bunching
MOXP1
The operational challenges: Achieving 500 mA high beam current at Taiwan Photon Source
1
The Taiwan Photon Source (TPS) has been in routine operation at 500 mA since the last season of 2021, utilizing two superconducting cavities, bunch by bunch feedback system, and fast orbit feedback system, along with many technical efforts. The operation of TPS maintains its high reliability and availability. The mean time between failures is more than 190 hours with an availability greater than 98.9% in 2023. With newly developed cryogenic permanent magnet undulators, IVUs, and EPUs, balancing the needs of both soft X-ray and hard X-ray users. Many challenges have been encountered in the journey to achieving a beam current of 500 mA, primarily due to the short bunch length of 16 ps and impedance issues in vacuum chambers at TPS storage ring. Ongoing efforts to improve the performance and the detailed journey to achieving 500 mA top-up operation will be presented.
Paper: MOXP1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOXP1
About: Received: 23 May 2025 — Revised: 29 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
MOCD3
Observations and efforts to reduce sudden beam loss at SuperKEKB
57
The SuperKEKB accelerator recorded a peak luminosity more than twice that of the KEKB accelerator, but there are various challenges in updating the luminosity beyond that. One of the challenges is to eliminate sudden beam loss (SBL), in which a significant part of the circulating beam is lost in a few short turns. SBLs of the positron ring were investigated and found that the SBLs are characterized by vacuum pressure bursts at specific locations in the ring and an increase in beam size. From these measurements, it can be inferred that some phenomenon occurred at the location where the pressure burst was occurring, causing the beam size to increase and the beam to be lost in the narrow aperture of the ring. We performed knocker tests to artificially cause SBL and looked for possible sources of SBL. Based on several assumptions, we performed several works, including swapping the chamber up and down, cleaning the inside of the chamber, and knocking the chamber before operation. Of these works, the cleaning inside the chamber was found to be likely to be effective. This paper summarizes the measurement of SBL when it occurred and the countermeasures that contributed to its reduction.
Paper: MOCD3
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOCD3
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPB001
Beam dynamics studies and vacuum diagnostics in the Solaris storage ring
69
Since 2015, the National Synchrotron Radiation Center SOLARIS has operated a light source supporting eight experimental beamlines. Following vacuum chamber replacements and beamline upgrades, the total beam lifetime at 400 mA has reached 13 hours in decay mode operation. Regular lifetime measurements are conducted to monitor vacuum quality, residual gas composition, and potential stability issues arising from machine aging. Beam dynamics studies involve measuring electron beam lifetimes at 400 mA, 300 mA, and low currents (as low as 10 mA) under both multibunch and single-bunch operating modes. A particular focus is placed on intra-beam electron interactions influencing the Touschek lifetime and the effects of residual gas on beam scattering. These investigations provide valuable insights into vacuum performance, electron bunch behavior, and overall storage ring dynamics.
Paper: MOPB001
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB001
About: Received: 27 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPB006
Optimal beam energy for ultra low emittance storage rings
83
As new synchrotron light sources push for lower emittances, intra-beam scattering (IBS) becomes an increasingly more important factor in determining the final beam distribution properties. Because IBS depends strongly on beam energy, in the regime of ultra-low emittance rings, beam energy is a parameter to be optimized for best beam performance. In this report, we study the optimal beam energy for various lattices and its dependence on bunch lengthening and damping wigglers.
Paper: MOPB006
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB006
About: Received: 25 May 2025 — Revised: 31 May 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
MOPB019
Flash status 2024 - FEL operation for users and upgrade shutdown
102
FLASH, the XUV and soft X-ray free-electron laser at DESY, is currently undergoing the 2nd of two long upgrade shutdowns within the FLASH2020+ project. The 1st half of 2024 was dedicated to user operation. The upgrade shutdown started in June 2024, and we plan to come back to beam operation in August 2025. Here we will discuss the operational highlights of the first half of 2024, briefly describe the new features being implemented, and report on the shutdown status.
Paper: MOPB019
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB019
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPB037
Orbit alignment study in the collimation section at the European XFEL
142
Orbit alignment plays an important role in free-electron laser (FEL) facilities, particularly in the collimation section, where multipoles are strategically positioned near the collimators as part of the specialized optics design. At the European XFEL, a strong dependence of lasing performance on the orbit in the collimation section has been observed. This study focuses on calibrating the central positions of the collimators using an orbit bump scanning technique combined with beam loss detection. Additionally, the influence of orbit alignment in the collimation section on lasing performance was systematically investigated, offering valuable insights into optimizing FEL operation.
Paper: MOPB037
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB037
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
MOPB041
CW SRF gun generating beam parameters sufficient for CW hard-X-ray FEL
154
SRF CW accelerator constructed for Coherent electron Cooling project at Brookhaven National Laboratory frequently demonstrated record parameters using 1.5 nC 350 psec long electron bunches, typically compressed to FWHM of 30 psec using ballistic compression. In this paper we report experimental demonstration of CW electron beam with parameters fully satisfying all requirements for hard-X-ray FEL and significantly exceeding those demonstrated by APEX LCLS II electron gun. The most remarkable part of this achievement in this experiment that we used 10-years old SRF gun with modest accelerating gradient ~ 15 MV/m, a bunching cavity followed by basilic compression to generate 50 pC, 15 psec electron bunches with normalized emittance of 0.15 mm mrad and normalized project emittance of 0.2 mm mrad. In other words, we are presenting alternative method of generating CW electron beams needed for hard-X-ray FELs using existing and proven accelerator technology. We present description of the accelerator system setting, details of projected and slice emittance measurements as well as relevant beam dynamics simulations.
Paper: MOPB041
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB041
About: Received: 30 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
MOPB049
Characterisation of beam dynamics sensitivity to misalignments in the PERLE injector
165
High current linear accelerators require the precise alignment of accelerating cavities to maintain a high beam quality. The PERLE (Powerful Energy Recovery Linac for Experiments) injector cryomodule is composed of four single-cell cavities, each of which can be independently tuned to allow greater control of the beam at this crucial point. Misalignments can lead to perturbations in the beam trajectory and contribute to an increased emittance and energy spread. Here we present a characterisation of the beam dynamics when various misalignments are applied in the injector. Various misalignments are applied, three in the translation axis (x, y, z), and two rotationally, yaw and pitch (𝚽, 𝚹). A study was conducted to determine the tolerances required misalignments to ensure an acceptable beam quality is maintained at. The results indicate that particular combinations of rotational and translational misalignments are especially detrimental to emittance. These findings provide an important guide for the subsequent design of the booster linac and alignment procedure.
Paper: MOPB049
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB049
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPB054
Evaluation of coating thickness and thermal deposited power for nonlinear in-vacuum kicker
173
This paper presents a comprehensive evaluation of the relationship between titanium coating thickness and thermal deposited power in the ceramic chambers of the Nonlinear In-vacuum Kicker (NIK) system, a critical component in synchrotron light sources. The study focuses on optimizing the coating thickness to minimize magnetic field attenuation and thermal load, thereby enhancing the performance of the NIK system. Through simulation analysis, we demonstrate that a titanium coating thickness of 5 μm provides an optimal balance between magnetic field attenuation and thermal load management. Additionally, the uniformity of the coating layer is found to significantly impact the system's stability and efficiency. The findings offer valuable insights for the design and operation of NIK systems in synchrotron facilities, particularly for the Taiwan Photon Source (TPS).
Paper: MOPB054
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB054
About: Received: 07 May 2025 — Revised: 01 Jun 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
MOPB060
Generation of short current spikes by laser modulation at FLASH
187
Generating few- or sub-femtosecond radiation pulses in a free-electron laser (FEL) requires precise control of the longitudinal phase space density of the driving electron bunch, as the FEL process depends strongly on the bunch current and energy spread profile. In an experiment conducted at FLASH in Hamburg, Germany, an energy modulation with linearly changing amplitude is imprinted onto part of the bunch by a laser pulse in an undulator upstream of the first bunch compression chicane. In subsequent longitudinally dispersive sections, a short current spike is created, as the linearly modulated region is compressed more strongly than the rest of the bunch. Measurements with a transverse-deflecting X-band cavity verify the creation of a short current spike, whose duration falls below the temporal resolution of the measurement setup of approximately 7 fs.
Paper: MOPB060
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB060
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
MOPB080
Study of DESY II as an injector option for PETRA IV storage ring
220
PETRA IV is the storage ring light source currently under design at DESY in Germany. The baseline injector is a 6-GeV synchrotron DESY IV, an upgrade to the existing injector DESY II. Even if the project progresses in developing the DESY IV, we studied the intensity limit of DESY II to investigate the feasibility of reusing the existing injector chain, in view of a possible upgrade to a laser plasma injector in the coming years. We identified the microwave instability-induced energy spread and the transient beam loading as a limiting mechanism of single-bunch intensity in a 12.5 Hz cycle synchrotron. This paper reports the numerical simulation, its analysis, and its follow-up experiments of high charge acceleration at DESY II and its subsequent injection into PETRA III. The injection efficiency of DESY II's beam into future PETRA IV is also computed assuming imperfect lattices with 5% beta-beating. To overcome the intensity limit set by the pre-accelerator PIA, we investigated the possibility of multi-cycle accumulation at low energy. In this regard, we measured the lifetime and emittance over cycles and the chromaticities of the lattice. These are also reported in the paper.
Paper: MOPB080
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB080
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
MOPB089
Status of Sirius operation with users
228
SIRIUS is a state-of-the-art synchrotron light source facility, featuring a 3 GeV electron storage ring with a 518 m circumference and 250 pm·rad emittance. Built and operated by the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas, Brazil, SIRIUS has undergone significant upgrades over the past year. These include the installation of a cryogenic plant, superconducting RF cavities, in-vacuum undulators, and new orbit feedforward systems, among others. This report summarizes these developments, highlights improvements in beam stability, and provides an overview of the facility’s operational status over the past year.
Paper: MOPB089
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB089
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPB093
Study on pre-bunched free electron laser in the terahertz wavelength range
232
We have been studying about a pre-bunched FEL in the THz region. In the pre-bunched FEL, the electron bunches being compressed shorter than the oscillation laser wavelength, it is expected that we can generate short-pulse THz laser pulses with high peak intensity. A broadband spectrum and high-intensity characteristics, which cannot be realized by conventional FEL, are expected. The pre-bunched FEL experiments were conducted using the THz-CUR at Kyoto University Free Electron Laser (KU-FEL) consists of an existing electron rf gun (ECC-RF-Gun), which can produce short electron bunches adequate for pre-bunched FEL, and a 10-period undulator. We installed an optical cavity and performed beam tests at the lasing frequency of 0.2 to 0.4 THz. As the results of beam test, we observed the coherent stacking of coherent THz pulses inside the cavity, however, FEL oscillation has not been achieved yet. We will report on our pre-bunched FEL project, experimental setup, beam test results and future prospects.
Paper: MOPB093
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB093
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
MOPB098
Simulation studies on optimization of hard and soft X-ray beamlines for parallel user service at the PAL-XFEL
235
PAL-XFEL (Pohang Accelerator Laboratory X-ray Free Electron Laser) is a facility that generates high-brightness FEL for users to perform the FEL-based sciences. Currently hard and soft X-ray (HX/SX) beamlines are operational, but the parallel operation can be done with less than 60 Hz using a single electron bunch from the electron injector. Therefore, for the user service with maximum repetition rate of 60 Hz on both HX and SX beamlines, a scheme that uses two bunches from the injector with an exact single cycle of 2.856 GHz frequency is under consideration. Particularly, simulation study is necessary to understand the optimal accelerator condition for both HX and SX since the SX shares the same accelerator condition up to the third accelerating column with the HX beamline. In this study, we show discussions using the particle tracking simulations showing the optimal conditions for both beamlines. We also present the potential issues to be considered in the actual operations such as error of RF cavity amplitude.
Paper: MOPB098
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB098
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
MOPB101
Bayesian optimization for the local bump injection in the HLS-II storage ring
242
Currently, a conventional local bump injection system with four pulsed dipole kicker magnets is adopted in the Hefei Light Source II (HLS-II) storage ring to achieve topoff operation. Due to the multipole magnets located between the kickers in the injection section, the local bump injection presents technical challenges in forming a perfect closed bump, which causes oscillation to the stored beam. In order to reduce the injection disturbance on the stored beam, the Bayesian Optimization (BO) method is employed to determine the kick angles of the four bump kickers.
Paper: MOPB101
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB101
About: Received: 09 Apr 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
MOPB105
Simulation and optimization of a sub-THz Cherenkov FEL at AREAL
246
A circular waveguide lined with a thin dielectric layer enables electron bunches propagating within the structure to radiate light in the (sub-)THz regime. In this work, we perform simulations of low-energy electron beams traversing extended waveguides to analyze the dynamics of beam bunching and lasing within the structure. By exploring the free-electron laser (FEL) process in this context, we demonstrate the potential of waveguides as a cost-effective alternative to undulator-based FELs. The study employs a simulated model of the AREAL LINAC at the CANDLE SRI to demonstrate these effects and provide realistic results. The simulations are performed using the space charge tracking algorithm ASTRA and the wakefield solver ECHO. For optimization of the system, the genetic optimization algorithm GIOTTO is applied to refine both the waveguide and accelerator variables. Using a 4 MeV electron beam with a charge of 300 pC, the optimized setup achieves a radiation frequency of 100 GHz with energy outputs exceeding 20 µJ in a waveguide of only 1.2 meters length. These results underscore the feasibility of this method, offering a innovative pathway to produce intense THz radiation.
Paper: MOPB105
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB105
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPB106
Optimizing Cherenkov waveguide seeding for THz SASE FELs towards stable, few-cycle pulses
250
The PITZ facility at DESY in Zeuthen has demonstrated the first operational high peak and average power THz self-amplified spontaneous emission (SASE) free electron laser (FEL). The current setup displays the onset of saturation at a central frequency of 3THz using a 3.5m long LCLS-I undulator. However, the THz user community has expressed the need for carrier-envelope phase (CEP) stability and the availability of few-cycle THz pulses to complement the currently demonstrated long pulses. In this work, simulations are conducted to evaluate and optimize FEL performance by incorporating a Cherenkov waveguide to seed the process. The waveguide parameter space is scanned to vary energy modulation depth and frequency, after which the performance is estimated using the space charge tracking algorithm, ASTRA, and the FEL simulation code, Genesis1.3. The optimized parameters allow saturation to be reached much earlier, while also significantly increasing the shot-to-shot stability. Down the line, the implementation of such a scheme would facilitate generation of few-cycle, CEP-stable THz pulses to be used in user experiments.
Paper: MOPB106
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB106
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPB108
Coherent undulator radiation with account of the beam energy spread
254
When a microbunched beam is sent to a resonantly tuned undulator it radiates coherent radiation with the intensity propotional to the bunching squared of the beam. According to *, the radiated energy increases with the undulator length. This conclusion, however, is only valid if one ignores the energy spread of the beam (and also the beam angular spread). The finite energy spread smears the microbunching, ultimately suppressing coherent radiation beyond a certain distance. In this work, we calculate the radiation of a microbunced beam with an energy spread and find the maximum energy that it can radiate coherently.
Paper: MOPB108
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB108
About: Received: 22 May 2025 — Revised: 30 May 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
MOPM001
RHIC Au operation in Run24
264
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: 10 Jul 2025
MOPM007
FCC-ee energy calibration and polarization - Status and outlook
274
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: 10 Jul 2025
MOPM008
Towards a High Luminosity LHC with even higher performance
278
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: 10 Jul 2025
MOPM011
Bayesian optimization for IP aberration correction and luminosity tuning in FCC-ee
290
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: 10 Jul 2025
MOPM012
Parameter and luminosity scenarios for FCC-hh
294
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: 10 Jul 2025
MOPM013
Modelling resonant depolarisation
298
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: 10 Jul 2025
MOPM015
Optimizing cavity detuning at high beam intensities in the LHC
306
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: 10 Jul 2025
MOPM016
Comparison of BCMS and standard beams at LHC injection energy
310
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: 10 Jul 2025
MOPM017
Do transverse bunch tails produce luminosity?
314
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: 10 Jul 2025
MOPM021
Proof-of-principle experiment to reconstruct the trajectory of dust grains interacting with the LHC beams
330
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: 10 Jul 2025
MOPM022
Criticality of powering failure of the main bend circuits in the FCC-ee at the Z-pole energy
334
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: 10 Jul 2025
MOPM023
Damage potential and machine protection criticality of the FCC-ee beams
338
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: 10 Jul 2025
MOPM029
Progress on the 10 TeV center-of-mass energy muon collider
362
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: 10 Jul 2025
MOPM030
Impact of collective effects on beam stability in the FCC-ee main rings and the high-energy booster
366
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: 10 Jul 2025
MOPM041
Estimation of FCC-ee beam lifetime from full lattice tracking
410
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: 10 Jul 2025
MOPM043
Comparison of particle in cell and soft-Gaussian beam-beam solvers
414
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: 10 Jul 2025
MOPM045
A numerical study on injection efficiency improvement at SuperKEKB electron ring
422
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: 10 Jul 2025
MOPM046
Generation of GeV-range photons via Inverse compton scattering at the FCC-ee
425
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: 10 Jul 2025
MOPM047
Laser Compton backscattering for precision beam intensity control in the FCC-ee electron-positron collider
429
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: 10 Jul 2025
MOPM048
Study of the coherent < x-z > instabilities for FCC-ee
433
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: 10 Jul 2025
MOPM049
Longitudinal wakefield implementation in the circulant matrix model
437
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: 10 Jul 2025
MOPM058
Beam tracking simulation of the capture LINAC for the ILC e-driven positron source
453
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: 10 Jul 2025
MOPM060
CETASim: a numerical tool for beam collective effect study in storage rings
456
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: 10 Jul 2025
MOPM061
Study of single bunch effect in PETRA-IV storage ring
459
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: 10 Jul 2025
MOPM063
Collimator damage study for the Diamond-II storage ring
462
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: 10 Jul 2025
MOPM077
Commissioning of the new FLASHlab@PITZ beamline extension
498
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: 10 Jul 2025
MOPM087
Design of the FCC-ee injector linacs up to 20 GeV beam energy
527
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: 10 Jul 2025
MOPM100
Benchmarking the LHC impedance model through loss of Landau damping measurements and simulations
552
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: 10 Jul 2025
MOPM101
Upgrade of the LHC main RF system for HL-LHC
556
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: 10 Jul 2025
MOPS004
Longitudinal hollow electron beam
588
The intra-beam scattering in high charge state intense heavy ion beams is a problem worth considering. With the help of controlling the longitudinal distribution of the ion beam, it may be possible to alleviate the ion beam loss and to improve the ion beam lifetime caused by intra-beam scattering. Unlike the traditional cooling process of direct current electron beams or longitudinal uniform distribution electron beams, a longitudinal hollow electron beam is used to cool heavy ion beams. Ions at the edge of the ion beam will receive stronger cooling, while ions at the center of the ion beam will receive weaker cooling, avoiding overcooling at the center of the ion beam. This paper discusses the generation, measurement, and related issues of longitudinal hollow electron beams. Corresponding solutions and suggestions have been proposed for the problems and challenges that may be encountered in the research. The cooling process of longitudinal hollow electron beams will be simulated and experimentally studied in the further, with the hope of obtaining beneficial effects.
Paper: MOPS004
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS004
About: Received: 09 May 2025 — Revised: 30 May 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
MOPS005
Adiabatic capture in high-intensity, high-power rings
592
Finding the optimal RF voltage ramp to capture coasting beams in high intensity rings has been the subject of ongoing study for many decades. We are motivated to revisit the topic with a view to capturing coasting, stacked beams in a future high intensity, high power FFA. However, the results have general applicability. We compare various voltage laws including linear, bi-linear and iso-adiabatic through simulation and experimentally, making use of the ISIS synchrotron. Making use of longitudinal tomography, we seek to establish the voltage program that minimises the captured beam emittance.
Paper: MOPS005
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS005
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPS023
Design of the front-end complex for a muon cooling demonstrator at CERN
643
The muon collider has great potential for enabling high-luminosity multi-TeV lepton-antilepton collisions provided low-emittance, high-intensity muon beams can be produced. Ionization cooling is the proposed technique to achieve the required muon beam emittance. The International Muon Collider Collaboration aims to demonstrate the integration and reliable operation of a 6D ionization cooling system, including RF acceleration in strong magnetic fields. This study focuses on the design of the muon production and transport systems for a Muon Cooling Demonstrator facility in the CERN TT7 tunnel. A new implementation based on the CTF3 building is also presented, offering improved layout flexibility and beam intensity. FLUKA simulations are used to optimize the target and magnetic horn geometries to maximize pion production and capture, assuming a 14 GeV proton beam from the Proton Synchrotron (PS). The transport line, designed to deliver 190 – 210 MeV/c muons into the cooling channel, consists of a short pion decay section, followed by a momentum-selecting chicane and a matching section. The chicane integrates collimation and phase-rotation systems for transverse and longitudinal tuning of the muon beam. Beam optics for the transport lattice are designed in MAD-X, with tracking studies performed using BDSIM.
Paper: MOPS023
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS023
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPS028
Preparing the future SPS fixed target beams for the SHiP experiment
659
A new high-intensity Beam Dump Facility (BDF), hosting the SHiP (Search of Hidden Particles) experiment, is set to begin operation in CERN’s North Area (NA) in Run 4. To meet its physics goals, SHiP aims at accumulating 4$\times$10$^{19}$ protons on target per year, which will require approximately 10$^6$ high intensity cycles from the SPS with $4.2\times10^{13}$ p$^+$ per cycle (as operationally used during the CNGS era) over a $1$ s spill length. To reduce the future supercycle load and thus minimize the impact on the other physics facilities (especially at the CERN PS complex delivering the beam to the SPS), a strategy involving higher intensity per spill but a smaller number of spills for SHiP was proposed. In this context, a series of studies have been initiated to explore the intensity limits of the North Area beams in the SPS. This contribution presents the initial results on the correction of the intensity dependent tune shift induced by the beam coupling impedance and the transverse optimizations required for operating at higher intensities.
Paper: MOPS028
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS028
About: Received: 26 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
MOPS034
Increasing single-bunch intensity limit at ESRF-EBS with high coupling
679
Synchrotron radiation light sources normally operate at a low coupling between the transverse planes in order to achieve flat beams and produce high peak brilliance. Instead, operating at a high coupling has other advantages such as smaller emittance degradation due to intra-beam scattering, improved Touschek lifetime, and lower sensitivity to vibrations of the photon beam. Moreover, it has been suggested that a high coupling may enable achieving higher bunch currents thanks to sharing of the beam-induced wakefields between the transverse planes. We were able to take advantage of this effect to substantially increase the TMCI threshold at zero chromaticity and nearly double the single bunch current limit at high chromaticity at ESRF-EBS.
Paper: MOPS034
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS034
About: Received: 14 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
MOPS038
Simulations of bunch length reduction techniques in the SLS booster
690
Modern injection schemes for light sources seek to explore the full 6D phase space in order to find creative ways of top-up injection with minimal perturbation to the stored beam. The longitudinal injection scheme is considered for the SLS 2.0 storage ring and, hence, the longitudinal profile of the injected beam becomes highly relevant for the injection efficiency. We simulate possible ways of reducing the bunch length in the SLS booster synchrotron. The feasibility of increasing the total RF voltage by installing additional or different RF cavities is considered. Furthermore, we simulate the impact of pulsed- or oscillating RF voltages and phases in order to compress the beam longitudinally at the expense of an increased energy spread.
Paper: MOPS038
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS038
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
MOPS041
Status of the beam dynamics studies for the PERLE Energy Recovery Linac
702
PERLE (Powerful Energy Recovery Linac for Experiments) is a three-turn, high power Energy Recovery Linac under construction at IJCLab, France. It emerged from the design of the LHEC and FCC-eh and will serve as a hub for the validation of several technical choices and exploration of a broad range of accelerator phenomena in an unexplored operational power regime (up to 10 MW in its final version). Up to now, the final lattice design and phasing has been finalised. Current studies focus on non-linear effects and longitudinal dynamics. Also, the commissioning scheme is under developpement. We will present the status of the beam dynamics studies of the project, and highligth some of the ongoing studies
Paper: MOPS041
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS041
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPS045
Considerations of a round beam operation at PETRA IV
710
Round beam operation is considered for the planned ultra-low emittance storage ring PETRA IV at DESY, Hamburg. With a natural emittance of 20 pm rad, we evaluate and discuss the advantages and challenges of sharing the emittance between transversal planes. The effect on single and coupled bunch instability thresholds, intra-beam scattering rates and Touschek lifetime of this operation mode are presented.
Paper: MOPS045
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS045
About: Received: 26 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
MOPS046
Beam loading for counter-rotating high-intensity beams in the Muon collider
714
Muon colliders promise an efficient path to a multi-TeV energy collider facility. In the greenfield study, the final stage of the acceleration chain is planned as a series of four rapid-cycling synchrotrons (RCS). In each RCS, the RF systems are divided into several sections and shared by the two counter-rotating muon bunches. The accelerator requirements are driven by the need to preserve a maximum number of muons by taking advantage of time dilation. Therefore, maintaining a high accelerating voltage throughout the chain is essential, imposing superconducting RF cavities in the GV range. However, the high bunch intensity of up to $2.7\times 10^{12}$ particles per bunch and the 1.3 GHz TESLA cavity’s small aperture will result in induced voltages in the MV range. In the muon collider, the induced voltage of the counter-rotating beams will additionally impact the cavity voltage. This contribution presents the cavity voltage modulation and its impact on the beam loss and stability in the strong transient beam loading regime.
Paper: MOPS046
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS046
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
MOPS049
Beam loss scenarios for the SOLEIL II upgrade
726
SOLEIL II is an ambitious upgrade project that aims to reduce the horizontal emittance of the SOLEIL facility from 4 nm to 84 pm (to be further reduced to 50 pm by running with round beams). The SOLEIL II lattice will utilise a combination of permanent magnets and electro-magnetic corrector magnets. In the case of beam losses, it is of critical importance to localise the losses to certain shielded areas or dedicated collimators in order to prevent the risk of demagnetisation of the permanent magnets. The study and development of different beam loss scenarios will be presented.
Paper: MOPS049
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS049
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
MOPS051
Light upgrade of the ESRF booster
730
The ESRF booster has been built more than 30 years ago as injector of the first ESRF storage ring and it is still used to inject in the EBS. Several components of the booster have been updated in the years and it is now operated off-energy and with emittance exchange at extraction, however the lattice has not been modified since the '90s. A project to reduce the equilibrium emittance and bunch length of the booster by exchanging 18 quadrupole magnets has been proposed. In this paper we present the beam dynamics studies in presence of errors and the expected gain in injection efficiency.
Paper: MOPS051
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS051
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
MOPS052
Overview of ESRF-EBS's four-year operation and strategy for further upgrade
733
The user operation of the Extremely Brilliant Source (EBS) since August 2020 has opened a new era of high energy fourth generation synchrotron radiation light sources. During the following four years of operation, the EBS accelerator has sustained user operation with high availability, reliability, and stability, and has continued to improve beam performance by reducing injection perturbations, increasing bunch/beam currents for different beam delivery modes, and consolidating the storage ring operation with a hot-swap power supply system, newly designed kicker ceramic chambers, etc. Sustainability has always been key to EBS operation and future upgrades. During user operation, measures on the RF system of the storage ring and HQPS operation have been implemented to save power consumption; in the near future, solid-state amplifiers and 4th harmonic RF system projects will ensure the sustainability of machine operation further. In addition, as a strategy for future upgrades of the EBS accelerator complex, injector upgrades are being considered, including the injection with a new linac, which can be further upgraded to inject full-energy beam into the storage ring.
Paper: MOPS052
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS052
About: Received: 29 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
MOPS061
MAX 4U: an upgrade of the MAX IV 3 GeV ring
752
The MAX IV 3 GeV storage ring in Lund, Sweden, was the first implementation of a multibend achromat (MBA) lattice fourth-generation light source. Since it started delivery of light in 2016, three succeeding MBA-based rings and variants have come on-line: ESRF-EBS, Sirius and APS-U. Several others are being planned, designed, built or commissioned. All of these capitalize on the MBA concept and expand it to push the brightness and coherence performance even further. In order to continue to offer the Swedish and international scientific communities competitive tools beyond the end of this decade, MAX IV Laboratory launched in 2024 the conceptual design of MAX 4U , an upgrade of its 3 GeV storage ring aiming at an emittance below 100 pmrad. This performance boost is to be achieved through a minimum-interference upgrade in which localized interventions in selected subsystems and components are carefully chosen to provide the maximum performance increase with minimum cost and, equally important, minimum dark time for the MAX IV user community. This contribution describes the accelerator physics and engineering aspects of the MAX 4U conceptual design and presents the latest developments.
Paper: MOPS061
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS061
About: Received: 21 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
MOPS069
The Elettra 2.0 project status
768
After 31 years of serving the user community with excellent results, on July 2nd 2025 the removal of the Italian third generation synchrotron light source Elettra (www.elettra.eu) will start to be replaced by Elettra 2.0 a fourth-generation one. The project is in full development and, being a diffraction limited light source, Elettra 2.0 will provide ultra-high brilliance and coherence to the experiments while at the same time the machine is designed to provide very short pulses for time resolved experiments. The project status and its possibilities will be presented and discussed
Paper: MOPS069
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS069
About: Received: 24 Apr 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
MOPS079
Operational deployment of high brightness LHC beams in the SPS
778
Following the LHC Injector Upgrade programme (LIU) there has been a gradual ramp-up of the intensity of LHC beams in the CERN Super Proton Synchrotron (SPS). This was initially hampered by vacuum issues in several critical components, such as RF cavities and kicker magnets, requiring extensive scrubbing campaigns to condition these components. This paper reviews the current status of the high brightness LHC beams in the SPS, including commissioning evolution, aspects related to beam stability and beam optimization and the current brightness reach. An assessment of the operational readiness of these beams for the High Luminosity LHC era is also given.
Paper: MOPS079
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS079
About: Received: 26 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUXN1
Elevating beam quality and stability in linear accelerators through high order mode analysis
850
The pursuit of optimal beam quality and stability in linear accelerators (Linacs) stands as a cornerstone of accelerator physics. However, the presence of High Order Modes (HOMs) within Linacs, particularly in the context of energy recovery (ERLs), presents formidable challenges to beam quality and stability. In response to this challenge, the development of the Compact HOMEN (High Order Mode Evolution based on Energy budget) model has emerged, providing precise prediction and analysis of HOM effects on beam dynamics within superconducting cavities. This model facilitates meticulous optimization strategies, guiding researchers towards unprecedented advancements in high-brightness accelerated electron beam technology. By comprehensively understanding and managing HOMs, Linacs can achieve enhanced performance and efficiency, crucial for a myriad of scientific and industrial applications. Through this study, we underscore the constraints posed by high currents and high repetition rate to ensure an optimal energy recuperation. Our findings not only deepen the understanding of ERL facilities but also underscore their transformative potential in shaping the forefront of accelerator technology.
Paper: TUXN1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUXN1
About: Received: 21 May 2025 — Revised: 29 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
TUAN3
Comprehensive study of Robinson instability in active and passive higher harmonic cavities for bunch lengthening
874
Higher harmonic cavities (HHCs) play a critical role in storage rings by extending the bunch length, thus mitigating beam instability and increasing the beam lifetime. This study investigates the influence of Robinson instability on the bunch lengthening performance for both active and passive HHCs. A detailed comparison is conducted to analyze the Robinson instability thresholds* and the parameters of the HHCs** that govern the onset of instability. Simulation results and theoretical analysis are combined to provide guidelines for optimizing HHCs configurations to balance effective bunch lengthening with stability requirements. As illustrative examples, we consider an active normal-conducting HHC for Korea-4GSR , and a passive superconduting HHCs for PLS-II.
Paper: TUAN3
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUAN3
About: Received: 05 Jun 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUYN1
Electron-Ion Collider status
878
The Electron-Ion Collider (EIC), which is being designed by BNL, JLab and other partners, will be a particle accelerator that collides electrons with protons and nuclei to produce snapshots of those particles' internal structure. It will collide polarized high-energy electron beams with hadron beams in the center-of-mass energy range of 20-140 GeV. The electron beam, employed as a probe, will reveal the arrangement of the quarks and gluons that make up the protons and neutrons of nuclei. The EIC will allow us to study the "strong nuclear force", the role of gluons in the matter within and all around us, and the nature of particle spin. This talk will describe the Electron-Ion Collider design and construction at Brookhaven National Lab.
Paper: TUYN1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUYN1
About: Received: 28 May 2025 — Revised: 29 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
TUBN3
Exceeding high-luminosity LHC performance targets during the 2024 Pb-Pb ion run
899
We review the 2024 Pb-Pb ion run at the Large Hadron Collider (LHC), in terms of the operational experience, the problems encountered and the main results. This run was the second heavy-ion physics period of LHC Run 3 at 6.8 Z TeV. With only 18 days scheduled for physics data-taking, the key objective was to address the problems encountered in the 2023 Pb-Pb run and establish stable and efficient operation. Thanks to several mitigation measures, the 2023 limitations were overcome, significantly improving the machine availability. Together with substantially higher intensity, thanks to the excellent performance of the Pb ion injectors, this paved the way for a record-high performance in terms of average daily integrated luminosity with ion beams at the LHC.
Paper: TUBN3
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUBN3
About: Received: 15 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
TUCD2
Commissioning of the Advanced Photon Source upgrade - the first swap-out injection-based synchrotron light source
915
The Advanced Photon Source (APS) recently completed a transformative upgrade, replacing its 25-year-old storage ring with a state-of-the-art hybrid seven-bend achromat lattice with six additional reverse bends. The new design features a low natural emittance of 42 pm-rad, enabling productions of X-rays up to 500 times brighter than the original APS. The upgrade introduced a pioneering swap-out injection scheme, replacing entire depleted bunches rather than topping them up. This approach enables on-axis injection to accommodate for the reduced dynamic aperture resulting from strong focusing. The paper describes the commissioning process, operating experience with swap-out injection, and gives performance parameters of new systems such as the bunch-lengthening cavity.
Paper: TUCD2
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUCD2
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
TUPB005
Measurement of the muon rate at the SND Experiment with the Timepix3 radiation monitor
944
Using a Timepix3 radiation monitor, the muon rate at the Scattering and Neutrino Detector (SND) location at the Large Hadron Collider (LHC) was measured during luminosity production at the ATLAS collision point. Filters are applied on the measured data to distinguish between background radiation and the muon signal by analyzing the cluster type, length, and angle. The results were compared to the those reported by SND, revealing a count rate ratio of 1.24 of Timepix3 to SND measurements. Taking advantage of the Timepix3 detector capabilities, further features of the muon flux are studied. First, the bunch-by-bunch spacing (25 ns) of the beam is assessed owing to the time resolution of the Timepix3 detector (1.5265 ns). The spatial distribution of the muon flux in the Timepix3 detector surface has been studied, however the detector size is too small for the measured muon rate to yield any distinct patterns, assuming the muon gradient as measured by the SND detector. Finally, the energy deposition $E_{dep}$ of the muons in the Timepix3 detector has been studied, consistent with FLUKA simulated muons coming from ATLAS collisions, with an energy distribution peaked at 100 GeV.
Paper: TUPB005
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB005
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
TUPB014
The Experimental Storage Ring (ESR) - recent developments
976
The Experimental Storage Ring (ESR) at GSI Darmstadt, Germany is the core instrument for unique physics experiments. It is operated for accumulation, storage, cooling and deceleration of a wide range of heavy ion beams in the energy range from 4-400 MeV/u coming from the synchrotron SIS18 via the FRagment Separator (FRS) or a direct transport line. Low energy decelerated beams can also be fast extracted to the storage ring CRYRING or to the HITRAP facility. The overview of the ESR performance, will be presented here. The features and challenges of the operation with the new control system LSA (LHC Software Architecture) will be outlined as well.
Paper: TUPB014
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB014
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPB020
Injection simulations of space charge dominated proton beams in IOTA
995
A 2.5 MeV proton injector is being constructed for the IOTA ring at Fermilab to study the interaction of nonlinear integrable optics (NIO) with high space charge beams. Space charge in the transport line from the RFQ to the injection location has a significant current dependent effect on the phase space. Simulation studies to support efficient injection of intense bunches into IOTA are presented, included schemes to inject directly into NIO lattices.
Paper: TUPB020
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB020
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
TUPB075
Bunch lengthening of the extraction beam using second harmonic in J-PARC RCS
1132
The 3GeV Rapid-Cycling Synchrotron (RCS) at J-PARC supplies the beam to the Main Ring (MR). Under the current operating conditions, there is the longitudinal beam mismatch between RCS and MR. To improve the RCS-MR longitudinal matching, a method for the bunch lengthening of RCS at the extraction is proposed. The method is based on introducing a second harmonic RF voltage at beam extraction and placing the beam at the unstable fixed point. The considerations of the bunch lengthening in the RCS are described in this presentation. The focus is on optimizing the second harmonic RF voltage pattern. Demonstrations of introducing a second harmonic RF voltage are also discussed.
Paper: TUPB075
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB075
About: Received: 07 Apr 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPB090
Impedance analysis for the ALS-U kickers
1139
We present recent impedance modeling studies of the kicker systems developed for the Advanced Light Source Upgrade (ALS-U), including ferrite-loaded kickers, stripline-type fast kickers, and septa. The modeling supports the injection/extraction systems to ensure beam stability in the accumulator and storage rings. In addition, it provides guidance for component fabrication and offline testing by incorporating realistic factors such as mechanical tolerances and assembly specifications.
Paper: TUPB090
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB090
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM004
Simulations and experimental commissioning results of the AWAKE Run 2 photoinjector
1171
AWAKE (Advanced Wakefield Experiment) is the world’s first proton-driven plasma wake field acceleration experiment and has demonstrated the acceleration of electrons to several GeV’s in its first Run. The goal of Run2 is acceleration of a witness bunch whilst preserving beam quality and experiment scalability. AWAKE drives high gradient plasma wake fields using a proton beam, then a secondary electron beam is accelerated which is externally injected from a dedicated injector which consists of an S-band Rf-gun and an X-band bunching and acceleration system. This S band RF-Photoinjector for the AWAKE Run 2 experiment at CERN is currently being commissioned. The obtained experimental results are presented and compared to simulations in this paper. Overall, the commissioning demonstrates successful matching of beam parameters with the design values, supported by ASTRA simulations. This lays the groundwork for low emittance electron beam injection into the AWAKE plasma and opens possibilities for future high-gradient acceleration experiments.
Paper: TUPM004
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM004
About: Received: 19 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
TUPM010
First THz light generated in high energy section of FLUTE
1186
FLUTE is a compact and flexible linac-based accelerator test facility at the Karlsruhe Institute of Technology (KIT) in Germany. It serves as a platform for a variety of accelerator studies and to generate intense short THz pulses for various photon science experiments. Later, FLUTE will be also used as an injector of sub-100 fs bunches into the VLA-cSR (Very Large Acceptance compact Storage Ring), which is part of the cSTART (compact STorage Ring for Accelerator Research and Technology) project currently in the technical design phase at KIT. Recently, FLUTE's high energy section has been installed and commissioned. This includes the linac, bringing FLUTE beyond 5 MeV to full energy, the bunch compressor, and two corresponding diagnostics sections. A metal foil in the last diagnostics section has been used to generate a first THz signal with high energy electron bunches.
Paper: TUPM010
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM010
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM012
Stable generation of high-quality beam by 3-GeV low-emittance linear accelerator in NanoTerasu
1189
The construction of a low-emittance 3-GeV linear accelerator as an injector system of a new high-brilliance synchrotron radiation facility “NanoTerasu” was completed in January 2023. After beam commissioning of the accelerator complex for several months, the synchrotron radiation for user experiment was provided in April 2024 as planned [*]. The 3-GeV compact linear accelerator consists of 40-MeV injector system and C-band accelerator. The electron beam with a bunch charge of more than 0.5 nC and normalized emittance of less than 2 mm mrad is generated from an electron RF gun system with a gridded thermionic cathode at a “transparent” grid condition [**]. In the 40-MeV injector system, the bunched beam with a bunch length of 5 ps and normalized emittance of less than 10 mm mrad is generated. In usual operation, the bunched beam is accelerated up to 3 GeV and injected stably into the storage ring. In this presentation, we report on the establishment of beam adjustment by tuning RF amplitude and phase. We also report on the beam performance obtained, including beam stability, and comparing the design beam envelope and measured beam optics in the linear accelerator.
Paper: TUPM012
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM012
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
TUPM014
Deflecting cavity-based multifunctional longitudinal manipulator for CSR-mitigated bunch compression
1192
A deflecting cavity is an interesting tool providing a coupling between transverse and longitudinal planes. Several methods employing deflecting cavities have been proposed to shape current profiles or adjust longitudinal chirp. Even, a method using deflecting cavities was recently proposed for imparting arbitrary correlation on the longitudinal phase space. In this work, we introduce an integrated deflecting cavity-based beam manipulator capable of simultaneously controlling three longitudinal properties: chirp, linearity, and current profile. This relatively compact system can provide a linearized longitudinal chirp for bunch compression without requiring linac phase control and harmonic linearizers. Also, it generates a current profile that flattens the CSR wake, thereby minimizing emittance growth caused by CSR. The presentation includes the working principle of the system and simulation results.
Paper: TUPM014
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM014
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
TUPM021
An update of progress on the design of the diffraction line for the relativistic ultrafast electron diffraction and imaging facility at Daresbury Laboratory
1208
The Relativistic Ultrafast Electron Diffraction and Imaging (RUEDI) facility is an approved project to provide ultrafast capability to UK researchers. The current design involves two separate beamlines for diffraction and imaging but with shared infrastructure including laser pump sources. This presentation describes recent progress in the design of the diffraction line. The diffraction line has a 2.4 cell S-band RF gun to produce 4 MeV electron bunches. Bunch compression to the sub-10 fs range is carried out with a triple bend achromat design that also suppresses arrival time jitter*. Interchangeable sample chambers are planned to allow wide ranging experiments from both solid samples at room and cryogenic temperatures and liquid and gas targets. Post sample optics are provided to image the diffraction pattern on to a high-resolution single electron sensitive detector. Temporal diagnostics including an RF TDC and THz deflector are included along with a spectrometer at the end of this line to measure beam energy.
Paper: TUPM021
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM021
About: Received: 23 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM026
Advanced beam tuning and beam measurements techniques in the CLEAR facility
1216
The CLEAR (CERN Linear Electron Accelerator for Research) facility delivers to a wide user community a 200 MeV electron beam with highly flexible parameters. Running conditions range from single-bunch to multi-bunch operation, with bunch charges from 10 pC to 1 nC, bunch durations from 100 fs to tens of ps, and includes tunable momentum (30 MeV/c to 220 MeV/c). Such a variety of beam conditions poses a challenge to the beam instrumentation and to the beam measurements and tuning techniques, even more so given that quite often a rapid switch from one set of conditions to a very different one is required. In this paper we present several examples of the techniques developed in CLEAR for this purpose and discuss their advantages and limitations. Examples include emittance measurements and phase space reconstruction procedures by quadrupole scans and beam based alignment methods.
Paper: TUPM026
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM026
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM029
Development of photo injector employing Yb fiber laser for stimulus super-radiant THz FEL
1224
THz wave is wonderful prove for materials. Additionally new nonlinear phenomena are expected in spintronic devices if the peak electromagnetic field is greatly higher than 10 MV/cm (3.3 T/cm). Although coherent transition radiation from short bunches is intense, it is very difficult to exceed 10 MV/cm. However we found a possibility of which oscillator FEL reaches ~100 MV/cm employing a pre-bunched configuration.* On a test accelerator (t-ACTS), we are going to introduce a photo-cathode to increase the bunch charge and synchronize with round-trip frequency of an FEL optical resonator. Currently t-ACTS supplies a bunch-charge of 5 pC, whereas the goal is to increase it more than 50 pC for the pre-bunched FEL. Since the intensity of coherent radiation is basically proportional to the square of the charge per bunch, increase of the bunch charge is much effective. The laser system includes a Yb fiber laser oscillator (wavelength: 1047 nm), a multi-pass amplifier, and a fourth harmonic generation (262 nm). A target synchronization accuracy is within 1 deg at 2856 MHz. The assembly of the oscillator has almost completed, and a work for synchronization with RF is on the way.
Paper: TUPM029
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM029
About: Received: 24 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM030
Analysis of laser-electron-radiation interaction in laser modulators for three SSMB scenarios
1227
Recent studies explored a novel storage ring light source using steady-state microbunching (SSMB). Existing investigations predominantly focused on single-particle and pure-optics phenomena. Many SSMB schemes employ laser modulators, comprising an undulator and copropagating laser beam, to manipulate electron longitudinal bunch length. Electron bunch traversing the undulator emits coherent undulator radiation near the resonant wavelength. Laser beams may form a closed path to become a laser enhancement cavity. We developed a model* analyzing laser-electron-radiation interactions in laser modulator cavities, considering mirror-induced losses, externally injected laser power compensation, and coherent undulator radiation dynamics on multiple turns. Our approach integrates beamline transfer matrices with a low-gain FEL oscillator model, enabling quick estimation of the dynamic effects. In this work we examine three SSMB scenarios, amplifier, frequency-beating, and harmonic, accounting for laser-electron-radiation interactions. Under preliminary design parameters, our analysis suggests feasibility for the three scenarios. A potential self-seeding SSMB scheme is also investigated.
Paper: TUPM030
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM030
About: Received: 23 May 2025 — Revised: 29 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
TUPM032
Cherenkov waveguide design for THz production at the EuXFEL
1235
The EuXFEL R&D project, STERN, aims to provide X-ray users with an accelerator-based THz source synchronized with the X-ray repetition rate. The main proposed THz generation method consists of electron beam wakefield excitation in Cherenkov waveguides. This work focuses on the design of a copper block that holds an array of waveguides to cover the radiation spectrum spanning from 300 GHz to 30 THz. These will include a variety of lengths and dielectric layer thicknesses to vary the spectral contents of the excited TM modes. Additionally, driving the wakefield generation process with an off-axis electron beam causes the excitation of HE modes, which are of great interest to the user community and add to the spectral content of the THz pulse. To further increase pulse energy, the implementation of radiation incouplers is analyzed, demonstrating the potential for capturing the electron beams self-field completely. Such wakefield structures offer a novel option for delivering versatile THz sources tailored to next-generation pump-probe experiments.
Paper: TUPM032
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM032
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM035
Performance of terahertz-wave beamlines at Nihon University's laboratory LEBRA
1239
National Institute of Advanced Industrial Science and Technology (AIST) has collaborated with Nihon University to study generation of high-intensity terahertz waves using coherent radiations at the Laboratory for Electron Beam Research and Application (LEBRA) at Nihon University. In a straight section for parametric X-ray (PXR) generation, developments of various types of coherent radiation sources and a study of superimposed coherent radiation using a ring-type resonator have been conducted. Coherent edge radiation (CER) generated in the downstream bending magnet is transported to an experimental room using the PXR beamline and is used for spectroscopic measurements and imaging experiments in an acrylic box filled with dry air. In a straight section for an infrared free-electron laser (FEL), CER generated by a downstream bending magnet during FEL oscillations is extracted from an FEL resonator by a toroidal mirror with a hole.* The extracted CER is reflected by a sapphire substrate coated with Indium-tin oxide and transported to the room using an FEL beamline. In this presentation, the status of the two THz beamlines at Nihon University's laboratory LEBRA will be described.
Paper: TUPM035
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM035
About: Received: 26 May 2025 — Revised: 31 May 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
TUPM054
Progress towards kick and cancel injection for Diamond-II
1270
With the aim of maintaining transparent and efficient injection during top-up, a kick-and-cancel injection scheme has been developed for Diamond-II. In this, stripline kickers are used with 3 ns pulses to deflect individual bunches, with the stored bunch receiving two kicks separated by 180 degrees phase advance to leave it on-axis and the injected bunch timed to arrive at the second kick. In this paper we present progress with the hardware design and recent prototyping results, alongside updates to the simulations.
Paper: TUPM054
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM054
About: Received: 19 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM086
Simulation study of beam-driven plasma wakefield experiments on CLARA
1353
The Compact Linear Accelerator for Research and Applications (CLARA) is an electron test facility capable of delivering tunable 250 MeV electron beams with up to 250 pC charge to the Full Energy Beam Exploitation (FEBE) experimental area . In this study, we investigate the feasibility of conducting beam-driven plasma wakefield acceleration (PWFA) experiments using the CLARA beam and experimental area. We present simulations of various potential experiments, considering the baseline and R&D beam parameters expected to be delivered to the FEBE experimental chambers*. Our findings highlight the potential for CLARA to support advanced PWFA research, with detailed analysis of beam dynamics and experimental configurations.
Paper: TUPM086
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM086
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM087
A high-efficiency dielectric wakefield energy booster for CLARA
1357
Structure-based wakefield acceleration, using dielectric-lined or corrugated waveguides, is a novel acceleration method currently being explored by several research groups globally. This technology facilitates the transfer of energy from a high-charge drive beam to a lower-charge main bunch with high accelerating gradients. In this study, we propose an energy booster for the Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury Laboratory, utilising dielectric wakefield acceleration (DWA). Our simulation study optimises the drive beam and structure to achieve maximal energy efficiency across varying main beam energies, enabling the delivery of a main beam with adjustable charge and final energy. Additionally, we have considered the stability of both the accelerated and drive beams, selecting the geometry and layout of accelerating structures to maximise accelerated beam quality and mitigate the development of beam breakup instability in the drive beam
Paper: TUPM087
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM087
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM089
Twin-bunch modelling in linear accelerators for plasma wakefield acceleration
1361
Twin electron bunches accelerated by high-energy linacs are attracting increasing interest especially in twin free-electron laser (FEL) pulse generation and beam-driven plasma wakefield acceleration (PWFA) studies. High-energy linacs may benefit from plasma accelerators, where a trailing bunch is accelerated in GV/m fields in a plasma wave driven by the leading bunch. This could facilitate high-energy physics, as well as greatly increase the available photon energy range of existing FELs without increasing the footprint. Here, initial analytical studies of twin-bunch generation in FLASH accelerator are carried out. With the initial beam longitudinal phase space properly tuned by temporally shaping the photocathode laser, together with optimizing linac settings, high-quality twin electron bunches with tunable delay and simultaneous bunch shaping can be generated, which is essential for energy-efficient PWFA with low energy spread.
Paper: TUPM089
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM089
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM092
Design studies on a kHz–MHz repetition rate pulsed muon source based on electron accelerator
1372
Certain types of muon experiments, such as muon spin rotation techniques and muon lifetime measurements, require beams with repetition rates around 50 kHz for optimal statistical performance. However, existing facilities are limited to pulsed beams operating at 25-50 Hz or continuous beams, both constrained by the time structure of proton drivers. Despite ongoing efforts to optimize these proton time structures, significant limitations in flexibility persist. This work introduces an alternative approach to muon production using high-repetition-rate (kHz-MHz) electron beams generated by superconducting linacs at XFEL facilities. This method provides unique temporal characteristics, promising substantial improvements in beam precision, flexibility, and experimental efficiency. We present comprehensive particle tracking simulations for the design of a surface muon beamline and detailed Monte Carlo studies to optimize target materials and geometries. The results underscore the potential of electron-driven muon sources to complement muon-based fundamental and applied physics research while extending the capabilities of current and future XFEL facilities.
Paper: TUPM092
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM092
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
TUPM096
Development of an achromatic spectrometer for a laser-wakefield-accelerator experiment
1383
The large gradients of plasma-wakefield accelerators promise to shorten accelerators and reduce their financial and environmental costs. For such accelerators, a key challenge is the transport of beams with high divergence and energy spread. Achromatic optics is a potential solution that would allow staging of plasma accelerators without beam-quality degradation. For this, a nonlinear plasma lens\* is being developped within the SPARTA\*\* project. As a first application of this lens, we aim to implement an achromatic spectrometer for electron bunches produced by a laser-wakefield accelerator. We report on progress in designing such an experiment.
Paper: TUPM096
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM096
About: Received: 16 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
TUPM107
Preliminary studies for a high gradient 6GeV injector linac for EBS
1399
The ESRF mid-term plan for the upgrade of the injection complex foresees a full energy linac option. Given the space limitations of the site, compactness is a strong design constraint and high gradient technology is a potential candidate to fulfill this goal. Beam dynamics simulations have been performed for several different accelerating structures in the S-, C- and X-band frequencies to define the best candidate.
Paper: TUPM107
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM107
About: Received: 23 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
TUPM113
Beam results for the new super-conducting booster at Jefferson Lab
1403
The performance results of a new super-conducting booster for the CEBAF injector at Jefferson Lab, could be of interest for other similar electron injectors. A recent addition of this new booster has provided us the ability to achieve a more adiabatic acceleration and therefore an improvement to the beam dynamics and beam brightness. It has also simplified the design and operation of the section of the injector responsible for accelerating the electron beam from a few hundred keV to several MeV (typically 6.7 MeV). The addition of the new booster was part of an upgrade to the CEBAF injector to improve the beam quality for future physics experiments with high sensitivity to beam quality. The booster consists of two cavities: a 2-cell cavity followed by a 7-cell cavity. This combination allows for a wide range of input electron beam energies, from 130 keV to more than 300 keV. In fact, during the last year, the booster was successfully operated with 140,180, and 200 keV input beam energies as the electron gun was being upgraded. This paper describes the new booster, presents beam optics data results from different beam studies, commissioning, and the physics quality beam operation.
Paper: TUPM113
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM113
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPM114
An extraction scheme for future CEBAF FFA based energy upgrade
1407
Jefferson lab is considering an energy increase from current 12 GeV to 22 GeV for its CEBAF accelerator. This will be accomplished by recirculating 5-6 additional turns through two parallel CEBAF LINACs using an FFA arc at each end of the racetrack. The total recirculation turns would be 10 times, the first four turns use present conventional arcs to make the 180-degree bends from one LINAC to the other. However, the last 5-6 turns will all share a single beam line inside two FFA arcs. This reduces the footprint and the cost of the project significantly. On the other hand, having the trajectories of last 5-6 recirculating beams close to each other makes it challenging to extract beams from different passes with different energies. In this paper we will explain our present extraction system for 12 GeV, our challenges and limitations, and a possible extraction solution for the 22 GeV upgrade with the goal of extracting beam at different turns/energies to different experimental halls.
Paper: TUPM114
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM114
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
TUPM115
Simulation and developmental status for generation and detection of THz using coherent transition radiation technique in Delhi Light Source
1411
THz technology being a highly growing and potent field, finds use in a wide range of research applications. Delhi Light Source (DLS) at IUAC, New Delhi is at final stage of commissioning to produce intense and coherent THz radiation based on pre-bunched Free Electron Laser principle. As an addition to the narrowband undulator radiation, broadband Coherent Transition Radiation (CTR) will also be produced by passing femtosecond electron beam bunches through an Al foil . To generate the electron bunches with multi-micro bunch structure from the RF photo cathode gun, a state of the art femtosecond fiber laser system has been developed in collaboration with KEK, Japan. The generated electron beam bunches with energy up to 8 MeV is expected to produce CTR maximum up to few microjoule of energy. The multi-micro bunch structure increases the average CTR power. This paper reports the simulation results of the CTR showing the power, angular and frequency distribution produced from DLS facility. The schematic design and developmental status of DLS for generation and detection of THz CTR are also discussed.
Paper: TUPM115
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM115
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
TUPS003
Beamline to inject laser plasma accelerated electrons to a quasi-isochronous compact storage ring
1415
Laser plasma accelerators (LPAs) can produce high-energy electron bunches from short distances. Successfully coupling these sources with dedicated compact storage rings tuned to quasi-isochronous conditions would demonstrate the capture and storage of ultra-short electron bunches in a circular accelerator. Electron bunches generated from LPAs can have a correlated distribution in longitudinal phase space: a chirp, as well as comparably large angular divergence and energy spread. We, therefore, design a flexible beamline that can transport ultrashort bunches with large angular and energy spread to a ring. We have used the accelerator design programs OPA and MAD8 to build up optical model of a beamline. The line is composed of focusing and dispersion matching sections. A set of small angle bending magnets counteracts the dispersion created by injection septum of the storage ring and provides quasi-isochronous bunch transfer with a flexible value of longitudinal dispersion (R56).
Paper: TUPS003
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS003
About: Received: 24 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
TUPS005
Developing expectations for AWAKE with simulations
1419
The AWAKE experiment at CERN makes use of a self-modulated proton bunch to excite wakefields and accelerate a witness electron bunch. Run 2c of the experiment will demonstrate stabilization of the wakefield amplitude and control of the witness bunch emittance during injection and acceleration. In this work, we present an overview of the ongoing simulation efforts to support the project as it moves towards controlled acceleration and first particle-physics applications.
Paper: TUPS005
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS005
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
TUPS006
Proton-driven plasma wakefield acceleration for high-energy lepton beams
1422
Future colliders with discovery potential for particle physics rely on increasing the parton centre of mass (pCM) energy, with the recent P5 report calling for a 10 TeV pCM collider. However, the development of such schemes using conventional accelerator technology would result in ever-larger facilities. High-gradient plasma wakefields driven by proton beams allow the transfer of energy to a witness bunch over a short length scale, and so offer a potential method to transform high-energy proton beams into high-energy lepton beams while requiring relatively little additional civil engineering. The application of this concept to a Higgs factory driven by 400 GeV protons was recently proposed*. In the present work, we discuss the ongoing efforts to address the challenges to realising such a scheme**, and possible upgrade paths to particle physics applications beyond a Higgs factory.
Paper: TUPS006
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS006
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPS010
Electron beam scattering in rubidium vapour at AWAKE
1430
The Advanced Wakefield Experiment (AWAKE) at CERN uses bunches from the CERN SPS to develop proton-driven plasma wakefield acceleration. AWAKE Run 2c (starting in 2029) plans for external on-axis injection of a 150 MeV electron witness bunch. The goal is to demonstrate emittance control of multi-GeV accelerated electron beams. Prior to injection, the electron witness bunch may have to traverse rubidium vapour. Since the beam must have the correct beam size and emittance at injection, it is important to quantify the effect of scattering. For this, first-principle estimates and the results from Geant4 simulations are compared with measurements of a ~20 MeV electron beam scattering in 5.5 m of rubidium vapour, showing good agreement. Building on this agreement, Geant4 simulations using the estimated AWAKE Run 2c parameters are performed. These predict that scattering will not increase the electron beam size or emittance
Paper: TUPS010
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS010
About: Received: 31 Mar 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
TUPS017
Study on Ion Bunch Generation Using a Laser Plasma RF Ion Source
1446
The development of high-intensity, high-quality ion sources is essential for advanced applications such as particle beam therapy and nuclear physics experiments. The aim of this study is to integrate the Laser Plasma RF Ion Source (LaPRIS), currently under development, into the cyclotron at the Research Centre for Nuclear Physics (RCNP) in order to accelerate ion bunches with high precision and intensity for advanced applications. LaPRIS can generate laser-plasma in an RF field at the laser focus spot and produce bunches at arbitrary timings. Previous research* has achieved a proton beam with a peak current of 1.2 mA and a bunch width of 5 ns. This allows the charge per bunch to be increased by a factor of 100 compared to conventional systems. This makes it possible to track the beam behavior for each bunch, which has potential applications in high-intensity cyclotron research. The injection into the cyclotron must be matched to the acceptance, so the emittance of the beam bunches is measured under different laser characteristics and target conditions to investigate the beam properties.
Paper: TUPS017
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS017
About: Received: 02 Jun 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPS019
Beam dynamics optimization in high-brightness Photo Injector with various photocathode laser pulse shapes
1454
At PITZ, a comprehensive study is conducted to analyze the factors influencing emittance growth in the European XFEL (EuXFEL) continuous wave (CW) setup. Emittance growth due to space charge effects can be mitigated using advanced photocathode laser pulse shapes. To optimize beam quality, multiobjective optimization studies using ASTRA are performed, focusing not only on minimizing emittance but also on maximizing beam brightness for various laser temporal profiles and dura-tions. The optimization is initially carried out for the CW injector section planned for EuXFEL. The optimized cases are then further tracked through start-to-end (S2E) simulations to evaluate their behavior in the compression stages of EuXFEL. A comparative analysis of gaussian, flattop, ellipsoidal, and inverted parabolic laser profiles is presented, assessing their efficiency not only in terms of emittance but also in 4D and 6D brightness. Finally, the results of the optimized photoinjector setup and the beam properties after the final bunch compression will be presented.
Paper: TUPS019
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS019
About: Received: 06 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPS027
RF power margin for operation with fixed-target in the CERN SPS
1471
The CERN Super Proton Synchrotron (SPS) Radio Frequency (RF) system was upgraded as part of the Large Hadron Collider Injector Upgrade (LIU) project, and now comprises six 200 MHz travelling wave structures, each fed by a separate RF power amplifier. While the upgrade was targeting the peak power for capture and acceleration of the beams for the High Luminosity LHC, it also brought an increase in the available average power for fixed-target beams. The additional power introduced margins which were first probed and exploited in 2024, when the SPS RF system had to be operated at majorly reduced power, during failures that blocked a single power amplifier or accelerating structure. Specific examples from the 2024 run are given, together with the mitigation measures. This contribution summarizes the efforts and results, highlighting in particular the improvements needed for the control of the RF voltage for easier switching to the degraded mode of operation and back, as well as the impact of the impedance of an undriven cavity.
Paper: TUPS027
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS027
About: Received: 27 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
TUPS028
Achievement of LIU longitudinal parameters at the CERN SPS
1475
To prepare the Super Proton Synchrotron (SPS) as an injector for the High Luminosity Large Hadron Collider (HL-LHC), its Radiofrequency (RF) system was majorly upgraded. The 200 MHz travelling wave structures were rearranged, adding two solid-state power amplifiers and a new Low-Level RF (LLRF) system. The increase in RF power and reduction of the beam coupling impedance at the fundamental frequency were designed for capture and acceleration of four trains of 72 bunches spaced by 25 ns at an intensity of 2.3e11 protons per bunch with bunch lengths of 1.65 ns ±10% at SPS extraction. These beam parameters have first been demonstrated in 2024 after careful optimisation of all the main longitudinal settings: voltage program at fundamental and higher harmonics, interplay of one turn-delay feedback, feedforward and longitudinal damper, as well as controlled emittance blow-up. This contribution details the achieved beam parameters and the conditions that allowed them, along with the encountered limitations.
Paper: TUPS028
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS028
About: Received: 26 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPS046
Study on the time changes of the proton beam passing current from the ion source to the RFQ at J-PARC LINAC
1527
Currently, in the J-PARC linac, beam commissioning between the ion source and RFQ mainly involves adjusting the extraction voltage of the ion source and the two solenoid magnets in the Low Energy Beam Transport line (LEBT) installed between the ion source and the RFQ. These parameters are determined to maximize the measured beam current at the current monitor (SCT) downstream of the RFQ. Previously, the SCT used as a reference had measured the beam current by cutting out a part of the macro bunch. However, to further improve the beam quality, we adjusted LEBT parameters using the newly measured method, which is an integrated whole macro bunch signal. The optimum value obtained by the new method differed from the previous. Therefore, to investigate the cause, we saved all the beam current waveforms of the SCT for reference and compared the ion sources and LEBT parameters of each. As a result, the current of the beam that passed through the RFQ changed over time within the macro bunch for certain ion source and LEBT parameter settings. In this presentation, we will introduce the above study results and discuss the cause of the temporal changes in beam current.
Paper: TUPS046
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS046
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPS055
Simulations study of transverse wakefields in a dielectric wakefield acceleration scheme
1556
Novel acceleration schemes aim to address the need for higher acceleration gradients which enable to minimise the size and costs of particle accelerators. One of these novel accelerator schemes is the dielectric wakefield acceleration (DWA), where an electron bunch is accelerated by the longitudinal wakefields generated within a dielectric lined waveguide by a leading drive bunch with higher charge. The advantages of this novel acceleration method include high accelerating field strength, the simplicity of its structure and the stability of the wakefield generated which is synchronous with the electron bunch. However, the drive bunch propagation length, and hence the achievable energy gain, is limited by the effect of the transverse wakefields. These fields deflect the bunch towards the dielectric, leading to charge losses, a phenomenon commonly referred to as beam break-up (BBU) instability. This study uses simulations to investigate the transverse wakefields and their impact on the beam dynamics in a DWA scheme with drive and witness (main) bunches. The findings will be further explored experimentally at the CLARA facility in Daresbury Laboratory.
Paper: TUPS055
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS055
About: Received: 23 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPS110
Implementation of novel acceleration functionality in BDSIM
1601
Beam Delivery Simulation (BDSIM) is a Geant4 based accelerator tracking code which includes interactions of particles with material. BDSIM has become an important code in the accelerator community to simulate beam lines. Since laser and beam driven plasma wakefield acceleration (LWFA/PWFA) is a promising acceleration method we found it important to include related capability in BDSIM. This requires the addition of new beamline elements that are commonly used in plasma acceleration experiments. A gas volume where the LWFA/PWFA takes place and a beam mask to create a separate drive beam and a witness beam. In the former, the beam interacts with gas so ideal gas calculations are required to input the gas properties. Biasing can specifically be applied to the gas material in those elements. Simulating the interactions between the beam and a plasma is not done in BDSIM. An external software is used to compute the fields and the particles data. BDSIM can now read the output HDF5 files to reconstruct the fields inside the gas capillary or use the particle data as a bunch definition for the beginning of a beamline. Some results explaining how to make a LWFA/PWFA simulation are presented.
Paper: TUPS110
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS110
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPS111
Optical and laser systems for the AWAKE run 2C experiment
1604
In the AWAKE Run 2c experiment, two electron beams are injected into two separate rubidium (Rb) vapour sources. The first electron beam initiates the self-modulation of a proton bunch in the first vapour source, while the second electron beam serves as a witness beam for plasma wakefield acceleration with low energy spread in the second vapour source. This setup requires the precise spatio-temporal delivery of four laser beams: two deep UV beams that generate the electron beams with a relative timing jitter well below 100 fs, and two near-IR beams that ionize efficiently the Rb vapour sources. The UV pulses are generated by an established Yb laser system, capable of producing 400 uJ, 0.2-10 ps pulses at 257 nm with high reliability (<0.1% RMS energy fluctuation), and enables emittance optimization via spatial beam shaping. The same system is used for both electron sources, utilizing a partial reflector to split the beam and account for differing photocathode yields. For the Rb ionizing pulses, which are directed into the vapour sources in a counter-propagating geometry, the pulses from the AWAKE Ti:Sapphire laser system are transported using a series of vacuum relay telescopes.
Paper: TUPS111
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS111
About: Received: 15 Apr 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
TUPS115
Optimization of the driver energy deposition in plasma wakefield acceleration simulations by varying transverse offset of sextupole magnets
1611
Plasma Wakefield Acceleration (PWFA) is a method of accelerating charged particles using a plasma. It has the potential to produce exceptionally large accelerating gradients on the order of 10’s of GeV/m. The FACET-II test facility accelerates pairs of 10 GeV electron bunches to study the PWFA process—a drive bunch to produce a wake in the plasma in a lithium-ion oven, and a witness bunch to be accelerated by PWFA. By using arrangements of sextupole magnets, it is possible to alter the chromaticity and other energy-dependent properties of the beams prior to their entry into the plasma. The purpose of this study was to determine how the transverse offsets of the sextupole magnets could be optimized to increase the amount of energy deposited into the plasma by the drive bunch as this energy deposition is critical to maximising the efficiency of PWFA. To achieve this, a simulation of the FACET-II beamline was performed with sextupole offsets as adjustable parameters in a Bayesian Optimization procedure. The results demonstrate the value of using beam simulations as guides to improve the PWFA process, thereby reducing the need to perform costly experiments at the FACET-II facility.
Paper: TUPS115
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS115
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
TUPS136
Characterization of the energy spectrum of a 30-MeV cyclotron-based quasi-monoenergetic neutron beam using a time-of-flight spectrometer
1633
We conducted time-of-flight (TOF) measurements to characterize the spectrum of a quasi-monoenergetic neutron beam driven by a 30-MeV proton cyclotron at the National Atomic Research Institute in Taiwan*. Neutrons were produced by irradiating 30-MeV protons onto a 1-mm-thick beryllium target. The developed TOF spectrometer comprised two 2-inch EJ-309 organic scintillators positioned 200 mm from the neutron beam port to detect gamma rays emitted from the target, and a 3-inch EJ-309 scintillator placed at a flight distance of 2940 mm to measure neutrons. As the signals of gamma-ray bursts triggered TOF measurements at an RF frequency of 73.13 MHz, repetitive distributions of coincidence events between gamma-ray and neutron-related signals were observed, resulting in an effective time window of 13.67 ns for measuring neutrons in the energy range of 16.19–30 MeV. The measured neutron spectrum exhibited a peak at 26 MeV, verifying the simulated spectrum obtained from an MCNP Monte Carlo model. Additionally, we developed a fast-timing scintillator module that measured the proton bunch duration as 0.97 ns, enabling accurate estimation of the energy resolution of the neutron spectrum.
Paper: TUPS136
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS136
About: Received: 24 May 2025 — Revised: 31 May 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEAN1
Measurement techniques using the electron beam profile scanner at the Fermilab Main Injector
1670
This work presents techniques for non-invasive transverse profile measurements of high-intensity proton beams using an Electron Beam Profile Scanner (EBPS). The EBPS utilizes low-energy electrons as a probe to analyze the transverse size of proton beams, allowing for potential analysis on a single-bunch basis. Recent upgrades to the Fermilab Main Injector have enhanced beam power on target to 1 MW, with future developments targeting 2 MW. The higher beam power has increased the demand for non-invasive diagnostics, as invasive methods can disrupt operations. The techniques presented include 1) the slow scan technique, which serves as a proof of concept for the probe beam, 2) the one-shot scan technique for measuring horizontal beam profiles, and 3) the raster scan technique for analyzing horizontal beam profiles as a function of the longitudinal distribution of the beam. The profiles obtained will be crucial for studying and understanding instabilities in high-power, high-intensity proton beams. This will contribute to optimizing the operation of high-power proton accelerators by minimizing beam loss, activation, and damage to both the diagnostics and the accelerator components.
Paper: WEAN1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEAN1
About: Received: 01 Jun 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEYN1
Ultrafast visualization of quasi-three-dimensional electric field of relativistic electron beam
1687
EM (electromagnetic) field around a relativistically ac-celerated charged particle is known to be squeezed longi-tudinally. This behavior is called the Lorentz contraction, and no inconsistent phenomena have been found. How-ever, an experiment has not directly confirmed the Lo-rentz contraction of the EM field. The first direct observa-tion of the Lorentz contraction of the EM field was recent-ly performed using an electron linac at the University of Osaka[*]. The electric (Coulomb) field around a sub-picosecond electron beam with an energy of 35 MeV was measured by an electro-optic (EO) sampling method. A single-shot electric field measurement system was devel-oped using EO sampling and an echelon mirror. A modu-lated laser light due to the Pockels effect was decoded into a spatio-temporal image of the electric field, and the Lo-rentz contraction was directly confirmed. This ultrafast measurement technique can help longitudinal diagnostics of a charged particle beam. This presentation will report ultrafast visualization of quasi-three-dimensional (trans-verse and longitudinal) electric fields of a relativistic elec-tron beam and their evolutions.
Paper: WEYN1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEYN1
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEBD2
Active 3rd harmonic RF system for ALBA
1695
ALBA is a 3rd generation synchrotron light source located in Barcelona, Spain. The circumference is 268.8 meters and electrons are stored at 3 GeV. In the framework of the upgrade towards the 4th generation light source ALBA II, an active 3rd harmonic RF system at 1.5 GHz is foreseen to increase the Touschek lifetime component. The system will be installed and available for operation in the current machine, which will allow to gather experience before the upgrade. Four normal conducting HOM damped harmonic cavities will be placed in the storage ring, each of it including a complete WR650 waveguide system with circulator and load, a 20 kW high power SSPA amplifier and a Low Level RF control system. We are presenting in this contribution the complete design of the active harmonic RF system for ALBA and the expected performance during operation.
Paper: WEBD2
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEBD2
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
WEZN2
LCLS-II commissioning and operation with high-repetition-rate CW FELs
1710
LCLS-II first stage commissioning is completed in the summer of 2023, with demonstration of 93 kHz electron beam and 1 kHz FELs using the superconducting CW linac. Operation-based electron beam and FEL commissioning has been continued with the goal of ramping up beam rate, improving the FEL performance, and developing advanced FEL operation modes. We started 33 kHz x-ray FELs to user experiments from 2025. The latest machine performance, commissioning challenges, and next-step plan will be discussed in this paper
Paper: WEZN2
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEZN2
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
WECN1
SLS 2.0 storage ring commissioning
1714
The SLS consists of a 100MeV linac, a 2.7GeV booster synchrotron with 9nm horizontal emittance and the storage ring (SR). The old 12-TBA SR with 5nm horizontal emittance operating at 2.4GeV was turned off in 09/2023 after 22 years of successful user operation. In course of the SLS 2.0 upgrade project the 288m circumference SR has been replaced by a 2.7GeV 12-fold 7-bend achromat lattice with a considerably reduced horizontal emittance of 150pm, while keeping the injector complex mostly unchanged. After recommissioning of the injector chain at the end of 2024 SR commissioning starts in January 2025 with some challenges ahead. A reverse bend design has been implemented to achieve the lowest possible emittance with the given small footprint of the SR leading to a very dense magnet arrangement. All bending and combined function magnets which largely determine the novel optics are permanent magnets which will guide the beam through NEG coated vacuum tubes with an aperture of only 18mm. Due to excellent beam diagnostics and optics adjustment capabilities combined with an advanced remote girder alignment system we expect to achieve the performance goals of the storage ring by mid 2025.
Paper: WECN1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WECN1
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
WEFN1
Experimental demonstration of transient-beam-loading compensation using new digital LLRF system at the Photon Factory storage ring
1722
In ultra-low-emittance synchrotron light sources, the bunch-lengthening technique is useful to mitigate harmful effects due to the intrabeam scattering. The perfomacne of the bunch lengthening can be degraded by the transient beam loading (TBL) effect induced in the cavities. To mitigate the TBL effect, we proposed a TBL compensation technique using a wide-band longitudinal kicker cavity. In this presentation, we report the result of the experimental demonstration of the TBL compensation performed at the KEK PF 2.5 GeV ring. In this experiment, the fill pattern of the electron bunches were customized to enlarge the phase variation of electron bunches induced by the TBL effect. The fundamental cavities and newly developed digital low-level RF (DLLRF) system were used for the experiment. The DLLRF enables the TBL compensation by an arbitrary feedforward pattern of the cavity voltage modulation that is synchronized with the revolution frequency. Although the bandwidth of the fundamental cavity is limited, the variation of the cavity voltage and bunch phase induced by the TBL effect was reasonably mitigated by applying sinusoidal wave modulation of the cavity voltage.
Paper: WEFN1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEFN1
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
WEPB008
Higher order mode power in superconducting cavities of SuperKEKB with high current operation
1734
SuperKEKB is a high-current machine for high-luminosity.Eight higher order mode (HOM) damped single-cell superconducting cavities accelerated an electron beam in the main ring since KEKB. A strong dependence of the absorbed power of the ferrite HOM dampers on the number of bunches was observed in 2022 operation. One of the reasons for this is thought to be a build-up effect of some parts of the HOM caused by narrow bunch spacing. It was found in the last operation that this problem has an individual difference for each cavity. In particular, TM011 can propagate on the LBP side, and the frequency is quite close to an integer multiple of the RF frequency, the build-up effect is remarkable. As the accelerator is expected to reach its design current in the future, the HOM power will also increase and ferrite HOM dampers will have to cope with the increasing HOM power resulting from the build-up. This report provides an overview of the status of the superconducting cavity HOMs last operation in 2023-2024 and a countermeasure plan for the future.
Paper: WEPB008
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB008
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPB026
Magnetic design of the cSTART magnets
1788
The KIT project cSTART (compact STorage ring for Accelerator Research and Technology) aims to store ultra-short electron bunches in a very-large-acceptance compact storage ring. The magnetic lattice of the storage ring is laid out for a variety of beam optics, including ultra-low positive and negative alpha as well as isochronous optics. These put high demands on the magnet quality and alignment. The spatial constraints for the storage ring impose further challenges on the magnet design. In this contribution, we give an overview of both the challenges and solutions for the cSTART storage ring magnet design.
Paper: WEPB026
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB026
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPB063
Study of a fast kicker magnet for beam scanning in VHEE therapy
1887
Over the past two decades, very high-energy electron (VHEE) beams ranging from 50 to 250 MeV have been explored as a potential technology for treating deep-seated tumors. FLASH radiation therapy (FLASH-RT) delivers ultra-high dose rates (UHDR) within a few milliseconds, suggests the possibility of enhanced cancer cell lethality while reducing damage to normal tissues. Combining VHEE with FLASH-RT shows potential in cancer treatment. Pencil beam scanning (PBS) is an important technique in VHEE radiotherapy. However, the ultra-short treatment times required by FLASH-RT (0.1–1 second) imply that the scanning speed must be very high, necessitating linear accelerators (LINACs) with a repetition rate significantly higher than 1 kHz, which is challenging to achieve. A fast kicker magnet, consisting of a one-turn coil and a pulsed power supply, can generate a magnetic field with rapid rise and fall times. A LINAC can produce an electron beam with a variable bunch train of 0.1-1 μs. By deflecting the bunch train using a fast kicker magnet, it is possible to generate a line scan that approximates the functionality of pencil beam scanning.
Paper: WEPB063
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB063
About: Received: 07 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPB076
RF design for optimal high-gradient performance of a four-quadrant structure for the ASTERIX project
1904
The ASTERIX project, funded by CSN5 and proposed at INFN-LNF, aims to demonstrate a practical, meter-long X-band RF structure for linear accelerators made of hard copper and divided into four quadrants. The prototypes will be constructed by TIG welding. In the first year of the feasibility study, we will design the RF cavities for two full structures working at single-bunch and multi-bunch operation. In this paper, structures operating at single-bunch mode for ASTERIX are numerically studied. The surface field enhancements of the quadrant-type accelerating structures are the most challenging issue to be resolved. The geometry near the gap between four quadrants is carefully optimized and obtain low surface field while maintaining high RF performance.
Paper: WEPB076
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB076
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPM010
Beam-based beam-beam benchmarking and correction
1968
Optics studies in the LHC are generally performed on low-intensity, non-colliding beams. Understanding the optics perturbation from beam-beam effects however, is of significant interest. This was particularly true for the LHC in 2024, where the 3Qy resonance driven by the long-range beam-beam (LRBB) contributed to breaking of the collimator hierarchy, limiting beta* reach and luminosity. By performing optics measurements on a low-intensity bunch in collision with a nominal train, it has been possible for the first time to directly measure the optics perturbation from LRBB in the LHC. Benchmarking of the beta-beat and resonance driving terms against simulation shows good agreement. Based on these models, it was possible to find corrections for the LRBB driven 3Qy resonance using the skew-sextupole correctors present in the LHC.
Paper: WEPM010
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM010
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM015
Optics function determination using luminosity data
1984
Determining the betatronic waist shift and the $\beta^*$ at the interaction points through K-modulation in the Large Hadron Collider presents considerable challenges. This paper introduces a novel method for the measurement of these quantities, based on luminosity measurements and the van der Meer technique for reconstructing transverse bunch profiles. The strategy involves colliding multiple bunches with distinct emittances, performing emittance scans, and subsequently shifting the collision point along the longitudinal plane via RF cogging. This shows promising potential to reduce uncertainties in the optics parameters at the interaction point and to obtain measurements of the absolute beam emittance. The first measurement using this technique was carried out at the Large Hadron Collider, with the analysis and findings discussed in detail.
Paper: WEPM015
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM015
About: Received: 23 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM016
Benchmarking of LHC beam intensity dependent transverse tune corrections at injection energy
1988
Observations of betatron tune evolution during LHC beam injection have revealed a significant tune error, strongly correlated with beam intensity. This finding highlights limitations in the existing feedforward corrections based on Laslett coefficients. A dedicated machine development study was conducted to refine intensity-dependent tune corrections. Utilizing high-precision, per-bunch tune measurements facilitated by the LHC transverse feedback system, the study characterized tune shifts under varying intensities and beam conditions. The results uncovered pronounced discrepancies between horizontal and vertical planes, which deviate from predictions made by the current correction model. These insights provide a critical foundation for improving the accuracy of intensity-dependent tune adjustments, impacting operational stability and efficiency, in particular when considering future operation of the high-luminosity LHC.
Paper: WEPM016
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM016
About: Received: 23 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPM018
Optimizing beam-beam beta-beating for luminosity enhancement at the LHC
1992
The optimization of LHC operation is focused on achieving the highest possible integrated luminosity to maximize experimental data collection. Given the limitations of current detector systems, maintaining a constant level of integrated luminosity has become more critical than achieving a high peak luminosity. Techniques such as beta-leveling and separation levelling have already been implemented to adjust luminosity and enhance operational efficiency. This study describes how the beam-beam beta-beating effects propagating between the multiple experimental interaction points can serve as an additional mechanism to further increase the total integrated luminosity. The operational solutions and impact on performance will be shown for both the current LHC and its future High Luminosity upgrade.
Paper: WEPM018
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM018
About: Received: 23 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPM024
BESSY III intra-beam scattering and touschek lifetime calculations
2008
The 4th generation synchrotron light source, BESSY III, is expected to enable high-impact applications for users in life science, material science, energy and catalysis materials, and more. Currently in its Conceptual Design Report (CDR) phase, the feasibility of BESSY III's ambitious parameter range necessitates a thorough assessment of "collective effects". These phenomena can either compromise beam stability or degrade beam quality, potentially hindering the expected performance. In this work, we present recent estimations of the Intra Beam Scattering (IBS) and Touschek lifetime for the BESSY III lattice. The IBS leads to an increase in longitudinal and transverse emittances, it is described through the IBS growth rates and equilibrium emittances. Both quantities were computed with the ibsEmittance module from elegant and a newly implemented module in Xsuite. The Touschek effect induces beam losses along the storage ring resulting in a shorter beam lifetime. Its effect was computed using pyAT. Finally, the impact of different emittance coupling factors is studied to mitigate both effects, laying the first stone for future studies with higher-harmonic cavities.
Paper: WEPM024
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM024
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM031
Simulation-based optimization of the injection of ultrashort non-Gaussian electron beams into a storage ring
2028
The compact STorage ring for Accelerator Research and Technology (cSTART) project at the Karlsruhe Institute of Technology (KIT, Germany) aims to explore non-equilibrium electron beam dynamics and injection of laser-plasma accelerator (LPA) bunches. The Very Large Acceptance compact Storage Ring (VLA-cSR) is also filled by a second injector that delivers ultra-short bunches from the Ferninfrarot Linac- Und Test-Experiment (FLUTE). Injection from FLUTE into the VLA-cSR is achieved via a complex 3D injection line featuring tilted deflections, negative dispersion, and extreme compression to femtosecond bunch lengths. From this transport, the bunch develops pronounced non-Gaussian tails; nevertheless, near the injection point, it is crucial to ensure matching to both the dynamic aperture and the periodic solutions of the storage ring dynamics. The 25 quadrupole magnets of the injection line make conventional optimization methods impractical. This contribution discusses the development of the magnet optics to meet these extreme requirements. The optimization task was divided into two parts: longitudinal compression was addressed using a surrogate model, while transverse matching is currently being pursued with Bayesian optimization.
Paper: WEPM031
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM031
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPM033
Energy ramping simulation for TPS booster ring
2036
The Taiwan Photon Source (TPS) booster ring accelerates electron beams from the linear accelerator (lin-ac) output energy of 150 MeV to 3 GeV for storage ring injection. In the event of partial RF station failure in the linac, the available beam energy may be reduced to 100 MeV. Preliminary machine tests have demonstrated multi-turn beam circulation in DC mode and successful acceleration from 127.5 MeV to 3GeV. Beam dynamics simulations using elegant evaluate the effects of dipole field errors, magnet multipole and alignment errors, chamber aperture constraints. Additionally, space charge effects at 100 MeV, due to the low relativistic factor, could lead to incoherent tune shifts, and potential beam loss. This study investigates the feasibility of operating the TPS booster at 100 MeV injection and ramping to 3 GeV with a focus on beam dynamics considerations
Paper: WEPM033
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM033
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM037
Design progress of the booster synchrotron for Siam Photon Source II
2047
The Siam Photon Source II (SPS-II) represents Thailand’s second synchrotron light source, designed to enhance the region’s scientific capabilities by providing high-energy, high-intensity synchrotron light for both academic and industrial research. The SPS-II will be situated in the Eastern Economic Corridor of Innovation (EECi) in Rayong Province. The SPS-II accelerator complex comprises three main parts: a linear accelerator (linac), a 3 GeV booster synchrotron, and a 3 GeV electron storage ring. The booster synchrotron is specifically designed to ramp beam energy to 3 GeV with a repetition rate of 2 Hz. This paper provides the latest update on the design of the booster synchrotron and related ramping studies. The study investigates the impact of magnetic field errors, multipole field imperfections, and alignment tolerances on beam parameters, with particular emphasis on the energy ramping process to ensure efficient and stable accelerator operation.
Paper: WEPM037
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM037
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
WEPM041
Updated single-bunch instability threshold measurements in Diamond
2062
This work presents the results of single-bunch-instability measurements in the Diamond storage ring. A streak camera was used to measure the bunch lengthening with current, whilst transverse multi-bunch feedback (TMBF) was utilised to quantify the charge-dependent betatron tune shifts and the head-tail instability thresholds. The results show that increasing chromaticity can be used to mitigate head-tail instabilities which can allow to accumulate higher charge in a single bunch. Using TMBF to suppress single-bunch instabilities is discussed.
Paper: WEPM041
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM041
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPM044
Analysis of losses and emittance growth in the 2024 LHC run and correlation with Dynamic Aperture
2069
This paper presents observations collected during the LHC operation with proton beams in 2024. In particular, a systematic analysis of the beam and machine parameters along the run reveals that the emittance evolution at the LHC injection plateau and during collisions cannot be fully explained by Intra-Beam scattering, synchrotron radiation and electron cloud effects, thus indicating that some beam dynamics effects are missing in the models. During the collapse of the separation bumps, a significant drop in beam lifetime is observed due to the reduction of Dynamic Aperture as the separation reduces and the machine enters into a beam-beam dominated regime. The correlation of beam lifetime in operation and Dynamic Aperture in simulations is demonstrated. Furthermore, a strong correlation is identified between this lifetime reduction and the population of non-Gaussian tails in the transverse beam profiles. The paper also includes the observation of high-frequency power supply ripple in the beam spectrum.
Paper: WEPM044
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM044
About: Received: 29 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPM045
Luminosity modeling of the LHC operation and performance projections for HL-LHC
2073
The LHC luminosity model is a powerful tool for studying the evolution of beam and machine parameters during the LHC operation. The model includes important effects that are present in LHC operation such as Intra-Beam Scattering, synchrotron radiation and burn-off. By comparing model predictions with experimental data, the presence of additional emittance blow-up and intensity loss mechanisms can be identified and then further studied. Using this model for comparing different configurations such as optics, filling schemes and beam types, allows identifying the best strategy to be adopted in operation to maximize integrated luminosity. In this contribution, we show the benchmarking of this model with data from the presently ongoing LHC Run 3, and its application to predicting the integrated luminosity for its future High-Luminosity LHC upgrade.
Paper: WEPM045
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM045
About: Received: 29 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPM046
Optimising multi-turn extraction at CERN using transverse feedback
2077
Initial experimental investigations of transverse beam splitting, carried out at the CERN Proton Synchrotron, have demonstrated that transverse feedback is highly effective in controlling the characteristics of the transversally split beam. The feedback notably improves the intensity distribution among the beamlets and the emittance of the core, which is the portion of the beam remaining near its centre after the resonance-crossing process. The transverse feedback is set in resonance with the horizontal betatron tune while the tune crosses the fourth-order resonance, creating a double-resonance condition. A simple Hamiltonian model has been employed to explore the underlying double-resonance mechanism. This paper thoroughly examines detailed numerical simulations based on a realistic lattice model alongside beam measurements, to identify optimisation strategies for the use of transverse feedback in controlling the properties of split beams.
Paper: WEPM046
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM046
About: Received: 02 Jun 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPM063
Symmetric double-double bend lattice for a potential EUV diffraction limited upgrade of the HLS
2113
NSRL recently proposed a future plan to further upgrade the HLS to an EUV diffraction-limited storage ring, named HLS-III. In this paper, a symmetric double-double bend lattice with long and mid-straight sections is studied as a highly promising design for the HLS-III storage ring. The design achieves an ultra-low natural emittance of 2.82 nm·rad at 800 MeV, while maintaining the current eight straight sections but with significantly reduced beta functions in these straights. By minimizing the fluctuation of resonance driving terms, the nonlinear dynamics optimization yields a large horizontal dynamic aperture of about 40 mm. Additionally, error and intra-beam scattering effects are evaluated.
Paper: WEPM063
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM063
About: Received: 08 Apr 2025 — Revised: 31 May 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPM068
Broadband characterization of the CERN-SPS driving and detuning impedance
2121
The CERN-SPS transverse impedance model plays an important role in predicting beam stability and guiding machine operation. This work advances the benchmarking of the SPS vertical impedance model through experimental investigations of mode-zero instability growth rates and intensity-dependent tune shifts as a function of chromaticity. Building on insights from previous measurement campaigns, this study aims to address persistent discrepancies in the high-frequency domain associated with the real driving component of the effective impedance. The 2024 campaign incorporates growth rate measurements at varied transverse tunes to eliminate potential resonance crossing effects that could artificially enhance the high-frequency mismatch. The imaginary component of the transverse impedance is likewise explored by correlating intensity-dependent tune shifts with chromaticity variations. By combining all measurements and beam dynamics simulation results, the driving and detuning impedance model of key elements will be refined, offering improved predictive capabilities for the current SPS transverse impedance model.
Paper: WEPM068
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM068
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM071
Direct interpretation of coherent synchrotron radiation modeling from the Lienard-Wiechert equation with shielding
2125
Coherent Synchrotron Radiation (CSR) plays a critical role in beam dynamics, significantly influencing beam shape and energy characteristics in particle accelerators. This study investigates the CSR effect through a comprehensive numerical approach, starting from the fundamental Lienard-Wiechert equation and utilizing an explicit, non-approximated methodology to explore beam energy dynamics. This paper focuses on simulating CSR effects in conjunction with the shielding effect from parallel plates, which are crucial in mitigating potential beam energy loss.* By benchmarking results against Saldin's established work **, the study examines wakefield characteristics, particularly the high-peak behavior at small particle separations.
Paper: WEPM071
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM071
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM072
Computational analysis of shielding on the coherent synchrotron radiation generated by a 3D bunch
2129
The analysis and mitigation of collective beam effects, such as coherent synchrotron radiation (CSR), is a significant challenge in the generation of high-brightness beams. To this end, considerable effort has been invested in the development of simulation tools to accurately characterize the CSR generated by a bunch following a curved trajectory. In particular, with codes like LW3D and CoSyR, it is possible to model the CSR wake due to an evolving 3D bunch distribution in free space with minimal approximation. Recently, we have developed a simulation tool that self-consistently characterizes CSR through direct computation of the Liénard–Wiechert fields while accounting for the presence of shielding walls. In this work, we use this method to study the CSR shielding effect on a complex bunch moving through both a single dipole and a bunch compressor, with particular emphasis on the boundaries of validity of 1D theory in predicting the phase space evolution. This work is part of a broad effort to investigate the impact of shielding both theoretically and through a series of planned experiments at the Argonne Wakefield Accelerator (AWA).
Paper: WEPM072
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM072
About: Received: 29 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPM074
Impact of the geometric impedance of collimators on beam stability in FCC-ee
2137
Beam stability in the FCC-ee collider is strongly influenced by transverse and longitudinal beam coupling impedance. Developing a flexible and comprehensive impedance model is crucial for accurately evaluating and mitigating instabilities as machine parameters evolve. This study investigates the effect of the FCC-ee collimation system, identifying it as a dominant source of total machine impedance. Both resistive and geometric contributions are analyzed, with geometric effects found to play a critical role in shaping the overall impedance landscape. Accurately modeling collimators’ geometric impedance is essential for beam stability assessment. Such modeling enables global impedance considerations, accounting for the interplay between different accelerator elements and guiding the definition of critical design parameters.
Paper: WEPM074
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM074
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM075
Beam impedance investigation of the elliptical interconnecting vacuum modules of the LHC and prospect for HL-LHC
2141
In view of ensuring the successful completion of the third operational run of the Large Hadron Collider (LHC) and preparing for the High-Luminosity LHC era, a systematic assessment of the risk of failure of all the vacuum interconnection modules installed in the accelerator is being carried out. This was prompted by a significant pressure rise in 2023, localized near an interconnection module (212 mm inner diameter) caused by a localized impedance-induced heating on the tension spring. This led to degradation and loss of electrical contact of the Radiofrequency (RF) sliding fingers. The studies include the evaluation of the various modules currently present in the LHC, alongside the description of a mitigation strategy. In this paper, we focus on the study of elliptical vacuum modules both from the point of view of electromagnetic simulations and of experimental validation. We report also on the general strategy where the most critical vacuum modules with sliding contact RF fingers, featuring tension springs, will be replaced with upgraded designs to avoid issues and therefore ensure improved reliability under future operational conditions with higher bunch intensities.
Paper: WEPM075
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM075
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPM077
Resistive wall impedance calculations and effects of NEG coated insertion device vacuum pipes for the PF-HLS ring
2149
I show analytical expressions of the longitudinal and transverse impedances of a two-layered circular pipe and their practical expressions at high frequencies derived by using asymptotic expansions of the Bessel functions. These expressions are applied to resistive-wall impedance calculations of NEG-coated insertion-device(ID) pipes for the PF-HLS ring*, which is proposed as a 2.5/5.0 GeV energy switchable ring and can simultaneously provide synchrotron light pulses emitted by electron bunches stored in the ring and by extremely short electron bunches (50 fs in length) injected from the superconducting linac. Both real and imaginary parts of the impedances rise up in high frequency regions depending on the NEG coating thickness. The heating powers of the ID pipes are calculated from the real parts of the longitudinal impedances for the stored electron beam and for the short electron bunches injected from the superconducting linac. The kick factors and the coherent betatron tune shifts due to the ID pipes are calculated from the imaginary parts of the transverse impedances for the stored electron beam. These dependences on the NEG-coating thickness are shown in this presentation.
Paper: WEPM077
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM077
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
WEPM080
Impact of the cSTART impedance on beam dynamics
2160
The combination of a compact storage ring and a laser-plasma accelerator (LPA) can serve as the basis for future compact light sources. One challenge is the large momentum spread (about 2%) of the electron beams delivered by the LPA. To overcome this challenge, a very large acceptance compact storage ring (VLA-cSR) was designed as part of the compact STorage ring for Accelerator Research and Technology (cSTART) project, which will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a versatile source of ultra-short bunches, will serve as an injector for the VLA-cSR to benchmark and emulate LPA-like beams. In a second stage, a laser-plasma accelerator will be used as an injector. The large-momentum spread bunches in non-equilibrium and with charges from 1 pC to 1 nC and lengths from few fs to few ps pose challenges for the beam dynamics simulations. An understanding of the ultra-short bunch dynamics also requires an impedance model up to high frequencies. Here, we present first results on the impact of the machine impedance to the beam dynamics.
Paper: WEPM080
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM080
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPM082
Cavity loops Influence on the single-bunch Instability thresholds of the CERN PS Booster
2168
The CERN Proton Synchrotron Booster (PSB) delivers a wide variety of high-intensity and high-brightness proton beams to several destinations, including operations at the Large Hadron Collider (LHC) and various fixed-target experiments. Following the Long Shutdown 2 (LS2) upgrades, discrepancies between beam measurements and macro-particle simulations were observed, highlighting the need for a deeper understanding of the longitudinal impedance and related effects in the PSB. To address this, longitudinal single-bunch instability studies have been conducted to evaluate the impedance model through the intensity and energy thresholds across different radio-frequency configurations. This contribution presents experimental results that explore instability mechanisms and the effect of the beam loading compensation feedback system. These results are used to benchmark a new cavity loop simulation, which enables more detailed studies of the accelerator impedance.
Paper: WEPM082
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM082
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPM090
The stability diagram for longitudinal coupled instabilities of the ALBA upgrade
2180
The design of the ALBA upgrade forsees the use of an active harmonic cavity system for bunch lengthening. The resulting RF-potential will be a combination of a harmonic and a quartic potential. The corresponding stability diagram will be computed and compared to the stability diagram based on a pure quartic RF-potential. It will be checked if an already existing HOM in the DAMPY cavities and a parasitic mode found in the bellows can be damped with this mechanism. Since the radiation damping of the ALBA upgrade is rather weak the Landau damping is an asset for the stability of the upgrade.
Paper: WEPM090
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM090
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPM091
Estimation of the microwave instability at ALBA
2183
In a collaborative work between ALBA and KEK the computation of the microwave instability threshold of the current ALBA ring was initiated. This analysis involves solving the dispersion relation equation* and conducting simulations using a Vlasov-Fokker-Planck (VFP) solver**. The longitudinal wake fields of geometric origin of all vacuum elements were computed with GdfidL*** using a bunch whose length is at least 5x smaller than the bunch length given by usual 3MV RF-voltage applied at ALBA. The resistive wall contribution was computed at first as longitudinal impedance by IW2D**** to be converted in a second step into wake fields via Fourier transform. The CSR contribution will also be considered. The impact of the 3 types of wakes on the microwave instability will be studied. The microwave instability single bunch threshold will be computed combining the 3 contributions. This work also serves as a preparation of the future evaluation of the microwave instability of the ALBA upgrade, which is expected for 2030.
Paper: WEPM091
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM091
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM092
Investigating ion beam loss mechanisms at the SPS flat bottom
2187
The long injection segment (flat bottom) of the cycle in the Super Proton Synchrotron (SPS) used for filling the Large Hadron Collider (LHC) with Pb ion beams, exhibits strong beam losses and transverse emittance growth. During the 2024 run, large improvements of the beam transmission could be made such that record intensities could be delivered to the LHC. In particular, these improvements were enabled by operational measures such as working point optimization and a numerical compensation scheme for the 50 Hz ripple from the main quadrupole power converters. This paper provides a summary of these improvements, and presents recent advancements in particle tracking simulations of the SPS flat bottom, including effects such as intra-beam scattering and space charge in the presence of tune modulation induced by power converter noise. These simulations are compared with transverse and longitudinal beam measurements. The relative importance of each effect and their estimated impact on the future ion programmes at CERN are discussed.
Paper: WEPM092
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM092
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPM093
A particle-in-cell implementation of intra-beam scattering for Xsuite
2191
Intra-Beam Scattering (IBS) remains one of the primary mechanisms of emittance blow-up and performance degradation in the Large Hadron Collider (LHC) accelerator chain. The phenomenon is particularly relevant following the recent injector upgrades to achieve the high-brightness beams required for the High Luminosity LHC (HL-LHC) era. Traditional IBS models, as those already implemented in Xsuite, rely on the assumption of Gaussian beam distributions. However, observations in the CERN complex indicate the presence of q-Gaussian beam profiles, for which these models do not accurately reproduce IBS effects. To address this limitation, a Particle-In-Cell (PIC) approach was developed that operates independently of distribution assumptions. This methodology behind the PIC approach, and benchmarks against existing models as well as experimental data from the LHC are presented in this contribution. Current limitations are also discussed.
Paper: WEPM093
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM093
About: Received: 22 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM094
Space charge in the GALACTIC Vlasov solver
2195
The GALACTIC Vlasov solver can be used to study the impedance-induced transverse coherent instabilities, considering any longitudinal distribution function, describing the beam with transverse coherent oscillation modes in the frequency domain and ending up with an eigenvalue system to solve. In this paper, the effect of the transverse coherent direct space charge is added, considering a linear RF force and three distribution functions in the longitudinal plane: Water-Bag (or uniform), Air-Bag (or Dirac delta) and Gaussian. These three cases are then compared to the Air-Bag bunch in a Square potential well (ABS) model, which has been often used in the past.
Paper: WEPM094
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM094
About: Received: 21 May 2025 — Revised: 31 May 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPM095
Transverse coherent direct space charge: comparison between several approaches
2199
The proton driver of a future Muon Collider complex is designed to deliver a multi-GeV, short and high-intensity proton bunch to a target in order to maximize the muon yield. In the International Muon Collider Collaboration (IMCC), two high power H- Linac configurations are studied: a 2 MW with a beam energy of 5 GeV, and a 4 MW with a beam energy of 10 GeV. The Linac is followed by an accumulator ring and a compressor ring. With a single bunch intensity of 5.0e14 protons within a transverse emittance of ~15 mm mrad, strong space-charge effects can be expected in these rings. In this framework, different simulation codes used to estimate the transverse coherent space-charge mode frequency shifts in synchrotrons have been compared: BimBim, based on the Circulant Matrix Model (CMM); the Effective impedance method for space-charge; GALACTIC based on the Vlasov equation; the boxcar model for space-charge only; and the ABS model which assumes an Air-Bag bunch distribution in a Square well.
Paper: WEPM095
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM095
About: Received: 29 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPM098
Transverse mode-coupling instability with Landau cavities at the MAX IV laboratory 1.5 GeV ring
2203
Collective effects can have a strong influence on the beam stability and performance in synchrotron light sources. Landau cavities or RF harmonic cavities are a tool that is employed at 4th generation storage ring light sources to reduce the impact of or even prevent instabilities arising from collective effects. The positive effect of Landau cavities is based on the lengthening of the electron bunches and an increase in synchrotron tune spread. Recent theoretical calculations by M. Venturini (2018) predict however, that at zero chromaticity, the threshold current of the transverse mode-coupling instability (TMCI) was reduced in the presence of Landau cavities. This contribution presents measurements conducted at the MAX IV 1.5 GeV storage ring, where, to test the prediction, the TMCI threshold was measured with and without bunch-lengthening using passive Landau cavities. The effect at non-zero chromaticity was also investigated.
Paper: WEPM098
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM098
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPM099
Investigation of the microwave instability at MAX IV laboratory in combination with intra-beam scattering
2207
With the increasingly challenging parameters in 4th generation synchrotron light sources, collective effects causing instabilities are putting even stronger limitations on the area of stable operation. The microwave instability (MWI) is a longitudinal single-bunch instability driven by the geometric and the resistive-wall impedances. While the instability typically does not result in a beam loss, the resulting turbulent dynamics are accompanied by an increased energy spread and therefore deteriorate the light source performance. The threshold current depends on different beam parameters and can, without mitigation, for recently upgraded or currently under design light sources, be as low as or lower than the intended design current per bunch. At the same time, the instability threshold is also influenced by other collective effects such as the intra-beam scattering (IBS). The influence of the IBS on the microwave instability has been studied for the 3 GeV storage ring at the MAX IV laboratory. The presented experimental results show the expected influence on the MWI threshold by the coupling strength due to the resulting changes in the IBS.
Paper: WEPM099
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM099
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPM104
Beam-based characterization of longitudinal coupled-bunch instabilities at SIRIUS storage ring
2218
SIRIUS is the 4th generation synchrotron light source of the Brazilian Synchrotron Light Laboratory (LNLS). In mid 2024 the storage ring had a major upgrade on the rf system, with the replacement of the PETRA 7-Cell rf cavity by two superconducting (SC) CESR-B cavities. It was antecipated that after the upgrade the longitudinal coupled-bunch instabilities (LCBIs), previously driven by the higher-order-modes (HOMs) of the PETRA 7-Cell cavity, would not longer occur. However, different LCBIs were observed at currents as low as 90mA. In this work, we report on the experimental methods and results to characterize these LCBIs through beam-based measurements using the bunch-by-bunch feedback system. We also present simulations to evaluate the expected impact of the harmonic cavity planned for the next operational phase.
Paper: WEPM104
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM104
About: Received: 17 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPM108
Towards operational optics measurements with AC Dipole excitations in the CERN SPS
2225
In the CERN Super Proton Synchrotron (SPS), a new AC dipole excitation functionality has been implemented with the aid of the Beam-Based Feedback and Diagnostic Systems. This feature facilitates precise and systematic optics measurements, presenting a robust alternative to the conventional single-kick excitation method. Comparative studies of AC dipole and single-kick excitations have been performed, employing linear and nonlinear optics measurements. Experimental results highlight the reliability and accuracy of the AC dipole implementation, underscoring its potential for integration in standard SPS operations for routine optics measurements.
Paper: WEPM108
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM108
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPS002
Performance of the diode stack with resistors to suppress beam instability at the J-PARC RCS
2240
The main source of beam instability in the J-PARC 3-GeV RCS is the impedance of the eight installed kickers. This arises because one end of each kicker magnet is shorted while the other end is left open during beam acceleration. The shorted-end configuration provides the benefit of power savings during beam extraction from the RCS. However, it also excites beam instability. To retain the energy-saving benefit while suppressing beam instability, we developed a diode stack with resistors and inserted it at the open ends of four kickers. This configuration effectively suppresses beam instability for smaller-emittance beams, which are delivered to the MR at J-PARC.
Paper: WEPS002
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS002
About: Received: 26 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
WEPS008
Longitudinal microwave instability in the J-PARC Main Ring
2252
Longitudinal microwave instability has been observed in the J-PARC Main Ring. The longitudinal microwave instability was observed during the debunching process for the slow extraction. This led to electron cloud formation, which can cause transverse beam instability and beam losses. Longitudinal microwave instability was also observed during the latter part of the acceleration for the fast extraction operation, even though no loss or transverse instability related to the longitudinal microwave instability was observed. To investigate the source of the longitudinal microwave instability, spectral analysis was used on the waveform recorded by a high-speed oscilloscope. The spectral analysis suggests the RF cavity and its structure as a possible source of the longitudinal microwave instability. A beam longitudinal dynamics simulation with measured longitudinal impedance of the RF cavity was performed, and its result is compared with the measurement for various beam intensities. In this paper, we present the result of the simulation and measurement of the longitudinal microwave instabilities for various beam intensities.
Paper: WEPS008
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS008
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPS009
Interaction of intrabeam scattering, longitudinal wakefield, and a passive harmonic RF cavity in SOLEIL II
2256
Synchrotron light sources worldwide are transforming into next-generation facilities with ultralow transverse emittances at the diffraction limits. With these parameters, intrabeam scattering (IBS) becomes significant and can spoil the light quality by increasing emittance. A harmonic cavity can be installed to mitigate this effect by increasing the bunch length. Another way to reduce the impact of IBS is to operate with the full transverse coupling. This contribution considers the IBS effect on SOLEIL II performance with an up-to-date impedance model, passive harmonic cavity, different insertion device gap configurations (open, close), and full transverse coupling for all foreseen operation modes. The combined effect of IBS and microwave instability (MWI) on the energy spread is reported. It is demonstrated that the contribution of IBS to energy spread increase is as important as that of MWI.
Paper: WEPS009
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS009
About: Received: 24 Apr 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPS010
Photoinjector beam halo formation due to a secondary picosecond time-delayed laser pulse
2260
Beam halo formation is a significant challenge for high-intensity accelerators, as it can lead to performance degradation and radiation safety risks. This study investigates the formation and mitigation of beam halos caused by a picosecond time-delayed laser pulse, which generates a secondary electron bunch in the same RF bucket as the main bunch. The energy difference between the two bunches creates a defocusing effect, leading to the halo generation. Experimental validation of RF-Track simulations was conducted at the AWAKE Run 2c test injector (ARTI). The research outlines methods for identifying, analyzing, and mitigating laser-driven beam halo formation, contributing to more effective control of beam halos in accelerator operations.
Paper: WEPS010
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS010
About: Received: 16 May 2025 — Revised: 31 May 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPS016
Experimental investigation of longitudinal scraping of H- bunches via photo-detachment
2275
Longitudinal emittance growth is a significant challenge in RF linacs, especially for poorly bunched beams. This stems from particles occupying outer synchrotron oscillation orbits in the LBET, causing unwanted bunch-bunch interactions and degraded beam quality. To address this, we proposed using temporally spaced laser pulses to selectively photo-detach electrons from the longitudinal head and tail regions of H- ion bunches. This approach aims to reduce particle density in extreme orbits, enhancing beam uniformity and limiting emittance growth. Our experiments employed Fermilab's 'LaserNotcher' system at the font end of the linac, delivering 1.6 MW peak power with sub-nanosecond precision. By neutralizing the first and last half-nanosecond of several H- bunches, we measured their propagation injection into the booster. Measurements of pulse width, average height, and temporal spacing over booster cycles were compared between the scraped and unscraped bunches. Statistical analysis evaluated the results’ significance, highlighting the feasibility of laser-based scraping for future linac designs to achieve higher beam energies with improved emittance control.
Paper: WEPS016
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS016
About: Received: 03 Jun 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPS018
Bunch length regulation in the LHC during controlled emittance blow-up
2279
Controlled longitudinal emittance blow-up is indispensable for the operation of the Large Hadron Collider (LHC) to counteract single-bunch loss of Landau damping during the acceleration ramp. The blow-up is performed by injecting RF phase noise in a narrow frequency band into the beam phase loop, with bunch-length feedback regulating the noise amplitude. In 2024, the variation of the bunch length due to imperfect regulation caused unacceptable beam-induced heating of certain accelerator components. In this contribution, we present the results of extensive simulation scans that have been used to optimize the feedback parameters. We show how this optimization, along with a reduction of the feedback delay on the controls side, has been implemented in the LHC and significantly improved the bunch length evolution during acceleration. Finally, we discuss the results of a measurement scan performed during an operational period of five weeks to fine-tune the blow-up feedback settings.
Paper: WEPS018
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS018
About: Received: 26 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
WEPS020
Preliminary study of higher-order mode based scheme for bunch length compression in SRF Electron guns
2283
Higher-Order Modes (HOMs) in superconducting radiofrequency (SRF) cavities are traditionally considered detrimental to efficient operation. They are often associated with beam instabilities and are actively damped. However, these “harmful” HOMs, if used strategically, can be transformed into a tool for providing extra control over the beam, which can introduce new opportunities that are not easily achievable by conventional SRF cavity-based systems. Particularly, we have investigated the feasibility of boosting ballistic bunch compression using HOMs in SRF gun. The proposed idea will be presented with preliminary simulation results. The 185 MHz SRF gun cavity used for the simulation study was modelled using the ACE3P software suite and further modelling of the compression scheme was performed using the GPT code.
Paper: WEPS020
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS020
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPS021
Simulation study on attosecond bunch generation using reversed chicane at Argonne Wakefield Accelerator (AWA)
2286
Capability for generating an attosecond bunch can provide interesting opportunities to wakefield accelerator research. We have been studying requirements and challenges in beam dynamics to produce an attosecond bunch using an existing beamline at Argonne Wakefield Accelerator (AWA) facility. One unavoidable limitation of this study is that conventional C-typed chicane is not available. Thus, a modified version of a chicane-like compressor, called a reversed chicane, is designed and running at the AWA facility. AWA’s injector and beamline were simulated using ASTRA and ELEGANT respectively. The study provided guidance toward the attosecond bunch generation. We present the simulation results and propose the modified design and operation conditions to generate the attosecond bunch at AWA facility.
Paper: WEPS021
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS021
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
WEPS022
Progress on experimental efforts to investigate CSR shielding effects
2290
A collaboration is underway to investigate the impact of CSR and shielding on the beam of various shapes as it passes through a chicane. Experimental efforts are being made at the Argonne Wakefield Accelerator (AWA) facility. Currently, the facility is equipped with two identical doglegs with reversing quadrupoles that allow doglegs to function as a chicane, and manually adjustable shielding gaps in dipole magnet chambers. A 6.4-ps-long flattop laser pulse is generated using alpha-BBO crystals, and linac phase is adjusted to either preserve the bunch length or slightly compress it through the chicane. While the expected beam behavior was observed during the initial experiment, the current chicane’s exceptionally large R56 (=0.45 m) rendered it sensitive to modulations from the alpha-BBO configuration. We have confirmed a new beam-based tuning procedure for BBO crystals at the AWA facility and its effect on modulations. We present the summary of experimental efforts to date and outline future plans.
Paper: WEPS022
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS022
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
WEPS028
Quadrupole pumping for bunch shortening in the Proton Synchrotron and Super Proton Synchrotron at CERN
2302
Quadrupole pumping is a longitudinal manipulation technique for bunch shortening, which works by modulating the RF voltage at twice the synchrotron frequency to excite bunch length oscillations. These controlled oscillations rotate the bunch in longitudinal phase space, with extraction set for when the bunch is shortest. Higher RF harmonics can also be used to linearise the synchrotron frequency distribution, reducing the formation of tails. Recently, quadrupole pumping has been proposed as a method for achieving ultra short bunches for proton-driven plasma wakefield accelerators such as the AWAKE experiment. In this contribution, we assess the performance of quadrupole pumping for the first time in the Proton Synchrotron (PS) and Super Proton Synchrotron (SPS) at CERN. Using simulations and beam measurements, we compare the effectiveness of this technique (without linearisation) against other bunch-shortening methods, including the unstable phase jump and the non-adiabatic voltage jump.
Paper: WEPS028
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS028
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPS029
Predicting losses in the SPS using longitudinal tomography during bunch shortening in the PS
2306
The efficient transfer of protons from the Proton Synchrotron (PS) to the Super Proton Synchrotron (SPS) is crucial for beams in the Large Hadron Collider (LHC). A particular challenge at the intensities required for the High-Luminosity LHC is the handover from a 40 MHz to a 200 MHz RF system. This requires a non-adiabatic bunch shortening in the PS triggered by a fast RF voltage jump. However, nonlinearity of the synchrotron frequency distribution causes tails to emerge during rotation, resulting in uncaptured beam in the SPS. The uncaptured particles lost at the start of acceleration in the SPS, and the additional flat bottom losses, can currently only be evaluated with the beam intensity and loss monitors. In this work, detailed studies of the bunch rotation in the PS were carried out both in simulations and in measurements. A tomography-based tool was developed to predict uncaptured losses in the SPS from bunch profile measurements in the PS during bunch shortening. This tool enables detailed monitoring of the PS-to-SPS transfer of LHC-type beams by identifying potential losses due to uncaptured beam, before injection into the SPS.
Paper: WEPS029
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS029
About: Received: 27 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPS036
First proton crabbing at the LHC via head-on beam-beam interaction
2317
The first experimental observation of a 10 $\mu$m crabbing orbit at 1~$\sigma_z$ induced by head-on collisions with a non-zero crossing angle ($\theta_c$) in a high-energy proton beam at the LHC is presented. This challenging measurement required both the design of a dedicated experiment and a careful calibration and optimization of the beam instrumentation to produce and detect such a subtle effect. By varying the crossing angle from positive to negative values the reversibility of the effect and its dependence on the crossing angle were also demonstrated. Lattice simulations were performed to corroborate the experimental results, showing excellent agreement with the measured crabbing amplitudes. This experiment highlights the potential of the existing wideband beam-position monitors to diagnose crabbing effects, which will be crucial in the HL-LHC upgrade.
Paper: WEPS036
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS036
About: Received: 19 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPS041
GPU accelerated longitudinal phase space tomography
2329
Longitudinal tomography is widely used in the CERN synchrotrons as an essential beam diagnostics tool. In recent years, more complex applications of phase space tomography, such as voltage calibration and multi-bunch tomography, have been explored. For these applications, large numbers of reconstructions are required, and computation time has a significant impact on usability. The current implementation is Python based, with the numerically intensive components written in C++. To further increase performance, a GPU-accelerated version has been developed using CuPy and CUDA. The most computationally demanding parts of the algorithm can now be run on the GPU, whilst maintaining the Python interface for maximum flexibility. Performance benchmarks showed speedups up to a factor of 35 in the scope of the entire application and even higher values when only considering the computationally intensive parts. This contribution discusses the implementation of GPU tomography as well as the additional performance improvements it enables.
Paper: WEPS041
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS041
About: Received: 15 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 10 Jul 2025
WEPS043
Achieving diverse beam modes with modelling and optimisation for the versatile SRF photoelectron gun at SEALab
2337
The SEALab facility in Berlin is home to an R\&D superconducting radio-frequency (SRF)photoinjector setup and beamline. Designed to support multiple varied applications - ranging from Energy Recovery Linac (ERL) to Ultrafast Electron Diffraction (UED) and Electron-Beam Water Treatment (EBWT) - SEALab requires flexible, high-precision tuning to support these diverse beam modes. These applications span over three orders of magnitude in bunch charge, emittance, and current, alongside sub-picosecond pulse lengths. This makes injector setup and tuning a significant challenge. With the world's first beam achieved at SEALab from a Na-K-Sb cathode in our SRF gun, a suite of beam dynamics models has been developed to support understanding of the beam behaviours in the gun, where no observations are possible, and operation of the commissioning process. This is comprised of a first-order analytical model, particle-in-cell (PIC) ASTRA simulations, and a machine-learning surrogate model trained for current commissioning operation ranges. These models are coupled with a Multi-Objective Bayesian Optimisation (MOBO) algorithm to enable rapid tuning across multiple beam modes. This combination of surrogate modelling and optimisation algorithm reduces optimisation timescales from hundreds of hours to minutes, allowing near-real-time tuning for the accelerator. This work presents the modelling framework, its validation, and its application to SEALab's many-mode optimisation challenges.
Paper: WEPS043
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS043
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
WEPS050
Electron cloud mitigation techniques for the FCC-ee
2354
The Future Circular Collider (FCC)-ee is a planned electron-positron collider under development. The future collider would be built in an about 91 km ring-shaped underground tunnel located beneath the French departments of Haute-Savoie and Ain, and the Swiss canton of Geneva. The FCC-ee may face challenges from electron cloud (e-cloud). The strongest effects are foreseen for the Z configuration, due to the highest number of bunches, which corresponds to the smallest bunch spacing, which is a key parameter for the e-cloud formation process. A high electron density in the beam pipe could limit the accelerator’s achievable performance through various mechanisms, such as transverse instabilities, transverse emittance growth, particle losses, vacuum degradation and additional heat loads on the inner surface of the vacuum chambers. In the design phase, the objective is to suppress the e-cloud effects in the FCC-ee. Therefore, effective e-cloud mitigation techniques, to avoid the e-cloud avalanche multiplication and its deleterious effects, are discussed in the paper.
Paper: WEPS050
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS050
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPS051
Filling pattern with non-uniform bunch spacing to mitigate e-cloud for the FCC-ee
2358
The Future Circular Collider (FCC) study is developing designs for higher performance particle colliders that could follow on from the Large Hadron Collider once it reaches the end of its high-luminosity phase. In particular, the FCC-ee is a proposed electron-positron collider that may face challenges from the electron cloud (e-cloud). Specifically, the Z configuration foresees the highest number of bunches. Consequently, this configuration could suffer more form the deleterious effects of the e-cloud, such as transverse instabilities, transverse emittance growth, particle losses, vacuum degradation and additional heat loads on the inner surface of the vacuum chambers. The e-cloud effects have been observed in several circular accelerators all over the world and it is much more commonly in those operated with positively charged particles. Presently, it is among the major performance limitations for high energy collider. Therefore, the study of e-cloud mitigation techniques is crucial during the accelerator's design stage to suppress the e-cloud avalanche multiplication. This paper analyses the use of non-uniform bunch spacing patterns as a potential e-cloud mitigation strategy.
Paper: WEPS051
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS051
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
WEPS052
Investigating electron cloud formation in FCC-ee nested magnet designs
2362
The Future Circular Collider is an ambitious international proposal for a next-generation particle accelerator complex, building upon the successes of CERN’s Large Hadron Collider. Specifically, the FCC-ee is a future circular lepton collider. The baseline design for the FCC-ee features four modes of operation, with beam energies ranging from 45.6 GeV to 182.5 GeV. Electron cloud (e-cloud) could be a concern for the FCC-ee due to the high number of bunches foreseen for the Z configuration, which results in small bunch spacing. The bunch spacing is a key parameter for the e-cloud formation process, as very small bunch spacing could lead to the avalanche multiplication and its deleterious effects. Moreover, electron trajectories are strongly influenced by externally applied magnetic fields, which could trap electrons and alter their survival time inside the vacuum chamber. The concept of nested magnets, which involves overlapping dipole fields with quadrupolar and/or sextupolar gradients, is under investigation. This approach aims to increase the dipole filling factor and reduce the synchrotron radiation. In this paper, the nested magnets are studied from the e-cloud point of view.
Paper: WEPS052
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS052
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPS063
Estimation of coupled-bunch instability induced by high-order modes of bell-shaped cavity in high current operation at SPring-8-II
2373
At the large synchrotron radiation facility SPring-8, the upgrade project “SPring-8-II” is underway to increase the radiation brightness by 100 times. In SPring-8-II, the beam energy will be reduced from 8 GeV to 6 GeV and the beam current will increase from 100 mA to 200 mA. The bell-shaped 509 MHz cavities will remain in place at SPring-8-II, with the number of cavities reduced from 32 to 16. Currently, the longitudinal coupled-bunch instability (CBI) is not observed. However, the CBI may occur due to high-order modes (HOMs) in some cavities because of the parameter changing at SPring-8-II. We estimated the threshold shunt impedance and Q-value for the CBI by using Ansys HFSS. Especially, TM011 mode at 900 MHz has a large impedance and the threshold impedance is 0.8 MΩ, which corresponds to QL~12,000 when R/Q=65Ω. On the other hand, we measured the actual QL-value of the cavities using single-bunch beam. The spectra and its Q-values of the HOM induced by the beam were measured. The results show that most cavities are below the threshold, but some cavities are over threshold. If the HOM causes instability, we plan to adjust two tuner plungers to shift them off the peak.
Paper: WEPS063
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS063
About: Received: 30 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPS070
Analysis of coupled-bunch instabilities in Diamond-II
2388
The low-frequency components of the impedance drive coupled-bunch instabilities in electron synchrotrons. In the Diamond-II storage ring, the geometric component of the impedance of some vacuum vessels is comparable in strength to the resistive-wall impedance. This study compares the growth rates of all coupled-bunch modes obtained through simulations and analytical calculations. Self-consistent simulations, incorporating the harmonic cavity along with short-range wakefields and higher-order cavity modes, show that the beam can be stabilised with and without multi-bunch feedback by adjusting the chromaticity.
Paper: WEPS070
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS070
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPS071
Microwave instability driven by terahertz-scale resistive-wall impedance in Diamond-II
2391
Vacuum vessels of the Diamond-II storage ring feature non-evaporable getter (NEG) coating which cause a resonator-like peak in the longitudinal impedance. This work demonstrates how different parameters of NEG can increase momentum-spread growth. It is shown that the spread of the coating-layer thickness amongst vacuum vessels results in significantly reduced momentum-spread growth. Insertion devices featuring rectangular geometry and NEG coating can cause a multi-peak structure of the longitudinal impedance which can drive additional momentum-spread growth.
Paper: WEPS071
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS071
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPS076
Thresholds of longitudinal multi-bunch instabilities in double harmonic RF systems
2398
Multi-bunch instabilities, often driven by narrowband impedance sources such as higher-order modes, present significant intensity limitations in synchrotrons. One approach to mitigate these instabilities is applying a double harmonic radio frequency (RF) system, which can increase the intensity threshold by enlarging the synchrotron frequency spread. In this study, intensity thresholds are calculated for different RF parameters using stability diagrams derived from the Lebedev equation. We analysed configurations and beam characteristics relevant to the synchrotrons at CERN, particularly focusing on the Super Proton Synchrotron (SPS). The semi-analytical results were then compared to macroparticle simulations and measurements. The findings reveal an unexpected beam stabilisation even if a non-monotonic amplitude dependency of the synchrotron frequency is present. Further, techniques for deducing the driving impedance parameters are discussed.
Paper: WEPS076
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS076
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPS088
Wakefield and HOMs preliminary characterization of the four-quadrant multi-cell RF accelerating structure for the ASTERIX project
2402
The goal of the ASTERIX project, proposed at INFN-LNF and funded by the CSN5, is the first-time demonstration of a practical, meter-long X-band RF structure for real linear accelerators made of hard copper and four quadrants. Our joining technique will be the TIG welding for the prototype. During the feasibility study, in the first year, we will proceed to the RF cavity design of two full structures (~ 1m long and ~100 cells), one with optimized geometry for single-bunch and the other one for multi-bunch operation. We will perform the RF design optimization, including thermo-mechanical analysis, of the multi-cell TW cavity and the RF mode-launcher (which will be integrated with the cavity in the most compact way possible) for both structures’ geometries. In this paper, we show the preliminary characterization of the higher-order modes (HOMs) and wake-fields, which are detrimental for the particle beam with high-quality parameters typically accelerated in such structures, in the case of single-bunch operation. The electromagnetic designs will be performed by using the 3D numerical codes Ansys-HFSS and CST-Microwave Studio.
Paper: WEPS088
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS088
About: Received: 29 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPS091
Intrabeam scattering in SRF "SKIF" storage ring
2408
SKIF (Russian acronym for Siberian Circular Photon Source) – is a new fourth generation synchrotron light source under construction in Novosibirsk, Russian Federation. One of the most important characteristics of the synchrotron radiation source SRF "SKIF", which in turn determines its brightness, is the ultra-low emittance of the electron beam, which depends on the operating regime and parameters of the storage ring: the intensity of the electron beam, the insertion devices parameters, the coupling coefficient of linear betatron oscillations, the elongation of the bunches, etc. Intrabeam scattering (IBS) is a collective effect that causes bunch volume inflation and brightness decrease for high intensity beams. Described in this work are the results of study of IBS impact on beam emittance, energy spread, Touschek lifetime and geometrical brightness for different operating regimes of the SRF “SKIF” storage ring.
Paper: WEPS091
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS091
About: Received: 29 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
WEPS092
Touschek lifetime and periodic beam loading effect in the storage ring of SRF "SKIF"
2411
The collective effects observed in storage rings with high-intensity beams are numerous and diverse. One such effect is that of periodic beam loading of accelerating RF cavities. This effect is contingent upon the impedance of the fundamental mode of the RF cavities and the mode of filling pattern. In a multitude of configurations, the periodic beam loading effect in storage rings leads to a change in the Touschek lifetime along the beam. This work is dedicated to the calculation of this effect in the storage ring of SRF "SKIF", a novel fourth-generation synchrotron radiation source currently under construction in Novosibirsk. Analytical calculations of this effect have been carried out for the main filling mode of the storage ring. It has been demonstrated that bunches in this regime can exhibit significantly disparate Touschek lifetimes. Furthermore, it has been shown that the effect is negligible when the RF acceptance is equal to the energy acceptance of the storage ring.
Paper: WEPS092
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS092
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPS102
Reconstructing wake functions using Haissinski distributions from multiple bunch charges
2419
Accurate knowledge of wake functions is crucial in accelerator physics, serving as the cornerstone for understanding intra-bunch interactions and for controlling or mitigating instabilities that limit accelerator performance. Haissinski distributions, which describe the steady-state longitudinal bunch density, are intrinsically determined by the wake function experienced by the bunch. While these distributions are typically computed from a given wake function, we investigate the inverse problem: extracting the wake function directly from measured Haissinski distributions. In this theoretical work, we introduce a novel method to reconstruct wake functions by utilizing Haissinski distributions obtained at multiple bunch charges. By combining these profiles into an overdetermined system, we address challenges posed by the inverse problem, which is sensitive to noise and discretization errors. Here, our preliminary results suggest that the use of regularization techniques may help achieve more stable reconstructions of the wake function.
Paper: WEPS102
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS102
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPS103
Impedance estimation and instability analysis for Korea-4GSR storage ring
2423
Korea-4GSR is a future light source in Korea with a circumference of 800 m, an energy of 4 GeV, and a maximum current of 400 mA. Due to the small aperture of the vacuum chamber (12H x 9V octagonal) and the large number of normal-conducting cavities and beam position monitors (BPMs), impedance-induced instabilities are expected to pose challenges at 400 mA operation. In this study, we estimated the storage ring impedance of Korea-4GSR and investigated both single-bunch and multi-bunch instabilities to determine optimal operational conditions, including the analysis of fill patterns
Paper: WEPS103
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS103
About: Received: 04 Jun 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
WEPS105
Benchmark study of transverse instability driven by the resistive wall impedance in the PF-HLS 2.5 GeV storage ring
2427
Effect of the transverse instability driven by the resistive wall impedance in the PF-HLS (Photon Factory Hybrid Light Source) 2.5GeV storage ring* are investigated and compared with three methods: an analytical method with azimuthal modes**, a Vlasov solver DELPHI*** and beam tracking code MBTRACK2****. The PF-HLS is proposed as the successor machine to the PF-2.5GeV ring and the PF Advanced Ring at KEK. Its concept is a 2.5/5.0GeV energy switchable high-brightness storage ring with a circumference of 750m. A feature of this ring is the adoption of isochronous cells over a large part of the ring, which allow electrons having a bunch length shorter than one nano-second to pass through without significant bunch lengthening. However, in return for this feature, the momentum compaction factor becomes small, which is estimated to 3.24x10-5. In this case, the coherent beam motion may be sensitive to the ring chromaticity. As the results, it's suggested that the higher-order modes of the coherent beam motion determine the stability of the beam. In the paper, the chromaticity dependence of the instability growth rate for each method is compared and reported in detail.
Paper: WEPS105
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS105
About: Received: 25 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
WEPS108
Studies of resonances limiting the high-brightness LHC beams in the SPS
2431
Space charge effects in combination with betatron resonances limit the performance of high-brightness LHC beams in the CERN Super Proton Synchrotron (SPS). Here we report on experimental studies performed with single-bunch proton beams, monitoring transverse emittance evolution and particle losses while performing tune scans across the horizontal and vertical planes. Two significant resonances were identified: a coupled resonance leading to emittance growth in the horizontal plane and a corresponding emittance decrease in the vertical plane, and another coupled resonance directly associated with particle losses. The resonances identified in these studies could explain the limitations of the beam brightness encountered with the multi-bunch LHC-type beams in the SPS, thus providing valuable insights for the optimization of the high-intensity beams performance.
Paper: WEPS108
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS108
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
WEPS110
An updated HL-LHC halo population model based on recent experimental measurements
2435
The transverse beam halo population in the Large Hadron Collider (LHC) has been found to carry a significant fraction of the total stored beam energy, potentially reaching several percent. With the anticipated increase in beam brightness for the High Luminosity LHC (HL-LHC), this poses an increasing risk to machine safety, particularly during abrupt orbit shifts or critical component failures. A comprehensive understanding and an accurate modelling of the transverse beam halo are crucial for simulations of beam losses around the ring as a consequence of such failure scenarios in the HL-LHC era. Various models, including Gaussian, double-Gaussian, and q-Gaussian distributions, have been used to describe the LHC beam halos for fitting the measured distributions. This paper provides an in-depth analysis of halo modelling based on collimator scraping measurements from the LHC operational Run 2 and Run 3, and evaluates the accuracy and representativeness of these different distribution models.
Paper: WEPS110
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS110
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THAD2
A method for measuring energy gain with variable plasma length at AWAKE
2469
The Advanced Wakefield (AWAKE) experiment is a proof-of-principle accelerator facility at CERN (Geneva, Switzerland). Proton bunches from the CERN Super Proton Synchrotron are used to drive wakefields in 10 metres of laser-ionised rubidium plasma, over which externally injected 19 MeV electrons are accelerated. Run 1 of AWAKE successfully demonstrated the self-modulation of the long proton bunch, and the acceleration of electrons to 2 GeV. Upgrades to the rubidium vapour source during Run 2 have enabled the use of a plasma density step, and variation of the plasma length through the insertion of foils along the source to dump the laser pulse. When placed suitably within the development of self-modulation, the density step is expected to preserve the wakefield amplitude, and therefore accelerating gradient, over longer distances than with uniform plasma. This work presents the first measurements of electron acceleration with a density step, studied as a function of the plasma length.
Paper: THAD2
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THAD2
About: Received: 08 Apr 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THAN1
Assessing the origin of the LHC beam halo
2473
Measurements of the transverse beam-halo population at large amplitudes in the Large Hadron Collider (LHC) provide crucial insights into the stored beam energy near the LHC collimators. These particles do not contribute significantly to the luminosity but their loss could impose limitations on accelerator performance through sudden loss spikes or even collimator damage in case of fast beam failures. A thorough understanding of the beam halo formation, along with the physical mechanisms driving its behaviour and evolution throughout the final stage of the LHC injection chain and during the acceleration cycle, is essential to define appropriate mitigation strategies to ensure reliable operation in view of High Luminosity LHC beam parameters. In this study, we explore potential origins of the transverse beam halo by examining experimentally multiple contributing factors to halo formation, including electron cloud effects, beam injection dynamics from the Super Proton Synchrotron (SPS), and the energy ramping process within the LHC.
Paper: THAN1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THAN1
About: Received: 27 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THAN2
Coherent stability and dynamic aperture with strong space charge for the FAIR SIS100 synchrotron
2477
Employing octupole magnets for Landau damping of transverse single-bunch instabilities in synchrotrons often restricts the dynamic aperture due to the excitation of betatron resonances. The situation complicates in the presence of strong direct space charge fields. A notable case is the 1-second accumulation plateau of the heavy-ion synchrotron SIS100 at the Facility of Antiproton and Ion Research (FAIR), which is designed to operate at beam intensities near the space charge limit. This study presents numerical simulations that establish the proposed stabilisation scheme, incorporating self-consistent space charge effects, beam coupling impedance and full lattice tracking. The analysis combines requirements for Landau damping of the resistive-wall instability and tolerable octupole current in relation to dynamic aperture. The results demonstrate effective control of collective effects for the most demanding beam production scheme with ${}^{238}$U${}^{28+}$ beams.
Paper: THAN2
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THAN2
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
THYN1
Deceleration of ion beams - Related challenges and opportunities
2487
The GSI facilities of CRYRING and HiTRAP are used for decelerating ion beams to low energies. This deceleration phase is preceded by the generation and acceleration of those ions. CRYRING and HiTRAP operate at the junction between accelerator science and atomic physics. The scientfic motivation, the operation principle, the state of the art and future outlooks are presented.
Paper: THYN1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THYN1
About: Received: 30 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPB001
Conceptual design of the vacuum system of cSTART
2499
The Karlsruhe Institute of Technology (KIT) operates research accelerator facilities for the development of new technologies for future compact light sources at the Institute for Beam Physics and Technology (IPBT). Within the cSTART project (**c**ompact **ST**orage ring for **A**ccelerator **R**esearch and **T**echnology), a Very Large Acceptance compact Storage Ring will be realized to combine a compact storage ring and a laser-plasma accelerator. The new design, based on 45° bending magnets, is suitable to store a wide momentum spread beam. Good vacuum conditions are essential for the successful operation of such an accelerator system. In our case, a final pressure of <1E-8 mbar is required. For cSTART, special care was taken to find a compact (43 m circumference), space- and cost-saving, yet efficient vacuum system design that fulfils this requirement. This article presents the vacuum concept that will be used at cSTART. This includes the selection of vacuum components, the design of the vacuum chamber and vacuum simulations.
Paper: THPB001
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB001
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM002
VHEE FLASH radiotherapy: cutting-edge research at CLEAR, the CERN Linear Electron Accelerator for Research
2691
With the current availability of cost-effective and compact electron LINACs operating in the 100-200 MeV energy range, there has been a growing interest in using Very High Energy Electron (VHEE) radiotherapy (RT) for cancer treatment. A particularly intriguing aspect is the Ultra High Dose Rate (UHDR) or FLASH dose regime, which focuses on damaging cancerous cells while sparing healthy tissues. VHEE beams are well-suited for FLASH RT, given their deep penetration and high beam current, making them effective for treating large, deep-seated tumors. The CLEAR (CERN Linear Electron Accelerator for Research) facility has been at the forefront of exploring VHEE and FLASH RT, conducting numerous unique experiments in collaboration with multidisciplinary user groups having experience in dosimetric, chemical, and biological studies. This paper introduces recent measurements, techniques, and methods used to observe the FLASH effect at CLEAR.
Paper: THPM002
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM002
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM039
Fast cyclotron beam probe at UC Davis Crocker Nuclear Laboratory
2770
The UC Davis Crocker Nuclear Laboratory houses a 72-inch multi-species Isochronous Cyclotron built in the 1960’s. For many years, previously unexplained beam dynamics have been indirectly observed at the cyclotron by both internal and external experimenters. Investigating these effects within the cyclotron, at the bunch level, has proven particularly challenging due to the cyclotron's harsh environment of strong magnetic fields, high radiation levels, intense RF interference, and limited space. To address these challenges, a compact segmented beam probe was developed, utilizing a scintillator array target coupled to a SiPM array positioned outside the cyclotron via fiber optic cables. This novel beam probe has enabled precise, high-speed measurements of individual beam bunches, providing data to theoretical models and deepening the understanding of beam dynamics allowing for more precise operation of the cyclotron. These advancements are driving efforts to optimize cyclotron performance for diverse applications, including isotope production, ocular melanoma therapy, and a variety of experimental research.
Paper: THPM039
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM039
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM042
Online analysis of proton and lead ion LHC schottky spectra
2773
The Schottky signals encode various beam and machine parameters, such as betatron tune, chromaticity, momentum deviation and transverse emittance. In this contribution we present the architecture and the performance of the system estimating these parameters in real-time, providing the only non-invasive measurement of chromaticity at the Large Hadron Collider. The obtained results are assessed based on chromaticity drift predictions and the measurements from the independent instruments. The remaining challenges are discussed with the outlook for further development given.
Paper: THPM042
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM042
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM043
Performance assessment of profile monitors at CERN’s LHC using systematic analysis tools
2777
In this paper, we investigate statistical and systematic tools to establish performance benchmarks for future beam profile measurement tools, using extensive data from both prototype and legacy Beam Wire Scanners and the Beam Synchrotron Radiation Telescope at the LHC. We detail direct and comparative analyses, including variability in beam size measurements, positioning accuracy, and profile shape fidelity relative to theoretical models, with particular focus on non-Gaussian tails influenced by the beam halo effect. This work establishes a foundation for systematic performance assessment applicable to both current and next-generation profile measurement tools.
Paper: THPM043
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM043
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM047
Direct diode detection tune measurement in the BESSY II booster
2789
The Direct Diode Detection (3D) method for transverse tune measurement, which was developed at CERN, has been implemented in numerous hadron machines and has recently been tested in electron machines. This method can provide orders of magnitude greater sensitivity to betatron oscillations than conventional beam position measurement approaches, which is particularly useful in fast-ramping synchrotrons such as the Booster of the BESSY~II light source. Typical systems used for tune measurement in an electron storage ring, which rely on the beam being in a relatively steady state, are not well-suited for fast-ramping machines; in order to measure the tune throughout the full acceleration ramp using conventional beam position approaches in the BESSY~II Booster, it is necessary to use large external excitation which disturbs injection into the storage ring. Here we describe tune measurement in the BESSY~II Booster using diode detectors, which allows for tune measurements during the full acceleration ramp with little to no external excitation and therefore no disturbance to user operation.
Paper: THPM047
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM047
About: Received: 02 Jun 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM059
Development of a DAQ system for a High Resolution cavity BPM for the future linear collider
2807
A cavity beam position monitor (cBPM) developed by CEA Saclay was installed at the end of the Accelerator Test Facility (ATF) linac to evaluate the combined performance of the monitor and its associated signal processing system. The setup incorporates a down-conversion architecture inspired by Royal Holloway, University of London (RHUL), and employs a digital down-conversion (DDC) algorithm to extract beam position. This configuration enables highsensitivity measurements of the transverse beam position. Preliminary results confirm successful signal acquisition and a clear position-dependent response, validating the integrated performance of the cBPM, analogue electronics, and digital processing chain. The results underscore the necessity of reliable local oscillator (LO) phase-locking to ensure precise position determination.
Paper: THPM059
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM059
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM063
Extended phase space tomography for EOSD simulation considering crystal geometry effects
2818
This theoretical study presents an advanced method for longitudinal phase space tomography in electron storage rings, focusing on reconstructing phase space densities from electro-optical spectral decoding (EOSD) measurements that incorporate crystal geometry effects. The EOSD crystal geometry significantly impacts the measurement signal due to signal integration along its length and interference from wake fields and Cherenkov diffraction radiation (ChDR). These effects add challenges to reconstructing the original phase space density from experimental data. To address these challenges, we integrate two theoretical frameworks. First, we employ the Vlasov-Fokker-Planck equation to model the turn-by-turn evolution of the charge density distribution. Second, CST simulations of the bunch profile characterize the electric field inside the crystal, enabling a tailored simulation for the EOSD system at the Karlsruhe Research Accelerator (KARA). By combining these approaches, we propose a refined tomography method that more accurately reconstructs the longitudinal phase space from sensor data, effectively capturing the interplay between bunch dynamics and the EOSD system configuration.
Paper: THPM063
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM063
About: Received: 23 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM064
Terahertz streaking detection for longitudinal bunch diagnostics at FLUTE
2822
The Karlsruhe Institute of Technology is currently exploring a compact method of longitudinal electron bunch diagnostics with femtosecond resolution that has recently been demonstrated for other parameter ranges. The experimental setup utilizes a THz-based streaking approach with resonator structures, achieving both high compactness and efficiency. In this paper, we report on the experimental observation of streaking signals with our Compact Transverse Deflecting System, which has been successfully tested using two different resonators, an Inverse Split-Ring Resonator and a Tilted-Slit-Resonator.
Paper: THPM064
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM064
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM068
Recent diagnostic upgrades at the Solaris storage ring
2826
This work summarizes the most significant diagnostic upgrades that have been implemented, as well as those currently under development, at the Solaris synchrotron facility. These include the installation, startup, and initial testing of a Bunch-by-Bunch Feedback (BBF) system that is currently being implemented at the Solaris synchrotron. Once operational, the BBF system will provide real-time corrections on a per-bunch basis, significantly enhancing beam stability. Efforts are also underway to develop a system for measuring the vertical and horizontal tunes without disturbing the electron beam. Additionally, a beam loss monitoring system is being developed and installed. Complementing these activities, numerous diagnostic scripts have been created, including those that utilize fast acquisition and turn-by-turn data from beam position monitors.
Paper: THPM068
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM068
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
THPM070
Development of a new clock phase shifter for phase measurement at the TPS
2832
The Taiwan Photon Source (TPS) is a 3 GeV synchrotron radiation facility located at NSRRC. Superconducting RF cavities have been installed in the booster and storage rings to ramp and refill electron beam energy. In order to measure the bunch phase of each bunch relative to the RF clock of the accelerator, a bunch phase detector (BPD) system was constructed to support measurement experiments. This detector uses the I/Q demodulator approach to calculate the beam phase. The system supplies a reference clock to the ADC at the RF frequency, along with a signal at three times the RF frequency, to enable calculation of the phase difference between the beam and the reference signal. The system includes a single-board computer (SBC) which is integrated with the control system to implement the remote phase adjustment function to make the operation more convenient. The BPD has been installed in the TPS and can provide measurement data. This paper describes the efforts in implementing this system.
Paper: THPM070
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM070
About: Received: 26 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
THPM071
Synchronous phase measurement and study at the Taiwan Photon Source
2835
A bunch-by-bunch synchrotron phase detector system has been implemented to investigate the synchronous phase behavior of the storage ring at the Taiwan Photon Source. This detector employs I/Q demodulation to cal-culate the beam phase on a bunch-by-bunch basis. The acquired data is integrated into the accelerator control system, visualized through a graphical user interface, and made available for further analysis. Independent component analysis (ICA) is employed to identify under-lying sources. For a trapezoid-like filling pattern, transi-ent beam loading effects are clearly observed in the flat-top region, whereas significant phase variations occur along the sloped edges of the pattern. During the beam decay period, an in-phase synchrotron phase oscillation at 7 kHz is observed, which originates from the rotation frequency of the radio-frequency transmitter. During injection, three distinct modes are identified through ICA decomposition. Among them, the amplitude of the syn-chronous oscillation mode shows a strong dependence on the injected bucket address.
Paper: THPM071
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM071
About: Received: 20 Apr 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
THPM075
The efforts on beam stability improvement in TPS
2845
This report discusses various efforts to improve beam stability at the Taiwan Photon Source. The Fast Orbit Feedback (FOFB) system is essential for maintaining beam stability in the light source. Considering the trade-off between FOFB reliability and performance, we optimize the FOFB parameters to achieve better orbit stability in the TPS. Occasional spikes in the Beam Position Monitor (BPM) readings are observed in a few BPM pick-ups and it would degrade the efficiency of the FOFB system. The probability of these spikes occurrence could be related to the different filling patterns and beam currents. A schedule for replacing these BPM buttons will be established. Additionally, the effect of various signal processing schemes on the beam is also examined.
Paper: THPM075
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM075
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM076
Progress towards longitudinal bunch profile monitor at the Argonne Wakefield Accelerator employing phase diversity electro-optic sampling
2848
Precise measurement of an electron bunch’s longitudinal profile is critical for wakefield accelerators as shaped electron bunches can improve transformer ratios in collinear wakefield acceleration. Electro-Optic sampling of terahertz (THz) radiation from the bunch is one of the most attractive approaches to provide a view into the structure of a relativistic electron bunch due to its non-destructive nature. Recent developments in spectral encoding methods have shown that Phase Diversity Electro-Optic Sampling (DEOS) can accurately retrieve profiles from both sub-picosecond bunches and those requiring long sampling time windows near the traditional resolution limits. We report the progress on DEOS measurements using coherent transition radiation (CTR), as well as simulations of retrieved THz fields from arbitrary shaped electron bunches using various crystal and probe-laser configurations.
Paper: THPM076
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM076
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM087
Possibilities for performance enhancement of a compact TDS at FLUTE
2862
A compact transverse-deflecting system (TDS) is being commissioned at the test facility FLUTE (Ferninfrarot Linac- und Test-Experiment) located at the Karlsruhe Institute of Technology (KIT). It has been proposed for diagnostics of short electron bunches. The idea of the technique is to use terahertz (THz) radiation, produced by the tilted-pulse front method using a part of the facility’s photoinjector laser, amplified by a sub-mm scale resonator for streaking of the electron bunch. Two types of resonators and their arrays have been studied: inverse split-ring and tilted slit resonator. Since the temporal resolution of this technique depends strongly on the electric field strength in the resonator gap, it would be desirable to increase this field strength. A horn-antenna-like device placed near the resonator has been proposed and simulated for this purpose. Simulations and geometrical parameter optimization have been performed using CST MICROWAVE STUDIO and will be presented in this contribution.
Paper: THPM087
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM087
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM088
Preliminary investigation on single-pixel Schottky diode based ultra-broadband THz detectors with ps-scale temporal resolution for future BCMs
2866
A Terahertz (THz) transition radiation monitor, as part of a Bunch compression monitor (BCM), is implemented for longitudinal bunch diagnostics at FELs such as ELBE, FLASH, or EuXFEL. Pulse energy measurements are typically carried out after each bunch compressor stage using coherent diffraction radiation (CDR) in the THz domain and pyroelectric detectors. For higher repetition rates in the MHz range, complex correction algorithms must be applied to correct signal pileup of the pyro-electric detector output, as well as limited signal-to-noise ratio, which can be overcome by using THz detectors with ultra-flat frequency response up to several THz. This work exhibits preliminary studies on developing an ultra-flat frequency response THz spectrometer. We present the developed single-pixel Schottky diode-based THz detector capable of single-shot measurements with a response time of 28.5 ps and IF bandwidth of $\sim$70 GHz. Further, the simulation result from the Schottky diode parameters is presented.
Paper: THPM088
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM088
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM089
Disentangling sudden beam loss events and fast beam abort system with the RFSoC-BPM at SuperKEKB
2870
In the SuperKEKB/Belle-II experiment, various new physics searches are conducted by colliding 4 GeV positrons and 7 GeV electrons. Future plans aim to significantly increase luminosity, targeting an integrated luminosity 100 times higher than current levels. However, the realization of this goal is challenged by the phenomenon of "Sudden Beam Loss" (SBL), characterized by the abrupt disappearance of the beam within tens of microseconds. As presented at IPAC'24, we developed the RFSoC-BOR (Bunch Oscillation Recorder) system, based on the AMD/Xilinx RF System on Chip (RFSoC). This system enables bunch-by-bunch beam position monitoring and detailed SBL data acquisition. Using the RFSoC-BOR, we analyzed SBL events, identified key contributing factors, and gained insight into strategies for mitigation. Our findings have advanced the understanding of SBL, bringing SuperKEKB closer to higher luminosity operation. Additionally, we are extending the functionality of the RFSoC-BOR to develop a fast beam abort system that improves accelerator component protection. This presentation will cover the role of the RFSoC-BOR in SBL analysis, key insights, and progress on the fast beam abort system.
Paper: THPM089
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM089
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
THPM090
Study of Cherenkov diffraction radiation from radiator with periodic structure in THz-region
2874
We have studied classical radiation from relativistic electrons at a facility, test accelerator as a coherent terahertz source (t-ACTS), the Research Center for Accelerator and Radioisotope Science (RARiS), Tohoku University. Cherenkov radiation is generated when a relativistic charged particle passes through a dielectric medium, while Cherenkov diffraction radiation (ChDR) is emitted when the relativistic charged particle passes near the dielectric medium. In general, the ChDR spectrum is broadband. However, when a periodic structure is used as a radiator, interference effects can monochromatize the ChDR. At t-ACTS, a proof-of-principle experiment in the THz region was conducted using a high-density polyethylene (HDPE) radiator with a periodic structure. We successfully measured ChDR from radiator with periodic structure and achieved narrowband ChDR (NbChDR) in the THz region. This paper will discuss the characteristics of NbChDR in the THz region, as observed at t-ACTS.
Paper: THPM090
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM090
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM102
High efficiency multi-objective Bayesian algorithm for APS-U nonlinear dynamics tuning
2905
The Advanced Photon Source (APS) facility has just completed an upgrade to become one of the world’s brightest storage-ring light sources. Machine learning (ML) methods have seen extensive use during commissioning. One important application was multi-objective tuning of dynamic aperture and lifetime, a complex high-dimensionality task intractable with classic optimization methods. In this work we will discuss novel Bayesian optimization (BO) algorithmic and implementation improvements that enabled this use case. Namely, pre-training and uncertainty-aware simulation priors, dynamic parameter space and acquisition function refinement, and an adaptive wall-time convergence criteria. We will also show results of optimization runs from 10 to 24 dimensions, benchmarking scaling and efficiency as compared to standard MOGA and MGGPO. Given the promising performance, work is proceeding on tighter BO integration into the control room.
Paper: THPM102
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM102
About: Received: 29 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPS013
Damping of quadrupole oscillations with bunch-by-bunch longitudinal RF feedback for FAIR
2976
To damp undesired longitudinal oscillations of bunched beams, the main synchrotron SIS100 of FAIR (Facility for Antiproton and Ion Research) will be equipped with a bunch-by-bunch longitudinal feedback (LFB) system. It will consist of new broadband kicker cavities and a dedicated low-level RF (LLRF) system. The LFB helps to stabilize the beam, to keep longitudinal emittance blow-up low and to minimize beam losses via damping dipole and quadrupole oscillations for up to 10 bunches individually. The topology of the LLRF signal processing is validated in closed loop with beam in the heavy-ion synchrotron SIS18 at GSI for future integration into SIS100. In a recent SIS18 machine development experiment with two bunches at flattop, quadrupole oscillations were excited for one bunch and then damped with a prototype setup of the LFB system using an existing magnetic alloy cavity as dedicated kicker cavity. This paper presents the test setup, the results of this experiment, and the proposed LLRF topology of the closed-loop LFB system. This validates a core part of the final SIS100 system.
Paper: THPS013
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS013
About: Received: 19 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPS015
Implementation and evaluation of bunch-by-bunch feedback systems at PLS-II for coupled-bunch instability mitigation
2980
In synchrotron light sources, coupled-bunch instabilities driven by resonant wakefields in the vacuum chamber pose significant challenges to beam stability and quality. This study presents the implementation and evaluation of a bunch-by-bunch feedback system at the Pohang Light Source-II (PLS-II). Utilizing state-of-the-art feedback technologies, including Dimtel iGp12 baseband processors and advanced BPM hybrid networks, the system was configured to address both transverse and longitudinal instabilities. Key demonstrations include real-time grow/damp measurements, fast tune tracking, and bunch cleaning to suppress unstable modes effectively. Comparative analysis with the SPring-8 feedback system highlights performance improvements and system tuning strategies tailored to PLS-II’s operational parameters. Results from horizontal and vertical plane modal amplitudes demonstrate robust damping capabilities, maintaining beam stability even at high currents and narrow insertion device gaps. These advancements contribute to enhanced operational efficiency and higher quality photon output at PLS-II.
Paper: THPS015
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS015
About: Received: 03 Jun 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPS027
Availability assurance in the future circular electron-positron collider (FCC-ee)
3018
The Future Circular Electron-Positron Collider (FCC-ee) is CERN’s leading proposal for the next generation of energy-frontier particle accelerators. At 91 km long, it is ambitious in size, complexity and technical objectives. Availability is a main challenge. This paper presents results from a Monte Carlo simulation that extrapolates reliability and maintain-ability from systems in current working accelerators to the FCC-ee. Significant integrated luminosity shortfall appears in all energy modes due to low availability and operational efficiency. The primary contributors are highlighted, exposing several compelling R&D opportunities.
Paper: THPS027
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS027
About: Received: 26 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
THPS079
First prototype measurements with an electro-optical bunch profile monitor for FCC-ee
3125
The future circular electron-positron collider (FCC-ee) is designed for highest luminosity to enhance the precision of high-energy particle physics experiments, spanning energies from the Z pole to the $\text{t}\bar{\text{t}}$ threshold. As outlined in its conceptual design report, high-precision measurements of the longitudinal bunch profile are required across multiple operation modes, which presents key challenges for beam instrumentation. As part of the feasibility study, a concept for an electro-optical (EO) bunch profile monitor has been developed to address these challenges, building on the existing EO beam diagnostic at the Karlsruhe Research Accelerator (KARA) at KIT. The first EO monitor prototype for FCC-ee features a novel crystal-holder design using prisms, enabling a single-pass setup crucial for measuring the long bunches during Z operation. This contribution presents the first measurement results of the EO monitor prototype for FCC-ee, which were obtained in the in-air test stand at the CERN Linear Electron Accelerator for Research (CLEAR).
Paper: THPS079
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS079
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPS082
Impact of beam background and jitter on LUXE interaction point
3129
LUXE is an international project that aims to study Quantum Electro-Dynamics processes that occur in the strong field regime. Using the electron beam from the European XFEL, this experiment will perform electron-laser and photon-laser collisions. Beamline simulations are required to understand what beam properties and backgrounds are expected at key locations. The beam optics was design and simulated with MAD-8 and this used to create a BDSIM simulation. To perform high precision interactions it is crucial that the transverse size and position of the electron beam can be measured. The variation of the beam position over time also has impacts on an efficient collision with the laser. This study uses simulated virtual measurement, wire scanning methods, and real measurements at the XFEL to evaluate those parameters. Finally, background from both the upstream beam line and the different dumps must be estimated to ensure that the impacts on the experiment are low enough. This paper present BDSIM simulations with high statistics necessary to evaluate the background. Critical for BDSIM studies is finding optimised ways to do cross-section biasing and final state splitting in the dumps.
Paper: THPS082
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS082
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPS083
Investigating beam-induced electron emission from thin wires in PSI proton beams
3133
The emission of electrons induced by beam interaction with thin targets is a phenomenon used to measure various properties of particle beams. The main processes of electron emission are: secondary emission, delta electron production and thermionic emission. The last one is not desired, because the intensity of thermionic electrons is not directly related to beam density profile. A common technique to suppress thermionic emission employs bias potential on the wire, which allows for recapturing of low energy electrons. This study investigates the effectiveness of the bias voltage method for high-brightness proton beams of the HIPA accelerator. Through experiments and simulations, the study aims to better understand the emission spectra, the suppression of thermionic emission, and the effects of beam fields on electron dynamics.
Paper: THPS083
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS083
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPS089
Measurements for beam size blowup in sudden beam loss events and analysis of the beam loss evolution mechanism
3144
The SuperKEKB electron-positron collider, which aims to achieve the world's highest luminosity, has suffered from "Sudden Beam Loss events (SBL)," in which several tens of percent of the beam current is lost and aborted within a few turns (20-30 µs). We have developed a new turn-by-turn beam size monitor to elucidate the cause and time evolution mechanism of the SBL events from a beam size variation point of view. The beam size monitor has two features: 1) it can measure the beam size variation over dozens of turns just before an SBL-induced beam aborts, and 2) it can measure independently in two different wavelength regions, X-ray and visible light, to ensure redundancy. In the SuperKEKB operation in 2024, we found that the vertical beam size blew up rapidly before a few turns of the abort, up to about ten times larger than the usual beam size. We also found that the size blowup started earlier than the beam position oscillation. In this presentation, we will discuss the mechanism of the beam size monitor we have developed, the analysis results of the measured beam size blowup, and finally, the possible cause and time evolution mechanism of the SBL events.
Paper: THPS089
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS089
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPS091
Beam instrumentation at the multi-turn linac passages of MESA
3148
We will present the status of the beam instrumentation at MESA. To put MESA into operation various diagnostic systems are necessary. To optimize the beam the position and phase with respect to the accelerating RF needs to be optimized to be able to recirculate the beam for multi-turn operation or ERL mode respectively. On the other hand, an absolute beam current measurement is necessary. This can be achieved with a DCCT on the linac axis. The instrumentation will be installed very close to our cryo modules and needs to fulfil the excellent vacuum requirements for superconducting RF.
Paper: THPS091
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS091
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPS093
Multichannel system for measuring the phase of acceleration and other parameters of beams in a cyclotron
3151
Diagnostics of charged particle beams is an important area in the field of accelerator technology. Non-destructive methods of beam diagnostics are becoming increasingly popular, as they allow measurements to be taken without changing the beam parameters. This is particularly valuable when studying continuous processes, the results of which can be distorted when using traditional diagnostic methods. Pickup electrodes are devices used for non-destructive diagnostics of charged particle beams. They are thin metal plates located along the axis of the beam motion. When a particle beam passes near a pickup electrode, it creates an electrical signal that is proportional to the beam current. This signal can be processed and analyzed using special equipment and software. A multichannel modular system with expandability has been developed to measure particle acceleration parameters, specifically the phase distribution during movement in the accelerator chamber, coordinates relative to the median plane and other parameters. The paper presents the results of testing the system at the DC-280 cyclotron at FLNR JINR and SSC at IThemba LABS.
Paper: THPS093
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS093
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPS094
Characterisation of the foreseen turn-by-turn beam position instrumentation for the cSTART storage ring
3154
The KIT cSTART project (compact storage ring for accelerator research and technology) aims to demonstrate injection and storage of a high intensity ultra-short bunch using the FLUTE LINAC, as well as a laser-plasma accelerator (LPA). cSTART is planned to operate with a wide range of demanding parameters, such as bunch charge, bunch length and energy spread (from the LPA), making it extremely challenging for the choice of beam diagnostics with large dynamic ranges that are capable of operating within specifications. Moreover, turn by turn measurements are necessary in the cSTART storage ring as bunch characteristics are expected to dramatically change within a single turn. In this paper, we will describe the planned beam diagnostics system of the cSTART storage ring focusing on the turn-by-turn signal processing and reporting on characterization tests which were performed.
Paper: THPS094
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS094
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPS107
Substrate material studies for PCB-based electro-optical bunch arrival-time monitors for XFELs
3181
The all-optical synchronization system used in many X-ray free-electron laser facilities (XFELs) relies on electro-optical bunch arrival-time monitors (EO-BAM) for measuring the single bunch arrival time with regards to an optical reference. An upgrade of the established EO-BAM is intended to achieve a sensitivity that enables stable operation with bunches down to charges of 1 pC, or to significantly increase the resolution in normal operation. Therefore, the pickup structure, the RF path and the electro-optical modulators are undergoing a fundamental redesign. The novel concept of the pickup structure comprises planar pickups on a printed circuit board (PCB) with integrated combination network and a bandwidth of up to 100 GHz. The theoretical jitter charge product of the preliminary concept has been estimated to be in the order of 9 fs pC and the concept was proven experimentally with a 67-GHz demonstrator at ELBE. In this contribution, we compare ceramic and glass substrates in terms of radiation hardness, sensitivity, and manufacturing capabilities. The achievable bandwidth and sensitivity are influenced by material losses and varying tolerances due to different fabrication methods.
Paper: THPS107
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS107
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPS109
Non-destructive measurements of non-relativistic ion beam bunch shapes at RAON
3189
Characterizing the longitudinal bunch profile is crucial for understanding beam dynamics and ensuring optimal accelerator performance. To address these needs, Capacitive Pick-Up type Bunch Shape Monitors (CPU-BSMs) were developed at the Institute for Rare Isotope Science (IRIS). These devices non-destructively measure the longitudinal bunch shapes of non-relativistic, nanosecond-scale ion beam bunches. Initial feasibility tests were conducted at a 30 MeV cyclotron to verify the performance of the CPU-BSMs. Subsequently, in 2024, the CPU-BSMs were employed during Nuclear Data Production System (NPDS) beam commissioning at the Rare Isotope Accelerator complex for ON-line experiments (RAON) to characterize both the longitudinal bunch shapes and the beam energy values. In this presentation, we will report the experimental results obtained using the CPU-BSMs during the NPDS beam commissioning at RAON.
Paper: THPS109
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS109
About: Received: 06 Jun 2025 — Revised: 14 Jun 2025 — Accepted: 14 Jun 2025 — Issue date: 10 Jul 2025
THPS120
Considerations for the transverse feedback system for the CERN FCC-ee collider ring
3206
The FCC-ee, a 90.7 km circumference e+ and e- collider under study at CERN, will require a transverse feedback system capable of handling risetimes as fast as four turns for the lowest order coupled-bunch modes. This can be realized by a distributed system of pick-ups and kickers in more than one location of the ring. The advantages are weighed with respect to the flexibility to respond to different choices of transverse tune working points and the possibility to operate the transverse kickers as an exciter for several measurement applications including as a depolarizer for energy calibration at Z and W energies. Options for the signal processing are outlined together with the overall specifications for the system components. The choice of frequency, a multiple of 40 MHz, is determined by requirements of the baseline 25 ns bunch spacing and the desire for a power efficient kicker system favoring stripline kickers. Performance of different variants of the system are compared in simulation and evaluated for added flexibility and complexity with respect to the placement in the ring.
Paper: THPS120
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS120
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
FRZD3
Highlights from Future Circular Collider Feasibility Study and Path to Construction
3266
The proposed Future Circular Collider (FCC) integrated programme consists of two stages: an electron–positron collider serving as a Higgs-boson, electroweak and top-quark factory,followed by a proton–proton collider operating at a collision energy around 100 TeV. In 2021, in response to the 2020 update of the European Strategy for Particle Physics, the CERN Council initiated the FCC Feasibility Study. This study covered, inter alia, physics objectives and potential, geology, civil engineering, technical infrastructure, territorial implementation, environmental aspects, R&D needs for the accelerators and detectors, socio-economic benefits, and cost. The FCC Feasibility Study was completed on 31 March 2025. We present a few key results along with accelerator R&D goals and discuss the next steps.
Paper: FRZD3
DOI: reference for this paper: 10.18429/JACoW-IPAC25-FRZD3
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025