MOPM
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Monday Poster Session: MOPM
02 Jun 2025, 16:00 -
18:00
MOPM001
RHIC Au operation in Run24
257
The Relativistic Heavy Ion Collider (RHIC) Run 24 was 27 weeks, operating with collisions at the STAR and sPHENIX detectors. The secondary running mode was gold at 100 GeV/u, where there was 3 weeks of operation. The goals of this run were to: reach an intensity of 1.8e9 ions/bunch and fully commission the 56 MHz cavity, ensure sPHENIX systems are ready for Run25,and deliver 1-2e9 minimum bias events for STAR. Beam was delayed 1 week due to two simultaneous failures of essential kicker systems: an AGS extraction bump power supply, and the yellow RHIC abort kicker. Elevated backgrounds at sPHENIX’s MAPS-based VerTeX (MVTX) detector required extensive studies and diagnostics. With a combination of local steering at sPHENIX and a large amplitude bump in the sector 10 and 12 arcs, the background levels with 12 bunches were reduced by a factor of 18. STAR was able to collect over 1.5e9 minimum bias events and the 56 MHz cavity was operated near its full voltage at 700 kV with 1.3e9 ions/bunch. This paper provides a summary of the run and details of the background studies.
Paper: MOPM001
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM001
About: Received: 29 May 2025 — Revised: 31 May 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
MOPM005
Refining dynamic aperture calculations for highly damped accelerators: methods and applications to the FCC-ee
263
The dynamic aperture is a key metric for assessing the stable phase space of particle accelerators and evaluating their overall stability. However, in highly damped accelerators such as high-energy electron synchrotrons like the Future Circular Collider (FCC-ee), the rapid amplitude variation of tracked particles over a few turns introduces significant sensitivity to initial conditions and the particle's starting location. This work investigates these dependencies in the context of the FCC-ee and highlights their implications for stability analyses. We propose novel, more reliable methods to compute the dynamic aperture that account for these effects, improving the accuracy of stability predictions. First results from the application of these methods to the FCC-ee are presented, demonstrating their potential for advancing the understanding of beam dynamics in next-generation accelerators.
Paper: MOPM005
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM005
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
MOPM008
Towards a High Luminosity LHC with even higher performance
271
The High Luminosity LHC (HL-LHC) project aims to increase the integrated luminosity of CERN’s Large Hadron Collider (LHC) over its exploitation era up to the end of 2041 by an order of magnitude compared to the initial LHC design value. This requires doubling the bunch intensity along with several other important changes to the LHC configuration. Dedicated beam experiments in the LHC and its injectors have already demonstrated the feasibility of reaching many of the HL-LHC project design parameters, and simulations show that some parameters could be pushed to further increase the integrated luminosity or used as mitigation measures against potential shortcomings. This paper presents a review of the latest experimental results and the possible reach of the final HL-LHC parameters.
Paper: MOPM008
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM008
About: Received: 28 May 2025 — Revised: 04 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
MOPM012
Parameter and luminosity scenarios for FCC-hh
287
In preparation for the 2026 Update of the European Strategy for Particle Physics, various options are being proposed for a future circular hadron collider, FCC-hh. Here, we discuss a few operational scenarios spanning c.m. energies from about 70-120 TeV, which correspond to the arc dipole field strengths ranging from 12 to 20 T. We present the respective integrated luminosity forecasts, considering a proton beam current similar to the one of the existing LHC (0.5 A) or the upcoming HL-LHC (1.1 A), and limiting the total synchrotron radiation power to at most 5 MW. Additional constraints are imposed on the beam-beam tune shift and the maximum event pile-up.on the maximum event pile up.
Paper: MOPM012
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM012
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
MOPM013
Modelling resonant depolarisation
291
For the FCC-ee collider it is planned to, in regular intervals (minutes), measure the average beam energy of the circulating electron and positron beams with a relative precision of $10^{-6}$ or better, using the method of resonant depolarisation with pre-polarized pilot bunches. In this article, we study basic systematic effects and ultimate uncertainties that may arise in this kind of measurement. To do so, we carry out simulations for a simple model representing an ideal situation, where an ensemble of particles with energy spread is subjected to synchrotron oscillations and to perfect spin motion. We assume an initial spin orientation in the vertical direction for all particles. The behavior of the spin is explored as an exciter frequency is swept slowly or rapidly, and in either direction,through the spin resonance.
Paper: MOPM013
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM013
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM014
Overview of power deposition profiles in the LHC off-momentum cleaning section in Run 3
295
Off-momentum losses at the start of the LHC acceleration ramp in proton runs gave rise to multiple beam dumps by exceeding Beam Loss Monitor (BLM) thresholds in the momentum cleaning insertion (IR3). Accurately estimating the power deposition profiles in IR3 is necessary to determine where BLM thresholds can be optimized, thereby reducing unnecessary beam dumps and improving machine availability and performance. Understanding the loss limits in IR3 is crucial for future High-Luminosity LHC (HL-LHC) performance. In this study, we present FLUKA power deposition results and introduce a newly developed simulation model for BLM benchmarking in IR3. We provide a comprehensive overview of the power deposition in magnets and collimators, identifying potential bottlenecks in the system. Our simulations were benchmarked against multiple fills from 2023 and 2024 that led to beam dumps. The obtained results provide a deeper understanding of the IR3 collimation performance in view of HL-LHC operation in IR3.
Paper: MOPM014
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM014
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM015
Optimizing cavity detuning at high beam intensities in the LHC
299
The increased beam intensity during the high lumionsity LHC era is expected to impose tight margins on the operation of the LHC RF system. The larger momentum spread from the injectors together with twice the bunch charge requires a higher RF voltage at injection to avoid beam losses. However, the peak RF power due to the increased beam loading must be kept below the saturation level of the klystrons. Accurate optimization of RF parameters is therefore needed to maintain a sufficient RF voltage to capture and retain the injected beam. In the LHC, the beam-loading is partially compensated by detuning the RF cavities. This is achieved at injection by a pre-detuning scheme and throughout the injection plateau by applying half-detuning. During the 2024 run the pre-detuning was adjusted with beam to minimize the required peak power at injection. Furthermore, a new algorithm was developed to optimize the setup of the half-detuning scheme at a given bunch intensity. Both measures have been essential to accommodate higher beam intensities in the LHC.
Paper: MOPM015
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM015
About: Received: 27 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM016
Comparison of BCMS and standard beams at LHC injection energy
303
During the Large Hadron Collider (LHC) run in 2024 two beam types were used for physics production with protons. A key difference between the standard 25 ns and the batch compression merging and splitting (BCMS) beams at injection into the LHC, is the smaller transverse emittance achieved with the latter in the injector chain. Despite both beam types appearing indistinguishable in the longitudinal plane, the BCMS beam caused significantly higher beam losses at the start of the acceleration ramp. For the High-Luminosity LHC (HL-LHC) era, start-of-ramp losses could a limitation due to a lack of RF power. It is therefore important to understand the origin of the increase, as both beam types may be used for operational runs after the HL-LHC upgrade. Systematic analysis of the emittance evolution in all three planes have been conducted to investigate the contribution from loss mechanisms like intra-beam scattering (IBS) and RF background noise. Furthermore, estimates of the beam population outside the bunches and start-of-ramp losses are provided to understand the differences in the off-momentum population before the ramp.
Paper: MOPM016
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM016
About: Received: 26 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 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
MOPM018
Energy sensitivity of the High Luminosity LHC optics at the end of the Beta* squeeze
311
During 2022 and 2023 LHC optics commissioning, it was observed that at low-beta* small changes in the beam-energy could generate substantial perturbations of the linear beam optics, requiring re-commissioning of local corrections in the experimental insertions. This issue may become even more significant at the very low beta* anticipated for operation in the High Luminosity LHC (HL-LHC). Furthermore, energy drifts, for example due to the terrestrial tides, have generally been ignored during LHC optics commissioning, with no regular corrections applied during the duration of a specific measurement campaign. This paper examines the anticipated sensitivity of HL-LHC optics corrections to energy errors at end of the beta* squeeze.
Paper: MOPM018
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM018
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
MOPM019
Correction of Long-Range Beam-Beam Driven Normal Sextupolar Resonance Driving Terms
315
Beam-based studies at the LHC injection energy showed that compensation of the strongly driven sextupolar resonance, Qx+2Qy, improved both the dynamic aperture and lifetime of the beam, even when far from the working point and on the far side of the 3Qy resonance. Thus, a reduction of other strong normal sextupolar resonance sources was of interest. In 2024, the first measurements of resonance driving terms with long-range beam-beam (LRBB) interactions were performed. These showed that LRBB was driving the same Qx+2Qy resonance strongly when colliding, in agreement with model predictions. A correction was found for the strongest normal sextupole resonances using the existing sextupole corrector magnets in the LHC, obeying the constraints on the chromatic coupling and the maximum magnet powering. Beam-based tests to validate the response of this correction with non-colliding beams have been performed along with the testing of the LRBB resonance correction during LHC commissioning.
Paper: MOPM019
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM019
About: Received: 23 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM020
Investigation of octupolar resonances in the LHC
319
During operation for luminosity production, the LHC runs with very strong Landau octupoles to ensure the collective stability of the beams. A disadvantage of this is that these octupoles can drive resonances which can be detrimental to beam lifetime. Recently, a special optics configuration has been utilised to reduce the impact of the main octupoles on lifetime. This design relies on correctly modelling the resonance driving term (RDT) response to changes in these magnetic circuits. This paper presents beam-based studies comparing the RDT response to simulations where large discrepancies were found. To try and understand the source of this, several approaches were taken. Various methods including individual circuit measurements, studies of other circuits, and tests at different energy were employed but it remained challenging to localise the source of the discrepancy around the ring. This paper presents an attempt to apply and extend a segment-by-segment method, that has been very effective at identifying local linear optics errors, to non-linear errors through analysis of RDTs.
Paper: MOPM020
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM020
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 01 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
MOPM022
Criticality of powering failure of the main bend circuits in the FCC-ee at the Z-pole energy
327
The electron-positron Future Circular Collider (FCCee) will have a first phase of operation at the Z-pole energy of 45.6 GeV. To reach the target luminosity, a total of 11200 bunches with $2.14 \times 10^{11}$ charges will be used, accounting for a stored energy of 17.5 MJ per beam. Given the small beam emittances, the beam energy density in turn reaches extremely high values. The potential to induce severe damage to the accelerator components must be carefully evaluated for different failure scenarii. The effects of a powering failure of one of the main dipole circuits are described and discussed. The time-dependent effects are simulated with the XSuite tracking code. The results, expressed in term of orbit shifts, optics changes and particle losses, show that this failure is highly critical. The fastest scenario in which the beam experiences a horizontal orbit excursion of 11$\sigma$ in three turns is analysed in detail. Interlocking and mitigation strategies have been evaluated and are discussed.
Paper: MOPM022
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM022
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM023
Damage potential and machine protection criticality of the FCC-ee beams
331
The lepton beams of the Future Circular Collider FCC-ee will store 17.5 MJ of energy per beam during Z mode operation. The damage potential of these beams is an essential input for the design of the machine protection system. In this paper, first, the stored energy and energy density of the FCC-ee beams are reported and compared with the values for the Large Hadron Collider (LHC) and the High-Luminosity LHC (HL-LHC). Then, results of energy deposition studies using FLUKA for the generic scenario of a direct beam impact on graphite are presented. Due to the small beam sizes and the distinct shower development, the FCC-ee beams cause peak energy depositions that for Z mode intensities can be comparable to the LHC proton beams. In a last step, the initial hydrodynamic response of the material is simulated using ANSYS Autodyn for a round beam featuring an equivalent peak energy deposition. The calculated temperature rise and density depletion are presented and discussed.
Paper: MOPM023
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM023
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 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
MOPM025
Advancing the feasibility study of the ALICE fixed-target experiment using crystal-assisted halo splitting with HL-LHC lead ion beams
339
The Large Hadron Collider (LHC) at CERN is the world’s most powerful particle accelerator, capable of colliding proton and lead ion beams at energies up to 7 ZTeV. ALICE, one of the LHC’s key experiments, is designed for studying heavy-ion collisions. A proposed fixed-target experiment within ALICE involves directing a portion of the beam halo, extracted using a bent crystal, onto an internal target positioned a few meters upstream of the detector. For proton beams, this configuration has already demonstrated effective particle flux delivery to the target while operating safely alongside standard beam-beam collisions. However, with lead ion beams, the beam halo comprises nuclei of varying charge, mass, and magnetic rigidity, posing additional operational challenges. This paper presents an analysis of the expected performance, based on multi-turn particle tracking simulations using a detailed LHC model.
Paper: MOPM025
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM025
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 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
MOPM030
Impact of collective effects on beam stability in the FCC-ee main rings and the high-energy booster
359
The electron positron Future Circular Collider (FCC-ee) is considered the primary contender for the next major particle accelerator within the European Strategy for particle physics, aiming to achieve unprecedented luminosities to enable precise measurements of Z, W, and H bosons along with the top quark. Despite its potential, the FCC-ee project faces significant operational and design challenges, especially in managing collective effects such as space charge, wake fields, coherent synchrotron radiation, intra-beam scattering, and beam-beam interactions. The FCC-IS Feasibility Study brings together experts to address these challenges under one umbrella. This paper presents an updated status of the collective effects studies for FCC-ee main ring and high-energy booster, examining their implications and exploring potential mitigation strategies to prevent resulting instabilities.
Paper: MOPM030
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM030
About: Received: 29 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM031
Tapering schemes for FCCee
363
The electron-positron Future Circular Collider (FCC-ee) is designed to operate at four beam energies, from 45.6 GeV to 182.5 GeV. At such energy levels, the circulating beam loses a significant fraction of its energy via synchrotron radiation. As a single RF insertion is foreseen in the ring, large closed-orbit shifts featuring a typical sawtooth pattern and optics distortions are induced. This in turn leads to a significant reduction of the dynamic aperture if no mitigation is implemented. The solution is to adapt the fields of the magnets to the local beam energy which is referred to as "tapering". For practical reasons, this field adjustment must be realized for groups of magnets to limit the number of powering circuits. An algorithm has bean established to self-consistently compute the tapering strengths of a given scheme, the RF phase required to compensate the energy loss and the required orbit corrections. Tapering scenarios, from coarse schemes to fine grained options are studied with the XSuite tracking code in terms of closed-orbit excursion and optics distortion. The results at the Z-pole (45.6 GeV) and $t\bar t$ (182.5 GeV) energies are discussed in detail.
Paper: MOPM031
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM031
About: Received: 28 May 2025 — Revised: 05 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
MOPM035
Comparison of Xsuite simulations with measured backgrounds at SuperKEKB
379
Xsuite is a collection of packages developed to simulate beam dynamics in particle accelerators. It includes Python modules (Xobjects, Xpart, Xtrack, Xcoll, Xfields, Xdeps) that can be seamlessly integrated with one another and with both accelerator-specific and general-purpose Python tools, enabling the study of complex simulation scenarios. The Xcoll module, developed for collimation studies, allows the integration of beam-matter interaction simulations in the tracking through different available scattering models, including those in the BDSIM/Geant4 toolkit. Originally developed for the Future Circular e+e- Collider (FCC-ee) collimation simulation needs, the Xsuite-BDSIM/Geant4 interface is now deployed in full production for FCC-ee collimation studies. A key aspect of such studies relying on complex simulations is their benchmarking against measured data. This paper presents a first comparison of Xsuite collimation simulation results with measured data at the SuperKEKB e+e- collider.
Paper: MOPM035
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM035
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 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
MOPM037
FCC-ee optics tuning studies with pyAT and Xsuite
387
The FCC-ee is a future high-luminosity circular electron-positron collider aiming at achieving unprecedented luminosities with beam energies ranging from 45.6 up to 182.5 GeV. FCC-ee demands precise optics tuning to achieve its ambitious performance goals. This study investigates the tuning and correction of FCC-ee optics under simulated magnet misalignments, with a particular focus on the stringent initial alignment tolerances required in the Interaction Region (IR). Random misalignment errors were introduced, and correction algorithms were applied to recover the nominal lattice configuration using the pyAT optics framework. Post-correction dynamic aperture studies were conducted to assess the stability and resilience of the lattice under realistic operational scenarios. Benchmarking pyAT outcomes against the Xsuite framework validated the reliability and consistency of the corrections. The study offers valuable insights into alignment tolerance limits, correction methodologies, and their implications for beam dynamics, providing essential guidance for the development and operation of the FCC-ee.
Paper: MOPM037
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM037
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM038
FCC-ee Interaction point optics correction with alignment errors using local tuning knobs
391
Optics tuning and correction in the Interaction Point (IP) region of the FCC-ee is critical for achieving the target luminosity. By utilizing dedicated IP tuning knobs, lattice errors at multiple IP's are corrected to restore the design optics, enabling dynamic aperture studies on the fully corrected lattice. These studies, conducted using the pyAT optics code, assess the impact of corrections and the effectiveness of various tuning knobs in mitigating beam size growth at the IP's while maintaining beam stability. Benchmarking of pyAT results with the Xsuite framework ensures the reliability and robustness of the analysis. This approach provides valuable insights into the precision of IP optics tuning and its role in optimizing the collider's operational performance.
Paper: MOPM038
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM038
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 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
MOPM045
A numerical study on injection efficiency improvement at SuperKEKB electron ring
415
SuperKEKB is an asymmetric lepton collider with 7-GeV electron and 4-GeV positron beams. The current vertical beta function (βy) at the collision point is set to 1 mm. Experimental results confirm that reducing βy leads to narrower dynamic apertures in both the horizontal and vertical directions, which in turn decreases the beam injection efficiency. This study presents a numerical investigation aimed at improving injection efficiency to achieve higher beam luminosity.
Paper: MOPM045
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM045
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
MOPM046
Generation of GeV-range photons via Inverse compton scattering at the FCC-ee
418
This study explores the feasibility of generating high-energy photons, reaching up to 150 GeV, at the FCC-ee booster through inverse Compton scattering. The proposed scheme utilizes a laser within a Fabry-Perot cavity, enabling high repetition rates while minimizing recoil effects during individual collisions. This approach supports the potential use of the FCC-ee booster as a high-energy light source. The photon spectrum and energy distribution are analyzed, with simulation results presented for electron-laser interactions within the Fabry-Perot cavity.
Paper: MOPM046
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM046
About: Received: 23 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 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
MOPM049
Longitudinal wakefield implementation in the circulant matrix model
430
The influence of longitudinal wakefields on the beam dynamics in electron-positron colliders, particularly their role in beam instabilities such as Transverse Mode Coupling Instability (TMCI) and other transverse-longitudinal effects, necessitates a robust approach to accurately model these effects. This work focuses on the implementation of wakefield effects in the Circulant Matrix Model (CMM), a linear model that can facilitate the representation of these instabilities. We study the impact of potential well distortion and synchrotron frequency shifts due to longitudinal wakefields for FCC-ee and implement these effects in the CMM. The implementation is benchmarked against reference multiparticle tracking simulations to validate its accuracy in predicting longitudinal wakefield-driven instabilities. Results enable further studies featuring longitudinal wakefields for collider designs and operating machines.
Paper: MOPM049
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM049
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM050
Combining quadrupole-driven slow extraction with RFKO at the CERN SPS
434
The CERN Super Proton Synchrotron (SPS) employs quadrupole-driven third-integer slow extraction to deliver beam to the North Area. This process is controlled by ramping all the magnets in the lattice, gradually driving the circulating beam into the tune resonance. In medical synchrotrons, Radio-Frequency Knock Out (RFKO) has proven to be a reliable alternative for driving the extraction process while maintaining good spill quality. Inspired by these efforts, a hybrid scheme was tested in the SPS, where a transverse exciter was used to apply a sinusoidal excitation in parallel with the magnetic ramp. It is demonstrated that this setup improves spill uniformity both in simulation and measurements.
Paper: MOPM050
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM050
About: Received: 26 May 2025 — Revised: 30 May 2025 — Accepted: 01 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
MOPM052
Bayesian methods and differentiable models for optics studies at the ISOLDE facility
442
The Isotope mass Separator On-Line facility (ISOLDE) delivers a wide range of low-energy radioactive ion beams to its experimental users. To meet varying demands, the facility uses different target materials, ionization methods, and cooling/bunching techniques, with beam configurations potentially changing weekly. To model particle transport through the transfer lines, it is essential to reconstruct the beam's initial transverse phase space for each setup, achieved via quadrupole scan measurements. This work explores the application of Bayesian techniques and differentiable models to reduce the time required to perform the beam setup.
Paper: MOPM052
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM052
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
Proposal of Z pole electron-positron ERL colliders
Electron-positron ERL colliders at the Z pole are proposed as a sustainability near future collider.The components are similar to the ILC accelerator, which consists of the linac with the 9 cell superconducting cavities, the 5 GeV damping ring, the beam delivery system for the final focus, and the electron and positron injectors. The recirculation loop is added to the ERL scheme. To fit it in the Tsukuba campus site of KEK, the accelerating gradient should be the same as the ILC of 30 MV/m, which can be achieved at 1 us RF pulse operation. Therefore, the energy recovery is imperfect because the return beam is delayed by the circulation time. In this presentation, we show the schematic views.
Optics studies at the compact ERL
The compact ERL has been operated at the various beam optics as a test facility for industrial applications, such as the future EUV-FEL for a lithography. The short bunch length is the key for the high intensity SASE FEL therefore a tunable R56 of the arc optics is necessary for the bunch compression. We demonstrate the two kinds of arc optics: one is easy optics matching and another one is having a large energy acceptance. In addition, the deflector cavity is installed downstream of the undulators for the bunch length measurement. The beam optics is optimized for high resolution measurement. In this presentation, we show the summary of the optics tuning and the results.
MOPM058
Beam tracking simulation of the capture LINAC for the ILC e-driven positron source
446
In the electron-driven positron source of the International Linear Collider (ILC), positrons are generated through electromagnetic showers by irradiating a target with a 3 GeV electron beam and then accelerated in a positron capture linac in a solenoid magnetic field. Because of the high current multi-bunch beam requirements of ILC, the beam loading effect is one of the important issues. In order to identify engineering issues, a test bench has been set up at the KEK-STF to build and test prototypes of a target system, a flux concentrator, an accelerating tube and a solenoid coil. Based on this test bench arrangement, a beam tracking simulation of the positron source from target to the upstream of the capture linac has been started by PIC simulation using the commercial code CST studio. In this contribution, the results of beam tracking simulation with the realistic magnetic field, accelerating field and placements of components and the effects of beam loading on beam energy and yield will be reported.
Paper: MOPM058
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM058
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 06 Jun 2025
MOPM060
CETASim: a numerical tool for beam collective effect study in storage rings
449
We developed a 6D multi-particle tracking program CETASim in C++ to simulate intensity-dependent effects in electron storage rings. The program can simulate the beam collective effects due to short-range/long-range wakefields for single/coupled-bunch instability studies. It also features the simulation of interactions among charged ions and the trains of electron bunches, including both fast ion and ion trapping effects. The bunch-by-bunch feedback is also included so that the user can simulate the damping of the unstable motion when its growth rate is faster than the radiation damping rate. The particle dynamics is based on the transfer maps from sector to sector, including the nonlinear effects of amplitude-dependent tune shift, high-order chromaticity, and second-order momentum compaction factor. Users can also introduce a skew quadrupole useful for emittance sharing and exchange studies. This paper briefly introduces the code structure and gives benchmark studies for single and coupled bunch effects. PETRA-IV H6BA lattice parameters are applied as test-bed.
Paper: MOPM060
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM060
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM061
Study of single bunch effect in PETRA-IV storage ring
452
The H6BA lattice is now considered as the baseline design for PETRA-IV light source. It is required that the ring can be operated with and without damping wigglers, resulting in two sets of natural equilibrium beam parameters. This paper analyzes the single-bunch effects due to impedance in the H6BA lattice of PETRA-IV. We will show the influence of the impedance on the electron beam in both scenarios, with and without DWs. With the help of a 3rd harmonic cavity and a high chromaticity of 6 units, the single bunch current threshold exceeds 2 mA, leaving a 100% safety margin. At the nominal coupling of 0.1, the Touschek lifetime is larger than 10 hours in all operational scenarios.
Paper: MOPM061
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM061
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM063
Collimator damage study for the Diamond-II storage ring
455
To understand the risk of damage to the collimator blades and the permanent magnets in Diamond-II, the BDSIM code has been used to model the beam losses. To improve the accuracy, the engineering model and 3D field maps have been used to build the machine model. Energy deposition in the main storage ring components and the fluence of secondary particles (particularly neutrons) have been determined. This paper explains the simulation process and give the BDSIM tracking results.
Paper: MOPM063
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM063
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM064
Operational experience and design improvement studies of the LHC MKI cool
459
In view of the unprecedented beam intensities expected in the High-Luminosity era of the Large Hadron Collider (HL-LHC), an upgrade of the LHC injection kickers (MKIs) is currently underway. This upgrade aims to mitigate excessive beam-induced heating of the MKIs and to limit resulting vacuum activity. The first MKI Cool was installed in the LHC during the Year End Technical Stop (YETS) in 2022-2023, and the upgrade of the entire system of 8 injection kickers is expected to be completed during Long Shutdown 3 (LS3). This paper discusses the operational performance of the new MKI Cool magnets and compares it to the magnets of the post-LS1 design. Additionally, it focuses on investigations aimed at understanding the observed results, with the goal of further enhancing the performance of the MKI Cool design.
Paper: MOPM064
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM064
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
MOPM065
Feasibility of kicker systems for FCC-ee and injectors
463
CERN’s Future Circular Collider (FCC) comprises a ~91 km circumference lepton collider and its injector complex. This contribution summarises the feasibility studies performed for the various kicker systems needed to transfer the beam between the different machines. The individual system requirements are reviewed, recent changes are highlighted, and the chosen conceptual design is outlined. Particular effort has been made to harmonise the hardware parameters across the machines to minimise the number of different beam line element types. The feasibility of the design parameters and technology options is discussed for both beam line elements and pulse generators. Early system integration aspects and implications on subsystems such as pulse transmission cables are also discussed. Consequences of the more restrictive requirements on the abort gap length in the collider are analysed. This contribution concludes with recommendations for detailed studies and prototyping required to ensure a viable parameter space for the upcoming detailed technical design phase.
Paper: MOPM065
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM065
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
MOPM066
Performance improvement studies for the CERN SPS MKDH system
467
The CERN-SPS beam dump system (SBDS) is equipped with a dilution kicker system, the so-called MKDH. During the 2022 and 2023 beam commissioning, the vacuum rise in the MKDH became a concern for reaching the anticipated higher beam intensities. Dedicated conditioning of the SPS kickers enabled successful attainment of High-Luminosity (HL) beam intensities during 2024 operation. However, the conditioning time required after replacing an MKDH magnet remains a significant concern, leading to a study aimed at optimizing its high intensity performance. This paper presents a feasibility assessment, a detailed characterization of the operational kickers and the spare units, and proposed modifications designed to optimize the MKDH kicker magnet performance. The modifications focus on minimizing interactions and coupling between the kicker and the beam, with the ultimate goal of improving the operational efficiency with high intensity beams.
Paper: MOPM066
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM066
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 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
FCC-ee radiation environment and shielding
The secondary radiation fields generated by synchrotron photons pose a significant challenge for equipment in high energy electron and positron storage rings like the Future Circular Collider (FCC-ee) at CERN. The annual ionizing dose can reach MGy-levels in the FCC-ee tunnel and requires the design of a dedicated radiation shielding enclosing the photon stoppers in dipoles. In this paper, we present a first optimization of the shielding design, taking into account different aspects such as shielding efficiency, engineering and integration constraints, raw material costs, and radiological considerations. We demonstrate that the proposed shielding solution can decrease the dose in the tunnel by about two orders of magnitude, which considerably reduces the need of expensive radiation-hard equipment. In addition, we explore the option of housing accelerator electronics in a dedicated bunker near lattice quadrupoles, which can possibly allow for custom-off-the-shelf-based radiation tolerant electronics systems. We quantify the expected radiation levels in this bunker, which are driven by photo-neutron production by the high-energy component of the synchrotron spectrum.
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
MOPM071
Dual-purpose structure for light and heavy particles
479
A dual-purpose structure has been developed for the NICA collider accelerating heavy multiply charged ions and light polarized nuclei of protons and deuterons. For heavy multiply charged ions, it is necessary to solve the problem of intrabeam scattering, which requires minimal modulation of the envelope and dispersion function. For light particles, the problem of crossing transition energy arises. In the proposed structure, both problems are solved due to a specially developed structure of magnetic arcs. This magneto-optical structure can be used to accelerate both heavy ions and light polarized protons and deuterons without loss of beam quality.
Paper: MOPM071
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM071
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 06 Jun 2025
MOPM072
Status of the DELTA synchrotron light source
483
DELTA, a 1.5-GeV electron storage ring facility operated by TU Dortmund University in Germany, celebrated its 30th anniversary in fall 2024. During its time in operation, the facility has been continuously developed to provide synchrotron radiation (SR) users with the most reliable and attractive radiation source possible. This includes continuous improvements of electron beam stability and lifetime, the installation of a new 7-T superconducting wiggler magnet with a specially adapted SR outlet chamber, as well as the integration of a second solid-state amplifier-driven radiofrequency system. In recent years, there have also been many exciting developments in the field of accelerator physics. These include the construction of a facility for generating ultrashort and coherent SR pulses, studies involving laser-induced terahertz radiation, and experiments conducted in single-electron mode that complemented ongoing research activities. Furthermore, projects focusing on intelligent system control using machine learning methods were successfully implemented. This report summarizes the most significant developments over the past years.
Paper: MOPM072
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM072
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
Longitudinal beam dynamics tracking simulation for the triple radio-frequency system in electron storage rings
For diffraction-limited storage rings, the triple radio-frequency (RF) system has been proposed to achieve further bunch lengthening or to meet specific requirements for longitudinal injection. The choice of RF cavity parameters for the triple RF system has a significant influence on the longitudinal beam dynamics. Macroparticle tracking simulation is commonly used to accurately analyze this influence. In this paper, we extend the STABLE code [1] to study the dynamics of the triple RF system assumed for the Hefei Advanced Light Facility storage ring. It is found that there are two important factors that possibly limit the bunch lengthening.
Cross-talk effect of adjacent impedance elements studied for the HALF storage ring
In the storage ring of a fourth-generation synchrotron light source such as the Hefei Advanced Light Facility (HALF), a multitude of vacuum elements interact with the beam current, thereby generating beam coupling impedance. This is a crucial factor contributing to beam instabilities and affecting the machine performance. Conducting impedance analysis on a vacuum element-by-element basis, without accounting for the cross-talk effect between adjacent elements, may result in an imprecise impedance model. This could subsequently have a detrimental impact on the accuracy of beam dynamics analysis. In this paper, we will utilize CST electromagnetic simulation software to model adjacent impedance elements in the HALF storage ring, with a view to conducting a comprehensive investigation into the cross-talk effect.
Steady-state response matrix of radio-frequency cavity voltage in storage rings
The study of beam-cavity interaction is an essential step towards achieving the design objectives of high-intensity storage rings, particularly in the rapidly advancing fourth generation of synchrotron light sources, which rely on the strategy of bunch lengthening with harmonic cavities. Assessing the effectiveness of harmonic cavities typically requires self-consistently solving bunch equilibrium distributions, accounting for beam-loading voltages. This paper introduces a novel concept of the steady-state response matrix (SSRM) of radio-frequency (RF) cavity voltage: the steady-state beam-loading voltages are expressed as a product of the SSRM and an array containing only the information in bunch charge density distributions. Notably, the SSRM depends solely on RF cavity parameters such as R/Q, loaded Q, and resonant frequency. We demonstrate that the SSRM can significantly simplify and accelerate the self-consistent calculation of bunch equilibrium in double RF systems. Additionally, the SSRM can also facilitate the calculation for transient beam-loading feedforward compensation and the evaluation of thresholds for periodic transient beam-loading effect.
Transposition of the high-current beam transport strategy to new AIRIX functioning points obtained by increasing the diameter of the cathode
Experimental programs entrusted to the Franco-British EPURE facility require more and more flexibility with regard to the operation of different functioning points for our two Linear Induction Accelerators (LIA). In 2023, UPRX work (presented at IPAC'24) demonstrated our ability to control both reliability and repeatability of our first radiographic axis performances at high current (2.6 kA). To do this, a new strategy of electron beam transport based on the beam envelop constraint just downstream the injector module has been adopted, so as we managed to control BBU instabilities. In 2024, by increasing the diameter of the first radiographic axis cathode (from 63.5 to 70mm), we explored different “current/voltage” combinations and have demonstrated that the 2024 transport strategy could be transposed to the new generated beams at both 2.6 and 3kA (and a nominal 3.8 MeV energy at leaving from injector). We consequently proved our capacity to reach higher level of dose and a detailed analysis of the new beam initial conditions has highlighted the advantage of this new cathode, notably in view of optimizing the photonic focal spot size.
MOPM077
Commissioning of the new FLASHlab@PITZ beamline extension
487
Over the past year a new beamline dedicated to R&D for electron FLASH cancer radiation therapy and radiation biology was set up at the Photo Injector Test facility at DESY in Zeuthen (PITZ). The beamline runs in parallel to the SASE THz beamline at PITZ and is connected to it with an achromatic dogleg. The dispersion within the dogleg is utilized to install an aperture to scrape off-energy dark current. The following straight section of the beamline contains a kicker system which will be capable of distributing electron bunches from a single bunch train freely over an area of 25mm x 25mm within one millisecond. So far, only the slow kicker for the vertical plane is installed – the fast kicker for the horizontal plane will be installed soon. Behind an exit window is an experimental area for conducting irradiation experiments with the 22 MeV electron beam, which can accommodate setups for a wide range of experiments. Here we report the completion of the construction of the new beamline with detailed information about the setup. Preparation results of the PITZ robot and further data of the new experimental area are described. Additionally some new simulation results are given.
Paper: MOPM077
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM077
About: Received: 26 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 06 Jun 2025
MOPM078
Automation of pulse identification at J-PARC
491
At J-Parc, the 500 μs long macro-pulses generated by the LINAC are separated into intermediate-pulses to synchronize it to the frequency of the Rapid-Cycling-Synchrotron (RCS). To secure a stable operation, the knowledge of position and length of those intermediate pulses are crucial, as the pulses need to be adjusted to the RCS frequency. The measurement for this adjustment is done by a beam position monitor (BPM), positioned directly behind the LINAC section in the low energy beam transport (LEBT) section. Since the form of the detected pulses can vary, the implementation of classical algorithms for the automatic detection and identification of pulses proofed unreliable. Because of that, it was decided to develop a machine learning algorithm for the automatic pulse identification. In this paper, the background, training and results of different machine learning algorithms developed for the described problem will be introduced and discussed. Additionally, a test of the developed program during active beam operation is being planned, and will be introduced.
Paper: MOPM078
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM078
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
MOPM079
Automated conditioning utilizing machine-learning: first experimental results
495
The conditioning of room temperature cavities is a long process. Additionally, since the cavity or auxiliary equipment can be damaged, constant supervision or extensive safety precautions are required. To reduce the workload for everyone involved and to increase the efficiency of the conditioning process, it was decided to develop a machine learning algorithm with the goal of fully automated conditioning in mind. The initial model was trained on available data of the low energy-domain (up to 500 W). Since it was possible to expand the data to higher power levels during conditionings in 2024, the algorithm is now trained for power levels up to 30 kW. In this paper, the challenges of training with different power scales, as well as the first experimental results shall be discussed.
Paper: MOPM079
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM079
About: Received: 28 May 2025 — Revised: 29 May 2025 — Accepted: 30 May 2025 — Issue date: 06 Jun 2025
MOPM080
Optimisation of drift tube cooling and drift tube geometries of an additive manufacturing IH-type cavity
499
Additive manufacturing is a now-powerful tool for the rapid prototyping and manufacturing of complex geometries. A proof-of-concept 433 MHz IH-DTL cavity was constructed for direct additive manufacturing of linear accelerator components. The CFD analysis of the initially designed cooling for the drift tube revealed a design with insufficient heat dissipation; this can lead to thermal deformations as well as problems in keeping the frequency stable during operation. In this respect, an optimization of the cooling system was done in detail with the help of advanced thermal simulation and iterative design improvements. Furthermore, the geometries of the drift tubes were refined to improve mechanical stability and thermal efficiency without compromising electromagnetic performance. The results illustrate that additive manufacturing can achieve significant design freedom, enabling new approaches toward the thermal management challenges faced by high-frequency linear accelerator components.
Paper: MOPM080
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM080
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM082
Phase space measurements of 90 mA and 52.5 keV H⁻ ion beam at J-PARC frontend
503
A 90-mA and 52.5-keV negative hydrogen ion (H⁻ ion) beam has been extracted from the J-PARC Radio Frequency (RF) H⁻ ion source. The 90-mA beam phase-space distribution at the entrance of the Radio Frequency Quadrupole (RFQ) cavity was measured at the test stand. Compared with the 60-mA beam condition for the present J-PARC user operation, reasonable increase in the operation parameters (the RF input power to the ion source, the electrostatic voltage for beam extraction, and the solenoid currents for Twiss matching with the RFQ) was observed. The normalized RMS emittance increased by a few 10 %, which is within the acceptable range of the RFQ. In addition, the dependence of the beam phase-space distribution was investigated with respect to the operation parameters. Numerical analyses show that the optimum solenoid current was determined to remove the beam halo component with the orifice in the beam transport section, which was originally installed for the differential vacuum pumping of the ion source and the RFQ. In the presentation, the effect between the beam current and the phase-space distribution are discussed in aspect of the H⁻ ion beam optics.
Paper: MOPM082
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM082
About: Received: 28 May 2025 — Revised: 29 May 2025 — Accepted: 30 May 2025 — Issue date: 06 Jun 2025
MOPM083
Status of the FLUTE RF system upgrade
506
FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a new compact versatile linear accelerator at KIT. Its main goal is to serve as a platform for a variety of accelerator studies as well as a generation of strong ultra-short THz pulses for photon science. Also it will be used as an injector for a Very Large Acceptance compact Storage Ring (VLA-cSR) which will be realized at KIT in the framework of the compact STorage Ring for Accelerator Research and Technology (cSTART) project. To achieve acceleration of electrons in the RF photo-injector and linac with high stability, it is necessary to provide stable RF power. For this goal, an upgrade of the existing RF system design has been proposed and is currently being implemented. In this contribution an updated RF system design and the status of the RF photo-injector, linac and bunch compressor commissioning will be reported.
Paper: MOPM083
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM083
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 06 Jun 2025
MOPM084
Development of a step motor system for TPS Linac RF system
509
The linear accelerators of the Taiwan Photon Source has been fully operating for more than 10 years. Considering components’ aging issues and a shortage of supply chain due to phase-out parts, an alternative solution for these components with the same functionality must be prepared in case of need in order to ensure the TPS Linac’s smooth operation. In this report, a new 6-axis step motor controller is built. This controlling system could be used in TPS Linac’s radio frequency (RF) power distribution system and RF phase adjustment. Moreover, this new established system can replace the original one and it can be used as spare components. This report introduces in detail of this controlling system, including motor’s selection, step motor controller and its controlling software.
Paper: MOPM084
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM084
About: Received: 21 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 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
MOPM087
Design of the FCC-ee injector linacs up to 20 GeV beam energy
516
The FCC-ee injector complex aims to deliver tunable, high-charge electrons and positron bunches for injection into a collider operating at center-of-mass energies from 90 to 365 GeV. The injector complex includes multiple linacs that sequentially boost the energy of the bunches to the booster injection energy of 20 GeV. This work addresses the significant challenges posed by the required beam parameters. We designed the electron (up to about 3 GeV) and the high energy (up to 20 GeV) linacs to provide very limited emittance growth due to static imperfections, maximum acceleration efficiency, excellent stability of the beam transverse jitter, and to match the requirements on the bunch length and single- and multi-bunch energy spread as well. An energy compressor system has been foreseen, to provide flexibility to scan beam charges across a wide range without compromising the final energy spread. This paper summarizes the comprehensive design and optimization studies conducted, demonstrating that the proposed linac system meets all current requirements for efficient injection into the booster ring, paving the way for the ambitious operational goals of the FCC-ee accelerator complex.
Paper: MOPM087
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM087
About: Received: 26 May 2025 — Revised: 28 May 2025 — Accepted: 29 May 2025 — Issue date: 06 Jun 2025
RF design of the positron traveling-wave structure
The Super Tau-Charm Facility (STCF) is a new generation of electron-positron colliders being planned with a design center of mass energy of 2-7 GeV. In the concept design, the positrons produced by electron targeting are accelerated to an energy of 200MeV by three large-aperture accelerating structures, and then to 3.5GeV by several conventional accelerating structures. The aperture of large-aperture accelerating structures is maintained constant, and the group speed is controlled solely by adjusting the length of the nose cone for easier production. Pulse compressors are taken into account to increase the accelerating structures power. In this paper, the designs of 2m and 3m large-aperture accelerators are presented, both achieving gradients higher than 15 MV/m.
MOPM089
Solid-state driven X-band linac for microcrystal electron diffraction
520
Transmission Electron Microscopes (TEM) require high voltage DC electron sources, which can quickly grow in size and cost at the higher energies required for standard TEM imaging. We present the progress on a low cost, compact solid-state-driven RF linac to replace high power electron guns in micro-crystal electron diffraction setups. The system accelerates electrons to 50 keV electrons with a 4 cell standing wave structure, where each cell is individually powered by an X-band solid-state amplifier. Future expansions on this design could function as a compact (order of 1 meter) source of electrons up to 1 MeV.
Paper: MOPM089
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM089
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
Magnet R&D for the muon collider: proposed R&D plans
The muon collider represents a transformative approach in particle physics, offering a pathway to achieve high energy and luminosity with reduced environmental impact compared to other collider technologies. Central to its feasibility is the development of advanced magnet systems capable of supporting the stringent requirements of muon production, acceleration, and collision. The key targets for magnet R&D include achieving field levels up to 40 T, magnets with stored energies up to 300 MJ, managing heat loads from muon decay at the level of several W/m, and ensuring radiation resistance well above 50 MGy. Given such extraordinary challenges, research presently focuses on integrating high-temperature superconductors (HTS), tailored for efficient cooling at cryogenic temperature, and striving for compact magnets to reduce the capital expenditure. In the past years we have progressed in the conceptual design, and in some cases initiated engineering design as well as materials and small-size coil testing. This has allowed to outline an R&D plan that we describe in this paper. The proposed plan involves staged milestones which include development of magnet prototypes.
MOPM091
The European Spallation Source neutrino Super Beam project and physics performance
524
The goal of the ESSnuSB project is to precisely measure neutrino Charge-Parity Violation (CPV). The construction of the European Spallation Source, ESS, represents an outstanding opportunity for such project to take place. ESSnuSB has been funded from EU in the framework of H2020 (2018-2022) and Horizon Europe (2023-2026) to make feasibility studies. The aim of the first phase was to demonstrate that the ESS linac can be used to generate an intense neutrino beam, which coupled with a megaton water Cherenkov detector placed in a mine 360 km from ESS, could allow the detection of neutrinos at the 2nd oscillation maximum. A CDR* has been published in which it is shown the unprecedented physics performance to precisely measure CPV. For this, the modification to compress the proton pulse length from 2.86 ms to 1.3 μs has been studied. The second, ongoing Design Study, ESSnuSB+, is devoted to neutrino cross-section measurements relevant to ESSnuSB. Two facilities are proposed, a low energy nuSTORM (muons decaying to neutrinos in a storage ring) and a low energy ENUBET (pions decaying to a muon and a neutrino and monitoring of the neutrino beam by detection of the decay muon).
Paper: MOPM091
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM091
About: Received: 20 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 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
MOPM093
Positron contamination in the muon beam at the J-PARC's surface muon beamline (S-line)
531
The surface muon beamline at J-PARC provides high-intensity muon beams that are essential for advanced materials science research, particularly in techniques such as muon spin rotation/relaxation (μSR). However, positron contamination in the beam poses a significant challenge by introducing background noise that affects the measurement precision. Therefore, achieving high-purity muon beams is critical for improving experimental reliability and accuracy. In this study, the G4beamline Monte Carlo simulation toolkit was employed to model the transport of muons and positrons from the production target through the beamline. The system includes a momentum and charge-based separator followed by a collimating slit. While the current slit configuration effectively suppresses positrons, it also causes substantial muon loss of approximately 76%, which significantly reduces the usable muon flux for downstream applications. To address this issue, a detailed investigation into slit size was performed. The results indicate that modest adjustments to the slit aperture size can improve the muon-to-positron ratio while retaining a greater fraction of the muon beam. These results provide valuable guidance for optimizing beamline performance and improving the quality of muon-based experiments at J-PARC.
Paper: MOPM093
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM093
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
A high-peak-power, phase-stabilized laser system for quasi-steady-state microbunching
Steady-State Microbunching (SSMB) proposes a novel mechanism for generating high-average-power coherent radiation spanning from THz to EUV, with significant potential for various applications. This paper presents the development of a laser system tailored to serve as the modulation laser for the second phase of the SSMB proof-of-principle (PoP) experiments. To verify the stability of microbunching, we have developed a 1064 nm laser system with a burst-mode time structure, achieving peak power exceeding 20 kW. Ensuring the stability of the electron bunches' turn-by-turn phase within the storage ring is crucial for coherent modulation. To address this, we employ an iodine-frequency-stabilized CW seed laser and implement a phase-locking loop. Measurements show that the phase error is below 0.1%π, fulfilling the experimental requirements. The laser system is scheduled for shipment to Berlin, Germany, where it will be integrated with the MLS quasi-synchrotron ring at HZB for the SSMB PoP II experiment.
The mass production magnetic field measurement of the large aperture quadrupoles in HIAF
Currently the HIAF Project at IMP has reached the construction phase. The BRing is one of the key systems of HIAF, which is used to capture, accumulate, accelerate and extract the heavy ion beam injected by iLinac. The quadrupole magnets in BRing have large aperture (Ф260&Ф180) , large axial length(the total length of the magnet is reached 1140mm) and high integration field uniformity (±3×10-4). To measurement the magnetic field quality is very critical. The measurement aims to reach a reproducibility of 1.5×10-4 for the field integral, 2 ppm for the harmonic content for the main field and 0.2mm for the position of the magnetic center. A specially developed probe allows the simultaneous measurement of the field axis and quality. This thesis demonstrates that the system as it stands fulfils the high requirements with respect to the magnetic measurement and the magnetic center and thus provides the desired unique versatile equipment. The assessment was performed based on experimental results, direct calibration. The main defects treated are mechanical torsion and vibration of moving parts, electrical noise and power supply ripple.
MOPM099
Accelerator and Compton gamma-ray source research program at Duke University
534
The accelerator and Compton gamma-ray source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring-based free-electron laser (FEL) and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS) driven by the storage ring FEL. With a maximum total flux of about 3.5E10 gamma/s and a spectral flux of more than 1,000 gamma/s/eV around 10 MeV, the HIGS is the world's highest-flux Compton gamma-ray source. Operated in the energy range from 1 to 120 MeV, the HIGS is a premier Compton gamma-ray facility in the world for a variety of nuclear physics research programs, both fundamental and applied. In this work, we will describe our recent FEL development to enable the production of gamma rays in the higher energy range from 100 and 120 MeV. We will also provide a summary of our recent activities in accelerator and FEL physics research and Compton gamma-ray source development.
Paper: MOPM099
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM099
About: Received: 05 Jun 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM100
Benchmarking the LHC impedance model through loss of Landau damping measurements and simulations
538
Refining the present longitudinal impedance model is essential for an accurate prediction of beam stability thresholds. Longitudinal loss of Landau damping (LLD) for single bunches were observed in the Large Hadron Collider (LHC). For High Luminosity (HL-) LHC beams, the present stability margin is aimed to be maintained. While coupled-bunched instability has not been detected in the LHC so far, it may become an issue at HL-LHC parameters. Recent studies have shown that broad-band impedance contributions and their cut-off frequencies affect the LLD threshold. In this contribution, results from the analysis of the machine development studies of 2024 are presented and compared to macroparticle tracking simulations, as well as LLD threshold predictions using semi-analytical solvers. Their discrepancies are discussed, and potential sources are investigated.
Paper: MOPM100
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM100
About: Received: 16 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 06 Jun 2025
MOPM101
Upgrade of the LHC main RF system for HL-LHC
542
In the era of the High-Luminosity Large Hadron Collider (HL-LHC), the main RF system will be limited in voltage and power on the injection plateau due to strong beam loading. At the same time, significant start-of ramp losses, that are originating from capture and flat bottom losses, are expected and can severely impact machine availability or even prevent the beam from reaching the collision energy. In this contribution, we present the recent experience with high-intensity beams during operation and dedicated measurements to give an update on the estimated RF voltage reach for HL-LHC beam parameters. Projections for beam losses at capture, along the flat bottom, and at the start of the ramp are calculated, taking into account also the effect of intra-beam scattering. We discuss in detail the mitigation measures put in place, such as high-efficiency klystrons, the revision of beam loss monitor thresholds at the start of the ramp, and automatic working point optimization.
Paper: MOPM101
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM101
About: Received: 16 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
MOPM102
Local and global betatron coupling correction based on beam position measurements in RHIC
546
Local coupling correction in Interaction Regions (IRs) and global coupling correction based on Base-Band Tune (BBQ) measurement have been performed routinely for RHIC operation. However, one still observes significant residual local coupling measured by beam position data. For the Electron-Ion Collider (EIC) project, betatron decoupling for the hadron beam needs to be improved to maintain a large horizontal to vertical beam emittance ratio (12:1). In this paper, we will analyze the cause for noticeable residual coupling in RHIC and propose an integrated local and global betatron coupling correction based on beam position measurements. We will also present experimental results from ML-based optimization of the local and global coupling in RHIC.
Paper: MOPM102
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM102
About: Received: 29 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM103
A proposal of a momentum collimator in RHIC warm section for controlling experimental background at sPHENIX
549
One of the issues that the AuAu 100 GeV physics program in 2024 in RHIC encountered was background in the sPHENIX MVTX detector, which causes autorecoveries and preventing continuous data taking. Beam studies and track simulations performed to understand the source of the background and potential measures to control it have led to the conclusion that off-momentum particle loss was an issue. This article will focus on a proposal of a momentum collimator in warm sections in RHIC to control the MVTX background. We will elaborate the selection of the locations for the collimator, the strategy of generating substantial horizontal dispersion there, the required additional powering scheme for selected quads and the optimization of the figure-of-merit for momentum collimation.
Paper: MOPM103
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM103
About: Received: 29 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM107
Status of construction of the new heavy ion synchrotron SIS100 at FAIR
553
The construction of the new FAIR heavy ion accelerator facility at GSI is progressing well. With the start of installation of SIS100 an important new milestone in project execusion has been reached. SIS100 is the first superconducting, fast ramped synchrotron with special design features dedicated to the acceleration of high intensity, low charge state heavy ions. The full performance of the specific functional systems, stabilizing the dynamic vacuum at operation with high Uranium intensities in combination with high repetition rates, was recently demonstrated at the SIS100 string test. Even under the influence of eddy current heating of the chamber walls at high ramp rates, its separatly cooled cryogenic vacuum system assures a stabilization of the residual gas pressure at extremely low values. The first straight sectors and arc modules have been installed heading towards a first hardware commissioning in 2026.
Paper: MOPM107
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM107
About: Received: 01 Jun 2025 — Revised: 03 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
Selected beam dynamics measurements at DAFNE
In 2024 DAFNE successfully completed the data delivery for the SIDDHARTA-2 detector largely exceeding the integrated luminosity requested by the experiment. This has allowed allocating the machine time for several dedicated beam dynamics experiments useful for both the collider characterization and for the design of future electron-positron colliders based on the crab waist collision concept.
Damping ring and transfer lines for FCCee Injector complex
A novel damping ring design and related transfer lines for the FCCee are proposed. The presented damping ring layout is optimized for operation at 2.86 GeV to efficiently cool both electron and positron beams and should cool down the transverse emittance of the positron beams by four orders of magnitude. The system accommodates beam trains consisting of 4 bunches separated by 25 ns, with a repetition rate of 100 Hz. Different layouts, including triangular and hexagonal geometries, have been investigated, utilizing various base arc-cell configurations such as FODO, six-bend achromat, and 10-bend structures. In addition to the damping ring, this contribution presents the design of transfer lines from the positron and electron sources to the damping ring, and the extraction lines from the damping ring to the high-energy LINAC. The design ensures rapid damping while maintaining beam quality, leveraging advanced lattice configurations. This work outlines the conceptual design, beam dynamics studies, and the technical challenges addressed to meet the demanding operational requirements of the FCCee injector system.
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
FCC-ee ground motion model and SuperKEKB relevant experimental characteristics
The proposed FCC-ee machine is a high-energy, high-intensity and high-precision lepton collider which will require to reduce drastically the differential motions of its two beams at the interaction points (IPs). All undesirable effects on the beam parameters must be analysed in detail, especially in the vicinity of the IP but also along the collider. To assess the beam effects due to vibrations, simulation of magnet motion is necessary. A specially designed ground motion generator, applicable to several locations, is presented. It can take into account the seismic motions and cultural noises observed at the various experimental sites as well as amplifications due to specific mechanical assemblies, such as magnet mounts. To match as much as possible to reality, the generator can be refined with SuperKEKB data. It is an asymmetrical lepton collider which presents many similarities with FFC-ee. In this article, dedicated measurements on this experiment, which are relevant to the FCC-ee ground motion generator, are described such as transfer function of the last cantilever cryostats behaviors, critical magnet supports resonances, and evaluated coherence at various points locations.
Progress towards evaluating different types of colliding beams for a future wakefield-based 10 TeV discovery collider
The 2023 P5 report and recent long-term planning efforts in high-energy physics emphasize the need for a future discovery collider operating at 10 TeV parton center-of-momentum (pCM). A promising candidate is a wakefield-based linear collider, offering various beam options. While conventional electron-positron collisions using flat beams are preferred, challenges with accelerating such beams in wakefield accelerators have led to exploring alternatives like round beams, electron-electron collisions, and gamma-gamma collisions. To evaluate these alternatives, we introduce a modeling framework that assesses their discovery potential. This framework includes detailed simulations of beam dynamics during collisions, accounting for disruption and beamstrahlung effects, to calculate luminosity and particle densities. Geant-4 simulations evaluate detector backgrounds and inform realistic detector designs, enabling studies of physics benchmarks to estimate discovery potential. We present preliminary results for different collision scenarios, highlight the framework's current limitations, and propose future improvements.