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.

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 rectilinear cooling lattice used to compress the six-dimensional (6-D) phase-space volume of the beam comprises solenoids for strong focusing, dipoles to generate dispersion, wedge absorbers for differential energy loss, and RF cavities for longitudinal energy restoration. The International Muon Collider Collaboration aims to demonstrate the integration and reliable operation of a 6-D ionization cooling system, including RF acceleration in strong magnetic fields. This paper presents a full implementation of the Muon Cooling Demonstrator 6-D cooling lattice in BDSIM, together with an evaluation of its cooling performance.

The cooling process is one of the most critical challenges for the future Muon Collider, as muons are initially produced with a very large emittance that must be significantly reduced before acceleration. This cooling must occur rapidly, well within the muon lifetime. At low energies, collective effects such as space charge and intrabeam scattering can strongly influence emittance growth and must therefore be considered in the lattice design, which is currently under development. This work presents studies of space charge and intrabeam scattering effects within the first three cells of the latest Muon Collider final cooling lattice design evaluating their impact on emittance growth using the tracking code RF-Track.

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.

The Plasma Wakefield Acceleration (PWFA) experimental platform consists of two beamlines. Beamline 1 (BL1) transports the electron-positron beams from the BEPCII linear accelerator to the experimental station, with a beam energy of 2 GeV. Beamline 2 (BL2) is a linear accelerator featuring an energy of 150 MeV and a bunch charge exceeding 5 nC. Currently, both beamline accelerators have entered the beam commissioning phase. Pyapas, an independently developed High-Level Application (HLA) by the Institute of High Energy Physics (IHEP), has been successfully applied to beam commissioning of high-energy light sources. We have achieved the successful porting and application of Pyapas in the beam commissioning of the PWFA linear accelerators.

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.

Relativistic electron beam pulse compression can enhance the beam current intensity within the pulse and generate higher peak current, showing significant potential for applications such as FLASH radiotherapy and wakefield acceleration. This paper proposes a proof-of-principle experimental design for a solenoid-based electron beam pulse compression scheme. The core device of the experiment, namely the magnetic compressor, has an approximately cylindrical structure with a diameter of 42 cm and a height of 47 cm. By utilizing the uniform magnetic field generated by the solenoids, the compressor converts the energy difference of the injected beam bunch into a path-length difference to achieve pulse compression. Simulation studies show that, under a transverse geometric emittance of $10~\mathrm{mm\cdot mrad}$, the beam loss remains below 10%, while the output current waveform exhibits a peak-to-peak ratio of approximately 5, demonstrating an obvious pulse compression effect.

In this paper, the Non-dominated Sorting Genetic Algorithm II (NSGA-II), combined with the beam dynamics code ASTRA, was employed for the multi-objective optimization of the output performance of an electron linear accelerator (linac). Taking the pre-injector of a storage ring light source as an example, the electron linac consists of a thermionic cathode high-voltage electron gun, a sub-harmonic buncher (SHB), a buncher, and a traveling-wave accelerator tube. Maximizing the transmission efficiency and minimizing the energy spread were defined as the core objectives of the optimization. The optimization results indicate that the beam energy at the linac exit reaches approximately 65 MeV, with the transmission efficiency exceeding 70% and the energy spread maintained below 0.35%.

The University of Melbourne’s X-band Laboratory for Accelerators and Beams (X-LAB) is developing a compact electron linear accelerator. The injector system will consist of a 100 keV DC photogun, a pulsed UV laser, an S-band (2.9985 GHz) RF buncher, and magnetic elements for beam transport. This paper reports on the commissioning of the injector system. We present the characterisation of the test laser and buncher, as well as initial electron beam measurements with Faraday cup. Particle tracking simulations using General Particle Tracer (GPT) code were used to obtain approximate optimal solenoid currents. We also report on the conditioning of the photogun, including photocathode inspection, vacuum performance, dark current, and stray radiation.

Muon colliders require strong beam cooling to reduce the large phase space of muon beams produced from pion decay. The final stage of ionization cooling employs high-field solenoids, absorbers, and RF cavities, where precise beam matching is essential to avoid emittance growth. In this work, we present a beam-parameter–based approach to design and optimize solenoid lattices for the final cooling channel. The method models realistic solenoid fields and solves the coupled beam envelope equation while accounting for momentum changes in absorbers and RF systems. To implement this approach efficiently, we developed the Python package coolpy, which computes the evolution of Twiss parameters and optimizes matching coil settings. Two case studies demonstrate matched beam transport in solenoid-based beamlines.

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.

Super Tau Charm Facility (STCF) is the third-generation e+-e- collider under design and R&D with a circumference of about 800-900 m, a center-of-mass energy range from 2-7 GeV and design luminosity higher than 0.5 x 1035 cm-2 s-1, about 100 times higher than BEPC-II. To squeeze the beam for higher luminosity, compact twin-aperture high gradient interaction region superconducting magnet (IRSM) systems are required on both sides of interaction point (IP). The IRSM system consists of four twin-aperture superconducting quadrupole magnets. As part of the key R&D activities at accelerator CDR stage, full-scale twin-aperture QD1 quadrupole magnets were designed and constructed. The QD1 magnets have design field gradients of 50 T/m, field harmonics below 0.2‰, and site at 900 mm distance away from IP at beam crossing angle of 60 mrad. In this paper, details of QD1 design, construction and test are reported.

Low-emittance microbunched electron beams are a key ingredient in free-electron lasers (FELs), facilitating gain and coherence in radiation production. It has been proposed, such as by the Compact X-ray FEL (CXFEL) group at Arizona State University, that nano-scale microbunching could be produced by rotating transverse beamlets into the longitudinal plane. Such a technique could make short-wavelength FELs much more compact, reducing cost. Thus, a collaboration has been formed to test this principle using the emittance exchange (EEX) beamline of the Argonne Wakefield Accelerator (AWA).* ** This experiment will take micro-scale transverse modulations on a TEM grid and produce mico-to-nano scale microbunches. Performing this with AWA’s 40 MeV electron beam will require low normalized emittance (~50 nm*rad), and low charge (~1pC) electron bunches that are not commonly produced at AWA. These proceedings will detail our work to produce and characterize this low emittance in the AWA beamline.

The rectilinear 6D cooling channel is a key element of the Muon Collider baseline, enabling the large emittance reduction required before acceleration. The Muon Collider Cooling Demonstrator aims to validate, at engineering scale and in relevant conditions, the integration of a single B5-like cooling cell. This paper presents the preliminary design of the Cooling Cell, developed within the MuCol and IMCC collaborations, and based on a high-field HTS solenoid pair, a low-Z absorber, and a 3-cell 704-MHz normal-conducting RF structure. A key point of the design effort is the introduction of the Inter-Cell Cryostat, a compact architecture that closes the magnetic forces inside the cold mass while decoupling the RF and absorber assemblies at room temperature. This solution enables a feasible mechanical integration, compliant with lattice length constraints, and provides sufficient space for waveguides and diagnostics. However, it requires a remote-handling connection between each cell. The final cell layout incorporates the MAG2.4 HTS solenoids operating at 20 K, an updated RF cavity with thin Al foils, a LiH absorber module, cryogenic and thermal-shield structures, and pillow-seal vacuum interfaces designed for remote-handling assembly. The configuration that we present is a step toward demonstrating the feasibility of the cooling channel of the Muon Collider.

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.

The LANSCE Accelerator Modernization Project (LAMP) aims to modernize the existing LANSCE front-end technologies. Two existing 750-keV Cockcroft Waltons are planned to be replaced by a single radio-frequency quadrupole (RFQ), and a new 100 MeV DTL will be installed. The new LAMP front-end is required to deliver beams with similar timing patterns to what is currently delivered to the experimental stations. Using the physics model of the LAMP front-end, we evaluate errors and sensitivities of multiple transport components and study the effect on the beam instensity and timing.

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.

The muon collider is a promising facility for exploring new physics at the energy frontier, combining the advantages of lepton collisions with multi-TeV center-of-mass energies. Achieving the required luminosity requires reducing the six-dimensional (6D) emittance of the muon beam by several orders of magnitude within the muons’ limited lifetime. This reduction can be achieved through ionization cooling, which generally consists of two stages: initial 6D cooling and final transverse cooling. In this work, we present an updated lattice design for both rectilinear 6D cooling and final cooling channels. The optimized design achieves a factor-of-two reduction in the final transverse emittance, representing a significant step toward meeting the beam quality requirements of a future muon collider.

The 26.7 km long Large Electron Positron collider (LEP) was operated at CERN between 1989 and 2000. The most precise measurements of the Z boson mass and width were made possible thanks to high precision energy calibration of the LEP beams with resonant depolarization. Transversely polarized beams had to be established at LEP to achieve this goal, providing a rich legacy of data on polarized beams at beam energies around 45 GeV. The beam dynamics simulation package Xsuite was recently enhanced to track polarized beams and to evaluate the equilibrium polarization of beams and related quantities. Xsuite code benchmarking with LEP results on transverse polarization and resonant depolarization will be presented in this contribution.

A comprehensive electromagnetic and beam-dynamics model of the High Brightness Beam Test Facility (HB2TF) electron injector under development at INFN-LASA has been implemented using COMSOL Multiphysics. The model incorporates the DC photocathode gun and the low-energy transport line. Three-dimensional electric and magnetic field distributions were computed and employed for particle tracking within COMSOL, enabling analysis of field effects, mesh resolution impacts, and space-charge contributions. The resulting field maps were exported and imported into ASTRA and RF-Track simulation codes to perform cross-validation of beam dynamics. Comparative studies focus on transverse emittance, bunch length, energy spread, and sensitivity to field map resolution. This work establishes a validated modelling workflow for the HB2TF injector and provides crucial input for its optimisation and future commissioning.

Accurate and stable integration of charged-particle motion in complex magnetic fields is essential for beam-dynamics simulations in accelerators and beam lines. For the Xsuite simulation framework we have recently developed a spatially discretized Boris-like algorithm that advances particle coordinates using the longitudinal position as the independent variable. The scheme retains the symmetric kick–rotate–kick structure of the standard time-based Boris pusher, ensuring exact preservation of the total momentum magnitude and of the phase-space volume. We derive its formal properties using operator-splitting and backward-error analysis, showing that it is second-order accurate, and that the symplectic error scales quadratically with the integration step. Such properties are also verified by numerical tests on representative field distributions.

The ISOLDE Superconducting Recoil Separator (ISRS) at CERN is a rotatable high-resolution spectrometer able to separate reaction fragments induced by HIE-ISOLDE beams, from the lightest to the heavies nuclear species, at collision energies up to 10 MeV/u. The injection of the ISOLDE beam into this ring requires a more compact bunch structure, so a Multi-Harmonic Buncher (MHB) device was designed for this task. The MHB will operate at a frequency of 10.128 MHz, which is a 10 % of the linac frequency, and would be installed before the RFQ. The MHB was designed as a two electrodes system, and the RF signal composed for the first four harmonics of the fundamental frequency, is fed into the electrodes. The system was first tested in the laboratory upto the nominal power conditions. Prior to delivery of MHB to its final location in ISOLDE, it will be tested with ion source beam at ESS-Bilbao with a β equal to 0.00328. In order to measure the functionality and characteristics of the produced bunches, a set of diagnostics were foreseen. To evaluate beam transmission a set ACCTs and a Faraday Cup were employed, a Wien filter to measure energy, and a Fast Faraday Cup (FFC) for bunch length measurement. The preparation of the experiment along with the results are presented in this contribution.

The RUEDI (Relativistic Ultrafast Electron Diffraction & Imaging) ultrafast electron diffraction (UED) beamline aims to deliver MeV electron bunches for sub-10 fs timescale diffraction experiments. The achievable resolution of the diffraction pattern at the detector is determined by the quality and focusing of the beam at the sample, and the transport of the scattered beam to the detector. A beamline design is presented which allows for flexible illumination onto the sample and variable angular magnification. The pre-sample electron optics consists of two apertures and two single solenoid lenses followed by the post-sample optics which consists of two double solenoid lenses. Simulated results are used to demonstrate the range of capabilities of each system and show that RUEDI will be capable of producing the high-resolution diffraction patterns needed for a world-leading UED machine.

Insertion devices with longitudinally periodic fields—such as undulators, damping wigglers, and polarizing wigglers—play a central role in several stages of the FCC-ee injection chain. Accurate field models and efficient long-term tracking are required, as the strong longitudinal field variation cannot be captured reliably with standard multipole expansions. We introduce in the Xsuite simulation toolkit a general model for such devices based on a Maxwell-consistent series expansion of the magnetic field. The expansion is constructed from the on-axis field and its transverse derivatives and is implemented in BPMETH, which provides a direct interface to Xsuite. Particle tracking is performed using the Boris integrator. We assess the approach by comparing Boris integration with a multipole expansion and compare the convergence of the resulting tracking. This framework enables detailed optics and beam-parameter studies for synchrotron light sources, damping rings, and polarization systems.

High-quality electron beams are critical for imaging experiments that provide detailed microscopic structural insights into materials. The Very-High-Frequency electron gun, capable of operating in continuous and pulsed modes, is a preferable option. In this paper, we employ a tungsten tip with an apex radius of curvature approximately 100nm as a cold field emission cathode in the VHF gun and measure the beam charge, transverse emittance, and energy spread to characterize the beam quality. In preliminary experiments, we have achieved a normalized transverse emittance of 54.01nm·rad. With an electron gun power of 37kW, we obtained astrongbeamcurrentofapproximately 6µA, which remained stable and continuous for several hours in a single experiment. By using an aperture to block electrons with large divergence angles and adjusting the solenoid’s focusing strength, we propose to converge the target-energy electron beam onto the aperture, increasing its transmission rate and optimizing the energy spread. Prior to optimization, the energy spread was approximately 3.57% at 536keV when using a 20µm diameter aperture.

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 we present simulations of the Low Energy Beam Transfer Line (LEBT) and the 4-rod RFQ. The LEBT, including an ECR ion source, 2 solenoids and a pair of slits, matches the continuous proton beam to the entrance of the RFQ. The RFQ accelerates and bunches the beam from 30 keV up to 1.5 MeV. The effects introduced by space charge and their effect on the output distribution out of the RFQ will be highlighted. A comparative study of the RFQ beam dynamics simulation perforemd with the codes TOUTATIS and DYNAC will be presented.

CNAO is one of the few centres all around the world able to treat patients affected from cancer by proton and carbon ions beams. The clinical beams are produced by a synchrotron equipped with two ECR (Electron Cyclotron Resonance) sources. A third source, based on the AISHa (Advanced Ion Source for Hadron therapy) source of the INFN-LNS laboratory, has been installed in order to pro-duce new species that will be interesting both for clinical and R&D purposes. This paper shows the most important results along with the issues occurred and the solutions found during the first phase of the commissioning of the source with helium ions beams.

Tracking through RF cavities is complicated due to the presence of time-varying electric and magnetic fields, which are not amenable to algorithms developed for static fields. Many simulation programs use simplified models that neglect transverse focusing even though it can play an important role at low energies. Other programs track using field maps which can be slow and potentially non-Maxwellian (and therefore not symplectic) if interpolation is needed to calculate the fields. To avoid some of these problems, presented here is an RF cavity model which is symplectic and computationally efficient. Spin tracking is included and transfer maps of arbitrary order can be computed. Additionally, DC solenoid and multipole components can easily be included. This model is an extension of the work of Rosenzweig and Serafini extended to avoid the ultra-relativistic approximation. The model has been incorporated as part of the Bmad and SciBmad ecosystems of libraries and programs.

To measure spin precession in ultra-precise magnetic fields, a method for injecting a beam with a three-dimensional spiral trajectory has been developed. For example, a muon beam with a momentum of 300 MeV/c must be confined within a controlled storage region (radius 33.3 ± 1.5 cm, height ± 5 cm) in a solenoid-type storage magnet (central magnetic flux density 3 T) based on medical MRI technology, with the local magnetic field variation controlled to be less than 0.1 ppm. A vertical kick by magnetic field is required to suppress the motion in the axial direction of the solenoid, and trial calculations have shown that a pulsed magnetic field can be excited by applying a pulsed current with a half-sine waveform (peak current 1 kA, pulse width 120 ns, frequency 25 Hz) to a kicker coil with a radius of 37 cm and a height of 10 cm. Generating a magnetic field using an extremely fast pulsed current requires a calculation method that takes into account the transient response on the conductor surface, with a skin effect of approximately 35 μm. In this presentation, we will apply the OPERA model to the geometry of the current kicker field generating conductor, and discuss the modeling by practicable mesh on the conductor surface and the evaluation of the time-space distribution of the generated kicker field. In addition, we will also discuss the model calculation method including the wall of the vacuum chamber around the kicker device.