proton
MOO1T03
Progress towards a muon collider
34
The muon collider concept promises a unique opportunity to push the energy frontier in particle physics. The large muon mass suppresses synchrotron radiation and allows the acceleration and collision of the beams in rings and the use of technology more similar to hadron colliders. Muons are point-like, in contrast to protons, and thus can achieve a similar physics reach with less energy, allowing for a more compact machine. However muons have a lifetime of only 2.2 microseconds at rest. The muon beam thus needs to be cooled and accelerated rapidly to maximise the luminosity, which creates several technology challenges. The International Muon Collider Collaboration is implementing an intense R&D programme to address these challenges and to develop the concept maturity. The presentation will highlight the key challenges, summarise the progress of the work and the proposed R&D plan for the next decade.
Paper: MOO1T03
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOO1T03
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
MOP1001
Study of quench margins for betatron Halo losses with new HL-LHC collimation optics
64
The High-Luminosity Large Hadron Collider (HL-LHC) will mark a new phase of LHC operation, aiming to reach an integrated luminosity of 3000 fb$^{-1}$ over 10 years of operation. A key element to achieve the target luminosity is the beam intensity increase, nearly doubling the number of protons per bunch compared to the initial LHC design. This increases the load on the collimators protecting against beam losses, particularly in the betatron cleaning insertion region (IR7), a multistage collimation system responsible for beam halo cleaning. Particles intercepted here may undergo diffractive scattering and propagate for hundreds of meters, reaching the adjacent dispersion suppressor (DS) sections. To assess the impact of these losses, FLUKA simulations have been performed to predict the power deposition in the superconducting DS magnets on both sides of IR7. Accurate modelling of these losses is essential to ensure safe machine operation and to optimize beam loss monitor thresholds, minimizing unnecessary protective beam dumps. In this contribution, we present shower simulation studies for the latest HL-LHC collimation optics (v1.6), with improved cleaning and impedance in IR7, and compare them to the previous one (v1.5).
Paper: MOP1001
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1001
About: Received: 13 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
MOP1029
Studies of crystal and amorphous collimation of lead, oxygen and neon beams at LHC
116
The Large Hadron Collider (LHC) at CERN operates with lead-ion beams for about one month each year, requiring a high-performance collimation system to protect the machine from beam losses. The baseline ion-collimation scheme includes crystal collimation. In 2025, additional ion runs were carried out using oxygen and neon beams, enabling the first experimental comparison of collimation performance between crystal-based and standard systems for these lighter ions. This work presents a comparative review of measured and simulated collimation performance for lead, oxygen, and neon ions at the LHC using both standard and crystal collimation techniques. The results offer a valuable benchmark for simulation tools used to predict collimation efficiency and provide key input for future LHC ion runs, where ion species other than lead are being considered.
Paper: MOP1029
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1029
About: Received: 12 May 2026 — Revised: 14 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
MOP1030
Monte Carlo studies of muon background at SND@LHC
120
The dominant background at the SND@LHC experiment consists of muons reaching the detector after traversing several tens of meters of rock. Monte Carlo simulations were instrumental in the experiment design and the background study. For the latter, a two-step workflow was adopted, first simulating with FLUKA proton$-$proton collisions in ATLAS and recording secondary muons on a virtual interface plane in the rock, and then propagating them to SND@LHC with Geant4. Benchmarking of simulated integral fluxes against Run-3 measurements showed a level of agreement within 10$-$30$\%$ and enabled the interpretation of the significant variations that were observed as a function of the LHC optics and beam crossing plane. In particular, the role of diffractive proton losses in an accelerator cell upstream of the detector was highlighted. On this basis, effective mitigation strategies, such as orbit bumps displacing these losses to other cells, were explored. For the HL-LHC configuration of Run-4, first estimates indicate a significantly higher muon background than in Run-3, reflecting not only the planned luminosity increase but also the larger leakage due to the magnet aperture enlargement.
Paper: MOP1030
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1030
About: Received: 13 May 2026 — Revised: 15 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
MOP1095
ESSnuSB+: target station studies
277
The ESSnuSB+ project aims to produce an intense neutrino beam using the high-power proton linac of the European Spallation Source (ESS). A key element of the facility is the target station, where a 2.5 GeV proton beam interacts with a granular titanium-sphere target to generate an intense pion-meson beam. These pions are focused by a magnetic horn and directed toward a storage ring before decaying into the muons that will be stored in the ring while emitting the neutrinos. In this work, detailed FLUKA simulations are used to model the full chain of particle production and energy deposition across major components of the target station. The simulations quantify the spatial distribution of deposited power and radiation dose. These results are essential for validating the feasibility of the target design, assessing component lifetime, and informing the engineering of cooling and shielding systems. Furthermore, updated predictions of the pion production are presented, representing the first step in the optimisation of the neutrino production for the ESSnuSB+ experiment. These results contribute to the overall design validation of the facility.
Paper: MOP1095
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1095
About: Received: 07 May 2026 — Revised: 10 May 2026 — Accepted: 14 May 2026 — Issue date: 22 May 2026
MOP1098
LEnuSTORM: A low-energy muon storage ring for neutrino cross-section measurements
280
The LEnuSTORM (low-energy neutrinos from stored muons) is a proposed facility that enhances the performance of the ESSnuSB* (European Spallation Source Neutrino Super Beam) project by measuring neutrino cross sections in the energy range 200-600\,MeV, where data is largely missing. The facility utilizes a 1.25\,MW proton beam from the European Spallation Source linac, which is compressed in an accumulator into 1.2\,µs pulses and directed at a granular titanium target embedded in a horn. Pions collected by the horn are transferred and injected into a racetrack-shaped storage ring where they decay and emit muons that will be stored in the ring for a few tens of turns. The neutrinos emitted in the muon decay in one of the straight sections will travel to a water Cherenkov detector, where the interactions are monitored. At LEnuSTORM, the beam is large and very divergent, and thus difficult to contain. The ring design presented in this paper uses iron-dominated magnets to reduce complexity, and a compact FODO lattice with strong focusing to maximize neutrino production by allowing a large transverse acceptance. However, the design pushes fringe-field effects beyond the linear regime and requires a paraxial expansion with higher-order terms, introducing resonances and reduced dynamic aperture. We present here a design that aims at balancing the transverse and momentum acceptance with the dynamic aperture, to maximise neutrino production.
Paper: MOP1098
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1098
About: Received: 11 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP1105
Refined design of the front-end complex for a Muon Cooling Demonstrator at CERN
292
The muon collider has great potential for enabling high-luminosity multi-TeV lepton– antilepton collisions provided low-emittance, high-intensity muon beams can be produced. Ionization cooling is the proposed technique to achieve the required muon beam emittance. The International Muon Collider Collaboration aims to demonstrate the integration and reliable operation of a 6D ionization cooling system, including RF acceleration in strong magnetic fields. This study advances the design of the muon production and transport systems for a Muon Cooling Demonstrator implemented in the CERN CTF3 building. Building on previous work, the design is extended to finalise the beam-preparation section and the matching of the transport line into the cooling channel. The target–horn model has been further optimised and now incorporates a forced- convection helium cooling system, providing a more mature and realistic representation. An extended FLUKA model of the target area is used to assess and optimise shielding requirements.
Paper: MOP1105
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1105
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
MOP1109
First observation of controlled beam-halo population and cleaning at the LHC by an AC dipole
304
Experimental observations indicate that a significant fraction of the stored beam energy in the CERN Large Hadron Collider (LHC) is contained in the transverse beam halo. Combined with the anticipated increase in beam brightness in the High-Luminosity LHC (HL-LHC) and new expected fast failure scenarios resulting in a loss of large-amplitude particles, an overpopulated beam halo poses risk to the safe operation of the machine. Following removal from the HL-LHC baseline of the Hollow Electron Lens, which was studied as the preferred method for active halo control, alternative halo-cleaning methods need to be investigated. A novel method being explored is the use of an AC multipole operated in resonance with the betatron tune to create a stable island in phase space in which halo particles are adiabatically trapped and transported to the collimators in a controlled manner. This paper presents the results of the first successful proof-of-principle measurement of both controlled beam-halo population and cleaning using an AC dipole at the LHC.
Paper: MOP1109
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1109
About: Received: 17 Apr 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
MOP1116
Design and manufacturing of the next generation of CERN’s North Area Splitter Collimators (TCSC)
319
CERN’s Transfer Tunnel 20 (TT20) connects the Super Proton Synchrotron (SPS) to three primary targets in the North Area which provide secondary particles to experiments further downstream. Two splitter collimators (TCSC) are installed along this line, each protecting their respective downstream Lambertson septum magnets, which distribute the slow-extracted 400 GeV/c proton beams among the targets. During Long Shutdown 3 (LS3, 2026–2029), two redesigned TCSCs will be installed to improve cooling efficiency, mechanical robustness, and maintainability in the context of the North Area Consolidation (NA CONS) project. The new design also incorporates additional radiation shielding to reduce dose rates in the surrounding area and minimise personnel exposure during tunnel interventions. This contribution presents the main design improvements, thermo-mechanical analyses, and manufacturing developments implemented to enhance the reliability, radiation safety, and thermal performance of the TT20 splitter collimators.
Paper: MOP1116
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP1116
About: Received: 08 May 2026 — Revised: 19 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
MOP6001
Eliminating mains noise effects in accelerators with Machine Learning
341
Power supply ripples at various frequencies - characteristic to the magnet circuits or from the electrical network - have always been an issue in accelerator operations, with several mitigation measures put in place over the years. This contribution summarises the efforts in the CERN SPS over the last years to compensate the ripple at 50 Hz and its harmonics in the main quadrupole circuits, using Machine Learning methods. The detrimental effects of the ripple at low energy for LHC-type beams and at top energy for slow extracted beams are introduced. For optimal conditions of slow extracted beams, a continuous control algorithm had to be conceived. The implementation required hardware modifications on the power converter electronics side, additional new controls infrastructure and the development of adaptive algorithms that can deal with changes in the electrical distribution network throughout the day. Continuous control with tailored adaptive Bayesian Optimisation has been implemented for slow extracted spill control throughout 2024 and 2025. The improved spill quality obtained over the years will be discussed. Finally, results from R&D towards one-shot correction algorithms for beams that are only played on-demand (i.e. LHC beams) will also be briefly summarised.
Paper: MOP6001
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6001
About: Received: 11 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
MOP6357
Design of ionization profile monitors at the Integrable Optics Test Accelerator (IOTA) Facility at Fermilab
415
The Integrable Optics Test Accelerator (IOTA) at Fermilab is transitioning from an electron beam facility to a proton beam facility for studies in nonlinear accelerator optics and space-charge dominated proton beams. This project involves the commissioning and fabrication of Ionization Profile Monitors (IPMs) to enable beam profile measurements at IOTA. In general, IPMs work on principle of residual gas ionization by the beam to generate beam profile. This work focuses on a mechanical design that leverages a controlled injection of noble gases, primarily Argon, as the ultra-high vacuum of the IOTA ring provides insufficient residual gas for ionization. Efforts to understand vacuum integration to ensure compatibility with the storage ring environment, the integration of real-time data acquisition systems and the commissioning of the IPMs will be discussed. This project provides a versatile diagnostic tool, supporting IOTA’s role as a testbed for larger-scale accelerator facilities and contributing to the broader understanding of beam physics in high-intensity, high-space-charge regimes.
Paper: MOP6357
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6357
About: Received: 19 May 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
MOP6370
Diagnosing ghost bunches with the upstream extinction monitor in the Mu2e experiment
419
The Mu2e experiment has a stringent requirement for extinction of the pulsed proton beam, referring to the elimination of particles between proton bunches to a relative level of $10^{-10}$, which means a single out-of-time particle in the inter-pulse gaps for every 250 complete proton pulses. As the construction of the Mu2e experiment nears completion, it is crucially important to make an early measurement of the beam extinction in its current condition. Hence the upstream extinction monitor was constructed and operated to probe for problems in the proton pulse structure or a higher than expected incidence rate of out-of-time particles. The analysis in this work comes from data taken in March 2026. The long data run showed a significant presence of out-of-time particles from ghost bunches in the Delivery Ring approximately 388 ns after the centers of the main proton pulses. These are hypothesized to be the result of a combination of a RF frequency mismatch, particle space charge, and machine impedance during the rebunching sequence in the Recycler Ring, which can lead to particles leaking into adjacent buckets, but further studies and simulations are needed to confirm this.
Paper: MOP6370
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6370
About: Received: 14 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
MOP6614
The development of novel beam diagnostics for low-MeV protons
489
In charged particle therapy, high energy layer switching times prolong beam delivery time, limiting treatment efficiency and accuracy. The TURBO (Technology for Ultra-Rapid Beam Operation) project aims to build a low-energy (0.5-3 MeV) demonstrator beamline for proton therapy with a large momentum acceptance (±42%), enabling rapid delivery over the full clinical energy range, alleviating this bottleneck. Novel beam diagnostic instrumentation is required to monitor key parameters of the beamline constructed for the University of Melbourne’s Pelletron accelerator, which operates at low energies and high current densities. We develop a pepper-pot mask-based method to measure beam phase space distribution and quantify the emittance, and a multi-layer Faraday cup (MLFC) to measure energy distribution. This work now enables the completion of the beam shaping section, and integration of a fixed-field, closed-dispersion beam transport section, key next steps toward assessing TURBO’s potential to shorten beam delivery times.
Paper: MOP6614
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP6614
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
MOP7019
Optimized low-cost, high-efficiency cavity design for 100–500 MeV proton linacs
677
Over the past four decades, the accelerator community has made substantial progress in advancing both normal-conducting and superconducting RF cavity design and fabrication technologies. As the global demand for new accelerator facilities continues to increase, the development of low-cost, high-efficiency RF cavities has become essential for ensuring the long-term sustainability of accelerator science. In this work, we introduce a new RF cavity concept, designated Alansa-PL, developed by the ISIS Linac Group. This design provides a simpler and more efficient alternative to conventional coupled-cavity structures. Preliminary studies indicate that the Alansa-PL cavity exhibits enhanced performance for proton accelerators in the 100–500 MeV energy range. The conceptual design and electromagnetic modelling of the cavity, operating at 972 MHz with β = 0.5, are presented and discussed in this paper.
Paper: MOP7019
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7019
About: Received: 15 Apr 2026 — Revised: 21 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
MOP7070
Static and dynamic field characterisation of the super proton synchrotron bending magnets
794
To ensure precise control of field quality in normal-conducting accelerator magnets, it is essential to develop models that accurately represent magnetic hysteresis during operational cycles. This study focuses on the dipole magnets of the CERN Super Proton Synchrotron (SPS) and investigates how variations in operational cycles produce different hysteresis and dynamic patterns in the integrated main magnetic and higher-order field multipoles. A combination of various magnetic field measurement systems was employed to evaluate the magnetic field quality, enabling direct observation of history dependence and reproducibility. Three regimes are identified: a history-dependent reversal curve along the ramp, eddy-current settling during end-of-ramp transients, and a rate-independent transfer function at the plateau. The analysis covers the integrated dipole and sextupole components, distinguishing rate-dependent eddy current effects from quasi-static hysteretic contributions. Two pre-cycle patterns currently used in operation are compared: a \SI{200}{GeV} cycle and a \SI{26}{GeV} cycle introduced in 2026 within the CERN Efficient Particle Accelerator (EPA) initiative. The aim is to provide a quantitative single-magnet assessment of this change of operation.
Paper: MOP7070
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7070
About: Received: 11 May 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP7098
The beam stops for the ESS superconducting linac
851
For the ESS superconducting linac in Sweden, four compact beam stops were designed instead of bulky beam dumps. The beam stops dump protons either up to 100 MeV or 250 MeV; the most demanding beam modes have an average beam power of 700 or 1100 W, respectively. The beam stops are water-cooled and moved by pneumatic actuators. The beam stops were designed at the ESS in Sweden and manufactured by Proactive R&D in Spain. The assembly, acceptance tests and metrology measurements were performed in ISO-5 cleanrooms, before the installations in the particle-free environment next to superconducting cavities of the ESS linac. This contribution summarizes the assembly, testing and operational experience.
Paper: MOP7098
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7098
About: Received: 11 May 2026 — Revised: 17 May 2026 — Accepted: 17 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
MOP7107
SMAUG experiments at CERN’s HiRadMat facility for the study of materials used for particle beam windows
877
The series of SMAUG experiments performed at the HiRadMat facility within the CERN accelerator complex investigated the performance limits of materials suitable for particle beam windows under extreme proton beam conditions. Materials including; Glassy Carbon, Beryllium (grades I-220-H, S-200-FH, PF-60®), and Silicon Nitride (Si₃N₄) were exposed to 440 GeV/c proton beams with total intensities up to 2.8x10^15 protons and beam spot sizes ranging from σ 0.5mm to 0.25mm. Multiple configurations (SMAUG 1, 1.5, and 2) simulated high intensity operational conditions, also replicated previous failures observed in TT66 Be windows. Post-irradiation analysis included leak detection, optical microscopy, SEM, and 3D topology measurements, combined with FLUKA beam energy simulations to demonstrate material performance.
Paper: MOP7107
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7107
About: Received: 12 May 2026 — Revised: 15 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
MOP7135
Design and Development of the New ISOLDE Beam Dumps at CERN
943
New beam dumps have been developed for the Isotope mass Separator On-Line facility (ISOLDE) at CERN, as part of the ISOLDE Beam Dump Replacement and Sustainability (IBDRS) project. The new design is engineered to ensure an operational lifetime of 30 years and, as by-product, to accommodate the planned doubling of beam power. The absorber assembly consists of water-cooled slices of cladded CuCr1Zr and pure copper. The cladding consists of an encapsulation of 316LN stainless steel, diffusion bonded to the cuprous core by means of Hot Isostatic Pressing (HIP). The cladded blocks are enclosed within a 316 LN stainless steel vessel, which allows the use of pressurised water to cool the dump. Extensive Monte Carlo and thermo-mechanical studies were conducted to evaluate temperature and stress distribution under nominal and accidental beam conditions, as well as the fatigue lifetime and cooling requirements. Prototyping of the cladded blocks have been produced successfully. This contribution presents the conceptual design, which employs advanced manufacturing methods to provide a sustainable and robust solution for the future ISOLDE beam dumps.
Paper: MOP7135
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7135
About: Received: 12 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
MOP7136
Upgrade of the SPS Target External Dump for high intensity operation in CERN’s North Area
947
As part of the consolidation of CERN’s North Experi-mental Area (NA-CONS project), a dump located in the TT20 transfer line has been redesigned to comply with the higher beam intensities required for the future BDF/SHiP facility, and to improve its operational relia-bility. The new dump must be capable of dissipating up to 45 kW of steady-state power generated by the slow extraction of 400 GeV/c protons from the SPS under vari-ous operational scenarios. In addition, it shall also be able to withstand short, high-intensity pulses during machine development phases. Building upon proven design concepts implemented in the previous generation of SPS dumps [1,2], the dump core consists of graphite blocks clamped by actively cooled CuCr1Zr plates, and is enclosed by two shielding layers, steel and marble, for radiological protection. The design has been validated by performing beam-matter and thermo-mechanical simu-lations. A dedicated testbench was used to estimate the thermal contact conductance between materials and pro-vide realistic values for the simulations. This contribu-tion presents the main stages of this upgrade, from defini-tion of updated beam parameters to conceptual design and validation.
Paper: MOP7136
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7136
About: Received: 23 Apr 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
MOP7137
Conceptual comparison of liquid lead flow configurations for a muon collider
951
Liquid lead is under investigation at CERN as a candidate material for a multi MW-Class production target for a future Muon Collider. A free-surface curtain was initially proposed to decouple structural walls from beam-driven shock waves resulting from the high instantaneous energy deposition on the target material. However, later studies revealed that the large vertical extent required for this configuration limits the particle production efficiency, which motivated the development of a jet concept proposed in this work. Because the target operates within a 20 T solenoidal magnetic field, magnetohydrodynamic (MHD) effects are expected to influence the liquid-metal flow. Estimates indicate operation at low magnetic Reynolds numbers, where electromagnetic induction is weak. Nevertheless, the strong applied magnetic field leads to significant Lorentz forces that can affect flow stability and hydraulic performance. Both configurations are analysed using coupled multiphase computational fluid dynamics-magnetohydrodynamics (CFD-MHD) simulations in the quasi-static approximation to investigate current distribution, magneto-hydrodynamic damping, and free-surface deformation. The comparison highlights the main physical trade-offs between the two concepts and defines the framework for ongoing design optimisation.
Paper: MOP7137
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP7137
About: Received: 11 May 2026 — Revised: 18 May 2026 — Accepted: 21 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
MOP8615
A computational methodology for the efficient AC-225 production via proton irradiation of RA-226
1153
Ac-225 is a crucial isotope for targeted alpha therapy, yet its clinical application is severely constrained by supply shortages. The use of high-intensity proton beams to irradiate Ra-226 targets offers a viable approach to significantly enhance Ac-225 production, as it enables higher yields and greater scalability. However, the process is also accompanied by the generation of other isotopes of actinium, especially the long-lived Ac-227, which challenges the purification process. This work establishes a precise parameterized model that correlates beam energy, target thickness, and cooling time with each other for optimizing Ac-225 production while minimizing Ac-227 impurity levels and target material consumption. We determine the optimal parameters, which effectively maximize Ac-225 yield while controlling impurity levels and target material consumption. This method provides a valuable reference for the efficient production of Ac-225
Paper: MOP8615
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOP8615
About: Received: 11 May 2026 — Revised: 16 May 2026 — Issue date: 22 May 2026
MOV7005
Experimental study of beam-induced damage in Nb₃Sn sample coils pre-irradiated up to 30 MGy
1194
Superconducting magnets of high-energy accelerators are vulnerable to beam-induced damage and previous experiments have characterized the damage limits of Nb$_3$Sn sample coils under proton-beam impact. This paper presents a follow-up experiment at CERN's HiRadMat facility investigating the combined effect of radiation ageing and beam impact on superconducting sample coils. The coils were pre-irradiated to simulate the integral dose anticipated for the final-focusing triplet quadrupole magnets of the High Luminosity LHC (HL-LHC) at the end of their lifetime. Following a review of the experimental motivation and preparation of the samples, the final experimental setup is described, including sample positioning and expected temperature profiles under beam impact. Metrology measurements, survey operations, and beam-based alignment, used to ensure adequate beam impact parameters, are detailed together with the proton beam parameters used to irradiate the samples. FLUKA simulations constrained by measured beam size, intensity, and position provide estimates for the local temperature rises and gradients. The timeline of the successfully completed experiment is reviewed. The ongoing post-irradiation analysis, including the assessment of beam-spot characteristics using radiation-sensitive film and the critical-current measurement campaign, is discussed in detail.
Paper: MOV7005
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-MOV7005
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 22 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
TUP3009
Beamline optimization for Laser-Accelerated Ions
1562
Laser-plasma acceleration can generate short, intense ion beams with energies up to several hundred MeV. However, the intrinsic large divergence and broad energy spectrum of these beams necessitate dedicated capture and transport beamlines to achieve high particle yields for applications. In this work, we use the LIGHT beamline with the PHELIX laser at GSI as an example case to develop and evaluate methods for optimizing and aligning such beamlines. Our focus is on future applications including injection into conventional accelerators and as a complement to traditional ion sources. Using the UNILAC at GSI as a reference case, we show that, for the present PHELIX laser intensities the number of laser-accelerated protons viable for SIS18 injection remains at least an order of magnitude below the typical bunch intensity of conventional linacs. Finally, by deriving and applying scaling laws for the transmission through the first capture element, we propose strategies for further improvement to bridge this gap in the future.
Paper: TUP3009
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3009
About: Received: 13 May 2026 — Revised: 18 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
TUP3035
Nonlinear transverse beam dynamics in AWAKE Run 2c
1600
The AWAKE experiment harnesses the 400 GeV proton beam from the CERN SPS to drive plasma wakefields, which in turn accelerate a witness bunch of electrons to high energy. Upgrades are currently being carried out to facilitate the experimental programme of Run 2c, which includes control of the witness bunch quality during acceleration. We here present the first full simulations of the beam–plasma interaction for AWAKE Run 2c, including self-modulation of the proton drive beam and the acceleration of the witness bunch in the wakefields of the resulting train of driver microbunches. We demonstrate that the length of the proton drive beam has a significant impact on the transverse wakefield dynamics which impact the quality of the accelerated electron witness. These simulations inform the choice of parameters for the experiment.
Paper: TUP3035
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP3035
About: Received: 12 May 2026 — Revised: 20 May 2026 — Accepted: 21 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
TUP8007
Commisioning of a new beamline for medical research and radiation hardness testing
2046
The HZB cyclotron accelerator complex provides 68 MeV protons for therapy and related research. The main accelerator is an isochronous sector cyclotron served by two injectors. The treatment room is fixed according to the regulatory agencies and the adjoining experimental station is often overbooked with users for radiation hardness test and dosimetry. To widen the irradiation possibilities, we built up a new beamline for medical research with minibeams and a second target station is prepared for radiation hardness experiments. The setup, possibilities and commissioning for these stations will be presented.
Paper: TUP8007
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUP8007
About: Received: 07 May 2026 — Revised: 16 May 2026 — Accepted: 17 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
TUV8001
Commercial Accelerators for Proton Therapy - An Overview
2121
There are different accelerator types used for proton therapy of diverse tumours. In use are mostly classical cyclotrons, synchrocyclotrons and synchrotrons. In addition, linear accelerators were or are under development. This paper will give an overview on commercially available systems. Not only technical aspects are discussed, but also new developments in treatment methods like ARC and FLASH therapy as well as irradiations in upright position and the backlash on the used accelerator types. Furthermore practical issues like certification and embedding those systems in a hospital environment will be described and evaluated.
Paper: TUV8001
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUV8001
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
WEO4M02
Beam tests of a permanent magnet medical accelerator arc from 10-250MeV
2148
The FLASH hadron therapy accelerator proposed by Trbojevic uses permanent magnets with nonlinear fields to allow rapid cycling from 10 to 250MeV while keeping the ring tune constant. A test beamline of four cells from this ring (22.5 degree angle) was built at BNL and tested at the NSRL facility with protons and at the Tandem Van de Graaff with deuterons. The magnets consist of 24 neodymium-iron-boron (NdFeB) wedges magnetised in different directions and arranged to produce the required nonlinear field profile across the oval aperture for the beam movement, with fields of up to 1.85 Tesla. Beams were transmitted at all rigidities tested over a 5.3x momentum ratio, with output location moving systematically with energy as required.
Paper: WEO4M02
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEO4M02
About: Received: 14 Apr 2026 — Revised: 12 May 2026 — Accepted: 15 May 2026 — Issue date: 22 May 2026
WEP1012
FLUKA studies of spent beam extraction in the muon collider target system
2223
A multi-TeV muon collider relies on a particle souce based on a megawatt-scale proton beam striking a target to produce muons and pions immersed in a 20 T solenoid, followed by a tapering region and a chicane in solenoid magnets to capture and guide the pions and then muons toward cooling sections. For the characteristic target lengths that maximise the pion yield, a fraction of the proton beam is expected to exit the target without inelastic collisions. These protons carry high power in a highly collimated phase space, requiring a dedicated extraction scheme downstream of the target. Within the International Muon Collider Collaboration, simulations have been performed with the FLUKA Monte Carlo code to evaluate potential extraction strategies in both the target region and the downstream chicane. These studies assess power deposition, dose, and atomic displacements in the target and downstream areas and analyse shielding options to protect sensitive elements. The work defines the main radiation-driven design constraints and compares the main benefits and shortcomings of each option.
Paper: WEP1012
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1012
About: Received: 13 May 2026 — Revised: 21 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
WEP1301
RHIC Au-Au Operation at 100 GeV in Run 25
2239
The Relativistic Heavy Ion Collider (RHIC) Run 25 operations consisted of collisions of 100 GeV/u Au beams and a short 100 GeV polarized proton run for the STAR and sPHENIX experiments. A magnet wiring short resulting from the Run 23 failure repair resulted in a 2 month delay to the start of the run. Machine optimizations produced the highest ion performance in the history of the complex but the run was interrupted by a pair of two-week failure periods. This paper will discuss the progress made by each experiment and the failures and successes of the final year of the operation of the RHIC accelerators.
Paper: WEP1301
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1301
About: Received: 10 May 2026 — Revised: 19 May 2026 — Accepted: 21 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
WEP1347
FLUKA-Based Optimization of Pion Production for a Muon Collider Demonstrator
2307
This study uses FLUKA simulations to investigate pion production from proton interactions with a graphite target for muon collider applications. A 40 cm target is struck with 0.8 GeV and 8 GeV/c proton beams, and pion yields are evaluated in terms of angular and energy distributions. The dependence of pion yield on target length is also examined, showing saturation near one interaction length for the 0.8 GeV beam, and saturation near two interaction lengths for the 8 GeV/c beam due to secondary interactions. In addition to total production, a subset of “acceptable” pions is defined based on capture constraints (kinetic energy <400 MeV, forward-going, and escaping the target). The results show that while the 8 GeV/c beam produces higher overall yields, the 0.8 GeV beam provides a larger fraction of pions within the desired constraints. Charge asymmetry is also observed in pion production, with implications for muon beam balance and collider luminosity.
Paper: WEP1347
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1347
About: Received: 16 Apr 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP1349
Design and optimization of a horn focusing system for efficient pion capture in a Muon Collider Demonstrator
2311
This study investigates magnetic horn focusing as an alternative to superconducting solenoids for the Muon Collider Demonstrator. We explored a double horn structure as an R&D exercise for a possible muon-collider frontend, tailored to capture pions in the 100-400 MeV/c momentum range. An XGBoost-based optimization pipeline was applied to refine geometric and current parameters to maximize pion yield while maintaining acceptable emittance. To validate performance, we benchmarked the single horn structure against IMCC design baselines and compared the optimized double horn structure with the solenoid channel, using Geant4 and FLUKA simulations. The results provide a critical assessment of the trade-offs between the lower-cost magnetic horn approach and superconducting solenoids, offering a potential pathway for a more economically viable Muon Collider Demonstrator.
Paper: WEP1349
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP1349
About: Received: 28 Apr 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
WEP4302
The AGS with two Cold-Snakes
2396
To preserve polarization in the Alternating Gradient Synchrotron (AGS), two partial snakes are used to avoid both imperfection resonances and vertical in- trinsic resonances. One of these partial snakes is superconducting and the other is normal conducting, the cold and warm partial snakes. Simulations show that adding an additional cold partial snake improves polarization transmission for both polarized protons and polarized helions. In this configuration, the spin- tune gap for protons is large enough to accommodate both Qx and Qy . For polarized helions, the spin tune gap is large enough for both Qx and Qy to be well separated but the additional cold-snake provides lossless transmission across the very strong Gγ = 60 − νy can be achieved. This paper serves as an investigation into extraction above 15 GeV/u which is needed to support all snake precession axes of polarized helions in the Hadron Storage Ring.
Paper: WEP4302
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4302
About: Received: 12 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
WEP4320
High-Gradient Booster Linac for Multi-GeV Proton Radiography at LANSCE
2428
Increasing energy of proton beam at the Los Alamos Neutron Science Center (LANSCE) from 800 MeV to 3-5 GeV will improve radiography resolution ten-fold. This energy boost can be achieved with a compact cost-effective linac based on normal conducting high-gradient (HG) RF accelerating structures operating at liquid nitrogen temperatures (cryo-cooled). Such an HG booster is feasible for proton radiography (pRad), which requires short beam pulses at very low duty. The pRad booster starts with a short L-band section to capture and compress the 800-MeV proton beam from the existing linac. The main HG linac will be based on S- and C-band cavities. An L-band de-buncher at the booster end can reduce the beam energy spread if needed for pRad experiments. We are developing proton cryo-cooled HG standing-wave structures with distributed RF coupling for the booster. Prototype cavity structures at S- and C-band are designed and will be tested cryo-cooled to measure breakdowns at high gradients. The booster linac beam dynamics design will also be presented.
Paper: WEP4320
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4320
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEP4346
CST modeling of traveling-wave chopper structures for LANSCE and LAMP
2465
The Los Alamos Neutron Science Center (LANSCE) accelerator complex delivers both protons and negative hydrogen ions with various beam time patterns simultaneously to multiple users. An upgrade of its front end to a modern, RFQ-based version – a part of the LANSCE Accelerator Modernization Project (LAMP) – is now in the conceptual design stage. The LAMP will need fast beam choppers both in the low-energy transport (LEBT, 100 keV) before RFQ, and in the medium-energy transport (MEBT, 3 MeV) after RFQ. We use CST to model the existing LANSCE plate-coax helix chopper at 750 keV and to develop fast traveling-wave current structures for LAMP MEBT and LEBT beam choppers. A few structure types: plate-coax helix, meander-folded stripline on high-dielectric-constant substrate, and double-helix like at FNAL – are considered and compared. The structures must provide short rise / fall times of the deflecting electric field (1-ns class in MEBT), while still making possible for the chopper pulse generators to deliver the required voltages at high repetition rates.
Paper: WEP4346
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4346
About: Received: 13 May 2026 — Revised: 16 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
WEP4602
A Bayesian Optimization Study of the Longitudinal Localized Excitation Slow Extraction for the XiPAF-Upgrading Synchrotron
2482
The longitudinal localized excitation slow extraction method reduces the energy spread of the extracted beam by applying transverse excitation exclusively within specific phase intervals at the edges of the longitudinal phase space of the bunch. For localized square-wave excitation, conventional amplitude modulation formula struggles to achieve uniform beam spill, while the temporal uniformity of the extracted beam is crucial in radiotherapy and related physics experiments. The XiPAF-Upgrading Synchrotron (with a circumference of 39.96 m), developed from Xi’an 200 MeV Proton Application Facility, serves as a dedicated platform for the study and evaluation of single-event effects on core electronics for astronautics. We simulated the localized square-wave excitation slow extraction process using the SynTrack particle tracking code based on the XiPAF-Upgrading Synchrotron's parameters to extract low energy spread beam. Furthermore, a Bayesian optimization method was employed to refine the amplitude modulation curve of the excitation signa, thereby achieving highly uniform beam spill under low-energy slow extraction conditions.
Paper: WEP4602
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4602
About: Received: 16 Apr 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
WEP4616
Design of a compact 8-MeV proton linac for medical applications
2506
A 714 MHz proton linac was designed for medical applications. The linac aims for both sychrotrons and S-band linacs. Proton beams can be accelerated to 8 MeV with high transmission.
Paper: WEP4616
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4616
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
WEP4633
Design of a dual extraction system for the ultra-compact multifunctional cyclotron CYCIAE-36A
2531
The growing demand for medical isotopes and mobile neutron sources has motivated the development of compact and multifunctional accelerators. The China Institute of Atomic Energy has developed an ultra-compact superconducting cyclotron, CYCIAE-36A, capable of accelerating H₂⁺ and α particles and delivering proton and α beams for applications including ²¹¹At production, PET isotope supply, α-irradiation studies, and neutron imaging. The highly compact layout poses significant challenges for beam extraction. A dual extraction system combining electrostatic deflection and carbon-foil stripping is proposed under the constraints of superconducting magnets, RF cavities, and limited space. In this scheme, α particles are extracted using an electrostatic deflector, while H₂⁺ ions are extracted by stripping, enabling variable-energy proton beams in the opposite direction. Phase width control is critical for extraction efficiency. A fixed-phase selector was implemented in the central region to optimize α-beam extraction. Particle tracking simulations starting from the central region assume phase widths of 20° for α particles and 50° for H₂⁺ ions, yielding extraction efficiencies of 65% and 99%, respectively. In addition, the effects of 1st and 2nd harmonic magnetic field components introduced by the magnetic channels during precession extraction were analyzed, and corresponding compensation methods were developed to mitigate their impact on beam dynamics.
Paper: WEP4633
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4633
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
WEP4644
Longitudinal beam dynamics simulation for gold ion acceleration in the J-PARC MR
2542
The J-PARC Main Ring (MR) is a high-intensity proton synchrotron, which accelerates protons from 3 GeV to 30 GeV. In addition to protons, we are considering accelerating heavy ions to GeV/u energies in the MR as part of the J-PARC heavy-ion program (J-PARC HI). The heavy ions will be injected from the new heavy-ion injector into the J-PARC Rapid Cycling Synchrotron (RCS) and delivered to the MR. As the first stage of the program, Au ions are considered the ion species to accelerate. A full stripping beam of Au ions ($^{197}$Au$^{79}$ ) with an energy of 500 MeV/u is injected from the RCS to the MR. Au ions are accelerated up to 11.5 GeV/u and delivered to the hadron experimental facility. Since the change in revolution frequency during acceleration of Au ions is larger than that for protons, additional cavities dedicated to ion acceleration or modifications to the existing RF cavity will be needed to cover a wider frequency range. To estimate the RF system requirements for accelerating Au ions in the MR, we conducted a longitudinal beam dynamics simulation. In this presentation, we present the simulation results with various harmonic numbers and acceleration times.
Paper: WEP4644
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4644
About: Received: 15 Apr 2026 — Revised: 16 May 2026 — Accepted: 17 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
WEP4648
Empirical Orbit Correction for 3-GeV Proton Beam Transport in Fringe Field from Front Solenoid of Secondary Beamline
2552
A 3-GeV proton beam from a rapid cycling synchrotron (RCS) is provided to muon and neutron production targets at Materials and Life Science Experimental Facility by a 3-GeV RCS to Neutron facility Beam Transport (3NBT) line in J-PARC. In the 3NBT line, the 3-GeV proton beam is deflected in the vertical direction due to fringe field of a large aperture solenoid for capturing secondary particles from the muon production target located approximately 30 m upstream of the neutron production target. For correcting the orbit deflection and eventually the vertical beam position on the neutron production target, the beam position was measured as function of excitation currents for the coils of the solenoid. In this presentation, we report results of the measurement analysis and the orbit correction based on the empirical analysis.
Paper: WEP4648
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4648
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEP4649
Simulation-Based Optimization of a Bent Silicon Crystal for Beam Loss Reduction in the J-PARC Main Ring Slow Extraction
2556
Reduction of beam loss at the Electrostatic Septum (ESS) during the slow extraction process is one of the major challenges for the J-PARC Main Ring (MR) slow extraction operation, which aims to increase beam power beyond 150 kW. Researchers at the CERN SPS have reported that beam loss at the ESS can be effectively reduced by installing a bent silicon crystal upstream of the ESS to utilize its charged particle deflection effect. This paper reports on optimization studies using simulations to maximize the beam loss reduction effect when such a bent silicon crystal is installed upstream of the ESS in the J-PARC MR. Specifically, we report details on the following points: 1) The silicon crystal is bent using a method known as anticlastic deformation, which inherently causes deformation of the crystal in the vertical direction. In the J-PARC MR, where the vertical beam size is large, this vertical deformation has a non-negligible impact on the beam loss reduction effect and must therefore be taken into consideration. 2) We also evaluate the influence of errors in the bending angle, such as torsion, which are present in actual bent silicon crystals. 3) We assess the impact of particles scattered by the bent crystal that circulate the ring and return to the slow extraction straight section.
Paper: WEP4649
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP4649
About: Received: 18 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
WEP5007
Accumulator-to-Target Beam Transfer Line for ESSnuSB+
2587
The ESSnuSB project aims to generate an intense neutrino beam and the associated muon flux, using a 5 MW high-power proton driver, requiring precise and reliable transport of the accumulated beam to the target station. To achieve this, a dedicated transfer line guides the extracted protons from the accumulator toward the neutrino beam direction while meeting strict geometric constraints. The beam transfer line accommodates horizontal and vertical angular offsets of 16.8° and 2.29° using a compact sequence of horizontal and vertical dipoles, with quadrupoles ensuring controlled beam size and minimal losses. Simulations show that a lattice just over one hundred meters long successfully preserves beam quality and aligns the beam with the required neutrino direction. This guarantees stable, low-loss delivery of the beam to the downstream target system.
Paper: WEP5007
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5007
About: Received: 07 May 2026 — Revised: 16 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
WEP5050
Optimisation of the transition energy crossing optics in the CERN Proton Synchrotron
2684
In view of optimising the performance for the fixed-target experiments in the CERN accelerator complex, studies aimed at increasing intensity in the Proton Synchrotron (PS) are currently taking place. Measurements have revealed losses along the PS cycle for the high intensity beams destined for the nTOF facility, with the majority originating from the transition energy crossing. As well as beam intensity, the transverse beam characteristics were also identified to have an impact on the magnitude of losses, hinting to possible aperture limitations due to the optics perturbations of the transition energy crossing γτ-jump scheme. The possibility to modify the existing γτ-jump quadrupole position along the PS ring is examined, in an attempt to optimise the crossing in terms of losses and transverse parameter evolution.
Paper: WEP5050
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5050
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
WEP5077
Impact of a quasi-resonant AC dipole excitation on transverse beam splitting
2732
For multi-turn extraction at the CERN Proton Synchrotron, the beam is transversally split into five separate beamlets. It has been shown that an AC dipole excitation effectively controls the characteristics of these beamlets. For this purpose, the AC dipole is set in resonance with the horizontal betatron tune while the horizontal tune crosses the 4th-order resonance, creating a double-resonance condition, i.e. the simultaneous resonance between the horizontal tune and the AC dipole excitation. This increases the fraction of particles that are moved from the core to the islands. Further studies have revealed that shifting the AC dipole tune slightly, thereby breaking the double-resonance condition, distributes the beam more evenly across the beamlets. This paper examines this phenomenon by establishing a Hamiltonian model for a system with such a quasi-resonant AC dipole and studying it with numerical simulations.
Paper: WEP5077
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5077
About: Received: 04 May 2026 — Revised: 17 May 2026 — Accepted: 22 May 2026 — Issue date: 22 May 2026
WEP5111
Longitudinal microwave instability study at transition crossing in the CERN PS
2826
The beam quality of high-intensity proton and ion bunches in the CERN Proton Synchrotron (PS) is limited by a longitudinal microwave instability at transition crossing. This single-bunch instability manifests itself as a rapid longitudinal emittance blow-up and impacts, for instance, the intensity and bunch length to the AWAKE experiment. In this contribution, results of complete parameter scans are presented to experimentally establish the beam stability limits. These are compared to detailed tracking simulations with the BLonD code, including collective effects with the longitudinal impedance model, beam feedback loops, and the gamma transition jump. Remarkable agreement with measurements is obtained for the instability thresholds and micro-bunch structures. Nonetheless, the characteristics of the simulated instability strongly depend on the modelling of longitudinal space charge, which focuses the micro-bunches but also introduces significant numerical noise. The results improve the understanding of performance limitations due to transition crossing and guide future mitigation strategies.
Paper: WEP5111
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5111
About: Received: 11 May 2026 — Revised: 18 May 2026 — Issue date: 22 May 2026
WEP5112
Beam-loading compensation at transition crossing for mixed intensity bunches
2830
To produce beam for the nTOF and East Area experimental facilities at CERN, the Proton Synchrotron (PS) simultaneously accelerates two bunches with very different intensities. This combined acceleration cycle gains time and flexibility for beam sharing across the accelerator complex. However, to fulfil the demanding beam requests for future facilities like the Search for Hidden Particles (SHiP) experiment, a higher bunch intensity delivered to nTOF is essential to maintain the average flux at a reduced repetition rate. This further increases the intensity difference with respect to the low-intensity bunch for the East Area. In this contribution, longitudinal dipole oscillations triggered by the intensity-dependent phase jump at transition crossing are exposed. A mitigation technique is derived analytically and demonstrated in beam tests, by tuning one cavity of the main RF system to a separate harmonic of the revolution frequency. This allowed the elimination of dipole oscillations at transition crossing and the preservation of beam quality, even with a significant increase of the nTOF bunch intensity.
Paper: WEP5112
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP5112
About: Received: 17 Apr 2026 — Revised: 15 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
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
WEP6017
Towards Fully Automated Transfer Line Commissioning at the CERN Super Proton Synchrotron
2965
Beam commissioning of slow extracted beams from the CERN Super Proton Synchrotron (SPS) to the North Area experimental targets requires trajectory control through multiple transfer lines using corrector magnets—a process that traditionally demands significant expert intervention. Previous work demonstrated the feasibility of applying reinforcement learning (RL) for automated trajectory correction based on secondary emission monitor (SEM) split-foil intensity measurements, successfully centering the beam on target under nominal conditions. However, this approach fails when the beam is lost or its position exceeds the SEM's active surface, and when the corrector magnets' polarities are not known; common sources of uncertainty during commissioning. We present an extended multi-stage optimization scheme that addresses these critical limitations by automating beam threading when the trajectory exceeds the SEMs' acceptance, systematically identifying corrector magnet polarity configurations, and optimizing the impact angle to maximize beam intensity at the fixed-target stations, measured by scintillators arranged around the target. The threading algorithm employs quasi-random search combined with Bayesian optimization (BO) to center the beam in the SEMs, before handing over to the RL controller. The automated polarity determination uses online system identification to resolve sign ambiguities in the correctors, eliminating a common source of commissioning delays when using RL or other dedicated steering algorithms. Finally, BO is used to optimize the position of the movable SEM monitors at the targets' locations, maximizing target intensity.
Paper: WEP6017
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6017
About: Received: 13 May 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
WEP6022
Autoencoder Architectures For Beam Anomaly Detection And Statistical Distribution Characterization
2977
In accelerator facilities, the control and assessment of a high-quality beam delivery require capable monitoring systems, including both hardware and software components. In most accelerator beamlines, precise measurements and reliable beam delivery are critical factors in their operation. At the CERN IRRAD facility, the transverse beam profile carries the essential information about the beam properties of interest for materials and component irradiation. Precise measurements and reliable beam delivery are critical factors in its operation. Building upon the existing IRRAD-BPM (Beam Profile Monitor) instrument at CERN, we explore the possibilities of employing Machine Learning techniques, with special focus on Autoencoder (AE) architectures. Dealing with a critical system that involves high-energy protons and extreme radiation conditions, we developed an AE-based anomaly-detection system. Its architecture, based on multiple parameters, is a result of hyperparameter optimisation aiming for the highest separation of anomalous samples. Additionally, to mitigate the existing limited BPM coverage that cannot capture the full extent of the beam tails, we perform a measurement-space statistical inference using this AE architecture. Moreover, by using a Multi-Wire Proportional Chamber (MWPC) device also present on the IRRAD beamline, we improve the beam profile modelling within a data fusion-like approach.
Paper: WEP6022
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6022
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
WEP6023
Virtual beam position monitor for particle driven plasma wakefield accelerators
2981
Beam parameters at the interaction point (IP) of a particle driven wakefield accelerator (PWFA) are carefully controlled to optimize the output energy and beam quality. However, regardless of the parameters achieved, misalignments of beams at a PWFA IP has been shown to produce significant detrimental effects to the output energy and quality. Online monitoring of pointing stability, or beam jitter, at the IP is therefore essential to discern between beam quality optimisation needs and misalignment issues. However, it is not possible to use standard beam position monitors (BPMs) at these locations. Presented in this contribution is the demonstration of a proposed virtual beam position monitor (vBPM), applied to the IP of AWAKE. Upstream BPMs on the proton transfer line as used to infer the transverse position at the IP. A simulation study has been conducted to train a convolutional neural network (CNN) model to perform this inference. Dominant BPMs are highlighted, pointing towards areas of future optimisation to improve the proton beam jitter. Application to recent data collected at AWAKE is also presented, demonstrating the online reconstruction potential for future AWAKE runs.
Paper: WEP6023
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6023
About: Received: 12 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
WEP6054
Development of the 2 MeV Proton Beam Diagnostics Section in Preparation for Neutron Production at FRANZ
3050
The Frankfurt Neutron Source (FRANZ) at the Institute for Applied Physics in Frankfurt (IAP) is advancing toward the commissioning of proton beams up to 2 MeV. To support beam tuning behind the RFQ–IH acceleration chain, a dedicated diagnostics section is being installed downstream of the IH structure. The setup focuses on transverse beam characterization using scintillation screens combined with radiation-tolerant camera systems, enabling multi-angle (two-view) imaging of the proton beam under various beam-current and RF settings. Additional instruments include phase probes for energy and RF-phase monitoring, as well as a Faraday cup for current measurements. The camera-based diagnostics are designed to provide reliable visual feedback during early commissioning, particularly in an environment with limited access and the radiation levels typical for this region of the accelerator. This contribution presents the concept, implementation approach, and intended diagnostic capabilities of the camera-driven setup as FRANZ prepares for subsequent steps toward routine 2 MeV operation and the following delivery of the proton beam onto the lithium target for the first neutron production campaigns.
Paper: WEP6054
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-WEP6054
About: Received: 11 May 2026 — Revised: 17 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
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
TUI4M00
Accelerator Research for Proton Therapy
3410
Proton therapy is a powerful tool in the fight against cancer. The number of accelerators has increased tremendously over the last years. Patients are treated now at over 125 facilities world-wide, which is an excellent example of an extremely successful technology transfer from fundamental research to healthcare. Depending on the tumour species, local tumour control can reach very high levels, e.g. more than 96% for uveal melanoma. To minimize side effects and maintain tumour control, new treatment modalities like FLASH or Minibeams are investigated. For FLASH, dose rates should be higher than 40 Gy/s with treatment times below 0.5 s. Minibeams aim for spatial fractionation of the beam. Experiments on cells, organoids and animals have been promising. These new irradiation forms create challenges for the existing and future accelerators: Developments in beam delivery, beam adaptation, and dosimetry are necessary. This paper describes changes on control system, beam shutters, and beam scattering systems which allow now irradiation times of 10 ms with a precision in dosimetry of better than 3% for a Spread-Out Bragg Peak at HZB. The set-up of a target station for minibeams will be presented.
Paper: TUI4M00
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-TUI4M00
About: Received: 07 May 2026 — Revised: 18 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
THP3311
Hofmann stability charts revisited for PIP-II: from classical theory to assumption-free and ML-Driven maps
3805
The Hofmann stability chart remains a standard for visualizing parametric resonances in space-charge–dominated linacs, but its use typically relies on non-oscillatory Vlasov dispersion relations with simplifying assumptions (continuous focusing, KV phase space, linear optics, limited transverse–longitudinal coupling). We revisit the chart for the PIP-II linac along three tracks. (1) We reproduce the conventional maps in the (νz/νx, νx/ν0x) plane for relevant εz/εx, providing a validated reference. (2) We remove key assumptions by deriving stability surfaces directly from multi-particle tracking with realistic lattice discreteness, RF defocusing, solenoid/quad optics, and bunched-beam dynamics; local tunes and early-time growth rates are estimated from envelope oscillations and projected to the same coordinates. These assumption-reduced maps recover the canonical stopbands while revealing shifts and broadenings driven by tune modulation, non-KV distributions, and transverse–longitudinal coupling at PIP-II intensities. (3) We train a compact machine-learning surrogate that emulates the growth surface from zero-current optics, tune depression, emittance ratio, bunching factor, and selected lattice descriptors, enabling rapid scans and online working-point selection. We compare the three representations on representative PIP-II sections and discuss implications for commissioning guard bands, resonance avoidance, and routine operations.
Paper: THP3311
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP3311
About: Received: 18 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP4010
Short high-intensity bunches for the AWAKE experiment
3869
The AWAKE facility utilises high-intensity single bunches to drive resonant wakes in plasma for the acceleration of electrons. Twice shorter bunches are required from the CERN Super Proton Synchrotron (SPS) for the next phase of the experimental programme. In addition, the reproducibility of the bunch distribution and intensity is essential. This contribution summarises the key improvements to approach the new target parameters. An enhanced bunch production scheme was developed in the Proton Synchrotron Booster (PSB). It allows the preservation of the small longitudinal emittance during acceleration in the Proton Synchrotron (PS) without triggering an instability during the transition crossing. In addition, a double-voltage jump bunch rotation scheme has been implemented in the SPS, with radio-frequency (RF) voltage functions synchronised to the variable extraction time. The measurement results confirm the feasibility of achieving the target beam parameters.
Paper: THP4010
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4010
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
THP4011
Absolute energy and machine length calibration in the SPS
3873
This contribution presents the results of a recent absolute-energy and machine-length calibration of the CERN Super Proton Synchrotron (SPS) using two different particle species on the same magnetic cycle. A recent review of the SPS ring geometry and magnet alignments resulted in a change of machine circumference in the optics models to better approach the as-built machine. This measurement aims at measuring the real machine circumference based on the absolute energy calibrations, which then allow to accurately determine the circumference from the revolution period. The measurement repeats a similar exercise performed in the early 2000s, using the magnetic center of the sextupole as a reference, and complements using BPMs centers as well. Comparison between new and old measurements as well as models is shown.
Paper: THP4011
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4011
About: Received: 11 May 2026 — Revised: 20 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP4012
Beam performance reach at CERN PSB for the ISOLDE facility
3877
The Proton Synchrotron Booster (PSB) at CERN is the first synchrotron of the proton accelerator chain and provides beam not only to the LHC and the rest of the injector complex, but also serves directly ISOLDE. This facility is one of the most demanding users in terms of beam intensity, receiving more than 60% of the overall protons produced at CERN. To further optimize beam delivery while accommodating new beam users at CERN, systematic studies are conducted to identify the performance reach. Current efforts focus on maximizing the achievable intensity in the PSB and assessing the impact on the isotope production at the facility.
Paper: THP4012
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4012
About: Received: 13 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP4022
Accelerator development for the High Brilliance Neutron Source (HBS-I)
3911
Neutrons are an indispensable tool for science and industry to study the structure and dynamics of matter from the meso to the pico scale and from seconds to femtoseconds. An attractive way to provide urgently needed neutrons in the near future is to build efficient high-current, accelerator-based neutron sources (HiCANS) using pulsed proton beams. A new national research infrastructure that benefits significantly from these developments will be the High Brilliance Neutron Source (HBS-I), which was recently shortlisted by the Federal Ministry of Research, Technology, and Space (BMFRT). HBS-I uses pulsed 100 mA high-current proton beams to generate neutrons through a low-energy nuclear reaction at 20 MeV in a target material, which requires less radiation shielding and moderator cooling compared to conventional neutron sources. The facility is designed to produce small-diameter neutron beams, enabling experiments with smaller sample volumes. This will support research in materials and life sciences, including materials for energy conversion and storage, nanomaterials, quantum materials, protein structures, and biomaterials. The facility is intended for use by a multidisciplinary community of universities, research institutions, and industry. The basic concept and its realization will be presented.
Paper: THP4022
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4022
About: Received: 11 May 2026 — Revised: 21 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
THP4037
FFA magnet prototype for high power pulsed proton driver
3944
The Fixed Field Alternating Gradient (FFA) accelerator is a natural candidate for a high-power pulsed proton driver, although no high-power FFA has yet been constructed. As a critical component of the accelerator, the main magnets have been the subject of particular study. Operational flexibility, in terms of machine optics, over a large range is an essential feature of such a machine. In order to explore this in more detail a dedicated FFA prototype magnet has been designed and manufactured. This magnet was manufactured and delivered to the Rutherford Appleton Laboratory (RAL) in the UK in April 2025, and field measurements are subsequently planned to establish its characteristics. This paper will discuss the design, manufacture, and measurement plans of the prototype magnet.
Paper: THP4037
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4037
About: Received: 13 May 2026 — Revised: 19 May 2026 — Accepted: 21 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
THP4040
Simulation of Liouvillian multi-turn Injection for Direct Proton Accumulation
3956
In the ESS neutrino super beam (ESSnuSB) project, an efficient injection into the accumulator ring is required for minimizing beam loss during injection, reducing capital cost, and simplifying the overall project. To meet these requirements, the Liouvillian Injection Optimization (LIO) method has been developed for direct proton injection into the accumulator using a 4D multi-turn accumulation process without stripping. This method enables to paint both the horizontal and vertical phase-space simultaneously using a tilted septum. In this study, the LIO method has been investigated using the PyOrbit simulation code. The results demonstrate the method’s dependency to the lattice tune, the injected beam beta function, the close-orbit rout, and space-charge effects, which play a dominant role on the efficiency of the injection process. This work present the optimization of the method considering space charge effects, lattice nonlinearities, and considerations on its capabilities.
Paper: THP4040
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4040
About: Received: 13 May 2026 — Revised: 21 May 2026 — Issue date: 22 May 2026
THP4042
Investigations of a Novel Bunch Compression Technique for Hadron Accelerators
3960
Bunch compression is necessary for many accelerator applications, one of which being the creation of muons for the proposed muon collider. The design of a proton driver to deliver a short and very intense proton pulse to a target for the creation of muons is being developed. Some challenges with the proposed baseline design, notably the ambitious requirements for the radiofrequency system, motivate the investigation of alternative compression methods. A series of chirped bunch trains can be compressed in the same compressor ring as in the baseline design, removing the need for an accumulator ring and radiofrequency cavities in the compressor ring. Such a scheme has been investigated using PyORBIT simulations, where the chirp is created by off-frequency cavities at the end of the linac. The impact of space charge was investigated, and was found to be too detrimental for realising the proposed scheme with the current parameters. However, other use cases are foreseen.
Paper: THP4042
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4042
About: Received: 13 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP4046
Development of an Optical Beam Profile Monitor for the HZB Cyclotron
3972
The HZB cyclotron accelerator complex provides 68 MeV protons for proton therapy and related research. The main accelerator is an isochronous sector cyclotron served by two injectors. Originally, the cyclotron was designed for heavy ions. Hence, the beam profile monitors (BPM) on the high energy side are not appropriate for protons at the low intensities used for proton therapy. At the experimental station as well as the treatment station, the profile and shape of the beam is determined via a mirrored image of a scintillator screen in air. For the experimental station, a LabVIEW code has been developed which displays the shape, transverse beam distribution, size and position of the beam. As this tool proved to be very helpful when tuning the beam for experiments, an installation within the beam line in vacuum was designed for several locations where the beam is focused. The design of the new beam profile monitors and their performance will be presented.
Paper: THP4046
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4046
About: Received: 23 Apr 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
THP4048
Design and Optimization of a Fast Electrostatic Chopper for FLASH Proton Therapy Radiobiology Experiments.
3980
FLASH proton therapy has shown the potential to reduce normal-tissue toxicity while maintaining tumor control by delivering radiation in ultra-high dose-rate pulses (>40 Gy/s). However, more radiobiology experiments are needed to better understand the subjacent mechanism and optimize its application beam parameters. To explore this regime using the Cyclotron at Centro Nacionalicémoste de Aceleradores in Seville, we have developed a fast electrostatic chopper for length beam structure manipulation in order to be able to produce short (~1 um) and high intensity pulsed beams. In this paper, we present the design and optimization of this device, intended to generate well- defined beam pulses for radiobiology experiments in the FLASH regime. Electromagnetic simulations were performed with CST Particle Studio to define the electrode geometry, determine the required operating voltage, and carry out tolerance studies for the mechanical design. The designed chopper was integrated into a full TOPAS model of the external cyclotron beamline to evaluate the need of additional subsystems such as a collimator and to optimize the operational parameters. First studies carried out with this model are also presented.
Paper: THP4048
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4048
About: Received: 13 May 2026 — Revised: 22 May 2026 — Issue date: 22 May 2026
THP4049
Traces of the Vortex Effect in PSI Injector II
3984
Injector II is part of PSI's high intensity proton accelerator (HIPA) facility. It is to date the only cyclotron worldwide that makes use of the a space-charge driven effect ("Vortex Effect") which causes bunches not to expand but to "roll up" in the horizontal plane. The effect prevents the cyclotron bunches from expanding longitudinally so that the phase width stays unusually small and the former flat-top resonators could be replaced by normal accelerating resonators. The effect has been simulated in PIC-codes like OPAL and experimentally verified by bunch shape measurements. We present measurements of radial probes which contain residual traces of this effect and we show how it is used to analyze and fit the beam optics in the transfer line between Injector II and the Ring Cyclotron.
Paper: THP4049
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4049
About: Received: 12 May 2026 — Revised: 19 May 2026 — Issue date: 22 May 2026
THP4056
Machine physics studies for the MYRRHA Phase 1 linac at SCK CEN
3996
At the Nuclear Research Center SCK CEN in Belgium, the first phase of the MYRRHA project (an accelerator driven system) is under construction. Included in MYRRHA Phase 1 are a normal conducting injector linac (RFQ + CH cavities) and a super conducting linac (60 single spoke cavities), providing a CW proton beam of 4 mA and 100 MeV. In this contribution the recent changes to the MYRRHA Phase 1 linac design and the associated machine physics studies are reported. First of all, the layout of the MYRRHA linac was changed from two identical injector linacs each including a dog leg to one straight injector (for the MYRRHA phase 1) and a (future) second injector with a dogleg. The beam dynamics studies of the straight linac and two options for the second injector are presented. Secondly, the impact of a detailed mechanical integration of the beam line elements, which is a compromise between the ideal theoretical layout and a realistic and pragmatic implementation, on the longitudinal and transverse phase space distributions is discussed. Finally, the losses along the linac and their relation to the RFQ output distribution are presented.
Paper: THP4056
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4056
About: Received: 06 May 2026 — Revised: 17 May 2026 — Accepted: 17 May 2026 — Issue date: 22 May 2026
THP4061
The High Intensity ECN3 project and the SPS Beam Dump Facility at CERN
4006
The Search for Hidden Particles (SHiP) fixed-target experiment has been approved to lead the search for dark matter at CERN, which has so far evaded discovery at the Large Hadron Collider. To meet SHiP’s demanding beam and infrastructure requirements, the High-Intensity ECN3 (HI-ECN3) project has been mandated with upgrading CERN’s North Area and equipping its only underground experimental cavern (ECN3) with a new Beam Dump Facility (BDF) capable of exploiting the maximum slow-extracted proton intensity available from the Super Proton Synchrotron (SPS). This contribution summarises the key technical challenges currently being addressed in the HI-ECN3 technical design phase and outlines the schedule, developed in synergy with the ongoing North Area Consolidation project (NA-CONS), to complete the upgrade and deliver first beam to the BDF in 2031, ensuring SHiP data taking before Long Shutdown 4 (LS4).
Paper: THP4061
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4061
About: Received: 28 Apr 2026 — Revised: 19 May 2026 — Accepted: 22 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
THP4084
Evaluation of laser-assisted charge-exchange injection into the ESSnuSB+ proton accumulator
4059
Laser-based H⁻ charge-exchange injection offers an attractive alternative to conventional carbon-foil stripping for injection into multi-megawatt proton rings. In foil-based systems, foil heating and degradation, radioactivation, uncontrolled beam losses, and transverse emittance growth are factors limiting the achievable average beam power. In this work, we evaluate the feasibility of implementing laser-assisted H⁻ charge-exchange injection into the 5 MW ESSnuSB (European Spallation Source neutrino Super Beam) proton accumulator. The analysis is based on numerical and asymptotic solutions of the Schrödinger equation for a two-level model describing the interaction of a relativistic hydrogen atom with a Gaussian pulsed laser beam. We discuss potential reconfiguration of the ESS accelerator to minimize the bunch length and energy spread at the interaction point (IP) with the laser beam, as well as adjustments to the lattice of the linac-to-ring transfer line to maximize the stripping and injection efficiency. This project Funded by the European Union, Project 101094628. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them. This project has been funded in part by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)-Projektnummer 423761110.
Paper: THP4084
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4084
About: Received: 28 Apr 2026 — Revised: 18 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026
THP4088
RF-KO Extraction at CNAO for Clinical Beams
4067
CNAO is one of the few hadron therapy centres all around the world that produce both proton and carbon ions beams. It is based on a synchrotron in which the beams are extracted by a slow extraction mechanism that uses either a betatron core or an electrostatic exciter re-ferred to as RF-KO (Radio-Frequency Knock Out). The RF-KO extraction method has been commissioned and in May 2024 we started using RF-KO for proton treatments, while in June 2025 we started using RF-KO for carbon treatments. This paper illustrates characteristics of clinical beams and the impact on patient treatment, comparing the re-sults of the present extraction method with the betatron core one.
Paper: THP4088
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4088
About: Received: 05 May 2026 — Revised: 18 May 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
THP4100
Commissioning of Helium Beams at CNAO
4103
CNAO (Centro Nazionale di Adroterapia Oncologica) is one of the few hadrontherapy centres all around the world that produce both proton and carbon ions beams. It is based on a synchrotron in which the beams are ex-tracted by a slow extraction mechanism by means of either a betatron core or an RFKO electrostatic exciter. Recently a third source, AISHa-CNAO (Advanced Ion Source for Hadrontherapy), has been installed to produce new species to be used for clinical or experimental pur-poses. In this article, we show the commissioning status of the helium beams generated by the new source.
Paper: THP4100
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4100
About: Received: 05 May 2026 — Revised: 18 May 2026 — Accepted: 18 May 2026 — Issue date: 22 May 2026
THP4103
Modelling beam losses in CERN’s Super Proton Synchrotron with Xsuite
4107
Studies are ongoing at CERN's Super Proton Synchrotron (SPS) to understand the origin and distribution of observed beam losses. The existing equipment in the machine allows for dedicated measurements to identify bottleneck regions with higher losses. A well-suited and accurate simulation model of the SPS is indispensable to be able to study the impact of underlying beam dynamics on the loss distribution. This paper reviews the current state of the SPS model in Xsuite for loss simulations. The aperture model has recently been improved, and additional features can be enabled on demand, such as collimators and lattice non-linearities. Furthermore, the impact of the beam sagitta in bending magnets can be represented by introducing aperture offsets. This paper presents the results of the current setup, compares them to dedicated measurements, and outlines the next steps for further improvements.
Paper: THP4103
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4103
About: Received: 15 Apr 2026 — Revised: 19 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
THP4105
Mitigation of muon backgrounds at LHC forward-physics experiments through orbit bumps
4115
The Scattering and Neutron Detector at the LHC (SND@LHC), and the Forward Search Experiment (FASER), located on opposite sides of IP1 near the ATLAS detector, study high-energy neutrinos and dark matter produced from proton-proton collisions. A key challenge for both experiments is the muon background from the collisions and proton losses in the LHC ring. In 2024, a reversal of the triplet polarity in IR1 caused a substantial increase in muon background in both experiments. Although nominal triplet polarity returned in 2025, background levels remained significantly higher than in 2023. LHC FLUKA simulations transported to SND, supported by track directions observed in the data, indicated primary proton losses in the dispersion suppressor (cell 11) were the dominant source of the excess background, associated with the crossing plane change from vertical to horizontal. To mitigate these losses, orbit bumps were designed to displace the loss pattern away from cell 11. The bumps were designed using both conventional techniques and a novel Xsuite-based matching method employing beam losses as the optimisation observable. Experimental tests done in 2025 confirmed a background reduction in SND and FASER when activating the bumps. This study demonstrates that the proposed strategy is a viable operational solution for reducing muon backgrounds in future physics operations.
Paper: THP4105
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4105
About: Received: 12 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP4108
Towards a beam dump design for the HL-LHC: Analysis of Run 3 dumps and energy deposition studies on the HL-LHC TDE assembly
4123
In the Large Hadron Collider (LHC), two beam dumps (TDEs) ensure the safe and reliable disposal of the extracted beams. During Run 4, the stored beam energy will increase from 490 MJ achieved so far during Run 3 to a maximum of 710 MJ. A new design, capable of withstanding the increase in dump energy, is therefore presented for the High Luminosity LHC (HL-LHC) TDEs. This contribution includes an analysis of the beam energy actually dumped during Run 3, and presents energy deposition studies on the new design of the HL-LHC TDE. The energy absorption breakdown between the main components of the new TDE is presented, as well as the leakage to the surrounding shielding and cavern. Transverse and longitudinal peak energy densities are also shown, for standard dump events and considering failure scenarios in the beam dilution system.
Paper: THP4108
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4108
About: Received: 12 May 2026 — Revised: 20 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
THP4311
Second generation Fermilab Main Injector 8 GeV beamline collimation final design, installation and commissioning
4168
A novel transverse beam collimation system has been installed and commissioned in the Fermilab Main Injector 8 GeV beamline. The new collimation system compliments existing collimators and helps ensure the Fermilab Main Injector and Recycler accelerators are capable of handling the increased beam power promised from the Fermilab PIP-II upgrade, currently underway. This paper will present the final design and installation of the collimation system as well as initial results from its commissioning.
Paper: THP4311
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP4311
About: Received: 13 May 2026 — Revised: 20 May 2026 — Accepted: 21 May 2026 — Issue date: 22 May 2026
THP5605
Closed orbit and realignment in the CSNS RCS
4285
Closed orbit distortion (COD) is a critical factor affecting accelerator performance, and realignment serves as an effective measure to mitigate COD and reduce beam loss. The Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) currently suffers from significant beam orbit distortion, particularly in the horizontal plane, which limits its operational efficiency. To address this issue, a systematic analysis was conducted using the MADX accelerator physics simulation program, based on the alignment measurement data obtained in the summer of 2025. Through evaluation of alignment errors and comparison of different adjustment schemes, an optimized realignment strategy was proposed, involving transverse adjustments of four quadrupole magnets. Theoretical simulation results indicate that after realignment, the horizontal orbit distortion can be reduced by approximately 2 mm, and the vertical distortion by about 4 mm, leading to a significant improvement in overall orbit smoothness. Subsequent beam tests further validated the effectiveness of the strategy. The horizontal orbit was reduced by approximately 6 mm, and the vertical orbit by about 2 mm, compared with the pre-alignment state. This study fully confirms the critical role of realignment in optimizing beam orbit performance.
Paper: THP5605
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5605
About: Received: 12 May 2026 — Revised: 20 May 2026 — Issue date: 22 May 2026
THP5639
Design concept of ceramic chambers at the J-PARC RCS: an analytical perspective
4353
Ceramic chambers are essential for rapidly accelerating high-intensity beams at the J-PARC RCS, as they mitigate the effects of eddy currents on the chambers. An analytical perspective could provide valuable insight into the design of ceramic chambers, though computer simulations and demanding measurements need to certify the estimates. The identity of bending magnets, including chambers, is a key to reducing beam losses at the injection area of the RCS.
Paper: THP5639
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5639
About: Received: 15 Apr 2026 — Revised: 15 May 2026 — Accepted: 16 May 2026 — Issue date: 22 May 2026
THP5663
Hollow bunch method for improved spot dose accuracy in 3D PBS Proton FLASH
4390
A longitudinal localized kick-driven fast extraction technique has been employed to enable three-dimensional (3D) proton pencil beam scanning (PBS) at ultra-high dose rate (FLASH) for large-volume targets. However, it was observed that the longitudinal line density of the proton bunch significantly influences spot dose accuracy. In this study, a hollow bunch method—implemented by using two harmonic waves to manipulate the longitudinal phase space—is applied to reduce the line density in the extraction region. The RF parameters are carefully chosen so that the evolution of the phase space satisfies the requirements. Simulations conducted with the SynTrack code demonstrate that this method can effectively reduce the line density in the extraction region, thereby offering the potential to improve spot dose accuracy.
Paper: THP5663
DOI: reference for this paper: 10.18429/JACoW-IPAC2026-THP5663
About: Received: 15 Apr 2026 — Revised: 19 May 2026 — Accepted: 20 May 2026 — Issue date: 22 May 2026