: Received: 13 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
MOP7002
Experiment Design for Beam-based Characterization of a sub-THz Double Bend Mode Converter
638
Laser-based high power THz generation advances rapidly, enabling THz-driven electron acceleration beyond the breakdown limits of conventional RF-driven structures. For this purpose the polarization of the externally coupled THz pulse has to match the required TM₀₁ mode. Vice versa, beam-driven high power THz generation also relies on the TM₀₁ mode and requires efficient out-coupling and transport. A crucial step in both applications is the conversion between the fundamental mode and the TMTM₀₁ in a compact manner, which can be achieved efficiently in a double bend geometry¹. However, the double bend mode converter is fully integrated with the chained neighbouring devices. The embedding imposes challenges on the independent characterization of the converter, especially due to the strict tolerances. Utilising the wake field excited by an externally injected electron beam reduces the de-embedding complexity due to the requirements for THz in-coupling. Following tolerance studies, a beam-based experiment at ARES at DESY is proposed to study the conversion quality of the mode converter at 165 GHz, the design frequency envisioned for the TWAC project². The wake-driven excitation enables a wideband characterization around the design frequency. A gently compressed (≈1 ps rms) high charge (≈50 pC) electron bunch is passed through a dielectric loaded waveguide, thereby exciting the TM01 mode. The out-coupled, sub-µJ THz pulse will be polarization filtered to determine the relative mode content between the residual unconverted TM₀₁ and the expected TE₁₁.
Paper: MOP7002
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7002
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
MOP7010
Study and mitigation of transient beam loading in the double RF system of ALBA II
651
ALBA, a 3rd generation synchrotron light source in Barcelona, Spain, is currently preparing its upgrade to the 4th generation low emittance machine ALBA II. As part of this upgrade, an active normal conducting harmonic RF system will be installed to improve beam lifetime. However, discountinuities in the filling pattern, such as ion clearing gaps, induce RF cavity voltage variations along the revolution period. This effect, known as transient beam loading (TBL), severely degrades the bunch lengthening performance of the double RF system. In this contribution, we present a semianalytical study of the TBL effect in ALBA II as a function of gap size, together with a mitigation strategy. The results show that, by modulating the power delivered to the main and harmonic RF cavities at the revolution frequency, the impact of TBL can be effectively mitigated, limiting the degradation of the bunch lengthening performance to 2–18% for gap lengths ranging from 2–11%.
Paper: MOP7010
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7010
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
MOP7012
Power couplers conditioning and multipacting simulations for the ESS- Bilbao ARGITU RFQ
658
The ARGITU RFQ at ESS-Bilbao is a 352.2 MHz, 4-vane RFQ that will accelerate protons from 45 keV to 3.0 MeV. The RF power comes from a modulator/klystron by rectangular waveguides that end in coaxial lines that are finished by the two loop power couplers. The couplers are made of copper and no brazing has been used in their production. For this reason, the vacuum/air window is made of PEEK material attached by mechanical pressure to the copper structure. For the initial stages of the ARGITU RFQ, the duty cycle will not rise above 1%, so these couplers were designed with no active cooling. This paper summarizes the conditioning setup and focuses on the RF, thermal and multipacting simulations used to define safe high-power conditioning limits.
Paper: MOP7012
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7012
About: Received: 12 May 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
MOP7015
Multipacting in the 150 MHz flat-top cavity of HIPA: simulation, verification, and mitigation strategies
661
Local X-ray production, beam losses, and surface discolouration in colloidal graphite coated regions of the cavity indicate that multipacting continues to affect the operation of the 150 MHz flat-top cavity of the HIPA Ring Cyclotron. Particle-in-cell simulations were performed to confirm the phenomenon driving the issues and identify the specific operational conditions where it is driven. Simulations at the nominal cavity voltage show resonant electron trajectories between the electrodes and cavity wall, producing stable multipacting patterns consistent with observed surface discolouration. Guided by these results, the cavity geometry was modified to flatten the field minimum near the backplane, which demonstrated effective mitigation of multipacting undervarious operational conditions.
Paper: MOP7015
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7015
About: Received: 15 May 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP7017
RF properties of non evaporable getter coatings in the sub THz range
669
We report on the measurement of the surface impedance of thin sub-micron non-evaporable getter (NEG) coatings on a copper substrate, as used for distributed pumping in the vacuum system of the Swiss Light Source upgrade (SLS 2.0). Given the low electrical conductivity of NEG, a sub micron thickness with well known properties is required to avoid heat up and beam instabilities. Measurement frequencies around 100 GHz are required to obtain a good measurement sensitivity for these tiny coatings. A quasi-optical test stand based on a Fabry Perot principle uses one spherical mirror containing input and output couplers and a planar NEG coated probe mirror. 3D printing allowed to produce the spherical mirror together with the RF coupler and waveguide flanges in one integral part, which required only minimal additional processing. The setup is calibrated with the help of probe mirrors fabricated from bulk stainless steel and copper. For coated probes, we clearly saw the impedance changes caused by coatings with thicknesses in the 300 to 600 nanometer range and were able to prove their compatibility with the impedance requirements of the accelerator.
Paper: MOP7017
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7017
About: Received: 11 May 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP7018
X band Linac machine design for very high energy electron therapy
673
Very high energy electrons (VHEE) are a potential future modality in the field of radiotherapy. They have garnered considerable interest because they possess a unique combination of several properties including: being capable of deep tissue penetration (>30 cm), relative insensitivity to tissue inhomogeneities and being well suited to FLASH therapy. FLASH is the use of ultra-high dose rates which have been shown to reduce cell death in healthy tissue whilst maintaining toxicity to tumours. Recent studies indicate that higher energy beams produce less scattering and more precise dose delivery up to at least 250 MeV. This paper provides a design for a 250 MeV linac with dose rates exceeding 100 Gy/s in a 10 cm × 10 cm wide field size. The design is centred on a bi-periodic, π/2 mode, normal conducting, standing wave, accelerating cavity which emphasises stability. A gradient of 100 MV/m has been chosen to achieve the compactness potentially required to fit the accelerator in a hospital setting. To this end, 11.9942 GHz X-band technology has been selected which, along with extensive cell geometry optimisation, has produced a shunt impedance of > 95 MΩ/m and whilst minimising surface electric and magnetic fields.
Paper: MOP7018
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7018
About: Received: 12 May 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP7049
1.6 MW, 144 MHz solid state power amplifier for ELSA electron linac
739
The 19 MeV electron linear accelerator ELSA at CEA DAM has been in operation for 30 years. A renovation of the RF system was necessary to improve the reliability of the system. The second part of the renovation concerns the 144 MHz RF amplifier supplying power to the photo-injector. The former tetrode based amplifier has been replaced by a 1.6 MW Solid State Power Amplifier delivered by Ampegon company. One of the challenges was to design a compact amplifier to keep the same footprint. This paper will present the amplifier, the tests and the commissionning.
Paper: MOP7049
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7049
About: Received: 11 May 2026 — Revised: 15 May 2026 — Issue date: 22 May 2026
MOP7050
Conceptual design of a 0.2 MW pulsed 140 GHz gyroklystron amplifier and studies towards 1 MW operation for accelerator applications
742
Exploration of accelerator technologies in the millimeter-wave regime offers a promising route to achieve extremely high accelerating gradients. Owing to the high shunt impedance and short filling times of mm-wave accelerating structures relative to conventional S- and C-band systems, GV/m-level accelerating gradients become attainable. Mm-wave accelerator concepts are therefore of strong interest for applications including future linear colliders, charged-particle therapy, compact X-ray free-electron lasers (XFELs), and ultrafast electron diffraction (UED). We present the conceptual design of a pulsed 140 GHz gyroklystron amplifier intended as an RF power source for mm-wave accelerator systems. The interaction circuit adopts a two-cavity configuration composed of an input cavity, a drift section, and an output cavity. The electron beam is generated by a triode-type magnetron-injection gun (MIG) that provides operational flexibility, enabling adjustment of beam parameters and stable performance across a broad operating range. Design details of the MIG and the two-cavity interaction structure will be presented.
Paper: MOP7050
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7050
About: Received: 12 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
MOP7063
The New Calibration System for Magnetic Field Probes at the LNF-INFN Magnetic Measurement Laboratory
775
Accurate calibration of NMR probes is essential for high-quality magnetic-field measurements. Within the PNRR IRIS project, the Magnetic Measurement Facility (MMF) at LNF-INFN has implemented a new dedicated calibration system designed and manufactured by CAYLAR. The setup includes a 2.23 T dipole magnet with a 35 mm gap, a 1ppm four-quadrant power supply for low-field operation, and three NMR probes with associated electronics, covering the 200 G to 2.2 T range. The probes are mounted on a dedicated holder positioned in a highly uniform field region, ensuring that all sensors experience the same magnetic environment. Achieving excellent homogeneity over a large volume and wide field range was a key challenge; this was addressed through a genetic-algorithm-optimized magnet design complemented by active shimming coils. This contribution presents the system’s design, construction, and factory acceptance tests, along with the first calibration results obtained at MMF. Future improvements include thermostating the probe holder, potentially using cryogenic liquids, to extend the temperature range for calibrations, an important capability for probes used in superconducting magnets.
Paper: MOP7063
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7063
About: Received: 13 May 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP7086
Improving helium sustainability: current performance and upgrade of the ALBA helium liquefaction facility
824
Efficient use of gaseous and liquid helium, a non-renewable resource essential for accelerator-based experiments, is a key priority at ALBA Synchrotron Light Source. This work presents the operational status of ALBA’s helium liquefaction plant and the liquid-helium production achieved in recent years, based on recovery from its use in the BOREAS, LOREA, CLAESS and MSPD beamlines. The helium liquefaction plant’s operating mode is discussed, with emphasis on its main limitation: the system can only process recovered gas with an average helium purity of 99.5%. To overcome this constraint, the plant was upgraded during 2025–2026 with the installation of a gas purifier capable of treating gas helium with purities as low as 90%. The first operational results and performance of the helium liquefaction plant with the integrated purifier are presented.
Paper: MOP7086
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7086
About: Received: 11 May 2026 — Revised: 14 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP7089
SEY reduction using ultrathin TiN/NbN multilayers for accelerator applications
836
Multipacting and electron cloud formation remain major limitations for the performance of modern particle accelerators. In superconducting radio-frequency (SRF) cavities, multipacting can prevent stable cavity operation and restrict achievable accelerating gradients. In positively charged particle machines such as the LHC, the build-up of electron clouds results in beam instabilities, vacuum degradation, and additional heat loads on the cryogenic systems. Reducing the secondary electron yield (SEY) of vacuum-facing surfaces is therefore a key strategy to mitigate these effects. To mitigate these effects, several strategies have been proposed, in particular the deposition of thin films designed to reduce the secondary electron yield (SEY) of the relevant surfaces. We investigated the SEY behaviour of ultrathin TiN/NbN multilayers, with particular attention to the influence of both the number of layers and the TiN/NbN stacking sequence. Multilayers composed of individual 3 nm films were deposited by PVD to probe interfacial effects and possible electronic confinement phenomena. SEY measurements performed before and after electron conditioning reveal a dependence on the multilayer architecture. One particular multilayer configuration achieves a significantly reduced SEY, reaching 0.98 after conditioning.
Paper: MOP7089
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7089
About: Received: 07 May 2026 — Revised: 16 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP7099
Vacuum design and pressure modelling of the AWAKE Run 2c beamlines
854
AWAKE is the proton-driven plasma-wakefield acceleration experiment at CERN, currently preparing a major upgrade for Run-2c, scheduled to start in 2029. This phase will introduce new beamlines and extended infrastructure, including separate proton bunches-modulation and electron-acceleration stages, achieved in two plasma cells. These planned additions impose complex integration constraints across the facility. This contribution presents the updated vacuum layout - and its associated remote-control system - and addresses the integration challenges of multiple coexisting systems under vacuum, including the proton and diagnostic beamlines, two electron beamlines with their respective RF e-guns and RF waveguides, IR and UV laser transport lines. Each system features different pressure requirements and dedicated pumping strategies. Tailored pumping schemes were defined based on expected gas loads, operating scenarios and the limited space available. Analytical conductance and pressure calculations were performed to estimate baseline performance, while Molflow+ simulations were carried out for selected beamlines to characterize pressure profiles and validate the proposed pumping configuration. The contribution summarizes the vacuum-related challenges identified during the design and preparation for Run-2c and provides an overview for the upcoming installation phase.
Paper: MOP7099
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7099
About: Received: 08 May 2026 — Revised: 15 May 2026 — Accepted: 15 May 2026 — Issue date: 22 May 2026
MOP7102
Functionalised a-C coatings to reduce SEY and control surface resistance for the HL-LHC injection kicker beam-pipe ceramic supports
861
Functionalized amorphous carbon (a-C) coatings are being developed to reduce the secondary electron emission yield (SEY) and to control the surface resistance of ceramic supports for the new generation of HL-LHC injection kicker magnets. Pressure spikes observed during high-voltage pulsing of the new injection kicker magnets are attributed to flashovers caused by high electron emission and insufficient draining of surface charge on the alumina supports of the beam-pipe. To address this issue, the alumina supports for the next generation of injection kicker magnets are coated with an a-C film, providing suitable surface resistivity to prevent charge accumulation whilst preserving the insulating function of the supports, together with a low SEY. This contribution reports on the R&D programme aimed at tuning the resistivity of the a-C films through hydrogen doping while maintaining acceptable SEY performance. Results from the production of a series of 25 coated supports are presented, along with comple-mentary studies carried out to optimise the coating pro-cess for future large-scale production. The potential of these resistive a-C films as alternatives to Ti and TiN coatings for insulating components is also discussed.
Paper: MOP7102
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7102
About: Received: 13 May 2026 — Revised: 15 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP7103
Towards laser roughening of inner beam screen surfaces for electron cloud mitigation in standalone magnets around IP1 and IP5 of the LHC
865
Laser-induced surface roughening facilitates secondary electron yield reduction of materials [1]. The lab-based demonstration on small scale in 2014 motivated an initiative to scale-up the technology for processing of long vacuum components with inner surfaces to be treated in apertures < 50 mm, which is challenging. To address this, we have developed a technique that enables the selective transformation of the inner beam screen (BS) surfaces in LHC standalone magnets for electron cloud mitigation [2]. This requires scanning the light generated by a pulsed laser across the surface of ~10 m long BSs. The developed system consists of an IR laser and a 17 m long optical fiber that transmits the light to an inchworm mole, which houses an optical focusing unit and allows to scan the laser spot. We will present our solutions to the emerged challenges: *i)* mitigate surface oxidation, *ii)* avoid the contamination of cryosorbers, *iii)* integrate a synchronized fiber management system, *iv)* assure an acceptable treatment speed, *v)* find a compromise to match all material requirements, *vi)* extract ablated particulates, *vii)* monitor the process for quality control, and *viii)* perform a post-processing cleaning. By combining these steps, the influence on the beam impedance was minimized, and the compatibility with LHC operation was demonstrated. [1] R. Valizadeh et al, Appl. Phys. Lett. 105 (2014), 231605. [2] Elena Bez et al., RSC Appl. Interfaces 2 (2025), 521.
Paper: MOP7103
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7103
About: Received: 11 May 2026 — Revised: 14 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
MOP7124
Overview of superconducting undulator development at the European XFEL
916
This contribution describes the recent progress of the European XFEL superconducting undulators (SCUs) program. This includes: an industrially-produced NbTi-based SCU afterburner foreseen for one of the two hard X-ray lines; a prototype SCU module (S-PRESSO) in production by Bilfinger; two magnetic measurement test stands to perform quality assurance; and further development of SCU technology to reach even larger magnetic fields, by leveraging recent developments in High Temperature Superconducting (HTS) tapes for future upgrades.
Paper: MOP7124
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7124
About: Received: 11 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP7141
Development of a high-temperature electron beam test stand for thermal studies of the TATTOOS target at PSI
967
The Targeted Alpha Tumor Therapy and Other Oncological Solutions (TATTOOS) facility at the Paul Scherrer Institute (PSI) will address the growing demand for medically relevant radionuclides using proton-induced spallation at the PSI High Intensity Proton Accelerator (HIPA). The target is designed to operate with a 100 microA - 590 MeV proton beam at up to 2400 °C for 2–5 weeks. To study thermal mechanisms critical to target performance, a high-temperature test stand was developed based on PSI’s 60 keV, 100 mA electron beam welding machine. This setup allows heating tantalum foils in vacuum to melting temperatures while investigating thermal shock response, emissivity enhancement techniques, and temperature distributions using a Gaussian beam profile with wobbling frequency up to 1000 Hz. We will present here the static and wobbled beam profiles measurement using a 50 μm tungsten wire scanner moving up to 60 mm/s, with thermionic emission suppressed via voltage biasing. Then, FLUKA and CASINO simulations will show the penetration and scattering differences between the 590 MeV proton and 60 keV electron beams. Finally, temperature measurement for various rotation radii will be presented. Despite differing heating mechanisms, the resulting thermal behavior is directly comparable, supporting target design under realistic operating conditions.
Paper: MOP7141
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7141
About: Received: 15 Apr 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
MOP7153
RF window Ti coating characterization
1005
Thin titanium coatings were deposited on alumina RF windows at CERN to reduce the secondary electron emission yield. The deposition process was optimized to ensure uniform coverage of the components used in high-power RF systems. Witness samples were characterized to assess their suitability for accelerator applications. Surface resistivity was measured under controlled conditions, while the Secondary Electron Yield was evaluated to determine the effectiveness of the coating in reducing electron emission. Thickness uniformity was characterized through detailed mapping using Rutherford Backscattering Spectrometry at the Laboratori Nazionali di Legnaro, providing spatially resolved information on deposition homogeneity and confirming process reproducibility. These results provide a comprehensive overview of the properties of the titanium coatings and serve as a useful reference for optimizing surface treatments of RF windows in accelerator facilities.
Paper: MOP7153
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7153
About: Received: 13 May 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP7160
Electro-Magnetic Separator Topology Concept for FCC-ee
1025
The layout of the FCC-ee collider requires the separa- tion of the electron and positron beams, which are circu- lating in opposite directions, on either side of the RF sys- tem. Only one of the two beams must be deflected, while the other one (the beam circulating in the direction of the RF) shall remain untouched to avoid synchrotron radiation being emitted toward the RF section. This functionality is achieved using a combination of an electric field and a perpendicular magnetic field, which must be matched to each other along the entire length of the separator to avoid synchrotron radiation (SR) emission toward the supercon- ducting RF cryomodules. In order to satisfy the matching condition 𝐵 = 𝐸/𝑐 for relativistic particles, an extremely weak magnetic field (5 mT) is required for a given achiev- able static electric field (1.5 MV/m). This article presents a separator concept that combines an under-vacuum electro- static system with a low-field large-aperture outside-vacuum dipole magnet to achieve the main separation functionality while providing excellent field matching and low SR produc- tion. In addition to the concept development, three critical aspects have been identified and are the subject of ongoing studies to assess feasibility by end of 2027: high-voltage (HV) breakdown, beam coupling impedance and machine protection.
Paper: MOP7160
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7160
About: Received: 08 May 2026 — Revised: 17 May 2026 — Issue date: 22 May 2026
MOP7175
Large scale production of amorphous carbon coatings for the new beam screens of the HL-LHC project
1071
The new beam screens for the High Luminosity LHC (HL-LHC) will be coated with a low Secondary Electron Yield (SEY) amorphous carbon (a-C) thin film to suppress electron multipacting and reduce heat loads to the cryogenic system. The production will cover 40 beam screens for the new superconducting magnets of the inner triplets in LHC interaction regions 1 (ATLAS) and 5 (CMS), as well as 24 beam screens for the drift line of the cryomodules housing the CRAB cavities. This contribution presents the implementation of a large-scale coating facility dedicated to the deposition of a-C films on the various HL-LHC beam screens, adaptable to different geometries and lengths up to 14 meters. The rationale behind the chosen coating technology and process parameters is discussed, with emphasis on adhesion optimization, SEY minimization, and production throughput to meet the HL-LHC schedule. We report on the current status of the production campaign, including quality assurance statistics, and highlight the main challenges encountered together with the solutions adopted.
Paper: MOP7175
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7175
About: Received: 12 May 2026 — Revised: 15 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP7182
Metal Additive Manufacturing for Accelerator Technologies (MAAT project at INFN)
1096
The MAAT (Metal Additive Manufacturing for Accel-erator Technologies) project is a three-year INFN re-search programme launched in 2026, aimed at establish-ing Additive Manufacturing (AM) as a validated produc-tion route for high-performance accelerator components. MAAT brings together three INFN units: Legnaro (LNL), Padova (PD), and Milano LASA, combining complemen-tary expertise in superconducting RF, materials science, and advanced manufacturing. This paper reports on the activities and preliminary results during the first year of the project, covering: 1. the Design for Additive Manufacturing (DfAM) of 6 GHz cavities produced by Laser Powder Bed Fusion (LPBF). 2. the preliminary tests of the Wire Laser Additive Manufacturing (WLAM) combined with CNC ma-chining for the fabrication of a 1.3 GHz RF cavity prototype in CuCrZr.
Paper: MOP7182
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7182
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
MOP7191
Development of a Harmonised Framework for Electrical Safety Compliance at CERN
1115
Electrical safety has been identified as one of the main risks in large research infrastructures. At CERN, new regulations for electrical safety are being reviewed to align with current best practices and harmonise the approach. Among other aspects, it covers the compliance of electrical equipment and installations before they are put into operation, to further reduce the risk of accidents, to save time and cost by simplifying design processes, and to standardise the application of the legal requirements. While the new regulations were developed for CERN, they offer a model that can be applied to other research infrastructures. This paper describes the harmonised framework that was implemented to provide a practical guide for applying electrical compliance in the context of a research infrastructure. It was developed based on an analysis of best practices, validated through application to current CERN installations, and verified by industry experts. The framework optimises organisational efficiency by promoting ‘right-first-time’ compliance through a guided quality process. This work is part of the CERN Electrical Safety Project, an initiative established within CERN's Accelerator and Technologies sector to take proactive steps to further mitigate electrical risks, prevent recurrence, and build an even stronger safety culture.
Paper: MOP7191
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7191
About: Received: 12 May 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP7192
Design of an RF-gridded gun for a high-efficiency tristron
1119
The RF gridded gun is a key component of the RF power sources chosen for the FCC-ee tristron. It enables the generation of bunched electron beams via the application of an RF voltage across the cathode-grid gap. The tristron allows a compact tube architecture and provides high RF power production efficiency. The emitted, grid intercepted, and transmitted beam currents are governed by the applied RF grid voltage and DC cathode voltage, providing additional degrees of freedom for controlling the bunch formation. For continuous wave tristron operation at an RF power level of 0.5 MW in the UHF band, particular attention must be paid to several critical design aspects, including beam grid interception, beam optics design, thermomechanical effects, and stress. These factors strongly influence the operational stability, device lifetime, and overall performance. The current status of the RF gridded gun design for the tristron is reported
Paper: MOP7192
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7192
About: Received: 12 May 2026 — Revised: 17 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
MOP7303
RF design progress of the 197 MHz crab cavity for EIC
1131
The interaction region (IR) crab cavity system is a special RF system designed to compensate for the luminosity loss caused by the 25 mrad crossing angle at the interaction point (IP) of the Electron-Ion collider (EIC). The configuration includes six crab cavities in the Hadron (proton or ion) Storage Ring (HSR) - four operating at 197 MHz and two at 394 MHz - installed on each side of the IP, along with one 394 MHz crab cavity on each side of the IP in the Electron Storage Ring (ESR). This paper presents the recent progress in the RF design of the 197 MHz crab cavity, addressing the geometrical constraints, required crabbing voltages, multipole components, and the Higher Order Mode (HOM) power and impedance thresholds.
Paper: MOP7303
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7303
About: Received: 14 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
MOP8303
Standard and microbeam LINATRONs by Varex Imaging Corporation
1141
At Varex Imaging Corporation, High Energy Systems (HES) Department staff with help and support of our Production and Imaging groups continue adding new features to our LINATRON linear accelerator (LINAC) systems and transitioning new developments to our products. HES is at the final stages of productizing our usual LINATRONs, equipped with our new, in-house developed and built Accelerator Beam Centerlines (ABC). The products we offer today match or exceed the older products specifications, which were offered before we established our own ABC development and production line. In addition, we are making good progress on our new Microbeam LINATRON (MBL) systems, and we present the latest results on our MBL production prototypes. Our 6 MeV MBL6 prototype has been packaged, and it is under extensive testing and qualification process, getting ready for demonstration to our customers and for delivery. The similar packaging of our 3 MeV and 9 MeV LINATRON systems offers options of Ultra Low Leakage (ULL) shielding and of an integrated design packaging, now both for our security LINACs and for NDT LINACs under development.
Paper: MOP8303
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP8303
About: Received: 12 May 2026 — Revised: 17 May 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
MOP8304
Measuring and characterizing beam energy of a compact medical linear accelerator
1144
Tong Chen* (RefleXion Medical Inc.) Liang Huo, Tong Li, Hao Tao, Zhen Feng, Liang Hu, Lin Zhou, Yongtao Liu* (Chengdu Elekom Vacuum Electron Technology Co. Ltd) Beam energy is an important parameter of linear accelerator. Compact linacs for medical or industrial applications are usually not equipped with beam monitors. The commonly used methods are “half value layer” (HVL) in industrial and “Percentage Depth Dose” (PDD) in medical to evaluate the beam energy of linac. However, these methods are not easily and accurately carried out, the HVL method needs big and heavy steel plates to prevent scattering x ray beams and PDD method need standard beam position and expensive 3d water tank to measure the beam energy. Most importantly, those methods cannot measure electron beam energy, but the photon distribution generated through Bremsstrahlung. This article introduced a method to measure and characterize the average electron beam energy when hitting the target by combining the external measurements and simulation beam profile results under different deflection magnetic field generated by steering coils. This method not only gives confidence in developing and operating the medical equipment but also reveals relation between beam energy and RF power settings. In addition, this paper provides energy and dose output variation across the RF pulse. This data provides guidance for proper setting of gun pulse width and timing.
Paper: MOP8304
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP8304
About: Received: 30 Mar 2026 — Revised: 16 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP8604
Proof-of-principle experimental design of solenoid-based relativistic electron beam pulse compression
1150
Relativistic electron beam pulse compression can enhance the beam current intensity within the pulse and generate higher peak current, showing significant potential for applications such as FLASH radiotherapy and wakefield acceleration. This paper proposes a proof-of-principle experimental design for a solenoid-based electron beam pulse compression scheme. The core device of the experiment, namely the magnetic compressor, has an approximately cylindrical structure with a diameter of 42 cm and a height of 47 cm. By utilizing the uniform magnetic field generated by the solenoids, the compressor converts the energy difference of the injected beam bunch into a path-length difference to achieve pulse compression. Simulation studies show that, under a transverse geometric emittance of $10~\mathrm{mm\cdot mrad}$, the beam loss remains below 10%, while the output current waveform exhibits a peak-to-peak ratio of approximately 5, demonstrating an obvious pulse compression effect.
Paper: MOP8604
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP8604
About: Received: 13 May 2026 — Revised: 17 May 2026 — Issue date: 22 May 2026
MOP8617
Accelerator-driven radiation studies of YSZ-MgO composites for nuclear applications
1156
YSZ and YSZ-MgO thin films were deposited on Si (100) substrates using RF sputtering and RF-DC co-sputtering techniques and studied under low-energy heavy-ion irradiation. Two sets of films were prepared: YSZ sputtered in argon environment and YSZ and Mg co-sputtered in argon and oxygen environment. Irradiation studies show enhanced crystallinity in single-component YSZ and significant degradation of YSZ crystallinity in YSZ-MgO films. These results indicate a strong dependence of radiation response on composition of the material.
Paper: MOP8617
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP8617
About: Received: 18 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
MOP8619
A report from ISBA25, accelerator school in Shanghai, China
1158
ISBA25 (The 8th International School on Beam dynamics and Accelerator technology) was held from September 1 to 10 in Shanghai, China. This is the 8th school of the ISBA series, which is a international accelerator school for graduate students and young researchers who are new to the accelerator field. The school curriculum is composed of fundamental topics (e.g., RF theory), applications (e.g., medical accelerators), and the latest topics (e.g,. AI in accelerators). More than 90 students from around the world participated and spent meaningful days, including Hands-on training for accelerator design, student presentations, a laboratory tour of SARI, and an excursion. The school is reported.
Paper: MOP8619
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP8619
About: Received: 16 Apr 2026 — Revised: 18 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
MOP8621
High-power test of a 40kW industrial electronic linear accelerator
1164
Electron accelerators with high average power output are widely used in radiation processing fields such as material modification, food sterilization, and environmental pollutant treatment. This paper presents a comprehensive high-power test of a 40kW electron accelerator. Key parameters including electron beam energy, average beam current, output power, and pulse characteristics were measured. The results show that the accelerator’s electron beam energy, the average beam current, and the effective output power all meet the design specifications. The energy test was performed via the aluminum foil stacking method, ensuring high measurement accuracy. This study validates the reliability and stability of the accelerator, providing technical support for its industrial application.
Paper: MOP8621
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP8621
About: Received: 12 May 2026 — Revised: 16 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
MOV1003
FCC-ee injector complex: status, highlights and outlook
1171
The FCC-ee demands an injector complex capable of delivering high-current, high-brightness electron and positron beams with exceptional efficiency. Within the CHART/FCC-ee Injector Study collaboration, a revised injector layout has been developed to optimize performance, cost, and power consumption. A central pillar of this effort is the tuning-free, high-gradient normal-conducting RF structure technology pioneered at PSI for SwissFEL and since extended across S-, C-, and X-band systems. This scalable approach underpins future developments in the FCC-ee linacs, enabling reliable acceleration. In parallel, the P³ program at PSI is advancing the positron source, with commissioning foreseen in 2026, while upcoming work will enhance the electron source and refine RF requirements for the positron linac. This contribution presents the current injector complex status, key design highlights, and the outlook toward the FCC-ee injector technical design report.
Paper: MOV1003
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOV1003
About: Received: 14 May 2026 — Revised: 15 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP7368
ALS-U SR modules prestaging planning tool and methodology
1198
The Advanced Light Source Upgrade (ALS-U) project faces strict schedule requirements demanding rigorous planning of manufacturing assembly activities well in advance of assembly and installation. Delays of module components, and changes to the module tunnel installation sequence may significantly impact the module assembly (Prestaging) schedule for all 48 Storage Ring (SR) modules and therefore the installation of those modules during the 9-month SR removal and darktime installation period. To assess the adherence to schedule requirements, Prestaging developed a Visual Basic for Application coded planning tool to automate estimation of SR module assembly duration and resource needs. The tool methodology is based on bottom-up task sequencing where individual assembly tasks are laid out in succession with adjustments made for resource constraints and equipment conflicts. The model processes schedule and resource needs across 5 resource types for approximately 35 assembly tasks per module, generating duration estimates and resource profiles for SR module production. Functional testing has demonstrated the tool's capability to reduce planning time from approximately 4 hours of manual work per scenario-to-scenario processing to minutes while reducing inherent human error. With the model, Prestaging can quickly react to module component delays ensuring assembly planning is optimized within the constraints of the project. This contribution describes the model development methodology, functional testing results, and applications for future use during the ALS-U module assembly phase.
Paper: TUP7368
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7368
About: Received: 12 May 2026 — Revised: 18 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
TUO2M02
EuPRAXIA at ELI ERIC: development of a compact LPA FEL and plasma sources for ultrafast science
1208
The ELI Beamlines Centre, situated near Prague in the Czech Republic and operating as part of ELI ERIC, has been designated as the second pillar of the EuPRAXIA distributed user facility. It is developing a user-focused programme centred on laser–plasma accelerators (LPAs). A key initiative involves creating an LPA-driven free-electron laser (FEL) for the XUV and soft X-ray water-window ranges. The soft X-ray line will operate with approximately 1 GeV LPA electrons at 100 Hz, supporting research in biology, ultrafast chemistry, and nanoscale materials. The XUV line enables a broad scientific programme including time-resolved spectroscopy, attosecond dynamics, ultrafast magnetism, and surface science. The project utilises unique features of LPA-based FELs compared to LINAC-based facilities: naturally few-femtosecond electron bunches, high peak currents without needing compression, inherent sub-femtosecond synchronization with the drive laser, and a significantly smaller accelerator footprint. These features enable experimental regimes that are challenging for existing large-scale FELs, particularly in ultrafast pump–probe and attoscience applications. Complementary developments include betatron X-rays and a low-energy positron source from a kHz LPA accelerator, broadening user access to advanced plasma-driven radiation and particle beams within the EuPRAXIA framework.
Paper: TUO2M02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUO2M02
About: Received: 12 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
TUO8T02
Accelerators activities at ENEA for aerospace
1217
The ENEA Frascati Particle Accelerator Laboratory operates a set of S-band electron and proton linear accelerators providing beams relevant for radiation-effects studies in the aerospace sector. The TOP-IMPLART proton LINAC delivers low-energy (1–6 MeV) and high-energy (up to 71 MeV) beams, while the REX and TECHEA facilities supply 3.5–5 MeV and 1–3 MeV electron beams, respectively; both can also operate as X-ray sources via removable bremsstrahlung converters. The contribution reviews ENEA activities in aerospace applications, including irradiation of electronic components, material and shielding studies, and radiobiology and astrobiology experiments. ENEA is involved in several national and European projects— such as Cyptomars, Space It Up!, Space-EBC, and Thread — addressing key topics for space exploration. In parallel, ENEA provides irradiation services within infrastructures such as DIANA and ASIF supporting component testing and material qualification. This work highlights ENEA’s role in supporting the aerospace community through advanced accelerator capabilities, coordinated research initiatives, and a broad portfolio of irradiation services aimed at enhancing the robustness and space-readiness of technologies for future missions.
Paper: TUO8T02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUO8T02
About: Received: 11 May 2026 — Revised: 20 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
TUI3T01
High quality electron beams with tunable energy produced by laser-plasma acceleration
1228
Laser wakefield acceleration (LWFA) of electrons occurs when an intense short laser pulse focused in an underdense plasma drives in its wake a plasma wave with an amplitude large enough to trap and accelerate electrons. Relativistic electron bunches are easily obtained through this mechanism and have given rise to a large number of studies and publications. Despite these efforts, the achievement of a high quality reliable electron source, ready for use in applications, still needs some developments. Electron beams with high quality, and tunable electron energy, have been achieved by the authors using the DRACO facility (HZDR Dresden), showing that the injection and acceleration processes can be controlled consistently in a gas cell. Dark current free, relativistic electron bunches with energy peaked at tunable values between 60 MeV, and 200 MeV, 40 pC charge in the peak and sub-mrad rms divergence, reaching up to 14pC/MeV/mrad, have been achieved experimentally and reproduced in PIC simulations using measured input parameters. On going work is aimed at increasing the charge in the peak beyond 100pC through new gas cell development.
Paper: TUI3T01
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUI3T01
About: Received: 12 May 2026 — Revised: 19 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUI3T02
First direct observation of a wakefield generated with structured light
1233
Since their inception, laser-wakefield accelerators (LWFAs) have shown their capability to produce high-quality, monoenergetic electron beams. Yet, the push toward higher electron energies and more efficient accelerators is constrained by several limitations. Foremost among these are the dephasing and diffraction limits. A promising strategy to address these issues involves using structured light to modulate the on-axis propagation velocity in LWFAs. By pairing the diffraction-resistant properties of Bessel beams with spatio-temporal pulse shaping, this approach offers an unprecedented combination of extended acceleration lengths and strong acceleration gradients. Here we present the first experimental observation of wakefields driven by such structured beams. Spatio-temporally tailored pulses are directed through a specialized focusing mirror to form a quasi-Bessel beam, and the resulting wakefield is directly probed using femtosecond relativistic electron microscopy. Simulations corroborate the experimental data, offering novel insights into this underexplored regime. We show an experimental demonstration of the ability to modify the on-axis propagation velocity of the wakefield. We track the wakefield’s evolution throughout the focal region and examine how specific spatio-temporal manipulations influence both its structure and propagation velocity. Finally, we present the first results using such wakefields to accelerate electrons. These findings establish a foundation for harnessing structured-light-based strategies to overcome dephasing in LWFA. [1] A. Liberman et al., “Direct Observation of a Wakefield Generated with Structured Light,” Nature Communications, Accepted. (https://arxiv.org/abs/2503.01516) [2] A. Liberman et al., “First Electron Acceleration in a Tunable-Velocity Laser Wakefield,” under review. (https://arxiv.org/abs/2509.21098) [3] A. Liberman et al., “Probing Flying-Focus Wakefields,” under review. (https://arxiv.org/abs/2510.16950) [4] A. Liberman et al., "Use of spatiotemporal couplings and an axiparabola to control the velocity of peak intensity," Opt. Lett. 49, 814-817 (2024)
Paper: TUI3T02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUI3T02
About: Received: 10 Apr 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUO7T02
An ultra-high brightness cryogenic C-band RF gun for ultra-fast electron diffraction applications
1262
The electron source at the MOTHRA beamline is a novel 0.5-cell cryogenic C-band photoinjector designed to operate at gradients up to 200 MV/m. This work reports on recent developments toward implementing a load lock and modular cathode backplane that enables the insertion and testing of next-generation photocathode materials and structures under high-field, cryogenic operating conditions. The combination of a high launch field, low intrinsic emittance cathodes, and cryogenic temperatures is expected to significantly increase the achievable beam brightness. We present the current design status, experimental progress, and performance measurements of the cryogenic photoinjector with the modified backplane. In addition, we discuss beam-dynamics optimization for operating the source in an ultrafast electron diffraction (UED) configuration, where the high gradient and low intrinsic emittance offer a promising pathway to MeV-scale UED with exceptional brightness and temporal resolution.
Paper: TUO7T02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUO7T02
About: Received: 16 May 2026 — Revised: 21 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP2001
Statistical properties of attosecond SASE FELs
1271
Free electron lasers can now generate xray pulses with durations in the attosecond regime. Optimal utilization of the short pulses for attosecond science necessitates precise measurement of the pulse durations which there are promising methods to achieve. However, these are developing experimental techniques, not yet routine procedure. Until they mature, there is a wealth of information in the measured pulse energies and xray spectra, which are easily obtained. We show that while this information is insufficient to draw any conclusions about a single shot, with a large enough dataset, the statistics can determine length of the electron bunches, on average. FEL theory then predicts the distribution of the xray pulse durations. To achieve this, we extend the classical theory put in place by Saldin and Bonifacio to include short bunches with arbitrary current profiles, deriving integral expressions for some key statistical observables. The analytical is approach compared to 1D nonlinear simulations, showing good agreement until saturation sets in.
Paper: TUP2001
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2001
About: Received: 04 May 2026 — Revised: 16 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2002
Operational aspects of crab cavities at the Elettra 2.0 storage ring light source
1276
We investigate the upgrade of the Elettra 2.0 diffraction-limited storage ring light source with radiofrequency transverse deflecting cavities generating picosecond-long X-ray pulses of moderate intensity and high repetition rate. Based on a preliminary RF design, operational aspects, challenges and solutions to make the crab cavity scheme simultaneous to the standard operation of the facility, are presented and discussed, also in view of the users’ community wish list.
Paper: TUP2002
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2002
About: Received: 21 Apr 2026 — Revised: 19 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
TUP2316
Machine Learning based preventive maintenance and autonomous power control for RF cavities in a free-electron laser
1299
This project develops a machine learning–based system to prevent RF cavity trips in the free-electron laser by autonomously controlling the applied RF power. Sudden vacuum and current fluctuations within the cavities can cause reflections that trip the machine, and continuous manual monitoring throughout the conditioning process isn't feasible. To address this and potentially improve the conditioning efficiency, process-variable data was collected and analyzed to identify patterns in cavity behavior across operating power levels. A hybrid model combining clustering methods, linear regression, and a classifiers was designed to categorize current ranges, estimate baseline behavior, and detect anomalies. The resulting control program evaluates the machine state over short intervals, decreases power during unsafe conditions, increases it during prolonged stability, and can automatically reset the RF system after a trip. This approach enables faster and safer conditioning of the RF cavities, reduces operator workload, and provides a pathway toward fully autonomous preventive maintenance.
Paper: TUP2316
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2316
About: Received: 01 Apr 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP2330
RF conditioning and microwave gun simulations for the University of Hawai‘i Linac and FEL
1306
The S-band electron linac and free-electron-laser facility at the University of Hawai‘i at Manoa is being recommissioned after an extended period of inactivity. Following the restoration of vacuum and thermionic cathode systems, recent work focused on the high-power RF chain and on conditioning of the linac and microwave electron gun. We report RF conditioning measurements obtained during progressive power-up sessions at 1-4~Hz, including forward power delivered to the linac and forward and reflected power at the microwave gun. The linac RF response is stable and consistent with legacy calibrations, while the gun exhibits strong multipacting signatures. To guide the next conditioning campaign, we also present the developing RF-Track model of the thermionic TM010 gun, incorporating field maps, space charge, and beam loading.
Paper: TUP2330
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2330
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
TUP2331
First degraded beams in the CEBAF injector
1310
The electron beam degrader in the Continuous Electron Beam Accelerator Facility (CEBAF) injector at Jefferson Lab serves to generate electron beams with transverse emittance over 10x the nominal values, with the ultimate goal of using degraded electron beams to measure machine acceptance. Electron beams are degraded through multiple scattering in thin carbon foils, and maximum transverse emittance is defined through two collimating apertures. The degrader device was installed in late 2024, with commissioning and first beams on degrader targets during the 2025 physics run. We report on first operation of the degrader device.
Paper: TUP2331
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2331
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2333
Dual beam dynamic modes in a Compact Standing Wave Linear Accelerator
1317
Tong Chen* (RefleXIon Medical Inc.) Hao Tao, Liang Huo, Tong Li, Zhen Feng, Lin Zhou, Yongtao Liu* (Chengdu Elekom Vacuum Electron Technology Co. Ltd) It has been commonly observed that the beam spot profile of compact standing wave linacs have a dual Gaussian distribution. Further study of this paper shows that the two Gaussian distribution is generated by different acceleration process and beam dynamics. Simulation data analysis concludes that the particles in the two Gaussian distributions are strongly dependent on their initial phases. Experiment results have demonstrated the two Gaussian distributions responded differently to steering magnetic field.
Paper: TUP2333
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2333
About: Received: 30 Mar 2026 — Revised: 16 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
TUP2335
Ultraviolet transverse shaping with structured-stochastic phase-plates for photocathode applications
1320
Low-loss ultraviolet (UV) transverse shaping has emerged as a critical enabling technology for modern photoinjectors, with fused-silica phase-plates offering a robust alternative to conventional shaping methods. Building on our NAPAC2025 work, we introduce a new generation of enhanced UV phase-plates that use genetically seeded structured-stochastic designs and multi-level nanofabrication. These designs are initialized using spiral-zone-plate phase patterns and yield smoother transverse profiles at the photocathode while further reducing normalized emittance. At LCLS-I, these phase-plates achieve a 25% emittance reduction (0.6 um to 0.45 um); beating expectations of 20% reduction predicted by Impact-T simulations. For AWA, we fabricated 2-inch fused-silica masks compatible with the upgraded gun and beamline optics. Leveraging multi-level nanofabrication capabilities at the Center for Nanoscale Materials, we produced plates with reduced phase quantization error, enabling high-quality shaping. These results broaden the design space for low-emittance, jitter controlled photoinjector operation demonstrating the maturation of passive UV beam shaping into a facility-ready technology.
Paper: TUP2335
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2335
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2344
Electrical integration of the ALS-U storage ring modules
1345
The ALS-U (Advanced Light Source Upgrade) project is an upgrade to the ALS at the Lawrence Berkeley National Laboratory. The new multibend achromat (Storage Ring) will be installed in 16 months. To meet the tight schedule and space constraints, the 48 modules of magnets (called rafts) are prestaged and aligned in advance. All local electrical wiring is prestaged to reduce the installation time in the tunnel. Electrical work includes cabling for grounding, thermocouples, MPS (Machine Protection System), magnet power and correctors, vacuum, beamline feedback (diagnostics), and AC cables, all arranged to minimize heat buildup. Key challenges include raft transport requirements and managing the overall routing as well as future upgrades in the tightly packed lattice arrangement. This contribution presents the electrical integration on the raft during prestaging. It further outlines the testing activities and the prototype rafts developed to validate and optimize installation procedures. It details the schematics, cable and material management for the 48 rafts, as well as the ALS-U configuration management system and databases used for electrical routing.
Paper: TUP2344
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2344
About: Received: 22 Apr 2026 — Revised: 18 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
TUP2349
Finite element studies of the CANREB electron gun for a test stand setup
1351
The CANadian Rare isotope facility with Electron Beam ion source (CANREB) is an important component of the Advanced Rare IsotopE Laboratory (ARIEL) at TRIUMF. CANREB will deliver highly charged radioactive ion (HCI) beams for post-acceleration to nuclear physics experiments. Ion beams injected into CANREB are bunched using a ra- diofrequency quadrupole (RQB) cooler-buncher and energy adjusted using a pulsed drift tube for injection into an elec- tron beam ion source (EBIS) charge state breeder. Charge breeding occurs by collisions with an electron beam (up to 15 keV, 500 mA) produced by an electron gun. During EBIS commissioning, the electron gun became unstable at currents above 40 mA, with a large fraction of the beam intercepted by the anode. To address this issue, an electron gun with an updated design is planned to be fabricated and installed in CANREB. In order to characterise the new elec- tron gun, a test-stand will be built allowing for systematic testing. This paper describes a full simulation model of the test-stand using FEA software TRAK.
Paper: TUP2349
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2349
About: Received: 12 May 2026 — Revised: 17 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2350
Experimental reconstruction of source 4D phase space without prior knowledge of transfer matrix
1355
We use the PHOEBE test beamline at Cornell to experimentally demonstrate a simple method for reconstructing the transverse 4D phase space of an electron beam at the source from downstream aperture scans of the beam. This method does not rely on detailed knowledge of the beamline transport, besides assuming that linearity and symplecticity are satisfied. We apply this method to measure the source 4D phase space of electrons emitted from a spatially-structured alkali-antimonide cathode, and verify the fidelity of the reconstructed source spatial and momentum distributions.
Paper: TUP2350
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2350
About: Received: 18 May 2026 — Revised: 21 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2355
Experience Adjusting Beam Transport and Booster Synchrotron Systems for Different Linac Output Energies at the Canadian Light Source
1363
Due to linac operational issues, the Canadian Light Source has recently reduced the injection energy of its booster synchrotron from 250 MeV to 152 MeV. We found that we needed to be increasingly careful with the booster ring transverse tunes as we decreased the injection energy. We needed to make fine adjustments of the tunes during the low energy part of the ramp, requiring new software. Adjusting the energy compression system (ECS) and transfer line was mostly a linear process. Recent improvements in diagnostics and software have greatly simplified ECS and transfer line setup.
Paper: TUP2355
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2355
About: Received: 07 May 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP2606
Feasibility of a Compact X-ray Free-Electron Laser Oscillator based on Diffraction Limited Storage Ring
1371
X-ray Free-Electron Laser Oscillators (XFELOs) utilize Bragg crystal-based x-ray cavities to generate high-brightness x-ray pulses with ultra-fine bandwidth. The successful realization of XFELOs would greatly benefit high-resolution photon-hungry experiments, such as nuclear resonant scattering and inelastic x-ray scattering. Existing XFELO proposals, constrained by either the electron beam repetition rate or limited single-pass gain in the undulator, typically require long undulators and long cavities. In this work, we investigate the feasibility of a compact XFELO design, utilizing the 6-meter straight sections of a Diffraction Limited Storage Ring (DLSR) and a cavity path length well below 100 meters. We show that sufficient single-pass gain can be achieved by optimizing the undulator and electron beam parameters. We present the projected performance of the proposed scheme based on the parameters of the High Energy Photon Source (HEPS) and discuss the practical challenges associated with its implementation.
Paper: TUP2606
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2606
About: Received: 13 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
TUP2617
Study of gas scattering–induced beam losses and collimation for the SOLEIL II storage ring
1392
The SOLEIL II storage ring will be equipped with many in-vacuum undulators (IVUs) and superbends, which are vulnerable to gas scattering–induced beam losses due to their small vertical gaps. In this paper, gas scattering–induced beam losses in SOLEIL II are studied with tracking simulations. The results show that, without vertical scrapers, 53$\%$ of elastic scattering–induced losses happen at IVUs with 4 mm vertical gaps, posing a risk of damage to their magnets over 15 years of operation. Detailed tracking finds that most of these losses originate from scattering events in short range, e.g., within half a turn. This suggests that one vertical scraper located upstream of each IVU group could provide optimal collimation, protecting the IVUs while maintaining the beam lifetime. However, this scheme is not allowed due to space constraints. A second optimal vertical collimation scheme is proposed with 2 scrapers, which reduces the beam losses at IVUs by 40$\%$ while maintaining an elastic scattering lifetime of 40 hours. In contrast to elastic scattering, inelastic scattering leads to only minor beam losses and remains acceptable.
Paper: TUP2617
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2617
About: Received: 12 May 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP2630
Updated orbit stability evaluation for the Korea-4gsr Incoporating new mechanical and beam disturbance measurements
1415
Beam orbit stability is a critical requirement for fourth-generation synchrotron radiation facilities. An initial evaluation for the Korea-4GSR quantified expected orbit disturbances from ground vibration, magnet current ripple, and energy oscillations. Since that baseline study, additional measurements and refined models have enabled a more accurate assessment. Newly acquired ground-motion data provide updated vibration spectra affecting magnet and girder motion. Orbit fluctuations induced by the EPU and the canted-ID configuration have been characterized and incorporated into the analysis. Vacuum-chamber vibration, previously unaccounted for, has also been measured to assess mechanical coupling to the beam. Using these updated disturbance sources, revised orbit-stability predictions have been obtained through beam-dynamics simulations. The study identifies the dominant contributors under current design conditions and discusses implications for orbit-feedback performance and mechanical design optimization.
Paper: TUP2630
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2630
About: Received: 18 May 2026 — Revised: 21 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2632
Recent progress on the infrared free-electron laser facility of Anhui University
1419
Since May 2022, the researchers at Anhui University, Hefei, China have been constructing an internationally advanced infrared free-electron laser (IR-FEL) facility. The project mainly includes one FEL light source device, six experimental stations, and other supporting systems. The tunable IR-FEL system covers the mid-infrared to far-infrared bands. Its linear accelerators provide an electron beam energy of 12-55 MeV, adopting an oscillator-type FEL scheme to generate ultrashort laser pulses (maximum 100 mJ/pulse) with continuously tunable wavelengths (2.5-200 μm), quasi-monochromaticity, and high peak power. The system includes linear accelerators, oscillators, and an optical transmission system, along with electron beam diagnostics, synchronization control, and laser parameter measurement systems. The six experimental stations focus on high temporal, spatial, and energy resolution to realize the characterization and measurement of light-matter interactions, constructing an internationally advanced materials science research platform for light-matter interaction studies.
Paper: TUP2632
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2632
About: Received: 02 Apr 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP2635
Multi-objective bayesian optimization of multi-stage OK-SASE for efficient high-energy XFEL operation
1422
Femtosecond hard X-ray radiation beyond 12.4 keV enables unprecedented opportunities for probing matter at atomic scales, however, its generation remains challenging for self-amplified spontaneous emission (SASE)-based XFELs due to reduced FEL gain, leading to extended undulator requirements and limited radiation efficiency. To address this issue, we investigate a multi-stage optical-klystron SASE (OK-SASE) scheme that enhances microbunching through dispersive sections and shortens the gain length. A multi-objective Bayesian optimization (MOBO) framework is introduced to systematically optimize the configuration. Using SHINE as a representative case, steady-state simulations at 15 keV show that the optimized setup reduces the required undulator length relative to conventional SASE by about 7% to 22%, depending on the electron-beam energy spread. The optimization indicates that several chicanes can remain effectively inactive, enabling a more compact beamline layout. Time-dependent simulations also demonstrate the feasibility of multi-stage OK-SASE for efficient high-energy XFEL operation.
Paper: TUP2635
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2635
About: Received: 30 Mar 2026 — Revised: 21 Apr 2026 — Accepted: 15 May 2026 — Issue date: 22 May 2026
TUP2636
Modeling of CSR and its cancellation in DBA/Chicane type compressors
1426
In advanced accelerator-based light sources and colliders, bunch compressors like arc-type (DBA) and linear-type (chicane) are widely used to generate high-quality electron beams with kiloampere (kA)-level peak currents. However, a serious problem in increasing the peak current even higher is the significant degradation of beam quality caused by the Coherent Synchrotron Radiation (CSR) effect. To tackle this, we develop a new analytical model for CSR that can describe beam transport with varying bunch lengths, establish a practical framework for analyzing CSR in both DBA and chicane-type compressors, and design CSR-suppressed DBA compressors (arc-type) as well as non-symmetric C- and S-shaped chicanes (linear-type). General analytical conditions for CSR cancellation are derived for these designs. Simulations show that, with these new compressors, high beam quality can be maintained even when the peak current is increased up to 10 kA. This work provides important guidance for enhancing the performance of existing accelerator facilities, as well as for the development of next-generation accelerator-based light sources and colliders.
Paper: TUP2636
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2636
About: Received: 13 May 2026 — Revised: 16 May 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
TUP2639
Theoretical Analysis of a Novel Seeded Free-Electron Laser Scheme with the Same Layout as EEHG
1433
Seeded free-electron lasers (FELs) are advanced, accelerator-based light sources characterized by high coherence and stability. In our previous research, we proposed an intelligent optimization framework for studying the micro-bunching process in seeded FELs. Using this framework for exploratory optimization, we identified a novel seeded FEL scheme. This scheme employs an optical layout identical to echo-enabled harmonic generation (EEHG), but by adjusting the parameters of the seed lasers and chicanes, it achieves bunching factors exceeding the theoretical limit of conventional EEHG. In this paper, using a representative set of realistic beam parameters, we demonstrate how this novel scheme induces a high harmonic density modulation in the electron beam. Then, we theoretically analyze this novel seeded FEL, presenting its underlying principles.
Paper: TUP2639
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2639
About: Received: 11 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP2640
Recent progress in intense vortex radiation sources at SXFEL
1436
Vortex radiation carries orbital angular momentum (OAM) and is attractive for applications including chiral characterization, magnetic imaging, and ultrafast light--matter interaction studies. A scheme for vortex radiation generation and diagnostics at the Shanghai Soft X-ray Free-Electron Laser facility (SXFEL) based on wavefront shaping of a 266 nm external seed laser is studied. Three-dimensional simulations with realistic SXFEL parameters show clear annular intensity and helical phase distributions, with peak power reaching the sub-gigawatt level at a representative working point. The proposed diagnostics further enable clear identification and characterization of the generated OAM radiation. The results support the feasibility of controlled vortex radiation generation at SXFEL and its future extension to shorter wavelengths.
Paper: TUP2640
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2640
About: Received: 31 Mar 2026 — Revised: 17 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP2641
SymCSR: Tracking 6D phase space dynamics of electron beam with coherent synchrotron radiation
1440
Coherent synchrotron radiation (CSR) is a critical effect in the design and operation of high-brightness electron accelerators, as it can lead to significant energy loss and emittance growth. In this paper, we present SymCSR, a first-principle tracking program for simulating the 6D phase space dynamics of electron beams under the influence of CSR. SymCSR computes the radiation reaction field of electrons based on its retarded and instantaneous trajectory, which efficiently reduces the requirement on macroparticle numbers. The dynamics of electron beam in various dimensions are calculated using SymCSR and are compared with theoretical models.
Paper: TUP2641
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2641
About: Received: 13 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP2646
Analysis of slice energy spread increased by intra-beam scattering at the SHINE Injector and Linac
1444
Intra-beam scattering (IBS) can substantially enhance the slice energy spread of high-brightness electron beams, thereby degrading the performance of free-electron laser (FEL) facilities. This effect is particularly detrimental for advanced operation modes such as self-seeding, which impose stringent requirements on beam longitudinal coherence. Consequently, an accurate evaluation of IBS growth in both the injector and the main linac is essential. SHINE, the first superconducting-linac–based FEL facility in China, has recently completed beam commissioning up to the first bunch compressor (BC1). In this work, we present a theoretical and numerical analysis of IBS-induced slice energy spread growth throughout the SHINE injector and linac. The analytical estimates show good agreement with start-to-end simulations, confirming that IBS leads to a significant increase in slice energy spread already at the injector stage. These results highlight the necessity of incorporating IBS considerations into the beam dynamics design and optimization of high-repetition-rate FEL facilities such as SHINE.
Paper: TUP2646
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2646
About: Received: 18 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
TUP2657
Off-axis hollow-channel plasma tailoring for generating two-color x-ray free-electron lasers
1448
Plasma-wakefield-based acceleration offers a route to realize compact X-ray free-electron lasers, but its application is currently limited by beam quality. Two-color X-ray FEL pulses provide a powerful tool for probing ultrafast dynamics. Here we propose a scheme for generating such pulses by using an off-axis elliptical hollow-channel plasma to tailor the electron-beam phase space while preserving its quality. In this approach, the plasma wakefield imprints a time-dependent transverse tilt along the bunch, while the elliptical channel geometry effectively suppresses the quadrupole wakefield and minimizes the induced mismatch. This enables fresh-slice lasing control at different wavelengths in two undulator sections. Simulations show the feasibility of generating femtosecond-scale, high-power two-color pulses with tunable temporal separation at the Shanghai Soft X-ray Free Electron Laser facility.
Paper: TUP2657
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2657
About: Received: 16 Apr 2026 — Revised: 14 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2661
Design study of injector system using rf electron gun with gridded thermionic cathode towards soft X-ray free-electron laser
1452
The high-brightness synchrotron radiation facility “NanoTerasu” provides users with extremely stable synchrotron radiation by top-up injecting an electron beam from a 3-GeV linear accelerator into a diffraction-limited storage ring. NanoTerasu plans to develop a soft X-ray free-electron laser (SX-FEL) using the linear accelerator. To realize SX-FEL with practical gain length, it is required that the linear accelerator generates an electron beam with a peak current of 2 kA and a normalized emittance of 2 mm mrad or less. We have already developed a low-emittance electron gun system with a gridded thermionic cathode and have begun designing a low-emittance injector system using the electron gun system. The linear accelerator based on the electron gun system is planned to serve as both the storage ring’s injector and SX-FEL’s driver. This presentation describes the configuration of a compact SX-FEL linear accelerator that can be installed within existing facilities. It also presents a bunch compression scheme while maintaining slice emittance, along with particle tracking simulation results of the new injector system.
Paper: TUP2661
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2661
About: Received: 11 May 2026 — Revised: 20 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP2664
Optimization of a storage ring pre-injector for high transmission efficiency and low energy spread
1456
In this paper, the Non-dominated Sorting Genetic Algorithm II (NSGA-II), combined with the beam dynamics code ASTRA, was employed for the multi-objective optimization of the output performance of an electron linear accelerator (linac). Taking the pre-injector of a storage ring light source as an example, the electron linac consists of a thermionic cathode high-voltage electron gun, a sub-harmonic buncher (SHB), a buncher, and a traveling-wave accelerator tube. Maximizing the transmission efficiency and minimizing the energy spread were defined as the core objectives of the optimization. The optimization results indicate that the beam energy at the linac exit reaches approximately 65 MeV, with the transmission efficiency exceeding 70% and the energy spread maintained below 0.35%.
Paper: TUP2664
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2664
About: Received: 15 Apr 2026 — Revised: 18 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP2665
Beam dynamics analysis of an electron microtron using General Particle Tracer
1460
Electron microtrons are extensively employed as injectors for tabletop light source facilities. In this paper, a 5 MeV electron micrtron is designed, and an external injection scheme is adopted to achieve a large stable longitudinal phase region. We investigated the beam dynamics of this microtron using General Particle Tracer (GPT). After optimization, the width of stable longitudinal phase region is approximately 40°, which is about four times larger than that of conventional internal-injection microtrons.
Paper: TUP2665
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2665
About: Received: 25 Mar 2026 — Revised: 15 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
TUP2668
Preparation and research of CsBr-Coated Cs3Sb photocathodes
1466
Abstract Cs$_3$Sb photocathodes are promising electron sources for accelerators because of their high quantum efficiency (QE) under visible light, but the low robustness under low vacuum limits practical operation. In this work, Cs$_3$Sb photocathodes coated with CsBr were prepared and characterized. The experimental results indicate that the coating improved the pressure adaptability of the photocathodes by approximately two orders of magnitude, although it inevitably reduced the initial QE. After exposure, the QE of the coated photocathode can be recovered by annealing to its original value.
Paper: TUP2668
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2668
About: Received: 01 Apr 2026 — Revised: 29 Apr 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
TUP2670
The collimator system for reducing the dark current in NSRRC photoinjector
1469
The NSRRC photoinjector generates ultrashort electron beams for the production of superradiant radiation in the 100–500 μm wavelength range using a gap tunable U100 planar undulator. The accelerator consists of an S band, laser driven photocathode RF gun equipped with a compensation solenoid, followed by a 5 m long linear accelerator. Sub picosecond electron bunches are achieved through velocity bunching in the linac. Under specific operating conditions, electrons emitted from the cathode surface may be accelerated to high energies independently of the main beam, which continues to gain energy in the linac. These stray electrons can impact the vacuum chamber, producing unwanted radiation that poses risks to both accelerator components and radiation safety. To suppress dark current, a collimator was installed between the photocathode gun and the linac to intercept these electrons prior to downstream transport. Experimental measurements and numerical simulations are presented, demonstrating the effectiveness of the collimator system in reducing dark current.
Paper: TUP2670
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2670
About: Received: 11 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2672
Design of a 10-MHz high-energy-resolution light source
1472
High energy resolution is essential for advanced spectroscopic studies of quantum materials, especially for resolving low-energy electronic features in angle-resolved photoemission spectroscopy (ARPES). However, existing light sources for ARPES still face difficulties in simultaneously providing narrow bandwidth and high photon flux. We are developing a 10-MHz coherent light source based on angular-dispersion-induced microbunching (ADM), aiming to generate narrow-band radiation with sub-meV-level energy resolution. Start-to-end simulations from the injector to the radiator have been performed to evaluate the beam dynamics and radiation performance. The simulation results show that the proposed source can provide sub-meV-level energy resolution and a photon flux above $10^{12}$ photons/s over a broad photon-energy range.
Paper: TUP2672
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2672
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP2679
Symplectic Tracking of Damping Wigglers Using Generalized Gradient Representations
1488
Strong wigglers are installed in the storage ring to provide a strong damping effect and thus can make the particle beam reach an equilibrium state quickly. Nevertheless, particle tracking of damping wigglers with strong peak field strengths typically uses the field map analysis approach, which does not account for radiation effects and quantum excitations in ELEGANT. To address this, the Generalized Gradient Expansion (GGExp) method is employed to describe the strong magnetic fields of damping wigglers in storage rings. The GGExp method provides an alternative approach to define the wiggler field, incorporating synchrotron radiation effects with symplectic tracking, and offers benefits for both linear and nonlinear analysis.
Paper: TUP2679
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2679
About: Received: 09 May 2026 — Revised: 21 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2686
Investigation and diagnostic potential of off-axis resonance in THz Free-Electron Lasers
1504
We study undulator radiation observed away from the beam axis for terahertz (THz) free-electron laser (FEL) beams. Earlier work on a single short bunch relates the continuous off-axis spectrum to the longitudinal bunch profile , without a discrete angular ‘resonance’ tied to micro-bunch harmonics. For a pre-bunched pulse-train beam, the bunching factor develops narrow spectral lines at the fundamental frequency and its integer harmonics. Off-axis phase matching selects a specific resonant polar angle for each line, producing pronounced, spatially separated ring-like intensity patterns in the coherent far field. We utilize the non-averaged 3D FEL code PUFFIN to simulate single-bunch radiation—reproducing non-integer harmonic patterns consistent with analytical Lié-nard-Wiechert (LW) results—and to demonstrate the expected off-axis resonance for pulse-train beams.
Paper: TUP2686
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2686
About: Received: 17 May 2026 — Revised: 18 May 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
TUP2691
Using Stretching-Modulation-Compression effect to generate isolated few-femtosecond MeV electron bunches
1512
Femtosecond electron beams serve as effective tools for investigating ultrafast dynamic processes in matter, providing complementary capabilities to femtosecond laser beams. We propose and demonstrate the feasibility of a scheme combining an undulator with THz modulation to generate isolated few-femtosecond electron bunches. We have developed a theoretical method that incorporates the transport dynamics of low-energy relativistic electrons interacting with the THz modulation field in the undulator and the space charge effects within the bunch itself. The results indicate that the proposed scheme can generate single isolated ultrafast electron bunches with kinetic energy 3 MeV, bunch length about 6 fs (rms) with core charge up to 0.1 pC. We have also evaluated the potential influence of several relevant physical quantities on the final bunch length and arrival time, and provided some scaling relations with respect to the initial bunch charges. The proposed scheme and the developed theoretical model presented may provide useful insights for generating few-femtosecond electron bunches or even shorter attosecond electron bunches in accelerator-based ultrafast electron facilities.
Paper: TUP2691
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2691
About: Received: 07 May 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP2695
Commissioning of the injector system for the X-band electron linear accelerator in Melbourne
1516
The University of Melbourne’s X-band Laboratory for Accelerators and Beams (X-LAB) is developing a compact electron linear accelerator. The injector system will consist of a 100 keV DC photogun, a pulsed UV laser, an S-band (2.9985 GHz) RF buncher, and magnetic elements for beam transport. This paper reports on the commissioning of the injector system. We present the characterisation of the test laser and buncher, as well as initial electron beam measurements with Faraday cup. Particle tracking simulations using General Particle Tracer (GPT) code were used to obtain approximate optimal solenoid currents. We also report on the conditioning of the photogun, including photocathode inspection, vacuum performance, dark current, and stray radiation.
Paper: TUP2695
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2695
About: Received: 12 May 2026 — Revised: 21 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP2697
Analysis of beam loading effect of dark current in C-band photocathode electron gun
1520
In the research on high-gradient photocathode electron guns, the existence of dark current not only affects the measurement of photo-beam but also causes problems such as secondary electron multiplication and an increased difficult of condition. In this paper, the sources of dark current emission inside the electron gun and their impact duiring the power test are discussed through simulations. Additionally, combined with the test results from the C-band electron gun test platform in the pre-research project of the Southern Advanced Photon Source, the beam loading effect introduced by dark current is analyzed. The results show that when the dark current in the test is > 10 mA, it will increase the coupling parameters of the cavity and reduce the cathode accelerating field gradient.
Paper: TUP2697
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2697
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
TUP2707
Study on polarization control of planar undulator system based on magnetic field modulation
1535
The fast polarization switching of undulator radiation has attracted more and more attention in recent years. Recently, a new method has been proposed for fast polarization switching up to kilohertz of undulator radiation by using magnetic field modulation generated from low-current electromagnetic coils. Through fast switching the power of coils, the radiation spectra of two undulators can be rapidly shifted into and out of the bandpass of a monochromator, enabling fast polarization switching for the user beamline. In this paper, we have studied the performance of the scheme using planar undulators. The performance of related parameters, such as photon flux, polarization degree, and spot distribution, will be reported.
Paper: TUP2707
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2707
About: Received: 18 May 2026 — Revised: 21 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP2708
The essence factor to deteriorate the circular polarization radiation performance in APPLE-KNOT undulator
1539
The APPLE-KNOT undulator forms composite magnetic fields by superimposing APPLE and KNOT fields with different period lengths. In this configuration, in which the APPLE field serves as the dominant component to approximate the target photon energy, while the KNOT field acts as an additional component to transversely deflect the electron beam off-axis. Although variable polarization modes can be realized with a low on-axis heat load, previous studies have observed a sharp reduction in flux and significant degradation of the polarization degree in the circular polarization (CP) mode. This paper discusses this phenomenon in detail from a theoretical perspective. The analysis reveals that the presence of an additional field with a longer period is the essence factor that inherently suppresses the radiation performance of CP mode. Theoretical findings are highly consistent with simulation results, demonstrating that selecting the KNOT field as the dominant component can effectively improve CP characteristics without significantly compromising the linear polarization performance.
Paper: TUP2708
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP2708
About: Received: 15 Apr 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP3008
Research status on the ECRIPAC accelerator concept
1558
This study presents the current advancement on our investigation of the Electron Cyclotron Resonance Ion Plasma Accelerator (ECRIPAC), revisiting and greatly expanding this original accelerator concept initially developed in the nineties\*. ECRIPAC is an innovative compact plasma device able to generate energetic pulsed ion beams using robust and well mastered electron cyclotron resonance ion source technologies, without requirements for axial RF cavities or powerful laser beams. It relies on the gyromagnetic auto-resonance of plasma electrons in a time growing magnetic field\*\*, followed by the axial acceleration of ions through the plasma space-charge field inside a magnetic field gradient, up to energies close to 100 MeV/A. The theoretical behaviour of ECRIPAC is summarized. Some preliminary results of kinetic plasma simulations inside a preliminary design of an ECRIPAC machine able to accelerate He2+ ions up to approximately 10 MeV/A are presented. Two sets of simulations are considered, one working with a cylindrical geometry and azimuthal mode decomposition in the open-source code Smilei\*\*\* and the other using a 3D geometry in the open-source code WarpX\*\*\*\*, providing interesting insights on the plasma behaviour inside the accelerator.
Paper: TUP3008
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3008
About: Received: 12 May 2026 — Revised: 20 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP3010
SMART - a SMall pArticle accelerRaTor on chip
1565
The miniaturization of particle accelerators via Dielec tric Laser Acceleration (DLA) * offers a route to ultra compact, cost-effective devices poweredbycommerciallaser systems. This work explores the extension of DLA technol ogy—historically focused on electrons—to protons, aiming to enable "on-chip" sources of high energy hadrons. We present the design and simulation of a novel microstruc ture optimized for the acceleration of non-relativistic pro tons. Key challenges addressed include the management of phase slippage and the requirement for strong transverse confinement of heavy particles at low 𝛽. This study aims to demonstrate the potential for stable acceleration and fo cusing, validating the pDLA(proton-DLA) ** concept as a viable candidate for future compact accelerator architectures.
Paper: TUP3010
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3010
About: Received: 24 Apr 2026 — Revised: 17 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
TUP3014
Interaction of high-intensity beam with structured solid surface plasma for wakefield acceleration and coherent radiation generation
1568
Recent research into the interaction between high-intensity beams and surface plasmas has revealed the significant potential of generating extremely strong (~TV/m) fields for particle acceleration and radiation production. This new approach has emerged by overcoming several challenges in beam-solid interactions. It therefore holds great promise for reshaping the research direction of large-scale facilities pursuing the energy frontier and micro-scale facilities requiring great flexibility. At the same time, this research can provide new insights into the extremely complex nonlinear dynamics of surface plasmons (SPs) in strong fields and a new, unexplored regime of plasma-based particle acceleration. In this study, we theoretically investigate the high-intensity laser- or beam-driven excitation of relativistic surface plasmons on the micro-scaled surfaces of structured nanomaterials, such as vertically aligned carbon nanotube (VACNT) forests. Leaky and bubble wakefields can be generated with amplitudes exceeding 400 TV/m and high energy efficiency for both electron and positron acceleration. By investigating SP mode selection on cylindrical surfaces, we have proposed a new principle for coherent radiation generation that differs fundamentally from traditional superradiance. Our research offers a new approach to the development of ultrahigh-gradient and ultra-compact particle accelerators, which could transform medicine and materials science.
Paper: TUP3014
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3014
About: Received: 11 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
TUP3016
cSTART – Status on the compact electron STorage ring for non-equilibrium Accelerator Research and Technology
1572
The goals of the cSTART storage ring at Karlsruhe Institute of Technology (KIT) are to demonstrate the storage of ultra-short electron bunches and study their non-equilibrium dynamics. Furthermore, it aims to study the application of laser-plasma accelerators (LPAs) as injectors for storage rings. To allow the direct injection of LPA bunches with comparably large energy spread, cSTART has a specifically designed flexible magnetic lattice with large momentum acceptance. The non-ramping ring will also use the existing linac-based accelerator FLUTE as injector for commissioning and experiments with controlled beam parameters. In 2024, the collaboration between KIT, RI Research Instruments GmbH, and its subcontractors completed the Technical Design Report (TDR), followed by the Final Design Report (FDR) in spring 2026. The magnets and power supplies for the injection line (IL), which will connect FLUTE to the storgae ring, are already available in KIT’s inventory. Meanwhile, the magnets, power supplies, and vacuum chambers for the storgae ring are currently in production. This contribution provides an overview of the current status an outlines the next steps of the cSTART project.
Paper: TUP3016
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3016
About: Received: 13 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
TUP3017
Towards integrated diagnostics for multi-stage dielectric laser acceleration: a conceptual study
1576
Dielectric laser acceleration (DLA) enables compact, chip-scale accelerators. Recent demonstrations of multi-stage acceleration, alternating-phase focusing and interaction length in the millimeter range in dielectric nanostructures have verified the scalability of DLA concepts but the compactness places extreme demands on beam diagnostics due to submicron apertures, sub-fs bunch lengths and strong non-linear dynamics. To support the development of multi-stage structures and precise matching between stages, we explore diagnostic concepts that use the dielectric structures themselves. Tailored gratings can encode beam properties—such as bunch length—into emitted radiation, providing compact, high-resolution, on-chip diagnostics. Additionally to these hardware approaches, we propose to apply a machine-learning–based virtual diagnostic for DLA experiments. A neural network trained on 6D tracking simulations reconstructs key interaction parameters from the post-DLA electron beam and intermediate diagnostics and enables real-time optimization even in strongly non-linear regimes. Combining integrated dielectric diagnostics with ML-based reconstruction provides a scalable strategy for precise characterization and control of next-generation dielectric laser accelerators.
Paper: TUP3017
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3017
About: Received: 13 May 2026 — Revised: 17 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP3019
Betatron radiation studies as a path to plasma undulators
1580
The emission of betatron radiation from the beam-driven plasma wakefield acceleration is under consideration at SPARC_LAB [1], as a test-bed for the study and development of a plasma-based undulator device. In the framework of the EuPRAXIA ESFRI facility [2] and EuPRAXIA@SPARC_LAB project [3], there is a deep interest in developing a compact plasma-based user facility, not only for what concerns the acceleration module, but also for what is ancillary to the delivery of FEL radiation. In this regard, great efforts have been made to miniaturize for instance diagnostic stations, detection devices and transfer lines, e.g. based on active plasma lenses [4]. However, conventional undulators are still too cumbersome and expensive to meet the requirements of compactness and sustainability. Nowadays, advanced undulator concepts arouse great interest in pushing the frontier beyond conventional, magnet-based undulators. In this regard, a promising, alternative is represented by the betatron motion of electrons in an ion-channel to emulate an undulator device. This work will present a case study at SPARC_LAB. [1] M. Ferrario et al., Nucl. Instr. and Meth. B 309, 183–188 (2013). [2] Assmann, R. W. et al., Eur. Phys. J. Spec. Top. 229, 3675–4284 (2020). [3] M. Ferrario et al., Nucl. Instr. and Meth. A 909, 134–138 (2018). [4] R. Pompili et al., Phys. Rev. Accel. Beams, 22:121302, Dec 2019.
Paper: TUP3019
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3019
About: Received: 21 May 2026 — Revised: 21 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP3021
Sub-10 fs synchronization in laser-plasma accelerators with terahertz frequency bunch manipulation
1583
There is a growing demand for generating and transporting very short femtosecond-scale, high-charge-density relativistic electron bunches [1-2]*. Applications range from extreme light sources such as free-electron lasers to future linear colliders. Laser-plasma wakefield accelerators (LWFA) [3] offer a promising approach for compact high-gradient acceleration, but electrons generated directly from the plasma in a non-linear self-injection process show poor stability and limited control. External injection [4-5] provides a solution but requires extremely short electron bunches with precise control, which is currently limited by compression and timing jitter in conventional radio-frequency accelerators [6]. We show that laser-driven terahertz (THz) control of electron bunches can enable phase-locked, laser-synchronized compression with suppressed time jitter [7]. Using computational methods, we explore the external injection of such THz-controlled electron bunches into a LWFA. By utilizing intrinsic synchronization and THz-driven energy manipulation, we demonstrate significant stabilization in external injection while preserving high bunch quality.
Paper: TUP3021
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3021
About: Received: 12 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
TUP3043
A full-energy electron injector for the EIC based on proton-driven plasma-wakefield acceleration
1612
The Electron-Ion Collider (EIC) is presently under construction at Brookhaven National Laboratory, and will collide electrons with an energy of up to 18 GeV with hadrons of up to 275 GeV. In this work we evaluate the feasibility of using proton-driven plasma wakefield acceleration to accelerate electron bunches to full energy for injection into the EIC Electron Storage Ring. Particle-in-cell simulations are used to identify a scheme which allows the acceleration of electron bunches with high charge and low energy spread, building on previous studies which investigated the potential energy gain. The RHIC “BLUE RING”, which accelerates hadrons in the same direction as the electrons of the EIC, can be exploited to drive the plasma wakefields, offering the potential to significantly reduce the capital cost of the EIC facility. We show that by increasing bunch population to $3\times 10^{11}$, and moderate compression of the drive bunch to 2.5 cm, high accelerating fields can be achieved by exploiting the self-modulation of the proton beam, as harnessed by the Advanced Wakefield Experiment (AWAKE) project at CERN. To facilitate the use of a plasma discharge, we consider the possibility of using different ions, instead of rubidium.
Paper: TUP3043
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3043
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP3044
Gaussian Process Regression and Bayesian Optimization for a 40-90 MeV Laser-Plasma Injector for the cSTART Storage Ring
1616
Laser-plasma accelerators (LPAs) generate ultrashort high intensity electron bunches from a compact source size. At the Karlsruhe Institute of Technology (KIT), we will use an LPA as one of the injectors for the compact, high-momentum acceptance, non-equilibrium storage ring cSTART. The LPA injector with a length of only a few millimeters will be optimized to match the cSTART operation beam energy of 40-90 MeV. It will be based on an ionization trapping scheme in combination with a tailored plasma density profile to produce an electron beam with small energy spread that maximizes the spectral charge density at our target energy, which is (for LPAs) comparably low. Moreover, the LPA injector must produce controlled electron beams with high shot-to-shot stability and avoid high-energy tails. These goals can be achieved largely by the detailed design of the plasma density profile and the laser pulse parameters. In an LPA, small changes across the high-dimensional parameter space can have a disproportional influence on overall performance. To find parameters for stable high-quality LPA beams, we perform particle-in-cell (PIC) simulations and implement a machine-learning driven approach by using Bayesian Optimization (BO) based on Gaussian Process Regression (GPR). This procedure allows us to both optimize our gas target design and characterize the effects of the interaction parameters, giving us a functional LPA with a simple tuning mechanism.
Paper: TUP3044
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3044
About: Received: 01 Apr 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
TUP3045
Fixed-Field alternating gradient transport line for laser-plasma accelerated electrons
1620
A transport line for laser-plasma accelerated electrons is proposed based on the fixed-field alternating gradient accelerator (FFA) concept. To accommodate the large LPA energy spread and match the beam to a transverse gradient undulator (TGU), the lattice incorporates matching cells with high-temperature superconducting quadrupoles providing gradients up to 220 T/m, along with a compact FFA dispersion creator. This configuration allows strong focusing and dispersion tailoring within a compact geometry. The study represents an initial step toward demonstrating the feasibility of FFA-based dispersion management for LPA-driven light sources, while outlining the requirements of further optimization.
Paper: TUP3045
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3045
About: Received: 11 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP3046
Laser-plasma electron injector for the cSTART storage ring
1624
Laser-plasma accelerators (LPAs) generate ultrashort, high-intensity electron bunches in a compact form factor. At Karlsruhe Institute of Technology (KIT), we are developing an LPA for direct injection into a specifically built storage ring with high momentum acceptance. The cSTART storage ring (compact storage ring for accelerator research and technology) can be tuned to energies between 50 – 90 MeV, and its lattice is designed to accept electron beams with +/- 4% energy spread. Furthermore, the ring lattice can be set up for the storage of ultrashort electron bunches. The LPA electron injector must be readily tunable to match the storage ring parameters. This contribution reports proof-of-concept experiments that demonstrate the generation of high-quality LPA electron beams with parameters that fulfill the cSTART requirements.
Paper: TUP3046
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3046
About: Received: 12 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP3049
AWAKE: preparing for physics beyond LS3
1627
The AWAKE programme at CERN has evolved from its initial proof-of-principle phase to a comprehensive facility dedicated to advancing proton-driven plasma wakefield acceleration towards first particle-physics applications. In preparation for this next stage, AWAKE will undergo a major upgrade during CERN’s Long Shutdown 3 enabling the demonstration of electron acceleration to 6-10 GeV in a 10 m plasma source with controlled beam quality and validated scalability. Meeting the targets of 5-8% energy spread, 100 pC of accelerated charge and controlled emittance requires strong beam loading. This will be provided by a new RF photo-injector system equipped with two X-band structures and an optimized transfer line, delivering 150 MeV electrons with 5.75 um beam size at injection and 2 mm mrad normalized emittance. In parallel, the 400 GeV SPS proton bunch must reach full self-modulation in the first plasma source (‘self-modulator’) before the electrons are injected into the second plasma source (‘accelerator’). Extensive infrastructure modifications are already in progress, including the dismantling of the CNGS target area in order to create the space required for the upgraded AWAKE facility. We present the consolidated roadmap, the scientific goals, upgrade status and the key challenges associated with both the facility design and the experimental programme starting in 2029.
Paper: TUP3049
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3049
About: Received: 19 Apr 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
TUP3063
Performance analysis of a Mach-Zehnder interferometer using synthetic interferograms
1639
In this work, we assess the performance and limitations of Mach-Zehnder interferometry for plasma diagnostics using a fully synthetic, numerically generated dataset. We explore regions of parameter space that are difficult to access experimentally, including fringe behaviour under different plasma density profiles, the dynamic range of measurable phase shifts, and the resolution limits for low-density plasmas. By introducing controlled phase errors and noise, we quantify the robustness of common phase retrieval and phase unwrapping algorithms and identify the conditions under which these methods succeed or fail. Our results provide practical design guidelines for optimising interferometric measurements across a wide range of plasma conditions.
Paper: TUP3063
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3063
About: Received: 12 May 2026 — Revised: 16 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
TUP3068
WarpX simulation of the plasma meniscus effect in a neutral beam injection system
1646
The US Department of Energy INFUSE collaboration between Realta Fusion and Lawrence Berkeley National Laboratory (LBNL) aims to extend WarpX towards high fidelity modeling of neutral beam injection (NBI) systems. WarpX is a parallel, open source, and portable particle-in-cell (PIC) code with an active developer community and demonstrated scalability. In this work, we implement and validate the plasma meniscus modeling for a positive ion source using first principle PIC simulations. These simulations are performed in the electrostatic mode with extraction electrodes represented as embedded boundaries. The upstream plasma reservoir is modeled using a thermal injection scheme with real electron mass to capture the correct sheath physics. These results and validations form a crucial basis for future extensions to negative ion sources and photoneutralization, enabling start to end NBI modeling within WarpX.
Paper: TUP3068
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3068
About: Received: 12 May 2026 — Revised: 17 May 2026 — Issue date: 22 May 2026
TUP3071
Optimized design of a C-band 100 MeV electron LINAC for FLASH radiotherapy
1654
Electron LINACs are key tools for radiotherapy. Conventional low-energy ones can treat only superficial tumors. Achieving Very High Energy Electrons (VHEE, >100 MeV) enables treatment of deep-seated tumors. Furthermore, electrons are well-suited for delivering Ultra-High Dose Rates (UHDR) required for FLASH therapy, which improves healthy-tissue sparing. Combining VHEE and FLASH in a hospital environment represents an important step forward for Radiotherapy. In the context of the SAFEST project at Sapienza, this work presents a compact and cost-effective accelerator layout capable of delivering hundreds of nC at 100 MeV within tens of pulses over 1 ms of irradiation. The design emphasizes efficient RF power usage through high-efficiency C-band structures and a pulse compressor. Beam dynamics simulations and low-power RF tests validate the approach. A strong focus is placed on flattening the compressor signal, which must remain stable over 1 mus to accommodate electrons from a triode thermionic gun, a compact and economical source for this accelerator. The resulting 3-m linac, powered by a single 20-MW klystron, shows strong potential for future hospital-based FLASH VHEE treatments.
Paper: TUP3071
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3071
About: Received: 15 Apr 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP3073
Study and test of a triode gun for the FLASH electron LINAC at Sapienza
1658
A 24-MeV prototype LINAC is under development at Sapienza University of Rome for FLASH radiobiological studies. The injector is a 12-keV triode thermionic electron gun from HeatWave Labs, providing grid-controlled current modulation for high current, low perveance, and short-pulse operation. To optimize its integration with the 24 MeV C-band hybrid standing and travelling wave structure, extensive particle tracking simulations of electron gun were performed using CST Particle Studio. Parametric scans of the anode voltage and grid potential were used to evaluate beam current, perveance, and emittance, identifying operating points that balance beam stability and charge for FLASH applications. As the modern dispenser cathode requires stringent vacuum conditions below 1E-6 mbar, the LINAC was also modeled in Molflow+ to predict pressure profiles under realistic gas-load scenarios. Simulations revealed a potential vacuum limitation near the gun, leading to the design and implementation of an additional pumping port for better evacuation of gas molecules. These results are benchmarked with initial experimental tests performed on an electron gun test bench at Sordina IORT Technologies and with Flash LINAC at the department of Basic and Applied Sciences for Engineering in Sapienza. The combined simulation and experimental validation provides key requirements of an injector for a compact commercial LINACs for Flash applications.
Paper: TUP3073
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3073
About: Received: 11 May 2026 — Revised: 16 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
TUP3074
RF design of the 1 kHz photoinjector for the RUEDI Electron Diffraction Facility
1662
The RUEDI RF photoinjector will have a 2.4 cell S-band gun producing electrons at 4 MeV. The gun is designed to operate at 1 kHz repetition rate. This will be achieved by a combination of RF over-coupling to reduce the pulse length, and an advanced water cooling system based on that of the CLARA 400 Hz photoinjector. The shorter pulse length is also intended to limit the dark current, along with operation at 70 MV/m, and the flat back plate cathode. The cell lengths are optimised to improve jitter cancellation performance, as well as to limit surface electric fields on the irises. The cavity is dual side-coupled into the middle cell with a racetrack coupling cell to reduce the quadrupole component, and has an RF probe on the final cell.
Paper: TUP3074
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3074
About: Received: 15 Apr 2026 — Revised: 27 Apr 2026 — Accepted: 14 May 2026 — Issue date: 22 May 2026
TUP3075
Evidence for RF breakdowns causing surface anomalies on caesium Telluride cathodes at Clara
1666
The Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury Laboratory has recently undertaken an upgrade of its photocathodes from using a copper emission surface to using caesium telluride (Cs\textsubscript{2}Te). During the conditioning of the first Cs\textsubscript{2}Te cathode a significant number of RF breakdowns were detected, and so that cathode was replaced; subsequent inspection of the cathode following removal identified a number of surface defects. To better study the second cathode, a diagnostic camera was used to collect images of the surface \textit{in situ} during RF conditioning; the frequent formation over time of surface defects was observed. In this paper we present a statistical analysis of the breakdown events and surface image data, utilizing cross-correlation of the signal derivatives to account for cumulative trends. The analysis reveals a correlation between the rate of defect formation and the incidence of RF breakdowns, with a Pearson coefficient of $r = 0.59$ at zero time lag. These results provide quantitative evidence that RF breakdown events are the likely driver of surface morphology changes on Cs\textsubscript{2}Te cathodes.
Paper: TUP3075
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3075
About: Received: 15 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
TUP3076
Recent dark current measurements on the CLARA S-band RF electron guns
1670
The CLARA accelerator at Daresbury Laboratory has recently commissioned a new electron gun as part of a larger upgrade to the machine. The new gun (‘HRRG’) is a high rep rate (400 Hz) 1.5 cell cavity (3 GHz fundamental frequency) designed to produce low emittance beams up to 5 MeV/c, with cathode fields up to 120 MV/m and RF pulse lengths of up to 3 us. The previous CLARA gun (‘LRRG’) was a similar 2.5 cell device but low rep rate (10 Hz). Dark current emitted from the gun is an important issue for several reasons, so is monitored and managed throughout CLARA commissioning and user operation. We present results from the dark current measurements from the new HRRG gun through its commissioning and early stage operation, and make a comparison to those taken from the previous LRRG gun.
Paper: TUP3076
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3076
About: Received: 16 Apr 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP3078
Laser wakefield acceleration in carbon nanotube bundles
1674
Laser wakefield acceleration (LWFA) can produce accelerating fields of several hundred GV/m, greatly reducing accelerator size and cost. Carbon nanotube (CNT) bundles, featuring high plasma density (>10$^{19}$ cm$^{-3}$), tunable effective density, excellent thermal properties, and empty channels that enable laser propagation, have attracted interest as solid-state plasma sources. Previous studies suggested that CNT-based structures can increase the acceleration field to the TV/m range, making them promising for compact radiation sources and radiotherapy. However, the insufficient beam quality still limits their broader application. In this work, we model a hollow solid-state plasma channel composed of CNT bundles. A 2 PW laser from the ELI-ALPS High-Field Laser facility is injected into the channel, where self-injected electrons at the nC-scale are trapped and accelerated in a TV/m field, as shown by particle-in-cell simulations with WarpX. Comparing with previous LWFA results using solid-state targets, we obtain an electron beam with > 2 nC charge and > 100 MeV mean energy, while achieving an unprecedented energy spread < 5%, by tuning the filling factor, bundle diameter, and gap size. We clarify that the large energy spread in the overdense plasma arises from the laser-plasma instability. In addition, we observe strong scattering within the overdense bundle walls. We further aim to investigate how the scattering affects the laser field and, consequently, the beam quality.
Paper: TUP3078
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3078
About: Received: 11 May 2026 — Revised: 20 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP3081
Shielding calculations and activation studies for the PSI Positron Production experiment
1681
The Future Circular Electron-Positron Collider (FCC-ee) is a proposed next-generation particle accelerator, planned as the first stage of the larger Future Circular Collider project at CERN. It is an electron-positron collider designed to be a precision instrument for studying fundamental physics. The PSI Positron Production (P$^{3}$) is the planned proof-of-principle experiment for the FCC-ee positron source. The main goal of this experiment is to test new technology and validate the envisioned positron production scheme. To this end, a prototype of the FCC-ee positron source will be hosted at the SwissFEL facility at the Paul Scherrer Institute in Switzerland. A dedicated bunker has been built inside the SwissFEL tunnel, and the experimental components are being installed. Simulations have been performed with the FLUKA.CERN Monte Carlo code to dimension the P$^{3}$ bunker and local shielding elements. Calculations have been repeated for various target models since different target options will be tested. This contribution briefly describes the ingredients of the P$^{3}$ experiment and details the dedicated bunker and the local shielding. It shows the expected dose rate distribution outside the P$^{3}$ bunker. The foreseen activation is also discussed.
Paper: TUP3081
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3081
About: Received: 12 May 2026 — Revised: 14 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP5301
Beam performance of the positron transport line for CEBAF positron upgrade
1685
The Low Energy Recirculator Facility (LERF) at Jefferson Lab, formerly operated for the Free-Electron Laser program, has been proposed as the injector complex for the planned 12 GeV CEBAF positron upgrade (Ce+BAF), with an additional pathway to support a potential 22 GeV CEBAF electron upgrade. In this configuration, LERF would generate and pre-accelerate positrons to 123 MeV, matching the present injection energy into the North Linac. Due to the relatively large emittance expected from the positron source, a comprehensive acceptance study has been performed from LERF through the CEBAF recirculating linacs and beam transport lines to the experimental halls. The objective is to establish the positron phase-space acceptance and provide design feedback to the positron production and capture systems. Furthermore, given CEBAF’s capability to deliver highly polarized beams, spin-tracking simulations have been carried out including magnet imperfections, alignment errors, and synchrotron-radiation–induced energy spread. Particular attention is given to the evolution of the spin tune and the corresponding depolarization mechanisms along the beam delivery path, especially for providing longitudinal polarization at the experimental halls. These results inform injector design choices and assess the overall feasibility of delivering high-polarization positron beams in CEBAF.
Paper: TUP5301
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP5301
About: Received: 11 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
TUP7622
Design of a compact energy-tunable X-band linac for FLASH radiotherapy
1820
FLASH radiotherapy (FLASH-RT) demonstrates the potential to maintain tumor control while reducing normal tissue toxicity through ultra-high dose rates. This paper presents a novel compact X-band (9.3 GHz) accelerating system designed for FLASH-RT applications. The core innovation is a dual-structure common-source architecture: the first structure provides a fixed 6 MeV energy gain, while the second enables independent continuous energy adjustment from 0 to 6 MeV via a tunable microwave network. This design allows a single klystron to drive both structures without mutual interference during energy adjustment. The system length is only approximately 1 meter. The design process integrates radio frequency (RF) simulation and beam dynamics simulation in a coupled manner, with particular focus on the bunching section optimization. This compact system provides a high-performance accelerator solution for next-generation FLASH radiotherapy, especially for intraoperative applications requiring rapid energy adjustment.
Paper: TUP7622
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7622
About: Received: 10 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP7626
Design and construction of a HOM-damped TM020 type harmonic cavity for luminosity enhancement in RI-electron scattering
1834
The RIKEN SCRIT facility that involves an electron storage ring (SR2) is a dedicated RI-electron scattering experiment. In the SCRIT system, the target RI ions are confined at high density on the beam axis by the focusing force provided by the electron beam itself. Therefore, electron beam stability is essential to increase the luminosity and maintain it for a sufficient time during scattering experiments. Since the current RF cavity induces beam instabilities due to higher order modes (HOM), a new HOM damped cavity is being designed and constructed and will soon be replaced. Here, we adopted the TM020 type harmonic cavity, which has recently been developed and first practically used at the NanoTerasu synchrotron light source. The cavity has coaxial slots at both the front and rear ends with ferrite absorbers inside. It is a very simple and compact design, yet it efficiently damps most resonant modes except for the TM020 mode. The design frequency of the TM020 is 956.220 MHz, which is the fifth harmonic of the current drive frequency 191.244 MHz, and accordingly the harmonic number in SR2 is changed from 14 to 70. As revealing from simulation studies, an increase in the harmonic number makes the trapping lifetime of the target RI ions longer, and this effect, coupled with the stabilization due to the disappearance of HOMs, is expected to significantly improve the luminosity performance in RI electron scattering.
Paper: TUP7626
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7626
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP7640
Design and vertical test of a passive 3rd harmonic superconducting cavity for HALF storage ring
1868
A 3rd harmonic superconducting (SC) cavity is being developed for lengthening bunch and improving beam lifetime in the Hefei Advanced Light Facility (HALF) storage ring. This SC cavity is excited by an electron beam with 350 mA current, 1 nC charge, and ~6.7 ps length and requires strong damping of higher-order-modes (HOMs) in order to meet beam instability requirements. This paper presents design and vertical test of this passive 3rd harmonic SC cavity in detail. The vertical test results indicate that the cavity accelerating voltage reaches as high as 1.5 MV with the quality factor better than 3.4E8 and there is no multipacting or field emission.
Paper: TUP7640
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7640
About: Received: 13 May 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP7641
Ground-state and RF-frequency scaling for superconducting quantum systems
1871
A fixed-volume comparison of three-dimensional hard-wall quantum confinement is extended to a volume-dependent frequency model for superconducting quantum systems. The equivalent quantum frequency is obtained from the lowest Dirichlet eigenvalue and compared with radio-frequency (RF) scales used in supercon-ducting radio-frequency (SRF) cavities. The calculation separates the Schrödinger confinement scale from the electromagnetic wavelength scale: the quantum frequency follows an inverse two-thirds volume law, whereas a dimensional RF half-wave scale based on L = V¹ᐟ³ follows an inverse one-third volume law. Equating the two frequencies maps MHz-to-GHz SRF operation to submicron-to-micron local confinement lengths, supporting applications to superconducting islands, surface defects, qua-siparticle traps, and cavity-integrated quantum devices.cavity systems.
Paper: TUP7641
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7641
About: Received: 07 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
TUP7647
Current status of the upgrade and operation of the NSRRC TPS linac pulse high-power RF System
1882
The NSRRC Taiwan Photon Source (TPS) LINAC system consists of a DC thermionic electron gun, a Sub-Harmonic Pre-Buncher, a Primary Buncher, a Final Buncher, three S-band LINAC sections, and three 35-MW S-band klystrons. The TPS LINAC was designed by Research Instruments (RI). In the original design, the S-band klystrons were Thales TH2100A tubes. Due to unstable production quality in recent years and the resulting reduction in tube lifetime, NSRRC initiated a klystron upgrade program to replace the TH2100A with the E37310A klystron manufactured by CETD. The primary objective of this work is to analyze the RI-designed LINAC system and complete the necessary modification design so that it can operate with the CETD E37310A klystron and supply the required RF power. Leveraging the technology and experience gained from the in-house development of the THz FEL pulse RF system, NSRRC successfully upgraded the Taiwan Light Source LINAC pulse RF system in August 2023. After six months of stable operation, planning for upgrading the three TPS LINAC pulse RF systems began in 2024. Compared with the TLS system, the RI turnkey LINAC is more complex and requires additional study to support an in-house upgrade. This paper presents the upgrade work and results of the first and second TPS LINAC pulse RF systems completed in September 2025 and January 2026, including system installation, modulator modification design, testing results, and current operational status.
Paper: TUP7647
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7647
About: Received: 11 May 2026 — Revised: 18 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
TUP7680
Investigation on the vacuum properties of Al-TiZrV bilayer films
1937
Maintaining an ultra-high vacuum (UHV) environment is essential for the Hefei Advanced Light Facility (HALF) to achieve its design performance. Owing to the dimensional limitations imposed by small-aperture vacuum chambers, non-evaporable getter (NEG) films are commonly applied to the inner walls to enhance vacuum performance. However, conventional NEG films increase the resistive-wall impedance of the vacuum pipes, there-by exacerbating the wakefield effects. To address this problem, a novel composite film, Al-TiZrV, has been developed. By covering the TiZrV film surface with a highly conductive film, it can reduce the resistivity of the composite film. The results show that while the addition of the Al layer reduces the resistivity significantly, it increases the secondary electron yield (SEY), exacerbating the electron cloud effect. This study provides insights into the complex properties of similar bilayer films for future research on accelerator-related materials.
Paper: TUP7680
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7680
About: Received: 15 Apr 2026 — Revised: 29 Apr 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
TUP7683
Study on the vacuum properties of Pd/Ti bilayer thin films
1943
Non-evaporable getter (NEG) thin films are essential for achieving ultra-high vacuum in the narrow-bore chambers. Pd/Ti bilayer NEG thin films were deposited on oxygen-free copper and silicon substrates by DC magnetron sputtering. The microstructure and elemental distribution were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The films exhibit a cauliflower-like surface morphology and a columnar cross-sectional structure, providing a high specific surface area and effective pathways for gas diffusion. The pumping speed for H$_2$ was evaluated using the constant-pressure dynamic flow method after activation at 150 °C for 12 h. The pumping speed decreases from 0.13 to 0.02 L s$^{-1}$ within a pumped quantity range of $1 \times 10^{-5}$ - $6.5 \times 10^{-3}$ Pa L. A non-monotonic variation in pumping speed was observed, which is attributed to hydrogen adsorption, dissociation on the Pd surface, and subsequent diffusion into the Ti layer for hydride formation. The results demonstrate that the Pd overlayer effectively enables low-temperature activation and enhances hydrogen sorption behavior, indicating that Pd/Ti NEG thin films are promising candidates for ultra-high vacuum applications in accelerator systems.
Paper: TUP7683
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7683
About: Received: 15 Apr 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP7693
Current status of TPS vacuum system
1960
The TPS is currently operating at a beam current of 500 mA for users. Until now, 17 insertion devices have been installed in the straight vacuum sections, and the associated vacuum components have been upgraded. The average vacuum pressure of the storage ring is 8.5 nPa, and the beam lifetime under 500 mA operation is approximately 6 hours. The behavior of vacuum readings, the pressure distribution and the related interlock will be discussed in this paper.
Paper: TUP7693
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7693
About: Received: 13 May 2026 — Revised: 17 May 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
TUP7698
Analysis and refurbishment of a radiation-damaged undulator
1971
Synchrotron radiation facilities impose stringent requirements on the magnetic field quality, stability, and lifetime of undulators. During long-term operation of a beamline at the Shanghai Synchrotron Radiation Facility (SSRF), a gradual degradation of photon-beam performance was observed. To identify the cause, the cryogenic permanent magnet undulator of this beamline was warmed up and re-measured at room temperature during the summer shutdown. The on-axis field was found to be most strongly attenuated in the upstream region, with a maximum reduction of about 20% that gradually relaxed towards the downstream end. In addition, several sharp local drops of the magnetic field were detected in the central section. Visual inspection revealed pronounced melting holes in the copper foil in this area, indicating localized electron-beam impacts that likely damaged the underlying magnets and led to the abnormal field reduction. This paper presents the magnetic measurement results and the longitudinal attenuation pattern of the radiation-damaged undulator, and describes how local magnet replacement, re-shimming, and re-measurement were used to refurbish the device, providing a reference for future operation, maintenance, and radiation-protection design of similar undulators.
Paper: TUP7698
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7698
About: Received: 15 Apr 2026 — Revised: 16 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
TUP7699
Design of a Compact Hybrid Planar Undulator
1974
Undulators are key insertion devices in synchrotron radiation and free-electron laser (FEL) facilities, where shortening the magnetic period is a crucial technical route to achieving compact machines and short-wavelength radiation. In our previous work, we proposed and experimentally validated an ultra-compact planar undulator that provides about a 48% increase in magnetic field strength compared with a conventional planar undulator under the same period length and gap, but its field strength is fixed and not tunable, limiting its engineering applicability. Building on that work, this paper proposes a compact hybrid planar undulator design that deliberately sacrifices part of the magnetic field strength to achieve tunability over a practical working gap range. To reduce the demagnetizing field experienced by the magnets under operating conditions, permanent magnets with different grades are combined in the structure, effectively mitigating the demagnetization risk in critical regions. Using three-dimensional magnetic-field simulations and optimization, we systematically investigate the effective field, field roll-off characteristics, and integrated field errors. The results show that the proposed compact hybrid planar undulator maintains a short period and relatively high field strength while providing magnetic-field tunability, offering a useful reference for the design of next-generation compact, high-performance undulators for advanced light sources.
Paper: TUP7699
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7699
About: Received: 15 Apr 2026 — Revised: 30 Apr 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
TUP7709
Design and experiment of energy feedback unit for 15 kV/15 kA AMD excitation pulse source
1988
Abstract: The Super Taume-Charm Facility (STCF), a new generation of electron-positron collider led by the University of Science and Technology of China, requires a high-quality positron source to sustain high-luminosity continuous operation. The Adiabatic Matching Device (AMD) is a critical component for positron focusing, its excitation pulse source requires a peak current ≥15 kA and a pulse front edge ≤3.5 us. To reduce the significant power dissipation of pulse discharge system, an energy feedback circuit was designed. The optimized system achieved a dramatic reduction in losses, decreasing input power by 73.96% and enhancing long-term operational stability. This article provides a detailed account of the simulation of power loss in AMD excitation pulse sources, as well as the design, simulation, and offline debugging of energy feedback circuits. Key words: excitation pulse power for AMD; power loss; energy feedback; photoconductive semiconductor switch
Paper: TUP7709
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7709
About: Received: 15 Apr 2026 — Revised: 14 May 2026 — Accepted: 14 May 2026 — Issue date: 22 May 2026
TUP7719
Beam dump design and simulation for a 280-MeV electron linear accelerator
2004
A 280-MeV electron linear accelerator has been designed to expand the research capabilities and applications of high-energy electron beams in Thailand. For commissioning and energy verification, two dedicated beam dumps are positioned downstream of the bending magnet. This work presents the simulation-based design and optimization of these beam dumps using the PHITS Monte Carlo radiation transport code. Different material configurations and geometries were evaluated to reduce prompt radiation and suppress secondary particle leakage. A multilayer structure combining high-Z and low-Z materials was found to provide effective energy absorption while confining photon and neutron secondaries within the shielding volume. The resulting radiation field in the tunnel meets all applicable safety criteria and regulatory limits. These results establish the validated baseline design for the beam dumps and support their transition to detailed engineering and fabrication.
Paper: TUP7719
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP7719
About: Received: 03 May 2026 — Revised: 19 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
TUP8002
Compact X-Band Linear Accelerators Design for On-Site Industrial Applications
2039
The progressive replacement of radioactive sources is stimulating growing interest in compact linear accelerators, which are better suited for field deployment. Such systems must emphasize modularity, transportability, and, above all, reliable performance under operational conditions. This work introduces a family of compact X-band linear accelerators designed to produce electron beams in the low-MeV energy. The engineering design focuses on the key component: the accelerator structure. A biperiodic on-axis coupled standing-wave structure was selected, operating in $\pi/2$ mode. Simulation results demonstrate that the proposed configurations achieve the targeted energy levels with controlled beam transmission, while providing a focal spot size (FWHM) below 1 mm, significantly outperforming conventional radioactive sources ($\approx 5$ mm). This paper summarizes the overall design approach, highlights the main simulation results, and outlines the current progress of development activities.
Paper: TUP8002
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP8002
About: Received: 15 Apr 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP8008
Ultra-high dose-rate irradiation experiments at FLUTE
2049
The linac-based test facility FLUTE at the Karlsruhe Institute of Technology (KIT) can be operated with a wide range of beam parameters, such as bunch charge, bunch length and repetition rate. This flexibility makes FLUTE an interesting test-bed for studies of accelerator-based ultra-high dose-rate irradiation with electron beams. Based on the time structure of the produced electron pulses, the instantaneous dose-rate can be tuned to exceed $10^{11}$ Gy/s with an average dose rate exceeding 40 Gy/s. At the same time, FLUTE can also provide average dose-rates closer to conventional rates in the order of 0.1 Gy/s.
Paper: TUP8008
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP8008
About: Received: 11 May 2026 — Revised: 17 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP8009
Advancements and dosimetry of a single-turn extraction for FLASH radiotherapy studies at ELSA
2053
Ultra-high-energy electrons are used to investigate their effects on cell samples in nanosecond to microsecond pulses at the electron accelerator facility ELSA. This may allow highly efficient treatment of deep-seated tumors through the FLASH effect. Previous studies at ELSA using an inital extraction mode with 250 ns long pulses from the 1.2 GeV booster synchrotron demonstrated the suitability for FLASH radiotherapy studies. A newly developed single-turn extraction scheme from the stretcher ring now enables access to beam energies of up to 3.2 GeV with pulse lengths of approximately 330 ns and improved beam stability. In preparation for upcoming cell irradiation studies with this new extraction mode, precise dose determination is carried out by combining radiochromic film measurements with Geant4 simulations over the full energy range from 1.2 GeV to 3.2 GeV. Depth-dose curves from the previous and current operation modes are compared. Additionally, studies of Cherenkov radiation are performed to evaluate its potential for beam characterization.
Paper: TUP8009
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP8009
About: Received: 12 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
TUP8014
ATSOA at CERN: A Hands On Accelerator Course in the EURO-LABS Framework
2060
Beyond providing Transnational Access to major Research Infrastructures (RIs) across Europe, the European Laboratories for Accelerator Sciences (EURO-LABS) programme supports advanced training activities. Within this framework, an Advanced Training School on the Operation of Accelerators (ATSOA) is organised at CERN. The school targets students, young researchers, and professionals in the field of accelerator science, offering them a unique opportunity to participate in a week of hands-on training. Five CERN facilities — CLEAR, AD/ELENA, ISOLDE, PSB and LEIR — are involved in the training, allowing participants to familiarise themselves with different accelerator types and particle species. Under the guidance of experienced instructors, they carry out dedicated experiments designed to illustrate key physics concepts and operational principles that can be applied in their own work. This contribution gives an overview of the past schools and an outlook for future courses.
Paper: TUP8014
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP8014
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP8016
Development of VHEE Scattering Systems for FLASH Radiotherapy
2064
Very High Energy Electrons (VHEE) are an emerging radiotherapy modality offering magnetic steering and focusing for conformal treatments, with potential for compact, cost-efficient clinical systems. VHEE beams may also enable Ultra-High Dose Rate (UHDR) delivery for the FLASH effect, which can selectively spare healthy tissue while maintaining tumour toxicity. A key challenge is achieving transversely uniform VHEE dose at UHDR, as current magnets cannot scan large tumour volumes within FLASH timescales (~0.1 s). Conventional dual-scattering systems—using a pre-scatterer for magnification and a Gaussian scatterer for flattening—are unsuitable at VHEE energies, generating substantial photon contamination unless the beamline is greatly extended. This work replaces the pre-scatterer with a quadrupole lattice that magnetically enlarges the beam while reducing Bremsstrahlung. RF-Track and TOPAS simulations show that an optimised quadrupole-scatterer design produces a 75 mm uniform field and reduces photon yield by 94.5% compared with dual-scattering. BDSIM confirms the modelling. Experimental validation at CLEAR at CERN is in preparation, and an optimiser is being developed to design quad-scatterer systems for generic VHEE machines using existing quadrupoles. These results suggest that magnetic beam magnification upstream of a Gaussian scatterer is a promising route to FLASH-compatible VHEE therapy with reduced secondary radiation and improved dose conformity.
Paper: TUP8016
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP8016
About: Received: 16 Apr 2026 — Revised: 20 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP8018
A Status update of LhARA, an Accelerator-driven Radiobiology Research Initiative
2068
LhARA is multidisciplinary collaboration that is embarking on an initiative to use laser-driven ions in a hybrid acceleration scheme with a fixed-field alternating gradient (FFA) accelerator to deliver a systematic radiation biology programme and lay the technological foundations for the transformation of proton and ion beam therapy. LhARA is in an R&D phase of activity that is overseeing the development of a number of accelerator technologies to support our initiative, as well as conducting experiments in the Proof-of-Principle for LhARA and Radiobiology (PoPLaR) programme that is examining the effect of laser-driven ions on biological tissue samples. Here, we present a summary of the most recent updates from the LhARA collaboration, including Gabor plasma lenses for beam capture and focusing, magnetic beam delivery schemes for variably-sized, transversely uniform beam profiles, the FFA in LhARA’s second stage to reach clinically relevant ion energies, and an overview of the PoPLaR experiment.
Paper: TUP8018
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP8018
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUP8027
Estimation of Radiation Field for BDF/SHiP at CERN
2072
The Beam Dump Facility (BDF) will host the Search for Hidden Particles (SHiP) experiment at CERN’s Super Proton Synchrotron. BDF/SHiP is designed to search for feebly interacting particles in a region of mass and coupling accessible only with a dedicated beam-dump configuration*. With a beam intensity of 4E19 POT per year at 400 GeV, the High-Intensity ECN3 (HI-ECN3) Project will enable the search for feebly interacting particles, but the radation field created has the potential to be used parasitically to broaden the physics programme to nuclear astrophysics, materials science, and radiation-to-electronics research. High-momentum protons impinging on a tungsten target generate an intense radiation field leading to cumulative and single-event effects. In this work, the radiation environment and its impact on electronics of the detectors and associated infrastructure were evaluated through simulations performed with FLUKA Monte Carlo code. The results show that proposed optimisation solutions for shielding reduce radiation levels, keeping most effects within acceptable limits. It is also observed that modifications made to the magnetic field and geometry of the muon shield—which controls the deflection of muons produced in the beam dump to reduce flux reaching the detector—influence muon and neutrino backgrounds.
Paper: TUP8027
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP8027
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
TUV2601
Commissioning and initial operation of a Compact FEL-THz facility at IUAC, New Delhi
2101
A compact THz facility, based on Free Electron Laser (FEL) system has been commissioned at Inter University Accelerator Centre (IUAC), New Delhi. The design of the facility is based on pre-bunched FEL where a train of electron micro-bunches having maximum energy of 8 MeV are intended to be injected into a short undulator to produce the THz radiation in the range of 0.18 - 3.0 THz. The electron micro bunches are produced from the photocathode by striking with the ultra-short laser pulses generated from an advanced Fibre laser system. The frequency of THz can be tuned by varying the separation of the laser micro-pulses which produce the electron micro-bunches with variable separation. The electron micro-bunches are being injected in to the undulator to produce the THz radiation and the electron beam along with the THz radiation are co-propagating through the undulator. At the exit of the undulator, a thin Titanium foil is kept through which the electron beam passes through and the THz radiation gets reflected, subsequently detected by the Schottky Barrier Diode detector. The commissioning details and the initial operation of the of the various sub-systems of the compact FEL-THz facility e.g. high-power RF systems, electron gun, fibre laser system, state of the art photocathode deposition system, undulator, various beam transport and beam diagnostic systems, etc. will be presented in this paper.
Paper: TUV2601
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUV2601
About: Received: 15 Apr 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEO1T02
Performance Strategy for the First Years of the EIC Science Program
2138
The Electron-Ion Collider (EIC) will begin science operations with a staged machine configuration that imposes well-defined accelerator-physics constraints on achievable luminosity and beam parameters. This paper presents the performance strategy that supports the first 3-5 years of the EIC Science Program. We outline the accelerator-physics activities required to deliver high-repetition-rate electron beams, heavy-ion beams, deuterium, polarized protons, and ³He, together with the performance evolution of electron and hadron polarization systems, spin rotators, bunch patterns, and longitudinal emittance control. The paper highlights the year-by-year integration of new machine capabilities, including progressive increases in beam intensity and average luminosity required to meet evolving science objectives. This framework defines the accelerator-physics roadmap for performance delivery and sustained operation of the EIC Science Program.
Paper: WEO1T02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEO1T02
About: Received: 17 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
WEO3T02
Short-pulse driven photogun for very hard x-ray free-electron laser
2154
High gradient radio frequency (rf) driven photoguns are photoemission electron sources that have important applications for accelerator-based instruments, such as light sources and electron microscopy. Numerous efforts have been made to push for even higher field gradient while suppressing rf breakdowns. We propose the Compressed Ultrashort Pulse Injector Demonstrator, a 1.6 cell photogun driven by nanosecond high power rf pulses to achieve high gradients with low breakdown rate. This photogun is powered by ultrashort pulses from a rf pulse compressor and a high power klystron. This presentation focuses on the work of the CUPID photogun for generating bright electron beams to drive x-ray free-electron lasers (FELs) at 40 keV photons or higher. We first show the design of CUPID photogun, followed by its capability of bright beam generation when forming a photoinjector with a superconducting solenoid and downstream linacs. We then show start-to-end simulations of the existing LCLS copper accelerator free-electron laser with CUPID photogun as a drop-in replacement to demonstrate its improvement in delivering hard x-rays at mJ level pulse energy. Finally, we show preliminary high power rf testing of CUPID prototypes and plans for electron beam generation.
Paper: WEO3T02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEO3T02
About: Received: 09 May 2026 — Revised: 16 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
WEO3T03
A Portable Muon Source for artificial muon muography
2158
Muography is a useful technology for non-destructive inspection of a large-scale structure. Muography with cosmic ray muons has limitations such as low rates, particularly low muon rates in the horizontal direction, and energy spreading, which require long observation times and limit its resolution. Worldwide, large structures such as bridges built during the economic development period of the 1950s-1960s have reached the end of their useful life, and the principle of preventive maintenance is being applied to save the resources, by understanding their interiors and renewing them with priority given to structures that have deteriorated. At this time, a technology of non-destructive inspection applicable to such large structures is required, and Muography using a portable artificial muons source is a promising candidate for this purpose. In this presentation, the results of the investigation of the portable artificial muon source will be presented.
Paper: WEO3T03
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEO3T03
About: Received: 16 Apr 2026 — Revised: 19 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEO3T04
Progress Towards High-Repetition-Rate Plasma Wakefield Acceleration at FLASHForward
2163
Radiofrequency linacs accelerate thousands of bunches per second, which should be matched by beam-driven plasma wakefield accelerators (PWFAs) if their benefits as high-acceleration-gradient energy boosters are to be fully exploited. However, demonstrations to date have accelerated only ~10 bunches per second. At FLASHForward, key issues are being solved to bridge this gap. Analytic models have been developed to show how to generate bunch pairs from the photocathode with the longitudinal shape optimised for plasma acceleration, thus reducing stray radiation compared to a collimator system. To deal with large energy depositions from rapid plasma creation and acceleration events benchmarked models have been built to determine the heating of the plasma source at kHz repetition rates, so that remedial measures can be developed. Furthermore, we have seen that ionisation induced by the wakefield-perturbed plasma can limit the maximum repetition rate. Finally, PWFAs must produce large energy gains for photon science or particle physics applications. We recently demonstrated acceleration of bunches from 1.2 to > 1.7 GeV over 0.5 m of plasma, with < 2% energy spread.
Paper: WEO3T04
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEO3T04
About: Received: 01 Apr 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
WEP1014
An Updated Assessment of the Electron Cloud Effects in the Damping Ring of the FCC-ee Injector Complex
2227
The new FCC-ee injector complex design, as outlined in the feasibility report, consists of an electron source, two separate linacs for electron and positron beams to accelerate beams up to 2.86 GeV, a positron production target, a damping ring at 2.86 GeV energy for emittance cooling, a bunch compressor, a high energy linac to accelerate the beam up to 20 GeV, and an energy compressor. The primary function of the damping ring design is to accept the 2.86 GeV positron and electron beams coming from the electron linacs, reduce their beam emittances, and deliver the required beam quality for injection into the subsequent high-energy linac. It is essential for decreasing the emittance of the incoming positron beam from 2.36x10^-6 m.rad to about 1.8x10^-9 m.rad. Among the collective effects that may limit the performance of the positron rings, the electron cloud (e-cloud) effect remains one of the most significant challenges. This paper presents the results of updated studies of the e-cloud impact on various damping ring design options for the FCC-ee, including the latest version.
Paper: WEP1014
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1014
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEP1307
Hadron Storage Ring Spin Rotators & Spin Tune Compensation
2251
The Electron Ion Collider (EIC) calls for collisions of longitudinally polarized protons and helium-3 on electrons. The polarized hadron beams will be accel- erated and stored in the Hadron Storage Ring (HSR). To achieve longitudinal polarization at the interaction point (IP), spin rotators are placed on either side of the IP at 35.28 and -61.35 mrad. Due to the asymmetry of the rotators, their ramping and use will result in a shift of νs from 1/2. The HSR has six snakes that can be used to compensate for the ∆νs. The planned storage energies for protons are 41, 100, and 275 GeV, and for helium-3 are 41, 100, and 183 GeV/u. The updated rotator currents at each of these energies is provided, in addition to the ∆νs and the compensation requirements of the snakes.
Paper: WEP1307
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1307
About: Received: 12 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP1318
Progress of the RF Systems for the Electron-Ion Collider
2269
The Electron-Ion Collider (EIC) under construction at Brookhaven National Laboratory (BNL) is being developed in partnership with DOE’s Thomas Jefferson National Accelerator Facility. The EIC will deliver high-luminosity, variable center-of-mass energy collisions of highly polarized electron beams with highly polarized proton beams and ion beams. RF Systems for the EIC provide a variety of functions and operate across a wide range of frequencies, utilizing multiple cavity types. This talk will discuss the challenges and proposed solutions for the EIC RF systems, review the progress, and overview our plans for the RF Systems of the Accelerator Storage Rings.
Paper: WEP1318
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1318
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP1332
Design and Recent Developments of the Electron Storage Ring for the Electron-Ion Collider
2287
The Electron-Ion Collider (EIC), which is currently being designed for construction at Brookhaven National Laboratory, will collide polarized electron beams (5-18 GeV) with polarized hadron beams (41-275 GeV for protons) at luminosities up to $10^{34} \textrm{cm}^{-2} \textrm{s}^{-1}$ in a 3.8-kilometer ring. The EIC will be the only lepton-hadron collider since HERA at DESY and, in contrast to that earlier machine, will feature high polarization of both electrons and protons, a wide range of center-of-mass collision energies, a wide range of ion species, and much higher luminosities. These properties will make it an ideal machine for exploring the mass and spin dynamics of nucleons. The Electron Storage Ring (ESR) will be built in the existing 3.8-kilometer RHIC tunnel using normal-conducting magnets and a few superconducting magnets for the final-focus quadrupoles and spin-rotator solenoids. The wide range of energies, high polarization, high current, large beam-beam parameters, and stringent geometric constraints make the ESR a particularly challenging machine. Lately, the design of the ESR has advanced considerably with design alternatives and upgrade paths being considered to align with the key deliverables and funding profile of the project. This contribution highlights some of the important recent developments and design studies.
Paper: WEP1332
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1332
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP1340
Orbit Correction Studies on The Electron Transport Line from RCS to ESR
2295
A dedicated electron transfer line from Rapid Cycling Synchrotron (RCS) to Electron Storage Ring (ESR), referred to as the RTE line has been designed for the Electron-Ion Collider (EIC). The beamline follows a straight-line geometry, with a length of 133 m, and is consists with two matching sections and a FODO section for beam diagnostics. Imperfections with magnet alignments introduce orbit distortions, making orbit correction scheme a critical component in the design. To facilitate orbit correction, each quadrupole magnet is equipped with a pair of beam position monitors (BPMs) and kickers. The Singular Value Decomposition (SVD) algorithm is used for orbit correction and tolerance studies. This paper presents the ongoing progress in the optics design and error correction scheme of the RTE line.
Paper: WEP1340
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1340
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP1352
High-Average-Current, High-Brightness HVDC Electron Gun development for EIC Hadron Cooling
2314
The hadron cooler is an essential system for achieving high luminosity in the Electron-Ion Collider (EIC). The required electron source parameters exceed the current state of the art. We are conducting an electron-source R&D program aimed at producing an average current above 75 mA with bunch charges of 1–3 nC. This proceeding outlines the high-voltage design of a DC gun operating at 500 kV, with conditioning capability up to 600 kV. The design incorporates several unique features, including an inverted ceramic insulator at this voltage level, active cathode cooling, and large single-crystal multi-alkali photocathodes grown on silicon carbide substrates. This paper presents recent progress on gun construction, commissioning plans, and preliminary major components test results.
Paper: WEP1352
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1352
About: Received: 13 May 2026 — Revised: 17 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP1353
Space Charge Effects on Spin Polarization in a High-Intensity Preinjector
2318
We are designing a high-charge, high-polarization preinjector for the EIC. Employing a Wien filter as the spin rotator immediately after the gun offers multiple advantages over the traditional dipole–solenoid spin rotator placed after the linac. However, this represents the first attempt to operate a Wien filter in a strong–space-charge environment. The energy spread and space-charge forces may influence spin dynamics. We analytical studied investigates space-charge effects on electron-beam polarization across the low-energy region, from the polarized electron gun to the linac entrance. We analyze spin degradation in the gun-to–Wien filter interface, within the Wien filter itself, and in the bunching section. A comprehensive evaluation of polarization-degradation mechanisms under space-charge conditions is presented. We further perform spin tracking through the full low-energy beamline using the space charging with spin tracking code General Particle Tracer (GPT) to validate the analytical model and incorporate higher-order effects.
Paper: WEP1353
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1353
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP1357
Injection Requirements for Electron Swap-Out in the EIC-ESR
2326
The Electron–Ion Collider (EIC) will be the first collider to use electron swap-out injection to maintain high bunch polarization during operation. Meeting the EIC performance goals places stringent requirements on the Electron Storage Ring (ESR) injection process: the injected bunch must be introduced with minimal disturbance to the hadron beam, and electron losses must remain negligible to avoid detector background. This work summarizes the key ESR injection requirements, including orbit accuracy, injected emittance, and fast kicker requirements needed to meet the overall EIC performance requirements.
Paper: WEP1357
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1357
About: Received: 01 Apr 2026 — Revised: 21 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP1375
NSLS-II Storage Ring Auxiliary Dipole Power Supply
2333
The National Synchrotron Light Source II (NSLS-II) storage ring requires a high-current (400 A), high-voltage (1 kV) dipole power supply system to maintain stable beam operations. Despite the high reliability of the primary system, a 2022 failure event resulted in over 20 hours of beam downtime, highlighting the necessity for enhanced operational resilience. This paper presents the design and implementation of an in-house designed auxiliary dipole power supply system developed to mitigate such risks. The auxiliary system utilizes a modular architecture with N+2 redundancy and high-frequency switched-mode power converters with active power factor correction. This design eliminates large 60 Hz transformers, reducing the system footprint to 10% of the original installation while enabling hot-swappable servicing. A transfer switch ensures a rapid transition from primary to backup systems in under 20 minutes. To maintain stringent orbit stability, the system incorporates a custom DC EMI filter and a series-pass linear amplifier, achieving a measured current stability of 1.71 ppm (DC to 10 kHz). These results demonstrate the system's effectiveness in reducing recovery time and enhancing the overall reliability of NSLS-II beam operations.
Paper: WEP1375
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1375
About: Received: 11 May 2026 — Revised: 20 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP1614
Development of STCF S-Band High-Gradient traveling wave accelerating structures
2361
The Super Tau-Charm Facility (STCF) is a next-generation electron-positron collider project proposed in China, designed to explore frontier physics in the tau-charm energy region. The facility's accelerator is required to provide electron and positron beams with tunable energies ranging from 1.0 to 3.5 GeV. This study presents the design of a traveling-wave accelerating structure for the STCF. By optimizing the regular-cell configuration, a high shunt impedance is achieved. The peak electric field in accelerating structure is reduced by adjusting the accelerating gradient profile, and an under-coupled output coupler design is adopted to enhance the performance of the accelerating structure. The objective is to achieve an accelerating gradient of 22.5 MV/m with an input power of 45.3 MW, and to further increase the power in pursuit of high-gradient operation in the S-band.
Paper: WEP1614
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1614
About: Received: 15 Apr 2026 — Revised: 27 Apr 2026 — Accepted: 15 May 2026 — Issue date: 22 May 2026
WEP1615
Beam Adjustment based on the Gradient Boosting Decision Tree Analysis in the KEK Electron/Positron Injector LINAC
2364
KEK-LINAC is an electron/positron linear accelerator used as the injector for the synchrotron radiation facilities (PF ring and PF-AR) and SuperKEKB. The stable operation of experiments at these facilities requires reliable beam supply from the LINAC. We have newly introduced an analytical method based on gradient boosting decision tree (GBDT) to further enhance our beam adjustment capability. GBDT is one of machine learning methods and has been used as an exceptionally effective model for tabular data. The GBDT analysis handling hundreds of LINAC operating parameters predicted accurately beam’s charge and position in the LINAC. Furthermore, by performing SHAP analysis, we have identified key parameters for the beam adjustment and correlations between the parameters. Furthermore, it was found that a model trained by the analyses can be utilized as a surrogate model for fast simulation of beam behavior in the LINAC. The results of beam adjustment with the GBDT analyses will be shown in this presentation.
Paper: WEP1615
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1615
About: Received: 12 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEP1621
Status of the Compton Polarimeter Project at BEPCII
2376
A laser Compton polarimeter is being developed at the Beijing Electron Positron Collider (BEPCII) for non-destructive diagnostics of transverse electron beam polarization. The project reuses a dismantled wiggler beamline and experimental hutch to transport a circularly polarized 532 nm pulsed laser beam to the electron ring and to guide the backscattered photons to a detector in the hutch. This paper summarizes the present project status, including beamline and optical system upgrades, detection of Compton backscattered photon signals, and recent commissioning with the TaichuPix-3 pixel detector.
Paper: WEP1621
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1621
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP2601
Higher Order Analysis for the Wakefields of a Single-plate Corrugated Structure
2392
Wakefields induced during the interaction of beam-environment could cause strong distortion of electron beam longitudinal and transverse phase space. Numerical modeling of the effect often relies on approximating the externally obtained point-charge wake with second-order Taylor expansion and convolving with beam distribution during particle tracking. In this contribution, we extend the method to the third order. We apply the method to the case of a transversely tilted beam traveling through a corrugated wakefield structure.
Paper: WEP2601
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP2601
About: Received: 15 Apr 2026 — Revised: 20 Apr 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP4606
Coherent Oscillation Simulations of Beam Instability Generated During Debunching for J-PARC Slow Extraction
2490
The J-PARC Main Ring (MR) has achieved a high extraction efficiency above 99.5% during 30 GeV slow extraction at the current beam power of 92 kW (8.1x10^13 ppp). However, at beam powers above 30 kW, we observed ring-wide beam loss due to transverse beam instability associated with vacuum pressure rise and electron cloud, believed to be triggered by longitudinal microwave structure in the beam. To achieve stable operation, we implemented phase offset injection into RF buckets and a two-step RF voltage reduction technique for debunching, in addition to chromaticity control. The generation of the longitudinal microwave structure and coherent transverse oscillation by the electron cloud during debunching has been investigated using a newly developed simulation code. The simulation predicts the generation of the longitudinal microwave structure under known ring coupling impedances. The code models the electron cloud–beam interaction as a transverse impedance derived from an assumed neutralization factor. The simulation results will be compared with measurements from a wall current monitor and a beam position monitor. Through this study, we will explore further instability mitigation strategies toward higher beam intensity operations planned for the future.
Paper: WEP4606
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4606
About: Received: 14 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
WEP4646
Conceptual design of a 2.45 GHz ECR ion source for proton therapy
2546
Proton therapy has attracted increasing attention because of its favorable dose distribution enabled by its Bragg-peak behavior. Motivated by the proton therapy facility project at Shanghai Synchrotron Radiation Facility (SSRF), a 2.45 GHz ECR ion source has been designed and fabricated. This paper presents the conceptual design of the prototype, together with simulation results of the magnetic field configuration, the ridged waveguide and the beam extraction.
Paper: WEP4646
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4646
About: Received: 12 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEP4654
Synchronization of longitudinal hollow electron beam and ion beam in a storage ring
2564
In the cooling storage ring, a low-temperature electron beam from the electron cooling device overlaps with a high-temperature ion beam in the storage ring. The overlap occurs at the same average velocity for a certain distance. Through Coulomb interaction, electrons absorb excess energy from ions. This reduces the transverse emittance and longitudinal momentum spread of the ion beam, and increases its phase space density. When cooling a Gaussian-distributed pulsed ion beam with a longitudinal hollow electron beam, the pulses must align at the longitudinal center. This article introduces a synchronization scheme for longitudinal hollow electron beams and ion beams. The scheme includes pulse measurement, triggering delay, synchronization monitoring, and future feedback for automatic correction. This ensures the pulses are always synchronized. The scheme will be used in longitudinal hollow electron beam cooling experiments and will support future investigations into the cooling process.
Paper: WEP4654
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4654
About: Received: 01 Apr 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
WEP5080
Computing coherent synchrotron radiation from Liénard-Wiechert potentials
2744
The linac-based test accelerator FLUTE contains a bunch compressor to create few-fs scale bunches that generate coherent radiation in the THz regime. The form and spectrum of the THz pulse strongly depend on the evolution of the bunch along the bunch compressor, and hence on the paths of the particles. From a given path of a charged particle, one can compute the emitted radiation by means of the Liénard-Wiechert potentials. A problem with this approach is that one needs to solve an implicit equation for the retarded time. Here, we instead compute the retarded time from the particle time and observer position. Furthermore, the Liénard-Wiechert potentials depend on the acceleration, while macro-particle tracking only yields the particle positions and momenta at fixed times. To compute the acceleration, we interpolate the data by twice differentiable functions. We compare the numerical results to the analytical benchmark case of synchrotron radiation. Finally, we compute the coherent radiation emitted of simulated bunches during compression.
Paper: WEP5080
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5080
About: Received: 16 Apr 2026 — Revised: 14 May 2026 — Issue date: 22 May 2026
WEP5090
Status of the PERLE’s injector
2770
The ERL accelerator called PERLE is under construction on the campus of Paris-Saclay university. PERLE is an Energy Recovery Linac which aims to reach 250 MeV 20 mA cw, namely 5 MW of beam power. First brick of this accelerator is the injector whom the main components are the DC photo-injector and a booster holding 4 superconducting cavities. This paper will give an overview of the injector’s design, technical details about major components and the schedule of the construction.
Paper: WEP5090
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5090
About: Received: 12 May 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
WEP5114
Characterization of longitudinal electron beam quality at the soft X-ray beamline of SwissFEL
2834
Longitudinal electron beam quality is key at X-ray free-electron lasers (FELs), where electron beams with small slice energy spread and a well-preserved current profile are required to ensure optimal, stable performance. Collective effects such as microbunching instability (MBI) and intrabeam scattering (IBS) can significantly degrade the longitudinal phase-space of the electron beam during multi-stage compression and are therefore a concern across FEL facilities. In this contribution, we will present systematic characterization studies of these mechanisms at the SwissFEL soft X-ray beamline Athos. We will show longitudinal phase-space measurements using radiofrequency transverse-deflecting structures for different accelerator and compression conditions. These characterization studies represent a first step towards the optimization of multi-stage compression schemes aimed at mitigating MBI and IBS effects.
Paper: WEP5114
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5114
About: Received: 08 May 2026 — Revised: 12 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP5118
Effect on 7 TeV proton beams from the residual multipolar fields in the HL-LHC Hollow Electron Lens
2846
Hollow electron lenses are a promising tool for controlling beam halo at high-intensity colliders like the HL-LHC. A perfect lens can efficiently deplete particles above the inner radius of the electron beam while leaving the core – which travels through a nominally zero-field region – unaffected. However, residual multipolar fields in the electron beam and non-ideal compensations of entry and exit regions of the electron beam can lead to emittance growth and other undesired effects on the circulating-beam core. This is a particular concern for the operation with pulsed electron beam currents that ensures the fasted depletion rates. In this study, updated two-dimensional field maps from recent studies at CERN's hollow electron beam test stand are used to quantify these effects under HL-LHC conditions. Beam-dynamics simulations are performed to evaluate the emittance evolution and identify the dominant field components contributing to core degradation. The analysis also considers compensation of the dipolar component using nearby electric kicker magnets.
Paper: WEP5118
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5118
About: Received: 06 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
WEP5120
Beam Dynamics Study for a Modified Low-Emittance RF Photogun
2854
High-brightness and low-emittance beams generated in RF-gun–based accelerators are essential for a number of applications, such as free-electron lasers (FELs), ultrafast electron Diffraction facilities and THz radiation sources. In these accelerators, the final beam characteristics are determined both, by the properties of the electron gun and by the influence of the electromagnetic system along the beamline. To meet the requirements imposed on beam characteristics, it is essential to identify the optimal parameters of the RF gun and the magnetic system. In this paper, beam dynamics studies of a modified RF photogun for the AREAL and REGAE accelerators are presented, with emphasis on transverse emittance compensation. Simulations were conducted by adjusting the parameters of the focusing and RF systems to identify the optimal configuration of the modified RF gun.
Paper: WEP5120
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5120
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
WEP5129
Benchmarking of the PENELOPE/PENH and PHITS codes for calculation of beam quality correction factors in therapeutic proton beams
2873
This work benchmarks the PENELOPE/PENH (2021 version) and PHITS Monte Carlo codes for calculating beam quality correction factors (kQ) in therapeutic proton beams. The latest PENH extension to PENELOPE enables proton transport simulation, including an approximate description of nuclear reactions and neutron production. PHITS, conversely, is an established multi-particle transport code covering protons, neutrons, and electron-gamma showers. The study compares simulated absorbed doses and kQ factors by modeling three configurations: a thin reference water cavity, a plane-parallel air cavity, and a cylindrical air cavity (representing typical ionization chambers). To determine the kQ factors, simulations involve a 1.25 MeV photon reference beam (Cobalt-60) and a 150 MeV monoenergetic proton beam. The computed results are validated against equivalent simulations published in the literature and obtained using FLUKA and GEANT4/TOPAS. This comparison assesses the suitability and consistency of the PENELOPE/PENH and PHITS codes for accurate clinical proton beam dosimetry.
Paper: WEP5129
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5129
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
WEP5130
Benchmarking the PENH Monte Carlo Code Against PHITS: Assessment of Proton Depth-Dose
2877
This study provides a benchmark of the PENELOPE/PENH (2021 version) Monte Carlo code for proton transport using reference results from the established PHITS code. The comparison focuses on absorbed-dose distributions generated by a finite-spot proton pencil beam. Integrated depth-dose curves were simulated for monoenergetic beams ranging from $100 \text{ to } 250 \text{ MeV}$ incident on a water phantom. The degree of agreement between PENH and PHITS is quantitatively assessed for depth-dose behavior. The results evaluate PENH’s accuracy and establish its suitability for general proton transport applications.
Paper: WEP5130
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5130
About: Received: 13 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
WEP5140
The 3D-PIC simulation of the beam-plasma interaction inside of Gabor Lenses
2897
Experimental results of the beam transport through a Gabor lens system were not fully understood in the past. The measurement campaign presented at IPAC2013 will be considered as an example with an alternative explanation. Simulation results done by the TraceWin code will be presented and beam impact on the electron column discussed. Especially production of secondary electrons by an ion impact can have massive influence on plasma state and creating waves and instabilities. Additionally, a large scale multi-particles 3D Monte-Carlo-PIC (particle-in-cell) simulations with electrons and ions were carried out. Goal was to understand collective phenomena in non-neutral plasma generated by passing beam in various scenarios. Up to $10^7$ macroparticles were implemented in parallel processing on 50 processors of the FUCHS Cluster. Possible influence on the focusing properties and imaging quality will be evaluated and the dependence on time scale and ion beam energy discussed. Simulation results will be presented with an impact on future designs.
Paper: WEP5140
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5140
About: Received: 13 May 2026 — Revised: 16 May 2026 — Issue date: 22 May 2026
WEP5144
Ion Trapping Studies and Mitigation Strategies for the EIC ERL-Based Strong Hadron Cooler
2901
An Energy Recovery Linac based strong hadron cooler was previously considered for the Electron-Ion Collider. The required electron beam parameters for variable-energy strong hadron cooling place significant constraints on ion trapping and collective effects. This paper presents initial studies of these constraints through a combination of analytical modelling and numerical simulations of ion production, trapping behaviour, and mitigation strategies. A multi-bunch tracking framework based on ELEGANT with the ionEffects module is used to simulate machine operation over millisecond time scales, corresponding to more than 3 × 10^5 electron bunches. The simulations include modelling of ionisation processes together with transverse electron–ion dynamics, allowing the evolution and accumulation of ions to be investigated. Analytical expressions based on Gaussian beam distributions are used to estimate ion trapping conditions and benchmark the simulation results. A bi-periodic bunch spacing scheme is also investigated as a possible mitigation method by detuning the ion oscillation frequency. These studies provide an initial assessment of ion trapping in the strong hadron cooler and demonstrate possible approaches for reducing beam–ion effects.
Paper: WEP5144
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5144
About: Received: 13 May 2026 — Revised: 17 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP6006
Gradient-based laser control for end-to-end photoinjector emittance optimization at EuXFEL
2937
Achieving low emittance at the photoinjector is essential for meeting the performance targets of the European XFEL, particularly for high photon energies and future high-duty-cycle operation. Both the temporal structure of the drive-laser pulse and the RF-gun settings contribute significantly to the final beam quality, yet their optimization is complicated by strong nonlinearities in the laser system and complex gun response. We have developed a differentiable, physics-based model of NEPAL, the photoinjector laser of EuXFEL, that enables gradient-driven optimization of the temporal UV pulse shape. The model captures the relevant nonlinearities of the optical chain and allows direct optimization of spectral amplitude and phase to obtain target UV profiles at the photocathode. In parallel, a machine-learning surrogate model is being implemented to optimize the RF-gun operating parameters. Together, these tools provide an end-to-end control framework for emittance reduction at EuXFEL. Initial results demonstrate that the differentiable model enables accurate temporal UV pulse shaping at EuXFEL. Work is ongoing to integrate this approach with ML-assisted gun optimization within the proposed end-to-end control framework.
Paper: WEP6006
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6006
About: Received: 18 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
WEP6012
Photoinjector Emittance Optimization using Latent Laser Pulse Representations
2949
We present a beam dynamics study aimed at optimizing the transverse emittance of electron bunches in a photoinjector, motivated by the performance requirements of Free-Electron Lasers. The study is conducted using the accelerator configuration of the Photo Injector Test Facility at DESY in Zeuthen (PITZ), with the overarching goal of developing emittance optimization strategies for the European XFEL photoinjector. To this end, we perform large-scale beam dynamics simulations using the simulation code ASTRA, systematically sampling from a low-dimensional latent representation of temporal laser pulse profiles. This latent space is learned from a broad set of physically plausible pulses using a Wasserstein Autoencoder (WAE), enabling compact and structured exploration of pulse shape variations. The ability to efficiently sample from this representation supports targeted emittance studies that would be computationally prohibitive in the original high-dimensional shaping parameter space. For each simulation, beam quality metrics such as normalized projected emittance and slice mismatches are recorded. The study reveals meaningful correlations between latent coordinates and beam quality, demonstrating the utility of WAE-based representations in guiding laser pulse design. We briefly outline future directions involving neural surrogate models to accelerate beam emittance optimization.
Paper: WEP6012
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6012
About: Received: 15 Apr 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
WEP6014
FEL Power Profile Predictions with Image-Based Machine Learning at FLASH
2953
Accelerator operators and beamline users can highly benefit from accurate and efficient measurements of FEL (free-electron laser) pulse power profiles. The use of machine learning to predict such profiles is an area of rapid development in the field. This work presents recent measurements and tests at the FLASH FEL at DESY of an image-based machine learning application developed to facilitate online FEL power profile reconstruction. The reconstruction has been performed using machine learning predictions of the longitudinal phase-space (LPS) of electron beams unaffected by the FEL process, originally measured using a transverse deflecting structure. The predictions were used in combination with longitudinal measurements of the LPS of the electron beam after lasing, which does not interfere with delivery to users, to reconstruct the FEL pulse. The results of the reconstruction process have been validated by comparison with a reference method which does not rely on machine learning.
Paper: WEP6014
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6014
About: Received: 13 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
WEP6018
High-Dimensional Bayesian Optimization for Sparse Objectives: an Application for Automated Beam Commissioning in the Low Energy Ion Ring at CERN
2969
Recent advances in high-dimensional Bayesian Optimization have opened the door to new tools for beam commissioning. At the CERN Low Energy Ion Ring (LEIR), several tuning challenges arise from the complex parameter space governing beam transfer and accumulation dynamics. In this paper we benchmark several state-of-the-art High Dimensional Bayesian Optimization methods to optimize the transfer from Linac3 to LEIR and maximize the accumulated beam inside the ring. We evaluate algorithms based on different strategies: trust region approaches (TuRBO), sparse axis-aligned subspace priors (SAASBO), nested embeddings for mixed spaces (Bounce), and length-scale-adapted priors in regular Bayesian Optimization. Our results demonstrate the relative strengths of each method in the context of particle accelerator optimization, where sample efficiency is critical, the objective function exhibits sparsity in relevant dimensions, and the parameter space contains both local and global structures. The benchmarking provides practical insights for selecting appropriate algorithms for beam commissioning tasks, considering factors such as convergence speed, computational overhead, and robustness to noisy observations.
Paper: WEP6018
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6018
About: Received: 13 May 2026 — Revised: 17 May 2026 — Issue date: 22 May 2026
WEP6021
Online Reinforcement Learning for Stripper Foil Aging Compensation at the CERN Low Energy Ion Ring
2973
Stripper foil degradation at the CERN Low Energy Ion Ring (LEIR) poses a significant challenge for beam operations. As the heavy ion beam passes through the stripper foil at the end of the injecting linac, the foil degrades over time, altering the beam energy distribution and reducing the achievable accumulated intensity in the ring. Addressing this operational limitation using traditional control approaches is challenging due to the complex, multi-dimensional nature of the multi-turn injection process. This paper presents a reinforcement learning-based controller to compensate for foil degradation and maintain ring performance. The controller observes longitudinal Schottky spectra encodings and time-of-flight measurements from the linac to adjust the ramping and debunching cavity phases, and electron cooler gun and orbit bump in real-time. We demonstrate that pre-training the agent in a data-driven surrogate model significantly improves both controller performance and sample efficiency during deployment.
Paper: WEP6021
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6021
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
WEP6030
Rate capabilities of radiation monitors based on diamond detectors
2992
Diamond detectors are widely used in harsh radiation environments due to their intrinsic radiation hardness. At high particle fluxes, single-particle measurements in counting mode are challenging because of pile-up, requiring a transition to current measurement. In this study, a 500 MBq $^{90}$Sr beta source was used to investigate the limitations of the counting mode and the transition to current mode with diamond detectors. A dedicated readout was implemented using a CIVIDEC ROSY$^®$ data acquisition system, with a simultaneous counting and current mode. Low-noise CIVIDEC charge-sensitive spectroscopic amplifiers with FWHM of 10 ns, 30 ns, 50 ns, 100 ns, and 180 ns were compared. The correlation between the measured count rates and the current was studied.
Paper: WEP6030
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6030
About: Received: 09 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
WEP6031
Experimental Evaluation of a Digitizer Designed for ACCT Beam Current Transformers
2995
To integrate the signals of beam current transformers into accelerator control systems, particle accelerators require high-performance digitizers with optimized bandwidth, sampling rate, and dynamic range. They must be accurate and reliable. And they should be easy to deploy and operate. A specialized digitizer was developed to interface the Bergoz Instrumentation ACCT sensor and its analog front-end electronics to an accelerator control system. It allows waveform acquisition preserving the quality of the analog signal and controls the ACCT configuration. Communication is implemented over Ethernet through a simple command protocol, and an EPICS soft IOC is provided. The digitizer was tested with two ACCTs installed at the CHUV Oriatron Linac and a third at the METAS electron beamline. Results demonstrate improved signal-to-noise ratio, adaptability to multiple beam types, and simplified deployment compared to general-purpose digitizers.
Paper: WEP6031
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6031
About: Received: 11 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEP6036
Beam positions monitors for PERLE injector
3006
PERLE is an Energy-Recovery Linac (ERL) to be constructed at IJCLab in Orsay. It will be the First ever multi-turn ERL with superconducting RF (SRF) acceleration, and the first ERL with the ambition to reach 5MW beam operation. Diagnostics are a key element for PERLE operation and among diagnostics, Beam position monitors (BPMs) cover a wide range of applications. We report BPM goals for a proper operation of PERLE, it also details the design of BPM detectors and eludes the steps for their realization. it finally discusses the design of BPM electronics to match the presence of multiple beams which need to be individually diagnosed and controlled.
Paper: WEP6036
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6036
About: Received: 06 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEP6041
Current Profile Reconstruction by Passive Streaking of Low Charge, Low Energy Electron Bunches in Dielectric Loaded Waveguides
3021
Advanced accelerating techniques are evolving rapidly, enabling high energetic electron beams with significantly decreasing footprint. While the accelerating structures shrink impressively, longitudinal diagnostic components with femtosecond resolution like transverse deflecting structures still demand a significant amount of space and complex infrastructure, are costly and require precise synchronization of their power source with the arriving electron bunch. The TWAC project¹ aims for a fully-integrated compact accelerator, delivering ultrashort bunches (≈10s of fs) at low charge and energy (10 pC, 10 MeV), requiring corresponding small footprint, cost-efficient longitudinal diagnostics. Here, the retained method is passive streaking in dielectric loaded waveguides² in which the self-excited transverse wakefields are imposing a varying kick dependent on the intra-bunch longitudinal position. The new parameter regime is investigated at the ARES linac, firstly at medium energy (≈60 MeV). A novel forward propagation reconstruction algorithm has been developed, based on a waveguide mode expansion with more than 100 modes to properly model the excited wake.
Paper: WEP6041
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6041
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
WEP6049
First Measurements of the Transient Electrical Near-Field of Electron Bunches in the FLUTE In-Air Section
3036
The Ferninfrarot Linac- und Test-Experiment (FLUTE) at the Karlsruhe Institute of Technology (KIT) is a compact linac test facility providing sub-picosecond to femtosecond short electron bunches with energies up to several tens of MeV. The transient electric near-field of such bunches is relevant for understanding coherent THz emission and for developing compact field-sensitive beam diagnostics. Here, we present first electro-optical measurements of bunch-induced near-field signals in the FLUTE in-air section using a photonic-integrated Mach-Zehnder-interferometer sensor placed close to the beam axis. The measured delay-dependent response shows features consistent with electro-optical detection of the transient electric near field of the bunch. Our results establish a basis for future spatially resolved measurements with varying accelerator parameters.
Paper: WEP6049
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6049
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
WEP6052
Using a Timepix3 Pixel Detector for a Compton Backscattering Polarimeter
3043
The Electron Stretcher Facility (ELSA) in Bonn has the capability to accelerate spin-polarized electrons. To know the degree of polarization an in situ measurement is necessary. A Compton backscattering polarimeter located in the stretcher ring allows for in situ measurements of the beam polarization degree. Here a high power cw-laser beam is scattering with the electron beam. The backscattered photons reach energies of up to several 100 MeV and polarisation dependent shift in the vertical profile can be observed from these photons. Currently an in-house custom-built silicon strip sensor is used. To obtain a better understanding of the measured profile, 2D information is crucial. Here the Timepix3 ASIC (55 µm pixel pitch) with a 500 µm thick silicon sensor is a suitable candidate, allowing for 2D information with an excellent time resolution (25 ns), enabling for parallel time resolved horizontal and vertical profile measurements. Using an in-house developed readout allows for high flexibility and adaptability. The detector concept as well as first measurements under various conditions of the vertical and horizontal profiles from polarized beams are presented.
Paper: WEP6052
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6052
About: Received: 13 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
WEP6053
Enhancing Beam Time Availability by a Factor of Two: Simultaneous Operation of Hadron Physics and Detector Test Beam Lines at ELSA
3046
The electron accelerator facility ELSA houses two external high-energy beam lines. These deliver primary electron beams with energies between 0.8 and 3.2 GeV, extracted via slow resonant extraction from a synchrotron to a total of three different experimental sites. One beam line hosts two hadron physics experiments, while the second, located on the opposite side of the synchrotron, is used for detector tests and medical physics experiments. Recently a new operation mode has been developed to serve both external beam lines with an extracted electron beam simultaneously. This enables running detector test experiments at low rates (tens of kHz) alongside high-rate hadron-physics experiments at GHz extraction rates, significantly increasing beam time availability. We present properties and underlying beam dynamics of this operation mode, with particular emphasis on advanced methods for rate control at the second beam line.
Paper: WEP6053
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6053
About: Received: 12 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
WEP6068
Capabilities and Limitations of Non-Redundant Aperture Interferometry for Beam Size Measurements
3065
Non-Redundant Aperture Interferometry (NRAI) is a beam characterization technique developed at ALBA in collaboration with radio-astronomy institutes. It enables the single-acquisition measurement of the full 2D transverse profile of the electron beam using visible synchrotron radiation. To better understand the technique limitations and performance, we performed extensive SRW simulations and compare them with experimental data. This paper presents the results of these studies, which define the capabilities and limits of NRAI applied to the current ALBA machine, as well as its feasibility for the ALBA II upgrade.
Paper: WEP6068
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6068
About: Received: 13 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
WEP6074
IFMIF-DONES Beam on Target Diagnostics based on Optical Methods: OTR and Fluorescence
3076
The IFMIF-DONES facility located at Escúzar in Spain will consist of an accelerator delivering 125 mA of 40 MeV deuterons onto a liquid lithium target. The beam profile at the target will have a rectangular footprint with two side peaks to satisfy the irradiation requirements. The environment conditions are characterized by a high radiation background and the presence of lithium vapor. Additionally, deuteron scattering with residual gas and secondary-electron production occur. To measure the footprint under these conditions optical methods are designed based either on measuring Optical Transition Radiation (OTR) of the beam passing through the liquid lithium or on the Beam Induced Fluorescence (BIF) of the residual gas in the proximity of the liquid lithium. Both alternatives have its advantages and drawbacks. In this paper it is described the pros and cons of both alternatives. Furthermore, an experiment to better characterise the OTR response in liquid lithium is also presented.
Paper: WEP6074
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6074
About: Received: 11 May 2026 — Revised: 18 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
WEP6078
Beam instrumentation for AWAKE from Run 2b to Run 2c
3092
The AWAKE experiment at CERN is a proof-of-principle facility that uses proton-driven plasma wakefields to accelerate externally injected electrons. Since initial operations in 2016, multiple experimental phases have been completed, with the most recent being Run 2b. Beam diagnostics played a crucial role during this phase, enabling reliable operation and characterisation of the particle beams. The next phase, Run 2c, planned to begin in 2029, will introduce a second electron beamline delivering 150 MeV, 200 fs (RMS)-long electron bunches together with a second plasma. The increased experimental scale and the new measurement requirements impose new demands on beam instrumentation, requiring upgrades to existing systems and the development of new, specialised diagnostics. This contribution presents a non-exhaustive overview of the diagnostic systems used during Run 2b, describes the planned upgrades and developments for Run 2c, and discusses the associated integration challenges.
Paper: WEP6078
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6078
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
WEP6079
A new analogue acquisition for the BPM of CERN PS
3096
The bunch-by-bunch and turn-by-turn beam trajectory measurement system of the CERN PS accelerator has been in operation for several years. To ensure long-term reliability, the consolidation of the analogue acquisition chain is foreseen during the upcoming LS3 long shutdown including a new architecture with improved performance, which is currently under test in the PS accelerator for final validation. The key element is a custom-designed high impedance head amplifier, replacing the 50Ω amplifier used by the current system, with the advantage of improving, at the same time, bandwidth, dynamic range and noise level. Increased dynamic range opens the possibility of measuring longer acceleration periods without gain switching and better resolution. Increased bandwidth allows the measurement of more beam configuration, in particular with shorter bunch to bunch distance. However, improved performances come at the expense of placing active electronics close to the beamline, in locations with significant radiation exposure, therefore requiring radiation-tolerant electronics. An overview of the PS trajectory system is presented, with the focus on the design of the new analogue acquisition, along with the preliminary bench and beam measurement results.
Paper: WEP6079
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6079
About: Received: 08 May 2026 — Revised: 20 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEP6089
Feasibility of Non-invasive OSR Diagnostics in the AWAKE run-2C Injection Region
3120
AWAKE is CERN's proton-driven plasma wakefield acceleration experiment, currently advancing toward Run-2c to demonstrate the higher energy acceleration of electrons while maintaining the beam quality. A second electron beam (of 150 MeV energy), produced in a newly installed electron source, will be injected and accelerated to several GeVs while aiming to keep good emittance. Diagnostics are being upgraded for this geometrically constrained injection-region to enable single-shot characterization of that beam, among which this contribution evaluates the feasibility of optical synchrotron radiation (OSR) as a non-invasive real-time mean. OSR can provide shot-by-shot transverse position and profile information without disrupting beam delivery, critical for benchmarking beam-alignment and quality check. The prompt, non-invasive nature also makes it a candidate for future virtual diagnostic implementations, where online beam profiles could inform predictive models or feedback correction schemes. For performance optimizations the expected OSR photon flux, photon statistics, projected image quality are computed with realistic imaging optics and detector quantum efficiency. Results demonstrate that sufficient OSR signal can be extracted through this compact optical chain to achieve meaningful single-shot transverse profile measurements.
Paper: WEP6089
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6089
About: Received: 11 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
WEP6092
Transverse Phase Space Tomography at CLARA Using Generative Machine Learning
3132
CLARA is a high-brightness electron beam facility at STFC Daresbury Laboratory, aiming to deliver ultra-short electron bunches to a wide range of user experiments. CLARA has recently resumed operations after a major upgrade, and is currently undergoing beam commissioning at its nominal energy (250 MeV) and bunch charge (250 pC). During commissioning, studies of the transverse beam dynamics will be vital for optimizing the accelerator’s performance, and for validating the simulation models used during its design. Phase space tomography is a powerful technique for reconstructing a beam’s charge distribution in phase space; recent machine learning advances have led to faster, higher-resolution tomographic methods such as generative phase space reconstruction. In this contribution, we present detailed measurements of the 4D transverse phase space at CLARA. We validate the reconstructed phase spaces by using them to accurately predict the appearance of the electron beam for different beam optics configurations. Our results demonstrate methods that are now used for routine characterization of the CLARA beam, and represent the first emittance measurements at the accelerator’s design energy.
Paper: WEP6092
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6092
About: Received: 12 May 2026 — Revised: 17 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
WEP6109
Test Bench Design and First Measurement Results for the PETRA IV FOFB Actuator Chain
3177
A fast orbit feedback system is currently being developed for the upcoming PETRA IV at DESY Hamburg. The performance of the FOFB system depends mainly on the frequency response of the subsystems, i.e. the corrector magnets, power supplies, cables and vacuum chambers. A test bench is being developed for measuring the field quality of FOFB corrector magnets and system identification of all integrated subsystems in the kHz range. The first design of the test bench and the initial idea for the different types of measurement methodologies to find the frequency response and magnetic field of corrector magnets are presented below. The subsystems integration and combined frequency response of the FOFB system will be measured in later stage of the project.
Paper: WEP6109
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6109
About: Received: 11 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
WEP6121
High-Precision Three-Axis Teslameter for Superconducting Magnet Alignment of a Gyrotron at the Swiss Plasma Center
3207
This paper presents the design of a high-precision three-axis Teslameter and its application for magnetic field alignment of a superconducting magnet prior to gyrotron installation, at the Swiss Plasma Center. The instrument integrates an advanced 3-axis Hall sensor with an ultra-compact sensitive volume of 0.10×0.01×0.10 mm³, enabling true point-like vector field measurements. We describe the sensor architecture, Teslameter performance, and calibration procedures, including precise orthogonality characterization. The Teslameter achieves DC accuracy better than 100 ppm and 1 µT resolution. The system was employed to verify and optimize magnetic field alignment for high-power gyrotrons, vacuum electronic devices generating sub-terahertz radiation via the cyclotron maser instability. Efficient operation of these devices requires that the magnetic field axis remain confined within a cylinder of 0.15 mm diameter over a 700 mm length to maintain correct electron–field interaction. Using the Teslameter, the magnetic field was mapped with high accuracy, enabling fine realignment of the superconducting magnet and ensuring the electron beam coincides with the electric field maximum of the transverse electric (TE) mode. This methodology guarantees optimal gyrotron performance, contributing to reliable and efficient operation of Electron Cyclotron Resonance Heating and Current Drive systems in magnetic confinement fusion research.
Paper: WEP6121
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6121
About: Received: 28 Apr 2026 — Revised: 12 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
WEP6124
Radiation Protection for Laser–Plasma Accelerator Facilities at DESY
3219
DESY draws on more than six decades of experience in the development, operation, and radiation protection of large-scale user facilities such as PETRA III, FLASH, and the European XFEL. In parallel, the investigation of novel accelerator technologies for future applications has become a key focus. Laser-plasma acceleration (LPA) offers the potential for highly compact, high-gradient sources, as demonstrated by the LUX, KALDERA, and FORWARD facilities at DESY. However, LPA systems introduce new challenges for radiation protection due to broadband emission spectra and the interplay of high-power lasers with plasma-generated secondary radiation fields. This contribution presents the radiation-protection concept for LPA facilities at DESY, covering shielding simulations and designs with a focus on the differences com-pared to conventional electron accelerators. Finally, operational experience from commissioning the KALDERA LPA and further development stages is discussed, illustrating practical implementation.
Paper: WEP6124
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6124
About: Received: 12 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
WEP6138
A Beam Abort System for the Diamond-II Storage Ring
3240
Due to the high energy density of the Diamond-II low-emittance electron beam, the risk of damage to storage ring components is considered high. A dedicated beam abort system is one way to safely dump the beam and protect the machine from damage. In this paper, we present the design of a beam abort system for the Diamond-II storage ring. The requirements of the key components will be described, including the kickers, beam dump and controller. Simulations of the effects of beam loss on the beam dump surface and collimator blades will be shown.
Paper: WEP6138
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6138
About: Received: 11 May 2026 — Revised: 18 May 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
WEP6144
Modification of the transverse electron bunch profile with spatial light modulator at FLUTE
3247
The linac-based test facility FLUTE (Ferninfrarot Linac- Und Test-Experiment) at the Karlsruhe Institute of Technology (KIT) was designed as a test bench for accelerator technologies with a broad range of beam parameters. The electron bunches are generated in a UV photo-injector which offers laser pulse shaping as control of the beam parameters. The imprint of a transverse laser profile modulated by an spatial light modulator (SLM) onto the electron bunch was demonstrated at the low energy section of FLUTE. The addition of the linear acceleration structure and bunch compressor section, as well as the upgrade of the RF system, enables experiments with short-pulse electron bunches up to 90 MeV. For this contribution, the SLM was used to recreate the modified electron bunch profile and we present the observed characteristics after passing the traveling-wave RF structure and magnetic chicane.
Paper: WEP6144
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6144
About: Received: 12 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
WEP6150
Digital low level RF system for Elettra 2.0
3266
The new digital electronics of the four Radio Frequency (RF) plants for Elettra 2.0 (E2.0) is fully designed in house, both hardware and firmware. The Digital Low-Level Radio Frequency (DLLRF) works on a non-IQ sampling technique and it is benefiting from the huge internal development of a System On Chip (SoC) Field Programmable Gate Array (FPGA) boards realized for the electron beam position monitor electronics. Each RF plant will have its own machine protection system based on FPGA board to minimize the interlock intervention time. Initial tests of these new electronics have been carried out during last run of Elettra, however the complete commission is carried out using the RF power plant available in the laboratory. This paper presents the design choices and the performed tests that confirm the achievements of the system’s specification.
Paper: WEP6150
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6150
About: Received: 05 May 2026 — Revised: 19 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
WEP6156
Surrogate models for the European XFEL operation
3277
Numerical beam dynamics simulation codes are essential for designing and studying particle accelerators, but their computational cost can make them unsuitable for online use and predictions during operations. The use of machine learning-based surrogate models can significantly reduce the required computational time whilst still providing an accurate prediction of the beam properties. In this paper, we present the first results on the training of surrogate models for the prediction of the longitudinal phase space (LPS) at the European XFEL. Finally, we discuss the potential application of such models in the development of a virtual diagnostic tool for use in the European XFEL control room as well as a fast estimator for the final LPS based on the user-provided compression parameters.
Paper: WEP6156
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6156
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
WEP6157
Global start-to-end optimization with Bayesian Optimization
3281
Controlling the beam longitudinal phase space (LPS) distribution is crucial for advanced free-electron laser operation modes. At the European XFEL, this task is particularly challenging due to the complex compression scheme, which includes three bunch compressors. We present an approach based on Bayesian optimisation that simplifies the search for compression configurations yielding current profiles with desirable features, such as a flat top or a pronounced spike at either the head or the tail of the bunch. Moreover, this method can also be applied to tune the RF parameters in start-to-end simulations to achieve better agreement with measured longitudinal phase space profiles.
Paper: WEP6157
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6157
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
WEP6172
Dilution Monitoring for the BDF-SHiP Target
3308
The BDF/SHiP experiment requires precise monitoring of the beam dilution pattern on the high-power target absorbing up to 350kW (avg.). This paper presents the conceptual design of a dedicated Beam Dilution Monitor (BDM), which will enable observation of the circular beam sweep pattern during 400GeV/c proton operation. The proposed system is based on Secondary-Emission Monitor (SEM) grids comprising 12μm-thick titanium bands. Detailed simulations were performed to evaluate signal formation, thermal response, secondary-electron collection, and the detectability of dilution magnet failure scenarios. Different detector geometries and interlock strategies were also investigated, demonstrating that the proposed BDM concept can provide sufficiently fast and reliable detection of dilution failures.
Paper: WEP6172
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6172
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
WEV1301
Accelerator Design Educational Primer – Conceptualizing and Optimizing the Hybrid LHeC-like Electron-Ion Collider Design
3351
The Electron-Ion Collider (EIC) Mission Need requires √s = 20–100 GeV (upgradable to 140 GeV) and luminosity 10³³–10³⁴ cm⁻² s⁻¹. The current ring-ring baseline achieves the full scope, including ~10³⁴ cm⁻² s⁻¹ across all energies. However, when the design is re-optimized for the lower boundary — accepting ~10³³ cm⁻² s⁻¹ and prioritizing cost — an alternative configuration emerges as more advantageous: a hybrid LHeC-like electron accelerator using multi-pass energy recovery linacs (ERL). This solution reduces electron-beam power by roughly an order of magnitude, yielding nearly a factor of two reduction in total project cost compared with the present baseline while still satisfying the minimum physics requirements. The study performs parametric cost and performance modeling, augmented by AI-driven optimization, to explore this design space. Serving primarily as an educational exercise for the next generation of accelerator physicists and engineers, the paper demonstrates modern design methods: rapid parametric scans, cost-driven optimization, and integration of AI tools. It examines technical feasibility, identifies critical R&D (high-current ERL operation, beam–beam effects, synchronization, etc.), and discusses how such re-optimization studies can be used to train designers in an era when artificial intelligence dramatically expands exploration of complex accelerator parameter spaces.
Paper: WEV1301
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEV1301
About: Received: 12 May 2026 — Revised: 19 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
WEV4301
Commissioning of the IOTA proton injector
3357
The Proton Injector for the IOTA storage ring (IPI) has been successfully constructed and commissioned at the Fermilab Accelerator Science and Technology (FAST) facility. It has demonstrated the capability to produce proton pulses of up to 14 mA at 2.5 MeV. Operating alongside with the existing electron injector, IPI enables expanded beam physics research and supports the development of novel accelerator technologies at the IOTA ring. This report presents the results of IPI’s construction and commissioning, as well as an overview of the experimental program using intense proton beams at IOTA.
Paper: WEV4301
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEV4301
About: Received: 18 May 2026 — Revised: 21 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
THO2M02
Results of the first interferometric measurements of undulator radiation from single electrons
3391
The aims of the CLARA experiment at the Fermilab Integrable Optics Test Accelerator (IOTA) were to directly measure the coherence length of undulator radiation emitted by a single electron and to test whether the radiation is in a pure classical Glauber coherent state or in a quantum mixture of coherent and Fock states. We used a Mach-Zehnder interferometer (MZI) to study visible radiation generated by 150-MeV electrons circulating in the ring. The relative delay between the two arms of the MZI was adjusted by varying the length of one of them with a resolution of 10 nm. The intensity of the circulating beam spanned several orders of magnitude, down to single electrons. A pair of single-photon avalanche diodes (SPADs) was placed at the output of the MZI arms to detect photocounts with high efficiency and timing resolution. We describe the observed interference patterns and photocount rates as a function of interferometer delay. The arrival time distributions of photocounts of undulator radiation, lasers and chaotic light are compared. The implications for the quantum-optical nature of the radiation are discussed. To our knowledge, these are the first direct measurements of this kind.
Paper: THO2M02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THO2M02
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
THO3T02
Terahertz techniques in the advanced accelerator landscape
3397
Terahertz (THz)-frequency particle acceleration provides a natural “bridge” between conventional electronic-based (radio-frequency RF) and novel photonic-based (laser plasma wakefields LWFA) drivers, offering stable, high-frequency, high-gradient fields for compact interactions, coupled with direct femtosecond-scale synchronization to the THz drive laser*. These unique properties ideally position THz technologies to enhance the capabilities of existing RF infrastructure, while also solving key challenges to help drive the transition towards compact high-gradient laser-based accelerator applications. As a key example, I will present our latest experimental results and simulations demonstrating efficient THz-driven chirping and energy modulation of relativistic electron bunches, enabling the compression of ultrashort bunches and picosecond-spaced bunch trains with femtosecond-scale "temporal-locking" to the THz drive laser**. These results unlock a potential array of advanced electron-laser applications requiring precise synchronization at the shortest timescales, such as pump-probe experiments with FEL light, single-shot ultrafast electron diffraction, electron-laser collisions to probe strong-field quantum electrodynamics and for high-quality LWFA through controlled external injection. On the latter I will discuss our work towards achieving this goal, in addition to highlighting the other unique roles THz technologies can play in the future advanced accelerator landscape.
Paper: THO3T02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THO3T02
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
THP2006
Realisation of the 1.5 GHz single-mode-cavity for PETRA IV
3430
A third harmonic system is planned for PETRA IV. One possible option for the third harmonic cavity is a novel single-mode cavity based on the choke-mode principle. The DESY device developed on this basis offers the following advantages over alternative designs: a) Very strong suppression of all unwanted modes. b) Coupling factor adjustable during operation. c) The wall currents induced by the fundamental mode are not disturbed by weld seams. This has a favourable effect on the shunt impedance and quality factor. d) The simple geometry of the cavity results in the smallest possible number of independent cooling circuits. The presentation describes the development work, introduces the design and highlights some of the cavity's outstanding features. It a also discusses the current construction of the cavity.
Paper: THP2006
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2006
About: Received: 24 Apr 2026 — Revised: 19 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
THP2023
The cool copper operation linac demonstrator project
3471
The ESRF long term strategy for the injectors upgrade includes the possibility of a full energy 6GeV linac. This linac is supposed to fit on the ESRF site leading to a maximum footprint of ~130m. High gradient accelerating structure technology from SLAC* was selected as the enabling technology to realize such a compact injector linac. The use of a phogun and pulse compression would imply small 6D beam phase space at extraction and a sensible cost reduction. The paper will introduce the Cool copper Operation Linac Demonstrator (COLD) project that has started at ESRF with the objective to realize a pre-injector linac and test all the enabling technologies for an high gradient cost effective 6GeV linac.
Paper: THP2023
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2023
About: Received: 28 Apr 2026 — Revised: 30 Apr 2026 — Accepted: 15 May 2026 — Issue date: 22 May 2026
THP2036
Echo-enabled harmonic generation at electron storage rings
3503
Echo-enabled harmonic generation (EEHG) has been proposed as a seeding method for free-electron lasers but can also be employed to generate ultrashort radiation pulses at electron storage rings. With the interaction of electrons with femtosecond laser pulses in two undulators (”modulators”), each followed by a magnetic chicane, a longitudinal phase space structure with high harmonic content is produced, which gives rise to coherent emission of radiation at harmonics of the laser wavelength. The duration of the coherently emitted pulses in a third undulator (”radiator”) is given by the laser pulse durations. Thus, EEHG pulses can be three orders of magnitude shorter but still more intense than conventional synchrotron light pulses. After reviewing proposals of EEHG at different storage rings, the latest results of a first demonstration experiment at the 1.5-GeV synchrotron light source DELTA at TU Dortmund University are presented.
Paper: THP2036
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2036
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP2037
Space-charge-enhanced energy modulation at FERMI
3507
High-gain harmonic generation (HGHG) is a seeding scheme for free-electron lasers (FELs), which improves the longitudinal coherence of the radiation output and reduces fluctuations of pulse energy, arrival time, and central wavelength compared to self-amplified spontaneous emission. In the HGHG scheme, laser-induced energy modulation is followed by a dispersive section, where part of the electrons form density maxima (“microbunches”) with the periodicity of the laser wavelength. The electrons between the microbunches have an energy spread correlated with the longitudinal coordinate. Longitudinal space charge (LSC) in a drift section tends to dilute the microbunches, while the correlated energy spread is reduced and even changes sign, if the drift section is long enough. In this case, a second dispersive section can be used to form new density maxima from the electrons between the initial microbunches, and the resulting energy modulation amplitude may be significantly larger than the initial one. Results from an experimental demonstration of this novel LSC-enhanced modulation scheme at FERMI, a seeded FEL user facility in Trieste, Italy, are presented.
Paper: THP2037
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2037
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2038
Undulator radiation from a single electron in a storage ring
3511
A low-intensity double-slit experiment in the time domain has been undertaken by measuring the spectral distribution of synchrotron light from a single relativistic electron in a storage ring. In two consecutive undulators with a dispersive section between them (known as optical klystron), an electron beam emits two temporally separated light pulses leading to a spectrum with interference fringes - in close analogy to the angular distribution of light behind two spatially separated slits. Experiments at the electron storage rings DELTA in Dortmund, Germany, and UVSOR-III in Okazaki, Japan, show directly that the spectral distribution of accumulated synchrotron light from a single electron is essentially the same as the spectrum from a beam of many electrons. While the latter is usually explained by interference between simultaneous the light waves from the two undulators, the single-electron experiments demonstrate the uncertainty of the photon source point over several meters.
Paper: THP2038
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2038
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP2041
Chicane-free laser heater system for mitigation of microbunching instability in linac-FELs
3519
We introduce a closed-form, verified through numerical integration, of the beam energy spread induced by oblique electron-laser interaction in a short undulator, so-called chicane-free laser heater. This scheme is relevant for high repetition rate free-electron lasers, space constrained, or subject to microbunching instability induced by a standard laser heater chicane. A calculation of the instability gain with the proposed scheme is presented to demonstrate its feasibility.
Paper: THP2041
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2041
About: Received: 21 Apr 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP2043
Numerical and experimental benchmarking of microbunching instability with intrabeam scattering in linac-FELs
3523
The systematic comparison of two semi-analytical models of microbunching instability affecting electron beams in single pass or recirculating linear accelerators is reported. The comparison is comprehensive of numerous features of the instability, such as low and high gain contributions, either linearized or at second order, coherent synchrotron and edge radiation, Landau damping by transverse emittance and laser heater, investigated for single and double magnetic bunch length compression. The comparison is enriched by three different expressions – one of which is new – to calculate intrabeam scattering. The inclusion of this effect allows the recovery of agreement with published experimental observations, to date either in disagreement with theory, or in partial agreement by virtue of blind fitting of parameters.
Paper: THP2043
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2043
About: Received: 21 Apr 2026 — Revised: 19 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP2050
A comparison between arc-like and chicane-like bunch compression for X-ray free-electron lasers
3540
The spectral brightness of a free-electron laser (FELs) is strongly dependent on the properties of the electron beam used to generate the radiation. Bunches used to drive FELs must have high currents, which are produced through longitudinal bunch compression. However, collective effects (such as coherent synchrotron radiation) degrade the emittance and energy spread during the bunch compression process, which in turn reduces the spectral brightness. A compression scheme for an FEL must be designed to reduce the impact of collective effects on the electron distribution in order to generate high spectral brightness FEL pulses. In this paper we compare commonly used four-dipole chicanes to two alternative bunch compressor configurations that are designed to mitigate coherent synchrotron radiation. We show that compression can be achieved with much reduced emittance degradation compared to 4-dipole chicanes in two cases: arc compression of positively chirped bunches, and 5-dipole compression of negatively chirped bunches. Each is suited to different FEL schemes.
Paper: THP2050
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2050
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2054
Top-up safety simulations for the Diamond-II storage ring upgrade
3552
Top-up operation at the Diamond-II storage ring will involve injecting bunches of electrons into the ring whilst the photon beamlines are in use. It is important, for the safety of the users, that electrons from the newly injected bunches cannot travel down the photon beampipe to the front end. For each beamline, all possible trajectories through the ID straight were identified and tracked through the machine to determine if any combinations of magnet settings exist that would simultaneously allow for stored beam and for electrons to be extracted through the front end. The full range of strengths for all the magnets/kickers were considered to account for any magnet power supply failures or different operating modes. Here we present the method used to track the electrons, summarise the results for the beamlines simulated so far and describe the interlocks required to ensure safe operation.
Paper: THP2054
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2054
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP2058
Impact of injection error on EUV FEL performance in an APL-based beamline
3568
Recent advances in laser-plasma accelerators (LPAs) have generated high-quality electron beams characterised by high peak currents and low emittance, making them suitable for powering compact, next-generation free electron lasers (FELs). However, variations in laser performance from shot to shot cause mismatches in position and angle at the injection point, complicating efficient beam transport and stable FEL operation. To preserve the electron bunch quality during beam propagation through a specialised, compact transport system, an active plasma lens (APL) can be used as part of the capture mechanism. This report investigates how injection errors influence electron beam properties along the beamline and their subsequent effect on FEL radiation in the extreme-ultraviolet (EUV) range. The results demonstrate an acceptable range of injection errors, including the mismatching effect, and emphasise the strengths and limitations of APLs as capture systems for optimal FEL performance. Various correction methods are analysed to minimise the impact of these injection errors. This work emphasises the potential of APL technology to develop compact FELs and improve LPA beam applications. Such progress is vital for future FEL facilities at ELI ERIC in the Czech Republic and for the EuPRAXIA project.
Paper: THP2058
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2058
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP2065
Experimental study of reverse tapering and resonance detuning in a seeded X-ray FEL
3572
Reverse tapering can suppress the FEL field while preserving electron microbunching for downstream radiators over an appropriate range of taper strength. In a monochromatically seeded FEL, one-dimensional small-signal theory suggests that the response to reverse tapering can be compared with the response to an accumulated resonance detuning. Here, we report on an experimental investigation of the relationship between undulator reverse tapering and resonance detuning in a seeded hard X-ray FEL, where the fixed seed frequency eliminates the influence of SASE photon-energy jitter. A modulator-radiator configuration was used in which U19 to U24 were scanned either by changing the resonance setting or by applying reverse tapering, while U25 was kept as the downstream radiator. The scans were performed with U25 active, to characterize the bunching-driven radiator signal, and with U25 off, to characterize residual upstream radiation. The U25-active spectra comparison shows a good agreement between reverse tapering and resonance detuning. The U25-off spectra show a stronger reduction of residual upstream radiation on the negative-detuning side than the U25-active radiator signal, indicating that the radiation field is suppressed more efficiently than the bunching-related signal, as expected for reverse-taper operation.
Paper: THP2065
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2065
About: Received: 12 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2067
Investigation of thermal degradation and stability in multi-alkali antimonide photocathodes: NaKSb (Cs) vs KCsSb
3576
Multi-alkali antimonide photocathodes have emerged as promising photoemissive materials for electron sources in high-repetition-rate free-electron laser (FEL) applications due to their low thermal emittance and high quantum efficiency in the green wavelength region. To evaluate their feasibility for operation in high-gradient RF guns, a collaborative effort between DESY-PITZ and INFN-LASA was initiated to develop and characterize multi-alkali photocathode materials under operative condition. As part of this effort, a NaKSb(Cs) photocathode belonging to the multi-alkali antimonide family was grown on a molybdenum substrate using a sequential deposition method in the new preparation system at INFN-LASA. A thermal degradation study of this photocathode was conducted, and its behavior was compared with a KCsSb film. This contribution presents the experimental results of the NaKSb(Cs) photocathode, focusing on its thermal degradation behavior and comparative analysis with the KCsSb photocathode.
Paper: THP2067
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2067
About: Received: 18 Apr 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
THP2069
Compensating The Effect of Asymmetrically Placed Undulators in FODO Lattices
3580
The dynamical focusing of FEL undulators with variable gap in FODO lattices with varying but overall low energy is detrimental the FODO optics. In the absence of compensation by adjusting the FODO quadrupole strengths it may drive the cell unstable. Typical examples of FELs in the critical regime are FLASH at DESY and the SXFEL-SBP at the Shanghai Synchrotron Radiation Facility. Before, in our contributions to FEL 2024 and IPAC 2025 we have extensively discussed the case where the undulators are centered inside the FODO drift of a Lattice with symmetric FODO cells. Here we treat the fairly common case where the drifts on each side of the undulator are unequal, which has significant impact on the compensation strategy and stability issues.
Paper: THP2069
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2069
About: Received: 11 May 2026 — Revised: 13 May 2026 — Accepted: 14 May 2026 — Issue date: 22 May 2026
THP2073
Upgrade of the high repetition rate FEL FLASH to allow simultaneous SASE and external seeding operation
3592
The Free-Electron Laser FLASH at DESY has provided more than 20 years XUV and soft x-ray SASE radiation for user experiments. In order to keep FLASH as a state-of-the-art FEL, the refurbishment and upgrade project FLASH2020+ was launched. The latest upgrade has been a complete replacement of the FLASH1 beamline in a 14 months shutdown in 2024/25. The new external seeded FLASH1 will provide fully coherent radiation at up to MHz bunch repetition rate (burst). Moreover, the new APPLE-III type undulators enable full polarization control. In addition, FLASH1 hosts, as before, a THz source. FLASH2 continues unchanged in SASE operation. The commissioning of the upgraded facility started in August 2025, and since November FLASH2 is back in user operation. Commissioning of seeding at FLASH1 continues in parallel to FLASH2 user experiments.
Paper: THP2073
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2073
About: Received: 12 May 2026 — Revised: 19 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP2076
Quasi-Steady-State Microbunching from multi-turn laser modulation at the Metrology Light Source
3596
Steady-state microbunching (SSMB) has been proposed as a scheme to generate high average power coherent synchrotron radiation at short wavelengths from an electron storage ring. To evaluate the feasibility of this scheme, a proof-of-principle experiment is conducted at the Metrology Light Source (MLS) in Berlin, the first phase of which (PoP I) was concluded in 2024. PoP I utilized a single-shot laser system to provide an energy modulation to the electron beam and investigated the fundamental requirements on storage ring dynamics to enable SSMB. Recently, the second phase of the SSMB proof-of-principle experiment (PoP II) has commenced at the MLS, in which a high repetition rate phase-locked laser system provides turn-by-turn energy modulation of the electron beam on consecutive revolutions around the storage ring. The main goal of SSMB PoP II is to show electrons can be confined to individual microbuckets defined by this laser interaction, reaching a quasi-steady state. This paper presents the first results obtained in SSMB PoP II, where coherent synchrotron radiation has been detected following multi-turn laser modulation, and the ongoing systematic studies of the underlying microbunching process.
Paper: THP2076
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2076
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP2078
The attosecond technology program at the European XFEL
3600
In this contribution we will discuss the “Attosecond Technology” program at the European XFEL. This strategic program is being launched to cross a new frontier in ultrafast science, enabling experiments that probe and control electron dynamics on their natural timescales. The program is structured into tightly coordinated projects that address the full chain of challenges required for reliable attosecond operation at the European XFEL. These include the following three areas: first, attosecond pulse generation; second, development of next-generation diagnostics, capable of resolving sub-femtosecond temporal structures and, third, dedicated proof-of-principle experiments to validate performance under real experimental conditions and to provide increasing user access to attosecond-class capabilities. These efforts form a roadmap that integrates accelerator physics, FEL science, and experimental methodology. The program aims at delivering reproducible and well-characterized high-power X-ray attosecond pulses in single pulse, X-ray pump/X-ray probe or Optical pump/X-ray probe configuration.
Paper: THP2078
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2078
About: Received: 08 May 2026 — Revised: 20 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP2082
Study of beam dynamics in magnetic electron buncher for Novosibirsk free electron laser
3603
Many applications of accelerator technology require electron bunches with length of up to 1 ps, the peak current exceeding 1 kA and the normalized emittance being less than 100 mm·mrad. To produce such bunches, special electron-optical systems ensuring beam bunching, known as magnetic bunchers, are widely used. Designing a 540° magnetic buncher has started several years ago at BINP [1]. Such a device enables users to obtain extremely short bunches with large charge. Effective bunching is ensured by the particularly strong dependence of the time of flight on the particle energy. In addition, for reduction of the maintenance costs, the whole electron-optical system is based on permanent magnets. This paper presents a brief review of the current state of the buncher design and the impact of space charge on transverse beam dynamics in electron optical elements of the device under construction.
Paper: THP2082
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2082
About: Received: 16 Apr 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
THP2084
SwissFELplus: a Mid-Term Upgrade Plan for the Swiss Free-Electron Laser
3606
SwissFEL, the free-electron laser facility at the Paul Scherrer Institute (PSI) in Switzerland, is about to complete its first decade of user operation. The knowledge gained during this period, together with important developments at FEL facilities worldwide, suggests a number of key upgrades to the accelerator and undulator complex that would substantially enhance the scientific capabilities of the two existing SwissFEL beamlines. The SwissFELplus project, planned for 2029-2032, aims to implement these upgrades - including full coherence in the hard- and soft-X-ray regimes via self- and external-laser seeding, as well as preparations for a new beamline - and thereby bring SwissFEL to a new level of scientific excellence ahead of its quantitative expansion with a third beamline. The resulting improvements in beam stability and coherence will benefit applications ranging from atomic physics to biology and will enable new approaches, such as quantum optics for X-rays, with its advantages in the management of radiation damage. This contribution describes the upgrade elements and their expected impact on SwissFEL’s photon-science capabilities.
Paper: THP2084
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2084
About: Received: 13 May 2026 — Revised: 13 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
THP2086
RF system upgrade of ELSA electron linac at CEA
3610
ELSA electron linear accelerator, operated at CEA/DAM for over three decades, is currently undergoing a major upgrade of its RF accelerating structures with the objective of enhancing operational reliability, availability, and performance. The first phase targeted the second accelerating stage and involved the replacement of the 433 MHz klystron modulator. The new modulator, developed by Jema Energy, is based on a high-voltage Marx architecture designed to enhance pulse stability and overall system maintainability. The second phase focused on the first accelerating stage, which feeds the 144 MHz photo-injector. The original tetrode-based RF amplifier has been replaced by a high-power solid-state amplifier developed by AMPEGON, capable of delivering up to 1.6 MW peak power. A key challenge of this upgrade was achieving an architecture with a comparable footprint and thermal management constraints to the former tube-based system while preserving RF performance specifications. The upcoming third phase will undertake a complete redesign of the RF system powering the 1.3 GHz third accelerating stage, including the development of new accelerating cavities and their associated high-power RF source. This contribution provides an overview of the upgrade program, detailing the design considerations, testing, commissioning, and integration activities. It also discusses the technological choices implemented and the operational experience gained throughout the process.
Paper: THP2086
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2086
About: Received: 11 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2087
PITZ Facility after the Upgrade: High Brightness Beams for Photo Injector R&D and feeding THz and Radiation Biology Experimental Stations
3614
At the Photo Injector Test facility at DESY in Zeuthen (PITZ) 22 MeV, high brightness electron beams are generated to serve mainly as a test facility for e.g. the European XFEL. Low emittance beams with bunch charges of less than a pC up to several nC are generated in an L-band photogun, which can provide bunch trains (4.5 MHz bunch repetition rate) of up to 1 ms in length at 10 Hz repetition rate. The three pillars of operation are: 1) R&D on high brightness photoinjectors for European XFEL: Main work topics are photocathodes, laser pulse shaping, machine learning, and operations improvements. 2) THz SASE FEL: Beams with a bunch charge of up to several nC are transported through an undulator to generate THz radiation at wavelengths around 100 µm with pulse energies of more than 100 µJ. Characterization of the THz output includes a FTIR spectrometer, a THz camera and a Michelson interferometer. 3) Radiation biology: In a second beamline the electron bunches are transported through a thin exit window to an in-air experimental station for *in vitro* and *in vivo* irradiations providing ultra-high dose rates over a worldwide uniquely wide parameter range, with the goal to systematically study the FLASH effect in order to find the underlying principle, which is yet unknown.
Paper: THP2087
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2087
About: Received: 11 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
THP2093
Finding operation conditions for ultra-high dose-rate electron beam delivery at FLUTE
3618
The linac-based test facility FLUTE (Ferninfrarot Linac- und Test-Experiment) at the Karlsruhe Institute of Technology (KIT) was designed to operate over a broad range of beam parameters and to generate ultra-short electron bunches. This versatility enables studies beyond accelerator physics, including applications in medical research. In particular, FLUTE can be used to explore operation modes suitable for investigating the effects of ultra-high dose-rate radiotherapy (FLASH RT) compared to conventional radiotherapy. Achieving the required dose rates for both modalities involved adjusting key beam parameters such as charge, repetition rate, and transverse size. This contribution discusses the strategies used to reach these conditions, the encountered technical challenges, and the results of initial tests on the achievable dose-rate ranges.
Paper: THP2093
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2093
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP2096
RF phasing for ELI-GBS linear accelerator
3626
The RF linac for the ELI - Gamma Beam Source (ELI-GBS) is being installed in Bucharest-Magurele (Romania). TW accelerating structures and SLED cavities are powered by klystrons via waveguide network that includes directional couplers for power monitoring and feedback. Before RF conditioning can begin, the linac must be properly tuned in terms of the RF phase and frequency. The waveguide system was reviewed with respect to its electrical length to ensure correct RF phase tuning. This work was carried out after installation but prior to connecting the waveguides to the accelerating structures. Fine RF-phase adjustments will be achieved through mechanical deformation of the waveguides. Since each klystron feeds four structures, the waveguides must be tuned so that the RF phase at the entrance of each structure matches its longitudinal position in the accelerator. Considering the fact that only 5-degree deviation in phase can be compensated by mechanical deformation of waveguides, larger discrepancies must be corrected physically by bending existing waveguide components to correct position or even reposition accelerator segments. Therefore precise analysis of the waveguide network was performed using a network vector analyzer. This paper reports the results of phase measurements performed on the assembled waveguide system. In addition, directional couplers were individually tested with VNA to verify their performance before integrating them into the system.
Paper: THP2096
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2096
About: Received: 16 Apr 2026 — Revised: 16 May 2026 — Issue date: 22 May 2026
THP2101
A semi-analytic, matrix-based model for the beam arrival time jitter
3633
The beam arrival time jitter is an important parameter for many advanced electron accelerators, including next-generation XFEL drivers. Accurate jitter modelling is particularly important during the design of a new facility, where it is often used to determine the tolerances of the RF sources and photoinjector laser. Conventionally, jitter is modeled using computationally intensive start-to-end simulations; in this approach, the entire accelerator is simulated many times, while the parameter associated with each jitter source is varied within its expected tolerance. This approach is time-consuming and scales poorly with the size and complexity of the accelerator. Semi-analytic jitter models therefore have significant advantages, owing to their speed and greater insight into the underlying physics. In this contribution, we propose a simple matrix-based model for the arrival time jitter in a linear accelerator with an arbitrary layout. We validate the model against simulations of CLARA at Daresbury Laboratory, and use it to explore the jitter tolerances of different operating modes.
Paper: THP2101
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2101
About: Received: 12 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2102
HIGH QUANTUM EFFICIENCY ALKALI-ANTIMONIDE PHOTOCATHODES FOR PERLE HIGH CURRENT DC GUN
3637
Modern particle accelerators, while enabling cutting-edge research, face major challenges in energy efficiency and beam intensity. The PERLE (Powerful Energy Recovery Linac for Experiments) project, developed at IJCLab/CNRS, aims to demonstrate a high-current energy recovery linac (ERL) using superconducting RF technology. By recovering the beam energy after use, PERLE drastically reduces RF power consumption and cryogenic load, paving the way for sustainable, high-performance accelerators. A key element is the development of alkali-antimonide photocathodes, combining high quantum efficiency and low thermal emittance. CsK₂Sb photocathodes, in particular, show excellent response to visible light, enabling operation with lower laser power and improved beam quality. Their fabrication relies on a unique deposition system equipped with a dedicated transfer line that links the glove box—where precursors are prepared—to the molecular beam epitaxy (MBE) chamber for growth, and ultimately to the electron gun for installation. Preliminary tests at IJCLab achieved a quantum efficiency of 3 %, validating this integrated approach for high-current ERLs such as PERLE.
Paper: THP2102
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2102
About: Received: 05 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
THP2104
High current photogun for the energy recovery linac PERLE
3640
In an Energy Recovery Linac (ERL), the beam, after acceleration and interaction, is recirculated and decelerated in the accelerating cavities of the linac. In such a scheme, the power of the beam is recovered within the SRF cavities, leading to substantial savings in electrical power. PERLE (Power Energy Recovery Linac for Experiments) is a high-power ERL demonstrator in Orsay, aiming to investigate multi-turn energy recovery. The electron beam can be recirculated in a superconducting linac up to 250 MeV (802 MHz). The high intensity electron beam (20 mA) is created by a photoinjector comprising a DC gun, a RF buncher, a SRF booster (7 MeV) and a merging section. The gun aims to produce 500 pC bunches at 40 MHz to inject the ERL ring with photocathodes of bi-alkali material (CsKSb). The photocathodes are deposited in a preparation facility (PPF) consisting of a molecular beam epitaxy (MBE) chamber for growth, linked via transfer lines to a glove box for precursor preparation and to the gun vacuum chamber. With this unique system, photocathodes can be prepared and loaded into the gun chamber under excellent vacuum conditions. Green light at 515 nm is used to produce electron bunch from the photocathode. The gun will be operated at 350 kV using as insulating gas N2 instead of SF6, a potent greenhouse effect gas. The photogun and its PPF, are installed at IJCLab- Orsay (France). The commissioning, currently underway, will be presented.
Paper: THP2104
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2104
About: Received: 12 May 2026 — Revised: 20 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP2106
The compton backscattering source COBRA at the S-DALINAC
3644
The COBRA source (Compton Backscattering at a Recirculating Accelerator) utilizes a 100 W Yb:YAG laser that is synchronized with the electron beam of the superconducting Darmstadt linear accelerator S-DALINAC * for head-on collisions. The backscattered photons in the X-ray energy range can be collimated into a quasi-monochromatic beam for electron beam diagnostics and as a technology demonstrator. The first collision of the electron and laser beam is planned in an upcoming beamtime with multi-turn recirculation. During operation, COBRA utilizes stabilization systems for both beams. Later, COBRA is foreseen to be operated during energy-recovery mode **, serving as a demonstrator for future Compton scattering light sources. This contribution provides an overview of the COBRA source, highlighting recent upgrades to the detector setup and developments of the laser beamline.
Paper: THP2106
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2106
About: Received: 01 Apr 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP2107
Installation and first tests of a High Brightness Beam Test Facility for ERL applications at INFN-LASA
3648
A High Brightness Beams Test Facility (HB2TF) has been funded in 2023 at the INFN-LASA laboratory in Segrate (Italy). The Test Facility will allow to perform developments in ERL design and to carry out experiments with a high current CW electron beam in frontier areas of accelerator physics. In this paper we will report the status of the project and discuss the first tests underway on the main elements involved and available.
Paper: THP2107
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2107
About: Received: 10 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP2116
Superradiant terahertz radiation generation at EuXFEL: from design to installation
3664
Accelerator-based THz sources offer high energy and repetition rates, making them attractive for pump-probe experiments at X-ray free-electron lasers. The superradiant terahertz radiation generation (STERN) experimental chamber was recently successfully integrated into the European XFEL electron beamline during its long installation and maintenance period. The setup incorporates Cherenkov wakefield structures and a diffraction radiation screen to generate superradiant terahertz (THz) pulses from the electron beam, covering a combined spectral range between 0.3-30 THz. This work describes the design and installation of the experimental hardware, with emphasis on the THz generation and transport components. It reports on the wakefield structure assembly, the 10 m transport line and the laser-based alignment of the elements inside the chamber.
Paper: THP2116
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2116
About: Received: 15 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2119
Characterization of THz radiation at FLUTE
3672
FLUTE, the Ferninfrarot Linac- und Test-Experiment at KIT, is a compact linac-based accelerator test facility and provides electron bunch energies up to several tens of MeV with a wide range of charges. A bunch compressor allows tuning the bunch length from picoseconds down to the femtosecond-scale. FLUTE can therefore generate short, intense THz radiation for a large variety of applications. In this contribution, we report on characterization measurements of THz radiation generated after the bunch compressor.
Paper: THP2119
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2119
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP2124
ELI-NP Gamma-ray Beam System - status update and future
3676
The high brilliance ELI – Gamma-ray Beam System (ELI-GBS) is under implementation at Extreme Light Infrastructure - Nuclear Physics (ELI-NP) in Romania. The system uses an 800 MeV S-band accelerator driver as an Inverse Compton Scattering (ICS) source coupled to an interaction laser and in the future to a high-finesse optical cavity. The γ-ray beam will be available with energies up to 19.5 MeV to drive an ambitious scientific program which requires high spectral density (larger than 5×10^3 photons/s/eV), narrow bandwidth of 0.5%, and linear polarization higher than 95%. The ELI-GBS is foreseen to be finalized in an initial configuration in 2026. Details of the status of the LINAC, interaction laser system, and challenges for completing the system will be highlighted.
Paper: THP2124
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2124
About: Received: 05 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2125
First demonstration of MeV electron diffraction using the superconducting RF photoinjector at the Helmholtz-Zentrum Dresden-Rossendorf
3679
Ultrafast electron diffraction (UED) allows for the characterization of structural and electronic dynamics in samples with sub-picosecond resolution. Utilizing a continuous wave photoinjector gives rise to MHz MeV UED, which has the benefits of better temporal resolution, higher beam coherence, higher resolution, and high repetition rates. A superconducting radiofrequency (SRF) photoinjector is part of the existing ELBE user facility at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), delivering electron beams in user operation since 2010. The HZDR is planning the construction of the Dresden Advanced Light Infrastructure (DALI), a source of positrons and IR and THz radiation. One of DALI's end stations will consist of the MeV UED facility, allowing to pump with IR and THz beams, and probe the samples with an electron beam, generated using an HZDR-type SRF photoinjector. In this proceeding, we present the first MeV electron diffraction results using the HZDR-type SRF photoinjector at ELBE.
Paper: THP2125
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2125
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2126
A commercial MeV-UED instrument based on a 2.5 cell RF-Photogun
3683
Current research in quantum, nano, and energy materials requires information about material structure on the atomic scale in space and time. These materials show a variety of ultra-fast phenomena such as light absorption, structural changes, phase transitions, thermal or non-thermal melting, all of which happen on the ps or sub-ps scale and involve position changes on the Ångström scale. In this contribution we present the conceptual design for the RI-Bornite instrument, which allows ultra-fast electron diffraction using Mega-electron-volt electron beams (MeV-UED). For this instrument we use a warm (copper) 2.5-cell RF-photogun with a replaceable Cu photocathode. A single Ti:Sa fs-laser system drives both the pump beam (266 nm, ca. 1 µJ) and the probe beam (800 nm, several mJ/pulse). The system is designed to reliably reach 100 fs temporal resolution. The current sample chamber is optimized for solid-state samples and includes the option for sample cooling and a load-lock. Future versions shall allow experiments on liquid or gaseous samples. We present the main design considerations, electron beam dynamics simulations, and the engineering design.
Paper: THP2126
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2126
About: Received: 18 Apr 2026 — Revised: 20 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
THP2128
Variable sample illumination and angular magnification for the RUEDI ultrafast electron diffraction beamline
3686
The RUEDI (Relativistic Ultrafast Electron Diffraction & Imaging) ultrafast electron diffraction (UED) beamline aims to deliver MeV electron bunches for sub-10 fs timescale diffraction experiments. The achievable resolution of the diffraction pattern at the detector is determined by the quality and focusing of the beam at the sample, and the transport of the scattered beam to the detector. A beamline design is presented which allows for flexible illumination onto the sample and variable angular magnification. The pre-sample electron optics consists of two apertures and two single solenoid lenses followed by the post-sample optics which consists of two double solenoid lenses. Simulated results are used to demonstrate the range of capabilities of each system and show that RUEDI will be capable of producing the high-resolution diffraction patterns needed for a world-leading UED machine.
Paper: THP2128
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2128
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP2130
From Cs3Sb to Cs2Te photocathodes on ELSA accelerator at CEA DAM
3694
The 19 MeV electron linear accelerator ELSA at CEA DAM operated as an IR‑FEL in the 1990s and is now a user facility that provides pulsed bremsstrahlung and Inverse Compton Scattering (ICS) X‑rays. Renovation of the facility is currently under way to improve system reliability. The 144 MHz photo‑injector gun is the key element for producing a low‑emittance beam for the ICS X‑ray source. While the refurbishment of the 144 MHz RF source has increased the photo‑injector’s reliability, the short lifetime of the photocathodes has become the facility’s weak point. A first step toward higher beam availability for users is to replace the Cs₃Sb photocathodes with Cs₂Te, which is known to have a longer lifetime. The drawback of this material is that it requires illumination with UV light, resulting in less laser energy available for photon‑to‑electron conversion compared with visible‑light operation. This paper will present the fabrication process, compare the two materials in terms of quantum efficiency and lifetime, and describe the laser‑system upgrades needed to maintain the same electron‑beam current.
Paper: THP2130
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2130
About: Received: 11 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP2131
Production and Initial Testing of a Nanostructured Copper Photocathode in an S-Band RF Gun
3698
A copper photocathode based on bulk Cu(100) substrate with a 50 𝜇m-diameter nanostructured region was fabricated and integrated into an S-band radio-frequency gun. We report the procedure for production and preparation of high- quality copper cathodes with nanostructured area compatible with state-of-the-art S-band RF gun. Experimental results indicate absence of increased dark current up to 70 MV/m at the cathode.
Paper: THP2131
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2131
About: Received: 12 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2134
Photocathode development plan for DALI multifunctional facility
3708
DALI is an accelerator-based terahertz (THz) light source that uses multiple superconducting accelerators to drive CW electron bunches through undulators to emit ultra-intense THz pulses, including two ELBE SRF photo injects as the e- sources for high bunch charge beamline and for the UED, respectively. It requires a versatile portfolio of photocathodes to support diverse electron gun configurations and beam parameters targets. For the SRF gun commissioning, robust polycrystalline copper cathodes and magnesium cathodes will be employed, providing reliable performance and simplified handling during initial RF conditioning. Beam commissioning and routine user operation will firstly rely on the mature Cs₂Te photocathode, chosen for their proven robust, stability and realiable quantum efficiency. To enhance operational flexibility, especially in scenarios where UV laser generation presents challenges for special user appliations, we will consider to apply high-efficiency “green” photocathode optimized for visible-wavelength drive lasers. In parallel, an ultra-low-emittance photocathode in tens of micrometers will be under investigation to meet the stringent beam quality requirements of UED applications. This multi-cathode strategy ensures reliable commissioning, user-friendly operation, and state-of-the-art beam performance across all beamlines of the new accelerator facility.
Paper: THP2134
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2134
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
THP2135
Status of the automated activation of GaAs photocathodes at Photo-CATCH*
3711
Photocathodes based on the III-V seminconductor GaAs are used as photo-electron sources to supply spin-polarized electron beams for accelerator applications. In order to achieve a sufficient electron yield, a thin surface layer of cesium combined with an oxidant is applied onto the cathode surface in a process called the cathode activation. It is typically done manually by an experienced operator. This contribution presents the current status in the development and testing of an adaptive algorithm for automated activation at the Photo-CATCH test stand.
Paper: THP2135
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2135
About: Received: 15 Apr 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
THP2136
Photoemission study of nanostructured plasmonic photocathodes
3714
We present a simulation study of a nanostructured plasmonic copper photocathode for use in the new photoinjector that is presently being developed for the high-duty-cycle operation upgrade of the European XFEL. The simulations are based on a spatially resolved photoemission model using the Fowler-DuBridge formalism and including the Schottky effect induced by the accelerating field on the cathode surface. Particle-in-cell simulations are performed to evaluate the phase-space of the beam in the near-cathode region. It is shown that while quantum efficiency is improved, photoemission from the plasmonic cathode leads to a substantially increased transverse emittance and higher energy spread of the beam compared to the case of a flat copper surface. Space-charge effects remain moderate for the operating bunch charge considered in the study.
Paper: THP2136
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2136
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP2137
Status of the hybrid electron gun development at ELSA
3718
A redesign of the injector beamline for the S-band linac at ELSA is underway, including the replacement of the existing electron gun by a hybrid gun that combines thermionic emission and thermally assisted photoemission in a single setup. The goal is to offer a new single-bunch injection mode alongside the long pulse mode already provided by the current gun. Measurements have been conducted to verify this emission technique using caesium dispenser cathodes. Another step in the scope of the project is the replacement of the current prebuncher cavity. A new design has been worked on and already undergone different tests of quality factor and bunching capabilities. The development of a dedicated test stand is currently being carried out to facilitate more detailed studies and serve as a prototype for the future injector section. Recent work has concentrated on the lattice and magnet design, as well as on evaluating suitable beam-diagnostic instrumentation.
Paper: THP2137
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2137
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP2139
A time-resolved high charge density electron photoemission model for the FCC-ee top-up scheme
3721
The generation of ultrabright electron beams relies on photo-injectors, which are influenced by dynamic surface and collective field effects. Predicting the resulting bunch characteristics is complicated due to the superposition of RF field, near cathode image-charge field, and space-charge. These effects are particularly relevant in high charge density photo-injectors operating with sub-ps bunch duration and nC bunch charge. We present an extended Fowler–Dubridge–canonical photoemission model that incorporates self-consistenly the temporal evolution of the aforementioned surface electric fields. We perform this connection by dynamically coupling the resulting fiends and the Schottky barrier. This method links single-particle photoemission physics with collective field effects, enabling the prediction of quantum yield in real time. Our simulations reveal strong spatio-temporal modulation of the photoemissive process, inducing nonlinear collective forces that degrade beam quality through emittance growth and phase-space distortion. The results underscore the important role in shaping the initial laser pulses to tailor the phase space of electron bunches for future colliders.
Paper: THP2139
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2139
About: Received: 13 Apr 2026 — Revised: 14 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP2141
Design, realisation, and high-power operation of the first Travelling-wave Photo-emission Electron Gun
3725
A novel travelling-wave (TW) RF photogun driven by ultra-short RF pulses has been successfully tested, stably reaching cathode fields of 170 MV/m for 100 ns pulses and 190 MV/m for a 10 ns pulse. This cathode surface electric field gradient far surpasses current S-band photoguns and represents a significant step toward increasing the brightness of future XFELs. Here we present an overview of the RF design, its unique tuning-free implementation, and highpower performance, highlighting how TW RF Photogun technology opens new opportunities for advanced electron sources.
Paper: THP2141
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2141
About: Received: 15 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP2143
Delivery of caesium telluride photocathodes to the CLARA accelerator at Daresbury Laboratory
3729
High performance electron accelerators require high brightness electron beams. To achieve this a photocathode with a high quantum efficiency (QE) and low intrinsic emit- tance is required while also being robust with a long lifetime and low dark current. Photocathodes based on alkali metals can fulfil these requirements and, as such, are an important area of research for the accelerator physics community. The Compact Linear Accelerator for Research and Ap- plications (CLARA) at STFC Daresbury Laboratory has recently been upgraded from a copper photocathode to a cae- sium telluride photocathode. This has enabled a significant increase in bunch charge for a fraction of the laser power. We discuss the process of manufacturing and polishing molyb- denum photocathode plugs and the subsequent deposition of caesium telluride thin films. Three photocathodes have been provided to the CLARA facility with consistent and high quantum efficiency. One of these photocathodes has been successfully operating in CLARA since September 2025 with a stable QE of approximately 11 %.
Paper: THP2143
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2143
About: Received: 11 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP2154
Design, training and magnetic field characterization of the superconducting THz-undulator coils for FLUTE
3761
FLUTE, a short-pulse linac and short-bunch THz test facility, serves as an accelerator test setup for a variety of accelerator physics studies. In its final stage of expansion, it is foreseen to provide coherent radiation in ultra-short, very intense light pulses in the terahertz and far-infrared spectral range. A superconducting undulator (SCU) at the end of the accelerator structure offers the possibility to generate photon radiation between 4 THz and 12 THz (energies between 16.5 meV and 50 meV) with a high pulse energy. This energy range, for instance, is of interest for studies of water-soluble interactions. The final undulator design was carried out by Bilfinger Nuclear & Energy Transition GmbH (BNET) in close collaboration with the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT). Before assembling the final undulator device the superconducting coils were trained and magnetically characterized in CASPER II, a magnetic measurement setup which is part of the Magnet and Cryogenics Facilities (MCF) at the IBPT at KIT. In this contribution we describe the general SCU layout, presenting the results of the coil training, the local magnetic field characterization and field integral minimization of the THz-undulator coils.
Paper: THP2154
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2154
About: Received: 12 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP2157
Demonstration of a transverse gradient undulator in an X-ray free-electron laser
3772
Modern synchrotron light sources employ various types of undulators to generate highly coherent and well collimated X-rays. A large and homogeneous magnetic field around the beam axis is typically the preferred configuration, since it simplifies both alignment and operation. Nevertheless, a nonhomogeneous field, such as that of a transverse gradient undulator (TGU), offers attractive possibilities for advanced operating modes, for example enabling large bandwidth operation in a free electron laser. In this contribution, we present the first beam-based characterization of such a TGU for various magnetic field gradients and X-ray polarization settings, and we compare the experimental results with corresponding simulation data. The measurements were carried out at Athos, the soft x-ray beamline of SwissFEL. This line employs Apple X undulators, whose independent radial and shift motion of all four magnetic arrays makes them uniquely capable of generating the required transverse gradients.
Paper: THP2157
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP2157
About: Received: 18 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP3004
Hybrid optimisation of THz-driven tapered waveguides for synchronous acceleration of weakly relativistic high-quality electron bunches
3785
Downscaling particle accelerators is crucial to expanding their range of applications. Dielectric-lined waveguides (DLWs) can support hybrid modes with a strong accelerating component. Excited by terahertz (THz) frequency pulses, DLWs can deliver high accelerating gradients over cm-scale interaction lengths, promising the development of future compact electron accelerators. By precisely tailoring the waveguide geometry, the modal field profile and phase velocities can be tuned to maintain synchronisation between the weakly relativistic bunches and the accelerating mode over extended distances. Here, we design and evaluate THz-driven tapered DLWs delivering high-quality, MeV-level electron bunches in two types of symmetrical DLW waveguides: rectangular and cylindrical. We use analytic models of accelerating modes to simulate transport and acceleration of an externally injected 100-keV electron beam across various DLW geometries. A genetic algorithm is employed to identify Pareto-optimal geometries based on the final bunch characteristics.
Paper: THP3004
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3004
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP3325
High-gradient radiofrequency photoinjector with a detachable cathode Assembly
3812
We present an RF photoinjector architecture that utilizes the TM$_{02}$ mode in the first half-cell housing the cathode. Unlike the conventional TM$_{01}$ mode configuration, this design introduces a controlled discontinuity in the surface field, producing a region free of surface currents. This unique topology allows the cathode to be mechanically separated from the gun body without compromising RF performance or requiring precise electrical continuity at the interface. The photoinjector should, in principle, deliver a very high cathode gradient and, consequently, high beam brightness. At the same time, the detachable cathode assembly is compatible with load-lock systems, which can transfer high QE semiconductor cathodes into high-gradient RF photoinjector structures under UHV.
Paper: THP3325
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3325
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP3604
Dual-pillar dielectric laser acceleration structure for relativistic electrons
3818
Dielectric-laser accelerator (DLA) can provide accelerating gradients on the order of GV/m and is therefore considered a promising alternative to conventional radio-frequency accelerators. Extending DLA to relativistic electrons is still at an early stage and this research is important for achieving fully miniaturized accelerators. In this paper, we optimize dual-pillars DLA structures and evaluate their performance through numerical simulations. The results indicate energy gain for individual relativistic electrons as well as for a relativistic electron bunch. The simulation results will be used as guidance for the fabrication of the structures and the upcoming acceleration experiments.
Paper: THP3604
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3604
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP3605
Design of a dielectric laser accelerator structure for low β charged particles
3822
Dielectric laser accelerator (DLA) is a novel acceleration scheme using dielectric nanostructures with high damage thresholds for the laser electric field. In DLA, the typical structural period is determined by the product of the Lorentz factor β and the laser wavelength λ. At low β, the structural period becomes extremely small, making fabrication impractical and limiting the range of initial energies that can be accelerated. In fact, DLA has so far been demonstrated only for initial energies above approximately 10 keV [1–3]. We design DLA structures that extend the range of initial kinetic energy that can be accelerated to lower energies. By setting the structural period to an odd multiple of βλ and specifically employing a 3βλ structure in this work, the fabrication constraints associated with low initial energies can be improved. As a result, acceleration is driven by enhanced third-order Fourier components of the laser field generated during transmission through the pillars, rather than by the original incident laser component. In this presentation, we will report on a pillar cross-sectional design capable of accelerating low-energy electrons (5 keV) based on acceleration simulations.
Paper: THP3605
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3605
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP3614
Development and characterization of a FEBIAD ion source for RI beam production at the RAON ISOL system
3829
RAON is a heavy-ion accelerator facility in Korea that uniquely combines ISOL (Isotope Separation On-Line) and In-Flight (IF) techniques to produce a wide range of Rare Isotope (RI) beams. In the ISOL system, ion sources are continuously being developed to expand RI beam production capabilities. Among them, the Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source is a promising candidate for efficient RI beam generation. A prototype FEBIAD ion source was evaluated at the offline facility, where successful Ar, Kr, and Xe isotope beam extraction demonstrated its operational feasibility. Since the FEBIAD ion source operates at elevated temperatures, structural deformation due to thermal expansion can occur. In particular, bending and variations in the gap between the anode grid and cathode have been identified as critical issues. To mitigate these effects, a new FEBIAD ion source design was developed and fabricated to ensure structural stability under high-temperature conditions by adding a heating strip and allowing the body to slide. The fabricated ion source successfully achieved Kr isotope beam separation in offline tests, and subsequent online experiments confirmed stable operation of the source under ISOL conditions, demonstrating its suitability for reliable RI beam production. Future work will involve RI beam extraction experiments using various targets within the RAON ISOL system.
Paper: THP3614
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3614
About: Received: 12 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP3616
Cavity geometry optimization for multipactor suppression in a VHF CW electron gun
3833
VHF CW photocathode electron guns suffer from severe multipactor effects that significantly degrade their operational performance. In this work, the RF cavity geometry was optimized via CST simulations to suppress multipactor, employing a three-phase strategy with fixed key structural parameters. Compared with the SHINE gun baseline, the optimized cavity achieves a much lower multipactor growth rate $\alpha$ while preserving excellent high-performance RF characteristics. This demonstrates that geometry optimization is an effective approach to mitigate multipactor in VHF CW photocathode electron guns.
Paper: THP3616
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3616
About: Received: 06 May 2026 — Revised: 19 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP3617
Initial beam characterization from a cold field emitter in a VHF electron gun
3836
High-quality electron beams are critical for imaging experiments that provide detailed microscopic structural insights into materials. The Very-High-Frequency electron gun, capable of operating in continuous and pulsed modes, is a preferable option. In this paper, we employ a tungsten tip with an apex radius of curvature approximately 100nm as a cold field emission cathode in the VHF gun and measure the beam charge, transverse emittance, and energy spread to characterize the beam quality. In preliminary experiments, we have achieved a normalized transverse emittance of 54.01nm·rad. With an electron gun power of 37kW, we obtained astrongbeamcurrentofapproximately 6µA, which remained stable and continuous for several hours in a single experiment. By using an aperture to block electrons with large divergence angles and adjusting the solenoid’s focusing strength, we propose to converge the target-energy electron beam onto the aperture, increasing its transmission rate and optimizing the energy spread. Prior to optimization, the energy spread was approximately 3.57% at 536keV when using a 20µm diameter aperture.
Paper: THP3617
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3617
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP3621
4K Superconducting RF electron gun
3843
A superconducting accelerator is an excellent technology that can efficiently accelerate high-current beams and is being applied to free electron lasers and next-generation linear electron-positron colliders such as ILC. Not only for the fundamental science, but also the high current electron beam plays a rather important role in industrial and medical applications. This is because the demand for high-current beams is also strong in these applications. While superconducting accelerators are becoming more widely used, there are not many examples in practical use of the superconducting RF gun, such as the ELBE RF Gun in HZDR. The entire accelerator should be superconducting for its energy efficiency and technical compatibility. To bridge this technical gap, we propose a superconducting RF gun utilizing the latest 4K superconducting technology, which can generate continuous, high-brightness beams.
Paper: THP3621
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3621
About: Received: 16 Apr 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP3627
Non-resonant multipactor mechanism and SEY impact in VHF CW electron gun
3847
Multipactor in very-high-frequency (VHF) continuous-wave (CW) electron guns threatens stability, with non-resonant behavior and secondary electron yield (SEY) as key factors. This study clarifies non-resonant multipactor arises from weak local electric fields and disrupted electron-field resonance. It compares SEY models and adjusts the Furman model to match practical conditions. Combined with the optimized cavity, the adjusted SEY model reduced $\alpha$ to near-zero, eliminating multipactor. Particle analysis also showed multipactor concentrates on the anode side. This work provides a comprehensive solution for VHF gun multipactor risks.
Paper: THP3627
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3627
About: Received: 16 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP4021
Heavy ion focusing using a Gabor Lens inside a drift tube structure
3907
Space-charge lenses based on confined non-neutral plasmas, such as electron clouds, provide strong, axially symmetric focusing for high-intensity ion beams and serve as an alternative to conventional quadrupole magnets. The so-called Mobley drift tube integrates a Gabor-Lens (GL) into a drift tube of a linear accelerator, enabling beam focusing within an accelerating RF structure. The confined electron cloud does not come into direct contact with the accelerating field; a re-entrant snout geometry is introduced and optimized to minimize the RF field amplitude in the region where the electron cloud forms. Confinement of sufficiently high electron density is achieved in the beam pipe of the drift tube without any external electron source, relying solely on self-sustained processes. This contribution presents simulations and RF measurements of an RF- and vacuum-compatible prototype Mobley drift tube designed for heavy-ion beams, providing insight into the operational feasibility and focusing performance of Gabor-lenses integrated in LINAC drift tubes.
Paper: THP4021
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4021
About: Received: 12 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP4039
Overview of the ESS neutrino Super Beam Plus Project
3952
The ESS neutrino Super Beam (ESSnuSB) project aims to produce a highly intense, second-generation neutrino beam optimized for precision measurement at the second neutrino oscillation maximum, providing an enhanced capability to discover CP violation in the leptonic sector and to measure the CP violating phase with high precision. ESSνSB will be integrated into the ESS accelerator facility, which is originally designed to deliver a 2.0 GeV, 5 MW proton beam for neutron production, and will accelerate the additional pulses required for the neutrino production. By using interleaved pulses in ESS proton linac, the power will be effectively increased from 5 to 10 MW. This project has received funding from EU in the framework of Horizon Europe 2020 (2018-2022) and Horizon Europe (2023-2026) to carry out feasibility studies. Initial design studies-covering all parts from ESS proton linac up to the location of the neutrino far neutrino detector- are documented in the Conceptual Design Report (CDR). A continuation of this work, ESSnuSB+, aims to enable cross-section measurements and sterile neutrino searches. It proposes two low-energy facilities; nuSTORM, which produces neutrinos from muons decays in a storage ring, and ENUBET, which produces neutrinos from pion decays and monitors the neutrino beam by detecting the decay muons. An updated overview of the project will be given in this work.
Paper: THP4039
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4039
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
THP4044
Consolidation of the Antiproton Decelerator Electron Cooler
3964
A new electron cooler, replacing the 40 year old one, will be installed starting in 2027, during Long Shutdown 3, in the CERN Antiproton Decelerator ring. The new electron cooler aims to improve reliability, cooling time and beam losses. The design of the new electron cooler, very similar in geometry, electron intensity and energies to the present device, will add electron beam magnetic expansion from the gun to the cooling section and enhance the field quality in the cooling section so to reduce electron transverse energy; approach the H/V orbit corrector magnets and improve relative position measurement of the antiproton and electron beams so to better center the two beam; allow faster switching of the electron beam on/off at the gun so to ease operations. Ultimately, the testing strategy will ensure highly reliable operations. This paper presents an overview of the status of the project.
Paper: THP4044
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4044
About: Received: 12 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
THP4047
An upgraded extraction septum and a new diagnostic section for the Bonn isochronous cyclotron
3976
The Bonn Isochronous Cyclotron provides light ion beams of a charge-to-mass ratio Q/A >= 1/2 with kinetic energies ranging from 7 to 14 MeV/A to five experimental sites. To improve operation reliability, the cyclotron's electrostatic extraction septum is upgraded using components, manufactured by laser-powder bed fusion (L-PBF). The new copper septum blade holder reduces thermal load on the blade and the integrated cooling system's leak rates to the vacuum. Also, a new beam diagnostic section for the future ion beam analysis setup in Beamline D is under construction, comprising a secondary electron monitor, a Faraday cup (FC) and a beam screen (BS). Both, FC and BS, are made from aluminium using L-PBF and are pneumatically retractable. Cooling is provided through coaxial water tubes, integrated into the pneumatic rods. Here, progress of the septum upgrade will be reported and details of the new diagnostic section will be provided.
Paper: THP4047
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4047
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP4053
E-gun and test stand development for the pulsed electron lens for space charge compensation at GSI
3988
At GSI the design of a prototype electron lens to demonstrate space charge compensation in bunched ion beams is being continued. The ultimate goal is to increase the beam intensity for FAIR by compensating for the space charge forces in the synchrotrons operating with high intensity beams by overlapping with a pulsed electron beam in the electron lens. The development of the key components — e-gun and collector — is currently underway with the aim of installing them in the SIS18 e-cooler and demonstrating the concept for the first time. The conceptual design of the RF-modulated electron gun is completed, construction will start in mid 2026 and delivery is scheduled for autumn 2026. In the meantime, a test stand is being designed and will be set up at GSI to commission the e-gun and subsequently the collector. In this contribution, an overview of the ongoing activities regarding the details of the gun design, collector and the test stand set-up will be presented.
Paper: THP4053
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4053
About: Received: 11 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP4055
Confinement of Electron Clouds in a Bending Magnet
3992
Dipole-magnets in linear accelerators or synchrotrons are used to bend ion beams. In case of intense ion beams, space charge compensation is a strategy to overcome intensity limits. So far the reduction of the beams space charge is not investigated in bending magnets by experiments. Therefore, a Gabor-lens was constructed and immersed in a H-type bending magnet to provide a pure electron plasma. Usually, Gabor-lenses are ion optical devices used for focusing and deflecting ion beams. With the setup presented in this paper it will be possible to compare the bending of intense ion beams with and without space charge compensation. Furthermore, the impact of spontaneous built-up of electron clouds observed in synchrotrons can be studied. First experimental results compared with numerical simulations regarding the confinement of electron plasmas within the dipole-Gabor-lens system will be presented. First beam dynamic simulations will show the impact of space charge compensation within bending magnets.
Paper: THP4055
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4055
About: Received: 19 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP4059
Studies of transverse emittance growth of LHC-type beams on the long injection plateau of the CERN SPS
4002
Transverse emittance growth was observed during the long injection plateau for high-intensity multi-bunch LHC-type beams in the CERN SPS, showing a clear dependence on the working point. Transverse tunes were increased to reduce emittance growth driven by integer resonances; however, a residual increase in emittance persists. To characterize this behavior and investigate its possible causes, transverse profile measurements were performed with the SPS wire scanners at several points along the injection plateau. These measurements are used to quantify the evolution of the transverse emittances and to assess the presence and possible generation of overpopulated tails.
Paper: THP4059
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4059
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP4081
Space charge compensated ion beam extraction
4051
The generation of high intensity ion beams requires high density plasma in the ion source. Earlier studies have shown how high plasma densities can be achieved with a combined RF- and arc-discharge without using a filament as an electron emitter. While space charge compensation in the extraction region could benefit the space charge limited extraction of high intensity beam, in conventional extrac- tion systems however the compensating electrons need to be blocked from entering the extraction region by means of a suppression voltage to prevent sparking in the high voltage gap. Therefore we propose the controlled use of a separately produced electron beam to compensate space charge right at the extraction gap. The concept of achieving superposi- tion of electron and ion beam by propagating the e- beam through the plasma generator chamber is evaluated. First beam dynamics simulations for the electron beam as well as extraction studies for the compensated and non-compensated case are presented.
Paper: THP4081
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4081
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP4110
Towards the detailed design of the High Luminosity Large Hardon Collider beam dumps
4127
The High Luminosity (HL) upgrade of the Large Hadron Collider (LHC) requires the installation of two new beam dumps capable of safely absorbing energies of up to 710 MJ per beam. The beam dump consists of an 8.4 m long, 700 mm diameter, thin-walled cylinder containing a shrink-fitted internal core made of carbon-based materials. This contribution reports on the critical R&D activities supporting the detailed design of both the dump vessel and the carbon-based core. The vessel is constructed from Ti-6Al-4V (Grade 5) segments joined circumferentially by electron-beam welding. Extensive fatigue testing has been performed to validate the structural integrity of these welds under the severe vibrational loads induced by beam impact, complemented by fracture-toughness and fatigue-crack-growth characterisation. For the absorbing materials, the HiRadMat-65 experiment evaluated several candidate core materials under HL-LHC nominal and accident beam-dilution scenarios, with no observable damage, thereby confirming their suitability for HL operation. Together, these results represent key steps toward the final engineering design of the HL-LHC beam dumps. Research supported by the HL-LHC project.
Paper: THP4110
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4110
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP4117
Optimising the proton and electron transfer lines design for high-quality electron acceleration in AWAKE Run 2c
4149
The Advanced Wakefield Experiment (AWAKE) is developing a novel plasma-based accelerator concept in which self-modulated proton bunches generate wakefields capable of accelerating electrons to energies relevant for particle physics. Completed in 2025, the Run 2b experimental phase aimed to demonstrate wakefield-amplitude stabilisation after saturation of the self-modulation process via a plasma density step while establishing the experimental configuration needed for high-quality electron acceleration in Run 2c. In Run 2c, the goal is to demonstrate acceleration up to about 10 GeV while preserving the quality of the accelerated electron beam. To achieve this, a new configuration of the proton transfer line is under investigation to compensate for the bending introduced by the 150 MeV electron line dipole in the interaction region between the two plasma cells. In parallel, the experimental requirements for the 150 MeV electron line have evolved to minimise the physical gap between the two plasma cells, demanding an optimised focusing scheme to deliver a beam with a transverse size of a few microns into the second plasma section. A new design of the 150 MeV electron transfer line is therefore proposed, including detailed error studies to assess its robustness under realistic operational conditions.
Paper: THP4117
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4117
About: Received: 12 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP5305
Emittance measurements in the BTS transfer line at the Canadian Light Source
4192
During the injection process at the Canadian Light Source (CLS), approximately one third of the electron beam is lost from the Booster Ring (BR) to the Storage Ring (SR) at controlled locations in the Booster-to-Storage Ring (BTS) transfer line. In 2021, the BTS was upgraded to allow the facility to run in Top-Up mode. Included in this upgrade was the installation of new diagnostic CCD cameras in the transfer line with the intent to use them to measure beam properties and better understand the electron beam extracted from the BR. This paper presents emittance measurements, using these diagnostic cameras, of the electron beam extracted from the BR. Using two quadrupoles, one focusing and one defocusing, quadrupole scan measurements were performed to measure both the horizontal and vertical emittances in the BTS. An estimated emittance in the BR was also measured using a combination of images of the synchrotron radiation produced by the BR and betatron functions, dispersion, and energy spread values obtained from simulations. These emittances measured were then compared to expected theoretical emittances of the BR from synchrotron radiation integrals.
Paper: THP5305
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5305
About: Received: 07 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP5327
Studies of magnets misalignment in Ring-based Electron Cooler
4226
Performance of Electron Ion Collider (EIC) will benefit from cooling of protons at the highest collision energy (γ=294). The required cooling can be provided by the Ring Electron Cooler (REC) – a non-magnetized RF-based electron cooler, employing an electron storage ring. The REC is a “racetrack” consisting of a 170 m long cooling section (CS), a wiggler section opposing the CS and containing eighteen 2.4 T damping wigglers with highly nonlinear field profile, and two matching arcs. The REC utilizes an elaborate correction scheme to achieve the target dynamic aperture (DA) in the baseline lattice. Alignment errors in magnet placement will be present in a constructed ring and will disrupt the DA correction scheme. In this paper, we describe studies of alignment errors, their effect on the dynamic aperture, define tolerances to various misalignments and propose a procedure for misalignment correction.
Paper: THP5327
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5327
About: Received: 12 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP5328
Space charge dynamics in ring-based Electron Cooler
4229
The Ring Electron Cooler (REC) is designed to provide cooling to 275 GeV protons at Electron Ion Collider (EIC). The REC is a non-magnetized RF-based electron cooler employing a 150 MeV electron storage ring. Electron bunches of 21 nC are needed to achieve cooling rates required by EIC. The tune shift in the electron storage ring induced by e-bunch space charge (SC) is ≈0.14 in both planes. This paper investigates the SC-driven beam dynamics in the REC, the resulting emittance growth, and potential beam loss.
Paper: THP5328
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5328
About: Received: 12 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP5329
Dynamic aperture optimization for the Ring-based Electron Cooler
4232
Electron Ion Collider (EIC) will benefit from cooling protons at the highest collision energy (γ=294). The required cooling can be provided by the Ring Electron Cooler (REC) - an RF-based non-magnetized electron cooler employing an electron storage ring. As stored electrons cool the EIC protons, their emittance is gradually increased by both the intra-beam and beam-beam scattering. To counteract the heating of electron bunches, eighteen dedicated damping wigglers are utilized. These wigglers require substantially non-linear field with peak value of 2.4 T, occupy a large portion of the electron storage ring, and dominate beam dynamics in the REC. In this paper we describe our approach to maximizing dynamic aperture in the REC, which includes careful optimization of wigglers parameters and development of an elaborate correction scheme for non-linear beam dynamics.
Paper: THP5329
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5329
About: Received: 12 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP5335
Magnetic field reconstruction from sparse measurements for complex geometries
4239
Precise 3D field measurements of large, complex magnet geometries are time-consuming and error-susceptible. For large magnets, it is common to record Hall probe data on a sparse grid, then use an interpolation algorithm to estimate field values at the remaining points. For common magnet geometries, such as quadrupoles and dipoles, linear interpolation often provides accurate results. However, for complex magnet geometries, this method can yield lower accuracy. In this paper, we present a method based on a locally Maxwell-consistent algorithm for sparse Hall probe measurements. Through the k-nearest neighbors algorithm, we locally fit the magnetic field with Tikhonov regularization. We test this method on a novel Compton spectrometer, capable of measuring single-shot, double-differential, energy-angle gamma spectra, ranging from 180 keV to 28 MeV. Using held-out validation, we demonstrate that we can reconstruct its magnetic fields with higher accuracy than linear interpolation and radial basis function (RBF) interpolation with cubic, thin plate spline, and quintic kernels. We also analyze the dependence of point sparsity on accuracy.
Paper: THP5335
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5335
About: Received: 14 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP5337
LCLS-II Gun FPC window MP analysis
4243
The RF analysis of the LCLS-II Gun fundamental power coupler (FPC), including the ceramic window, has been analyzed using SLAC-developed 3D parallel finite-element electromagnetic code suite, ACE3P. Comprehensive multipacting (MP) simulations were carried out to investigate potential discharge regions within the FPC coaxial line and window assembly. The results reveal strong two-point MP between the ceramic disk and the window shielding sleeve at specific input power levels. In addition, the studies show that the external magnets mounted on the two FPC arms can only provide localized suppression of MP within regions influenced by their fringe magnetic fields. Therefore, effective MP mitigation in the LCLS-II FPC relies primarily on TiN coatings applied to the coaxial copper surfaces and ceramic disk, which reduce their secondary electron yield (SEY) below unity. Detailed analysis and findings from the LCLS-II Gun FPC RF simulations are presented.
Paper: THP5337
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5337
About: Received: 12 May 2026 — Revised: 20 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
THP5360
A Flat-Pulse Analytic Framework for Modeling Inverse Compton Scattering and Ponderomotive Broadening
4266
We present a new general analytic formula for radiation spectra of inverse Compton scattering due to a flat laser pulse at any scattering angle. Using the analytic solution for a flat laser pulse, we build an approximation of a Gaussian pulse as a series of flat pulses with varying field strengths. From this description we obtain an expression for the phase modulation between successive flat pulses due to changing field strength, which leads to ponderomotive broadening in the scattered spectra.
Paper: THP5360
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5360
About: Received: 18 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP5602
Analysis and research on measurement errors caused by Magnet misalignment in energy analysis systems
4281
Accurate evaluation of the beam energy and energy spread plays a crucial role in the commissioning and operation of electron accelerators. The energy analysis (EA) system, consisting of a dipole with associated upstream and downstream drift sections, is widely applied in accelerator facilities due to its structural simplicity, large measurement range, and high resolution. However, assembly errors, leading to offsets or tilt angles between the input beam and the designed system axis, are inevitably introduced during engineering implementation. Such misalignment necessarily affect the accuracy of the measurement results of the EA system, and the impact may be even more significant for low-energy e-beams with the energy of a few MeV. In this context, based on the low-energy injector experimental platform currently under construction, the misalignment induced errors in the dipole-based EA systems are analyzed in depth, and potential compensation methods are explored. The study aims to provide both theoretical support and practical guidance for optimizing system alignment and improving measurement precision.
Paper: THP5602
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5602
About: Received: 11 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP5611
Lattice design to achieve reversible microbunching in a steady-state microbunching (SSMB) storage ring
4297
Steady-state microbunching (SSMB) has been proposed as a new light source mechanism to generate high average power coherent radiation in electron storage rings. One approach to achieving SSMB is the reversible microbunching scheme, which introduces a laser-based energy modulation to electron bunches in a localized insertion section to form microbunching, and then uses a subsequent energy demodulation to remove the microbunching and restore the bunches to their nominal state in the storage ring. In this paper, we report a modulation–demodulation lattice design for an SSMB storage ring based on the reversible microbunching approach. By self-consistently accounting for non-ideal effects such as intrabeam scattering (IBS) and higher-order nonlinearities, sub-nanometer longitudinal position deviations of the electrons between the laser modulators can be achieved, ensuring precise cancellation of the energy modulation and maintaining the electron bunches in a steady state, thereby ensuring high average radiation power.
Paper: THP5611
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5611
About: Received: 04 May 2026 — Revised: 07 May 2026 — Accepted: 14 May 2026 — Issue date: 22 May 2026
THP5627
Symplectic integration for storage ring based FEL in Genesis
4330
Symplectic integration is essential for simulating the long-term stability of systems such as storage rings. In contrast, it has traditionally been considered unnecessary for single-pass free-electron laser (FEL) simulations. Consequently, standard FEL simulation codes, like Genesis, have not fully incorporated symplectic methods in their treatment of the beam dynamics. However, with the growing interest in storage ring-based FELs, the requirement for symplectic tracking in the FEL dynamics process has emerged. This paper presents a modification of the Genesis code to implement a symplectic algorithm for its dynamical part. A comparative analysis between the symplectic and non-symplectic approaches is conducted. The results demonstrate that the symplectic Genesis preserves the symplecticity of beam dynamics without compromising the accuracy of the radiation simulation, thereby providing a more reliable tool for accurate storage ring FEL modeling.
Paper: THP5627
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5627
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 19 May 2026 — Issue date: 22 May 2026
THP5638
Experimental design for validating relativistic ponderomotive dynamics via laser modulation of MeV electron beams
4349
We present a design for the experimental validation of relativistic ponderomotive dynamics on a realistic MeV electron-beam platform. The scheme combines an S-band gun with a co-propagating focused laser pulse to induce longitudinal momentum modulation in relativistic electrons. Using a nonparaxial laser-field model and beam-dynamics simulations, we evaluate the expected post-interaction energy signatures and their observability on a practical beamline. Particular attention is given to the dependence of the modulation on laser focusing, beam parameters, and synchronization errors. The analysis identifies the dominant force contributions governing the final energy distribution. These results provide a practical route for translating previously derived relativistic ponderomotive theory into a testable experiment.
Paper: THP5638
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5638
About: Received: 15 Apr 2026 — Revised: 06 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
THP5642
Impedance studies on the electrostatic separators
4357
Electrostatic separator is a crucial component required in the Circular Electron Position Collider to separate electron and positron beams, therefore the two beams can share the RF cavities at high beam operation energies. The impedance contribution from the component is one of the main concerns during the design of the structure. In this paper, the impedance characteristic of the electrostatic separator is investigated. The transverse higher order modes trapped in the component is examined in both simulations and laboratory bench measurements. The mitigation of the trapped modes is also explored.
Paper: THP5642
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5642
About: Received: 14 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP5652
Impact of initial energy spread on the accuracy of energy spread growth formula in a free electron laser
4372
Evaluating the energy spread growth due to radiation is crucial for the design of steady-state microbunching (SSMB) insertion section. This study systematically benchmarks a classical analytical formula against three-dimensional numerical simulations to validate its accuracy under varying initial energy spreads. Our findings reveal that while the formula provides reliable estimations for beams with small initial energy spreads, its predictions deviate significantly as the initial energy spread increases. Such discrepancies arise because larger initial energy spreads amplify three-dimensional effects and nonlinear beam dynamics, which compromise the idealized analytical model. This study shows that comprehensive 3D simulations are indispensable for robust and accurate SSMB insertion section design.
Paper: THP5652
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5652
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP5653
The impact of transverse-longitudinal coupling on longitudinal microwave instability
4374
In a storage ring with an extremely small global phase slippage, the bunch length can vary significantly within one turn due to the partial phase slippage and transverse-longitudinal coupling, which means the adiabatic approximation usually adopted for longitudinal dynamics breaks down. The impact of such a bunch length variation and exchange of the head and tail part of the beam arising from the partial phase slippage on the coherent synchrotron radiation (CSR) induced longitudinal microwave instability (MWI) threshold has recently been theoretically investigated by some of the authors*. In this work, we have extended the study to consider the influence of transverse-longitudinal coupling.
Paper: THP5653
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5653
About: Received: 13 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
THP5662
Time-of-flight control and passive compression in an Alpha-magnet beamline for MHz MeV UED
4386
We propose a novel MeV UED beamline design based on a normal-conducting very-high-frequency (VHF) electron gun that generates a high-quality electron beam at a megahertz (MHz) repetition rate. Beam compression and time-of-flight (TOF) control are achieved using an alpha-magnet. Simulations show compression of the 4.1 fC electron beam to a duration of 4.7 fs RMS, with a TOF jitter of 1.9 fs RMS, alongside normalized transverse emittances of 5.6 nm·rad in the x-direction and 5.2 nm·rad in the y-direction. This design substantially enhances both the signal-to-noise ratio and temporal resolution of the UED beamline, establishing a robust foundation for the future development of UED facilities.
Paper: THP5662
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5662
About: Received: 06 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
THP5677
Preliminary analysis of transient beam-loading effects in electron storage rings with a 3rd harmonic cavity
4412
In a 4th generation electron storage ring, harmonic cavities are often employed for increasing bunch length and beam lifetime. Effective bunch lengthening can be achieved when the first derivative of total accelerating voltage is near zero. However, the accelerating voltage fluctuation due to transient beam-loading (TBL) effect can affect the bunch lengthening in the harmonic cavity system. Therefore, we utilize both a Haissinski equation solver and a macroparticle tracking code to predict equilibrium beam distribution under TBL effects. The equilibrium longitudinal beam distributions obtained from both approaches are presented and cross-validated for different fill patterns.
Paper: THP5677
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5677
About: Received: 07 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THV5602
Universal representation of chromatic aberration in electron beam optics
4437
We present a novel unified approach to the expression and correction of electron beam chromatic aberrations, which comprehensively covers optical systems of both a single-pass beam transport line and a circular accelerator satisfying periodic boundary conditions. In an electron circular accelerator, linear chromaticity has been utilized to express the first-order difference in beam focusing caused by the electron energy deviation, which can be computed by a well-known formula using a beam envelope function (Twiss parameters). However, this conventional formulation is incompatible with non-periodic beam transport lines, such as XFELs driven by linacs and the final focus system of linear colliders. We address this discrepancy by deriving a generalized formula that seamlessly connects the two different accelerator topologies. Our representation not only reproduces the well-known ring chromaticity but also provides a consistent and practical definition of chromatic aberrations for a single-pass transport line and their correction methods. This presentation outlines one approach to resolving this apparent contradiction and the universal formula to express chromatic effects.
Paper: THV5602
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THV5602
About: Received: 12 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026