collider
MOZD2
Status of the baseline design for a 10 TeV muon collider
36
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. Also initial studies of possible sites are included.
Paper: MOZD2
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOZD2
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOCD1
Updated baseline design for HALHF: the hybrid, asymmetric, linear Higgs factory
53
Plasma accelerators promise significantly more compact, affordable and greener next-generation facilities, including linear colliders. While high-efficiency and -quality plasma acceleration of electron beams has been achieved, positron beams are much more challenging. The HALHF* (hybrid, asymmetric, linear Higgs factory) collider concept sidesteps the positron problem by accelerating them using RF cavities, while plasma acceleration to much higher energy is utilised for electrons. We report on an updated HALHF baseline design, which is more realistic, more upgradable to higher energies and includes additional capabilities such as positron polarization. Preliminary start-to-end simulations of the new baseline are also described.
Paper: MOCD1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOCD1
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
MOPM003
Lattice correction and polarization estimation for the future circular collider e+e-
260
Precise determination of the center-of-mass energy at the Future Circular Collider (FCC-ee) operating at the Z and W resonance energies relies on resonant spin depolarization techniques, which require a sufficient level of transverse beam polarization in the presence of machine imperfections. In this study, the FCC-ee lattice is modeled and simulated under a range of realistic imperfections, complemented by refined orbit correction and tune-matching procedures. The equilibrium polarization is computed within these realistic machine models to investigate the causes of polarization loss and explore potential improvements through lattice optimization. Additionally, spin tune shifts, which contribute to systematic errors, are estimated to support the precision requirements of the energy calibration experiment.
Paper: MOPM003
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM003
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM007
FCC-ee energy calibration and polarization - status and outlook
267
The Future electron-positron Circular Collider, FCC-ee, aims at high-precision particle physics experiments with beam energies from 45.6 to 182.5 GeV, corresponding to the Z-pole up to above the top-pair-threshold. These goals demand, among others, a precise knowledge of the center-of-mass energy and, hence, the beam energies. By depolarizing previously polarized pilot bunches and recording the change of polarization with a 3D polarimeter, it is aimed to determine the spin tune and thereby achieve a systematic uncertainty on the beam energy in the order of tens of keV. The latest progress of the work conducted by the FCC-ee energy calibration and polarization working group is reported here.
Paper: MOPM007
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM007
About: Received: 26 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM009
Optics tuning of the FCC-ee
275
The Future Circular Collider, FCC-ee, is a proposed next generation electron-positron collider aiming to provide large luminosities at beam energies from 45.6 up to 182.5 GeV. This collider faces a major challenge to deliver the design performance in the presence of realistic lattice errors. A commissioning strategy has been developed including dedicated optics designs, efficient beam-based alignment and optics corrections based on refined optics measurements. First specifications on main magnets, corrector circuits, and instrumentation have also been investigated. A summary of all these aspects is presented in this paper.
Paper: MOPM009
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM009
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM010
Emittance tuning of the FCC-ee high energy booster ring
279
The Future Circular Collider (FCC), in its leptonic configuration has been chosen by CERN as main proposition for the next high-energy collider. This project aims to achieve luminosities one to two orders of magnitude higher than ever. Feasibility studies have led to the definition of tolerances on magnet imperfections and correction strategies. This is crucial for ensuring the performance of one of the main elements of the acceleration chain, the High Energy Booster (HEB) ring. The efficiency and overall performance of these strategies greatly influence new magnet specifications and tolerances, affecting main optic functions. Horizontal and vertical orbit corrections use horizontal and vertical kickers, respectively. Skew quadrupoles address vertical dispersion and transverse coupling. Normal quadrupoles correct the horizontal and vertical phase advances. This study simulates the distribution of these four corrector types to minimize the equilibrium emittance at the extraction energy of 45.6 GeV. The calculated strengths of these correctors and the associated misalignments are presented. The study also discusses the limitations and drawbacks of the proposed correction strategy.
Paper: MOPM010
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM010
About: Received: 29 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM011
Bayesian optimization for IP aberration correction and luminosity tuning in FCC-ee
283
FCC-ee luminosity optimization relies on measuring realistic signals from Bhabha scattering, beamstrahlung, and radiative Bhabha photons. Initial assessments of beamstrahlung signals examine the change in luminosity, beamstrahlung power and vertex detector hits in response to waist shifts, vertical dispersion and skew coupling at the collision point. These ongoing studies aim to extract IP-aberration-related signals from the energy spectrum, angular distribution, power of beamstrahlung photons, the vertex detector hits and the luminosity. Furthermore, the study integrates all these signals into a machine-learning-based approach for luminosity tuning and optimisation.
Paper: MOPM011
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM011
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM017
Do transverse bunch tails produce luminosity?
307
Heavily populated transverse beam tails can be an issue for the operation and the performance of present and future particle colliders. In this respect, the tailoring of beam distributions through transverse halo scraping is a powerful technique for limiting beam losses and maximizing beam lifetime. By doing so, a portion of the bunch intensity is sacrificed, to the benefit of a reduced bunch transverse emittance. In this paper, we assess the impact on the luminosity performance of the LHC using such bunches, based on an analytical approach supported by numerical integration. In particular, we quantify the interplay between beam scraping, bunch intensity loss, transverse emittance reduction and collider luminosity performance.
Paper: MOPM017
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM017
About: Received: 26 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM021
Proof-of-principle experiment to reconstruct the trajectory of dust grains interacting with the LHC beams
323
Interactions of dust grains with the LHC beams cause beam losses that can trigger premature beam aborts or even quenches of superconducting dipoles. While the simulated motion and ionisation of dust grains inside the proton beam are in good agreement with measured beam-loss data, a direct measurement of the dust movement is not available. A novel method was developed that reconstructs the trajectory of a dust grain based on the different beam loss profiles of transversely displaced bunches. A proof-of-principle experiment to validate the method using a thin wire to simulate the dust grain was performed in June 2024 at the LHC. This paper describes the beam experiment, compares the achieved displacements with simulations, and shows the reconstructed trajectories. Finally, it is discussed how the method can be applied for real dust events occurring during LHC operation.
Paper: MOPM021
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM021
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM024
Operational experience with automated beam loss analysis in the LHC
335
Every high-energy beam dump event at the Large Hadron Collider (LHC) is analysed to assess the performance of the machine protection system and to identify anomalous behaviour. Analysing the loss pattern of nearly 4000 beam loss monitors, which depends on beam parameters and machine settings, can be time-consuming and requires expert knowledge. Therefore, an automated beam loss analysis tool was developed and deployed in operation in November 2023. It uses empirically derived beam loss thresholds that scale with relevant beam parameters to evaluate beam dumps for post-mortem analysis. The paper describes how the beam loss thresholds were derived and optimised and reviews their performance in proton and Pb-ion operation.
Paper: MOPM024
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM024
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
MOPM026
Baseline concept and future prospects for the FCCee collider top-up injection
343
The FCC-ee (Future Circular Collider) is a high-luminosity lepton collider study at CERN. Strong effects from quantum fluctuations, beamstrahlung, and Bhabha scattering limit the expected lifetime to well below one hour. Top-up injection continuously refills the colliding bunches to maximize the integrated luminosity. The current baseline aims at using conventional on-axis injection and a thin magnetic septum. However, the beam size at higher energy modes and the limited off-energy dynamic aperture at lower energy modes make the on-axis condition challenging to achieve. The conventional scheme also raises machine protection concerns, as the circulating beam is subject to a fast one-turn bump towards the thin septum during the injection process. This contribution presents the status of the top-up injection scheme for every energy mode of the FCC-ee collider. We then discuss the existing challenges and potential variations to the baseline scheme in view of mitigating operational challenges and machine protection risks.
Paper: MOPM026
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM026
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM027
Impact of ground motion on FCC-ee performance
347
The Future Circular Collider for electron-positron collisions (FCC-ee) is a proposed next-generation particle accelerator aimed at achieving high luminosity and precision for fundamental particle physics experiments. Its performance is sensitive to environmental factors such as ground motion, which can induce vibrations and misalignments in critical accelerator components. This paper presents a detailed study on the impact of ground motion on FCC-ee performance, with a focus on beam stability, alignment tolerances, and the complex interplay between ground motion and operational parameters. Using advanced simulations and analytical modeling, we evaluate the FCC-ee's sensitivity to various ground motion scenarios, ranging from localized, uncorrelated disturbances to correlated plane waves, and analyze their effects on the beam optics, orbit distortions, and overall beam dynamics. The findings provide valuable insights into the design and operational strategies required to mitigate ground motion effects, guiding future research and engineering efforts to ensure the successful realization of the FCC-ee project.
Paper: MOPM027
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM027
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM028
Interplay between sextupole settings and single particle instabilities during the FCC-ee commissioning
351
The Future Circular Collider of electrons and positrons (FCC-ee) is designed to achieve high luminosity at center-of-mass energies ranging from the Z boson peak to the top quark threshold. During the commissioning phase, specialized optics are essential to accommodate the dynamic needs of machine tuning and beam stabilization. This paper investigates the role of sextupoles in the various FCC-ee commissioning optics, focusing on their influence on nonlinear beam dynamics. Using advanced simulation tools, we analyze how sextupole configurations impact key performance indicators, including the dynamic aperture, emittance evolution and lifetime. Strategies for optimizing sextupole strengths are explored. The findings provide critical insights for the design and optimization of the commissioning optics, ensuring efficient and reliable ramp-up to nominal operation. These results are instrumental in refining the FCC-ee commissioning strategy, supporting its broader objectives for particle physics research.
Paper: MOPM028
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM028
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM029
Progress on the 10 TeV center-of-mass energy muon collider
355
A 10 TeV center-of-mass muon collider could serve as a next-generation high-energy lepton collider with substantial physics potential while offering a more compact footprint than other proposed machines. However, this collider presents unique challenges, largely due to the short lifetime of muons and their decay products. Specifically, the collider ring requires specialized designs to protect the magnets and detectors while ensuring negligible neutrino radiation at Earth's surface. The high required luminosity also imposes stringent constraints, including very small beta functions at the interaction points that lead to strong chromatic effects. To meet these challenges, high-field combined-function magnets are used to create a compact layout with minimal straight sections. Flexible momentum compaction arc cells are used to maintain short bunch lengths and local chromatic correction sections to address the chromatic aberrations from the interaction regions. This work presents recent advancements in the 10 TeV muon collider ring, including interaction region improvements to reduce beam-induced background and a study that investigates the impact of $\beta^*$ on the dynamic and momentum acceptance.
Paper: MOPM029
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM029
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM032
Simulations of losses from fast instabilities in the FCC-ee
367
The electron-positron Future Circular Collider (FCC-ee) is a proposed high-energy lepton collider that aims to reach unprecedented luminosity and precision in the measurement of fundamental particles. To fully profit of such performance, it is crucial to keep detector backgrounds under control and operate the machine safely. Due to the high stored beam energy and to a number of complex operational features required at FCC-ee (e.g. the top-up injection scheme), controlling the backgrounds to the physics experiments becomes even more challenging. Recent studies on collective effects have shown that high impedance in the FCC-ee can lead to fast rise-time instabilities, where the beam amplitude grows exponentially, leading to beam loss within a few turns. Although a feedback system is being developed to mitigate this instability, failure scenarios of this feedback system need to be explored. This paper presents the study of the effects of this instability, in order to understand the possible implications for the machine and the experiments.
Paper: MOPM032
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM032
About: Received: 21 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
MOPM033
Coherent plane ground wave impact on the FCC-ee beam centroid
371
The FCC-ee is a collider, proposed after the LHC era, based on a ring of approximately 90 km of circumference. It will have to be able to accommodate beams running at half the z-pole and tt ̅-pole with vertical Interaction point beam size less than 40 nanometer at the z. In the present studies, coherent ground motions are being explored with particle tracking tools such as MAD-X and analytics code. The effect of parameters, such as harmonics, phase, orientation, defining global vertical sine waves like motion, are hence being detailed. At the time of writing, several lattices are subject to investigations. The differences in term of beam centroid for the main lattices and energy running will also be exposed. The impact of these motions of the machine detector interface quadrupoles is discussed.
Paper: MOPM033
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM033
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM034
Modelling optics and beam-beam effects of SuperKEKB with Xsuite
375
SuperKEKB, located at KEK, is a second generation B-factory, providing beam to the Belle-II experiment. Optics design and simulation of SuperKEKB were previously performed using the optics code SAD, developed at KEK. In this paper, we present a new model of SuperKEKB using the tracking code Xsuite, developed at CERN. An alternative strategy for modelling the interaction region, with controllable final focus quadrupoles, has been adopted. Optics comparisons between the new Xsuite model and existing SAD model, as well as tracking simulations including beam-beam modelling are presented.
Paper: MOPM034
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM034
About: Received: 26 May 2025 — Revised: 01 Jun 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
MOPM036
Beam losses due to beam-residual gas interactions in the FCC-ee
383
The Future Circular electron-positron Collider, FCC-ee, is a design study for a luminosity-frontier and highest-energy e+e- collider with a 91 km circumference. In a circular machine, the interactions between the beam particles and the residual gas in the vacuum chamber may degrade the beam quality, potentially affecting the beam lifetime and the collider luminosity, and cause local beam losses. In addition, experimental backgrounds may be increased. Ideally, the vacuum system must be able to keep vacuum conditions sufficiently good so that beam-residual gas interaction effects are tolerable for collider operation. This paper presents a study of the beam loss distribution arising from beam-residual gas interactions in the FCC-ee, together with beam-gas lifetime estimates.
Paper: MOPM036
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM036
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM039
Updated monochromatization Interaction Region optics design for FCC-ee GHC lattice
395
Determining Yukawa couplings of the Higgs boson is one of the most fundamental and outstanding measurements since its discovery. The FCC-ee, owing to its exceptionally high-integrated luminosity, offers the unique opportunity to measure the electron Yukawa coupling through s-channel Higgs production at 125 GeV centre-of-mass (CM) energy, provided that the CM energy spread can be reduced from 50 MeV to a level comparable to the Higgs bosons’ natural width of 4.1 MeV. To improve the energy resolution and reach the desired collision energy spread, the concept of a monochromatization mode has been proposed as a new operation mode at the FCC-ee, relying on the Interaction Region (IR) optics design with a nonzero dispersion function of opposite signs at the interaction point (IP). A first optics design and preliminary beam dynamics simulations have been carried out for version 22 of the FCC-ee GHC lattice type. In response to the continuously evolving FCC-ee GHC optics, this paper presents an optimized updated monochromatization IR optics design based on the Version 2023 of the FCC-ee GHC optics.
Paper: MOPM039
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM039
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 06 Jun 2025
MOPM040
Optimized physics performance evaluation of monochromatization interaction region optics for direct s-channel Higgs production at FCC-ee
399
The measurement of electron Yukawa coupling ($y_{e}$) via direct *s*-channel Higgs production at $\sim$125 GeV centre-of-mass (CM) energy is significantly facilitated at the FCC-ee, provided that the CM energy spread can be reduced to a level comparable to the natural width of the Higgs boson. This reduction is possible through the “monochromatization” concept, which involves generating opposite correlations between spatial position and energy deviation in the colliding beams. Following initial parametric studies for this collision mode, three different interaction region optics designs, each featuring nonzero horizontal, vertical, or combined dispersion at the interaction point, have been proposed based on the Version 2022 of the FCC-ee Global Hybrid Correction optics. In this paper, we benchmark the upper limits contours on $y_{e}$ with simulated CM energy spread and luminosity using Guinea-Pig, in order to assess, optimize, and compare their physics performances.
Paper: MOPM040
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM040
About: Received: 28 May 2025 — Revised: 06 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 06 Jun 2025
MOPM041
Estimation of FCC-ee beam lifetime from full lattice tracking
403
Across its energy range, the beam lifetime at the Future Circular Collider $e^+e^-$ (FCC-ee) will be dominated by radiative processes occurring as a result of the beam-beam collision, namely by beamstrahlung and small angle radiative Bhabha scattering. Although approximate analytical expressions exist for estimating the lifetime, it is most accurately evaluated by performing multiparticle tracking simulations, due to the interplay of magnetic errors with non-linear forces due to the beam-beam interaction. This contribution presents the first comprehensive study of the FCC-ee beam lifetime including both effects, simulated with the Xsuite framework.
Paper: MOPM041
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM041
About: Received: 24 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM043
Comparison of particle in cell and soft-Gaussian beam-beam solvers
407
A crucial component for designing particle colliders is the assessment of beam-beam effects at collisions. Particle In Cell (PIC) solvers are popular numerical tools, which solve the Poisson equation for the electromagnetic (EM) potential $\Phi$ produced by the colliding beam's bunches spread on a discretized grid, and compute the Lorentz force acting on the particles subjected to the gradient of $\Phi$. The main limitation of this approach is the high computational cost, which can be alleviated at the expense of accuracy by using approximation techniques, such as the soft-Gaussian approximation, which assumes the bunch particles to have transverse Gaussian distributions. Both methods are widely used in the accelerator physics community. The Xsuite framework is the first multiparticle tracking tool, which aims to support both approaches. This contribution compares the performance of their Xsuite implementation.
Paper: MOPM043
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM043
About: Received: 24 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM044
Long-term alignment stability of the SuperKEKB tunnel
411
SuperKEKB is a double ring collider consisting of a 7 GeV electron ring and a 4 GeV positron ring with a circumference of 3 km built 11 m below the ground level. SuperKEKB was constructed by reusing the KEKB tunnel, which was originally excavated for TRISTAN accelerator in early 1980s. SuperKEKB utilizes “large angle nano-beam scheme,” where two low emittance beams collide with a large crossing angle at the interaction point and therefore it is more sensitive to any machine errors, such as magnet misalignment, than KEKB. Since the tunnel was built on soft ground, it has been seen that the initial magnet alignment is deteriorating year by year. Level changes of the monument markers on the tunnel wall and the floors on either side of the interaction point have also been observed. The vertical and horizontal positions of the cantilever cryostats of the final focusing superconducting magnet system are constantly monitored during the beam commissioning. The cryostat vertical position presents a correlation with the vertical vertex position in the Belle II detector. These variations and the effects of temperature and other environmental factors on alignment will be reported.
Paper: MOPM044
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM044
About: Received: 20 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 06 Jun 2025
MOPM047
Laser Compton backscattering for precision beam intensity control in the FCC-ee electron-positron collider
422
In this study, we explore the application of laser-driven Compton backscattering (CBS) as a method to precisely adjust and regulate the intensity of colliding particle bunches in the Future Circular Collider (FCC-ee). Maintaining a tightly controlled charge balance between collision partner bunches within a 3–5% tolerance is critical for mitigating the impact of beamstrahlung on bunch length and preventing flip-flop instabilities. We present a realistic design for the CBS optical beamline and provide detailed simulation results that demonstrate its performance in the FCC-ee. Our analysis includes the distribution of scattered positrons, illustrating the feasibility of CBS for achieving the stringent intensity control requirements in this next-generation collider.
Paper: MOPM047
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM047
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM048
Study of the coherent < x-z > instabilities for FCC-ee
426
This work examines the dominant coherent head-tail type (< x-z >) instabilities in the vertical plane of the FCC-ee collider, focusing on a mode analysis method with the Circulant Matrix Model (CMM) to assess instability mechanisms under the influence of beam-beam effects and transverse wakefields. While the impact of vertical plane instabilities have been already studied, different mechanisms are prominent in the horizontal plane. Understanding these mechanisms is crucial to identifying a stable working point at the Z energy. This study aims to advance the stability analysis and optimisation of FCC-ee at Z energy by investigating horizontal plane dynamics. Our findings indicate that mitigation strategies effective for vertical plane instabilities may not be sufficient and need to be adapted in order to ensure overall beam stability.
Paper: MOPM048
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM048
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM051
Beam dump transfer line design in FCC-ee
438
The Future Circular lepton Collider (FCC-ee) will be an e+e- collider with beam energy spanning from 45.6 GeV to 182.5GeV. When operating in Z-mode, it will deliver the highest luminosity ever obtained in any lepton machine worldwide, and the stored beam energy will reach up to 18 MJ. Due to synchrotron radiation damping, the beam vertical size will be on the order of a few tens of um corresponding to a maximum energy density of ~5 GJ/mm^2 in the collider ring. A dedicated beam dumping scheme is required to safely dispose this potentially disruptive beam. A transfer line is designed to increase the beam transverse size as much as possible and reduce the energy density of the beam at the dump. This contribution presents the dump transfer line design for the collider ring as well as related studies on machine protection.
Paper: MOPM051
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM051
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM067
Radiation load from radiative Bhabha scattering in the FCC-ee experimental insertions
471
The lepton Future Circular Collider (FCC-ee) at CERN provides electron-positron collisions at four interaction points (IPs) along a 91 km ring, with beam energies spanning from 45.6 GeV (Z pole) to 182.5 GeV (ttbar threshold). The radiation showers produced by these collisions can reach sensitive components of the surrounding machine elements, possibly affecting their performance and lifetime. This contribution examines the case of radiative Bhabha scattering, which generates off-momentum beam particles that can be lost downstream. Some losses occur already at the superconducting final focusing quadrupoles (FFQs), where they can cause quenches and degradation of the coil materials. In this work, the Monte Carlo code FLUKA is used to study the impact of radiative Bhabha in the experimental insertion regions of FCC-ee. The radiation load in the FFQs and the radiation levels in the nearby tunnel and machine elements are simulated for the Z-pole and ttbar operational modes. For the FFQs, a tungsten shielding layer with optimized thickness is proposed to mitigate the radiation load in the magnet coils.
Paper: MOPM067
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM067
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 06 Jun 2025
MOPM069
Power deposition studies for the FCC-ee halo collimation system
475
The Future Circular Collider (FCC-ee) at CERN requires a betatron and momentum collimation system for reducing particle backgrounds in the detectors, and for protecting the machine in case of excessive beam losses. The system is composed of primary and secondary collimators, which will be housed in one of the technical insertions of the 91 km ring. In this paper, we present a first assessment of the beam-induced power deposition in the collimators using FLUKA Monte Carlo simulations. We show that dedicated shower absorbers are needed in the collimation insertion, which intercept secondary particles from the halo collimators and reduce the energy leakage to the environment. A first optimization of the shower absorber configuration is presented, considering different absorber positions and absorber lengths. We demonstrate that the power absorption of the betatron collimation system can be increased from about 50% to over 80% by adding two shower absorbers between primary and secondary collimators.
Paper: MOPM069
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM069
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM085
Towards ATF3: Beam based alignment (DFS, WFS) corrections in the ATF LINAC and ATF2 beamline
512
The Accelerator Test Facility 2 (ATF2) serves as a critical platform for testing technologies and techniques aimed at advancing the next generation of linear colliders. The ATF2 is composed of a linear accelerator (LINAC), a damping ring, and an extraction line that includes a high-precision final focus system designed to achieve the small beam sizes necessary for future collider experiments. A key requirement for these systems is maintaining high beam stability to deliver the nominal beam parameters at the interaction point, where tight beam focusing and minimal emittance are crucial for optimal collision performance. Recent efforts have focused on developing and implementing advanced beam correction techniques to enhance stability and counteract disruptive effects such as unwanted beam dispersion and wakefields to prepare for the ATF3 upgrade. These correction strategies have been tested across the LINAC, damping ring, and extraction line, showing promising results in mitigating these adverse effects. In particular, these methods have demonstrated the ability to reduce transverse beam oscillations and preserve beam quality, thereby improving the precision of beam delivery.
Paper: MOPM085
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM085
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM092
Machine learning approach to MDI optimization for 3 TeV c.o.m. Muon Collider
528
The Muon Collider is a proposed future accelerator for very high energy muon collision. Since muons are heavier than electrons, the synchrotron radiation is negligible at this high energy, allowing to build a compact machine able to deliver Multi-TeV c.o.m. energy collisions, enabling precision measurements of the Standard Model quantities and search for new physics. A challenge of a muon beam is the Beam-Induced Background (BIB), a flux of particles in the detector generated by secondary interaction of muon decay products with the accelerator components. To deliver the required physics performance, the Machine Detector Interface design needs to include a shielding for the BIB. The proposed solution consists of cone-shaped tungsten shields inside the detector area. The nozzles reduce the BIB to a manageable level at the cost of reducing the detector acceptance. A careful optimization of the geometry is necessary to further mitigate the BIB and improving the detector acceptance to maximize the physics potential. This contribution aims at discussing the optimization achieved with machine learning algorithms in combination with FLUKA simulations for a 3 TeV c.o.m. Muon Collider.
Paper: MOPM092
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM092
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM109
Beam-based alignment techniques for the FCC-ee
557
The Future electron-positron Circular Collider (FCC-ee) is a proposed lepton collider for high-energy particle physics succeeding the Large Hadron Collider (LHC). Its ambitious design goals demand excellent orbit and optics control and, therefore, set strict limits on alignment tolerances. One approach to relax the mechanical alignment tolerances is Beam-Based Alignment (BBA), where the offset between magnet and position measurement is determined and can later be used to steer the beam towards the magnetic centre using corrector magnets. One of the key challenges of the FCC-ee is developing an accurate and fast BBA strategy for quadrupoles and sextupoles. A parallel BBA technique is evaluated and compared in simulations for the baseline and an alternative lattice for FCC-ee using Xsuite and is presented in this paper.
Paper: MOPM109
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM109
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM110
Target luminosity and luminosity integral achievement at VEPP-2000 collider
561
VEPP-2000 electron-positron collider operating in the beam energy range of 150-1000 MeV is the only machine originally designed to exploit Round Beams Concept which results in significant beam-beam limit enhancement. After long shutdown for injection chain upgrade VEPP-2000 resumed data taking with luminosity limited only by beam-beam effects. Thanks to extensive and thorough machine tuning the luminosity achieved L = 9 * 10^+31 cm-2s-1 at E=900 MeV that is above the design value. The stable operation resulted as well in high average data taking rate of 2-4 pb-1/day at top energies. In 2024 VEPP-2000 achieved the symbolic long-term milestone: integrated luminosity recorded by each of two detectors, SND and CMD-3, exceeded 1fb-1. This value was the target data volume written in the project physical program. Recorded data allows to study physics of light quarks with unprecedent precision. Recently published by CMD-3 collaboration e+e- -> pi+pi- cross-section measurement already changed the vision of muon anomalous magnetic dipole moment mystery - possible window to physics beyond the SM.
Paper: MOPM110
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM110
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM114
Estimation of systematic errors in the experiment on precise mass measure of Y(1S)-meson on the VEPP-4M collider
565
Error analysis and estimation of accuracy in the experiment on precise mass measurement of Y(1S)-meson on the VEPP-4M with KEDR detector collider was presented. The resonant depolarization technique with laser polarimeter was used for beam energy calibration.
Paper: MOPM114
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM114
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM115
Y(1S)-meson rest mass measurement on the VEPP-4M collider
568
A new high precision measurement of the Y(1S)-meson rest mass is being carried out at the VEPP-4M collider using the KEDR detector. The resonant depolarization method with the laser polarimeter has been employed for the absolute calibration of the beam energy. In the paper resent status of the experiment is discussed.
Paper: MOPM115
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM115
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPS025
Simulation studies and design updates for the nuSTORM facility
637
The neutrinos from Stored Muons (nuSTORM) experiment aims to create neutrino beams through muon decay in a storage ring, targeting %-level precision in flux determination. With access to two neutrino flavors, it enables precise measurement of $\nu$-A cross sections and exhibits sensitivity to Beyond Standard Model (BSM) physics. With muons in the 1-6 GeV/c momentum range, it covers neutrino energy regimes relevant to experiments like DUNE and T2HK. Additionally, nuSTORM serves as a step towards a muon collider, a proof of concept for storage rings, and a testbed for beam monitoring and magnet technologies. The lattice structure consists of a pion transport line and a racetrack storage ring based on a hybrid FFA design, with conventional FODO cells in the production straight combined with FFA cells in the return straight and arcs. This paper provides an update on the nuSTORM design and simulation efforts. It covers horn and lattice optimizations for producing and storing low-energy muons, describes tracking studies of the lattice to guide event normalization and presents the latest simulated neutrino fluxes.
Paper: MOPS025
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS025
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPS031
Preliminary results of crystal channelling optimisation in the LHC using reinforcement learning
657
The Large Hadron Collider (LHC) can operate with high intensity proton and heavy ion beams, both of which require a collimation system to ensure an efficient operation and to protect against damage to sensitive equipment along the ring. The crystal collimation scheme using bent silicon crystals as primary collimators was therefore introduced to improve the collimation efficiency for heavy ion-beams. The first operational deployment of crystal-assisted collimation was achieved in the 2023 Pb run. This demonstrated the required performance gain to safely handle high intensity ion beams, but undesired crystal rotation led to the loss of optimal performance during physics fills. The cause of this is thought to be mechanical deformation of the goniometer due to heating related to beam impedance effects. Hence, a conventional numerical optimiser was deployed to monitor and compensate for crystal angular errors based on a set of beam-loss monitors. The problem at hand, allows for the use of machine learning techniques to ensure continuous optimal channelling, minimising convergence time and eventually the optimization of crystals in multiple planes in parallel.
Paper: MOPS031
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS031
About: Received: 24 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
MOPS046
Beam loading for counter-rotating high-intensity beams in the Muon collider
700
Muon colliders promise an efficient path to a multi-TeV energy collider facility. In the greenfield study, the final stage of the acceleration chain is planned as a series of four rapid-cycling synchrotrons (RCS). In each RCS, the RF systems are divided into several sections and shared by the two counter-rotating muon bunches. The accelerator requirements are driven by the need to preserve a maximum number of muons by taking advantage of time dilation. Therefore, maintaining a high accelerating voltage throughout the chain is essential, imposing superconducting RF cavities in the GV range. However, the high bunch intensity of up to $2.7\times 10^{12}$ particles per bunch and the 1.3 GHz TESLA cavity’s small aperture will result in induced voltages in the MV range. In the muon collider, the induced voltage of the counter-rotating beams will additionally impact the cavity voltage. This contribution presents the cavity voltage modulation and its impact on the beam loss and stability in the strong transient beam loading regime.
Paper: MOPS046
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS046
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPS066
A Dipole Scheme for the Electron Storage Ring at the Future Electron-Ion Collider
750
The Electron-Ion Collider, which is currently being designed for construction at Brookhaven National Laboratory, will collide polarized electron beams (5-18 GeV) with polarized hadron beams (41-275 GeV) at luminosities up to 10^34 cm−2 s−1. The electron storage ring will contain about 750 dipoles. These dipoles must fulfill not only complex geometric constraints but also requirements set by spin polarization. 576 dipoles will be located in the arcs and arranged as super-bend triplets, which provide reverse bending at 5 GeV to increase the emittance and damping decrement. The rest will be situated in the interaction region and insertion regions around the ring. Tight orbit tolerances driven by beam-beam effects at the interaction point result in very tight field-ripple requirements. While these could be mitigated by powering all dipoles in series, due to the super-bend configuration the dipoles do not all scale similarly with energy. A novel scheme has been developed using variable-turn coil designs and trim coils to achieve the required fields across the energy range. This contribution presents the unique dipole layout developed for the electron storage ring.
Paper: MOPS066
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS066
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPS115
A muon beam facility at CERN to demonstrate muon ionisation cooling
786
The International Muon Collider Collaboration (IMCC) has been formed following the 2020 European Strategy for Particle Physics Update, with the goal of studying the feasibility of a muon collider at a centre of mass energy of around 10 TeV. One of the most challenging sections of a muon collider is the initial cooling before acceleration, due to the necessity to apply intense magnetic and electric fields to reduce the 6D emittance of the muon beam by 5 orders of magnitude in a very short time, to cope with the limited lifetime of muons (2.2 μs at rest). The IMCC proposes to build a Demonstrator to prove that all the involved technologies (RF, magnets, absorbers, beam instrumentation) can be built at the required specifications, and integrated in order to limit the length of the cooling sections to an acceptable value. Several options are being considered in different laboratories within the collaboration. This paper describes a possible implementation at CERN, in the existing TT7 tunnel.
Paper: MOPS115
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS115
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPS116
Optics design status for the muon collider rapid cycling synchrotrons
789
The baseline design for the high-energy complex of a muon collider consists of a chain of pulsed synchrotrons spanning an energy range from 63 GeV to the target collision energy of 5 TeV. This chain incorporates both normal and hybrid synchrotrons, featuring a combination of fixed-field superconducting magnets and pulsed normal-conducting magnets. Initial optics designs for the chain of synchrotrons have been completed, with optimization efforts focused on minimizing the aperture dimensions required for dipoles and quadrupoles. Preliminary tracking studies have also been performed to evaluate emittance preservation throughout the acceleration process.
Paper: MOPS116
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS116
About: Received: 02 Jun 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
TUBN3
Exceeding high-luminosity LHC performance targets during the 2024 Pb-Pb ion run
882
We review the 2024 Pb-Pb ion run at the Large Hadron Collider (LHC), in terms of the operational experience, the problems encountered and the main results. This run was the second heavy-ion physics period of LHC Run 3 at 6.8 Z TeV. With only 18 days scheduled for physics data-taking, the key objective was to address the problems encountered in the 2023 Pb-Pb run and establish stable and efficient operation. Thanks to several mitigation measures, the 2023 limitations were overcome, significantly improving the machine availability. Together with substantially higher intensity, thanks to the excellent performance of the Pb ion injectors, this paved the way for a record-high performance in terms of average daily integrated luminosity with ion beams at the LHC.
Paper: TUBN3
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUBN3
About: Received: 15 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
TUPB029
Simulations of beam halo distributions for a feasibility study of in-vacuum gravitational experiments at the LHC
1009
Within the realm of general relativity, the measurement of signals coming from relativistic celestial bodies have offered great insights. However, the relatively low frequency of these signals and the lack of control over their source may make the creation of well-controlled laboratory environments desirable. One possibility is to measure the relativistic beams in the Large Hadron Collider (LHC) at CERN using a milligram-scale monolithic pendulum. This would offer the possibility to test general relativity and alternative theories of gravity in an entirely new parameter regime, where the source of gravity is the almost pure kinetic energy of the ultra-relativistic particles. The low-bandwidth of the source, combined with the controllability of the setup, may offer new opportunities and insights in gravity-related research. To design the experiment, it is necessary to analyze the factors that contribute to the deterioration of the signal-to-noise ratio. One of the contributors is the impact on the pendulum of beam halo particles. This paper presents an initial assessment of the impact of beam halo on the detection of gravitational signal.
Paper: TUPB029
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB029
About: Received: 26 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
TUPB065
Base features of electron cooling systems for NICA collider
1086
The project NICA (Nuclotron-based Ion Collider fAcility) aims to provide colliding beams for studying heavy ion collisions in the energy range 1-4.5 GeV/u. Obtaining maximum luminosity of the collider requires powerful longitudinal and transverse cooling at collision energy. That will be achieved with usage of both stochastic and electron cooling. The 2.5 MeV electron cooling system (ECS) includes two coolers, which cool ion beams in both rings simultaneously. The Budker Institute of Nuclear Physics (BINP SB RAS) already built and commissioned the electron cooling system for the NICA Booster with a maximum energy of 50 keV and now it develops the high voltage electron cooling system for the collider. This article describes the status of the ECS development.
Paper: TUPB065
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB065
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
TUPM076
Refined FLUKA simulation model of neutrino-induced effective dose from a multi-TeV muon collider
1303
Most muons injected into a muon collider decay into an electron (or positron) and a neutrino-antineutrino pair, producing a narrow disk of high-energy neutrinos emitted tangentially to the beam in the collider plane. These neutrinos reach the Earth’s surface at distances far away from the collider. Vertical diffusion of the neutrino cone, reducing integrated neutrino flux at any surface exit point, has been proposed as mitigation technique. This study presents effective dose calculations performed with the FLUKA Monte Carlo code for various geometrical models, each representing conservative radiation exposure scenarios from neutrino flux emerging from the ground at specific distances from muon decay points. These scenarios correspond to different parts of the muon collider ring: bending sections and long straight sections housing experiments. Results are provided as effective doses for annual exposure scenarios with a 100% occupancy. Two muon beam energies are considered: 1.5 TeV and 5 TeV, with a more detailed approach applied to the higher energy.
Paper: TUPM076
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM076
About: Received: 27 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
TUPM077
New developments in the design of the muon production target area of a multi-TeV muon collider
1307
As the International Muon Collider Collaboration advances the conceptual design for a multi-TeV muon collider facility, new technical constraints continue to arise in the muon production stage, where a high-power proton beam interacts with a target. Achieving the required muon bunch intensity may necessitate increasing the primary beam power up to 4 MW. Consequently, the shielding design must address sustained radiation exposure, particularly on critical components such as superconducting solenoids, which generate strong magnetic fields essential for capturing both pions and decay muons. Additionally, the portion of the proton beam that passes through the target without undergoing inelastic interaction leads to a very high power density in the chicane area and an intense ionising dose on the insulation material of the normal-conducting chicane magnets, which are used to separate the muon component. A robust method to safely extract these spent protons is crucial. This study presents the latest results from FLUKA Monte Carlo simulations, modelling the radiation load on solenoids and the extraction channel across varying beam power and target designs.
Paper: TUPM077
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM077
About: Received: 27 May 2025 — Revised: 01 Jun 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
TUPS012
ABEL: The adaptable beginning-to-end linac simulation framework
1412
We introduce ABEL, the Adaptable Beginning-to-End Linac simulation framework developed for agile design studies of plasma-based accelerators and colliders. ABEL’s modular architecture allows users to simulate particle acceleration across various beamline components*. The framework supports specialised codes such as HiPACE++, Wake-T, ELEGANT, GUINEA-PIG and CLICopti, which facilitate precise modelling of complex machine components. Key features include simplified models for addressing transverse instabilities, radiation reactions, and ion motion, alongside comprehensive diagnostics and optimisation capabilities. Our simulation studies focus on the HALHF plasma linac, examining tolerances for drive beam jitter, including effects of self-correction mechanisms. Simulation results demonstrate ABEL's ability to model emittance growth under transverse instability and ion motion, highlighting the framework’s adaptability in balancing simulation fidelity with computational efficiency. The findings point towards ABEL’s potential for advancing compact accelerator designs and contribute to the broader goals of enhancing control and precision in plasma-based acceleration.
Paper: TUPS012
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS012
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
WEPB029
Transient finite-element simulations of fast-ramping normal-conducting magnets for a 10 TeV muon collider
1756
Ongoing conceptual studies for a 10TeV muon collider identified rapid cycling synchrotrons as major engineering challenge. Due to the muon’s short lifetime of only 2.2µs at rest, normal-conducting bending magnets with field rise rates of well beyond 1kT/s are indispensable to support accordingly fast acceleration cycles. Energies of 100MJ will be interchanged between magnets and capacitor banks within few milliseconds. Accurate models of the magnets are thus required to optimize the overall system performance. The non-uniform temperature distribution in the magnet strongly affects material properties like the electrical conductivity of copper and must therefore be considered in the electromagnetic field problem. This contribution presents recent advancements in addressing this multi-physical problem by using problem-specific finite-element tools allowing to describe the inherently transient behavior. The ferromagnetic yoke is accurately resolved by using a novel combination of a Bergqvist hysteresis and a homogenized eddy current model. Finally, different magnet design concepts are compared in terms of material costs, magnetic energy, losses, field quality and temperature buildup.
Paper: WEPB029
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB029
About: Received: 22 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 06 Jun 2025
WEPB036
Nanometer sensitive vibration measurement system R&D status for SuperKEKB final focus
1772
SuperKEKB, a double ring circular collider with 7 GeV electron and 4 GeV positron beams, utilizes “nano-beam collision scheme” in which low emittance beams collide at large crossing angle. Positional fluctuations of the colliding beams are predicted to have a deleterious impact on luminosity; therefore, it is important to measure position oscillation of its superconducting quadrupole Final Focus (FF) magnets. KEK has developed, in collaboration with Brookhaven National Lab, a stabilized pickup-coil system to measure the magnetic field center oscillations of FF quadrupoles. This system is currently undergoing checkout and calibration at KEK using a permanent magnet quadrupole as a FF stand-in. In this paper, we will report on the measurement system status and our calibration results. This work is relevant for any high-luminosity collider that uses few-nanometer sized beams such as the proposed future ILC and FCC-ee Higgs Factories.
Paper: WEPB036
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB036
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
WEPB084
Design of normal conducting quadrupoles for the spin rotator section in the EIC electron storage ring
1872
The interaction region IR6 in the Electron Storage Ring of the planned Electron Ion Collider facility at Brookhaven National Laboratory includes a section to rotate the electron spin into or out of the longitudinal direction. This section consists of superconducting solenoids, and normal conducting dipoles and quadrupoles. The geometry and field gradient requirements of the quadrupoles pose a challenge in their design with regards to yoke saturation and thereby field quality. Electromagnetic design of one such quadrupole is the focus of discussion in this article. The design process involves optimization of the pole tip, yoke and conductor size using two and three-dimensional finite element method tools.
Paper: WEPB084
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB084
About: Received: 22 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
WEPB108
A TM020-mode cavity with choke geometry for Super Tau-Charm Facility
1897
To meet the requirements of collider rings of Super Tau-Charm Facility (STCF) with a beam current of up to 2 A, a TM020-mode cavity with improved performance is designed in this paper. In order to address the issues of leakage of accelerating mode into the slots which has dampers inside, a choke geometry is introduced for this cavity. Through optimizations on this choke, the accelerating mode is fully reflected back into the cavity and all of harmful modes can be heavily suppressed. In addition, the nose shape and frequency tuner are also optimized in detail.
Paper: WEPB108
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB108
About: Received: 03 Jun 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM015
Optics function determination using luminosity data
1941
Determining the betatronic waist shift and the $\beta^*$ at the interaction points through K-modulation in the Large Hadron Collider presents considerable challenges. This paper introduces a novel method for the measurement of these quantities, based on luminosity measurements and the van der Meer technique for reconstructing transverse bunch profiles. The strategy involves colliding multiple bunches with distinct emittances, performing emittance scans, and subsequently shifting the collision point along the longitudinal plane via RF cogging. This shows promising potential to reduce uncertainties in the optics parameters at the interaction point and to obtain measurements of the absolute beam emittance. The first measurement using this technique was carried out at the Large Hadron Collider, with the analysis and findings discussed in detail.
Paper: WEPM015
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM015
About: Received: 23 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM018
Optimizing beam-beam beta-beating for luminosity enhancement at the LHC
1949
The optimization of LHC operation is focused on achieving the highest possible integrated luminosity to maximize experimental data collection. Given the limitations of current detector systems, maintaining a constant level of integrated luminosity has become more critical than achieving a high peak luminosity. Techniques such as beta-leveling and separation levelling have already been implemented to adjust luminosity and enhance operational efficiency. This study describes how the beam-beam beta-beating effects propagating between the multiple experimental interaction points can serve as an additional mechanism to further increase the total integrated luminosity. The operational solutions and impact on performance will be shown for both the current LHC and its future High Luminosity upgrade.
Paper: WEPM018
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM018
About: Received: 23 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
WEPM035
Resonance Driving Terms characterization at VEPP-2000 collider
2001
The VEPP-2000 collider is a compact machine, which uses the round-beam concept to achieve high luminosity. Its compact size (24 m in circumference) limits the free space between the magnetic elements. Only 4 BPMs are installed in the ring with large phase advance between them (~2 pi). The key to improve its luminosity is to reduce the power of resonances. The implementing of the RDT measurement technique with our limitations is discussed. The presented experimental data gives basic information on the location of the considered magnetic perturbation causing the RDT.
Paper: WEPM035
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM035
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM062
Advances in machine learning inference of dynamic aperture evaluation for the LHC
2066
Dynamic aperture (DA) is a crucial metric for understanding nonlinear beam dynamics and particle stability in circular accelerators like the Large Hadron Collider (LHC) and its future High-Luminosity LHC (HL-LHC) upgrade. Traditional methods for DA evaluation are computationally intensive, requiring extensive tracking of large particle ensembles over many turns. Recent advances in machine learning (ML) have shown that models, particularly architectures like Bidirectional Encoder Representations from Transformers (BERT), can significantly accelerate DA predictions while achieving accuracies comparable to traditional simulations. Enhanced uncertainty quantification techniques further improve model reliability, providing a foundation for robust active learning frameworks. This work presents the latest progress in DA inference, focusing on architectural advances, data preparation, and optimised training techniques. Applied to LHC tracking data, these improvements highlight the importance of high-quality data generation and customised training strategies for enhancing model performance and uncertainty management, paving the way for future HL-LHC studies.
Paper: WEPM062
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM062
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
WEPM074
Impact of the geometric impedance of collimators on beam stability in FCC-ee
2094
Beam stability in the FCC-ee collider is strongly influenced by transverse and longitudinal beam coupling impedance. Developing a flexible and comprehensive impedance model is crucial for accurately evaluating and mitigating instabilities as machine parameters evolve. This study investigates the effect of the FCC-ee collimation system, identifying it as a dominant source of total machine impedance. Both resistive and geometric contributions are analyzed, with geometric effects found to play a critical role in shaping the overall impedance landscape. Accurately modeling collimators’ geometric impedance is essential for beam stability assessment. Such modeling enables global impedance considerations, accounting for the interplay between different accelerator elements and guiding the definition of critical design parameters.
Paper: WEPM074
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM074
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPS036
First proton crabbing at the LHC via head-on beam-beam interaction
2278
The first experimental observation of a 10 $\mu$m crabbing orbit at 1~$\sigma_z$ induced by head-on collisions with a non-zero crossing angle ($\theta_c$) in a high-energy proton beam at the LHC is presented. This challenging measurement required both the design of a dedicated experiment and a careful calibration and optimization of the beam instrumentation to produce and detect such a subtle effect. By varying the crossing angle from positive to negative values the reversibility of the effect and its dependence on the crossing angle were also demonstrated. Lattice simulations were performed to corroborate the experimental results, showing excellent agreement with the measured crabbing amplitudes. This experiment highlights the potential of the existing wideband beam-position monitors to diagnose crabbing effects, which will be crucial in the HL-LHC upgrade.
Paper: WEPS036
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS036
About: Received: 19 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
WEPS050
Electron cloud mitigation techniques for the FCC-ee
2315
The Future Circular Collider (FCC)-ee is a planned electron-positron collider under development. The future collider would be built in an about 91 km ring-shaped underground tunnel located beneath the French departments of Haute-Savoie and Ain, and the Swiss canton of Geneva. The FCC-ee may face challenges from electron cloud (e-cloud). The strongest effects are foreseen for the Z configuration, due to the highest number of bunches, which corresponds to the smallest bunch spacing, which is a key parameter for the e-cloud formation process. A high electron density in the beam pipe could limit the accelerator’s achievable performance through various mechanisms, such as transverse instabilities, transverse emittance growth, particle losses, vacuum degradation and additional heat loads on the inner surface of the vacuum chambers. In the design phase, the objective is to suppress the e-cloud effects in the FCC-ee. Therefore, effective e-cloud mitigation techniques, to avoid the e-cloud avalanche multiplication and its deleterious effects, are discussed in the paper.
Paper: WEPS050
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS050
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
WEPS051
Filling pattern with non-uniform bunch spacing to mitigate e-cloud for the FCC-ee
2319
The Future Circular Collider (FCC) study is developing designs for higher performance particle colliders that could follow on from the Large Hadron Collider once it reaches the end of its high-luminosity phase. In particular, the FCC-ee is a proposed electron-positron collider that may face challenges from the electron cloud (e-cloud). Specifically, the Z configuration foresees the highest number of bunches. Consequently, this configuration could suffer more form the deleterious effects of the e-cloud, such as transverse instabilities, transverse emittance growth, particle losses, vacuum degradation and additional heat loads on the inner surface of the vacuum chambers. The e-cloud effects have been observed in several circular accelerators all over the world and it is much more commonly in those operated with positively charged particles. Presently, it is among the major performance limitations for high energy collider. Therefore, the study of e-cloud mitigation techniques is crucial during the accelerator's design stage to suppress the e-cloud avalanche multiplication. This paper analyses the use of non-uniform bunch spacing patterns as a potential e-cloud mitigation strategy.
Paper: WEPS051
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS051
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
WEPS090
Touschek effect in Super Charm Tau factory
2366
Super Charm Tau factory is a proposed electron-positron double ring collider with crab waist collision scheme operating in wide beam energy range from 1.5 GeV to 3.5 GeV with peak luminosity of 10^35 cm^(-2) s^(-1). The polarized electron source and three Siberian Snakes provide 80% longitudinally polarized electron beam at 2 GeV. Superconducting wigglers decrease damping times, effects of intra-beam scattering and increase Touschek beam lifetime, particularly at low energy. This work presents studies of the Touschek effect in SCTF, as well as the results of a simulation of Touschek scattering, MOGA optimization of local momentum acceptance, and an investigation into the dependence of the dynamic aperture and the Touschek lifetime on the average orbit error.
Paper: WEPS090
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS090
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
THPB017
Magnetohydrodynamic effects in liquid lead target concept for Muon Colliders
2493
The use of liquid lead as a target material in particle accelerators is of significant interest due to its high density, high thermal power absorption capacity, and resistance to radiation damage. This makes it particularly well-suited for the high-intensity proton beams being studied for CERN’s Muon Collider proposal, with powers ranging up to 4 MW. To minimize shock propagation and manage the intense thermal and mechanical stresses induced by the high-power proton beam, a free-falling liquid lead curtain is explored as a promising concept. However, the target region requires strong magnetic fields, around 20 T, to re-focus the secondary particles generated at the target, introducing complex magnetohydrodynamic (MHD) effects in the liquid metal flow. These effects, particularly caused by Lorentz forces and MHD losses, present challenges to achieving stable and efficient high-power target systems. This work presents multiphase MHD simulations that reveal flow instabilities and highlight potential concerns within the free-falling curtain concept. The findings provide critical insights into the feasibility of liquid lead targets for high-intensity beams.
Paper: THPB017
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB017
About: Received: 26 May 2025 — Revised: 31 May 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
THPB018
Conceptual design and optimization of a liquid lead circuit as beamstrahlung absorber for the CERN’s FCC
2497
Beamstrahlung radiation represents a new challenge at CERN's lepton Future Circular Collider (FCC-ee), specifically for electron-positron collisions. At each interaction point, its unprecedented beam intensities give rise to two photon beams with a power of several hundred kW each. Liquid lead, known for its high density and Z and relatively low melting point, is proposed as a beam dump material to safely dispose of this power. Achieving the necessary effective interaction thickness of 10 to 20 cm presents challenges in optimizing both mass flow rates and the geometric configuration of the lead. This study employs the Monte Carlo code FLUKA to simulate energy deposition and thermal simulations to investigate multiphase flow dynamics within an open-channel configuration. Various slope designs for a free-flowing liquid lead stream within an argon-filled vessel are explored to prevent oxidation. By optimizing the slope and shape of the lead flow, this work seeks to enhance energy absorption and thermal management, improving the effectiveness of liquid lead in high-power beam dump applications.
Paper: THPB018
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB018
About: Received: 26 May 2025 — Revised: 31 May 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
THPB060
Mechanical design and challenges of the FCCee arc radiation shielding
2588
The FCC-ee faces challenges in managing radiation from primary synchrotron photons, which can damage machine components and tunnel equipment due to cumulative exposure. Effective shielding is crucial to reduce equipment failure, prevent performance degradation, and limit reliance on costly radiation-hard materials. The proposed solution involves enclosing photon stoppers with shielding inserts and plates. With 2580 dipoles, each containing 10 photon stoppers, the machine requires shielding for 25800 stoppers. A preliminary lead-based design shows promise in dose reduction, but optimization is needed to control costs, meet integration constraints, and ensure manufacturing feasibility. Current estimates suggest each stopper will require 400 kg of shielding, totaling 10320 tons of lead. Optimization focuses on refining the shielding’s shape, size, and materials, while simplifying fabrication and installation to improve scalability. Goals include detailed cost estimates, spatial assessments, and a design addressing thermal management, mechanical integrity, and structural support, ensuring significant reduction of ionizing dose. This work is vital for proving the FCC’s feasibility.
Paper: THPB060
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB060
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
THPB079
Investigation of properties of CuZr alloy for vacuum chamber structural materials
2594
CuZr alloy is considered for the structural material of the vacuum chamber of the Hefei Advanced Light Facility (HALF) storage ring. We tested the outgassing rate of CuZr material. The outgassing rate of CuZr alloy can reach 4.93×10^-11 Pa·L/s·cm² after baking at 180°C for 48h, which is more than one order of magnitude lower than that of SS. These results indicate that CuZr alloy is easier to degas by baking at lower temperatures and is a material with very low outgassing rates. At the same time, it is a highly competitive structural material for future accelerator vacuum chamber based on its good electrical conductivity, high strength and hardness.
Paper: THPB079
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB079
About: Received: 17 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 06 Jun 2025
THPM038
Measurement of the radiation damping time via optical methods
2716
The radiation damping time is a crucial parameter that depends on the overall magnetic structure of the accelerator. Accurate measurement of this damping time can provide insights into the fidelity of the accelerator model by allowing for a comparison with calculated damping time values. In this study, we present a series of measurements of radiation damping times at the VEPP-4M and VEPP-2000 collider at BINP. In order to determine the damping time, we recorded the transverse beam profile using a digital camera. The results includes study of the damping times at revolution frequencies and different energies of the beams.
Paper: THPM038
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM038
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
THPS012
Interaction point beam offset tolerances for luminosity performance at FCC-ee
2922
To achieve physics performance at the Future Circular electron-positron Collider (FCC-ee), luminosity and beam lifetime must be maintained at close to design specifications. Alongside global feedbacks, a fast feedback system is proposed to mitigate beam offset errors at the interaction points (IP), caused by magnet vibrations or other time-varying errors. In this paper, the FCC-ee luminosity performance is simulated for beam-beam interactions including beam offsets, providing performance requirements for the fast feedback system.
Paper: THPS012
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS012
About: Received: 26 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
THPS027
Availability assurance in the future circular electron-positron collider (FCC-ee)
2968
The Future Circular Electron-Positron Collider (FCC-ee) is CERN’s leading proposal for the next generation of energy-frontier particle accelerators. At 91 km long, it is ambitious in size, complexity and technical objectives. Availability is a main challenge. This paper presents results from a Monte Carlo simulation that extrapolates reliability and maintain-ability from systems in current working accelerators to the FCC-ee. Significant integrated luminosity shortfall appears in all energy modes due to low availability and operational efficiency. The primary contributors are highlighted, exposing several compelling R&D opportunities.
Paper: THPS027
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS027
About: Received: 26 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 06 Jun 2025
THPS072
Real-time luminosity optimization in collider experiments using reinforcement learning
3061
This study presents the development and implementation of a reinforcement learning-based algorithm for real-time luminosity tuning in collider experiments. The algorithm is initially pretrained on historical collider data and subsequently fine-tuned online during experiments. By analyzing accelerator measurements collected over several seconds, the model adjusts the magnetic structure to stabilize luminosity under varying experimental conditions. The proposed method allows for adaptive optimization without operator involvement, improving operational efficiency and stability. Results from its application on the VEPP-4M collider are presented, showcasing the method's feasibility and offering insights for its future development and application in accelerator systems.
Paper: THPS072
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS072
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
FRZD3
Highlights from Future Circular Collider Feasibility Study and Path to Construction
3208
The proposed Future Circular Collider (FCC) integrated programme consists of two stages: an electron–positron collider serving as a Higgs-boson, electroweak and top-quark factory,followed by a proton–proton collider operating at a collision energy around 100 TeV. In 2021, in response to the 2020 update of the European Strategy for Particle Physics, the CERN Council initiated the FCC Feasibility Study. This study covered, inter alia, physics objectives and potential, geology, civil engineering, technical infrastructure, territorial implementation, environmental aspects, R&D needs for the accelerators and detectors, socio-economic benefits, and cost. The FCC Feasibility Study was completed on 31 March 2025. We present a few key results along with accelerator R&D goals and discuss the next steps.
Paper: FRZD3
DOI: reference for this paper: 10.18429/JACoW-IPAC25-FRZD3
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025