optics
MOCN3
Searches for RF breakdown precursors using Cherenkov light in optical fibers
65
RF breakdown studies are crucial for machines relying on high-gradient, normal-conducting RF accelerating cavities. Searches for breakdown precursors in high-gradient test-stand data have been conducted* and highlight the need for a new diagnostic with improved temporal response**. Emission of Cherenkov light in optical fibers has been identified as one such diagnostic***, which occurs when charge showers due to breakdown are incident on the fiber. Optical fibers have been used previously as distributed Beam Loss Monitors. At the X-Band Laboratory for Accelerators and Beams (X-LAB), we position optical fibers adjacent to X-band cavities being conditioned for the proposed Compact Linear Collider (CLIC). We assess sensitivity of fibers to charge emitted by field emission and breakdown events. Since breakdown precursors may occur at sub-microsecond timescales**, we survey photon detectors best suited to examining fiber response and identifying precursors. We compare fiber signals to dark current captured by upstream and downstream Faraday Cups. In search of precursory phenomena, pulse-by-pulse evolution of fiber signals is examined for field-emission activity prior to breakdown.
Paper: MOCN3
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOCN3
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
MOPB037
Orbit alignment study in the collimation section at the European XFEL
135
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: 06 Jun 2025
MOPB044
Free electron laser optical axis measurement system
154
The polarization of the gamma-ray beam plays a critical role in experimental photonuclear research by probing angular momentum. For example, the multipolarities of the 80Se(g,n)79Se reaction can be assigned by measuring cross-sections relative to the plane of polarization*. Dynamic control over gamma beam polarization will open new opportunities in nuclear research, particularly by allowing relative asymmetries to be calculated without the uncertainty introduced by relative detector efficiency. A gamma-ray beam with rotational linear poarization and high polarization purity (Plin ~ .99) has been demonstrated at the High Intensity Gamma-ray Source (HIGS)**. Without active tuning by an accelerator physicist, polarization quality is degraded due to decoupling of the free-electron laser (FEL) axis and the electron beam orbit. The FOAMS is an active feedback system that is sensitive to the small centroid motions of the FEL optical axis. Measurement uncertainty characterization has been conducted. Ongoing work will utilize this feedback system to automatically sustain controllable gamma-ray polarization for nuclear physics experiments.
Paper: MOPB044
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB044
About: Received: 02 Jun 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPB053
Preliminary beta beating correction at the Canadian Light Source
162
The Canadian Light Source does not currently correct beta beating driven by its insertions devices. However, it has been known for some time that insertion device correlated vertical beam size changes can cause large reduction in flux at the VESPERS beamline. In this work we discuss our preliminary explorations to control the vertical beam size and correct beta beating.
Paper: MOPB053
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB053
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPB066
Compensation of an elliptically polarizing undulator in the HLS-II storage ring
194
The insertion devices (IDs) can severely affect the beam dynamics of a storage ring. Recently, a new elliptically polarizing undulator(EPU) is installed in the Hefei Light Source II (HLS-II) storage ring. The effects of this EPU can be modeled using the kick map method. In this paper, we present the kick map of the EPU with vertical mode and how it affects the beam dynamics. Since the HLS-II storage ring is compact, only four quadrupoles in the same straight section can be used to compensated the ID effect. The compensation result is also reported in this paper.
Paper: MOPB066
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB066
About: Received: 21 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPB072
Magnet crosstalk in highly-compact light-source storage ring
201
Electron storage rings based on multi-bend achromat (MBA) lattice can achieve very low natural emittances. Several fourth generation light sources have been built and operating, the natural emittances of which are a few 100 pm or even lower than 100 pm, providing high brightness photon beams to users. Since the lattice of MBA storage ring tends to be highly compact, the field of a magnet may be affected by the neighboring magnets. This effect turned out to be significant in the new Swiss Light Source storage ring with 7-BA lattice during its design study: the integral fields of magnets are altered by a few percent due to the magnet cross talk at locations, which is an order of magnitude larger than the field precision typically required. We present how we managed to reproduce the design magnetic fields and optics including the cross talk effects
Paper: MOPB072
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB072
About: Received: 24 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 06 Jun 2025
MOPB110
Research plans for the University of Hawai’i Accelerator and Free-Electron Laser Lab
250
The accelerator and free-electron laser (FEL) laboratory at the University of Hawai’i at Manoa (UHM), established by John Madey, has been in standby since his passing in 2016, with operations further paused during the pandemic. Recent efforts aim to recommission the facility, which includes a thermionic gun, an S-band linear accelerator reaching 45 MeV, and a Mark III undulator FEL oscillator producing tunable infrared light. Previously, 3 μm infrared light from this undulator demonstrated the capability to generate 10 keV X-ray photons via inverse Compton scattering. Current upgrades include enhancements to vacuum systems and linac controls. Future plans focus on enhancing cathode performance, developing 3D FEL simulations for superradiance studies, achieving phase coherence with interferometer optics, and using waveguides for THz generation. Recent GINGER simulations explored FEL oscillator output under varying Desynchronization conditions, demonstrating pulse train formation. The revived UHM accelerator will advance FEL science and train the next generation of researchers.
Paper: MOPB110
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB110
About: Received: 23 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM007
FCC-ee energy calibration and polarization - status and outlook
267
The Future electron-positron Circular Collider, FCC-ee, aims at high-precision particle physics experiments with beam energies from 45.6 to 182.5 GeV, corresponding to the Z-pole up to above the top-pair-threshold. These goals demand, among others, a precise knowledge of the center-of-mass energy and, hence, the beam energies. By depolarizing previously polarized pilot bunches and recording the change of polarization with a 3D polarimeter, it is aimed to determine the spin tune and thereby achieve a systematic uncertainty on the beam energy in the order of tens of keV. The latest progress of the work conducted by the FCC-ee energy calibration and polarization working group is reported here.
Paper: MOPM007
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM007
About: Received: 26 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM008
Towards a High Luminosity LHC with even higher performance
271
The High Luminosity LHC (HL-LHC) project aims to increase the integrated luminosity of CERN’s Large Hadron Collider (LHC) over its exploitation era up to the end of 2041 by an order of magnitude compared to the initial LHC design value. This requires doubling the bunch intensity along with several other important changes to the LHC configuration. Dedicated beam experiments in the LHC and its injectors have already demonstrated the feasibility of reaching many of the HL-LHC project design parameters, and simulations show that some parameters could be pushed to further increase the integrated luminosity or used as mitigation measures against potential shortcomings. This paper presents a review of the latest experimental results and the possible reach of the final HL-LHC parameters.
Paper: MOPM008
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM008
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM009
Optics tuning of the FCC-ee
275
The Future Circular Collider, FCC-ee, is a proposed next generation electron-positron collider aiming to provide large luminosities at beam energies from 45.6 up to 182.5 GeV. This collider faces a major challenge to deliver the design performance in the presence of realistic lattice errors. A commissioning strategy has been developed including dedicated optics designs, efficient beam-based alignment and optics corrections based on refined optics measurements. First specifications on main magnets, corrector circuits, and instrumentation have also been investigated. A summary of all these aspects is presented in this paper.
Paper: MOPM009
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM009
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM018
Energy sensitivity of the High Luminosity LHC optics at the end of the Beta* squeeze
311
During 2022 and 2023 LHC optics commissioning, it was observed that at low-beta* small changes in the beam-energy could generate substantial perturbations of the linear beam optics, requiring re-commissioning of local corrections in the experimental insertions. This issue may become even more significant at the very low beta* anticipated for operation in the High Luminosity LHC (HL-LHC). Furthermore, energy drifts, for example due to the terrestrial tides, have generally been ignored during LHC optics commissioning, with no regular corrections applied during the duration of a specific measurement campaign. This paper examines the anticipated sensitivity of HL-LHC optics corrections to energy errors at end of the beta* squeeze.
Paper: MOPM018
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM018
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
MOPM019
Correction of Long-Range Beam-Beam Driven Normal Sextupolar Resonance Driving Terms
315
Beam-based studies at the LHC injection energy showed that compensation of the strongly driven sextupolar resonance, Qx+2Qy, improved both the dynamic aperture and lifetime of the beam, even when far from the working point and on the far side of the 3Qy resonance. Thus, a reduction of other strong normal sextupolar resonance sources was of interest. In 2024, the first measurements of resonance driving terms with long-range beam-beam (LRBB) interactions were performed. These showed that LRBB was driving the same Qx+2Qy resonance strongly when colliding, in agreement with model predictions. A correction was found for the strongest normal sextupole resonances using the existing sextupole corrector magnets in the LHC, obeying the constraints on the chromatic coupling and the maximum magnet powering. Beam-based tests to validate the response of this correction with non-colliding beams have been performed along with the testing of the LRBB resonance correction during LHC commissioning.
Paper: MOPM019
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM019
About: Received: 23 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM020
Investigation of octupolar resonances in the LHC
319
During operation for luminosity production, the LHC runs with very strong Landau octupoles to ensure the collective stability of the beams. A disadvantage of this is that these octupoles can drive resonances which can be detrimental to beam lifetime. Recently, a special optics configuration has been utilised to reduce the impact of the main octupoles on lifetime. This design relies on correctly modelling the resonance driving term (RDT) response to changes in these magnetic circuits. This paper presents beam-based studies comparing the RDT response to simulations where large discrepancies were found. To try and understand the source of this, several approaches were taken. Various methods including individual circuit measurements, studies of other circuits, and tests at different energy were employed but it remained challenging to localise the source of the discrepancy around the ring. This paper presents an attempt to apply and extend a segment-by-segment method, that has been very effective at identifying local linear optics errors, to non-linear errors through analysis of RDTs.
Paper: MOPM020
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM020
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
MOPM028
Interplay between sextupole settings and single particle instabilities during the FCC-ee commissioning
351
The Future Circular Collider of electrons and positrons (FCC-ee) is designed to achieve high luminosity at center-of-mass energies ranging from the Z boson peak to the top quark threshold. During the commissioning phase, specialized optics are essential to accommodate the dynamic needs of machine tuning and beam stabilization. This paper investigates the role of sextupoles in the various FCC-ee commissioning optics, focusing on their influence on nonlinear beam dynamics. Using advanced simulation tools, we analyze how sextupole configurations impact key performance indicators, including the dynamic aperture, emittance evolution and lifetime. Strategies for optimizing sextupole strengths are explored. The findings provide critical insights for the design and optimization of the commissioning optics, ensuring efficient and reliable ramp-up to nominal operation. These results are instrumental in refining the FCC-ee commissioning strategy, supporting its broader objectives for particle physics research.
Paper: MOPM028
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM028
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM031
Tapering schemes for FCCee
363
The electron-positron Future Circular Collider (FCC-ee) is designed to operate at four beam energies, from 45.6 GeV to 182.5 GeV. At such energy levels, the circulating beam loses a significant fraction of its energy via synchrotron radiation. As a single RF insertion is foreseen in the ring, large closed-orbit shifts featuring a typical sawtooth pattern and optics distortions are induced. This in turn leads to a significant reduction of the dynamic aperture if no mitigation is implemented. The solution is to adapt the fields of the magnets to the local beam energy which is referred to as "tapering". For practical reasons, this field adjustment must be realized for groups of magnets to limit the number of powering circuits. An algorithm has bean established to self-consistently compute the tapering strengths of a given scheme, the RF phase required to compensate the energy loss and the required orbit corrections. Tapering scenarios, from coarse schemes to fine grained options are studied with the XSuite tracking code in terms of closed-orbit excursion and optics distortion. The results at the Z-pole (45.6 GeV) and $t\bar t$ (182.5 GeV) energies are discussed in detail.
Paper: MOPM031
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM031
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPM034
Modelling optics and beam-beam effects of SuperKEKB with Xsuite
375
SuperKEKB, located at KEK, is a second generation B-factory, providing beam to the Belle-II experiment. Optics design and simulation of SuperKEKB were previously performed using the optics code SAD, developed at KEK. In this paper, we present a new model of SuperKEKB using the tracking code Xsuite, developed at CERN. An alternative strategy for modelling the interaction region, with controllable final focus quadrupoles, has been adopted. Optics comparisons between the new Xsuite model and existing SAD model, as well as tracking simulations including beam-beam modelling are presented.
Paper: MOPM034
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM034
About: Received: 26 May 2025 — Revised: 01 Jun 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
MOPM037
FCC-ee optics tuning studies with pyAT and Xsuite
387
The FCC-ee is a future high-luminosity circular electron-positron collider aiming at achieving unprecedented luminosities with beam energies ranging from 45.6 up to 182.5 GeV. FCC-ee demands precise optics tuning to achieve its ambitious performance goals. This study investigates the tuning and correction of FCC-ee optics under simulated magnet misalignments, with a particular focus on the stringent initial alignment tolerances required in the Interaction Region (IR). Random misalignment errors were introduced, and correction algorithms were applied to recover the nominal lattice configuration using the pyAT optics framework. Post-correction dynamic aperture studies were conducted to assess the stability and resilience of the lattice under realistic operational scenarios. Benchmarking pyAT outcomes against the Xsuite framework validated the reliability and consistency of the corrections. The study offers valuable insights into alignment tolerance limits, correction methodologies, and their implications for beam dynamics, providing essential guidance for the development and operation of the FCC-ee.
Paper: MOPM037
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM037
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM038
FCC-ee Interaction point optics correction with alignment errors using local tuning knobs
391
Optics tuning and correction in the Interaction Point (IP) region of the FCC-ee is critical for achieving the target luminosity. By utilizing dedicated IP tuning knobs, lattice errors at multiple IP's are corrected to restore the design optics, enabling dynamic aperture studies on the fully corrected lattice. These studies, conducted using the pyAT optics code, assess the impact of corrections and the effectiveness of various tuning knobs in mitigating beam size growth at the IP's while maintaining beam stability. Benchmarking of pyAT results with the Xsuite framework ensures the reliability and robustness of the analysis. This approach provides valuable insights into the precision of IP optics tuning and its role in optimizing the collider's operational performance.
Paper: MOPM038
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM038
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPM039
Updated monochromatization Interaction Region optics design for FCC-ee GHC lattice
395
Determining Yukawa couplings of the Higgs boson is one of the most fundamental and outstanding measurements since its discovery. The FCC-ee, owing to its exceptionally high-integrated luminosity, offers the unique opportunity to measure the electron Yukawa coupling through s-channel Higgs production at 125 GeV centre-of-mass (CM) energy, provided that the CM energy spread can be reduced from 50 MeV to a level comparable to the Higgs bosons’ natural width of 4.1 MeV. To improve the energy resolution and reach the desired collision energy spread, the concept of a monochromatization mode has been proposed as a new operation mode at the FCC-ee, relying on the Interaction Region (IR) optics design with a nonzero dispersion function of opposite signs at the interaction point (IP). A first optics design and preliminary beam dynamics simulations have been carried out for version 22 of the FCC-ee GHC lattice type. In response to the continuously evolving FCC-ee GHC optics, this paper presents an optimized updated monochromatization IR optics design based on the Version 2023 of the FCC-ee GHC optics.
Paper: MOPM039
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM039
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 06 Jun 2025
MOPM040
Optimized physics performance evaluation of monochromatization interaction region optics for direct s-channel Higgs production at FCC-ee
399
The measurement of electron Yukawa coupling ($y_{e}$) via direct *s*-channel Higgs production at $\sim$125 GeV centre-of-mass (CM) energy is significantly facilitated at the FCC-ee, provided that the CM energy spread can be reduced to a level comparable to the natural width of the Higgs boson. This reduction is possible through the “monochromatization” concept, which involves generating opposite correlations between spatial position and energy deviation in the colliding beams. Following initial parametric studies for this collision mode, three different interaction region optics designs, each featuring nonzero horizontal, vertical, or combined dispersion at the interaction point, have been proposed based on the Version 2022 of the FCC-ee Global Hybrid Correction optics. In this paper, we benchmark the upper limits contours on $y_{e}$ with simulated CM energy spread and luminosity using Guinea-Pig, in order to assess, optimize, and compare their physics performances.
Paper: MOPM040
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM040
About: Received: 28 May 2025 — Revised: 06 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 06 Jun 2025
MOPM052
Bayesian methods and differentiable models for optics studies at the ISOLDE facility
442
The Isotope mass Separator On-Line facility (ISOLDE) delivers a wide range of low-energy radioactive ion beams to its experimental users. To meet varying demands, the facility uses different target materials, ionization methods, and cooling/bunching techniques, with beam configurations potentially changing weekly. To model particle transport through the transfer lines, it is essential to reconstruct the beam's initial transverse phase space for each setup, achieved via quadrupole scan measurements. This work explores the application of Bayesian techniques and differentiable models to reduce the time required to perform the beam setup.
Paper: MOPM052
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM052
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
MOPM071
Dual-purpose structure for light and heavy particles
479
A dual-purpose structure has been developed for the NICA collider accelerating heavy multiply charged ions and light polarized nuclei of protons and deuterons. For heavy multiply charged ions, it is necessary to solve the problem of intrabeam scattering, which requires minimal modulation of the envelope and dispersion function. For light particles, the problem of crossing transition energy arises. In the proposed structure, both problems are solved due to a specially developed structure of magnetic arcs. This magneto-optical structure can be used to accelerate both heavy ions and light polarized protons and deuterons without loss of beam quality.
Paper: MOPM071
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM071
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 06 Jun 2025
MOPM109
Beam-based alignment techniques for the FCC-ee
557
The Future electron-positron Circular Collider (FCC-ee) is a proposed lepton collider for high-energy particle physics succeeding the Large Hadron Collider (LHC). Its ambitious design goals demand excellent orbit and optics control and, therefore, set strict limits on alignment tolerances. One approach to relax the mechanical alignment tolerances is Beam-Based Alignment (BBA), where the offset between magnet and position measurement is determined and can later be used to steer the beam towards the magnetic centre using corrector magnets. One of the key challenges of the FCC-ee is developing an accurate and fast BBA strategy for quadrupoles and sextupoles. A parallel BBA technique is evaluated and compared in simulations for the baseline and an alternative lattice for FCC-ee using Xsuite and is presented in this paper.
Paper: MOPM109
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM109
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPS011
Improvement on beam-based alignment methods by reliability weighted average technique
593
Accurate determination of magnet centres seen by beams is the key to a successful commissioning of a particle accelerator storage ring. In this paper, several techniques to improve the beam-based alignment for a circular accelerator storage ring are introduced. Firstly, a formula to propagate the uncertainties from linear fitting is given. Secondly, a reliability weighted averaging technique based on uncertainties are applied to mitigate the impact of outliers. Thirdly, studies show that the accuracy and precision of quadrupole centre locations can be refined by using multiple corrector magnets in the process. Finally, to improve the efficiency when using multiple correctors, a monte-carlo technique is utilized. The resulting distributions of all BPM-to-Quad offset residuals derived from simulations are presented.
Paper: MOPS011
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS011
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
MOPS017
Further progress with alternative optics for the Diamond-II storage ring upgrade
609
We report the progress made on alternative optics namely low beta and low emittance cases for the DIAMOND-II storage ring upgrade. The results of optimizations of both linear and nonlinear optics as well as impacts of insertion devices on lifetime and dynamic aperture and injection scenarios will be reported.
Paper: MOPS017
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS017
About: Received: 23 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
MOPS023
Design of the front-end complex for a muon cooling demonstrator at CERN
629
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: 06 Jun 2025
MOPS029
High Luminosity LHC collimation system performance for different optics configurations
649
The High Luminosity Large Hadron Collider (HL-LHC) presents significant collimation challenges due to its high stored beam energy. An effective collimation system is critical for ensuring stable operation, protecting the superconducting magnets and minimizing background to the experiments. This paper examines the current baseline collimation configuration and potential changes to the collimation insertion optics to improve the performance in various areas, for both proton and heavy ion beam operation. The study encompasses on- and off-momentum beam loss simulations across various stages of the operational cycle. Collimation performance is assessed based on leakage to superconducting magnets, as well as losses on the tertiary collimators, to probe this source of induced background to the experimental detectors.
Paper: MOPS029
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS029
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
MOPS089
The Korea-4GSR storage ring lattice design
775
We present the lattice design features and performance evaluation of the Korea-4GSR storage ring. This greenfield ring has a 4 GeV beam energy, an 800 m circumference, and 28 cells. A natural emittance of 62 pm is achieved through the implementation of four longitudinal-gradient bends and six reverse bends within the hybrid multi-bend achromat unit cell. The ring includes two high-beta straights, designed to be nearly transparent to the normal straights. Sextupole and octupole magnet strengths have been optimized to suppress major detuning parameters, enabling the ring to achieve a large dynamic aperture and momentum aperture. Commissioning simulations were performed to investigate the optics correction strategy for each commissioning stage and to estimate the performance of the ring under error conditions.
Paper: MOPS089
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS089
About: Received: 23 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
MOPS126
Current status of conceptual horizontal splitter design for FFA@CEBAF energy Upgrade
793
Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) is currently investigating the feasibility of upgrading its maximum operating energy using Fixed-Field Alternating-gradient (FFA) recirculating arcs to increase the total number of recirculations of the beam through the pair of LINACs. These FFA arcs will be composed of permanent magnets, with small Panofsky-style multipole correctors. In order to control the beam parameters through these FFA arcs, horizontal splitters must be used. The geometrical and physical constraints, as well as the beam matching requirements are very restrictive, complicating the design. This work will show the current status of the most mature design, which includes matching solutions, as well as options for extraction of the beam.
Paper: MOPS126
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS126
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
MOPS143
Feasibility studies for a new transfer line to a muon cooling demonstrator at CERN
823
In the context of ongoing research for a future muon collider, one of the primary challenges is the efficient production and cooling of muons. To address this, a proposal is being explored to construct a demonstrator at CERN for testing a cooling cell. This demonstrator would include a target and focusing system, a chicane around a dump, and a cooling channel. A potential site for this facility is the end of the existing TT7 tunnel, which was used as a neutrino facility in the early 1980s and is presently used for storage of radioactive waste. This paper outlines the initial design studies for the transfer line that will deliver 14 GeV protons from the Proton Synchrotron to the target. The design aims to minimize costs while meeting all geometric and optical requirements. The possibility of operating the line up to 20 GeV is also explored.
Paper: MOPS143
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS143
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
TUPB022
Reduction of beam loss at the fast extraction section in J-PARC MR
982
At J-PARC MR, proton beams are supplied to the neutrino facility via fast extraction (FX). The beam power, which was 500 kW in 2021, reached 800 kW by June 2024, with further upgrades planned. This increase in power has led to a rise in beam loss in the FX section, necessitating countermeasures. Residual doses are high at positions where the FX beam orbit closely approaches the aperture, and the effectiveness of beam loss countermeasures is evaluated by changes in residual dose. By June 2024, residual doses were successfully reduced through adjustments to the beam optics. For further reduction of beam loss, in July 2024, the aperture was expanded at the most upstream position where the beam orbit is in close proximity to the aperture. This report discusses the achievements during subsequent FX operations and outlines plans for further improvements.
Paper: TUPB022
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB022
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
TUPB027
Improving the SPS beam extraction efficiency by implementation of a crystal septum
1001
The third-integer resonant extraction of the proton beam from the Super Proton Synchrotron (SPS) at CERN is a technique used for slow extraction of the circulating beam, providing a constant spill of protons to the North Area experiments. Currently, this method employs an electrostatic septum (ZS) to separate the extracted particles from the proton beam circulating in the ring. However, a fraction of the protons is lost on the mechanical parts of the ZS causing its activation, thus, limiting the efficiency of the process. In this work, the first considerations for solving this problem are presented with the implementation of a non-resonant slow extraction scheme that enables the extraction of the particles without the use of the ZS. The extraction efficiency and beam quality are benchmarked using the Xsuite particle tracking framework for a new configuration, which is compared with the present setup.
Paper: TUPB027
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB027
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
TUPB072
Progress of beam power upgrade in J-PARC main ring
1101
In the J-PARC main ring (MR), a project to increase the beam power with higher repetition rates and higher beam intensities is now in progress, aiming to achieve 1.3 MW in the fast extraction (FX) mode and >100 kW in the slow extraction (SX) mode. Beam power has generally been increasing as planned with progress of hardware upgrades and beam dynamics tuning; beam powers of 800 kW (FX) and 80 kW (SX) have been achieved as of December 2024. This paper reports on the recent progress of the beam power upgrade in MR.
Paper: TUPB072
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB072
About: Received: 31 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
TUPB082
Development of an optical diagnostics system for ion sources
1113
At iThemba LABS proton beams, extracted from an ion source, are pre-accelerated in an injector cyclotron and further accelerated in a K200 cyclotron and transported to various target stations used for radionuclide production. To gain a deeper understanding of the various processes occurring inside the plasma reservoir of the ion source and to support operational adjustments of the ion source, a novel optical emission diagnostics system is being developed in collaboration with the ISIS Facility of the Rutherford Appleton Laboratory. The proposed work builds on pioneering development of optical diagnostics of ion source plasmas and high-current beam-induced light emission at ISIS. The optical signals generated in the plasma and extraction region are collected and transported via an optical fibre to a diagnostics unit with multiple detectors suited for varying intensities and required temporal resolutions. Wavelengths of various emission lines are selected using bandpass filters. From this unit the signals are sent to a data acquisition system for processing. This contribution will present a preliminary design of the optical diagnostics system and the status of prototyping activities.
Paper: TUPB082
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB082
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
TUPM026
Advanced beam tuning and beam measurements techniques in the CLEAR facility
1193
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: 06 Jun 2025
TUPM031
Courant-Snyder formalism for modeling, optimizing and simulating broadband THz radiation transport
1208
In order to exploit the scientific potential of user-oriented accelerator facilities, it is necessary to provide adequate pump sources to enable pump-probe science. The EuXFEL R&D project, STERN, aims to equip X-ray users with an accelerator-based THz source matching the high repetition rate of the XFEL. The proposed THz radiation generation methods involve Cherenkov wakefield structures and diffraction radiation, aiming to produce a spectrum from 300 GHz to 30 THz. To enable experimental characterization, both broadband and narrowband pulses must be transported through a single beamline to a radiation-shielded laboratory. A major challenge has been the simulation, optimization and design of the STERN beamline. The OCELOT accelerator lattice optimizer is adapted for optical transport with mirrors substituting traditional focusing magnets. The performance is corroborated using a THz transport code that considers beam clipping and diffraction. The optimized beamline achieves efficient transport over 10 meters, maintaining over 75% source-to-end efficiency across the frequency range. This development marks a significant step forward in THz beamline design for advanced applications.
Paper: TUPM031
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM031
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
TUPM066
Universal mode of operation of the APPLE II undulators at the MAX IV 1.5 GeV ring
1284
At the MAX IV 1.5 GeV ring, two APPLE II undulators with period lengths of 84 mm (Bloch) and 95.2 mm (FinEstBeams) cover minimum photon energies of 7 eV and 4 eV, respectively. Operating below 80 eV, the polarization state is distorted significantly by the beamlines' optical elements. A combination of helical and linear inclined modes during undulator operation - the so-called universal mode - can compensate for the distortions. In this paper, we describe how we compensate for the effect of the undulators on the beam orbits and ring optics when operating in universal mode. Additionally, some of the achieved commissioning results at both beamlines will be shown.
Paper: TUPM066
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM066
About: Received: 13 May 2025 — Revised: 31 May 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
TUPM114
An extraction scheme for future CEBAF FFA based energy upgrade
1381
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: 06 Jun 2025
TUPS032
Wien filter method for the "Quasi-frozen" spin lattice
1462
To study the electric dipole moment of light nuclei, it is necessary to maintain the direction of the spin along the particle's motion along the ring. The first obvious solution to this problem is to use elements with an electric field that rotates the spin in the direction opposite to the spin rotation in a magnetic field. The most successful solution in this case is the Wien filter, which ensures spin rotation while maintaining the co-direction of the spin and momentum. In this case, the ring structure consists of arcs with bending magnets and straight sections on which Wien filters with crossed electric and magnetic fields are installed. The paper considers various versions of a magneto-optical structure that implements the "Quasi-frozen" spin method for studying the electric dipole moment of deuterons and protons. This approach can be used in developing an upgraded Nuclotron structure.
Paper: TUPS032
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS032
About: Received: 25 Apr 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
TUPS033
Quasi-frozen spin concept to search for the electric dipole moment of the proton and deuteron
1465
One of the possible proofs of CP violation beyond the Standard Model may be the discovery of permanent Electric Dipole Moments (EDM) of elementary particles. To search for the EDM of charged particles, the Frozen Spin (FS) concept was first proposed at BNL. The implementation of the latter involves the creation of a special storage ring in which the spin vector is preserved along the momentum and precesses due to the EDM only. In a magnetic storage ring initially not dedicated to measure the EDM, it is also possible to study the EDM by inserting electrostatic or E+B elements that compensate for the spin rotation in the bending magnets in a so-called Quasi-Frozen Spin (QFS) mode. Magneto-optical structures fulfilling the QFS condition can be used in application to study the proton and deuteron EDM and for axion search at the NICA accelerator complex. The main features of the implementation of the QFS concept are discussed, the method of measuring the EDM in the frequency domain, as well as the main spin dynamics properties of the lattice are covered.
Paper: TUPS033
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS033
About: Received: 07 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 06 Jun 2025
TUPS035
TURBO – Enabling fast energy switching for hadron therapy with constant magnetic fields
1469
The energy layer switching time is a limiting factor for hadron therapy, precluding fast beam delivery and reducing treatment efficacy. For rapid energy switching the beam delivery system must be achromatic with zero dispersion over a large energy range. At the University of Melbourne, the TURBO project will utilise Fixed Field Accelerator techniques to demonstrate transport of a ±42% momentum spread beam around a 30° bend, with constant magnetic fields to eliminate the energy switching bottleneck. This will be demonstrated with an electrostatic Pelletron accelerator. A fast-switching energy degrader with thin diamond films has been designed to quickly change proton beam energies in the range 0.5-3.0MeV, covering the full clinical range when scaled up. A new design technique using nonlinear magnetic fields for energy-dependent focusing has been developed to minimise delivered beam variations. A novel method has been found to produce nonlinear permanent magnet arrays without custom magnets, enabling fast prototyping and reuse of magnets. With these innovations, the TURBO project will demonstrate rapid energy switching for hadron therapy to enable improvements in patient outcomes.
Paper: TUPS035
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS035
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEYN1
Ultrafast visualization of quasi-three-dimensional electric field of relativistic electron beam
1652
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: 06 Jun 2025
WEBN1
Empowering a broad and diverse community in beam dynamics simulations with Xsuite
1667
Xsuite is a Python toolkit for modelling and simulation of particle accelerators, which has been developed at CERN together with collaborators from other institutes over the past four years. The code has reached a mature development stage and has become the workhorse for several studies and applications, allowing the gradual replacement of legacy tools like Sixtrack, COMBI, PyHEADTAIL. This contribution provides an overview of the code capabilities and illustrates examples in different areas of accelerator science, including low-energy hadron rings for medical applications, high-intensity hadron accelerators, synchrotron light sources, high-energy hadron and lepton colliders.
Paper: WEBN1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEBN1
About: Received: 26 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
WECN1
SLS 2.0 storage ring commissioning
1679
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: 06 Jun 2025
WEPB052
The impact of insertion devices on Solaris storage ring optics
1812
This study investigates the influence of insertion devices (IDs) on the optical properties of the Solaris electron storage ring through a combination of experimental measurements and simulations. The effects of various ID settings were analyzed using tune measurements and the Linear Optics from Closed Orbits (LOCO) method. These results were compared with simulations performed using the Python Accelerator Toolbox (pyAT). Furthermore, a Long Short-Term Memory (LSTM) neural network was developed and tested for forecasting corrector magnet currents associated with the IDs. Diagnostics included monitoring the electron beam in the storage ring and photons delivered to beamlines. Additionally, the performance of both slow and fast orbit correction systems in response to ID-induced perturbations was assessed. This work provides insights into ID impact on beam dynamics and highlights the potential of machine learning for predictive control in accelerator systems.
Paper: WEPB052
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB052
About: Received: 26 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM001
High Luminosity LHC optics: Machine development results
1905
As the High Luminosity LHC (HL-LHC) era approaches, precise control of the accelerator becomes increasingly critical. Machine studies are essential to address the forthcoming challenges and develop correction strategies based on experimental measurements. Although the upgraded inner triplets are not yet available, key features of the HL-LHC optics can still be investigated. This includes exploring the high Achromatic Telescopic Squeeze (ATS) factors in the neighboring arcs of the high-luminosity interaction regions, particularly under flat optics configurations. A beta blow-up is also implemented in the long straight section containing most of the beam instrumentation to improve their sensitivity at top energy. This paper presents experimental measurements, evaluates arc phase errors, and discusses the implementation of local corrections. Sextupole bumps in the arcs were employed to mitigate these errors, demonstrating their effectiveness in optimizing machine performance.
Paper: WEPM001
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM001
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
WEPM002
Effects of new SIRIUS IVUs on electron beam dynamics
1909
Recently, two SIRIUS hard X-ray beamlines, EMA and PAINEIRA, were upgraded by replacing their previous insertion devices (IDs) with SIRIUS’s first in-vacuum undulators (IVUs). These new IDs have a period of 18.5 mm and can achieve a peak magnetic field of 1.24 T at a minimum gap of 4.3 mm. This paper reports on the effects of these new light sources on the electron beam, including static and dynamic orbit distortions, impacts on optics, injection efficiency, and changes in the storage ring’s equilibrium parameters.
Paper: WEPM002
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM002
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
WEPM003
Layout optimization and comparison of a Carbon-ion gantry based on different mechanical structures
1913
Carbon ion therapy is one of the most effective radiotherapy methods for cancer treatment, offering superior dose conformality compared to conventional radiation therapies. The combination of carbon ion treatment with a gantry further enhances treatment effectiveness and safety. When designing a gantry, the magnet aperture must consider both the beam envelope and the beam position errors all along the gantry beamline. These errors may arise from magnetic field errors, imperfect magnet alignment, construction inaccuracies and mechanical design choices. A well-matched optics guarantees a low beam envelope; however, this does not always correspond to an optimization of the space occupied by the beam after introducing error sources and related corrections. Thus, a novel methodology that integrates optics and mechanical studies has been developed. By combining mechanical deformation analyses and optics correction optimization algorithms, this study provides a comprehensive solution for the HITRIplus carbon ion gantry design. A detailed analysis of the impact of two different design options for the supporting system of the SC magnets is provided.
Paper: WEPM003
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM003
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
WEPM006
Optics optimization and commissioning simulations for Elettra 2.0
1917
Optimization of dynamic aperture is a challenging aspect of low emittance storage ring lattice design. A large dynamic aperture is favourable for efficient injection and long beam lifetime. Several methods like simple scanning of sextupoles and octupoles strength and genetic optimization with different configurations have been successfully combined to enlarge the dynamic aperture of Elettra 2.0 and ensure high efficiency injection. Using the optimized machine we then study its commissioning via simulations including and discussing the various stages from injection to the first turn, to accumulation.
Paper: WEPM006
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM006
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 06 Jun 2025
WEPM008
3Qy resonance correction at LHC injection
1921
Compensation of the 3Qy resonance at injection energy in the LHC is of significant interest, given its potential to degrade the lifetime of high-intensity beams. In the absence of dedicated corrector circuits for the 3Qy compensation of each beam at low energy, an alternative approach is needed. Using skew-sextupoles in the four common experimental insertions it has been possible to develop a scheme to independently control the 3Qy resonance of the two LHC beams. Beam-based measurements and corrections of the 3Qy resonance at injection were performed, with beneficial impacts on lifetime and emittance growth observed.
Paper: WEPM008
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM008
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM010
Beam-based beam-beam benchmarking and correction
1925
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: 06 Jun 2025
WEPM012
Status of the CERN optics measurement and correction analysis tools
1929
With a change in the LHC machine optics foreseen for 2025 and the possible reduction of beta-star, optics commissioning will become even more of a challenge for the CERN Optics Measurement and Correction (OMC) team. In particular, the increased sensitivity of the optics to non-linear imperfections, requiring a plethora of accurate measurements, is expected to be a time consuming task. In preparation, continuous effort has been undertaken to develop new correction strategies and convert them into ready-to-use algorithms, allowing the automation of repetitive tasks while keeping the python-base software tools up-to-date. In this paper the status of these tools is summarized with highlights and improvements underlined. These tools are now widely used beyond the LHC in the entire CERN accelerator complex, as well as in Super-KEKB and for Future Circular Collider studies, and could be of great interest to correct and improve the optics in other machines.
Paper: WEPM012
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM012
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM013
Impact of the inner triplet polarity on the optics commissioning of the LHC in 2024 and 2025
1933
To mitigate the risk of radiation damage induced failure while operating the LHC beyond its initial integrated luminosity target, changes to the triplet polarity and crossing angles have been applied in the two main experimental interaction regions of the LHC. This allows for a more distributed radiation deposition in the insertion region magnets, which should allow their survival until they are replaced as part of the High Luminosity LHC upgrade from 2026-2030. These changes in the optics during 2024 and 2025 came with important challenges regarding machine commissioning and optics correction. In this paper, we discuss our experience of linear optics correction for the various triplet polarity configurations and review the implications for nonlinear optics corrections.
Paper: WEPM013
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM013
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
WEPM014
Impact of linear imperfections in the high luminosity LHC separation dipole magnets
1937
Magnetic field measurements have been performed after fabrication of new separation dipoles for the low beta-star insertion regions of the High Luminosity LHC project*. In this paper, the effect of the linear imperfections of these magnets on coupling, beam size and beta-beating are evaluated using MAD-X simulations. The results indicate that the impact of normal-oriented quadrupole errors are small and easily correctable, while for skew-oriented quadrupole imperfections corrections require a significant fraction of the arc skew quadrupoles strength. Subsequent simulation studies were therefore performed to devise potential mitigation strategies, the results of which are also reported here.
Paper: WEPM014
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM014
About: Received: 26 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM018
Optimizing beam-beam beta-beating for luminosity enhancement at the LHC
1949
The optimization of LHC operation is focused on achieving the highest possible integrated luminosity to maximize experimental data collection. Given the limitations of current detector systems, maintaining a constant level of integrated luminosity has become more critical than achieving a high peak luminosity. Techniques such as beta-leveling and separation levelling have already been implemented to adjust luminosity and enhance operational efficiency. This study describes how the beam-beam beta-beating effects propagating between the multiple experimental interaction points can serve as an additional mechanism to further increase the total integrated luminosity. The operational solutions and impact on performance will be shown for both the current LHC and its future High Luminosity upgrade.
Paper: WEPM018
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM018
About: Received: 23 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
WEPM020
Towards Improving luminosity using optics tuning and data-driven methods
1957
The results of Run 24 experiments at Relativistic Heavy Ion Collider (RHIC) for improving luminosity using optics tuning are presented in this study. In the first experiment, MADx matching was used to output magnet strengths corresponding to specific s star movements around Interaction Region 8 (IR8). The corresponding Zero Degree Calorimeter (ZDC) signal was measured in place of luminosity, and Bayesian Optimization aids search of optimal movements. It was found that values retrieved from matching were inaccurate, resulting in negative feedback loops. The second experiment focused on calculating accurate s star movements. The matching method was replaced with a linear sensitivity matrix, directly relating optics to power supply, and its null space was used to fit constraints such as hysteresis effects. At the experiment, beam losses were observed at collimators around boundary of IR8, which were fixed for the third experiment. Dynamic mode decomposition was also introduced to improve quality of turn-by-turn (TBT) data as well as accuracy and consistency of optics measurements at IR8. These improvements will be tested in the experiment of next RHIC run for luminosity optimization.
Paper: WEPM020
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM020
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
WEPM028
Beam instability suppression during debunching process through slippage factor tuning in the J-PARC Main Ring
1973
The J-PARC Main Ring achieves a high extraction efficiency of 99.5% during 30 GeV slow extraction at the current beam power of 80 kW. However, at beam powers above 30 kW, we observed ring-wide beam losses due to transverse beam instability associated with vacuum pressure rises and electron cloud effects, which are believed to be triggered by longitudinal microwave structures. To achieve stable operation at 80 kW, we implemented phase offset injection into RF buckets and two-step RF voltage reduction during debunching. For planned higher-power operations, we propose tuning the slippage factor to suppress the microwave structures during debunching. The Main Ring features a unique imaginary transition gamma lattice, and we discovered that the slippage factor can be adjusted using appropriate combinations of four quadrupole families in the arc sections while maintaining the operating tune and achromatic conditions in the long straight sections. Such slippage manipulation would be impossible in a ring with a conventional FODO lattice. The slippage factor can be ramped from its nominal value to a suppressing value during acceleration.
Paper: WEPM028
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM028
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
WEPM031
Simulation-based optimization of the injection of ultrashort non-Gaussian electron beams into a storage ring
1985
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: 06 Jun 2025
WEPM034
Beam optics model and characterization for CERN's low-energy ISOLDE transfer lines
1997
The PUMA (antiProton Unstable Matter Annihilation) experiment at CERN aims to explore the interaction of antimatter with exotic isotopes, utilizing the unique capabilities of CERN’s ISOLDE facility and Antiproton Decelerator. This contribution presents recent advancements in the beam transfer lines optics studies relevant to the success of the experiment, and to ISOLDE’s operation in general. A detailed beamline model has been developed using MAD-X and XSUITE, including the consideration of apertures and alignment errors. Quadrupole scans and kick response measurements have been employed to build and benchmark the model. In addition, tomographic reconstruction was tested, aiming to obtain a detailed characterisation of the beam's transverse phase space. A distinctive feature of ISOLDE’s beamlines is the use of electrostatic, rather than magnetic, quadrupoles. To address this, an electrostatic quadrupole model was developed and benchmarked using CST. These promising results validate the optics model, demonstrating its potential to improve beam delivery across the Low-Energy ISOLDE facility and contributing towards the PUMA experiment's operational readiness.
Paper: WEPM034
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM034
About: Received: 26 May 2025 — Revised: 31 May 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
WEPM035
Resonance Driving Terms characterization at VEPP-2000 collider
2001
The VEPP-2000 collider is a compact machine, which uses the round-beam concept to achieve high luminosity. Its compact size (24 m in circumference) limits the free space between the magnetic elements. Only 4 BPMs are installed in the ring with large phase advance between them (~2 pi). The key to improve its luminosity is to reduce the power of resonances. The implementing of the RDT measurement technique with our limitations is discussed. The presented experimental data gives basic information on the location of the considered magnetic perturbation causing the RDT.
Paper: WEPM035
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM035
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM038
Alignment tolerance studies for the cSTART storage ring
2008
The KIT cSTART project (compact STorage ring for Accelerator Research and Technology) aims to demonstrate the injection and storage of a high intensity ultra-short electron bunch in a large acceptance storage ring using the FLUTE linac and a laser plasma accelerator (LPA) as injectors. Amongst the unique features of the cSTART project is the wide dynamic range of machine and beam parameters to be employed, i.e. bunch charge, bunch length, beam energy, etc. The comparably low energy beam (40-90 MeV) will be injected on-axis and will be stored for about 100 ms without reaching equilibrium due to the absence of significant radiation damping. In order to ensure stable operation of the storage ring, we need to specify tolerable magnetic lattice misalignments and understand the impact on the beam dynamics to be able to implement adequate correction schemes. In this paper, we report on first studies and simulation results on the effects of magnet misalignment, roll angles, and field errors on the dynamic aperture and momentum acceptance of the cSTART storage ring and propose a suitable correction strategy.
Paper: WEPM038
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM038
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM054
Beam loss simulations for space charge mitigation in J-PARC MR
2054
The main ring synchrotron (MR) of the Japan Proton Accelerator Research Complex (J-PARC) provides high power proton beams to neutrino and hadron experiments. Since we are planning to increase the beam intensity from current $2.3 \times 10^{14}~$protons per pulse (ppp) to $3.3 \times 10^{14}~$ppp, we need to reduce the beam loss. In the J-PARC MR, the space charge is one of the main causes of beam loss. As a first step, we developed a new beam optics suppressing the space-charge-induced resonance which is the primary cause of the beam loss. In this paper, we report details of the beam loss mechanism in J-PARC MR by comparing the tune scan results of the present and new beam optics.
Paper: WEPM054
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM054
About: Received: 31 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
WEPM079
Analysis of resonance lines and working points of the HALF storage ring lattice
2113
The Hefei Advanced Light Facility (HALF) storage ring employs a hybrid six-bend achromat lattice with long and short straight sections. In this paper, main resonance lines of on- and off-momentum dynamic apertures (DAs) of the HALF lattice are analyzed by using frequency map analysis and considering $\beta$-beat. The combined effect of a fifth-order structural resonance and a half-integer non-structural resonance can induce notable particle loss in off-momentum DAs over a certain range of negative energy deviations. However, it has a limited impact on local momentum aperture even with relatively large $\beta$-beat. Using the analysis of resonance driving term fluctuations, the HALF lattice with a new working point is studied, which exhibits a significantly improved 6D DA in the direction of beam injection.
Paper: WEPM079
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM079
About: Received: 04 Apr 2025 — Revised: 29 May 2025 — Accepted: 30 May 2025 — Issue date: 06 Jun 2025
WEPM100
Parametric optics for FUDU lattices with strongly focusing undulators
2172
In low-energy FEL beamlines, like SXFEL-SBP at the Shanghai Synchrotron Radiation Facility and FLASH1 and FLASH2 at DESY, SASE undulators with perfectly reasonable strength may dynamically affect the optics of the Focusing-Undulator-Defocusing-Undulator (FUDU) cells, pre-matched for a given fixed set of undulator parameters, so violently that a dynamical re-adjustment of the FUDU quadrupoles becomes mandatory. Here we refine and generalize a result reported at the FEL conference 2024. Our almost-analytical result allows implementation in the control system, and is valid for fairly general symplectic coupling-free perturbing matrices. In an approximative sense it includes undulators changing along the beamline and even missing undulators in given cells.
Paper: WEPM100
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM100
About: Received: 28 May 2025 — Revised: 29 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
WEPM108
Towards operational optics measurements with AC Dipole excitations in the CERN SPS
2186
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: 06 Jun 2025
WEPM111
Experimental validation of parallel quadrupole beam-based alignment at KARA
2190
The Karlsruhe Research Accelerator (KARA), a synchrotron light source and test facility, at the Karlsruhe Institute of Technology (KIT), offers excellent conditions for testing different Beam-Based Alignment (BBA) approaches. Classical BBA approaches estimate the offset between the magnet and the closest BPM for one magnet at a time, and the required time for the BBA scales linearly with the number of magnets. Therefore, this approach is unsuitable for large storage rings like the Future electron-positron Circular Collider (FCC-ee). The time required is reduced using parallel BBA, where the magnet offset for several magnets is determined simultaneously. In this contribution, we compare new methods of parallel and individual BBA for quadrupoles at KARA. The measurement results are complemented with simulations using Xsuite and optics measurements.
Paper: WEPM111
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM111
About: Received: 09 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPM112
Characterization of beam optics considering fringe fields of quadrupole magnets in a LIPAc 5 MeV beamline
2194
The 5 MeV beamline of Phase B+ which is an intermediate commissioning stage of the Linear IFMIF Prototype Accelerator (LIPAc) consists of an MEBT, an MEBT Extension Line (MEL) where the SRF will be installed, a HEBT, and a beam dump. It has 17 quadrupole magnets, and some quads have small aperture-to-length ratios and are also densely installed in the MEBT and HEBT sections. In the early stages of Phase B+, we optimized the beam optics with the conventional hard-edge model for all the quads. However, we observed unwanted particle losses and discrepancies in the rms beam sizes between measurements and simulations due to significant fringe fields and magnetic interference. After considering the field maps and the magnetic interference of the quads in the beam optics, we could obtain the matching beam and reduce the particle losses. In this paper, we characterize the beam optics by comparing the transfer matrices with and without the fringe fields and the interferences using a conventional hard-edge model and a more accurate hard-edge model equivalent to the field maps.
Paper: WEPM112
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM112
About: Received: 16 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 06 Jun 2025
WEPM114
Orbit error correction schemes for the Helium Light Ion Compact Synchrotron HeLICS
2197
The Helium Light Ion Compact Synchrotron (HeLICS) is an innovative synchrotron design for cancer treatment currently under development in the context of the Next Ion Medical Machine Study (NIMMS) at CERN. As part of the lattice design, the beam size around the HeLICS circumference is evaluated and the optics functions optimized in order to meet the aperture requirements imposed by the magnet design. Furthermore, the impact of orbit errors arising from magnet misalignments is addressed, taking into account the required margins and tolerances. Correction strategies are proposed to compensate these alignment errors and provide sufficient orbit correction.
Paper: WEPM114
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM114
About: Received: 22 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
WEPS045
Investigating the Impact of alternative LHC optics on accelerator backgrounds at FASER using BDSIM
2302
Alternative configurations around the ATLAS experiment are investigated aiming to reduce muon rates at forward physics experiments such as FASER and SND@LHC. The Geant4 toolkit BDSIM is used to propagate muons through a model of a section of the LHC and the TI12 tunnel, where the FASER experiment is located. We compare the muon rates in BDSIM with FASER data collected during dedicated tests in the LHC. Results show a significant worsening of the background with the non-nominal polarity configuration of the triplet quadrupoles, used in 2024. The horizontal crossing angle further increased the background, however a partial mitigation of approximately 10% was found using a set of orbit corrector magnets. Additionally, nominal triplet polarity was favorable for both vertical and horizontal crossing angles. This work served as benchmark of simulations that will be used to validate future configurations.
Paper: WEPS045
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS045
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
THPB011
Design, fabrication, and characterization of 3D-printed photonic crystals for THz filtering applications in particle accelerator
2477
The advancement of broadband terahertz (THz) sources has become increasingly important for various scientific and technological applications, including those in particle accelerators. To enable tunable and flexible THz source development, components capable of selective THz spectrum filtering are essential. In this work, we investigate the use of 3D-printed photonic crystal structures, specifically woodpile designs, for THz filtering applications. Using high-precision digital light processing (DLP) 3D printing, we successfully fabricate woodpile photonic crystals with high accuracy. The fabricated structures demonstrate effective spectral filtering capabilities within the THz range, offering promising potential for applications in advanced accelerator technology and related fields.
Paper: THPB011
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB011
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
THPB015
An evaluation of collimation settings for the High Luminosity LHC baseline
2489
In the context of the High Luminosity Large Hadron Collider (HL-LHC) project, two configurations of collimator settings are being considered. A set of relaxed settings were conceived to address potential limitations due to the impedance contribution of the collimation system with the initially foreseen settings, and to increase the primary betatron cut in case of over-populated beam tails. A significant simulation campaign has been conducted, utilising Xsuite-FLUKA coupling for the first time, to estimate the cleaning performance for each of these settings with the latest optics and layout scenarios. In addition, experiments in the current LHC have been carried out to experimentally study the cleaning performance with HL-LHC settings and to validate the simulated predictions. This paper presents and examines the results of these studies, aiming to determine which collimation settings are more suitable for implementation.
Paper: THPB015
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB015
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 06 Jun 2025
THPB029
Transient Grating Spectroscopy for accelerator applications at the European Spallation Source
2522
The European Spallation Source ESS is a multi-nation, interdisciplinary research facility based on the world’s most powerful neutron source that will operate with high standards of availability and reliability minimizing downtime periods. In order to meet these goals, critical component’s performance and aging need to be constantly monitored and assessed. Transient Grating Spectroscopy (TGS), a laser-based tecnique developed for the study of nuclear materials, has been established at ESS as an investigating tool for comparing values of thermal diffusivity before and after irradiation in particle accelerators’s materials. The implementation of this non-destructive method offers a powerful instrument for assessing the characteristics of the materials during the design phase of current and future components and, with further development in terms of resizing and deployability, also opens up the possibility for its application in the online monitoring of the machine.
Paper: THPB029
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB029
About: Received: 03 Jun 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
THPB034
A radiation-resistant distributed temperature sensor for CERN’s accelerators
2533
Optical Fibre Sensors (OFS) possess unique features, such as high sensitivity, versatility, and the ability to operate in harsh radiation environments. Distributed OFS are notable for enabling real-time monitoring over large-scale facilities, making them ideal for applications in particle accelerators. Their distributed measurement capabilities provide comprehensive monitoring while offering a cost-effective alternative to conventional pointwise technologies. As part of the Innovation work package of CERN’s Personnel Safety System Consolidation program, an experimental study was conducted to characterize the performance of a radiation-hard Distributed Temperature Sensor (DTS) to complement CERN’s safety systems, addressing cryogenic leaks and fire risks. Several fire tests were performed to assess the sensor's accuracy and temporal response under emergency-like conditions. A phenomenological model was derived from these tests to predict the system's behaviour in real-world scenarios. The obtained results are key to the first deployment and operation of a dedicated DTS demonstrator in a part of the LHC in 2025.
Paper: THPB034
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB034
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
THPB057
A novel approach to qualify the straightness of electrostatic septa for the SPS slow extraction
2576
The quality of slow extraction from the SPS (Super Proton Synchrotron) to the North Area is critically influenced by the straightness tolerance of the electrostatic septum. Past observations have identified a degradation of the anode body straightness, resulting in an increased beam loss during ex- traction. A new metrology bench including optical sensors has been developed to cope with the tolerance requirements while also allowing process automation. Two distinct mea- surement procedures are currently employed: one for the anode noses and another for the individual wire metrology. A control system was developed to automate the metrology and analysis process, allowing operator and time-independent measurements and increasing process accuracy. The find- ings from these investigations provide accurate information in case corrective machining of the anode body is required. The metrology method and the described nose scan approach will further reduce beam loss during the slow extraction pro- cess.
Paper: THPB057
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB057
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
THPB058
Status of the low-Z SPS slow extraction electrostatic septum development
2580
The impact of high-flux protons on beam loss during slow extraction from the SPS to the North Area has been discussed, and improvements have been proposed focusing on reducing activation, lifetime reduction, and anode body distortion. The conducted studies shall demonstrate the feasibility of replacing the stainless-steel tank, flanges, and anode body with low-Z materials. A reduced-length prototype was fabricated to demonstrate mechanical, electrical, and vacuum performance. The paper presents the vacuum vessel development from the reduced-length prototype to the full-length setup, including numerical analysis. Prototype qualification tests, including vacuum performance, leak-tightness, high-voltage feedthrough performance, and deformation during evacuation, will be discussed to confirm that the tank remains within predicted non-linear buckling limits.
Paper: THPB058
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB058
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 06 Jun 2025
THPB086
New analysis tools for LHC aperture measurements
2600
Aperture measurements at the Large Hadron Collider (LHC) are routine procedures conducted during the early stages of beam commissioning, prior to the injection of high-intensity beams. This is to ensure that the aperture, defining the clearance for the circulating beams, is protected by the LHC collimation system. Local aperture measurements are performed to probe the available aperture at specific locations. Such measurements are carried out by applying a local orbit bump in the area of interest. The bump amplitude is increased until the beam touches the aperture, visible through signals in the local Beam Loss Monitors. This contribution introduces a refined approach to analyse local aperture measurements by incorporating measured beam position monitor (BPM) signals to enhance the precision of the analysis. Using the Xsuite package, the orbit bump is simulated and rematched to the measured BPM signal to enhance the analysis and quantify the uncertainties with respect to the theoretical beam orbit. Using past measurement data, we compare the results obtained using the established and revised methodologies and conclude on derived measurement uncertainties.
Paper: THPB086
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB086
About: Received: 14 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
THPM039
Fast cyclotron beam probe at UC Davis Crocker Nuclear Laboratory
2720
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: 06 Jun 2025
THPM063
Extended phase space tomography for EOSD simulation considering crystal geometry effects
2768
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: 06 Jun 2025
THPM072
The online emittance monitor at Taiwan Photon Source
2789
This study summarizes the X-ray pinhole camera results from two recently constructed diagnostic beamlines. We provide updated emittance and energy spread measurements for the TPS storage ring and implement online measurements for routine operational monitoring.
Paper: THPM072
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM072
About: Received: 19 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
THPM076
Progress towards longitudinal bunch profile monitor at the Argonne Wakefield Accelerator employing phase diversity electro-optic sampling
2798
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: 06 Jun 2025
THPS008
Implementation of EPU66S control system at the Taiwan Photon Source
2906
The EPU66S, an elliptically polarized undulator with a 66 mm period, is a component of the Phase III beamline project at the Taiwan Photon Source (TPS). It was successfully installed in the TPS storage ring in January 2025. The control system for the EPU66S is developed within the EPICS framework, integrating motion controllers and EtherCAT communication. This system also includes a safety interlock mechanism, which halts motion in response to limit switches, torque limit switches, emergency stop button, and linear optical encoder feedback. To ensure smooth operational testing, all hardware and software components of the EPU66S control system were fully integrated prior to installation. This paper presents the development process of the EPU66S control system, with a focus on the optimization of its motion control test platform.
Paper: THPS008
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS008
About: Received: 27 May 2025 — Revised: 29 May 2025 — Accepted: 29 May 2025 — Issue date: 06 Jun 2025
THPS011
Operational challenges of the SuperKEKB iBump feedback system
2918
To maintain optimal beam collision conditions and luminosity performance, SuperKEKB requires a fast orbit feedback dedicated to correcting offsets at the interaction point (IP). The 'iBump' feedback system calculates IP beam offset from Beam Position Monitor (BPM) measurements before and after collision and corrects by creating closed orbit bumps in the High Energy Ring (HER). This system has demonstrated robustness at stabilising IP offsets during operation. In this paper, we discuss operational aspects of the system and ongoing challenges, with a focus on the identification of vertical offset as the correction target of the iBump system. Dedicated studies on the current dependence of this feedback target as well as historical data are analysed.
Paper: THPS011
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS011
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
THPS016
A multichannel Frequency Scanning Interferometry system for large scale metrology of accelerator components
2934
In the frame of the High-Luminosity LHC (HL-LHC) project at CERN, a series of sensor solutions based on Frequency Scanning Interferometry (FSI) has been proposed for the alignment and monitoring of accelerator components along a total length of more than 800 m. The adoption of FSI technology reduces the overall cost of alignment installations, mitigates the impact of environmental noise, and limits the space required for signal cables. A development strategy for multi-channel interferometers, covering over 500 diverse FSI sensors has been put in place. This paper deals with the development and testing of the FSI interferometer. Initially, a prototype with 16 channels was installed and qualified. Following successful qualification tests, larger-scale implementations with 32 and 64 channels were deployed, enabling comprehensive tests with the entire spectrum of FSI sensors installed on a movable component. This process prepares for the deployment of the final 256-channel interferometer for the HL-LHC. This contribution presents details of the interferometer solution, encompassing optics, electronics, and software design, along with the results and analysis of the system tests.
Paper: THPS016
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS016
About: Received: 19 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
THPS021
Application of distributed temperature sensor for fire and cryogenic leak detection in accelerator tunnels
2946
High-energy accelerators like CERN’s Large Hadron Collider (LHC) present hazards characterized by temperature variations such as cryogenic leak or fire. Considering that LHC tunnels are large, underground, and radioactive areas, alternatives to traditional systems are explored to improve hazard detection. CERN is investigating the feasibility of installing a large-scale temperature monitoring system in LHC tunnels using Distributed Temperature Sensor (DTS) technology. Based on optical fibre, such a system would be resistant to the LHC radioactive environment and could detect temperature anomalies associated with both fire and cryogenic leak events. This paper presents ongoing studies and a prototype of DTS equipment in the LHC tunnel installed and tested at the beginning of 2025. This publication evaluates the DTS as a safety enhancement tool for accelerator facilities. The potential improvements brought by installing a DTS in LHC tunnels will also be discussed.
Paper: THPS021
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS021
About: Received: 19 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025
THPS034
Motion protection framework for TPS insertion device control
2990
The Taiwan Photon Source (TPS) is an advanced synchrotron radiation light source that provides high-brightness light for scientific research and industrial applications. The insertion device (ID) plays a critical role in controlling the electron beam trajectory to enhance synchrotron radiation intensity. However, due to radiation and signal interference in the operational environment, the motion control system of the ID faces challenges, especially when optical encoder anomalies occur, which can affect performance and may, under certain circumstances, lead to hardware damage. Traditional motion protection relies on software soft limits and hardware limit switches, but these mechanisms may not provide comprehensive and effective protection in the event of optical encoder failures. To address this, this paper proposes a multi-layered motion protection system. In addition to incorporating traditional protections, it also introduces an abnormality prediction mechanism based on the difference in optical encoder and potentiometer data. This mechanism can trigger an abort signal to the motor controller when an anomaly is detected to stop the abnormal motion. This architecture significantly improves the operational reliability of the TPS ID, ensuring long-term safe and stable performance.
Paper: THPS034
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS034
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
THPS038
Study on a novel laser fast abort system for SuperKEKB
2998
To ensure stable and continuous commissioning of SuperKEKB, the machine protection system (MPS) plays a crucial role in safeguarding the accelerator's hardware from damage caused by beam loss. The response time of the MPS is a critical factor in mitigating hardware damage caused by the radiation of abnormal beams. In this study, we investigate a novel laser fast abort system for the SuperKEKB accelerator to reduce the response time of the beam abort trigger. The laser, serving as the trigger signal, is transmitted through free space. Compared to the traditional method, the transmission speed is 1.5 times faster than that in optical fiber. This faster signal transmission can shorten the abort time, enabling the realization of effective MPS. The optical design for long-distance laser beam propagation and measurement of coupled laser power have been studied. Investigation will be conducted regarding the long-term stability of the laser beam inside the accelerator tunnel.
Paper: THPS038
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS038
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
THPS078
Measuring single-pass dispersion in the LHC
3067
During the LHC Ion Run in 2023, the ALICE detector observed a high level of background that prevented efficient data taking. This background was caused by different ion species generated in the betatronic collimation region that were intercepted by the Tertiary collimator near ALICE Interaction Point. The mass-to-charge ratio of these generated ions causes them to follow a different trajectory to the main ion beam, similar to off momentum particles. Since this is a single-pass effect, the closed dispersion does not describe the trajectory of these ions. Instead, the single-pass or one-pass dispersion is the relevant quantity to measure. In this paper two methods for reconstructing the single-pass dispersion based on the closed orbit and optics data are described. The methods are validated through simulations and applied to real data from the LHC 2023 Ion Run.
Paper: THPS078
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS078
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 06 Jun 2025
THPS079
First prototype measurements with an electro-optical bunch profile monitor for FCC-ee
3071
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: 06 Jun 2025
THPS104
Development and testing of an autocorrelator for measuring the duration of picosecond pulses of near infrared radiation
3120
The paper presents a design of an autocorrelator manufactured to measure the duration of infrared picosecond pulses of radiation from the 3rd laser of the Novosibirsk Free Electron Laser facility, as well as the results of testing the autocorrelator when measuring the duration of picosecond pulses in the visible range. The results and future plans for future experiments using developed autocorrelator
Paper: THPS104
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS104
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 06 Jun 2025
THPS107
Substrate material studies for PCB-based electro-optical bunch arrival-time monitors for XFELs
3127
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: 06 Jun 2025
FRYD2
Review of linear and nonlinear optics measurements in the CERN LHC
3192
The LHC is approaching the end of its third operational run, with machine protection and performance having demanded an excellent control of the single-particle dynamics. Additionally, the requirement to rapidly commission multiple diverse sets of optics configurations within each year, and from year-to-year, placed clear demands on the measurement and correction methods employed. Tight tolerances on the linear optics have been consistently achieved, with the drive to ever-more pushed optics for the High Luminosity LHC era continuing to introduce new challenges. Routine control of linear coupling has been an operational necessity, while significant progress has also been made extending the understanding and control of the optics into the nonlinear regime. This paper presents the key methods used, the results obtained, and discusses the challenges to control of the beam-optics in the LHC.
Paper: FRYD2
DOI: reference for this paper: 10.18429/JACoW-IPAC25-FRYD2
About: Received: 28 May 2025 — Revised: 06 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 06 Jun 2025
FRZD1
Latest achievements in femtosecond synchronization of large scale facilities
3198
The laser-based synchronisation systems for the European XFEL and FLASH provide femtosecond-stable timing references for tens of clients along the accelerator and the experiment halls over many kilometres of optical fibre. Recently, benchmarking experiments revealed a point-to-point timing stability with sub-femtosecond rms timing jitter. At the same time geophysical effects like ocean waves and earthquakes do not only affect the performance of the system, but their impact can clearly be identified. To improve the temporal resolution in X-ray/optical pump-probe experiments, additional arrival time monitors for both the electrons and the optical laser pulses are currently being installed, allowing for a posteriori data sorting and eventually active feedbacks. Further, the optical reference oscillators and advanced synchronisation schemes are being developed, resulting in timing jitter on the sub-hundred attoseconds level.
Paper: FRZD1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-FRZD1
About: Received: 30 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 06 Jun 2025