THBP —  Poster Session WGs A-E   (12-Oct-23   17:30—19:30)
Paper Title Page
THBP01 ESS-Bilbao RFQ Power Coupler: Design, Simulations and Tests 433
 
  • I. Bustinduy, A. Conde, D. Fernández-Cañoto, N. Garmendia, P.J. González, G. Harper, A. Kaftoosian, J. Martin, J.L. Muñoz
    ESS Bilbao, Zamudio, Spain
  • A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  ESS-Bilbao RFQ power coupler is presented. The RFQ operates at 352.2 MHz and will accelerate the 32 mA proton beam extracted from the ion source up to 3.0MeV. The RFQ will complete the ESS-Bilbao injector, that can be used by the ARGITU neutron source or as a stand-alone facility. The machining of the RFQ is finished, and vacuum tests as well as low power RF measurements have been carried out. The presented power coupler is a first iteration of the device, designed to be of easier and faster manufacturing than what might be needed for future upgrades of the linac. The coupler does not have active cooling and no brazing has been needed to assemble it. It can operate at the RF power required by the RFQ but at lower duty cycles. The dielectric window is made of polymeric material, so it can withhold the assembly using vacuum seals and bolts. Design and manufacturing issues are reported in the paper, as well as the RF tests that have been carried out at medium power. Multipacting calculations compared to measured values during conditioning are also reported. High power tests of the coupler have also been performed in the ISIS-FETS RFQ and are also described here.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP01  
About • Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 28 October 2023
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THBP02 FFA Magnet for Pulsed High Power Proton Driver 436
 
  • J.-B. Lagrange, C.W. Jolly, D.J. Kelliher, A.P. Letchford, S. Machida, I. Rodríguez, C.T. Rogers, J.D. Speed
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • S.J. Brooks
    BNL, Upton, New York, USA
  • T.-J. Kuo
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  
  Fixed Field Alternating gradient (FFA) accelerator is considered as a proton driver for the next generation spallation neutron source (ISIS-II). To demonstrate its suitability for high intensity operation, an FFA proton prototype ring is planned at RAL, called FETS-FFA. The main magnets are a critical part of the machine, and several characteristics of these magnets require attention, such as doublet spiral structure, essential operational flexibility in terms of machine optics and control of the fringe field extent from the nonlinear optics point of view. This paper will discuss the design of the prototype magnet for FETS-FFA ring.  
poster icon Poster THBP02 [5.871 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP02  
About • Received ※ 02 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 12 October 2023 — Issued ※ 23 October 2023
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THBP03 ESS-Bilbao RFQ Static Tuning Algorithm and Simulation 440
 
  • J.L. Muñoz, I. Bustinduy, A. Conde, N. Garmendia, P.J. González, J. Martin, V. Toyos
    ESS Bilbao, Zamudio, Spain
  
  The ESS-Bilbao RFQ operates at 352.2 MHz. The machining of the four RFQ segments has finished and the assembly and tuning operations will follow shorly. The static tuning and field flatness are provided by an array of 60 plunger tuners, distributed along the 3.2 meters length of the structure. There are four tuners per segment per quadrant, except for one of the segments where the ports are used by the power couplers. A bead-pull setup will provide the measurements of the field profiles, that will be collected in a matrix built up with the contributions of individual tuners. The conventional approach of inverting the matrix to get the optimum tuners distribution is explored, as well as additional optimization method. Particularly, a genetic optimization algorithm provides a very succesful tuning of the RFQ. The solution provided by this approach will be used as the initial configuration of the tuners before the bead-pull measurements are carried out. Additionally, static and dynamic tuning of the RFQ is studied by high performance computing simulations of the RFQ. The analysis of the in-house computational electromagnetics suite used for these tasks is also discussed in this paper.  
poster icon Poster THBP03 [2.285 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP03  
About • Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 28 October 2023
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THBP04 Machine Protection System for the Proposed TATTOOS Beamline at HIPA 443
 
  • J. Snuverink, P. Bucher, R. Eichler, M. Hartmann, D.C. Kiselev, D. Reggiani, E. Zimoch
    PSI, Villigen PSI, Switzerland
  
  IMPACT (Isotope and Muon Production with Advanced Cyclotron and Target Technology) is a proposed upgrade project for the High Intensity Proton Accelerator (HIPA) at the Paul Scherrer Institute (PSI). As part of IMPACT, a new radioisotope target station, TATTOOS (Targeted Alpha Tumour Therapy and Other Oncological Solutions) is planned. The TATTOOS beamline and target will be located near the UCN (Ultra Cold Neutron source) target area, branching off from the main UCN beamline. In particular, the 590 MeV proton beamline is designed to operate at a beam intensity of 100 ¿A (60 kW), requiring a continuous splitting of the main beam by an electrostatic splitter. The philosophy of the machine protection system (MPS) for the TATTOOS beamline will not differ significantly from the one already implemented for HIPA. However, it is particularly important for TATTOOS to avoid damage to the target due to irregular beam conditions. We will show the diagnostic systems involved and how the requirements of the machine protection system can be met. Emergency scenarios and protective measures are also discussed.  
poster icon Poster THBP04 [3.228 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP04  
About • Received ※ 01 October 2023 — Revised ※ 03 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 21 October 2023
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THBP05 CERN SPS Dilution Kicker Vacuum Pressure Behaviour under Unprecedented Beam Brightness 447
 
  • F.M. Velotti, M.J. Barnes, W. Bartmann, H. Bartosik, E. Carlier, G. Favia, I. Karpov, K.S.B. Li, N. Magnin, L. Mether, V. Senaj, P. Van Trappen, C. Zannini
    CERN, Meyrin, Switzerland
  
  The Super Proton Synchrotron (SPS) is the second largest synchrotron at CERN and produces high-brightness beams for the Large Hadron Collider (LHC). Recently, the dilution kicker (MKDH) of the SPS beam dump system (SBDS) has demonstrated unanticipated behaviour under high beam brightness conditions. During the 2022 and 2023 beam commissioning, the MKDH, which is routinely pulsed at high voltage, was subjected to intensities of up to 288 bunches of 2·1011 protons per bunch and bunch lengths as low as 1.5 ns. Under these conditions, all the SPS kickers and septa exhibited a rapid vacuum pressure rise and a significant temperature increase with the MKDH playing the dominant effect in restricting the maximum line density that can be attained. This paper presents the results of the collected data, emphasizes the dependence on beam parameters, and introduces a probabilistic model to illustrate the effect of MKDH conditioning observed to forecast the pressure behaviour. Finally, potential countermeasures and outlook are discussed.  
poster icon Poster THBP05 [1.913 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP05  
About • Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 19 October 2023
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THBP06 RFQ Upgrades for IFMIF-DONES 451
 
  • M. Comunian, L. Bellan, A. Palmieri, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  
  In the framework of IFMIF-DONES (International Fusion Materials Irradiation Facility- DEMO-Oriented Neutron Early Source) ¿ a powerful neutron irradiation facility for studies and certification of materials to be used in fusion reactors is planned as part of the European roadmap to fusion electricity. A possible RFQ upgrade has been designed. In this article the beam dynamics of an RFQ able to handle CW 200 mA of Deuterium, based on experience of IFMIF RFQ, will be presented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP06  
About • Received ※ 24 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 15 October 2023
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THBP08 Simulation Studies on the Low Energy Beam Transfer (LEBT) System of the ISIS Neutron Spallation Source 454
 
  • S.A. Ahmadiannamin, D.C. Faircloth, S.R. Lawrie, A.P. Letchford, T.M. Sarmento, O.A. Tarvainen
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  The transmission efficiency and beam dynamic parameters of the low-energy beam transfer (LEBT) section of proton accelerators, serving as a neutron spallation source, have a critical impact on beam loss in subsequent sections of the linear accelerator. Due to variations and mismatches, the beam parameters at the entrance of the radio-frequency quadrupole (RFQ) change, significantly affecting the transmission efficiency of the RFQ and the matching between RFQ and drift tube linac (DTL) structures. Recognizing the importance of this concept, particle-in-cell studies were conducted to optimize the LEBT section of the ISIS accelerator. This study presents the results of simulations.  
poster icon Poster THBP08 [1.081 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP08  
About • Received ※ 01 October 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 30 October 2023
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THBP09 Pushing High Intensity and High Brightness Limits in the CERN PSB after the LIU Upgrades 458
 
  • F. Asvesta, S.C.P. Albright, H. Bartosik, C. Bracco, G.P. Di Giovanni, T. Prebibaj
    CERN, Meyrin, Switzerland
  
  After the successful completion of the LHC Injectors Upgrade (LIU) project, the CERN Proton Synchrotron Booster (PSB) has produced beams with up to two times higher brightness. However, the efforts to continuously improve the beam quality for the CERN physics experiments are ongoing. In particular, the high brightness LHC beams show non-Gaussian tails in the transverse profiles that can cause losses in the downstream machines, and even at LHC injection. As a result, alternative production schemes based on triple harmonic capture are being investigated in order to preserve brightness and reduce transverse tails at the same time. In addition, in view of a possible upgrade to the ISOLDE facility that would require approximately twice the number of protons per ring, the ultimate intensity reach of the PSB is explored. In this context, injection schemes using painting both transversely and longitudinally in order to mitigate the strong space charge effects are developed.  
poster icon Poster THBP09 [0.751 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP09  
About • Received ※ 28 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 20 October 2023
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THBP10 A Linearized Vlasov Method for the Study of Transverse e-Cloud Instabilities 462
 
  • S. Johannesson, M. Seidel
    EPFL, Lausanne, Switzerland
  • G. Iadarola
    CERN, Meyrin, Switzerland
  
  Using a Vlasov approach, electron cloud driven instabilities can be modeled to study beam stability on time scales that conventional Particle In Cell simulation methods cannot access. The Vlasov approach uses a linear description of electron cloud forces that accounts for both the betatron tune modulation along the bunch and the dipolar kicks from the electron cloud. Forces from electron clouds formed in quadrupole magnets as well as dipole magnets have been expressed in this formalism. In addition, the Vlasov approach can take into account the effect of chromaticity. To benchmark the Vlasov approach, it was compared with macroparticle simulations using the same linear description of electron cloud forces. The results showed good agreement between the Vlasov approach and macroparticle simulations for strong electron clouds, with both approaches showing a stabilizing effect from positive chromaticity. This stabilizing effect is consistent with observations from the LHC.  
poster icon Poster THBP10 [4.059 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP10  
About • Received ※ 26 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 14 October 2023
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THBP11 MKP-L Impedance Mitigation and Expectations for MKP-S in the CERN-SPS 466
 
  • C. Zannini, M.J. Barnes, M.S. Beck, M. Díaz Zumel, L. Ducimetière, G. Rumolo, D. Standen, P. Trubacova
    CERN, Meyrin, Switzerland
  
  Beam coupling impedance mitigation is key in preventing intensity limitations due to beam stability issues, heating and sparking. In this framework, a very good example is the optimization of the SPS kickers beam-coupling impedance for beam-induced heating mitigation. After the optimization of the SPS extraction kickers, the SPS injection kickers became the next bottleneck for high intensity operation. This system is composed of three MKP-S tanks and one MKP-L. To accommodate LIU beam intensities, it was necessary to mitigate the beam induced heating of the MKP-L, using a shielding concept briefly reviewed in this paper. Moreover, temperature data from the 2023 run are analyzed to qualify the accuracy of the models and assess the effectiveness of the impedance mitigation. Finally, the expected limitations from the MKP-S, expected to become the new bottleneck in terms of beam induced heating, are discussed.  
poster icon Poster THBP11 [1.655 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP11  
About • Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 24 October 2023
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THBP12 Slow vs Fast Landau Damping Threshold Measurement at the LHC and Implications for the HL-LHC 470
 
  • X. Buffat, L. Giacomel, N. Mounet
    CERN, Meyrin, Switzerland
  
  The mechanism of Loss of Landau Damping by Diffusion (L2D2) was observed in dedicated experiments at the LHC using a controlled external source of noise. Nevertheless, the predictions of stability threshold by L2D2 models are plagued by the poor knowledge of the natural noise floor affecting the LHC beams. Experimental measurements of the stability threshold on slow and fast time scales are used to better constrain the model. The improved model is then used to quantify requirements in terms of Landau damping for the HL-LHC.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP12  
About • Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 30 October 2023
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THBP13 Recent Developments with the New Tools for Collimation Simulations in Xsuite 474
 
  • F.F. Van der Veken, A. Abramov, G. Broggi, F. Cerutti, M. D’Andrea, D. Demetriadou, L.S. Esposito, G. Hugo, G. Iadarola, B. Lindström, S. Redaelli, V. Rodin, N. Triantafyllou
    CERN, Meyrin, Switzerland
  
  Simulations of single-particle tracking involving collimation systems need dedicated tools to perform the different tasks needed. These include the accurate description of particle-matter interactions when a tracked particle impacts a collimator jaw; a detailed aperture model to identify the longitudinal location of losses; and others. One such tool is the K2 code in SixTrack, which describes the scattering of high-energy protons in matter. This code has recently been ported into the Xsuite tracking code that is being developed at CERN. Another approach is to couple the tracking with existing tools, such as FLUKA or Geant4, that offer better descriptions of particle-matter interactions and can treat lepton and ion beams. This includes the generation of secondary particles and fragmentation when tracking ions. In addition to the development of coupling with Geant4, the SixTrack-FLUKA coupling has recently been translated and integrated into the Xsuite environment as well. In this paper, we present the ongoing development of these tools. A thorough testing of the new implementation was performed, using as case studies various collimation layout configurations for the LHC Run 3.  
poster icon Poster THBP13 [2.785 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP13  
About • Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 23 October 2023
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THBP14 LHC Optics Measurements from Transverse Damper for the High Intensity Frontier 479
 
  • T. Nissinen, F.S. Carlier, M. Le Garrec, E.H. Maclean, T.H.B. Persson, R. Tomás García, A. Wegscheider
    CERN, Meyrin, Switzerland
  
  Current and future accelerator projects are pushing the brightness and intensity frontier, creating new challenges for turn-by-turn based optics measurements. Transverse oscillations are limited in amplitude due to particle losses. The LHC Transverse Damper (ADT) is capable of generating low amplitude ac-dipole like transverse coherent beam oscillations. While the amplitude of such excitations is low, it is compensated by the excitation length of the ADT which, in theory, can last for up to 48h. Using the ADT, it is possible to use the maximum BPM acquisition length and improve the spectral resolution. First optics measurements have been performed using the ADT in the LHC in 2023, and the results are presented in this paper. Furthermore, some observed limitations of this method are presented and their impact on ADT studies are discussed.  
poster icon Poster THBP14 [2.632 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP14  
About • Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 25 October 2023
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THBP15 Optimizing Resonance Driving Terms Using MAD-NG Parametric Maps 483
 
  • L. Deniau, S. Kostoglou, E.H. Maclean, K. Paraschou, T.H.B. Persson, R. Tomás García
    CERN, Meyrin, Switzerland
  
  In 2023, a review of the LHC octupolar resonance driving terms at injection was carried out, motivated by two observations: (i) unwanted losses during the injection process with strongly powered octupoles and (ii) an expected reduction in emittance growth from e-cloud effects in simulations with weaker octupolar resonances. The MAD-NG code was used to simultaneously optimise the main octupolar resonances: 4Qx, 4Qy, and 2Qx-2Qy by adjusting 16 quadrupole families and 16 octupole families, for a total of 32 parameters. These knobs were introduced as parameters in the transfer map, allowing the Jacobian required by the optimiser to be calculated in a single pass, saving 32 additional optics evaluations and avoiding finite difference approximations. Constraints on tunes, amplitude detuning and optics around the machine were also considered as part of the optimisation process. This paper reviews the parametric optimisation with MAD-NG and compares the results with MADX-PTC.  
poster icon Poster THBP15 [0.938 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP15  
About • Received ※ 02 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 17 October 2023
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THBP16 Emittance Growth From Electron Clouds Forming in the LHC Arc Quadrupoles 487
 
  • K. Paraschou, H. Bartosik, L. Deniau, G. Iadarola, E.H. Maclean, L. Mether, Y. Papaphilippou, G. Rumolo, R. Tomás García
    CERN, Meyrin, Switzerland
  • T. Pieloni, J.M.B. Potdevin
    EPFL, Lausanne, Switzerland
  
  Operation of the Large Hadron Collider with proton bunches spaced 25 ns apart favours the formation of electron clouds. In fact, a slow emittance growth is observed in proton bunches at injection energy (450 GeV), showing a bunch-by-bunch signature that is compatible with electron cloud effects. The study of these effects is particularly relevant in view of the planned HL-LHC upgrade, which relies on significantly increased beam intensity and brightness. Particle tracking simulations that take into account both electron cloud effects and the non-linear magnetic fields of the lattice suggest that the electron clouds forming in the arc quadrupoles are responsible for the observed degradation. In this work, the simulation results are studied to gain insight into the mechanism which drives the slow emittance growth. Finally, it is discussed how optimising the optics of the lattice can allow the mitigation of such effects.  
poster icon Poster THBP16 [3.432 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP16  
About • Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 11 October 2023
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THBP17 Transverse Coherent Instability Studies for the High-Energy Part of the Muon Collider Complex 491
 
  • D. Amorim, F. Batsch, L. Bottura, D. Calzolari, C. Carli, H. Damerau, A. Grudiev, A. Lechner, E. Métral, D. Schulte, K. Skoufaris
    CERN, Geneva, Switzerland
  • A. Chancé
    CEA-DRF-IRFU, France
  • T. Pieloni
    EPFL, Lausanne, Switzerland
  
  Funding: This project has received funding from the European Union¿s Research and Innovation programme under GA No 101094300 and the Swiss Accelerator Research and Technology (CHART) program (www.chart.ch).
The International Muon Collider Collaboration (IMCC) is studying a 3 TeV center-of-mass muon collider ring, as well as a possible next stage at 10 TeV. Muons being 200 times heavier than electrons, limitations from synchrotron radiation are mostly suppressed, but the muon decay drives the accelerator chain design. After the muon and anti-muon bunches are produced and 6D cooled, a series of Linac, recirculating Linac and Rapid Cycling Synchrotron (RCS) quickly accelerate the bunches before the collider ring. A large number of RF cavities are required in the RCS to ensure that over 90% of the muons survive in each ring. The effects of cavities higher-order modes on transverse coherent stability have been looked at in detail, including the one of a bunch offset in the cavities, along with possible mitigation measures. In the collider ring, the decay of high-energy muons is a challenge for heat load management and radiation shielding. A tungsten liner would protect the superconducting magnet from decay products. Impedance and related beam stability have been investigated to identify the minimum vacuum chamber radius and transverse damper properties required for stable beams. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP17  
About • Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 01 November 2023
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THBP18 Revised Collimation Configuration for the Updated FCC-hh Layout 495
 
  • A. Abramov, R. Bruce, M. Giovannozzi, G. Pérez Segurana, S. Redaelli, T. Risselada
    CERN, Meyrin, Switzerland
  
  The collimation system for the hadron Future Circular Collider (FCC-hh) must handle proton beams with an unprecedented nominal beam energy and stored beam energy in excess of 8 GJ, and protect the superconducting magnets and other sensitive equipment while ensuring a high operational efficiency. The recent development of the 16-dipole lattice baseline for the FCC-hh, and the associated layout changes, has necessitated an adaptation of the collimation system. A revised configuration of the collimation system is presented, considering novel high-beta optics in the betatron collimation insertion. Performance is evaluated through loss map studies, with a focus on losses in critical areas, including collimation insertions and experimental interaction regions.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP18  
About • Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 19 October 2023
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THBP19 Experimental Investigations on the High-Intensity Effects Near the Half-Integer Resonance in the PSB 499
 
  • T. Prebibaj, F. Antoniou, F. Asvesta, H. Bartosik
    CERN, Meyrin, Switzerland
  • G. Franchetti
    GSI, Darmstadt, Germany
  
  Space charge effects are the main limitation for the brightness performance of the Proton Synchrotron Booster (PSB) at CERN. Following the upgrades of the LHC Injectors Upgrade (LIU) project, the PSB delivered unprecedented brightness even exceeding the projected target parameters. A possibility for further increasing the brightness is to operate above the half-integer resonance 2Qy=9 in order to avoid emittance blow-up from resonances at Qx,y=4 due to the strong space charge detuning. The half-integer resonance can be compensated to a great extent using the available quadrupole correctors in the PSB, and also deliberately excited in a controlled way. The control of the half-integer resonance and the flexibility of the PSB to create a variety of different beam and machine conditions allowed the experimental characterization of space charge effects near this resonance. This contribution reports the experimental observations of the particle trapping during the dynamic crossing of the half-integer, as well as systematic studies of the beam degradation from space charge induced resonance crossing.  
poster icon Poster THBP19 [3.077 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP19  
About • Received ※ 30 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 23 October 2023
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THBP20 Optics for Landau Damping with Minimized Octupolar Resonances in the LHC 503
 
  • R. Tomás García, F.S. Carlier, L. Deniau, J. Dilly, J. Keintzel, S. Kostoglou, M. Le Garrec, E.H. Maclean, K. Paraschou, T.H.B. Persson, F. Soubelet, A. Wegscheider
    CERN, Meyrin, Switzerland
  
  Operation of the Large Hadron Collider (LHC) requires strong octupolar magnetic fields to suppress coherent beam instabilities. The amplitude detuning that is generated by these octupolar magnetic fields brings the tune of individual particles close to harmful resonances, which are mostly driven by the octupolar fields themselves. In 2023, new optics were deployed in the LHC at injection with optimized betatronic phase advances to minimize the resonances from the octupolar fields without affecting the amplitude detuning. This paper reports on the optics design, commissioning and the lifetime measurements performed to validate the optics.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP20  
About • Received ※ 01 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 23 October 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THBP21 Increasing High Luminosity LHC Dynamic Aperture Using Optics Optimizations 507
 
  • R. De Maria, Y. Angelis, C.N. Droin, S. Kostoglou, F. Plassard, G. Sterbini, R. Tomás García
    CERN, Meyrin, Switzerland
  
  Funding: Work supported by the HL-LHC project.
CERN’s Large Hadron Collider (LHC) is expected to operate with unprecedented beam current and brightness from the beginning of Run 4 in 2029. In the context of the High Luminosity LHC project, the baseline operational scenarios are currently being developed. They require a large octupole current and a large chromaticity throughout the entire cycle, which drives a strong reduction of dynamic aperture, in particular at injection and during the luminosity production phase. Despite being highly constrained, the LHC optics and sextupole and octupole corrector circuits still offer a few degrees of freedom that can be used to reduce resonances and the extent of the tune footprint at constant Landau damping, thereby leading to an improvement of the dynamic aperture. This contribution presents the status of the analysis that will be used to prepare the optics baseline for LHC Run 4. 		 
poster icon Poster THBP21 [1.286 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP21  
About • Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 31 October 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THBP22 On Liouvillian High Power Beam Accumulation 511
 
  • J.-M. Lagniel
    GANIL, Caen, France
  • M.E. Eshraqi, N. Milaspresenter
    ESS, Lund, Sweden
  
  Funding: This work is co-funded by the European Union
It is acknowledged that the injection of high power proton beams into synchrotrons must be done using stripping injection of H⁻ beams which are accelerated by an injector, as done in many facilities worldwide such as ISIS, JPARC, SNS and CERN. However, this technique is not necessarily the only way of accumulation and in some cases might not represent the best choice. For example in the case of the ESSnuSB Accumulator Ring, accelerating the protons injecting them to the ring could represent savings in capital cost, reduced risk of losses in the linac and transfer lines and simplification to the overall project. This work presents the development of a method allowing to optimize the 4D Liouvillian accumulation of high-power proton and heavy ion beams and finishes with a discussion on the pros and cons of proton injection compared to more traditional H⁻ stripping injection method. 		 
poster icon Poster THBP22 [2.126 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP22  
About • Received ※ 01 October 2023 — Revised ※ 05 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 28 October 2023
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THBP23 Exploring Space Charge and Intra-beam Scattering Effects in the CERN Ion Injector Chain 515
 
  • E. Waagaard
    EPFL, Lausanne, Switzerland
  • H. Bartosik
    CERN, Meyrin, Switzerland
  
  As of today, the LHC ion physics programme is mostly based on Pb ion collisions. The ALICE3 detector proposal requests significantly higher nucleon-nucleon luminosities, as compared to today¿s operation. This improved performance could be potentially achieved with lighter ion species than Pb. In this respect, the CERN Ion Injector chain (consisting of Linac3, LEIR, PS and SPS) will need to provide significantly higher beam intensities with light ion beams as compared to the present ones, whereas operational experience with such beams is limited. We present space charge and intra-beam scattering studies across the Ion Injector chain and strategies to build benchmarked simulation models for optimised ion performance. This is the first step for identifying the ideal ion isotopes and charge states for maximised LHC luminosity production.  
poster icon Poster THBP23 [2.744 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP23  
About • Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 24 October 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THBP24 RCS and Accumulator Rings Designs for ISIS II 519
 
  • D.J. Adams
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • H.V. Cavanagh, I.S.K. Gardner, B.S. Kyle, H. Rafique, C.M. Warsop, R.E. Williamson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK, which provides 0.2 MW of beam power via a 50 Hz, 800 MeV proton RCS. Detailed studies are now underway to find the optimal configuration for a next generation, short-pulsed neutron source that will define a major ISIS upgrade, with construction beginning ~2031. Determining the optimal specification for such a facility is the subject of an ongoing study involving neutron users, target and instrument experts. The accelerator designs being considered for the MW beam powers required, include proposals exploiting FFA rings as well as conventional accumulator and RCS rings. This paper summarises work on physics designs for the conventional rings. Details of lattice designs, injection and extraction systems, correction systems as well as detailed 3D PIC simulations used to ensure 0.1% losses and low foil hits are presented. Designs for a 0.4 to 1.2 GeV RCS and 1.2 GeV AR are outlined. Work on the next stages of the study are also summarised to benchmark and minimise predicted losses, and thus maximise the high intensity limit of designs.  
poster icon Poster THBP24 [3.231 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP24  
About • Received ※ 28 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 22 October 2023
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THBP26
 Applying the Low Energy RHIC Electron Cooler (LEReC) Concept to the High Energy Coolers  
 
  • D. Kayran, A.V. Fedotov, S. Seletskiy
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron cooling is a method to achieve high brightness of hadron beams by reducing emittances of the hadrons. Traditionally, electron coolers based on electrostatic accelerators have been used for low-energy hadron beams. However, this technique is limited by the electron beam energy. RF acceleration of electron bunches enables electron cooling for hadron beams at energies of tens or even hundreds of GeV. A novel electron cooler using RF acceleration (LEReC) was successfully implemented at Brookhaven National Laboratory*. LEReC provided cooling for gold ions at 3.8 and 4.5 GeV/n during the RHIC Low Energy Scan -II, using electron acceleration up to 2 MeV energy. A successful demonstration of cooling using LEReC approach allows us to consider a similar technique for higher energies. An electron cooler for the injection energy of the Electron Ion Collider (EIC) is currently under design, which aims to provide strong cooling for protons at 24 GeV. This requires a high-quality electron beam with a high charge and an energy of 13 MeV. In this report, we present LEReC operational experience and discuss the path forward to the 13 MeV electron cooler for the EIC.
* A. Fedotov et al., Experimental Demonstration of Hadron Beam Cooling Using Radio Frequency Accelerated Electron Bunches, Phys. Rev. Lett. 124, 084801 (2020). 		 
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THBP27 Experimental Investigation of Nonlinear Integrable Optics in a Paul Trap 523
 
  • J.A.D. Flowerdew
    University of Oxford, Oxford, United Kingdom
  • D.J. Kelliher, S. Machida
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • S.L. Sheehy
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  Funding: Work supported by Royal Society grants
Octupoles are often used to damp beam instabilities caused by space charge. However, in general the insertion of octupole magnets leads to a nonintegrable lattice which reduces the area of stable particle motion. One proposed solution to this problem is Quasi-Integrable Optics (QIO), where the octupoles are inserted between a specially designed lattice called a T-insert. An octupole with a strength that scales as 1/β3(s) is applied in the drift region to create a time-independent octupole field, leading to a lattice with an invariant Hamiltonian. This means that large tune spreads can be achieved without reducing the dynamic aperture. IBEX is a Paul trap which confines low energy ions with an RF voltage, simulating the transverse dynamics of an alternating gradient accelerator. IBEX has recently undergone an upgrade to allow for octupole fields to be created in the trap in addition to quadrupole focusing. We present our first experimental results from testing QIO with the IBEX trap.
jake.flowerdew@physics.ox.ac.uk 		 
poster icon Poster THBP27 [4.163 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP27  
About • Received ※ 30 September 2023 — Revised ※ 09 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 31 October 2023
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THBP28 A Phase Trombone for the Fermilab PIP-II Beam Transfer Line 527
 
  • M. Xiao, D.E. Johnson, J.-F. Ostiguy
    Fermilab, Batavia, Illinois, USA
  
  The PIP-II beam transfer line (BTL) transports the beam from the PIP-II Linac to the Booster synchrotron ring. A crucial aspect of the BTL design is the collimation system which play a vital role in removing large ampli-tude particles that may otherwise miss the horizontal and vertical edges of the foil at the point of injection into the Booster. To ensure the effectiveness of the collimators, simulations were conducted to determine optimal place-ment within the BTL. These simulations revealed that precise control of the accumulated phase advances be-tween the collimators and the foil is critical. To achieve fine-tuning of the phase advance, a phase trombone was incorporated within the BTL. This paper presents the design and implementation details of this phase trom-bone  
poster icon Poster THBP28 [0.798 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP28  
About • Received ※ 20 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 30 October 2023
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THBP29 Effects of Cavity Pre-Detuning on RF Power Transients at Injection into the LHC 530
 
  • B.E. Karlsen-Bæck, T. Argyropoulos, A.C. Butterworth, R. Calaga, I. Karpov, H. Timko, M. Zampetakis
    CERN, Meyrin, Switzerland
  
  At injection into the LHC, the RF system is perturbed by beam-induced voltage resulting in strong RF power transients and the instant detuning of the cavities. The automatic tuning system, however, needs time for the mechanical compensation of the resonance frequency to take place. Acting back on the beam, the transients in RF power are expected to limit the maximum injected intensity by generating unacceptable beam loss. Reducing them is therefore essential to reach the target intensity during the High Luminosity (HL) LHC era. At LHC flat bottom, the cavities are operated using the half-detuning beam-loading compensation scheme. As implemented today, the tuner control algorithm starts acting only after the injection of the first longer bunch train which causes the bunches for this injection to experience the largest power spikes. This contribution presents an adapted detuning scheme for the RF cavities before injection. It was proposed as a path to decrease the transients, hence increasing the available intensity margin for the available RF power. The expected gain is evaluated in particle tracking simulations and measurements acquired during operation.  
poster icon Poster THBP29 [3.711 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP29  
About • Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 22 October 2023
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THBP30 Linear Modelling and Lattice Correction from Betatron Phase Measurements at the Fermilab Recycler NOvA Ring 534
 
  • M. Xiao, R. Ainsworth, K.J. Hazelwood, M.-J. Yang
    Fermilab, Batavia, Illinois, USA
  
  Utilizing the measurement of coherent betatron oscilla-tion phase has emerged as a fast and precise approach for identifying and rectifying errors in achieving a desired lattice in CESR (Cornell Electron Storage Ring), using TAO analysis program and BMAD subroutines. One key advantage of betatron phase measurement over ¿ meas-urement is its sensitivity to phase variations between detectors. This software package has been successfully implemented for the Recycler Ring at Fermilab, with the adaptation of different hardware installations. By em-ploying this technique, a linear model of the bare Recy-cler ring was established, enabling the correction of quadrupole errors.  
poster icon Poster THBP30 [1.476 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP30  
About • Received ※ 19 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 27 October 2023
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THBP31 Electron Cloud Effects in the CERN Accelerators in Run 3 538
 
  • L. Mether, H. Bartosik, L. Giacomel, G. Iadarola, S. Johannesson, I. Mases Solé, K. Paraschou, G. Rumolo, L. Sabato, C. Zannini, E. de la Fuente
    CERN, Meyrin, Switzerland
  • S. Johannesson
    EPFL, Lausanne, Switzerland
  
  Several of the machines in the CERN accelerator complex, in particular the Large Hadron Collider (LHC) and the Super Proton Synchrotron (SPS), are prone to the build-up of electron clouds. Electron cloud effects are observed especially when the machines are operated with a 25 ns bunch spacing, which has routinely been used in the LHC since the start of its second operational run in 2015. After the completion of the LHC Injectors Upgrade program during the latest long shutdown period, the machines are currently operated with unprecedented bunch intensity and beam brightness. With the increase in bunch intensity, electron cloud effects have become one of the main performance limitations, as predicted by simulation studies. In this contribution we present the experimental observations of electron cloud effects since 2021 and discuss their implications for the future operation of the complex.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP31  
About • Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 23 October 2023
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THBP32 Xobjects and Xdeps: Low-Level Libraries Empowering Beam Dynamics Simulations 543
 
  • S. Łopaciuk, R. De Maria, G. Iadarola
    CERN, Meyrin, Switzerland
  
  Xobjects and Xdeps are Python libraries included in the Xsuite beam dynamics simulation software package. These libraries are crucial to achieving two of the main goals of Xsuite: speed and ease of use. Xobjects allows users to run simulations on various hardware in a platform-agnostic way: with little user intervention single- and multi-threading is supported as well as GPU computations using both CUDA and OpenCL. Xdeps provides support for deferred expressions in Xsuite. Relations among simulation parameters and functions driving properties of lattice elements can be defined or indeed imported from other tools such as MAD-X and then easily updated before or during the simulation.  
poster icon Poster THBP32 [0.266 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP32  
About • Received ※ 21 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 17 October 2023
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THBP34 PSI Injector II and the 72 MeV Transfer Line: MinT-Simulation vs. Measurements 547
 
  • C. Baumgarten, H. Zhang
    PSI, Villigen PSI, Switzerland
  
  PSI’s Injector II cyclotron is the only cyclotron worldwide that makes use of the so-called "Vortex effect", in which strong space charge forces generate the counter-intuitive effect to "roll up" bunches thus keeping them longitudinally compact. The effect has been verified by bunch shape measurements and the PIC-code OPAL. However, PSI’s new fast matrix code MinT allows to reproduce the Vortex effect by a linear matrix model which is computational much cheaper than PIC simulations, and is suitable for "online use" in Control rooms. Furthermore it provides the second moments of matched distributions.  
poster icon Poster THBP34 [0.840 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP34  
About • Received ※ 30 September 2023 — Revised ※ 03 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 31 October 2023
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THBP35 Analysis Tools for Numerical Simulations of Dynamic Aperture with Xsuite 551
 
  • T. Pugnat, M. Giovannozzi, F.F. Van der Veken
    CERN, Meyrin, Switzerland
  • D. Di Croce
    EPFL, Lausanne, Switzerland
  
  Recently, several efforts have been made at CERN to develop a new tracking tool, Xsuite, which is intended to be the successor to SixTrack. In this framework, analysis tools have also been prepared with the goal of providing advanced post-processing techniques for the interpretation of dynamic aperture simulations. The proposed software suite, named Xdyna, is meant to be a successor to the existing SixDesk environment. It incorporates all recent approaches developed to determine the dynamic aperture for a fixed number of turns. It also enables studying the time evolution of the dynamic aperture and the fitting of rigorous models based on the stability-time estimate provided by the Nekhoroshev theorem. These models make it possible to link the dynamic aperture to beam lifetime, and thus provide very relevant information for the actual performance of particle colliders. These tools have been applied to studies related to the luminosity upgrade of the CERN Large Hadron Collider (HL-LHC), the results of which are presented here.  
poster icon Poster THBP35 [0.514 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP35  
About • Received ※ 28 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 11 October 2023
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THBP36 Study of the Performance of the CERN Proton Synchrotron Internal Dump 555
 
  • T. Pugnat, L.S. Esposito, M. Giovannozzi, C. Hernalsteens, A. Huschauer, S. Niang
    CERN, Meyrin, Switzerland
  • D. Domange, E. Gnacadja, R. Tesse
    ULB, Bruxelles, Belgium
  
  In the framework of the LHC Injector Upgrade project, a new internal dump for the CERN Proton Synchrotron (PS) has been designed, installed, and successfully commissioned. This device is meant to move rapidly into the beam and stop charged particles over several turns to provide protection to the PS hardware against beam-induced damage. The performance of the dump should ensure efficient use throughout the PS energy range, i.e. from injection at 2 GeV (kinetic energy) to flat top at 26 GeV (total energy). In this paper, detailed numerical simulations are presented, carried out with a combination of sophisticated beam dynamics and beam-matter interaction codes, assessing the behaviour of stopped or scattered particles. The results of these numerical simulations are compared with the data collected during the routine operation of the PS and its internal dump.  
poster icon Poster THBP36 [0.609 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP36  
About • Received ※ 26 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 28 October 2023
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THBP37 Refining the LHC Longitudinal Impedance Model 559
 
  • M. Zampetakis, T. Argyropoulos, Y. Brischetto, R. Calaga, L. Giacomel, B.E. Karlsen-Bæck, I. Karpov, I. Karpov, N. Mounet, B. Salvant, H. Timko
    CERN, GENEVA, Switzerland
  • B.E. Karlsen-Bæck
    INFN-Roma, Roma, Italy
  
  Modelling the longitudinal impedance for the Large Hadron Collider (LHC) has been a long-standing effort, especially in view of its High-Luminosity (HL) upgrade. The resulting impedance model is an essential input for beam dynamics studies. Increased beam intensities in the HL-LHC era will pose new challenges like RF power limitations, beam losses at injection and coupled-bunch instabilities throughout the acceleration cycle. Starting from the existing longitudinal impedance model, effort has been made to identify the main contributing devices and improve their modelling. Loss of Landau damping (LLD) simulations are performed to investigate the dependence of the stability threshold on the completeness of the impedance model and its broad-band cut-off frequency. Plans to perform beam measurements to estimate the cut-off frequency, by investigating the LLD threshold in operation, are also discussed.  
poster icon Poster THBP37 [5.606 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP37  
About • Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 14 October 2023
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THBP38 Two-Dimensional Longitudinal Painting at Injection into the CERN PS Booster 563
 
  • S.C.P. Albright, F. Asvesta, B. Bielawski, C. Bracco, P.K. Skowroński, R. Wegner
    CERN, Meyrin, Switzerland
  
  To inject highest beam intensities at the transfer from Linac4 into the four rings of the PS Booster (PSB) at CERN, protons must be accumulated during up to 148 turns in total. With the conventional, fixed chopping pattern this process results in an approximately rectangular distribution in the longitudinal phase space. As the bucket shape in the PSB does not correspond to this distribution, the process leads to longitudinal mismatch, contributing to emittance growth and reduced transmission. The field in the last accelerating cavity of Linac4 can be modulated, which leads to fine corrections of the extracted beam energy. At the same time, the chopping pattern can be varied. Combining both allows injecting a near uniform longitudinal distribution whose boundary corresponds to an iso-Hamiltonian contour of the RF bucket, hence significantly reducing mismatch. In an operational context, the longitudinal painting must be controlled in a way that allows easy intensity variation, and can even require different painting configurations for each of the four PSB rings. This contribution presents the first demonstration of longitudinal painting in the PSB, and its impact on beam performance.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP38  
About • Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 24 October 2023
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THBP39 Advances on LHC RF Power Limitation Studies at Injection 567
 
  • H. Timko, T. Argyropoulos, R. Calaga, N. Catalán Lasheras, K. Iliakis, B.E. Karlsen-Bæck, I. Karpov, M. Zampetakis
    CERN, Meyrin, Switzerland
  
  The average power consumption of the main RF system during beam injection in the High-Luminosity Large Hadron Collider is expected to be close to the maximum available klystron power. Power transients due to the mismatch of the beam and the action of control loops will exceed the available power. This paper presents the most recent estimations of the injection voltage and steady-state power needed for HL-LHC intensities, taking also beam stability into account. It summarises measurement and simulation efforts ongoing to better understand power transients and beam losses, and describes the operational margin to be taken into account for different equipment.  
poster icon Poster THBP39 [0.861 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP39  
About • Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 20 October 2023
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THBP40 Mitigation Strategies for the Instabilities Induced by the Fundamental Mode of the HL-LHC Crab Cavities 571
 
  • L. Giacomel, P. Baudrenghien, X. Buffat, R. Calaga, N. Mounet
    CERN, Meyrin, Switzerland
  
  The transverse impedance is one of the potentially limiting effects for the performance of the High-Luminosity Large Hadron Collider (HL-LHC). In the current LHC, the impedance is dominated by the resistive-wall contribution of the collimators at typical bunch-spectrum frequencies, and is of broad-band nature. Nevertheless, the fundamental mode of the crab cavities, that are a vital part of the HL-LHC baseline, adds a strong and narrow-band contribution. The resulting coupled-bunch instability, which contains a strong head-tail component, requires dedicated mitigation measures, since the efficiency of the transverse damper is limited against such instabilities, and Landau damping from octupoles would not be sufficient. The efficiency and implications of various mitigation strategies, based on RF feedbacks and optics changes, are discussed, along with first measurements using crab cavity prototypes at the Super Proton Synchrotron (SPS).  
poster icon Poster THBP40 [0.461 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP40  
About • Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 19 October 2023
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THBP42 Longitudinal Loss of Landau Damping in Double Harmonic RF Systems below Transition Energy 575
 
  • L. Intelisano, H. Damerau, I. Karpov
    CERN, Meyrin, Switzerland
  
  Landau damping plays a crucial role in ensuring single-bunch stability in hadron synchrotrons. In the longitudinal plane, loss of Landau damping (LLD) occurs when a coherent mode of oscillation moves out of the incoherent synchrotron frequency band. The LLD threshold is studied for a purely inductive impedance below transition energy, specifically considering the common case of double harmonic RF systems operating in counter-phase at the bunch position. The additional focusing force due to beam-induced voltage distorts the potential well, ultimately collapsing the bucket. The limiting conditions for a binomial particle distribution are calculated. Furthermore, the contribution focuses on the configuration of the higher-harmonic RF system at four times the fundamental RF frequency operating in phase. In this case, the LLD threshold shows a non-monotonic behavior with a zero threshold where the derivative of the synchrotron frequency distribution is positive. The findings are obtained employing semi-analytical calculations using the MELODY code.  
poster icon Poster THBP42 [1.710 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP42  
About • Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 14 October 2023
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THBP43 Intensity Effects in a Chain of Muon RCSs 579
 
  • F. Batsch, D. Amorim, H. Damerau, A. Grudiev, I. Karpov, E. Métral, D. Schulte
    CERN, Meyrin, Switzerland
  • A. Chancé
    CEA, Gif-sur-Yvette, France
  • S. Udongwo
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  
  Funding: Funded by the European Union under Grant Agreement n.101094300
The muon collider offers an attractive path to a compact, multi-TeV lepton collider. However, the short muon lifetime leads to stringent requirements on the fast energy increase. While extreme energy gains in the order of several GeV per turn are crucial for a high elevated muon survival rate, ultra-short and intense bunches are needed to achieve large luminosity. The longitudinal beam dynamics of a chain of rapid cycling synchrotrons (RCS) for acceleration from around 60 GeV to several TeV is being investigated in the framework of the International Muon Collider Collaboration. Each RCS must have a distributed radio-frequency (RF) system with several hundred RF stations to establish stable synchrotron motion. In this contribution, the beam-induced voltage in each RCS is studied, assuming a single high-intensity bunch per beam in each direction and ILC-like 1.3 GHz accelerating structures. The impact of single- and multi-turn wakefields on longitudinal stability and RF power requirements is analysed with particle tracking simulations. Special attention is moreover paid to the beam power deposited into the higher-order modes of the RF cavities. 		 
poster icon Poster THBP43 [1.345 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP43  
About • Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023
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THBP44 ImpactX Modeling of Benchmark Tests for Space Charge Validation 583
 
  • C.E. Mitchell, M. Garten, A. Huebl, R. Lehé, J. Qiang, R.T. Sandberg, J.-L. Vay
    LBNL, Berkeley, California, USA
  
  The code ImpactX represents the next generation of the particle-in-cell code IMPACT-Z, featuring s-based symplectic tracking with 3D space charge, parallelism with GPU acceleration, adaptive mesh-refinement, and modernized language features. With such a code comes a renewed need for space charge validation using well-defined benchmarks. For this purpose, the code is continuously checked against a test suite of exactly-solvable problems. The suite includes field calculation tests, dynamical tests involving coasting or stationary beams, and beams matched to periodic focusing channels. To study the long-time multi-turn performance of the code in a more complex setting, we investigate problems involving high-intensity storage rings, such as the GSI benchmark problem for space charge induced trapping. Comparisons against existing codes are made where possible.  
poster icon Poster THBP44 [1.020 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP44  
About • Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 26 October 2023
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THBP45 Longitudinal Collective Effects at Beam Transfer from PS to SPS at CERN 587
 
  • A. Lasheen, H. Damerau, I. Karpov, G. Papotti, E.T. Vinten
    CERN, Meyrin, Switzerland
  
  The hardware upgrades of the LHC Injectors Upgrade (LIU) project at CERN were completed during the Long Shutdown 2 (2019-2021) to prepare the injectors for the beams required by the High Luminosity (HL) LHC. Doubling the bunch intensity leads to new challenges due to collective effects. Although many bottlenecks were already solved, a remaining limitation is the important loss of particles at transfer from the Proton Synchrotron (PS) to the Super Proton Synchrotron (SPS). The maximum transmission achieved since the restart in 2021 is in the order of 90%, yet leading to unnecessary activation of the SPS. The losses are distributed at various instants of the SPS cycle: fast intensity decay right after injection, slow losses along the injection plateau while waiting for multiple injections from the PS, and uncaptured beam removed at start of acceleration. In this contribution, the focus is on longitudinal aspects of transfer losses and more specifically on intensity effects during the non-adiabatic bunch shorting performed in the PS prior to extraction, as well as on the longitudinal mismatch at injection due to misaligned bunch phases in the SPS caused by transient beam loading.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP45  
About • Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 15 October 2023
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THBP46 Simulation of the ESS Proton Beam Window Scattering 591
 
  • E.D. Fackelman, E. Adli, H.E. Gjersdal, K.N. Sjobak
    University of Oslo, Oslo, Norway
  • Y. Levinsen, A. Takibayev, C.A. Thomaspresenter
    ESS, Lund, Sweden
  
  The European Spallation Source produces neutrons used for science by delivering a 5MW proton beam to a tungsten target. The proton beam parameters must remain within a well-defined range during all phases of facility exploitation. The proton beam parameters are measured and monitored by an instrumentation suite, among which are two beam imaging systems. Parameters such as position and beam current density can be calculated from the images, supporting beam tuning and operation. However, one of the two systems may be affected by beam scattering. In this paper, we will focus on modelling the impact of the scattering on the beam on target distribution. The modelling process, involving simulation codes such as Geant4 and two-dimensional convolution in Matlab, is described. Initially, Geant4 simulates a scattered pencil beam. The resulting distribution is fitted and can be used similarly to an instrument response in image processing to model any possible beam distribution. Finally, we discuss the results of the scattered beam imaging model, showing the range of applications of the model and the impact of scattering on the beam parameters.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP46  
About • Received ※ 01 October 2023 — Revised ※ 09 October 2023 — Accepted ※ 14 October 2023 — Issued ※ 21 October 2023
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THBP47 Studies on the Effect of Beam-Coupling Impedance on Schottky Spectra of Bunched Beams 595
 
  • C. Lannoy, D. Alves, K. Łasocha, N. Mounet
    CERN, Meyrin, Switzerland
  • C. Lannoy, T. Pieloni
    EPFL, Lausanne, Switzerland
  
  Schottky monitors can be used for non-invasive beam diagnostics to estimate various bunch characteristics, such as tune, chromaticity, bunch profile or synchrotron frequency distribution. However, collective effects, in particular beam-coupling impedance, can significantly affect Schottky spectra when large bunch charges are involved. In such conditions, the available interpretation methods are difficult to apply directly to the measured spectra, thus preventing the extraction of beam and machine parameters, which is possible for lower bunch charges. To study the impact of impedance on such spectra, we perform here time-domain, macro-particle simulations and apply a semi-analytical method to compute the Schottky signal for various machine and beam conditions, including those corresponding to typical physics operation at the Large Hadron Collider. This study provides preliminary interpretations of the impact of beam-coupling impedance on Schottky spectra by incorporating longitudinal and transverse resonator-like impedance models into the simulations.  
poster icon Poster THBP47 [1.133 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP47  
About • Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 21 October 2023
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THBP48 Latest Advances in Targetry Systems at CERN and Exciting Avenues for Future Endeavours 599
 
  • R. Franqueira Ximenes, O. Aberle, M. Calvianipresenter, R. Esposito, J.L. Grenard, T. Griesemer, A.R. Romero Francia, C. Torregrosa
    CERN, Meyrin, Switzerland
  
  CERN’s accelerator complex offers diverse target systems for a range of scientific pursuits, including varying beam energies, intensities, pulse lengths, and objectives. Future high-intensity fixed target experiments aim to advance this field further. This contribution highlights upgraded operational target systems, enhancing CERN’s physics endeavours. One example is the third-generation nTOF spallation neutron target, using a nitrogen-cooled pure lead system impacted by a 20 GeV/c proton beam. Another focuses on recent antiproton production target upgrades, with a high-intensity 26 GeV/c beam colliding with a narrow-air-cooled iridium target. Looking ahead, new high-power target systems are planned. One aims to discover hidden particles using a 350-kW high-Z production target, while another enhances kaon physics through a 100 kW low-Z target. This article provides an overview of current target systems at CERN, detailing beam-intercepting devices and engineering aspects. It also previews upcoming facilities that could soon be implemented at CERN.  
poster icon Poster THBP48 [63.760 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP48  
About • Received ※ 07 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 10 October 2023
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THBP49 Collimation of 400 MJ Beams at the LHC: The First Step Towards the HL-LHC Era 603
 
  • S. Redaelli, A. Abramov, D.B. Baillard, R. Bruce, R. Cai, F. Carra, M. D’Andrea, M. Di Castro, L. Giacomel, P.D. Hermes, B. Lindström, D. Mirarchi, N. Mounet, F.-X. Nuiry, A. Perillo Marcone, F.F. Van der Veken
    CERN, Meyrin, Switzerland
  • R. Cai
    EPFL, Lausanne, Switzerland
  • A. Vella
    University of Malta, Information and Communication Technology, Msida, Malta
  
  Funding: Work supported by the HL-LHC project.
An important upgrade programme is planned for the collimation system of the CERN Large Hadron Collider (LHC) in order to meet the challenges of the upcoming High-Luminosity LHC (HL-LHC) project. A first stage of the HL-LHC upgrade was already deployed during the last LHC Long Shutdown, offering important improvements of the collimation cleaning, a significant reduction of the impedance contribution and better cleaning of collisional debris, in particular for ion-ion collisions. This upgrade provides a critical opportunity to explore the LHC intensity limits during the LHC Run 3 and can provide crucial feedback to refine upgrade plans and operational scenarios in the HL-LHC era. This paper describes the performance of the upgraded LHC collimation system that has already enabled stored-beam energies larger than 400 MJ at the unprecedented beam energy of 6.8 TeV, and reviews further upgrade plans envisaged to reach 700 MJ beams at the HL-LHC. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP49  
About • Received ※ 03 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 10 October 2023
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THBP50 Fermilab Main Injector and Recycler Operations in the Megawatt Era 607
 
  • A.P. Schreckenberger
    Fermilab, Batavia, Illinois, USA
  
  Significant upgrades to Fermilab¿s accelerator complex have accompanied the development of LBNF and DUNE. These improvements will facilitate 1-MW operation of the NuMI beam for the first time this year through changes to the Recycler slip-stacking procedure and shortening of the Main Injector ramp time. The modifications to the Recycler slip-stacking and effort to reduce the Main Injector ramp time will be discussed. Additionally, details regarding further shortening of the ramp time and the impact on future accelerator operations are presented.  
poster icon Poster THBP50 [0.923 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP50  
About • Received ※ 25 September 2023 — Revised ※ 09 October 2023 — Accepted ※ 12 October 2023 — Issued ※ 12 October 2023
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THBP51
 Commissioning of the RAON Linear Accelerator  
 
  • D. Jeon, J.-H. Jang, H. Jin, H.J. Kim
    IBS, Daejeon, Republic of Korea
  
  In May 2023, the beam commissioning of the RAON superconducting linac was carried out. Beam commissioning results of the RAON linear accelerator are presented.  
poster icon Poster THBP51 [1.421 MB]  
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THBP52 A Python Package to Compute Beam-Induced Heating in Particle Accelerators and Applications 611
 
  • L. Sito, F. Giordano, G. Rumolo, B. Salvant, C. Zannini, E. de la Fuente
    CERN, Meyrin, Switzerland
  
  High-energy particle beams interact electromagnetically with their surroundings when they travel inside an accelerator. These interactions may cause beam-induced heating of the accelerator’s components, which could eventually lead to outgassing, equipment degradation and physical damage. The expected beam-induced heating can be related to the beam coupling impedance, an electromagnetic property of every accelerator device. Accounting for beam-induced heating is crucial both at the design phase of an accelerator component and for gaining an understanding of devices¿ failures. In this paper, an in-house developed Python tool to compute beam-induced heating due to impedance is introduced. The different features and capabilities will be showcased and applied to real devices in the LHC and the injector chain.  
poster icon Poster THBP52 [0.544 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP52  
About • Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 11 October 2023
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THBP53 Commissioning and Operation of the Collimation System at the RCS of CSNS 615
 
  • S.Y. Xu, J. Chen, S. Wang
    IHEP, Beijing, People’s Republic of China
  • K. Zhou
    IHEP CSNS, Guangdong Province, People’s Republic of China
  
  For high-intensity proton synchrotrons, minimizing particle losses during machine operation is essential to avoid radiation damage. Uncontrolled beam loss posed a significant challenge to achieving higher beam intensity and power for high-intensity proton synchrotrons. The beam collimation system can remove halo particles and to localize the beam loss. The use of collimation system is an important means of controlling uncontrolled beam loss in high-power proton accelerators. To reduce the uncontrolled beam loss, a transverse collimation system was designed for the RCS of CSNS. The design transverse collimator is a two-stage collimator. During the beam commissioning of CSNS, the designed two-stage collimator has been changed to one-stage collimator to overcome the problem of low collimation efficiency caused by insufficient phase shift between the primary and secondary collimators. By optimizing the collimation system, the beam loss is well localized in the collimator area, effectively reducing uncontrolled beam loss. The beam power of CSNS achieved the design value of 100 kW with small uncontrolled beam loss.  
poster icon Poster THBP53 [0.780 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP53  
About • Received ※ 30 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 10 October 2023
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THBP54
 Synchronization of PVs From Different IOC  
 
  • M.T. Li
    IHEP CSNS, Guangdong Province, People’s Republic of China
  • Y.L. Zhang
    IHEP, Beijing, People’s Republic of China
  
  PVs generated from different IOCs may have different timestamps. The difference may exert a profound counter-effect during operations and beam commissioning. Then synchronizing this infomation would become a important issue. In this work we will introduce the Illusions triggered by the out-of-sync, and give some improvements.  
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THBP55 Commissioning of NICA Injection Complex 618
 
  • V.A. Lebedev, O.I. Brovko, A.V. Butenko, E.E. Donets, B.V. Golovenskiy, E.V. Gorbachev, S.A. Kostromin, K.A. Levterov, I.N. Meshkov, A.S. Sergeev, M.M. Shandov, A.O. Sidorin, V.L. Smirnov, E. Syresin, A. Tuzikov
    JINR, Dubna, Moscow Region, Russia
  • I. Nikolaichuk, A.Yu. Ramsdorf
    JINR/VBLHEP, Dubna, Moscow region, Russia
  
  The Nuclotron-based Ion Collider fAcility (NICA) is under construction at JINR. The NICA project goal is to provide colliding beams for studies of collisions of heavy fully stripped ions and light p¿lairized ions. The NICA Collider includes two rings with 503 m circumference each and the injection complex. For the heavy ion mode, the injection complex consists of following accelerators: 3.2 MeV/u linac (HILAC), 600 MeV/u (A/Z=6) superconducting booster synchrotron (Booster) and main superconducting synchrotron (Nuclotron) with kinetic energy up to 3.9 GeV/u (A/Z=2.5). The injection complex has been under commissioning for more than 2 years. Its Run IV was carried from October 2022 to February of 2023. It was aimed on the injection complex preparation for the collider operations in the heavy ion mode. Additionally, the slowly extracted 3.9 GeV/u xenon beam was delivered to the BM&N experiment resulting in 250 million events in the detector. The paper discusses main results of the injection complex commissioning and plans for its further development. The beam commissioning of the collider is expected in the 2nd half of 2025.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP55  
About • Received ※ 26 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 17 October 2023
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THBP57 A Novel RF Power Source for the ESS-Bilbao Ion Source 621
 
  • S. Masa, I. Bustinduypresenter, P.J. González, A. Kaftoosian, L.C. Medina, R. Miracoli, S. Varnasseri
    ESS Bilbao, Zamudio, Spain
  
  This paper presents the improvements in the ESS Bilbao Proton Ion Source by replacing the amplified radio frequency (RF) pulse of a Klystron-based amplification system using a Solid-State Power Amplifier (SSPA). This new amplification system is based on a 1kW SSPA (2.7 GHz), a Compact-RIO (cRIO) device, a voltage-controlled RF attenuator and auxiliary electronics. The Experimental Physics and Industrial Control System (EPICS) serves as distributed control system (DCS) for controlling and monitoring the data required to achieve a 1.5 ms flat and stable pulse at repetition rate of 14 Hz. The following lines describe the structural and control system changes done in the ion source due to the addition of the SSPA-based amplification system, along with the results of the proton beam extraction tests that demonstrate how this system can serve as a viable substitute for the Klystron-based amplification system.  
poster icon Poster THBP57 [2.265 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP57  
About • Received ※ 28 September 2023 — Accepted ※ 09 October 2023 — Issued ※ 26 October 2023  
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THBP58
 Advancing Beam Energy Absorption in the Large Hadron Collider: Evolution of Beam Dumps Design and Operation From LHC Construction to High Luminosity LHC  
 
  • M. Calviani, A.P. Bernardes, C. Bracco, E.M. Farina, R. Franqueira Ximenes, D. Grenier, E. Grenier-Boley, K. Kershaw, A. Lechner, A. Perillo, N. Solieripresenter
    CERN, Meyrin, Switzerland
  
  Two 6-tonne beam dumps are employed to absorb the energy of the two Large Hadron Collider (LHC) intense 7 TeV/c proton beams. Originally designed to handle approximately 300 MJ of energy deposited per dump event, the capacity of these dumps has grown over the lifespan of the LHC due to upgrades aimed at enhancing the machine’s scientific potential. In the era of the High Luminosity LHC (HL-LHC), the dumps will need to withstand energy absorptions of up to 700 MJ per dump. Several upgrades and interventions, such as adjustments to the outer vessel and supporting structure as well as enhancements to online instrumentation, have been executed since the initial installation of the beam dumps. In addition, significant advancements in simulation techniques have been implemented to gain a deeper understanding of the intricate dynamics of high-energy beam absorption and the resulting thermo-mechanical repercussions. Lessons learnt have been acquired also thanks to a first-of-a-kind autopsy. This contribution will present a comprehensive overview of the design, operational experiences, and evolutionary journey of the main absorber within the Large Hadron Collider.  
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THBP59 Tomographic Longitudinal Phase Space Reconstruction of Bunch Compression at ISIS 625
 
  • B.S. Kyle, H.V. Cavanagh, A. Seville, R.E. Williamson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  ISIS is an 800 MeV, high intensity, rapid-cycling synchrotron (RCS) used as a driver for a spallation neutron and muon spectroscopy (¿SR) facility. The intensity-limited beam and RCS operation at ISIS poses significant challenges, with non-adiabatic acceleration and space charge forces resulting in distortions to the Hamiltonian longitudinal dynamics. Effective modelling of the machine and benchmarking of models with beam measurements is essential both to improving machine performance, and to the development of the proposed ISIS II facility. The tomographic principle is a well-established tool for the reconstruction of the longitudinal phase space (LPS) of synchrotron beams. Is it operationally desirable for the ISIS accelerator to provide longitudinally compressed proton beams for ¿SR instrumentation. A new bunch compression scheme has been developed and validated using tomography. A reconstruction of the LPS of the ISIS high-intensity proton beam is presented, along with accompanying benchmarking measurements and beam physics simulations.  
poster icon Poster THBP59 [0.907 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP59  
About • Received ※ 01 October 2023 — Revised ※ 09 October 2023 — Accepted ※ 20 October 2023 — Issued ※ 25 October 2023
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