IBIC2023 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MO2I02	Fast Orbit Feedback for Diamond-II	controls, storage-ring, feedback, electron	1
	I. Kempf, M.G. Abbott, L. Bobb, G.B. Christian DLS, Harwell, United Kingdom S. Duncan University of Oxford, Oxford, United Kingdom G. Rehm HZB, Berlin, Germany
	Funding: Diamond Light Source and Engineering and Physical Sciences Research Council The electron beam stability is critical for 4th generation light sources. As opposed to 10% of beam size up to 140 Hz at Diamond, advances in detector speed and resolution at Diamond-II increase the stability requirements to 3% up to 1 kHz. This paper presents a novel control methodology for the fast orbit feedback at Diamond-II, which will stabilise the beam using two arrays of 252 slow and 144 fast correctors and 252 beam position monitors at 100 kHz. In contrast to existing approaches that separate slow and fast feedback loops, our approach is based on a two-matrix factorisation called the generalised singular value decomposition (GSVD), which decouples the system into 144 two-input modes controlled by slow and fast magnets and 108 modes controlled by slow magnets only. The GSVD-based controller is implemented in the existing Diamond storage ring using a centralised communication architecture, such as planned for Diamond-II. We present results from the Diamond storage ring and simulation, which confirm that the proposed approach meets the target specification for Diamond-II.
	Slides MO2I02 [3.686 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO2I02
About •	Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 11 September 2023 — Issue date ※ 18 September 2023
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MOP002	MiniBEE - Minibeam Beamline for Preclinical Experiments	proton, radiation, target, cyclotron	34
	J. Reindl, G. Datzmann, G. Dollinger, J. Neubauer, A. Rousseti Universität der Bundeswehr Muenchen, Neubiberg, Germany J. Bundesmann, A. Denker, A. Dittwald, G. Kourkafas HZB, Berlin, Germany G. Datzmann Datzmann Interact & Innovate GmbH, München, Germany A. Denker BHT, Berlin, Germany
	Spatial fractionated radiotherapy using protons, so-called proton minibeam radiotherapy (pMBT) was developed for better sparing of normal tissue in the entrance channel of radiation. Progressing towards clinical use, pMBT should overcome current technical and biomedical limitations. This work discusses a preclinical pMBT facility, currently built at the 68.5MeV cyclotron at the Helmholtz Zentrum Berlin. The goal is to irradiate small animals using focused pMBT with a σ of 50µm, a high peak-to-valley dose ratio at center-to-center distance as small as 1mm and beam current of 1nA. A first degrader defines the maximum energy of the beam. Dipole magnets and quadrupole triplets transport the beam to the treatment room while multiple slits properly form the transverse beam profiles. A high magnetic field gradient triplet lens forms the minibeams in front of the target station and, scanning magnets are used for a raster scan at the target. An additional degrader, positioned close before the focusing spot and the target, further reduces the energy, forming a spread-out Bragg peak. A small animal radiation research platform will be used for imaging and positioning of the target.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP002
About •	Received ※ 09 September 2023 — Revised ※ 14 September 2023 — Accepted ※ 25 September 2023 — Issue date ※ 29 September 2023
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MOP004	Design and Study of Cavity Quadrupole Moment and Energy Spread Monitor	cavity, quadrupole, framework, linac	37
	Q. Wang, Q.Y. Dong, L.T. Huang DICP, Dalian, Liaoning, People’s Republic of China Q. Luo USTC/NSRL, Hefei, Anhui, People’s Republic of China
	A nondestructive method to measure beam energy spread using the quadrupole modes within a microwave cavity is proposed. Compared with a button beam position monitor (BBPM) or a stripline beam position monitor (SBPM), the cavity monitor is a narrow band pickup and therefore has better signal-to-noise ratio (SNR) and resolution. In this study, a rectangular cavity monitor is designed. TM220 mode operating at 4.76 GHz in the cavity reflects the quadrupole moment of the beam. The cavity plans to be installed behind a bending magnet in Dalian Coherent Light Source (DCLS), an extreme ultraviolet FEL facility. In this position, the beam has a larger dispersion, which is beneficial to measure the energy spread. A quadrupole magnet, a fluorescent screen, and a SBPM with eight electrodes is installed near the cavity for calibration and comparison. The systematic framework and simulation results are also discussed in this paper.
	Poster MOP004 [0.882 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP004
About •	Received ※ 13 July 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 28 September 2023
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MOP010	Diagnostics for a High Emittance and High Energy Spread Positron Source	diagnostics, pick-up, positron, experiment	54
	N. Vallis, P. Craievich, R.F. Fortunati, R. Ischebeck, E. Ismaili, P.N. Juranič, F. Marcellini, G.L. Orlandi, M. Schaer, R. Zennaro, M. Zykova PSI, Villigen PSI, Switzerland
	Funding: This work was done under the auspices of CHART (chart.ch) This paper is an overview of a diagnostics setup for highly spread e⁺e⁻ beams, to be installed at the PSI Positron Production (P³ or P-cubed) experiment. To be hosted at the SwissFEL facility (PSI, Switzerland) in 2026, P³ is e⁺ source demonstrator designed to generate, capture, separate and detect nano-Coulombs of secondary e⁺ and e^- bunches, in spite of their extreme tranverse emittance and energy spread. The experiment will employ an arrangement of broadband pick-ups (BBPs) to detect simultaneously the time structure of secondary e⁺e⁻ bunches. A spectrometer will follow the BBPs and deflect the e⁺ and e^- onto two unconventional faraday cups that will measure their charge. In addition, the energy spectrum of e⁺ and e^- distribution will be reconstructed through scintillating fibers.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP010
About •	Received ※ 05 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 25 September 2023
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MOP041	Modified Fast Orbit Feedback Controller for Disturbance Attenuation in Long Straights for Diamond-II	controls, target, electron, feedback	119
	S. Banerjee, M.G. Abbott, L. Bobb, I. Kempf DLS, Harwell, United Kingdom I. Kempf University of Oxford, Oxford, United Kingdom
	At Diamond Light Source, the fast orbit feedback (FOFB) uses one array of correctors and the controller is designed using the internal model control (IMC) structure. The Diamond-II upgrade will introduce an additional array of fast correctors and a new controller that is designed using the generalised modal decomposition, increasing the overall closed-loop bandwidth from 140 Hz to 1 kHz. Although simulation results have shown that the resulting beam displacement is within specification in all straights, they have also shown that the performance on long straights is limited, particularly in the vertical plane. In this paper, the controller is tuned in order to increase the FOFB performance in long straights by introducing a mode-by-mode regularisation parameter. The performance of the controller beyond 1 kHz is assessed using new disturbance data and a new measurement noise model, showing that the Diamond-II performance criteria are met, even in the presence of measurement noise.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP041
About •	Received ※ 07 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 16 September 2023
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MOP043	Using Lag Compensator in Orbit Feedback	feedback, power-supply, vacuum, operation	123
	I. Pinayev BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy Growing demand on the beam orbit stability requires higher loop gain within the operational bandwidth. Increasing the gain leads to the increase of the unity gain frequency and creates problems with systems stability due to the additional phase shifts caused by the trims (power supplies, eddy currents in vacuum chambers, etc.) and filtering of beam position data. Conventionally employed systems have 20 dB/decade slope near the unity gain providing 90 degrees phase shift which is sufficient for stability. Utilizing one or more lag compensators allows to increase the gain at low frequencies while keeping phase margin acceptable. The paper provides more details on the proposed solution as well as simulations of how the transients will be modified.
	Poster MOP043 [0.230 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP043
About •	Received ※ 25 August 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 23 September 2023
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TUP004	Detector Response Studies of the ESS Ionization Chamber	detector, linac, neutron, target	183
	I. Dolenc Kittelmann, V. Grishin ESS, Lund, Sweden P. Boutachkov GSI, Darmstadt, Germany E. Effinger, A.T. Lernevall, W. Viganò, C. Zamantzas CERN, Meyrin, Switzerland
	The European Spallation Source (ESS), currently under construction in Lund, Sweden, will be a pulsed neutron source based on a proton linac. The ESS linac is designed to deliver a 2GeV beam with peak current of 62.5mA at 14 Hz to a rotating tungsten target for neutron production. One of the most critical elements for protection of an accelerator is a Beam Loss Monitoring (BLM) system. The system is designed to protect the accelerator from beam-induced damage and unnecessary activation of the components. The main ESS BLM system is based on ionization chamber (IC) detectors. The detector was originally designed for the LHC at CERN resulting in production of 4250 monitors in 2006-2008. In 2014-2017 a new production of 830 detectors with a modified design was carried out to replenish spares for LHC and make a new series for ESS and GSI. This contribution focuses on the results from a measurement campaigns performed at the HRM (High-Radiation to Materials) facility at CERN, where detector response of the ESS type IC has been studied. The results may be of interest for other facilities, that are using existing or plan to use new generation of LHC type IC monitors as BLM detectors.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP004
About •	Received ※ 04 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 16 September 2023 — Issue date ※ 21 September 2023
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TUP006	Simulation and Shot-by-Shot Monitoring of Linac Beam Halo	electron, detector, radiation, photon	191
	A.S. Fisher, M. Bai, T. Frosio, A. Ratti, J. Smedley, J. Wu SLAC, Menlo Park, California, USA I.S. Mostafanezhad, B. Rotter Nalu Scientific, LLC, Honolulu, USA
	FELs require a reproducible distribution of the bunch core at the undulator entrance for robust and reliable lasing. However, various mechanisms drive particles from the core to form a beam halo, which can scrape the beampipe of the undulator and damage its magnets. Collimators can trim the halo, but at the 1-MHz repetition rate of SLAC’s LCLS-II superconducting linac, the collimator jaws can be activated and damaged. The Machine Protection System (MPS) can detect excessive radiation and halt the beam, but repeated MPS trips lead to significant downtime. Halo control begins by studying its structure, formation, and evolution, using a sensitive halo monitor. To that end, we are developing a pixellated diamond sensor. Diamond offers a dynamic range of up to 7 orders of magnitude, extending from the edge of the core to the faint halo expected at greater distances. Nalu Scientific has developed fast electronics for high-rate shot-by-shot readout. Initial tests are starting with a prototype 16-pixel sensor at the beam dump of SLAC’s FACET-II test facility. The tests and simulations will guide more elaborate sensor designs.
	Poster TUP006 [2.602 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP006
About •	Received ※ 07 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 12 September 2023 — Issue date ※ 19 September 2023
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TUP011	Geometry Study of an RF-Window for a GHz Transition Radiation Monitor for Longitudinal Bunch Shape Measurements	radiation, vacuum, target, FEL	209
	S. Klaproth, A. Penirschke THM, Friedberg, Germany H. De Gersem TEMF, TU Darmstadt, Darmstadt, Germany R. Singh GSI, Darmstadt, Germany
	Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract no. 05P21RORB2. Joint Project 05P2021 - R&D Accelerator (DIAGNOSE) GHz transition radiation monitors (GTRs) can be used to measure longitudinal beam profiles even for low ß beams. In comparison to traditional methods e.g., Fast Faraday Cups (FFCs) and Feschenko monitors, GTRs are a non-destructive measurement method and are able to resolve bunch-by-bunch longitudinal profiles at the same time. In our case, we plan to measure the transition radiation outside the beam line through an RF-window with an 8 GHz broad band antenna. At the border of the RF-window the transition radiation is partially reflected propagating in the beam line backwards. In this contribution, we show a study of different geometries to suppress reflections generated at the transition to the RF-window. For higher permittivity the strength of these reflections becomes stronger, simultaneously reducing the measurable signal strength at the antenna. Secondly the RF-window material must be UHV usable and should be durable like Alumina or Peek.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP011
About •	Received ※ 25 September 2023 — Revised ※ 29 September 2023 — Accepted ※ 30 September 2023 — Issue date ※ 30 September 2023
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TUP022	Characterisation of Cherenkov Diffraction Radiation Using Electro-Optical Methods	electron, radiation, experiment, laser	226
	A. Schlögelhofer, T. Lefèvre, S. Mazzoni, E. Senes CERN, Meyrin, Switzerland L. Duvillaret KAPTEOS, Sainte-Helene-du-Lac, France A. Schlögelhofer TU Vienna, Wien, Austria
	The properties of Cherenkov diffraction radiation (ChDR) have been studied extensively during the recent years to be exploited for non-invasive beam diagnostic devices for short bunches. The dependence of charge and the influence of the bunch form factor on the coherent part of the radiated spectrum have been demonstrated and studied in the past. However, the actual field strength of coherent ChDR as well as its study in time domain need further investigation. In this contribution we are using electro-optical techniques to investigate and quantify these parameters. The electro-optical read-out brings the advantage of high bandwidth acquisition and insensitivity to electromagnetic interference, whereas at the same time a large fraction of the acquisition setup can be installed and operated outside of the radiation controlled areas. We will present experimental results from the CLEAR facility at CERN as well as simulations of the peak field of the temporal profile of beam-generated ChDR pulses.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP022
About •	Received ※ 05 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 11 September 2023 — Issue date ※ 13 September 2023
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TUP028	Collimator Irradiation Studies at the Advanced Photon Source	experiment, photon, storage-ring, radiation	245
	J.C. Dooling, W. Berg, M. Borland, J.R. Calvey, L. Emery, A.M. Grannan, K.C. Harkay, Y. Lee, R.R. Lindberg, G. Navrotski, V. Sajaev, N. Sereno, J.B. Stevens, Y.P. Sun, K.P. Wootton ANL, Lemont, Illinois, USA N.M. Cook RadiaSoft LLC, Boulder, Colorado, USA D.W. Lee, S.M. Riedel UCSC, Santa Cruz, California, USA
	Funding: Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357. We present results from a recent collimator irradiation experiment conducted in the Advanced Photon Source (APS) storage ring. This experiment is the third in a series of studies to examine the effects of high-intensity electron beams on potential collimator material for the APS-Upgrade (APS-U). The intent here is to determine if a fan-out kicker can sufficiently reduce e-beam power density to protect horizontal collimators planned for the APS-U storage-ring. The fan-out kicker (FOK) spreads the bunched-beam vertically allowing it to grow in transverse dimensions prior to striking the collimator. In the present experiment, one of the two collimator test pieces is fabricated from oxygen-free copper; the other from 6061-T6 aluminum. As in past studies, diagnostics include turn-by-turn BPMs, a diagnostic image system, fast beam loss monitors, a pin-hole camera, and a current monitor. Post-irradiation analyses employ microscopy and metallurgy. To avoid confusion from multiple strikes, only three beam aborts are carried out on each of the collimator pieces; two with the FOK on and the other with it off. Observed hydrodynamic behavior will be compared with coupled codes.
	Poster TUP028 [3.733 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP028
About •	Received ※ 07 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 25 September 2023 — Issue date ※ 29 September 2023
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WE3C02	Development of a Precise 4d Emittance Meter Using Differential Slit Image Processing	emittance, experiment, electron, background	318
	B.K. Shin, G. Hahn PAL, Pohang, Republic of Korea M. Chung, C.K. Sung UNIST, Ulsan, Republic of Korea
	We have developed a highly precise 4D emittance meter for X-Y coupled beams with 4D phase-space (x-x’, y-y’, x-y’, y-x’) which utilizes an L-shaped slit and employs novel analysis techniques. Our approach involves two types of slit-screen image processing to generate pepper-pot-like images with great accuracy. One which we call the "differential slit" method, was developed by our group. This approach involves combining two slit-screen images, one at position x and the other at position x + the size of the slit, to create a differential slit image. The other method we use is the "virtual pepper-pot (VPP)" method, which combines x-slit and y-slit images to produce a hole (x,y) image. By combining that hole images, we are able to take extra x-y’ and y-x’ phase-space. The "differential slit" method is crucial for accurately measuring emittance. Through simulations with 0.1 mm slit width using Geant4, the emittance uncertainties for a 5 nm rad and 0.2 mm size electron beam were 5% and 250% with and without the "differential slit", respectively. In this presentation, we provide a description of the methodology, the design of slit, and the results of the 4D emittance measurements.
	Slides WE3C02 [4.459 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WE3C02
About •	Received ※ 30 August 2023 — Revised ※ 13 September 2023 — Accepted ※ 26 September 2023 — Issue date ※ 28 September 2023
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WEP005	Effect of Incoherent Depth of Field for Bean Halo Measurement with the Coronagraph in SuperKEKB	optics, radiation, synchrotron, synchrotron-radiation	335
	T.M. Mitsuhashi, H. Ikeda, G. Mitsuka KEK, Ibaraki, Japan
	The incoherent depth-of-field due to the instantaneous opening angle of dipole SR will reduce the spatial coherence of SR in horizontal direction in the beam size measurement by using interferometry. This reduction of spatial coherence is due to both of apparent change of the beam profile due to field depth and intensity distribution in the aperture. In the case of beam profile measurement by imaging system, observed beam profile will deform and produce a beam tail in asymmetric manner by this effect. This apparent change of beam profile, especially extra beam tail in one side has certain influence for beam halo measurement using the coronagraph, because it has a large dynamic range of 6 order magnitude. Since the magnitude of asymmetric tail is proportional to bending radius, this effect is larger in large high energy physics machine which has a long bending radius. This effect is theoretically studied and compare with coronagraph measurement result of beam halo in the SuperKEKB. As a conclusion, this effect is very small and not observable in the coronagraph measurement at SuperKEKB.
	Poster WEP005 [0.570 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP005
About •	Received ※ 05 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 21 September 2023
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WEP018	Simulation of Oscillating Arm Wire Monitor Mechanics Driven by a Stepper Motor	acceleration, damping, proton, HOM	373
	R. Dölling PSI, Villigen PSI, Switzerland
	The present oscillating arm wire monitors at HIPA operate with wire speeds of 0.75 m/s. Based on basic dynamic simulations of mechanics and motor, we discuss possible variants of this design using stepper motors in open loop control. The results suggest that 4 m/s can be reached with sufficient position resolution, when using a predefined step sequence customized to the mechanics. This speed should be sufficient to measure the full proton beam current in the injection line.
	Poster WEP018 [3.110 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP018
About •	Received ※ 06 September 2023 — Accepted ※ 10 September 2023 — Issue date ※ 01 October 2023
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WEP019	Study of Single Wire Scanner Monitor for FETS-FFA Test Ring	proton, scattering, linac, injection	377
	E. Yamakawa, S. Machida, A. Pertica, D.W. Posthuma de Boer STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom Y. Ishi Kyoto University, Research Reactor Institute, Osaka, Japan A.P. Letchford STFC/RAL, Chilton, Didcot, Oxon, United Kingdom T. Uesugi Kyoto University, Institute for Integrated Radiation and Nuclear Science, Osaka, Japan
	To confirm the use of Fixed Field Alternating gradient accelerator (FFA) as a high power pulsed neutron spallation source, a prototype called FETS-FFA is studied at Rutherford Laboratory (RAL). A single Wire Scanner Monitor (WSM) is planned to be used to measure a beam position and a beam profile in the ring. One of the concerns of this monitor is the thermal damage on the Carbon Nano Tube (CNT) wire due to high energy deposition of low energy proton beam in FETS-FFA (3 - 12 MeV). Furthermore, to measure a beam profile during beam acceleration in the ring, a diameter of CNT wire needs to be smaller than the orbit displacements in turns. To confirm whether a single WSM is suitable for FETS-FFA ring, two different beam tests were performed at RAL and at the Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS). Both measurements demonstrated that the single WSM is applicable for FETS-FFA ring if the diameter of CNT is smaller than the orbit separation in turns. In this paper, the detail of the design study of the single WSM as well as the performance tests are presented.
	Poster WEP019 [8.196 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP019
About •	Received ※ 05 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 25 September 2023 — Issue date ※ 01 October 2023
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WEP024	A Simulation of the Photoionization of H⁻ Together With the Subsequent Tracking of the Liberated Electrons	laser, electron, linac, MEBT	400
	R.M. Thurman-Keup, M. El Baz, V.E. Scarpine Fermilab, Batavia, Illinois, USA
	Funding: This work was produced by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. The Proton Improvement Plan - II (PIP-II) is a new linear accelerator (LINAC) complex being built at Fermilab. It is based on superconducting radiofrequency cavities and will accelerate H⁻ ions to 800 MeV kinetic energy before injection into the existing Booster ring. Measurements of the profile of the beam along the LINAC must be done by non-intercepting methods due to the superconducting cavities. The method chosen is photoionization of a small number of H⁻ by a focused infrared laser, aka laserwire. The number of ionized electrons is measured as a function of laser position within the H⁻ beam. To aid in the design of the collection mechanism, a simulation was written in MATLAB with input from the commercial electromagnetic simulation, CST. This simulation calculates the number and positions of the liberated electrons and tracks them through the magnetic collection and H⁻ beam fields to the collection point. Results from this simulation for various points along the LINAC will be shown.
	Poster WEP024 [7.451 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP024
About •	Received ※ 08 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 12 September 2023 — Issue date ※ 30 September 2023
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WEP027	Status of Gas Sheet Monitor for Profile Measurements at FRIB	photon, optics, heavy-ion, vacuum	410
	A. Lokey, S.M. Lidia FRIB, East Lansing, Michigan, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University. We report on the status of work on a non-invasive profile monitor under development for use at the Facility for Rare Isotope Beams (FRIB), a heavy-ion LINAC which produces high-intensity, multi-charge state beams. The measurement will be made by collecting photons generated at the interaction point of the beam and a collimated molecular gas curtain. These photons will be collected with an intensified camera system, generating a two dimensional image and allowing for measurements of profile, beam halo, and other properties more prevalent at specific locations of interest, such as charge state spread after folding segment bends. Included will be ongoing design specifications, simulation results, and discussion of measurement techniques for acquiring signal from the device.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP027
About •	Received ※ 07 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 12 September 2023 — Issue date ※ 14 September 2023
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WEP034	Effect of Longitudinal Beam-Coupling Impedance on the Schottky Spectrum of Bunched Beams	synchrotron, impedance, coupling, proton	428
	C. Lannoy, D. Alves, K. Łasocha, N. Mounet CERN, Meyrin, Switzerland C. Lannoy, T. Pieloni EPFL, Lausanne, Switzerland
	Schottky spectra can be strongly affected by collective effects, in particular those arising from beam-coupling impedance when a large number of bunch charges are involved. In such conditions, the direct interpretation of the measured spectra becomes difficult, which prevents the extraction of beam and machine parameters in the same way as is usually done for lower bunch charges. Since no theory is yet directly applicable to predict the impact of impedance on such spectra, we use here time-domain, macro-particle simulations and apply a semi-analytical method to compute the Schottky spectrum for various machine and beam conditions, such as the ones found at the Large Hadron Collider. A simple longitudinal resonator-like impedance model is introduced in the simulations and its effect studied in different configurations, allowing preliminary interpretations of the impact of longitudinal impedance on Schottky spectra.
	Poster WEP034 [1.237 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP034
About •	Received ※ 05 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 22 September 2023
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WEP035	Statistical Properties of Schottky Spectra	synchrotron, betatron, dipole, diagnostics	433
	C. Lannoy, D. Alves, K. Łasocha, N. Mounet CERN, Meyrin, Switzerland C. Lannoy, T. Pieloni EPFL, Lausanne, Switzerland
	Schottky signals are used for non-invasive beam diagnostics as they contain information on various beam and machine parameters. The instantaneous Schottky signal is, however, only a single realisation of a random process, implicitly depending on the discrete distribution of synchrotron and betatron amplitudes and phases among the particles. To estimate the expected value of the Schottky power spectrum, and reveal the inner structure of the Bessel satellites described by the theory, the averaging of instantaneous Schottky spectra is required. This study describes this procedure quantitatively by analysing the statistical properties of the Schottky signals, including the expected value and variance of Schottky power spectra. Furthermore, we investigate how these quantities evolve with the number of particles in the bunch, the observed harmonic of the revolution frequency, the distribution of synchrotron oscillation amplitudes, and the bunch profile. The theoretical findings are compared against macro-particle simulations as well as Monte Carlo computations.
	Poster WEP035 [3.908 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP035
About •	Received ※ 05 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 29 September 2023
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MO2I02

Fast Orbit Feedback for Diamond-II

controls, storage-ring, feedback, electron

1

I. Kempf, M.G. Abbott, L. Bobb, G.B. Christian
DLS, Harwell, United Kingdom
S. Duncan
University of Oxford, Oxford, United Kingdom
G. Rehm
HZB, Berlin, Germany

Funding: Diamond Light Source and Engineering and Physical Sciences Research Council
The electron beam stability is critical for 4th generation light sources. As opposed to 10% of beam size up to 140 Hz at Diamond, advances in detector speed and resolution at Diamond-II increase the stability requirements to 3% up to 1 kHz. This paper presents a novel control methodology for the fast orbit feedback at Diamond-II, which will stabilise the beam using two arrays of 252 slow and 144 fast correctors and 252 beam position monitors at 100 kHz. In contrast to existing approaches that separate slow and fast feedback loops, our approach is based on a two-matrix factorisation called the generalised singular value decomposition (GSVD), which decouples the system into 144 two-input modes controlled by slow and fast magnets and 108 modes controlled by slow magnets only. The GSVD-based controller is implemented in the existing Diamond storage ring using a centralised communication architecture, such as planned for Diamond-II. We present results from the Diamond storage ring and simulation, which confirm that the proposed approach meets the target specification for Diamond-II.

Slides MO2I02 [3.686 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO2I02

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Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 11 September 2023 — Issue date ※ 18 September 2023

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MOP002

MiniBEE - Minibeam Beamline for Preclinical Experiments

proton, radiation, target, cyclotron

34

J. Reindl, G. Datzmann, G. Dollinger, J. Neubauer, A. Rousseti
Universität der Bundeswehr Muenchen, Neubiberg, Germany
J. Bundesmann, A. Denker, A. Dittwald, G. Kourkafas
HZB, Berlin, Germany
G. Datzmann
Datzmann Interact & Innovate GmbH, München, Germany
A. Denker
BHT, Berlin, Germany

Spatial fractionated radiotherapy using protons, so-called proton minibeam radiotherapy (pMBT) was developed for better sparing of normal tissue in the entrance channel of radiation. Progressing towards clinical use, pMBT should overcome current technical and biomedical limitations. This work discusses a preclinical pMBT facility, currently built at the 68.5MeV cyclotron at the Helmholtz Zentrum Berlin. The goal is to irradiate small animals using focused pMBT with a σ of 50µm, a high peak-to-valley dose ratio at center-to-center distance as small as 1mm and beam current of 1nA. A first degrader defines the maximum energy of the beam. Dipole magnets and quadrupole triplets transport the beam to the treatment room while multiple slits properly form the transverse beam profiles. A high magnetic field gradient triplet lens forms the minibeams in front of the target station and, scanning magnets are used for a raster scan at the target. An additional degrader, positioned close before the focusing spot and the target, further reduces the energy, forming a spread-out Bragg peak. A small animal radiation research platform will be used for imaging and positioning of the target.

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP002

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Received ※ 09 September 2023 — Revised ※ 14 September 2023 — Accepted ※ 25 September 2023 — Issue date ※ 29 September 2023

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MOP004

Design and Study of Cavity Quadrupole Moment and Energy Spread Monitor

cavity, quadrupole, framework, linac

37

Q. Wang, Q.Y. Dong, L.T. Huang
DICP, Dalian, Liaoning, People’s Republic of China
Q. Luo
USTC/NSRL, Hefei, Anhui, People’s Republic of China

A nondestructive method to measure beam energy spread using the quadrupole modes within a microwave cavity is proposed. Compared with a button beam position monitor (BBPM) or a stripline beam position monitor (SBPM), the cavity monitor is a narrow band pickup and therefore has better signal-to-noise ratio (SNR) and resolution. In this study, a rectangular cavity monitor is designed. TM220 mode operating at 4.76 GHz in the cavity reflects the quadrupole moment of the beam. The cavity plans to be installed behind a bending magnet in Dalian Coherent Light Source (DCLS), an extreme ultraviolet FEL facility. In this position, the beam has a larger dispersion, which is beneficial to measure the energy spread. A quadrupole magnet, a fluorescent screen, and a SBPM with eight electrodes is installed near the cavity for calibration and comparison. The systematic framework and simulation results are also discussed in this paper.

Poster MOP004 [0.882 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP004

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Received ※ 13 July 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 28 September 2023

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MOP010

Diagnostics for a High Emittance and High Energy Spread Positron Source

diagnostics, pick-up, positron, experiment

54

N. Vallis, P. Craievich, R.F. Fortunati, R. Ischebeck, E. Ismaili, P.N. Juranič, F. Marcellini, G.L. Orlandi, M. Schaer, R. Zennaro, M. Zykova
PSI, Villigen PSI, Switzerland

Funding: This work was done under the auspices of CHART (chart.ch)
This paper is an overview of a diagnostics setup for highly spread e⁺e⁻ beams, to be installed at the PSI Positron Production (P³ or P-cubed) experiment. To be hosted at the SwissFEL facility (PSI, Switzerland) in 2026, P³ is e⁺ source demonstrator designed to generate, capture, separate and detect nano-Coulombs of secondary e⁺ and e^- bunches, in spite of their extreme tranverse emittance and energy spread. The experiment will employ an arrangement of broadband pick-ups (BBPs) to detect simultaneously the time structure of secondary e⁺e⁻ bunches. A spectrometer will follow the BBPs and deflect the e⁺ and e^- onto two unconventional faraday cups that will measure their charge. In addition, the energy spectrum of e⁺ and e^- distribution will be reconstructed through scintillating fibers.

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP010

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Received ※ 05 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 25 September 2023

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MOP041

Modified Fast Orbit Feedback Controller for Disturbance Attenuation in Long Straights for Diamond-II

controls, target, electron, feedback

119

S. Banerjee, M.G. Abbott, L. Bobb, I. Kempf
DLS, Harwell, United Kingdom
I. Kempf
University of Oxford, Oxford, United Kingdom

At Diamond Light Source, the fast orbit feedback (FOFB) uses one array of correctors and the controller is designed using the internal model control (IMC) structure. The Diamond-II upgrade will introduce an additional array of fast correctors and a new controller that is designed using the generalised modal decomposition, increasing the overall closed-loop bandwidth from 140 Hz to 1 kHz. Although simulation results have shown that the resulting beam displacement is within specification in all straights, they have also shown that the performance on long straights is limited, particularly in the vertical plane. In this paper, the controller is tuned in order to increase the FOFB performance in long straights by introducing a mode-by-mode regularisation parameter. The performance of the controller beyond 1 kHz is assessed using new disturbance data and a new measurement noise model, showing that the Diamond-II performance criteria are met, even in the presence of measurement noise.

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP041

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Received ※ 07 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 16 September 2023

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MOP043

Using Lag Compensator in Orbit Feedback

feedback, power-supply, vacuum, operation

123

I. Pinayev
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
Growing demand on the beam orbit stability requires higher loop gain within the operational bandwidth. Increasing the gain leads to the increase of the unity gain frequency and creates problems with systems stability due to the additional phase shifts caused by the trims (power supplies, eddy currents in vacuum chambers, etc.) and filtering of beam position data. Conventionally employed systems have 20 dB/decade slope near the unity gain providing 90 degrees phase shift which is sufficient for stability. Utilizing one or more lag compensators allows to increase the gain at low frequencies while keeping phase margin acceptable. The paper provides more details on the proposed solution as well as simulations of how the transients will be modified.

Poster MOP043 [0.230 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP043

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Received ※ 25 August 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 23 September 2023

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TUP004

Detector Response Studies of the ESS Ionization Chamber

detector, linac, neutron, target

183

I. Dolenc Kittelmann, V. Grishin
ESS, Lund, Sweden
P. Boutachkov
GSI, Darmstadt, Germany
E. Effinger, A.T. Lernevall, W. Viganò, C. Zamantzas
CERN, Meyrin, Switzerland

The European Spallation Source (ESS), currently under construction in Lund, Sweden, will be a pulsed neutron source based on a proton linac. The ESS linac is designed to deliver a 2GeV beam with peak current of 62.5mA at 14 Hz to a rotating tungsten target for neutron production. One of the most critical elements for protection of an accelerator is a Beam Loss Monitoring (BLM) system. The system is designed to protect the accelerator from beam-induced damage and unnecessary activation of the components. The main ESS BLM system is based on ionization chamber (IC) detectors. The detector was originally designed for the LHC at CERN resulting in production of 4250 monitors in 2006-2008. In 2014-2017 a new production of 830 detectors with a modified design was carried out to replenish spares for LHC and make a new series for ESS and GSI. This contribution focuses on the results from a measurement campaigns performed at the HRM (High-Radiation to Materials) facility at CERN, where detector response of the ESS type IC has been studied. The results may be of interest for other facilities, that are using existing or plan to use new generation of LHC type IC monitors as BLM detectors.

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP004

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Received ※ 04 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 16 September 2023 — Issue date ※ 21 September 2023

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TUP006

Simulation and Shot-by-Shot Monitoring of Linac Beam Halo

electron, detector, radiation, photon

191

A.S. Fisher, M. Bai, T. Frosio, A. Ratti, J. Smedley, J. Wu
SLAC, Menlo Park, California, USA
I.S. Mostafanezhad, B. Rotter
Nalu Scientific, LLC, Honolulu, USA

FELs require a reproducible distribution of the bunch core at the undulator entrance for robust and reliable lasing. However, various mechanisms drive particles from the core to form a beam halo, which can scrape the beampipe of the undulator and damage its magnets. Collimators can trim the halo, but at the 1-MHz repetition rate of SLAC’s LCLS-II superconducting linac, the collimator jaws can be activated and damaged. The Machine Protection System (MPS) can detect excessive radiation and halt the beam, but repeated MPS trips lead to significant downtime. Halo control begins by studying its structure, formation, and evolution, using a sensitive halo monitor. To that end, we are developing a pixellated diamond sensor. Diamond offers a dynamic range of up to 7 orders of magnitude, extending from the edge of the core to the faint halo expected at greater distances. Nalu Scientific has developed fast electronics for high-rate shot-by-shot readout. Initial tests are starting with a prototype 16-pixel sensor at the beam dump of SLAC’s FACET-II test facility. The tests and simulations will guide more elaborate sensor designs.

Poster TUP006 [2.602 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP006

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Received ※ 07 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 12 September 2023 — Issue date ※ 19 September 2023

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TUP011

Geometry Study of an RF-Window for a GHz Transition Radiation Monitor for Longitudinal Bunch Shape Measurements

radiation, vacuum, target, FEL

209

S. Klaproth, A. Penirschke
THM, Friedberg, Germany
H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
R. Singh
GSI, Darmstadt, Germany

Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract no. 05P21RORB2. Joint Project 05P2021 - R&D Accelerator (DIAGNOSE)
GHz transition radiation monitors (GTRs) can be used to measure longitudinal beam profiles even for low ß beams. In comparison to traditional methods e.g., Fast Faraday Cups (FFCs) and Feschenko monitors, GTRs are a non-destructive measurement method and are able to resolve bunch-by-bunch longitudinal profiles at the same time. In our case, we plan to measure the transition radiation outside the beam line through an RF-window with an 8 GHz broad band antenna. At the border of the RF-window the transition radiation is partially reflected propagating in the beam line backwards. In this contribution, we show a study of different geometries to suppress reflections generated at the transition to the RF-window. For higher permittivity the strength of these reflections becomes stronger, simultaneously reducing the measurable signal strength at the antenna. Secondly the RF-window material must be UHV usable and should be durable like Alumina or Peek.

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP011

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Received ※ 25 September 2023 — Revised ※ 29 September 2023 — Accepted ※ 30 September 2023 — Issue date ※ 30 September 2023

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TUP022

Characterisation of Cherenkov Diffraction Radiation Using Electro-Optical Methods

electron, radiation, experiment, laser

226

A. Schlögelhofer, T. Lefèvre, S. Mazzoni, E. Senes
CERN, Meyrin, Switzerland
L. Duvillaret
KAPTEOS, Sainte-Helene-du-Lac, France
A. Schlögelhofer
TU Vienna, Wien, Austria

The properties of Cherenkov diffraction radiation (ChDR) have been studied extensively during the recent years to be exploited for non-invasive beam diagnostic devices for short bunches. The dependence of charge and the influence of the bunch form factor on the coherent part of the radiated spectrum have been demonstrated and studied in the past. However, the actual field strength of coherent ChDR as well as its study in time domain need further investigation. In this contribution we are using electro-optical techniques to investigate and quantify these parameters. The electro-optical read-out brings the advantage of high bandwidth acquisition and insensitivity to electromagnetic interference, whereas at the same time a large fraction of the acquisition setup can be installed and operated outside of the radiation controlled areas. We will present experimental results from the CLEAR facility at CERN as well as simulations of the peak field of the temporal profile of beam-generated ChDR pulses.

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP022

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Received ※ 05 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 11 September 2023 — Issue date ※ 13 September 2023

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TUP028

Collimator Irradiation Studies at the Advanced Photon Source

experiment, photon, storage-ring, radiation

245

J.C. Dooling, W. Berg, M. Borland, J.R. Calvey, L. Emery, A.M. Grannan, K.C. Harkay, Y. Lee, R.R. Lindberg, G. Navrotski, V. Sajaev, N. Sereno, J.B. Stevens, Y.P. Sun, K.P. Wootton
ANL, Lemont, Illinois, USA
N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
D.W. Lee, S.M. Riedel
UCSC, Santa Cruz, California, USA

Funding: Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357.
We present results from a recent collimator irradiation experiment conducted in the Advanced Photon Source (APS) storage ring. This experiment is the third in a series of studies to examine the effects of high-intensity electron beams on potential collimator material for the APS-Upgrade (APS-U). The intent here is to determine if a fan-out kicker can sufficiently reduce e-beam power density to protect horizontal collimators planned for the APS-U storage-ring. The fan-out kicker (FOK) spreads the bunched-beam vertically allowing it to grow in transverse dimensions prior to striking the collimator. In the present experiment, one of the two collimator test pieces is fabricated from oxygen-free copper; the other from 6061-T6 aluminum. As in past studies, diagnostics include turn-by-turn BPMs, a diagnostic image system, fast beam loss monitors, a pin-hole camera, and a current monitor. Post-irradiation analyses employ microscopy and metallurgy. To avoid confusion from multiple strikes, only three beam aborts are carried out on each of the collimator pieces; two with the FOK on and the other with it off. Observed hydrodynamic behavior will be compared with coupled codes.

Poster TUP028 [3.733 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP028

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Received ※ 07 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 25 September 2023 — Issue date ※ 29 September 2023

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WE3C02

Development of a Precise 4d Emittance Meter Using Differential Slit Image Processing

emittance, experiment, electron, background

318

B.K. Shin, G. Hahn
PAL, Pohang, Republic of Korea
M. Chung, C.K. Sung
UNIST, Ulsan, Republic of Korea

We have developed a highly precise 4D emittance meter for X-Y coupled beams with 4D phase-space (x-x’, y-y’, x-y’, y-x’) which utilizes an L-shaped slit and employs novel analysis techniques. Our approach involves two types of slit-screen image processing to generate pepper-pot-like images with great accuracy. One which we call the "differential slit" method, was developed by our group. This approach involves combining two slit-screen images, one at position x and the other at position x + the size of the slit, to create a differential slit image. The other method we use is the "virtual pepper-pot (VPP)" method, which combines x-slit and y-slit images to produce a hole (x,y) image. By combining that hole images, we are able to take extra x-y’ and y-x’ phase-space. The "differential slit" method is crucial for accurately measuring emittance. Through simulations with 0.1 mm slit width using Geant4, the emittance uncertainties for a 5 nm rad and 0.2 mm size electron beam were 5% and 250% with and without the "differential slit", respectively. In this presentation, we provide a description of the methodology, the design of slit, and the results of the 4D emittance measurements.

Slides WE3C02 [4.459 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WE3C02

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Received ※ 30 August 2023 — Revised ※ 13 September 2023 — Accepted ※ 26 September 2023 — Issue date ※ 28 September 2023

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WEP005

Effect of Incoherent Depth of Field for Bean Halo Measurement with the Coronagraph in SuperKEKB

optics, radiation, synchrotron, synchrotron-radiation

335

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

The incoherent depth-of-field due to the instantaneous opening angle of dipole SR will reduce the spatial coherence of SR in horizontal direction in the beam size measurement by using interferometry. This reduction of spatial coherence is due to both of apparent change of the beam profile due to field depth and intensity distribution in the aperture. In the case of beam profile measurement by imaging system, observed beam profile will deform and produce a beam tail in asymmetric manner by this effect. This apparent change of beam profile, especially extra beam tail in one side has certain influence for beam halo measurement using the coronagraph, because it has a large dynamic range of 6 order magnitude. Since the magnitude of asymmetric tail is proportional to bending radius, this effect is larger in large high energy physics machine which has a long bending radius. This effect is theoretically studied and compare with coronagraph measurement result of beam halo in the SuperKEKB. As a conclusion, this effect is very small and not observable in the coronagraph measurement at SuperKEKB.

Poster WEP005 [0.570 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP005

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Received ※ 05 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 21 September 2023

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WEP018

Simulation of Oscillating Arm Wire Monitor Mechanics Driven by a Stepper Motor

acceleration, damping, proton, HOM

373

R. Dölling
PSI, Villigen PSI, Switzerland

The present oscillating arm wire monitors at HIPA operate with wire speeds of 0.75 m/s. Based on basic dynamic simulations of mechanics and motor, we discuss possible variants of this design using stepper motors in open loop control. The results suggest that 4 m/s can be reached with sufficient position resolution, when using a predefined step sequence customized to the mechanics. This speed should be sufficient to measure the full proton beam current in the injection line.

Poster WEP018 [3.110 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP018

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Received ※ 06 September 2023 — Accepted ※ 10 September 2023 — Issue date ※ 01 October 2023

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WEP019

Study of Single Wire Scanner Monitor for FETS-FFA Test Ring

proton, scattering, linac, injection

377

E. Yamakawa, S. Machida, A. Pertica, D.W. Posthuma de Boer
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
Y. Ishi
Kyoto University, Research Reactor Institute, Osaka, Japan
A.P. Letchford
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
T. Uesugi
Kyoto University, Institute for Integrated Radiation and Nuclear Science, Osaka, Japan

To confirm the use of Fixed Field Alternating gradient accelerator (FFA) as a high power pulsed neutron spallation source, a prototype called FETS-FFA is studied at Rutherford Laboratory (RAL). A single Wire Scanner Monitor (WSM) is planned to be used to measure a beam position and a beam profile in the ring. One of the concerns of this monitor is the thermal damage on the Carbon Nano Tube (CNT) wire due to high energy deposition of low energy proton beam in FETS-FFA (3 - 12 MeV). Furthermore, to measure a beam profile during beam acceleration in the ring, a diameter of CNT wire needs to be smaller than the orbit displacements in turns. To confirm whether a single WSM is suitable for FETS-FFA ring, two different beam tests were performed at RAL and at the Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS). Both measurements demonstrated that the single WSM is applicable for FETS-FFA ring if the diameter of CNT is smaller than the orbit separation in turns. In this paper, the detail of the design study of the single WSM as well as the performance tests are presented.

Poster WEP019 [8.196 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP019

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Received ※ 05 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 25 September 2023 — Issue date ※ 01 October 2023

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WEP024

A Simulation of the Photoionization of H⁻ Together With the Subsequent Tracking of the Liberated Electrons

laser, electron, linac, MEBT

400

R.M. Thurman-Keup, M. El Baz, V.E. Scarpine
Fermilab, Batavia, Illinois, USA

Funding: This work was produced by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
The Proton Improvement Plan - II (PIP-II) is a new linear accelerator (LINAC) complex being built at Fermilab. It is based on superconducting radiofrequency cavities and will accelerate H⁻ ions to 800 MeV kinetic energy before injection into the existing Booster ring. Measurements of the profile of the beam along the LINAC must be done by non-intercepting methods due to the superconducting cavities. The method chosen is photoionization of a small number of H⁻ by a focused infrared laser, aka laserwire. The number of ionized electrons is measured as a function of laser position within the H⁻ beam. To aid in the design of the collection mechanism, a simulation was written in MATLAB with input from the commercial electromagnetic simulation, CST. This simulation calculates the number and positions of the liberated electrons and tracks them through the magnetic collection and H⁻ beam fields to the collection point. Results from this simulation for various points along the LINAC will be shown.

Poster WEP024 [7.451 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP024

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Received ※ 08 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 12 September 2023 — Issue date ※ 30 September 2023

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WEP027

Status of Gas Sheet Monitor for Profile Measurements at FRIB

photon, optics, heavy-ion, vacuum

410

A. Lokey, S.M. Lidia
FRIB, East Lansing, Michigan, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
We report on the status of work on a non-invasive profile monitor under development for use at the Facility for Rare Isotope Beams (FRIB), a heavy-ion LINAC which produces high-intensity, multi-charge state beams. The measurement will be made by collecting photons generated at the interaction point of the beam and a collimated molecular gas curtain. These photons will be collected with an intensified camera system, generating a two dimensional image and allowing for measurements of profile, beam halo, and other properties more prevalent at specific locations of interest, such as charge state spread after folding segment bends. Included will be ongoing design specifications, simulation results, and discussion of measurement techniques for acquiring signal from the device.

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP027

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Received ※ 07 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 12 September 2023 — Issue date ※ 14 September 2023

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WEP034

Effect of Longitudinal Beam-Coupling Impedance on the Schottky Spectrum of Bunched Beams

synchrotron, impedance, coupling, proton

428

C. Lannoy, D. Alves, K. Łasocha, N. Mounet
CERN, Meyrin, Switzerland
C. Lannoy, T. Pieloni
EPFL, Lausanne, Switzerland

Schottky spectra can be strongly affected by collective effects, in particular those arising from beam-coupling impedance when a large number of bunch charges are involved. In such conditions, the direct interpretation of the measured spectra becomes difficult, which prevents the extraction of beam and machine parameters in the same way as is usually done for lower bunch charges. Since no theory is yet directly applicable to predict the impact of impedance on such spectra, we use here time-domain, macro-particle simulations and apply a semi-analytical method to compute the Schottky spectrum for various machine and beam conditions, such as the ones found at the Large Hadron Collider. A simple longitudinal resonator-like impedance model is introduced in the simulations and its effect studied in different configurations, allowing preliminary interpretations of the impact of longitudinal impedance on Schottky spectra.

Poster WEP034 [1.237 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP034

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Received ※ 05 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 22 September 2023

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WEP035

Statistical Properties of Schottky Spectra

synchrotron, betatron, dipole, diagnostics

433

C. Lannoy, D. Alves, K. Łasocha, N. Mounet
CERN, Meyrin, Switzerland
C. Lannoy, T. Pieloni
EPFL, Lausanne, Switzerland

Schottky signals are used for non-invasive beam diagnostics as they contain information on various beam and machine parameters. The instantaneous Schottky signal is, however, only a single realisation of a random process, implicitly depending on the discrete distribution of synchrotron and betatron amplitudes and phases among the particles. To estimate the expected value of the Schottky power spectrum, and reveal the inner structure of the Bessel satellites described by the theory, the averaging of instantaneous Schottky spectra is required. This study describes this procedure quantitatively by analysing the statistical properties of the Schottky signals, including the expected value and variance of Schottky power spectra. Furthermore, we investigate how these quantities evolve with the number of particles in the bunch, the observed harmonic of the revolution frequency, the distribution of synchrotron oscillation amplitudes, and the bunch profile. The theoretical findings are compared against macro-particle simulations as well as Monte Carlo computations.

Poster WEP035 [3.908 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP035

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Received ※ 05 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 29 September 2023

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