HB2023 - Classification: Beam Dynamics in Rings

Paper	Title	Page
MOA1I1	Beam Performance with the LHC Injectors Upgrade	1
	G. Rumolo, S.C.P. Albright, R. Alemany-Fernández, M.E. Angoletta, C. Antuono, T. Argyropoulos, F. Asvesta, M.J. Barnes, H. Bartosik, P. Baudrenghien, G. Bellodi, N. Biancacci, C. Bracco, N. Bruchon, E. Carlier, J. Coupard, H. Damerau, G.P. Di Giovanni, A. Findlay, M.A. Fraser, A. Funken, R. Garoby, S.S. Gilardoni, B. Goddard, G. Hagmann, K. Hanke, A. Huschauer, G. Iadarola, V. Kain, I. Karpov, J.-B. Lallement, A. Lasheen, T.E. Levens, K.S.B. Li, A.M. Lombardi, E.H. Maclean, D. Manglunki, I. Mases Solé, M. Meddahi, L. Mether, B. Mikulec, E. Montesinos, Y. Papaphilippou, G. Papotti, K. Paraschou, C. Pasquino, F. Pedrosa, T. Prebibaj, S. Prodon, D. Quartullo, F. Roncarolo, B. Salvant, M. Schenk, R. Scrivens, E.N. Shaposhnikova, L. Sito, P.K. Skowroński, A. Spierer, R. Steerenberg, M. Sullivan, F.M. Velotti, R. Veness, C. Vollinger, R. Wegner, C. Zannini, E. de la Fuente CERN, Meyrin, Switzerland T. Prebibaj IAP, Frankfurt am Main, Germany
	The LHC Injectors Upgrade (LIU) project was put in place between 2010 and 2021 to increase the intensity and brightness in the LHC injectors to match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring reliable operation of the injectors complex up to the end of the HL-LHC era (ca. 2040). During the 2019-2020 CERN accelerators shutdown, extensive hardware modifications were implemented in the entire LHC proton and ion injection chains, involving the new Linac4, the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) and the ion PS injectors, i.e. the Linac3 and the Low Energy Ion Ring (LEIR). Since 2021, beams have been recommissioned throughout the injectors’ chain and the beam parameters are being gradually ramped up to meet the LIU specifications using new beam dynamics solutions adapted to the upgraded accelerators. This paper focuses on the proton beams and describes the current state of the art.
	Slides MOA1I1 [10.002 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-MOA1I1
About •	Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 18 October 2023
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MOA3I1	Beam Dynamics Challenges in the Design of the Electron-Ion Collider	23
	Y. Luo, M. Blaskiewicz, D. Marx, E. Wang, F.J. Willeke BNL, Upton, New York, USA A. Blednykh, C. Montag, V. Ptitsyn, V.H. Ranjbar, S. Verdú-Andrés Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA S. Nagaitsev JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The Electron-Ion Collider (EIC), presently under construction at Brookhaven National Laboratory, will collide polarized high-energy electron beams with hadron beams, achieving luminosities up to 1 × 10³⁴ cm^¿2 s^¿1 in the center-of-mass energy range of 20-140 GeV. To achieve such high luminosity, we adopt high bunch intensities for both beams, small and flat transverse beam sizes at the interaction point (IP), a large crossing angle of 25 mrad, and a novel strong hadron cooling in the Hadron Storage Ring (HSR) to counteract intra-beam scattering (IBS) at the collision energy. In this talk, we will review the beam dynamics challenges in the design of the EIC, particularly the single-particle dynamic aperture, polarization maintenance, beam-beam interaction, impedance budget and instabilities. We will also briefly mention some technical challenges associated with beam dynamics, such as strong hadron cooling, multipoles and noises of crab cavities, power supply current ripples, and the vacuum upgrade to existing beam pipes of the Hadron Storage Ring of the EIC.
	Slides MOA3I1 [3.437 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-MOA3I1
About •	Received ※ 02 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 18 October 2023
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MOA4I2	Space-charge Limits and Possible Mitigation Approaches in the FAIR Synchrotrons
	A. Oeftiger, O. Boine-Frankenheim GSI, Darmstadt, Germany
	To fully exploit the potential of the new Facility for Antiproton and Ion Research (FAIR), the key synchrotrons SIS18 and SIS100 should be operated at the "space charge limit" for light- and heavy-ion beams at a tolerable low beam loss of a few percent per cycle. A detailed 3D tracking model with collective effects (space charge and impedance) has been established including a realistic magnet field error model and the Landau Damping octupoles. The error model for SIS100 is based on precise bench measurements of the main magnets, the one for SIS18 on a novel data-driven beam-based approach named Deep Lie Map Network. Simulations of the full one-second SIS100 accumulation plateau determine the maximum achievable bunch intensity and the corresponding low-loss working point region. Several mitigation approaches have been scrutinised for their impact on the space charge limit: beta-beat correction to suppress the half-integer resonance, bunch flattening via double harmonic RF, and pulsed electron lenses (e-lenses). An optimum configuration for pulsed e-lens operation has been determined, options for additional coherent stabilisation as a Landau damping e-lens are currently studied.
	Slides MOA4I2 [3.697 MB]
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MOA4I3	Collective Effects in Lepton Circular Colliders and Synchrotron Light Sources
	M. Zobov LNF-INFN, Frascati, Italy M. Migliorati INFN-Roma1, Rome, Italy
	In this seminar we discuss differences and similarities in beam dynamics of high current and high brightness beams in lepton and hadron circular accelerators. A particular attention is given to an interplay of different collective phenomena affecting the lepton machine performance.
	Slides MOA4I3 [2.914 MB]
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TUA1I1	Inverse Stability Problem in Beam Dynamics
	A.V. Burov Fermilab, Batavia, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. Beam stability is conventionally described by means of the stability diagram, which is a threshold line in a complex plane of a particular intensity parameter, the coherent tune shift; the diagram separates stable and unstable states. The incoherent tune spread of the beam particles normally causes the transverse stability diagram to be an asymmetric bell-shaped curve above the real axis; for a given optical nonlinearity, the diagram is determined by the beam distribution function only. Recently, such a diagram was measured by means of an antidamper, see S. Antipov et al., Phys. Rev. Lett. 126, 164801 (2021). Such measurements open the door to a new method of beam diagnostics, finding the beam phase space density as a solution of an inverse stability problem. The main idea, methods of its implementation, possible obstacles and optimizations are discussed.
	Slides TUA1I1 [0.761 MB]
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TUA1I2	New Understanding of Longitudinal Beam Instabilities and Comparison with Measurements	45
	I. Karpov CERN, Meyrin, Switzerland
	Beam instabilities driven by broad- and narrowband impedance sources have been treated separately so far. In this contribution, we present the generalised beam stability analysis based on the concept of van Kampen modes. In the presence of broadband impedance, the loss of Landau damping (LLD) in the longitudinal plane can occur above a certain single-bunch intensity. For significantly higher intensities, the broad-band impedance can drive violent radial or azimuthal mode-coupling instabilities. We have shown that the synchrotron frequency spread due to RF field non-linearity, counter-intuitively, reduces the single-bunch instability threshold. We have also demonstrated that a multi-bunch instability driven by a narrow-band impedance source can be significantly affected by LLD when adding broad-band impedance. These findings are supported by macroparticle simulations and beam observations in the Super Proton Synchrotron and the Large Hadron Collider at CERN.
	Slides TUA1I2 [1.517 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA1I2
About •	Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 13 October 2023
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TUA1C1	Major Longitudinal Impedance Sources in the J-PARC Main Ring	53
	A. Kobayashi KEK, Tokai, Ibaraki, Japan
	Beam intensity upgrade is ongoing at the J-PARC main ring. The beam instability is controlled by feedback systems in both longitudinal and transverse directions respectively. However, in recent years, microbunch structures have been observed during debunching, inducing electron cloud and transverse beam instability, which has become a problem. It is essential to identify the cause and take countermeasures. A summary of model and measurement comparisons will be reported for the major impedances RF-cavities, FX-septa, and FX-kickers. Of the five septa, two have been subjected to impedance reduction measures. The remaining three septa are of different types, but similar measures are planning.
	Slides TUA1C1 [26.758 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA1C1
About •	Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 18 October 2023
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TUA1C2	Coherent Dispersion Effects in 2-D Coasting Beams and 3-D Bunched Beams in High-Intensity Hadron Synchrotrons
	Y.S. Yuan IHEP, Beijing, People’s Republic of China G. Franchetti GSI, Darmstadt, Germany
	Both space charge and dispersion have an effect on high intensity beams in circular accelerators or transport sections with bending magnets, and may lead to emittance growth or even beam loss. In this work we study the combined effect of dispersion and space charge on both 2-D and 3-D high-intensity beams. Based on 2-D envelope equations extended by dispersion, and particle-in-cell simulations, we investigate the mismatched oscillation and coherent instabilities in an rms self-consistent manner. Main characteristics of the space-charge modified dispersion are discussed. It is found that the parametric and confluent resonances in 90 deg envelope insatiability can be separated because of dispersion. The recently-discovered 120 deg dispersion instability is also detailed discussed. For 3-D bunched beams, a splitting effect on dispersion mode and side bands of envelope modes due to synchrotron motion are presented. The mechanism of the splitting effect on the dispersion mode with space charge is analyzed. Moreover, the 120 deg dispersion instability in the 3-D bunched beam are presented with a discussion on possible methods for measuring the dispersion mode in hadron synchrotrons.
	Slides TUA1C2 [1.499 MB]
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TUA2I1	Xsuite: An Integrated Beam Physics Simulation Framework	73
	G. Iadarola, A. Abramov, X. Buffat, R. De Maria, D. Demetriadou, L. Deniau, P.D. Hermes, P. Kicsiny, P.M. Kruyt, A. Latina, S. Łopaciuk, L. Mether, K. Paraschou, T. Pieloni, G. Sterbini, F.F. Van der Veken CERN, Meyrin, Switzerland P. Belanger UBC & TRIUMF, Vancouver, British Columbia, Canada D. Di Croce, M. Seidel, L. van Riesen-Haupt EPFL, Lausanne, Switzerland P.J. Niedermayer GSI, Darmstadt, Germany
	Xsuite is a newly developed modular simulation package combining in a single flexible and modern framework the capabilities of different tools developed at CERN in the past decades, notably Sixtrack, Sixtracklib, COMBI and PyHEADTAIL. The suite is made of a set of python modules (Xobjects, Xparts, Xtrack, Xcoll, Xfields, Xdpes) that can be flexibly combined together and with other accelerator-specific and general-purpose python tools to study complex simulation scenarios. The code allows for symplectic modeling of the particle dynamics, combined with the effect of synchrotron radiation, impedances, feedbacks, space charge, electron cloud, beam-beam, beamstrahlung, electron lenses. For collimation studies, beam-matter interaction is simulated using the K2 scattering model or interfacing Xsuite with the BDSIM/Geant4 library. Tools are available to compute the accelerator optics functions from the tracking model and to generate particle distributions matched to the optics. Different computing platforms are supported, including conventional CPUs, as well as GPUs from different vendors.
	Slides TUA2I1 [4.388 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2I1
About •	Received ※ 30 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 22 October 2023
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TUA2I2	Community Modeling Tools for High Brightness Beam Physics	81
	C.E. Mitchell, M. Garten, A. Huebl, R. Lehé, J. Qiang, R.T. Sandberg, J.-L. Vay LBNL, Berkeley, California, USA
	Pushing accelerator technology toward operation with higher intensity hadron beams is critical to meet the needs of future colliders, spallation neutron sources, and neutrino sources. To understand the dynamics of such beams requires a community effort with a comprehensive approach to modeling, from the source to the end of the beam lifetime. One needs efficient numerical models with high spatial resolution and particle statistics, insensitivity to numerical noise, and the ability to resolve low-density halo and particle loss. To meet these challenges, LBNL and collaborators have seeded an open ecosystem of codes, the Beam pLasma & Accelerator Simulation Toolkit (BLAST), that can be combined with each other and with machine learning frameworks to enable integrated start-to-end simulation of accelerator beamlines for accelerator design. Examples of BLAST tools include the PIC codes WarpX and ImpactX. These codes feature GPU acceleration and mesh-refinement, and have openPMD standardized data I/O and a Python interface. We describe these tools and the advantages that open community standards provide to inform the modeling and operation of future high-brightness accelerators.
	Slides TUA2I2 [13.597 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2I2
About •	Received ※ 03 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 01 November 2023
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TUA2C1	Beam-Beam Effects: Modelling, Measurements and Correction Strategy on the Luminosity Calibration Measurements at the Large Hadron Collider Experiments
	T. Pieloni, J.M. Wańczyk EPFL, Lausanne, Switzerland X. Buffat, A.E. Dabrowski, R. Tomás García, J.M. Wańczyk CERN, Meyrin, Switzerland W. Kozanecki CEA, Gif-sur-Yvette, France D.P. Stickland PU, Princeton, New Jersey, USA
	At the Large Hadron Collider (LHC), absolute luminosity calibrations obtained by the van der Meer (vdM) method and operational luminosity variations during physics fills are biased by the mutual electromagnetic interaction of the two beams, the beam-beam effects. The colliding bunches experience relative orbit shifts, optical distortions as well as transverse distribution deviations from Gaussians that must be accounted and corrected for when deriving the absolute luminosity scale and when monitoring detector performances during physics runs. In this study the impact of beam-beam effects on the absolute luminosity measurements will be shown by means of numerical simulations, together with the associated systematic uncertainties to the visible cross sections. The biases to the absolute calibrations are also described together with the correction scheme developed and used as part of the detector data analysis. Simulation studies will be compared to data collected during a dedicated experimental study with the CMS, ATLAS and ALICE detectors. Models and experimental data are compared at 1% level, showing an impressive agreement between numerical expectations and experimental data.
	Slides TUA2C1 [3.967 MB]
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TUA2C2	Recent Advances in the CERN PS Impedance Model and Instability Simulations	86
	S. Joly La Sapienza University of Rome, Rome, Italy G. Iadarola, N. Mounet, B. Salvant, C. Zannini CERN, Meyrin, Switzerland M. Migliorati INFN-Roma1, Rome, Italy
	Transverse instability growth rates in the CERN Proton Synchrotron are studied thanks to the recently updated impedance model of the machine. Using this model, macroparticle tracking simulations were performed with a new method well-suited for the slicing of short wakes, which achieves comparable performance to the originally implemented method while reducing the required number of slices by a factor of 5 to 10. Dedicated beam-based measurement campaigns were carried out to benchmark the impedance model. Until now, the model underestimated instability growth rates at injection energy. Thanks to a recent addition to the impedance model, namely the kicker magnets¿ connecting cables and their external circuits, the simulated instability growth rates are now comparable to the measured ones.
	Slides TUA2C2 [0.736 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2C2
About •	Received ※ 28 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 21 October 2023
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WEA1I1	Development and Application of High-Performance CISP-GPU Code for High Intensity Effects in HIAF
	J. Liu, S.H. Du, C.Guo. Guo, J.C. Yang, G. Zhu IMP/CAS, Lanzhou, People’s Republic of China
	Funding: National Natural Science Foundation of China (Grant No. 12005274) HIAF project is a major national science and technology infrastructure project in China. Its booster ring BRing can provide high intensity ion beams from proton to uranium, in which high intensity effects could have many detrimental impacts on the intensity and quality. And situations become more complicated as diverse effects like impedances, space charge fields, complex beam manipulations, etc., are coupled. A new high-performance simulation code CISP-GPU, which is driven by an object-oriented and GPU computing integrated framework, is developed for the BRing of HIAF and other high intensity ion accelerators to simulate all high intensity effects and their coupling effects with other dynamics, aiming at more comprehensive mapping between simulations and practical facilities. Now, the CISP-GPU has been applied widely to the dynamics research of the BRing, including analyzing and stabilizing collective instabilities, correcting resonances from space charge effects and nonlinear errors, and so on. In the future, the CISP-GPU will be integrated in the control system of HIAF and extended to a powerful platform which can simulate all vital effects in diverse synchrotrons and colliders.
	Slides WEA1I1 [9.644 MB]
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WEA1I2	Analytical and Numerical Studies on Kicked Beams in the Context of Half-Integer Studies	188
	G. Franchetti GSI, Darmstadt, Germany F. Asvesta, H. Bartosik, T. Prebibaj CERN, Meyrin, Switzerland
	In the context of the half-integer studies an investigation of the dynamics of the kicked beam has revealed surprising properties. The coupling of space charge with chromatic- ity in addition to usual damping/non-damping dynamics, exhibits new properties typical of a linear coupling. This proceeding covers the status of these studies carried out with analytical and numerical approaches and the prelimi- nary results of experimental investigations in the CERN PS Booster.
	Slides WEA1I2 [24.966 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA1I2
About •	Received ※ 02 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 24 October 2023
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WEA1C1	Bunch-by-bunch Tune Shift Studies for LHC-type Beams in the CERN SPS	194
	I. Mases Solé, H. Bartosik, K. Paraschou, M. Schenk, C. Zannini CERN, Meyrin, Switzerland
	After the implementation of major upgrades as part of the LHC Injector Upgrade Project (LIU), the Super Proton Synchrotron (SPS) delivers high intensity bunch trains with 25 ns bunch spacing to the Large Hadron Collider (LHC). These beams are exposed to several collective effects in the SPS, such as beam coupling impedance, space charge and electron cloud, leading to relatively large bunch-by-bunch coherent and incoherent tune shifts. Tune correction to the nominal values at injection is crucial to ensure beam stability and good beam transmission. Measurements of the bunch-by-bunch coherent tune shifts have been performed under different beam conditions. In this paper, we present the measurements of the bunch-by-bunch tune shift as function of bunch intensity for trains of 72 bunches. The experimental data are compared to multiparticle tracking simulations (including other beam variants such as 8b4e beam and hybrid beams) using the SPS impedance model.
	Slides WEA1C1 [2.613 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA1C1
About •	Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 09 October 2023
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WEA1C2	Design of a Proof-of-Principle Experiment for the DLMN Method to Identify Magnetic Field Errors
	C. Caliari TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim, A. Oeftiger GSI, Darmstadt, Germany
	Magnetic field errors limit the beam intensity in synchrotrons as they excite nonsystematic resonances, reduce dynamic aperture, and may result in beam loss due to space charge induced resonance crossing. Methods to establish a field error model from beam-based measurements are therefore a valuable tool for realistic limitation and improvement studies. We report on the implementation of a proof-of-principle experiment in the GSI synchrotron SIS18 to identify both linear and non-linear field errors. The goal is to demonstrate the Deep Lie Map Network (DLMN) technique, a proposed data-driven approach based on (unstructured) turn-by-turn BPM data. Established identification procedures in the literature are based on orbit or tune response matrices, or resonance driving terms. While they sequentially build a field error model for subsequent accelerator sections, the DLMN approach could save valuable beam time by detecting field errors in parallel. We underline the potential of the DLMN method via detailed simulation studies to infer gradient and sextupole errors. The outline of a proof-of-principle experiment is discussed upon first experimental experience.
	Slides WEA1C2 [1.439 MB]
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WEA2I1	Compensation of Third-order Resonances in the High Intensity Regime	215
	C.E. Gonzalez-Ortiz MSU, East Lansing, Michigan, USA R. Ainsworth Fermilab, Batavia, Illinois, USA P.N. Ostroumov FRIB, East Lansing, Michigan, USA
	As the Fermilab Accelerator Complex enters the high-intensity era, the Recycler Ring (RR) needs to mitigate the detrimental effect of third-order resonance crossing. Third-order resonance lines can be compensated to first order by cancelling out the global Resonance Driving Terms (RDTs) using the response matrix method. This compensation scheme has been proven to work at low intensities, i.e., in the single-particle regime. In order to evaluate the effectiveness of this compensation scheme at higher intensities, this study looks at dynamic and static tune scans, with and without resonance compensation, and different space charge tune shifts. Special care was taken in order to disentangle effects from space charge tune shift, structure resonances and space charge driven resonances.
	Slides WEA2I1 [6.714 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA2I1
About •	Received ※ 02 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 09 October 2023
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WEA2I2	Space Charge Induced Resonances and Suppression in J-PARC MR	222
	T. Yasui KEK, Tokai, Ibaraki, Japan
	In the main ring synchrotron (MR) of Japan Proton Accelerator Research Complex (J-PARC), space charge induced resonances are the cause of beam losses. Although we have scanned the tunes to minimize beam losses, it has been difficult to completely avoid high order structure resonances because the MR has only three super-periodicities. In the present settings for the neutrino operation, we identified that the space charge induced resonance 8ny=171 is the main source of beam losses, except for random resonances. We found that this resonance can be suppressed by beam optics modification while maintaining the tune. In this talk, we present the theoretical, simulation, and experimental results showing the advantages of the new beam optics and the reasons for them.
	Slides WEA2I2 [6.189 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA2I2
About •	Received ※ 07 November 2023 — Accepted ※ 18 November 2023 — Issued ※ 29 November 2023
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WEA2C1	Tune Optimization for Alleviating Space Charge Effects and Suppressing Beam Instability in the RCS of CSNS	228
	S.Y. Xu, L. Huang, M.Y. Huang, Y. Li, S. Wang IHEP, Beijing, People’s Republic of China
	The design betatron tune of the Rapid Cycling Synchrotron (RCS) of China Spallation Neutron Source (CSNS) is (4.86, 4.80), which allows for incoherent tune shifts to avoid serious systematic betatron resonances. When the operational bare tune was set at the design value, serious beam instability in the horizontal plane and beam loss induced by half-integer resonance in the vertical plane under space charge detuning were observed. The tunes over the whole acceleration process are optimized based on space charge effects and beam instability. In the RCS, manipulating the tune during the beam acceleration process is a challenge due to the quadrupole magnets being powered by resonant circuits. In the RCS of CSNS, a method of waveform compensation for RCS magnets was investigated to accurately manipulate the magnetic field ramping process. The optimized tune pattern was able to well control the beam loss induced by space charge and beam instability. The beam power of CSNS achieved the design value of 100 kW with small uncontrolled beam loss.
	Slides WEA2C1 [4.710 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA2C1
About •	Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 23 October 2023
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WEA2C2	Measurement of Transverse Statistical Dependence for Non-Gaussian Beam Distributions via Resonances in the CERN PSB	231
	E.R. Lamb, F. Asvesta, H. Bartosik, G. Sterbini CERN, Meyrin, Switzerland E.R. Lamb EPFL, Lausanne, Switzerland
	This work addresses the origins and the effects of the statistical dependence in non-Gaussian beam distributions with the ultimate goal to identify the most representative case for tracking simulations across the CERN accelerator complex. Starting from the observation that non-Gaussian heavy-tailed transverse beam profiles can be reconstructed from 4D phase space distributions under two different conditions (statistical independence or dependence in the x-y plane), we consider space charge dominated beams interacting with the lattice nonlinear resonances to perform measurements to study the mechanisms that lead to non-Gaussian distributions. Finally, we explore the beam dynamics implications of the above hypotheses in terms of dependent loss processes across the transverse planes.
	Slides WEA2C2 [1.249 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA2C2
About •	Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 21 October 2023
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THA1I1	Performance and Upgrade Considerations for the CSNS Injection	326
	M.Y. Huang, S. Wang, S.Y. Xu IHEP, Beijing, People’s Republic of China
	Funding: This work is jointly supported by the National Natural Science Foundation of China (Nos. 12075134) and the Guangdong Basic and Applied Basic Research Foundation (No. 2021B1515120021). For the proton synchrotron, the beam injection is one of the most important issues. Firstly, based on the China Spallation Neutron Source (CSNS), the injection methods have been comprehensively studied, including phase space painting and H⁻ stripping. In order to solve the key difficulties faced when the beam power exceeds 50% of the design value, flexibility in the CSNS design has been exploited to implement the correlated painting by using the rising current curve of the pulse power supply. The effectiveness of the new method has been verified in the simulation and beam commissioning. By using the new method, the beam power on the target has successfully risen to the design value. Secondly, for the CSNS upgrade, the injection energy is increased from 80 MeV to 300 MeV and the injection beam power is increased by about 19 times. Based on the CSNS experience and simulation results, it is hoped that the new injection scheme can not only be compatible with correlated and anti-correlated painting, but also greatly reduces the peak temperature of the stripping foil. After in-depth study, a new painting scheme has been proposed which has been verified to be feasible in the simulation.
	Slides THA1I1 [2.951 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1I1
About •	Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 15 October 2023
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THA1I2	High-Intensity Studies on the ISIS RCS and Their Impact on the Design of ISIS-II	331
	R.E. Williamson, D.J. Adams, H.V. Cavanagh, B.S. Kyle, D.W. Posthuma de Boer, H. Rafique, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation centres on a rapid cycling proton synchrotron (RCS) that accelerates 3·10¹³ protons per pulse from 70 MeV to 800 MeV at 50 Hz, delivering a mean beam power of 0.2 MW. As a high-intensity machine, research at ISIS is predominantly focused on understanding, minimising and controlling beam-loss, which is central to sustainable machine operation. Knowledge of beam-loss mechanisms then informs the design of future high power accelerators such as ISIS-II. This paper provides an overview of the R&D studies currently underway on the ISIS RCS and how these relate to ongoing work understanding and optimising designs for ISIS-II. In particular, recent extensive investigations into observed head-tail instabilities are summarised.
	Slides THA1I2 [10.825 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1I2
About •	Received ※ 01 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 18 October 2023
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THA1I3	Predominantly Electric Storage Ring with Nuclear Spin Control Capability	338
	R.M. Talman Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	A predominantly electric storage ring with weak superimposed magnetic bending is shown to be capable of storing two different nuclear isotope bunches, such as helion and deuteron, co-traveling with different velocities on the same central orbit. ‘‘Rear-end’’ collisions occurring periodically in a full acceptance particle detector/polarimeter, allow the (previously inaccessible) direct measurement of the spin dependence of nuclear transmutation for center of mass (CM) kinetic energies ranging from hundreds of keV up toward pion production thresholds. These are ‘‘rear-end collisions’’ occurring as faster stored bunches pass through slower bunches. An inexpensive facility capable of meeting these requirements is described, with nuclear channel h + d arrow α + p as example.
	Slides THA1I3 [0.860 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1I3
About •	Received ※ 07 December 2023 — Accepted ※ 11 December 2023 — Issued ※ 25 December 2023
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THA1C1	High Intensity Beam Dynamics Challenges for HL-LHC	344
	N. Mounet, H. Bartosik, P. Baudrenghien, R. Bruce, X. Buffat, R. Calaga, R. De Maria, C.N. Droin, L. Giacomel, M. Giovannozzi, G. Iadarola, S. Kostoglou, B. Lindström, L. Mether, E. Métral, Y. Papaphilippou, K. Paraschou, S. Redaelli, G. Rumolo, B. Salvant, G. Sterbini, R. Tomás García CERN, Meyrin, Switzerland
	The High Luminosity (HL-LHC) project aims to increase the integrated luminosity of CERN’s Large Hadron Collider (LHC) by an order of magnitude compared to its initial design. This requires a large increase in bunch intensity and beam brightness compared to the first LHC runs, and hence poses serious collective-effects challenges, related in particular to electron cloud, instabilities from beam-coupling impedance, and beam-beam effects. Here we present the associated constraints and the proposed mitigation measures to achieve the baseline performance of the upgraded LHC machine. We also discuss the interplay of these mitigation measures with other aspects of the accelerator, such as the physical and dynamic aperture, machine protection, magnet imperfections, optics, and the collimation system.
	Slides THA1C1 [3.385 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1C1
About •	Received ※ 01 October 2023 — Revised ※ 10 October 2023 — Accepted ※ 12 October 2023 — Issued ※ 15 October 2023
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THAFP01	Probing Transverse Impedances in the High Frequency Range at the CERN SPS	393
	E. de la Fuente, H. Bartosik, I. Mases Solé, G. Rumolo, C. Zannini CERN, Meyrin, Switzerland
	Funding: CERN The SPS transverse impedance model, which includes the major impedance contributions in the machine, can be benchmarked through measurements of the Head-Tail mode zero instability. Since the SPS works above transition energy, the head tail mode zero is unstable for negative values of chromaticity. The measured instability growth rate is proportional to the real part of the transverse impedance. Studies performed after the LHC Injectors Upgrade (LIU) showed a relevant impedance around 2 GHz with high-gamma transition optics (Q26). This paper presents the follow-up studies to probe the behavior of this beam coupling impedance contribution.
	Slides THAFP01 [2.262 MB]
	Poster THAFP01 [1.149 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP01
About •	Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023
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THAFP02	Resonance Extraction Research Based on China Spallation Neutron Source	397
	Y.W. An, L. Huang, Z.P. Li, S.Y. Xu, Y.S. Yuan IHEP, Beijing, People’s Republic of China
	Resonance extraction based on the RCS ring is an important aspect of beam applications. This article proposes a new design of resonance extraction based on the CSNS-RCS ring. By adjusting parameters such as the skew sextupole magnet, beam working point, RF-Kicker, etc., the simulation results from PyOrbit demonstrate the ability to rapidly extract a large number of protons within a few turns.
	Slides THAFP02 [1.497 MB]
	Poster THAFP02 [0.960 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP02
About •	Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 01 November 2023
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THAFP03	Measurement of Stability Diagram at IOTA at Fermilab	400
	M.K. Bossard, Y.K. Kim University of Chicago, Chicago, Illinois, USA R. Ainsworth, N. Eddy Fermilab, Batavia, Illinois, USA
	Funding: Fermilab Nonlinear focusing elements can enhance the stability of particle beams in high-energy colliders by means of Landau Damping, through the tune spread which is introduced. We propose an experiment at Fermilab’s Integrable Optics Test Accelerator (IOTA) to investigate the influence of nonlinear focusing elements on the transverse stability of the beam. In this experiment, we employ an anti-damper, an active transverse feedback system, as a controlled mechanism to induce coherent beam instability. By utilizing the anti-damper, we can examine the impact of the nonlinear focusing element on the beam’s transverse stability. The stability diagram, a tool used to determine the system’s stability, will be measured using a recently demonstrated method at the LHC. This measurement is carried out experimentally by selecting specific threshold gains and measuring them for a range of phases. The stability diagram is represented by gei¿ on the complex plane. The experiment at IOTA adds insight towards the stability diagram measurement method by supplying a reduced machine impedance, to investigate the impedance’s effect on the stability diagram, as well as a larger range of phase measurements.
	Slides THAFP03 [1.331 MB]
	Poster THAFP03 [1.692 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP03
About •	Received ※ 06 October 2023 — Revised ※ 09 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 12 October 2023
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THAFP04	Investigation of Tail-dominated Instability in the Fermilab Recycler Ring	403
	O. Mohsen, R. Ainsworth, A.V. Burov Fermilab, Batavia, Illinois, USA
	In our recent operational run, a single bunch, tail-dominated instability was observed in the Fermilab Recycler ring. This instability exclusively occurs in the vertical plane when the chromaticity is close to zero. In this study, we conduct a detailed analysis of this instability under different operational parameters. We investigate the impact of space charge on the head-tail motion and propose potential interpretations of the underlying mechanism of the instability. Moreover, we explore methods to mitigate this instability in the future.
	Slides THAFP04 [1.429 MB]
	Poster THAFP04 [0.892 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP04
About •	Received ※ 25 September 2023 — Revised ※ 09 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 29 October 2023
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THAFP05	A Wireless Method for Beam Coupling Impedance Measurements of the LHC Goniometer	407
	C. Antuono, C. Zannini CERN, Meyrin, Switzerland M. Migliorati, A. Mostacci LNF-INFN, Frascati, Italy
	The beam coupling impedance (BCI) of an accelerator component should be ideally evaluated exciting the device with the beam itself. However, this scenario is not always attainable and alternative methods must be exploited, such as the bench measurements techniques. The stretched Wire Method (WM) is a well established technique for BCI evaluations, although nowadays its limitations are well known. In particular, the stretched wire perturbs the electromagnetic boundary conditions. Therefore, the results obtained could be inaccurate, especially below the cut-off frequency of the beam pipe in the case of cavity-like structures. To overcome these limitations, efforts are being made to investigate alternative bench measurement techniques that will not require the modification of the device under test (DUT). In this framework, a wireless method has been identified and tested for a pillbox cavity. Its potential for more complex structures, such as the LHC crystal goniometer is explored.
	Slides THAFP05 [1.088 MB]
	Poster THAFP05 [1.151 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP05
About •	Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 11 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 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 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 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 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 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 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 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 2Q_y=9 in order to avoid emittance blow-up from resonances at Q_x,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 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
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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 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
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THBP22	On Liouvillian High Power Beam Accumulation	511
	J.-M. Lagniel GANIL, Caen, France M.E. Eshraqi, N. Milas 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 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 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
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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 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 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 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 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 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
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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 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 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 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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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 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 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 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 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 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 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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FRA1I3	EIC cooling
	V. Litvinenko BNL, Upton, New York, USA
	Future Electron-Ion Collider (EIC) at BNL would rely on strong cooling of ion and protons beams to reach its design luminosity. In this talk I will discuss number of options for cooling hadron beams in EIC. Main challenge for EIC cooling is to provide cooling of intense proton beam with sufficient cooling decrement and sufficient margins for errors. I will focus on capabilities as well as on challenges of various cooling techniques to fit this challenge.
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FRA2I1	Summary of the Working Group A: Beam Dynamics in Rings	662
	H. Bartosik, G. Rumolo CERN, Meyrin, Switzerland J.-L. Vay LBNL, Berkeley, California, USA N. Wang IHEP, Beijing, People’s Republic of China
	The HB-2023 workshop at CERN from October 9 to 13, 2023 is the continuation of the series of workshops, which started in 2002 at FNAL and rotates every two years between America, Europe and Asia. This contribution summarises the main highlights from Working Group A, Beam Dynamics in Rings, in terms of progress and challenges in the achievement of ever higher intensity and brightness hadron beams in accelerator rings around the world.
	Slides FRA2I1 [4.325 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-FRA2I1
About •	Received ※ 04 December 2023 — Accepted ※ 05 December 2023 — Issued ※ 01 January 2024
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Paper

Title

Page

Beam Performance with the LHC Injectors Upgrade

1

G. Rumolo, S.C.P. Albright, R. Alemany-Fernández, M.E. Angoletta, C. Antuono, T. Argyropoulos, F. Asvesta, M.J. Barnes, H. Bartosik, P. Baudrenghien, G. Bellodi, N. Biancacci, C. Bracco, N. Bruchon, E. Carlier, J. Coupard, H. Damerau, G.P. Di Giovanni, A. Findlay, M.A. Fraser, A. Funken, R. Garoby, S.S. Gilardoni, B. Goddard, G. Hagmann, K. Hanke, A. Huschauer, G. Iadarola, V. Kain, I. Karpov, J.-B. Lallement, A. Lasheen, T.E. Levens, K.S.B. Li, A.M. Lombardi, E.H. Maclean, D. Manglunki, I. Mases Solé, M. Meddahi, L. Mether, B. Mikulec, E. Montesinos, Y. Papaphilippou, G. Papotti, K. Paraschou, C. Pasquino, F. Pedrosa, T. Prebibaj, S. Prodon, D. Quartullo, F. Roncarolo, B. Salvant, M. Schenk, R. Scrivens, E.N. Shaposhnikova, L. Sito, P.K. Skowroński, A. Spierer, R. Steerenberg, M. Sullivan, F.M. Velotti, R. Veness, C. Vollinger, R. Wegner, C. Zannini, E. de la Fuente
CERN, Meyrin, Switzerland
T. Prebibaj
IAP, Frankfurt am Main, Germany

The LHC Injectors Upgrade (LIU) project was put in place between 2010 and 2021 to increase the intensity and brightness in the LHC injectors to match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring reliable operation of the injectors complex up to the end of the HL-LHC era (ca. 2040). During the 2019-2020 CERN accelerators shutdown, extensive hardware modifications were implemented in the entire LHC proton and ion injection chains, involving the new Linac4, the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) and the ion PS injectors, i.e. the Linac3 and the Low Energy Ion Ring (LEIR). Since 2021, beams have been recommissioned throughout the injectors’ chain and the beam parameters are being gradually ramped up to meet the LIU specifications using new beam dynamics solutions adapted to the upgraded accelerators. This paper focuses on the proton beams and describes the current state of the art.

Slides MOA1I1 [10.002 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-MOA1I1

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Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 18 October 2023

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MOA3I1

Beam Dynamics Challenges in the Design of the Electron-Ion Collider

23

Y. Luo, M. Blaskiewicz, D. Marx, E. Wang, F.J. Willeke
BNL, Upton, New York, USA
A. Blednykh, C. Montag, V. Ptitsyn, V.H. Ranjbar, S. Verdú-Andrés
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
S. Nagaitsev
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Electron-Ion Collider (EIC), presently under construction at Brookhaven National Laboratory, will collide polarized high-energy electron beams with hadron beams, achieving luminosities up to 1 × 10³⁴ cm^¿2 s^¿1 in the center-of-mass energy range of 20-140 GeV. To achieve such high luminosity, we adopt high bunch intensities for both beams, small and flat transverse beam sizes at the interaction point (IP), a large crossing angle of 25 mrad, and a novel strong hadron cooling in the Hadron Storage Ring (HSR) to counteract intra-beam scattering (IBS) at the collision energy. In this talk, we will review the beam dynamics challenges in the design of the EIC, particularly the single-particle dynamic aperture, polarization maintenance, beam-beam interaction, impedance budget and instabilities. We will also briefly mention some technical challenges associated with beam dynamics, such as strong hadron cooling, multipoles and noises of crab cavities, power supply current ripples, and the vacuum upgrade to existing beam pipes of the Hadron Storage Ring of the EIC.

Slides MOA3I1 [3.437 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-MOA3I1

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Received ※ 02 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 18 October 2023

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MOA4I2

Space-charge Limits and Possible Mitigation Approaches in the FAIR Synchrotrons

A. Oeftiger, O. Boine-Frankenheim
GSI, Darmstadt, Germany

To fully exploit the potential of the new Facility for Antiproton and Ion Research (FAIR), the key synchrotrons SIS18 and SIS100 should be operated at the "space charge limit" for light- and heavy-ion beams at a tolerable low beam loss of a few percent per cycle. A detailed 3D tracking model with collective effects (space charge and impedance) has been established including a realistic magnet field error model and the Landau Damping octupoles. The error model for SIS100 is based on precise bench measurements of the main magnets, the one for SIS18 on a novel data-driven beam-based approach named Deep Lie Map Network. Simulations of the full one-second SIS100 accumulation plateau determine the maximum achievable bunch intensity and the corresponding low-loss working point region. Several mitigation approaches have been scrutinised for their impact on the space charge limit: beta-beat correction to suppress the half-integer resonance, bunch flattening via double harmonic RF, and pulsed electron lenses (e-lenses). An optimum configuration for pulsed e-lens operation has been determined, options for additional coherent stabilisation as a Landau damping e-lens are currently studied.

Slides MOA4I2 [3.697 MB]

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MOA4I3

Collective Effects in Lepton Circular Colliders and Synchrotron Light Sources

M. Zobov
LNF-INFN, Frascati, Italy
M. Migliorati
INFN-Roma1, Rome, Italy

In this seminar we discuss differences and similarities in beam dynamics of high current and high brightness beams in lepton and hadron circular accelerators. A particular attention is given to an interplay of different collective phenomena affecting the lepton machine performance.

Slides MOA4I3 [2.914 MB]

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TUA1I1

Inverse Stability Problem in Beam Dynamics

A.V. Burov
Fermilab, Batavia, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Beam stability is conventionally described by means of the stability diagram, which is a threshold line in a complex plane of a particular intensity parameter, the coherent tune shift; the diagram separates stable and unstable states. The incoherent tune spread of the beam particles normally causes the transverse stability diagram to be an asymmetric bell-shaped curve above the real axis; for a given optical nonlinearity, the diagram is determined by the beam distribution function only. Recently, such a diagram was measured by means of an antidamper, see S. Antipov et al., Phys. Rev. Lett. 126, 164801 (2021). Such measurements open the door to a new method of beam diagnostics, finding the beam phase space density as a solution of an inverse stability problem. The main idea, methods of its implementation, possible obstacles and optimizations are discussed.

Slides TUA1I1 [0.761 MB]

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TUA1I2

New Understanding of Longitudinal Beam Instabilities and Comparison with Measurements

45

I. Karpov
CERN, Meyrin, Switzerland

Beam instabilities driven by broad- and narrowband impedance sources have been treated separately so far. In this contribution, we present the generalised beam stability analysis based on the concept of van Kampen modes. In the presence of broadband impedance, the loss of Landau damping (LLD) in the longitudinal plane can occur above a certain single-bunch intensity. For significantly higher intensities, the broad-band impedance can drive violent radial or azimuthal mode-coupling instabilities. We have shown that the synchrotron frequency spread due to RF field non-linearity, counter-intuitively, reduces the single-bunch instability threshold. We have also demonstrated that a multi-bunch instability driven by a narrow-band impedance source can be significantly affected by LLD when adding broad-band impedance. These findings are supported by macroparticle simulations and beam observations in the Super Proton Synchrotron and the Large Hadron Collider at CERN.

Slides TUA1I2 [1.517 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA1I2

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Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 13 October 2023

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TUA1C1

Major Longitudinal Impedance Sources in the J-PARC Main Ring

53

A. Kobayashi
KEK, Tokai, Ibaraki, Japan

Beam intensity upgrade is ongoing at the J-PARC main ring. The beam instability is controlled by feedback systems in both longitudinal and transverse directions respectively. However, in recent years, microbunch structures have been observed during debunching, inducing electron cloud and transverse beam instability, which has become a problem. It is essential to identify the cause and take countermeasures. A summary of model and measurement comparisons will be reported for the major impedances RF-cavities, FX-septa, and FX-kickers. Of the five septa, two have been subjected to impedance reduction measures. The remaining three septa are of different types, but similar measures are planning.

Slides TUA1C1 [26.758 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA1C1

About •

Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 18 October 2023

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TUA1C2

Coherent Dispersion Effects in 2-D Coasting Beams and 3-D Bunched Beams in High-Intensity Hadron Synchrotrons

Y.S. Yuan
IHEP, Beijing, People’s Republic of China
G. Franchetti
GSI, Darmstadt, Germany

Both space charge and dispersion have an effect on high intensity beams in circular accelerators or transport sections with bending magnets, and may lead to emittance growth or even beam loss. In this work we study the combined effect of dispersion and space charge on both 2-D and 3-D high-intensity beams. Based on 2-D envelope equations extended by dispersion, and particle-in-cell simulations, we investigate the mismatched oscillation and coherent instabilities in an rms self-consistent manner. Main characteristics of the space-charge modified dispersion are discussed. It is found that the parametric and confluent resonances in 90 deg envelope insatiability can be separated because of dispersion. The recently-discovered 120 deg dispersion instability is also detailed discussed. For 3-D bunched beams, a splitting effect on dispersion mode and side bands of envelope modes due to synchrotron motion are presented. The mechanism of the splitting effect on the dispersion mode with space charge is analyzed. Moreover, the 120 deg dispersion instability in the 3-D bunched beam are presented with a discussion on possible methods for measuring the dispersion mode in hadron synchrotrons.

Slides TUA1C2 [1.499 MB]

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TUA2I1

Xsuite: An Integrated Beam Physics Simulation Framework

73

G. Iadarola, A. Abramov, X. Buffat, R. De Maria, D. Demetriadou, L. Deniau, P.D. Hermes, P. Kicsiny, P.M. Kruyt, A. Latina, S. Łopaciuk, L. Mether, K. Paraschou, T. Pieloni, G. Sterbini, F.F. Van der Veken
CERN, Meyrin, Switzerland
P. Belanger
UBC & TRIUMF, Vancouver, British Columbia, Canada
D. Di Croce, M. Seidel, L. van Riesen-Haupt
EPFL, Lausanne, Switzerland
P.J. Niedermayer
GSI, Darmstadt, Germany

Xsuite is a newly developed modular simulation package combining in a single flexible and modern framework the capabilities of different tools developed at CERN in the past decades, notably Sixtrack, Sixtracklib, COMBI and PyHEADTAIL. The suite is made of a set of python modules (Xobjects, Xparts, Xtrack, Xcoll, Xfields, Xdpes) that can be flexibly combined together and with other accelerator-specific and general-purpose python tools to study complex simulation scenarios. The code allows for symplectic modeling of the particle dynamics, combined with the effect of synchrotron radiation, impedances, feedbacks, space charge, electron cloud, beam-beam, beamstrahlung, electron lenses. For collimation studies, beam-matter interaction is simulated using the K2 scattering model or interfacing Xsuite with the BDSIM/Geant4 library. Tools are available to compute the accelerator optics functions from the tracking model and to generate particle distributions matched to the optics. Different computing platforms are supported, including conventional CPUs, as well as GPUs from different vendors.

Slides TUA2I1 [4.388 MB]

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reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2I1

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Received ※ 30 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 22 October 2023

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TUA2I2

Community Modeling Tools for High Brightness Beam Physics

81

C.E. Mitchell, M. Garten, A. Huebl, R. Lehé, J. Qiang, R.T. Sandberg, J.-L. Vay
LBNL, Berkeley, California, USA

Pushing accelerator technology toward operation with higher intensity hadron beams is critical to meet the needs of future colliders, spallation neutron sources, and neutrino sources. To understand the dynamics of such beams requires a community effort with a comprehensive approach to modeling, from the source to the end of the beam lifetime. One needs efficient numerical models with high spatial resolution and particle statistics, insensitivity to numerical noise, and the ability to resolve low-density halo and particle loss. To meet these challenges, LBNL and collaborators have seeded an open ecosystem of codes, the Beam pLasma & Accelerator Simulation Toolkit (BLAST), that can be combined with each other and with machine learning frameworks to enable integrated start-to-end simulation of accelerator beamlines for accelerator design. Examples of BLAST tools include the PIC codes WarpX and ImpactX. These codes feature GPU acceleration and mesh-refinement, and have openPMD standardized data I/O and a Python interface. We describe these tools and the advantages that open community standards provide to inform the modeling and operation of future high-brightness accelerators.

Slides TUA2I2 [13.597 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2I2

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Received ※ 03 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 01 November 2023

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TUA2C1

Beam-Beam Effects: Modelling, Measurements and Correction Strategy on the Luminosity Calibration Measurements at the Large Hadron Collider Experiments

T. Pieloni, J.M. Wańczyk
EPFL, Lausanne, Switzerland
X. Buffat, A.E. Dabrowski, R. Tomás García, J.M. Wańczyk
CERN, Meyrin, Switzerland
W. Kozanecki
CEA, Gif-sur-Yvette, France
D.P. Stickland
PU, Princeton, New Jersey, USA

At the Large Hadron Collider (LHC), absolute luminosity calibrations obtained by the van der Meer (vdM) method and operational luminosity variations during physics fills are biased by the mutual electromagnetic interaction of the two beams, the beam-beam effects. The colliding bunches experience relative orbit shifts, optical distortions as well as transverse distribution deviations from Gaussians that must be accounted and corrected for when deriving the absolute luminosity scale and when monitoring detector performances during physics runs. In this study the impact of beam-beam effects on the absolute luminosity measurements will be shown by means of numerical simulations, together with the associated systematic uncertainties to the visible cross sections. The biases to the absolute calibrations are also described together with the correction scheme developed and used as part of the detector data analysis. Simulation studies will be compared to data collected during a dedicated experimental study with the CMS, ATLAS and ALICE detectors. Models and experimental data are compared at 1% level, showing an impressive agreement between numerical expectations and experimental data.

Slides TUA2C1 [3.967 MB]

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TUA2C2

Recent Advances in the CERN PS Impedance Model and Instability Simulations

86

S. Joly
La Sapienza University of Rome, Rome, Italy
G. Iadarola, N. Mounet, B. Salvant, C. Zannini
CERN, Meyrin, Switzerland
M. Migliorati
INFN-Roma1, Rome, Italy

Transverse instability growth rates in the CERN Proton Synchrotron are studied thanks to the recently updated impedance model of the machine. Using this model, macroparticle tracking simulations were performed with a new method well-suited for the slicing of short wakes, which achieves comparable performance to the originally implemented method while reducing the required number of slices by a factor of 5 to 10. Dedicated beam-based measurement campaigns were carried out to benchmark the impedance model. Until now, the model underestimated instability growth rates at injection energy. Thanks to a recent addition to the impedance model, namely the kicker magnets¿ connecting cables and their external circuits, the simulated instability growth rates are now comparable to the measured ones.

Slides TUA2C2 [0.736 MB]

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reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2C2

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Received ※ 28 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 21 October 2023

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WEA1I1

Development and Application of High-Performance CISP-GPU Code for High Intensity Effects in HIAF

J. Liu, S.H. Du, C.Guo. Guo, J.C. Yang, G. Zhu
IMP/CAS, Lanzhou, People’s Republic of China

Funding: National Natural Science Foundation of China (Grant No. 12005274)
HIAF project is a major national science and technology infrastructure project in China. Its booster ring BRing can provide high intensity ion beams from proton to uranium, in which high intensity effects could have many detrimental impacts on the intensity and quality. And situations become more complicated as diverse effects like impedances, space charge fields, complex beam manipulations, etc., are coupled. A new high-performance simulation code CISP-GPU, which is driven by an object-oriented and GPU computing integrated framework, is developed for the BRing of HIAF and other high intensity ion accelerators to simulate all high intensity effects and their coupling effects with other dynamics, aiming at more comprehensive mapping between simulations and practical facilities. Now, the CISP-GPU has been applied widely to the dynamics research of the BRing, including analyzing and stabilizing collective instabilities, correcting resonances from space charge effects and nonlinear errors, and so on. In the future, the CISP-GPU will be integrated in the control system of HIAF and extended to a powerful platform which can simulate all vital effects in diverse synchrotrons and colliders.

Slides WEA1I1 [9.644 MB]

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WEA1I2

Analytical and Numerical Studies on Kicked Beams in the Context of Half-Integer Studies

188

G. Franchetti
GSI, Darmstadt, Germany
F. Asvesta, H. Bartosik, T. Prebibaj
CERN, Meyrin, Switzerland

In the context of the half-integer studies an investigation of the dynamics of the kicked beam has revealed surprising properties. The coupling of space charge with chromatic- ity in addition to usual damping/non-damping dynamics, exhibits new properties typical of a linear coupling. This proceeding covers the status of these studies carried out with analytical and numerical approaches and the prelimi- nary results of experimental investigations in the CERN PS Booster.

Slides WEA1I2 [24.966 MB]

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reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA1I2

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Received ※ 02 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 24 October 2023

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WEA1C1

Bunch-by-bunch Tune Shift Studies for LHC-type Beams in the CERN SPS

194

I. Mases Solé, H. Bartosik, K. Paraschou, M. Schenk, C. Zannini
CERN, Meyrin, Switzerland

After the implementation of major upgrades as part of the LHC Injector Upgrade Project (LIU), the Super Proton Synchrotron (SPS) delivers high intensity bunch trains with 25 ns bunch spacing to the Large Hadron Collider (LHC). These beams are exposed to several collective effects in the SPS, such as beam coupling impedance, space charge and electron cloud, leading to relatively large bunch-by-bunch coherent and incoherent tune shifts. Tune correction to the nominal values at injection is crucial to ensure beam stability and good beam transmission. Measurements of the bunch-by-bunch coherent tune shifts have been performed under different beam conditions. In this paper, we present the measurements of the bunch-by-bunch tune shift as function of bunch intensity for trains of 72 bunches. The experimental data are compared to multiparticle tracking simulations (including other beam variants such as 8b4e beam and hybrid beams) using the SPS impedance model.

Slides WEA1C1 [2.613 MB]

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reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA1C1

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Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 09 October 2023

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WEA1C2

Design of a Proof-of-Principle Experiment for the DLMN Method to Identify Magnetic Field Errors

C. Caliari
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim, A. Oeftiger
GSI, Darmstadt, Germany

Magnetic field errors limit the beam intensity in synchrotrons as they excite nonsystematic resonances, reduce dynamic aperture, and may result in beam loss due to space charge induced resonance crossing. Methods to establish a field error model from beam-based measurements are therefore a valuable tool for realistic limitation and improvement studies. We report on the implementation of a proof-of-principle experiment in the GSI synchrotron SIS18 to identify both linear and non-linear field errors. The goal is to demonstrate the Deep Lie Map Network (DLMN) technique, a proposed data-driven approach based on (unstructured) turn-by-turn BPM data. Established identification procedures in the literature are based on orbit or tune response matrices, or resonance driving terms. While they sequentially build a field error model for subsequent accelerator sections, the DLMN approach could save valuable beam time by detecting field errors in parallel. We underline the potential of the DLMN method via detailed simulation studies to infer gradient and sextupole errors. The outline of a proof-of-principle experiment is discussed upon first experimental experience.

Slides WEA1C2 [1.439 MB]

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WEA2I1

Compensation of Third-order Resonances in the High Intensity Regime

215

C.E. Gonzalez-Ortiz
MSU, East Lansing, Michigan, USA
R. Ainsworth
Fermilab, Batavia, Illinois, USA
P.N. Ostroumov
FRIB, East Lansing, Michigan, USA

As the Fermilab Accelerator Complex enters the high-intensity era, the Recycler Ring (RR) needs to mitigate the detrimental effect of third-order resonance crossing. Third-order resonance lines can be compensated to first order by cancelling out the global Resonance Driving Terms (RDTs) using the response matrix method. This compensation scheme has been proven to work at low intensities, i.e., in the single-particle regime. In order to evaluate the effectiveness of this compensation scheme at higher intensities, this study looks at dynamic and static tune scans, with and without resonance compensation, and different space charge tune shifts. Special care was taken in order to disentangle effects from space charge tune shift, structure resonances and space charge driven resonances.

Slides WEA2I1 [6.714 MB]

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reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA2I1

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Received ※ 02 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 09 October 2023

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WEA2I2

Space Charge Induced Resonances and Suppression in J-PARC MR

222

T. Yasui
KEK, Tokai, Ibaraki, Japan

In the main ring synchrotron (MR) of Japan Proton Accelerator Research Complex (J-PARC), space charge induced resonances are the cause of beam losses. Although we have scanned the tunes to minimize beam losses, it has been difficult to completely avoid high order structure resonances because the MR has only three super-periodicities. In the present settings for the neutrino operation, we identified that the space charge induced resonance 8ny=171 is the main source of beam losses, except for random resonances. We found that this resonance can be suppressed by beam optics modification while maintaining the tune. In this talk, we present the theoretical, simulation, and experimental results showing the advantages of the new beam optics and the reasons for them.

Slides WEA2I2 [6.189 MB]

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reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA2I2

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Received ※ 07 November 2023 — Accepted ※ 18 November 2023 — Issued ※ 29 November 2023

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WEA2C1

Tune Optimization for Alleviating Space Charge Effects and Suppressing Beam Instability in the RCS of CSNS

228

S.Y. Xu, L. Huang, M.Y. Huang, Y. Li, S. Wang
IHEP, Beijing, People’s Republic of China

The design betatron tune of the Rapid Cycling Synchrotron (RCS) of China Spallation Neutron Source (CSNS) is (4.86, 4.80), which allows for incoherent tune shifts to avoid serious systematic betatron resonances. When the operational bare tune was set at the design value, serious beam instability in the horizontal plane and beam loss induced by half-integer resonance in the vertical plane under space charge detuning were observed. The tunes over the whole acceleration process are optimized based on space charge effects and beam instability. In the RCS, manipulating the tune during the beam acceleration process is a challenge due to the quadrupole magnets being powered by resonant circuits. In the RCS of CSNS, a method of waveform compensation for RCS magnets was investigated to accurately manipulate the magnetic field ramping process. The optimized tune pattern was able to well control the beam loss induced by space charge and beam instability. The beam power of CSNS achieved the design value of 100 kW with small uncontrolled beam loss.

Slides WEA2C1 [4.710 MB]

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reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA2C1

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Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 23 October 2023

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WEA2C2

Measurement of Transverse Statistical Dependence for Non-Gaussian Beam Distributions via Resonances in the CERN PSB

231

E.R. Lamb, F. Asvesta, H. Bartosik, G. Sterbini
CERN, Meyrin, Switzerland
E.R. Lamb
EPFL, Lausanne, Switzerland

This work addresses the origins and the effects of the statistical dependence in non-Gaussian beam distributions with the ultimate goal to identify the most representative case for tracking simulations across the CERN accelerator complex. Starting from the observation that non-Gaussian heavy-tailed transverse beam profiles can be reconstructed from 4D phase space distributions under two different conditions (statistical independence or dependence in the x-y plane), we consider space charge dominated beams interacting with the lattice nonlinear resonances to perform measurements to study the mechanisms that lead to non-Gaussian distributions. Finally, we explore the beam dynamics implications of the above hypotheses in terms of dependent loss processes across the transverse planes.

Slides WEA2C2 [1.249 MB]

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reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA2C2

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Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 21 October 2023

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THA1I1

Performance and Upgrade Considerations for the CSNS Injection

326

M.Y. Huang, S. Wang, S.Y. Xu
IHEP, Beijing, People’s Republic of China

Funding: This work is jointly supported by the National Natural Science Foundation of China (Nos. 12075134) and the Guangdong Basic and Applied Basic Research Foundation (No. 2021B1515120021).
For the proton synchrotron, the beam injection is one of the most important issues. Firstly, based on the China Spallation Neutron Source (CSNS), the injection methods have been comprehensively studied, including phase space painting and H⁻ stripping. In order to solve the key difficulties faced when the beam power exceeds 50% of the design value, flexibility in the CSNS design has been exploited to implement the correlated painting by using the rising current curve of the pulse power supply. The effectiveness of the new method has been verified in the simulation and beam commissioning. By using the new method, the beam power on the target has successfully risen to the design value. Secondly, for the CSNS upgrade, the injection energy is increased from 80 MeV to 300 MeV and the injection beam power is increased by about 19 times. Based on the CSNS experience and simulation results, it is hoped that the new injection scheme can not only be compatible with correlated and anti-correlated painting, but also greatly reduces the peak temperature of the stripping foil. After in-depth study, a new painting scheme has been proposed which has been verified to be feasible in the simulation.

Slides THA1I1 [2.951 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1I1

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Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 15 October 2023

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THA1I2

High-Intensity Studies on the ISIS RCS and Their Impact on the Design of ISIS-II

331

R.E. Williamson, D.J. Adams, H.V. Cavanagh, B.S. Kyle, D.W. Posthuma de Boer, H. Rafique, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation centres on a rapid cycling proton synchrotron (RCS) that accelerates 3·10¹³ protons per pulse from 70 MeV to 800 MeV at 50 Hz, delivering a mean beam power of 0.2 MW. As a high-intensity machine, research at ISIS is predominantly focused on understanding, minimising and controlling beam-loss, which is central to sustainable machine operation. Knowledge of beam-loss mechanisms then informs the design of future high power accelerators such as ISIS-II. This paper provides an overview of the R&D studies currently underway on the ISIS RCS and how these relate to ongoing work understanding and optimising designs for ISIS-II. In particular, recent extensive investigations into observed head-tail instabilities are summarised.

Slides THA1I2 [10.825 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1I2

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Received ※ 01 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 18 October 2023

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THA1I3

Predominantly Electric Storage Ring with Nuclear Spin Control Capability

338

R.M. Talman
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

A predominantly electric storage ring with weak superimposed magnetic bending is shown to be capable of storing two different nuclear isotope bunches, such as helion and deuteron, co-traveling with different velocities on the same central orbit. ‘‘Rear-end’’ collisions occurring periodically in a full acceptance particle detector/polarimeter, allow the (previously inaccessible) direct measurement of the spin dependence of nuclear transmutation for center of mass (CM) kinetic energies ranging from hundreds of keV up toward pion production thresholds. These are ‘‘rear-end collisions’’ occurring as faster stored bunches pass through slower bunches. An inexpensive facility capable of meeting these requirements is described, with nuclear channel h + d arrow α + p as example.

Slides THA1I3 [0.860 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1I3

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Received ※ 07 December 2023 — Accepted ※ 11 December 2023 — Issued ※ 25 December 2023

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THA1C1

High Intensity Beam Dynamics Challenges for HL-LHC

344

N. Mounet, H. Bartosik, P. Baudrenghien, R. Bruce, X. Buffat, R. Calaga, R. De Maria, C.N. Droin, L. Giacomel, M. Giovannozzi, G. Iadarola, S. Kostoglou, B. Lindström, L. Mether, E. Métral, Y. Papaphilippou, K. Paraschou, S. Redaelli, G. Rumolo, B. Salvant, G. Sterbini, R. Tomás García
CERN, Meyrin, Switzerland

The High Luminosity (HL-LHC) project aims to increase the integrated luminosity of CERN’s Large Hadron Collider (LHC) by an order of magnitude compared to its initial design. This requires a large increase in bunch intensity and beam brightness compared to the first LHC runs, and hence poses serious collective-effects challenges, related in particular to electron cloud, instabilities from beam-coupling impedance, and beam-beam effects. Here we present the associated constraints and the proposed mitigation measures to achieve the baseline performance of the upgraded LHC machine. We also discuss the interplay of these mitigation measures with other aspects of the accelerator, such as the physical and dynamic aperture, machine protection, magnet imperfections, optics, and the collimation system.

Slides THA1C1 [3.385 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THA1C1

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Received ※ 01 October 2023 — Revised ※ 10 October 2023 — Accepted ※ 12 October 2023 — Issued ※ 15 October 2023

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THAFP01

Probing Transverse Impedances in the High Frequency Range at the CERN SPS

393

E. de la Fuente, H. Bartosik, I. Mases Solé, G. Rumolo, C. Zannini
CERN, Meyrin, Switzerland

Funding: CERN
The SPS transverse impedance model, which includes the major impedance contributions in the machine, can be benchmarked through measurements of the Head-Tail mode zero instability. Since the SPS works above transition energy, the head tail mode zero is unstable for negative values of chromaticity. The measured instability growth rate is proportional to the real part of the transverse impedance. Studies performed after the LHC Injectors Upgrade (LIU) showed a relevant impedance around 2 GHz with high-gamma transition optics (Q26). This paper presents the follow-up studies to probe the behavior of this beam coupling impedance contribution.

Slides THAFP01 [2.262 MB]

Poster THAFP01 [1.149 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP01

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Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023

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THAFP02

Resonance Extraction Research Based on China Spallation Neutron Source

397

Y.W. An, L. Huang, Z.P. Li, S.Y. Xu, Y.S. Yuan
IHEP, Beijing, People’s Republic of China

Resonance extraction based on the RCS ring is an important aspect of beam applications. This article proposes a new design of resonance extraction based on the CSNS-RCS ring. By adjusting parameters such as the skew sextupole magnet, beam working point, RF-Kicker, etc., the simulation results from PyOrbit demonstrate the ability to rapidly extract a large number of protons within a few turns.

Slides THAFP02 [1.497 MB]

Poster THAFP02 [0.960 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP02

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Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 01 November 2023

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THAFP03

Measurement of Stability Diagram at IOTA at Fermilab

400

M.K. Bossard, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
R. Ainsworth, N. Eddy
Fermilab, Batavia, Illinois, USA

Funding: Fermilab
Nonlinear focusing elements can enhance the stability of particle beams in high-energy colliders by means of Landau Damping, through the tune spread which is introduced. We propose an experiment at Fermilab’s Integrable Optics Test Accelerator (IOTA) to investigate the influence of nonlinear focusing elements on the transverse stability of the beam. In this experiment, we employ an anti-damper, an active transverse feedback system, as a controlled mechanism to induce coherent beam instability. By utilizing the anti-damper, we can examine the impact of the nonlinear focusing element on the beam’s transverse stability. The stability diagram, a tool used to determine the system’s stability, will be measured using a recently demonstrated method at the LHC. This measurement is carried out experimentally by selecting specific threshold gains and measuring them for a range of phases. The stability diagram is represented by gei¿ on the complex plane. The experiment at IOTA adds insight towards the stability diagram measurement method by supplying a reduced machine impedance, to investigate the impedance’s effect on the stability diagram, as well as a larger range of phase measurements.

Slides THAFP03 [1.331 MB]

Poster THAFP03 [1.692 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP03

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Received ※ 06 October 2023 — Revised ※ 09 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 12 October 2023

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THAFP04

Investigation of Tail-dominated Instability in the Fermilab Recycler Ring

403

O. Mohsen, R. Ainsworth, A.V. Burov
Fermilab, Batavia, Illinois, USA

In our recent operational run, a single bunch, tail-dominated instability was observed in the Fermilab Recycler ring. This instability exclusively occurs in the vertical plane when the chromaticity is close to zero. In this study, we conduct a detailed analysis of this instability under different operational parameters. We investigate the impact of space charge on the head-tail motion and propose potential interpretations of the underlying mechanism of the instability. Moreover, we explore methods to mitigate this instability in the future.

Slides THAFP04 [1.429 MB]

Poster THAFP04 [0.892 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP04

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Received ※ 25 September 2023 — Revised ※ 09 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 29 October 2023

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THAFP05

A Wireless Method for Beam Coupling Impedance Measurements of the LHC Goniometer

407

C. Antuono, C. Zannini
CERN, Meyrin, Switzerland
M. Migliorati, A. Mostacci
LNF-INFN, Frascati, Italy

The beam coupling impedance (BCI) of an accelerator component should be ideally evaluated exciting the device with the beam itself. However, this scenario is not always attainable and alternative methods must be exploited, such as the bench measurements techniques. The stretched Wire Method (WM) is a well established technique for BCI evaluations, although nowadays its limitations are well known. In particular, the stretched wire perturbs the electromagnetic boundary conditions. Therefore, the results obtained could be inaccurate, especially below the cut-off frequency of the beam pipe in the case of cavity-like structures. To overcome these limitations, efforts are being made to investigate alternative bench measurement techniques that will not require the modification of the device under test (DUT). In this framework, a wireless method has been identified and tested for a pillbox cavity. Its potential for more complex structures, such as the LHC crystal goniometer is explored.

Slides THAFP05 [1.088 MB]

Poster THAFP05 [1.151 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP05

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Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 11 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 THBP09 [0.751 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP09

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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 THBP10 [4.059 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP10

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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 THBP11 [1.655 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP11

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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

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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 THBP13 [2.785 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP13

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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 THBP14 [2.632 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP14

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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 THBP15 [0.938 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP15

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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 THBP16 [3.432 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP16

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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

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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

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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 2Q_y=9 in order to avoid emittance blow-up from resonances at Q_x,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 THBP19 [3.077 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP19

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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

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Received ※ 01 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 23 October 2023

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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 THBP21 [1.286 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP21

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Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 31 October 2023

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THBP22

On Liouvillian High Power Beam Accumulation

511

J.-M. Lagniel
GANIL, Caen, France
M.E. Eshraqi, N. Milas
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 THBP22 [2.126 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP22

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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 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

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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 THBP24 [3.231 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP24

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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 THBP27 [4.163 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP27

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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 THBP28 [0.798 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP28

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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 THBP29 [3.711 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP29

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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 THBP30 [1.476 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP30

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Received ※ 19 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 27 October 2023

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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

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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 THBP32 [0.266 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP32

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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 THBP34 [0.840 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP34

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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 THBP35 [0.514 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP35

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Received ※ 28 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 11 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 THBP37 [5.606 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP37

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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

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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 THBP39 [0.861 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP39

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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 THBP40 [0.461 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP40

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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 THBP42 [1.710 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP42

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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 THBP43 [1.345 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP43

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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 THBP44 [1.020 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP44

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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

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Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 15 October 2023

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FRA1I3

EIC cooling

V. Litvinenko
BNL, Upton, New York, USA

Future Electron-Ion Collider (EIC) at BNL would rely on strong cooling of ion and protons beams to reach its design luminosity. In this talk I will discuss number of options for cooling hadron beams in EIC. Main challenge for EIC cooling is to provide cooling of intense proton beam with sufficient cooling decrement and sufficient margins for errors. I will focus on capabilities as well as on challenges of various cooling techniques to fit this challenge.

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FRA2I1

Summary of the Working Group A: Beam Dynamics in Rings

662

H. Bartosik, G. Rumolo
CERN, Meyrin, Switzerland
J.-L. Vay
LBNL, Berkeley, California, USA
N. Wang
IHEP, Beijing, People’s Republic of China

The HB-2023 workshop at CERN from October 9 to 13, 2023 is the continuation of the series of workshops, which started in 2002 at FNAL and rotates every two years between America, Europe and Asia. This contribution summarises the main highlights from Working Group A, Beam Dynamics in Rings, in terms of progress and challenges in the achievement of ever higher intensity and brightness hadron beams in accelerator rings around the world.

Slides FRA2I1 [4.325 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-FRA2I1

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Received ※ 04 December 2023 — Accepted ※ 05 December 2023 — Issued ※ 01 January 2024

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