IPAC2022 - List of Keywords (scattering)

Paper	Title	Other Keywords	Page
MOIYSP2	Touschek and Intrabeam Scattering in Ultralow Emittance Storage Rings	emittance, damping, wiggler, lattice	25
	R. Bartolini DESY, Hamburg, Germany
	In next-generation synchrotron radiation sources targeting extremely low emittance around the so-called diffraction limit, the Touschek and intrabeam scattering (IBS) effects are important factors determining the performance of the facility. As the emittance decreases, the bunch volume decreases and the Touschek beam lifetime also decreases. However, this downward trend in beam lifetime is expected to turn to increase in the emittance region below a certain threshold. Since this threshold is determined by the emittance at equilibrium including the IBS effect, a self-consistent treatment is necessary for a correct and unified understanding of the beam characteristics. In currently operating facilities, such as MAX-IV, or in next-generation light sources under construction or in the planning stages, it is expected that such effects may be observed depending on the operating conditions. This talk will be reviewing Touschek and IBS Effects in terms of how these effects limit the ring performance.
	Slides MOIYSP2 [5.466 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOIYSP2
About •	Received ※ 12 June 2022 — Revised ※ 21 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 27 June 2022
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MOPOST056	Interplay between Space Charge and Intra-beam Scattering for the CERN Ion Injectors	simulation, resonance, space-charge, emittance	214
	M. Zampetakis, F. Antoniou, F. Asvesta, H. Bartosik, Y. Papaphilippou CERN, Meyrin, Switzerland
	The CERN ion injectors, SPS and LEIR, operate in a strong space charge and intra-beam scattering regime, which can lead to degradation of their beam performance. To optimize machine performance requires thus to study the interplay of these two effects in combined space charge and intrabeam scattering tracking simulations. In this respect, the kinetic theory approach of intra-beam scattering has been implemented in pyORBIT and benchmarked against analytical models. First results of combined space charge and intra-beam scattering simulations for SPS and LEIR are presented in this contribution. The simulation results are compared with observations from beam measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST056
About •	Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 07 July 2022
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MOPOST057	Characterization of the Vertical Beam Tails in the CERN PS Booster	resonance, injection, emittance, space-charge	218
	T. Prebibaj, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, G.P. Di Giovanni, E. Renner CERN, Meyrin, Switzerland
	The CERN Proton Synchrotron Booster (PSB) went through major upgrades in the framework of the LHC Injectors Upgrade Project (LIU) aiming to double the brightness of the LHC beams. Operation restarted in early 2021, demonstrating the expected performance improvement. The high-brightness beams, nevertheless, appear to have overpopulated tails in the vertical beam profiles, both at injection and at extraction energies. In an attempt to understand the origin and evolution of the observed tails, systematic profile measurements were performed for different machine and beam configurations using Wire Scanners (WS). The results are presented in this report and compared to simulations. The effect of the Coulomb scattering of the wire to the beam distribution is also addressed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST057
About •	Received ※ 03 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 24 June 2022
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MOPOTK014	Optics of a Recirculating Beamline for MESA	experiment, target, optics, injection	465
	C.P. Stoll, A. Meseck KPH, Mainz, Germany
	The Mainz Energy-recovering Superconducting Accelerator (MESA) is an Energy Recovery Linac (ERL) facility under construction at the Johannes Gutenberg-University in Mainz. It provides the opportunity for precision physics experiments with a 1 mA c.w. electron beam in its initial phase. In this phase experiments with unpolarised, high-density 10¹⁹ atoms per cm² gas jet targets are foreseen at the Mainz Gas Internal Target Experiment (MAGIX). To allow experiments with thin polarised gas targets with sufficiently high interaction rates in a later phase, the beam current must be increased to up to 100 mA, which would pose significant challenges to the existing ERL machine. Thus, it is proposed here to use MESA in pulsed operation with a repetition rate of several kHz to fill a recirculating beamline, providing a quasi c.w. beam current to a thin gas target. The optics necessary for this recirculating beamline are presented here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK014
About •	Received ※ 01 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 07 July 2022
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MOPOMS039	Study of Material Choice in Beam Dumps for Energetic Electron Beams	electron, target, linac, neutron	721
	D. Zhu, R.T. Dowd, Y.E. Tan AS - ANSTO, Clayton, Australia
	Lead is typically used as the initial target in a design for beam dumps for high energy electron beams (>20 MeV). Electron beams with energies above 20 MeV are usually built within concrete bunkers and therefore the design of any beam dump would just be a lead block (very cost effective) as close to the electron source as possible, after a vacuum flange of some sort. In a study of a hypothetical 100 MeV electron beam inside a concrete bunker with an extremely low dose rate constraint outside the bunker, the thickness of lead required would have been too restrictive for a compact design. In this study we investigate the potential benefits of designs that incorpo-rate low Z materials like graphite as the primary target material in vacuum followed by progressively higher Z materials up to lead. The results show the more diffuse elastic scattering from the primary target reduces the back scattered photons and reduces the overall neutron genera-tion. The effect was a more compact design for the beam dump to meet the same dose rate constraint.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS039
About •	Received ※ 08 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 19 June 2022
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TUOXGD1	Design and Construction of Optical System of the Coronagraph for Beam Halo Observation in the SuperKEKB	radiation, synchrotron, synchrotron-radiation, electron	769
	G. Mitsuka, H. Ikeda, T.M. Mitsuhashi KEK, Ibaraki, Japan
	For the observation of beam halo, the coronagraph is designed and constructed in the SuperKEKB. The coronagraph has three stages of optical systems, objective system, re-diffraction system and relay system. Since the SR monitor of SuperKEKB has a long optical path (60 m), we need an objective system with long focal length. The Aperture limit is determined by the diamond mirror which is set in 23.6 m from the source point. Therefore, we must assign this aperture for the entrance pupil of the objective system. For satisfying these conditions, we design a reflective telephoto system based on the Gregorian telescope for the objective system. The focal length is designed to 7028 mm. and front principal point position is designed to the position of diamond mirror. The result of construction, the performance of the objective system has a diffraction limited quality. The re-diffraction system and relay system are also designed based on Kepler type telescope. The result of optical testing using the beam in the HER, we achieved a contrast of 6 order magnitude. Some early result for the observation of beam halo in the HER will also present in this presentation.
	Slides TUOXGD1 [4.345 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXGD1
About •	Received ※ 09 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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TUPOPT050	Investigation of Polarization Dependent Thomson Scattering in an Energy-Recovering Linear Accelerator on the Example of Mesa	electron, photon, HOM, polarization	1114
	C.L. Lorey, A. Meseck KPH, Mainz, Germany
	Funding: GRK 2128 AccelencE funded by the DFG At the Johannes Gutenberg University (JGU) in Mainz, a new accelerator is currently under construction in order to deliver electron beams of up to 155 MeV to two experiments. The Mainz Energy-recovering Superconducting Accelerator (MESA) will offer two modes of operation, one of which is an energy-recovering (ER) mode. As an ERL, MESA, with it’s high brightness electron beam, is a promising accelerator for supplying a Thomson back scattering based Gamma source. Furthermore, at MESA, the polarization of the electron beam can be set by the injector. The aim of this work is to provide a concept and comprehensive analysis of the merit and practical feasibility of a Thomson backscattering source at MESA under consideration of beam polarization and transversal effects. In this paper, an overview and results of our semi analytical approach to calculate various Thomson back scattering light source scenarios at MESA will be given. Furthermore we will discuss the benefits of using polarized electrons in combination with a polarized laser beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT050
About •	Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 26 June 2022
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TUPOPT052	Proposal for Non-Destructive Electron Beam Diagnostic with Laser-Compton Backscattering at the S-Dalinac	photon, electron, laser, linac	1121
	M.G. Meier, M. Arnold, J. Enders, N. Pietralla TU Darmstadt, Darmstadt, Germany
	Funding: Work supported in part by the state of Hesse within the research cluster ELEMENTS (project ID 500/10.006) and the LOEWE research cluster Nuclear Photonics and by DFG through GRK 2128 "Accelence" and Inst163/308-1 FUGG. To recover a large fraction of energy from the accelerator process in an energy-recovery linac, experiments, secondary-beam production, and beam diagnostics must be non-destructive and/or, hence, feature a low interaction probability with the very intense electron-beam. Laser-Compton backscattering can provide a quasi-monochromatic highly polarized X-ray to γ-ray beam without strongly affecting the electron beam due to the small recoil and the small Compton cross-section. Highest energies of the scattered photons are obtained for photon-scattering angles of \ang{180}, i. e., backscattering. A project at TU Darmstadt foresees to synchronize a highly repetitive high-power laser with the Superconducting DArmstadt electron LINear ACcelerator S\hbox{-}DALINAC, capable of running in energy recovery mode * to realize a laser-Compton backscattering source with photon beam energy up to §I{180}{\kilo\electronvolt}. The source will be first used as a diagnostic tool for determining and monitoring key electron-parameters, in particular energy and the energy spread at the S\hbox{-}DALINAC operation. Results are foreseen to be used for optimizing the design of laser-Compton backscattering sources at energy-recovery linacs. *M. Arnold et al., Phys. Rev. Accel. Beams 23, 020101(2020)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT052
About •	Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 24 June 2022
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TUPOMS032	Performance of the Diamond-II Storage Ring Collimators	injection, storage-ring, lattice, collimation	1487
	H. Ghasem, J. Kallestrup, I.P.S. Martin DLS, Oxfordshire, United Kingdom
	Particle losses in a storage ring are unavoidable and it is very important to capture them and protect the machine from any possible damage. For this purpose, 6 collimators have been introduced in the Diamond-II storage ring lattice. This paper describes the main layout of the collimators with their corresponding impact and performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS032
About •	Received ※ 06 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 19 June 2022
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WEOYGD1	Recent Results of Beam Loss Mitigation and Extremely Low Beam Loss Operation of J-PARC RCS	injection, operation, radiation, proton	1616
	P.K. Saha, H. Harada, T. Nakanoya, K. Okabe, H. Okita, Y. Shobuda, F. Tamura, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan H. Hotchi KEK, Tokai, Ibaraki, Japan
	In the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex), multi-turn charge-exchange injection of H⁻ by using a thin stripper foil is performed to achieve high-intensity proton beam of 1 MW. The beam loss at 1 MW has already been well controlled, but for further minimizing both uncontrolled and controlled beam losses caused by the foil scattering of the circulating beam, recently we have implemented a lower vertical injection beam size and installed a corresponding smaller size stripper foil. A smaller foil gives a significant reduction of the foil scattering uncontrolled beam loss at the injection area, while an optimization of the vertical transverse painting area matching with a smaller beam size further gives an extremely reduction of the beam loss at the collimator section. The corresponding residual radiation at the recent operation with 700 kW beam power was also measured to extremely reduced.
	Slides WEOYGD1 [1.161 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOYGD1
About •	Received ※ 20 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 24 June 2022
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WEPOST010	Controlling e⁺/e⁻ Circular Collider Bunch Intensity by Laser Compton Scattering	laser, electron, collider, photon	1695
	F. Zimmermann CERN, Meyrin, Switzerland T.O. Raubenheimer SLAC, Menlo Park, California, USA
	Funding: This project receives funding from the European Union’s H2020 Framework Programme under grant agreement no. 951754 (FCCIS). In the future circular electron-positron collider "FCC-ee", the intensity of colliding bunches must be tightly controlled, with a maximum charge imbalance between collision partner bunches of less than 3-5%. Laser Compton back scattering could be used to adjust and fine-tune the bunch intensity. We discuss a possible implementation and suitable laser parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST010
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 03 July 2022
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WEPOST040	Comparing Methods of Recovering Gamma Energy Distributions from PEDRO Spectrometer Responses	photon, electron, positron, site	1784
	M.H. Oruganti, B. Naranjo, J.B. Rosenzweig, M. Yadav UCLA, Los Angeles, California, USA
	To calculate the energy levels of the photons emitted from high-energy particle interactions, the new pair spectrometer (PEDRO) channels the photons through several Beryllium nuclear fields to produce electron-positron pairs through the nuclear field interaction. This project compared several methods of reconstruction and determined which best predicts original energy distributions based on simulated spectra. These methods included using Maximum Likelihood Estimation, Machine Learning, and directly analyzing a response matrix that modeled PEDRO’s response to any photon energy distribution. We report that performing the direct analysis, also known as QR decomposition, on a PEDRO-generated spectrum provides by far the most accurate calculation of the spectrum’s original energy distribution. These methods were tested against results from experimental cases, including Nonlinear Compton Scattering and Filamentation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST040
About •	Received ※ 15 June 2022 — Revised ※ 01 July 2022 — Accepted ※ 08 July 2022 — Issue date ※ 08 July 2022
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WEPOTK055	Beam Lifetime Measurements in Sirius Storage Ring	vacuum, storage-ring, simulation, synchrotron	2186
	M.B. Alves, L. Liu, X.R. Resende, F.H. de Sá LNLS, Campinas, Brazil
	SIRIUS is the new storage ring-based 4th generation synchrotron light source built and operated by the Brazilian Synchrotron Light Laboratory (LNLS) at the Brazilian Center for Research in Energy and Materials (CNPEM). In ultralow emittance storage rings such as SIRIUS, the dominant contribution to the beam lifetime is due to large angle scattering between electrons within the same bunch, namely the Touschek effect. We used the strategy of storing two bunches simultaneously with different currents to measure their Touschek lifetime independently of other contributions, such as gas scattering. The measurements were carried out in different conditions of bunch current and RF voltage to compare the experimental results with those expected from theory and simulations for SIRIUS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK055
About •	Received ※ 08 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 24 June 2022
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WEPOTK063	A Wireless Method to Obtain the Impedance From Scattering Parameters	impedance, coupling, simulation, GUI	2213
	C. Antuono, M. Migliorati, E. Métral, C. Zannini CERN, Meyrin, Switzerland M. Migliorati, A. Mostacci LNF-INFN, Frascati, Italy A. Mostacci Sapienza University of Rome, Rome, Italy
	The coaxial wire method is a common and appreciated choice to assess the beam coupling impedance of an accelerator element from scattering parameters. Nevertheless, the results obtained from wire measurements could be inaccurate due to the presence of the stretched conductive wire that artificially creates the conditions for the propagation of a Transverse ElectroMagnetic (TEM) mode. The aim of this work is to establish a solid technique to obtain the beam coupling impedance from electromagnetic simulations, without modifications of the device under test. In this framework, we identified a new relation to get the resistive wall beam coupling impedance of a circular chamber directly from the scattering parameters and demonstrated that it reduces to the exact theoretical expression. Furthermore, a possible generalization of the method to arbitrary cross section geometries has been studied and validated with numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK063
About •	Received ※ 07 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 20 June 2022
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WEPOTK065	Revisiting Intrabeam Scattering for Laminar Beams	space-charge, electron, simulation, emittance	2221
	R. Robles, Z. Huang, A. Marinelli SLAC, Menlo Park, California, USA
	Funding: This work was supported by US Department of Energy Contracts No. DE-AC02-76SF00515 Intrabeam scattering (IBS) is becoming an increasingly important effect in the design of high-brightness linear electron accelerators due to the ever-increasing transverse brightness of beams produced from radiofrequency photoinjectors. The existing theory describing the energy spread growth rate due to IBS was derived in the context of circular machines where the beam particles are frequently and randomly colliding, and therefore should only be applied to non-laminar, emittance dominated flow. This is not the case in the injector portion of a linear accelerator, where the beam is space-charge dominated and the flow is laminar. The different nature of the microscopic motion in the two cases demands a reevaluation of the applicability of IBS theory to the photoinjector. In this work, we present a simple analytic model for energy spread growth during perfectly laminar flow and show that it matches well to point-to-point multiparticle simulations. In this way we demonstrate that stochastic energy spread growth in laminar beams is more attributable to the initial random placement of the particles in the bunch rather than the traditional temperature rearrangement mechanism of IBS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK065
About •	Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 08 July 2022
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THPOPT023	Flexible Features of the Compact Storage Ring in the cSTART Project at Karlsruhe Institute of Technology	electron, storage-ring, lattice, sextupole	2620
	A.I. Papash, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A.-S. Müller, R. Ruprecht, J. Schäfer, M. Schwarz KIT, Karlsruhe, Germany
	Within the cSTART project (compact storage ring for accelerator research and technology), a Very Large Acceptance compact Storage Ring (VLA-cSR) will be realized at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology. (KIT). A modified geometry of a compact storage ring operating at 50 MeV energy range has been studied and main features of the new model are described here. The new design, based on 45° bending magnets, is suitable to store a wide momentum spread beam as well as ultra-short electron bunches in the sub-ps range injected from the plasma cell as well as from the Ferninfrarot Linac- Und Test Experiment (FLUTE). The DBA lattice of the VLA-cSR with different settings and relaxed parameters, split elements and higher order optics of tolerable strength allows to improve the dynamic aperture and momentum acceptance to an acceptable level. This contribution discusses the lattice features in detail, expected lifetime, injection, tolerances and different possible operation schemes of the ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT023
About •	Received ※ 20 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 02 July 2022
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THPOMS003	Upgrade of a Proton Therapy Eye Treatment Nozzle Using a Cylindrical Beam Stopping Device for Enhanced Dose Rate Performances	proton, simulation, radiation, ECR	2937
	E. Gnacadja, C. Hernalsteens, N. Pauly, E. Ramoisiaux, R. Tesse, M. Vanwelde ULB, Bruxelles, Belgium C. Hernalsteens CERN, Meyrin, Switzerland
	Proton therapy is a well established treatment method for ocular cancerous diseases. General-purpose multi-room systems which comprise eye-treatment beamlines must be thoroughly optimized to achieve the performances of fully dedicated systems in terms of depth-dose distal fall-off, lateral penumbra, and dose rate. For eye-treatment beamlines, the dose rate is one of the most critical clinical performances, as it directly defines the delivery time of a given treatment session. This delivery time must be kept as low as possible to reduce uncertainties due to undesired patient movement. We propose an alternative design of the Ion Beam Applications (IBA) Proteus Plus (P+) eye treatment beamline, which combines a beam-stopping device with the already existing scattering features of the beamline. The design is modelled with Beam Delivery SIMulation (BDSIM), a Geant4-based particle tracking and beam-matter interactions Monte-Carlo code, to demonstrate that it increases the maximum achievable dose rate by up to a factor §I{3} compared to the baseline configuration. An in-depth study of the system is performed and the resulting dosimetric properties are discussed in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS003
About •	Received ※ 20 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 26 June 2022
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THPOMS010	Heating and Beam Impact of High Intensity Exit Windows for FLASHlab@PITZ	electron, radiation, Windows, simulation	2958
	Z. Amirkhanyan CANDLE SRI, Yerevan, Armenia Z. Aboulbanine, M. Groß, M. Krasilnikov, T. Kuhl, X.-K. Li, R. Niemczyk, A. Oppelt, S. Philipp, H.J. Qian, F. Stephan DESY Zeuthen, Zeuthen, Germany M. Schmitz DESY, Hamburg, Germany
	The high-brightness electron beam at the Photo Injector Test facility at DESY in Zeuthen (PITZ) is being prepared for use in dosimetry experiments and for the study of biological effects in thin samples. This is part of the preparations for FLASHlab@PITZ which is going to be an R&D platform for FLASH and VHEE radiation therapy and radiation biology. These studies require precise information on the electron beam parameters downstream of the exit window, such as the scattering angle and the energy spectrum of the particles as well as the thermal load on the exit window. A Titanium window is compared with a DESY Graphite window design. Heat deposition in the window by a single 22MeV / 1nC electron bunch of various size, its scattering and energy spectrum due to passage through the window are calculated by means of the Monte Carlo program FLUKA. Time resolved temperature profiles, as generated by the passage of 1ms long electron pulse trains with up to 4500 single pulses, each of them between 0.1 and 60ps long, are calculated with a self-written FEM code.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS010
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 30 June 2022
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THPOMS020	Beam Optics Study for a Potential VHEE Beam Delivery System	electron, optics, quadrupole, dipole	2992
	C.S. Robertson, P. Burrows JAI, Oxford, United Kingdom M. Dosanjh, A. Gerbershagen, A. Latina CERN, Meyrin, Switzerland
	VHEE (Very High Energy Electron) therapy can be superior to conventional radiotherapy for the treatment of deep seated tumours, whilst not necessarily requiring the space and cost of proton or heavy ion facilities. Developments in high gradient RF technology have allowed electrons to be accelerated to VHEE energies in a compact space, meaning that treatment could be possible with a shorter linac. A crucial component of VHEE treatment is the transfer of the beam from accelerator to patient. This is required to magnify the beam to cover the transverse extent of the tumour, whilst ensuring a uniform beam distribution. Two principle methodologies for the design of a compact transfer line are presented. The first of these is based upon a quadrupole lattice and optical magnification of beam size. A minimisation algorithm is used to enforce certain criteria on the beam distribution at the patient, defining the lattice through an automated routine. Separately, a dual scattering-foil based system is also presented, which uses similar algorithms for the optimisation of the foil geometry in order to achieve the desired beam shape at the patient location.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS020
About •	Received ※ 19 May 2022 — Accepted ※ 16 June 2022 — Issue date ※ 18 June 2022
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THPOMS025	A Novel Method of Emittance Matching to Increase Beam Transmission for Cyclotron Based Proton Therapy Facilities: Simulation Study	emittance, optics, proton, cyclotron	3007
	V. Maradia, A.L. Lomax, D. Meer, S. Psoroulas, J.M. Schippers, D.C. Weber PSI, Villigen PSI, Switzerland V. Maradia ETH, Zurich, Switzerland
	Funding: This work is supported by a PSI inter-departmental funding initiative (Cross) In proton therapy, high dose rates can reduce treatment delivery times, allowing for efficient mitigation of tumor motion and increased patient throughput. With cyclotrons, however, high dose rates are difficult to achieve for low-energies as, typically, the emittance after the degrader is matched in both transversal planes using circular collimators, which does not provide an optimal matching to the acceptance of the following beamline. Transmission can however be substantially improved by transporting maximum acceptable emittances in both orthogonal planes, but at the cost of gantry angle-dependent beam shapes at isocenter. Here we demonstrate that equal emittances in both planes can be recovered at the gantry entrance using a thin scattering foil, thus ensuring gantry angle-independent beam shapes at the isocenter. We demonstrate experimentally that low-energy beam transmission can be increased by a factor of 3 using this approach compared to the currently used beam optics, whilst gantry angle-independent beam shapes are preserved. We expect that this universal approach could also bring a similar transmission improvement in other cyclotron-based proton therapy facilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS025
About •	Received ※ 16 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 28 June 2022 — Issue date ※ 28 June 2022
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Paper

Title

Other Keywords

Page

MOIYSP2

Touschek and Intrabeam Scattering in Ultralow Emittance Storage Rings

emittance, damping, wiggler, lattice

25

R. Bartolini
DESY, Hamburg, Germany

In next-generation synchrotron radiation sources targeting extremely low emittance around the so-called diffraction limit, the Touschek and intrabeam scattering (IBS) effects are important factors determining the performance of the facility. As the emittance decreases, the bunch volume decreases and the Touschek beam lifetime also decreases. However, this downward trend in beam lifetime is expected to turn to increase in the emittance region below a certain threshold. Since this threshold is determined by the emittance at equilibrium including the IBS effect, a self-consistent treatment is necessary for a correct and unified understanding of the beam characteristics. In currently operating facilities, such as MAX-IV, or in next-generation light sources under construction or in the planning stages, it is expected that such effects may be observed depending on the operating conditions. This talk will be reviewing Touschek and IBS Effects in terms of how these effects limit the ring performance.

Slides MOIYSP2 [5.466 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOIYSP2

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Received ※ 12 June 2022 — Revised ※ 21 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 27 June 2022

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MOPOST056

Interplay between Space Charge and Intra-beam Scattering for the CERN Ion Injectors

simulation, resonance, space-charge, emittance

214

M. Zampetakis, F. Antoniou, F. Asvesta, H. Bartosik, Y. Papaphilippou
CERN, Meyrin, Switzerland

The CERN ion injectors, SPS and LEIR, operate in a strong space charge and intra-beam scattering regime, which can lead to degradation of their beam performance. To optimize machine performance requires thus to study the interplay of these two effects in combined space charge and intrabeam scattering tracking simulations. In this respect, the kinetic theory approach of intra-beam scattering has been implemented in pyORBIT and benchmarked against analytical models. First results of combined space charge and intra-beam scattering simulations for SPS and LEIR are presented in this contribution. The simulation results are compared with observations from beam measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST056

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Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 07 July 2022

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MOPOST057

Characterization of the Vertical Beam Tails in the CERN PS Booster

resonance, injection, emittance, space-charge

218

T. Prebibaj, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, G.P. Di Giovanni, E. Renner
CERN, Meyrin, Switzerland

The CERN Proton Synchrotron Booster (PSB) went through major upgrades in the framework of the LHC Injectors Upgrade Project (LIU) aiming to double the brightness of the LHC beams. Operation restarted in early 2021, demonstrating the expected performance improvement. The high-brightness beams, nevertheless, appear to have overpopulated tails in the vertical beam profiles, both at injection and at extraction energies. In an attempt to understand the origin and evolution of the observed tails, systematic profile measurements were performed for different machine and beam configurations using Wire Scanners (WS). The results are presented in this report and compared to simulations. The effect of the Coulomb scattering of the wire to the beam distribution is also addressed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST057

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Received ※ 03 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 24 June 2022

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MOPOTK014

Optics of a Recirculating Beamline for MESA

experiment, target, optics, injection

465

C.P. Stoll, A. Meseck
KPH, Mainz, Germany

The Mainz Energy-recovering Superconducting Accelerator (MESA) is an Energy Recovery Linac (ERL) facility under construction at the Johannes Gutenberg-University in Mainz. It provides the opportunity for precision physics experiments with a 1 mA c.w. electron beam in its initial phase. In this phase experiments with unpolarised, high-density 10¹⁹ atoms per cm² gas jet targets are foreseen at the Mainz Gas Internal Target Experiment (MAGIX). To allow experiments with thin polarised gas targets with sufficiently high interaction rates in a later phase, the beam current must be increased to up to 100 mA, which would pose significant challenges to the existing ERL machine. Thus, it is proposed here to use MESA in pulsed operation with a repetition rate of several kHz to fill a recirculating beamline, providing a quasi c.w. beam current to a thin gas target. The optics necessary for this recirculating beamline are presented here.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK014

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Received ※ 01 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 07 July 2022

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MOPOMS039

Study of Material Choice in Beam Dumps for Energetic Electron Beams

electron, target, linac, neutron

721

D. Zhu, R.T. Dowd, Y.E. Tan
AS - ANSTO, Clayton, Australia

Lead is typically used as the initial target in a design for beam dumps for high energy electron beams (>20 MeV). Electron beams with energies above 20 MeV are usually built within concrete bunkers and therefore the design of any beam dump would just be a lead block (very cost effective) as close to the electron source as possible, after a vacuum flange of some sort. In a study of a hypothetical 100 MeV electron beam inside a concrete bunker with an extremely low dose rate constraint outside the bunker, the thickness of lead required would have been too restrictive for a compact design. In this study we investigate the potential benefits of designs that incorpo-rate low Z materials like graphite as the primary target material in vacuum followed by progressively higher Z materials up to lead. The results show the more diffuse elastic scattering from the primary target reduces the back scattered photons and reduces the overall neutron genera-tion. The effect was a more compact design for the beam dump to meet the same dose rate constraint.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS039

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Received ※ 08 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 19 June 2022

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TUOXGD1

Design and Construction of Optical System of the Coronagraph for Beam Halo Observation in the SuperKEKB

radiation, synchrotron, synchrotron-radiation, electron

769

G. Mitsuka, H. Ikeda, T.M. Mitsuhashi
KEK, Ibaraki, Japan

For the observation of beam halo, the coronagraph is designed and constructed in the SuperKEKB. The coronagraph has three stages of optical systems, objective system, re-diffraction system and relay system. Since the SR monitor of SuperKEKB has a long optical path (60 m), we need an objective system with long focal length. The Aperture limit is determined by the diamond mirror which is set in 23.6 m from the source point. Therefore, we must assign this aperture for the entrance pupil of the objective system. For satisfying these conditions, we design a reflective telephoto system based on the Gregorian telescope for the objective system. The focal length is designed to 7028 mm. and front principal point position is designed to the position of diamond mirror. The result of construction, the performance of the objective system has a diffraction limited quality. The re-diffraction system and relay system are also designed based on Kepler type telescope. The result of optical testing using the beam in the HER, we achieved a contrast of 6 order magnitude. Some early result for the observation of beam halo in the HER will also present in this presentation.

Slides TUOXGD1 [4.345 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXGD1

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Received ※ 09 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022

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TUPOPT050

Investigation of Polarization Dependent Thomson Scattering in an Energy-Recovering Linear Accelerator on the Example of Mesa

electron, photon, HOM, polarization

1114

C.L. Lorey, A. Meseck
KPH, Mainz, Germany

Funding: GRK 2128 AccelencE funded by the DFG
At the Johannes Gutenberg University (JGU) in Mainz, a new accelerator is currently under construction in order to deliver electron beams of up to 155 MeV to two experiments. The Mainz Energy-recovering Superconducting Accelerator (MESA) will offer two modes of operation, one of which is an energy-recovering (ER) mode. As an ERL, MESA, with it’s high brightness electron beam, is a promising accelerator for supplying a Thomson back scattering based Gamma source. Furthermore, at MESA, the polarization of the electron beam can be set by the injector. The aim of this work is to provide a concept and comprehensive analysis of the merit and practical feasibility of a Thomson backscattering source at MESA under consideration of beam polarization and transversal effects. In this paper, an overview and results of our semi analytical approach to calculate various Thomson back scattering light source scenarios at MESA will be given. Furthermore we will discuss the benefits of using polarized electrons in combination with a polarized laser beam.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT050

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Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 26 June 2022

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TUPOPT052

Proposal for Non-Destructive Electron Beam Diagnostic with Laser-Compton Backscattering at the S-Dalinac

photon, electron, laser, linac

1121

M.G. Meier, M. Arnold, J. Enders, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: Work supported in part by the state of Hesse within the research cluster ELEMENTS (project ID 500/10.006) and the LOEWE research cluster Nuclear Photonics and by DFG through GRK 2128 "Accelence" and Inst163/308-1 FUGG.
To recover a large fraction of energy from the accelerator process in an energy-recovery linac, experiments, secondary-beam production, and beam diagnostics must be non-destructive and/or, hence, feature a low interaction probability with the very intense electron-beam. Laser-Compton backscattering can provide a quasi-monochromatic highly polarized X-ray to γ-ray beam without strongly affecting the electron beam due to the small recoil and the small Compton cross-section. Highest energies of the scattered photons are obtained for photon-scattering angles of \ang{180}, i. e., backscattering. A project at TU Darmstadt foresees to synchronize a highly repetitive high-power laser with the Superconducting DArmstadt electron LINear ACcelerator S\hbox{-}DALINAC, capable of running in energy recovery mode * to realize a laser-Compton backscattering source with photon beam energy up to §I{180}{\kilo\electronvolt}. The source will be first used as a diagnostic tool for determining and monitoring key electron-parameters, in particular energy and the energy spread at the S\hbox{-}DALINAC operation. Results are foreseen to be used for optimizing the design of laser-Compton backscattering sources at energy-recovery linacs.
*M. Arnold et al., Phys. Rev. Accel. Beams 23, 020101(2020)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT052

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Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 24 June 2022

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TUPOMS032

Performance of the Diamond-II Storage Ring Collimators

injection, storage-ring, lattice, collimation

1487

H. Ghasem, J. Kallestrup, I.P.S. Martin
DLS, Oxfordshire, United Kingdom

Particle losses in a storage ring are unavoidable and it is very important to capture them and protect the machine from any possible damage. For this purpose, 6 collimators have been introduced in the Diamond-II storage ring lattice. This paper describes the main layout of the collimators with their corresponding impact and performance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS032

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Received ※ 06 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 19 June 2022

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WEOYGD1

Recent Results of Beam Loss Mitigation and Extremely Low Beam Loss Operation of J-PARC RCS

injection, operation, radiation, proton

1616

P.K. Saha, H. Harada, T. Nakanoya, K. Okabe, H. Okita, Y. Shobuda, F. Tamura, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
H. Hotchi
KEK, Tokai, Ibaraki, Japan

In the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex), multi-turn charge-exchange injection of H⁻ by using a thin stripper foil is performed to achieve high-intensity proton beam of 1 MW. The beam loss at 1 MW has already been well controlled, but for further minimizing both uncontrolled and controlled beam losses caused by the foil scattering of the circulating beam, recently we have implemented a lower vertical injection beam size and installed a corresponding smaller size stripper foil. A smaller foil gives a significant reduction of the foil scattering uncontrolled beam loss at the injection area, while an optimization of the vertical transverse painting area matching with a smaller beam size further gives an extremely reduction of the beam loss at the collimator section. The corresponding residual radiation at the recent operation with 700 kW beam power was also measured to extremely reduced.

Slides WEOYGD1 [1.161 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOYGD1

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Received ※ 20 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 24 June 2022

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WEPOST010

Controlling e⁺/e⁻ Circular Collider Bunch Intensity by Laser Compton Scattering

laser, electron, collider, photon

1695

F. Zimmermann
CERN, Meyrin, Switzerland
T.O. Raubenheimer
SLAC, Menlo Park, California, USA

Funding: This project receives funding from the European Union’s H2020 Framework Programme under grant agreement no. 951754 (FCCIS).
In the future circular electron-positron collider "FCC-ee", the intensity of colliding bunches must be tightly controlled, with a maximum charge imbalance between collision partner bunches of less than 3-5%. Laser Compton back scattering could be used to adjust and fine-tune the bunch intensity. We discuss a possible implementation and suitable laser parameters.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST010

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 03 July 2022

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WEPOST040

Comparing Methods of Recovering Gamma Energy Distributions from PEDRO Spectrometer Responses

photon, electron, positron, site

1784

M.H. Oruganti, B. Naranjo, J.B. Rosenzweig, M. Yadav
UCLA, Los Angeles, California, USA

To calculate the energy levels of the photons emitted from high-energy particle interactions, the new pair spectrometer (PEDRO) channels the photons through several Beryllium nuclear fields to produce electron-positron pairs through the nuclear field interaction. This project compared several methods of reconstruction and determined which best predicts original energy distributions based on simulated spectra. These methods included using Maximum Likelihood Estimation, Machine Learning, and directly analyzing a response matrix that modeled PEDRO’s response to any photon energy distribution. We report that performing the direct analysis, also known as QR decomposition, on a PEDRO-generated spectrum provides by far the most accurate calculation of the spectrum’s original energy distribution. These methods were tested against results from experimental cases, including Nonlinear Compton Scattering and Filamentation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST040

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Received ※ 15 June 2022 — Revised ※ 01 July 2022 — Accepted ※ 08 July 2022 — Issue date ※ 08 July 2022

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WEPOTK055

Beam Lifetime Measurements in Sirius Storage Ring

vacuum, storage-ring, simulation, synchrotron

2186

M.B. Alves, L. Liu, X.R. Resende, F.H. de Sá
LNLS, Campinas, Brazil

SIRIUS is the new storage ring-based 4th generation synchrotron light source built and operated by the Brazilian Synchrotron Light Laboratory (LNLS) at the Brazilian Center for Research in Energy and Materials (CNPEM). In ultralow emittance storage rings such as SIRIUS, the dominant contribution to the beam lifetime is due to large angle scattering between electrons within the same bunch, namely the Touschek effect. We used the strategy of storing two bunches simultaneously with different currents to measure their Touschek lifetime independently of other contributions, such as gas scattering. The measurements were carried out in different conditions of bunch current and RF voltage to compare the experimental results with those expected from theory and simulations for SIRIUS.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK055

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Received ※ 08 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 24 June 2022

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WEPOTK063

A Wireless Method to Obtain the Impedance From Scattering Parameters

impedance, coupling, simulation, GUI

2213

C. Antuono, M. Migliorati, E. Métral, C. Zannini
CERN, Meyrin, Switzerland
M. Migliorati, A. Mostacci
LNF-INFN, Frascati, Italy
A. Mostacci
Sapienza University of Rome, Rome, Italy

The coaxial wire method is a common and appreciated choice to assess the beam coupling impedance of an accelerator element from scattering parameters. Nevertheless, the results obtained from wire measurements could be inaccurate due to the presence of the stretched conductive wire that artificially creates the conditions for the propagation of a Transverse ElectroMagnetic (TEM) mode. The aim of this work is to establish a solid technique to obtain the beam coupling impedance from electromagnetic simulations, without modifications of the device under test. In this framework, we identified a new relation to get the resistive wall beam coupling impedance of a circular chamber directly from the scattering parameters and demonstrated that it reduces to the exact theoretical expression. Furthermore, a possible generalization of the method to arbitrary cross section geometries has been studied and validated with numerical simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK063

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Received ※ 07 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 20 June 2022

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WEPOTK065

Revisiting Intrabeam Scattering for Laminar Beams

space-charge, electron, simulation, emittance

2221

R. Robles, Z. Huang, A. Marinelli
SLAC, Menlo Park, California, USA

Funding: This work was supported by US Department of Energy Contracts No. DE-AC02-76SF00515
Intrabeam scattering (IBS) is becoming an increasingly important effect in the design of high-brightness linear electron accelerators due to the ever-increasing transverse brightness of beams produced from radiofrequency photoinjectors. The existing theory describing the energy spread growth rate due to IBS was derived in the context of circular machines where the beam particles are frequently and randomly colliding, and therefore should only be applied to non-laminar, emittance dominated flow. This is not the case in the injector portion of a linear accelerator, where the beam is space-charge dominated and the flow is laminar. The different nature of the microscopic motion in the two cases demands a reevaluation of the applicability of IBS theory to the photoinjector. In this work, we present a simple analytic model for energy spread growth during perfectly laminar flow and show that it matches well to point-to-point multiparticle simulations. In this way we demonstrate that stochastic energy spread growth in laminar beams is more attributable to the initial random placement of the particles in the bunch rather than the traditional temperature rearrangement mechanism of IBS.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK065

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Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 08 July 2022

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THPOPT023

Flexible Features of the Compact Storage Ring in the cSTART Project at Karlsruhe Institute of Technology

electron, storage-ring, lattice, sextupole

2620

A.I. Papash, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A.-S. Müller, R. Ruprecht, J. Schäfer, M. Schwarz
KIT, Karlsruhe, Germany

Within the cSTART project (compact storage ring for accelerator research and technology), a Very Large Acceptance compact Storage Ring (VLA-cSR) will be realized at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology. (KIT). A modified geometry of a compact storage ring operating at 50 MeV energy range has been studied and main features of the new model are described here. The new design, based on 45° bending magnets, is suitable to store a wide momentum spread beam as well as ultra-short electron bunches in the sub-ps range injected from the plasma cell as well as from the Ferninfrarot Linac- Und Test Experiment (FLUTE). The DBA lattice of the VLA-cSR with different settings and relaxed parameters, split elements and higher order optics of tolerable strength allows to improve the dynamic aperture and momentum acceptance to an acceptable level. This contribution discusses the lattice features in detail, expected lifetime, injection, tolerances and different possible operation schemes of the ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT023

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Received ※ 20 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 02 July 2022

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THPOMS003

Upgrade of a Proton Therapy Eye Treatment Nozzle Using a Cylindrical Beam Stopping Device for Enhanced Dose Rate Performances

proton, simulation, radiation, ECR

2937

E. Gnacadja, C. Hernalsteens, N. Pauly, E. Ramoisiaux, R. Tesse, M. Vanwelde
ULB, Bruxelles, Belgium
C. Hernalsteens
CERN, Meyrin, Switzerland

Proton therapy is a well established treatment method for ocular cancerous diseases. General-purpose multi-room systems which comprise eye-treatment beamlines must be thoroughly optimized to achieve the performances of fully dedicated systems in terms of depth-dose distal fall-off, lateral penumbra, and dose rate. For eye-treatment beamlines, the dose rate is one of the most critical clinical performances, as it directly defines the delivery time of a given treatment session. This delivery time must be kept as low as possible to reduce uncertainties due to undesired patient movement. We propose an alternative design of the Ion Beam Applications (IBA) Proteus Plus (P+) eye treatment beamline, which combines a beam-stopping device with the already existing scattering features of the beamline. The design is modelled with Beam Delivery SIMulation (BDSIM), a Geant4-based particle tracking and beam-matter interactions Monte-Carlo code, to demonstrate that it increases the maximum achievable dose rate by up to a factor §I{3} compared to the baseline configuration. An in-depth study of the system is performed and the resulting dosimetric properties are discussed in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS003

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Received ※ 20 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 26 June 2022

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THPOMS010

Heating and Beam Impact of High Intensity Exit Windows for FLASHlab@PITZ

electron, radiation, Windows, simulation

2958

Z. Amirkhanyan
CANDLE SRI, Yerevan, Armenia
Z. Aboulbanine, M. Groß, M. Krasilnikov, T. Kuhl, X.-K. Li, R. Niemczyk, A. Oppelt, S. Philipp, H.J. Qian, F. Stephan
DESY Zeuthen, Zeuthen, Germany
M. Schmitz
DESY, Hamburg, Germany

The high-brightness electron beam at the Photo Injector Test facility at DESY in Zeuthen (PITZ) is being prepared for use in dosimetry experiments and for the study of biological effects in thin samples. This is part of the preparations for FLASHlab@PITZ which is going to be an R&D platform for FLASH and VHEE radiation therapy and radiation biology. These studies require precise information on the electron beam parameters downstream of the exit window, such as the scattering angle and the energy spectrum of the particles as well as the thermal load on the exit window. A Titanium window is compared with a DESY Graphite window design. Heat deposition in the window by a single 22MeV / 1nC electron bunch of various size, its scattering and energy spectrum due to passage through the window are calculated by means of the Monte Carlo program FLUKA. Time resolved temperature profiles, as generated by the passage of 1ms long electron pulse trains with up to 4500 single pulses, each of them between 0.1 and 60ps long, are calculated with a self-written FEM code.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS010

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Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 30 June 2022

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THPOMS020

Beam Optics Study for a Potential VHEE Beam Delivery System

electron, optics, quadrupole, dipole

2992

C.S. Robertson, P. Burrows
JAI, Oxford, United Kingdom
M. Dosanjh, A. Gerbershagen, A. Latina
CERN, Meyrin, Switzerland

VHEE (Very High Energy Electron) therapy can be superior to conventional radiotherapy for the treatment of deep seated tumours, whilst not necessarily requiring the space and cost of proton or heavy ion facilities. Developments in high gradient RF technology have allowed electrons to be accelerated to VHEE energies in a compact space, meaning that treatment could be possible with a shorter linac. A crucial component of VHEE treatment is the transfer of the beam from accelerator to patient. This is required to magnify the beam to cover the transverse extent of the tumour, whilst ensuring a uniform beam distribution. Two principle methodologies for the design of a compact transfer line are presented. The first of these is based upon a quadrupole lattice and optical magnification of beam size. A minimisation algorithm is used to enforce certain criteria on the beam distribution at the patient, defining the lattice through an automated routine. Separately, a dual scattering-foil based system is also presented, which uses similar algorithms for the optimisation of the foil geometry in order to achieve the desired beam shape at the patient location.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS020

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Received ※ 19 May 2022 — Accepted ※ 16 June 2022 — Issue date ※ 18 June 2022

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THPOMS025

A Novel Method of Emittance Matching to Increase Beam Transmission for Cyclotron Based Proton Therapy Facilities: Simulation Study

emittance, optics, proton, cyclotron

3007

V. Maradia, A.L. Lomax, D. Meer, S. Psoroulas, J.M. Schippers, D.C. Weber
PSI, Villigen PSI, Switzerland
V. Maradia
ETH, Zurich, Switzerland

Funding: This work is supported by a PSI inter-departmental funding initiative (Cross)
In proton therapy, high dose rates can reduce treatment delivery times, allowing for efficient mitigation of tumor motion and increased patient throughput. With cyclotrons, however, high dose rates are difficult to achieve for low-energies as, typically, the emittance after the degrader is matched in both transversal planes using circular collimators, which does not provide an optimal matching to the acceptance of the following beamline. Transmission can however be substantially improved by transporting maximum acceptable emittances in both orthogonal planes, but at the cost of gantry angle-dependent beam shapes at isocenter. Here we demonstrate that equal emittances in both planes can be recovered at the gantry entrance using a thin scattering foil, thus ensuring gantry angle-independent beam shapes at the isocenter. We demonstrate experimentally that low-energy beam transmission can be increased by a factor of 3 using this approach compared to the currently used beam optics, whilst gantry angle-independent beam shapes are preserved. We expect that this universal approach could also bring a similar transmission improvement in other cyclotron-based proton therapy facilities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS025

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Received ※ 16 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 28 June 2022 — Issue date ※ 28 June 2022

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