IPAC2021 - List of Keywords (emittance)

Paper	Title	Other Keywords	Page
MOXA02	Status of the APS-U Project	lattice, injection, storage-ring, photon	7
	R.O. Hettel ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Sci- ence, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357. The Advanced Photon Source Upgrade (APS-U) project at the Argonne National Laboratory will re-place the existing 7-GeV, 1.1-km circumference dou-ble bend storage ring lattice with a new 6-GeV hybrid 7BA lattice that will reduce horizontal electron emit-tance from 3 nm-rad to 42 pm-rad, including IBS ef-fects for 200-mA operation. With new optimized per-manent magnet and superconducting undulators, an increase in spectral brightness of two to three orders of magnitude in the 10-100 keV X-ray energy range will be realized. The project includes nine new high performance beamlines and fifteen enhanced beam-lines that will exploit the high brightness and coher-ence of the new facility. The project is in full swing, more than 50% complete by cost, and is on schedule for first beam sometime in mid-2024, a slip of 10 months from the original schedule due to the impact of COVID-19. Project status, challenges and outstanding issues will be discussed in this article.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXA02
About •	paper received ※ 21 May 2021 paper accepted ※ 09 June 2021 issue date ※ 11 August 2021
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MOPAB004	JSPEC - A Simulation Program for IBS and Electron Cooling	electron, simulation, experiment, scattering	49
	H. Zhang, S.V. Benson, M.W. Bruker, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. Intrabeam scattering is an important collective effect that can deteriorate the properties of a high-intensity beam, and electron cooling is a method to mitigate the IBS effect. JSPEC (JLab Simulation Package for Electron Cooling) is an open-source program developed at Jefferson Lab, which simulates the evolution of the ion beam under the IBS and/or the electron cooling effect. JSPEC has been benchmarked with BETACOOL and experimental data. In this report, we will introduce the features of JSPEC, including the friction force calculation, the IBS expansion rate and electron cooling rate calculation, and the beam-dynamic simulations for the electron cooling process; explain how to set up the simulations in JSPEC; and demonstrate the benchmarking results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB004
About •	paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 27 August 2021
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MOPAB010	RHIC Beam Energy Scan Operation with Electron Cooling in 2020	operation, luminosity, electron, experiment	72
	C. Liu, P. Adams, E.N. Beebe, S. Binello, I. Blackler, M. Blaskiewicz, K.A. Brown, D. Bruno, B.D. Coe, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, C.E. Giorgio, X. Gu, T. Hayes, K. Hock, H. Huang, R.L. Hulsart, T. Kanesue, D. Kayran, N.A. Kling, B. Lepore, Y. Luo, D. Maffei, G.J. Marr, A. Marusic, K. Mernick, R.J. Michnoff, M.G. Minty, J. Morris, C. Naylor, S. Nemesure, M. Okamura, I. Pinayev, S. Polizzo, D. Raparia, G. Robert-Demolaize, T. Roser, J. Sandberg, V. Schoefer, S. Seletskiy, F. Severino, T.C. Shrey, P. Thieberger, M. Valette, A. Zaltsman, I. Zane, K. Zeno, W. Zhang 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. RHIC provided Au-Au collisions at beam energies of 5.75 and 4.59 GeV/nucleon for the physics program in 2020 as a part of the Beam Energy Scan II experiment. The operational experience at these energies will be reported with emphasis on their unique features. These unique features include the addition of a third harmonic RF system to enable a large longitudinal acceptance at 5.75 GeV/nucleon, the application of additional lower frequency cavities for alleviating space charge effects, and the world-first operation of cooling with an RF-accelerated bunched electron beam.
	Poster MOPAB010 [3.523 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB010
About •	paper received ※ 17 May 2021 paper accepted ※ 29 July 2021 issue date ※ 10 August 2021
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MOPAB016	Small Longitudinal Emittance Setup in Injectors with Gold Beam for Beam Energy Scan in RHIC	operation, luminosity, extraction, cavity	90
	H. Huang, C.J. Gardner, C. Liu, V. Schoefer, K. Zeno BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In recent years, RHIC physics program calls for gold beam collisions with energies at and lower than the nominal RHIC injection energy. To get shorter bunches at the three higher energies (9.8GeV/c, 7.3GeV/c and 4.75GeV/c), RHIC 28MHz cavities were used. The longitudinal emittance out of injectors needs to fit in the 28MHz cavities in RHIC. At two lower energies (4.6 and 3.85 GeV/c), the 9MHz RF cavities were used, which set different requirements from injectors. Extensive beam studies were carried out to establish needed beam parameters, such as bunch intensities and longitudinal emittances. In general, enough intensity can be provided for all energies within the longitudinal emittance constraint. This paper summarizes the recent injector operation experiences for various energies.
	Poster MOPAB016 [2.641 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB016
About •	paper received ※ 16 May 2021 paper accepted ※ 17 August 2021 issue date ※ 01 September 2021
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MOPAB019	Possible Application of Round-to-Flat Hadron Beam Creation Using 3rd Order Coupling Resonances for the Electron-Ion Collider	resonance, sextupole, coupling, electron	99
	J. Kallestrup PSI, Villigen PSI, Switzerland X. Gu 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. An Electron-Ion Collider (EIC) is planned to be built in Brookhaven National Laboratory with the contribution from Jefferson National Laboratory. To have a high luminosity, both the EIC ion bunch and the EIC electron bunch are designed to be flat during their collision. The existing injector source provides a round beam of width 2.5 um rad transverse emittances. In this paper we investigate the option of dynamically crossing the 2Qx-Qy coupling resonance in order to create a flat-beam with emittance ratio Ex/Ey of up to 4. Furthermore, we explore the possibility of using a pulsed- or AC skew sextupole magnets to achieve a similar effect. Using one of these methods for flat beam creation will help lower the ion beam cooling time.
	Poster MOPAB019 [0.323 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB019
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021
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MOPAB020	Improvements to the SLS Booster Synchrotron Performance Towards SLS 2.0	booster, sextupole, coupling, injection	103
	J. Kallestrup, M. Aiba PSI, Villigen PSI, Switzerland
	The Swiss Light Source (SLS) storage ring will undergo a major upgrade to a multi-bend achromat lattice. The existing injector complex will be reused with few modifications. However, the SLS booster synchrotron has not been studied since the initial commissioning in years 2000-2001. We plan to apply an emittance exchange in the booster to lower the horizontal emittance, which is a critial parameter for the injection. Here, we present improvements to the SLS booster as a preparation for SLS 2.0 upgrade project. The vertical beam size is decreased by 50\% by the use of vertical orbit correctors without beam position monitors, leading also to suppression of vertical dispersion and a factor 10 reduction of the transverse coupling coefficient. The emittance exchange reflected these improvements in the horizontal emittance, achieving a factor of 9-10 reduction. Lastly, a fast head-tail instability limiting the injection rate into the storage ring is discovered and subsequently suppressed by correcting the chromaticities.
	Poster MOPAB020 [0.380 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB020
About •	paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 30 August 2021
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MOPAB021	A Dispersive Quadrupole Scan Technique for Transverse Beam Characterization	quadrupole, SRF, optics, booster	107
	J. Kallestrup, M. Aiba PSI, Villigen PSI, Switzerland N. Carmignani, T.P. Perron ESRF, Grenoble, France
	Quadrupole scans are one of the standard techniques to characterize the transverse beam properties in transfer lines or linacs. However, in the presence of dispersion the usage of regular quadrupole scans will lead to erroneous estimates of the beam parameters. The standard solution to this problem is to measure the dispersion and then subtract it in the post-analysis of the quadrupole scan measurements assuming the design energy spread. Here we show that the dispersive contribution to the beam size can be included in the quadrupole scan procedure, forming a linear system of equations that can be solved to obtain both the betatronic and dispersive beam parameters. The method is tested at both the SLS and ESRF booster-to-ring transfer lines leading to reasonable estimates of the beam parameters.
	Poster MOPAB021 [0.447 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB021
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 19 August 2021
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MOPAB023	Experimental Test of a New Method to Verify Retraction Margins Between Dump Absorbers and Tertiary Collimators at the LHC	experiment, alignment, beam-losses, operation	115
	C. Wiesner, W. Bartmann, C. Bracco, R. Bruce, J. Molson, M. Schaumann, C. Staufenbiel, J.A. Uythoven, M. Valette, J. Wenninger, D. Wollmann, M. Zerlauth CERN, Meyrin, Switzerland
	The protection of the tertiary collimators (TCTs) and the LHC triplet aperture in case of a so-called asynchronous beam dump relies on the correct retraction between the TCTs and the dump region absorbers. A new method to validate this retraction has been proposed, and a proof-of-principle experiment was performed at the LHC. The method uses a long orbit bump to mimic the change of the beam trajectory caused by an asynchronous firing of the extraction kickers. It can, thus, be performed with circulating beam. This paper reports on the performed beam measurements, compares them with expectations and discusses the potential benefits of the new method for machine protection.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB023
About •	paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 24 August 2021
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MOPAB029	Burn-Off with Asymmetric Interaction Points	luminosity, experiment, simulation, controls	138
	R. Tomás García, I. Efthymiopoulos, G. Iadarola CERN, Geneva, Switzerland
	LHC can host above 2700 proton bunches per ring providing collisions in the ATLAS, CMS, LHCb and ALICE interaction points. ATLAS and CMS are placed symmetrically so that they feature the same colliding bunch pairs. However this is not the case for LHCb, hence introducing unwanted bunch-by-bunch variations of the bunch intensity as the physics fill evolves. We present first analytical derivations, numerical simulations and experimental data in different bunch train collision configurations.
	Poster MOPAB029 [1.502 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB029
About •	paper received ※ 13 May 2021 paper accepted ※ 25 May 2021 issue date ※ 27 August 2021
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MOPAB032	Estimates of Collective Effects for the FCC-e⁺e⁻ Pre-Booster Ring	impedance, electron, injection, collective-effects	148
	O. Etisken, F. Antoniou, K. Oide, Y. Papaphilippou, F. Zimmermann CERN, Geneva, Switzerland A.K. Çiftçi Izmir University of Economics, Balçova/Izmir, Turkey
	The FCC-e⁺e⁻ injector complex needs to produce and to transport high-intensity e⁺ and e^- beams at a fast repetition rate for topping up the collider at its collision energy. Two different options are under consideration as pre-accelerator before the bunches are transferred to the high-energy booster: either using the existing SPS machine or designing a completely new ring. The purpose of this paper is to present the studies of collective effects with analytical estimates for both the pre-booster ring design options including space charge (SC), longitudinal micro-wave instability (LMI), transverse mode coupling instability (TMCI), ion effects, electron cloud (e-cloud), coherent synchrotron radiation (CSR), and intra-beam scattering (IBS).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB032
About •	paper received ※ 17 May 2021 paper accepted ※ 27 May 2021 issue date ※ 15 August 2021
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MOPAB033	Monochromatization of e⁺e⁻ Colliders with a Large Crossing Angle	resonance, collider, luminosity, radiation	152
	V.I. Telnov BINP SB RAS, Novosibirsk, Russia
	The relative center-of-mass energy spread at e⁺e⁻ colliders is much larger than the widths of narrow resonances, which greatly lowers the resonance production rates of J/Psi, Psi-prime, Upsililon(nS), n=1-3. Thus, a significant reduction of the center-of-mass energy spread would open up great opportunities in the search for new physics in rare decays of narrow resonances, the search for new narrow states with small partial e⁺e⁻ width. The existing monochromatization scheme is only suitable for head-on collisions, while e⁺e⁻ colliders with crossing angles (the so-called Crab Waist collision scheme) can provide much higher luminosity. In this report, a new monochromatization method for colliders with a large crossing angle is discussed. The contribution of the beam energy spread to the spread of the center-of-mass energy is canceled by introducing an appropriate energy-angle correlation at the interaction point; the relative RMS mass spread of about (3-5)10^-6 seems possible. Limitations of the proposed method are also considered. This monochromatization scheme is very attractive for the Upsilon-meson region and below. V.I.Telnov, Monochromatization of e⁺e⁻ colliders with a large crossing angle, arXiv:2008.13668
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB033
About •	paper received ※ 22 May 2021 paper accepted ※ 26 May 2021 issue date ※ 31 August 2021
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MOPAB046	Plan for Operating the APS-Upgrade Booster with a Frequency Sweep	injection, booster, extraction, cavity	201
	J.R. Calvey, T.G. Berenc, A.R. Brill, L. Emery, T. Fors, K.C. Harkay, T.J. Madden, N. Sereno, U. Wienands ANL, Lemont, Illinois, USA A. Gu UCB, Berkeley, California, USA
	The APS-Upgrade presents several challenging demands to the booster synchrotron. Swap-out injection requires the booster to capture a high charge bunch (up to 17 nC), accelerate it to 6 GeV, and maintain a low emittance at extraction for injection into the storage ring. To accommodate these conflicting demands, the RF frequency will be ramped between injection and extraction. However, the RF cavity tuners will remain static, which means the couplers will need to withstand a high reflected power at extraction. This paper presents a plan for a system that will meet the requirements for injection efficiency, extracted emittance, and equivalent power at the coupler. Results from tracking simulations and beam studies with a frequency ramp will also be shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB046
About •	paper received ※ 28 May 2021 paper accepted ※ 02 June 2021 issue date ※ 26 August 2021
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MOPAB051	Operation of the ESRF Booster with the New EBS Storage Ring	booster, SRF, injection, operation	221
	N. Carmignani, L.R. Carver, S.M. Liuzzo, T.P. Perron, S.M. White ESRF, Grenoble, France
	The Extremely Brilliant Source (EBS) has replaced the old ESRF Storage Ring (SR) during the 2019 one-year shutdown. The injector chain, composed of a Linac, a booster synchrotron, and two transfer lines, was not replaced. Nevertheless, some major hardware upgrades were anticipated prior to the long shutdown to ensure its long-term reliability. The shutdown interventions focused on reducing the machine circumference to cope with the new RF frequency of the SR. The status of the upgraded booster will be presented with a focus on the strategy used to lower horizontal emittance especially via emittance exchange.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB051
About •	paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 25 August 2021
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MOPAB055	Generation of Coherent Attosecond X-ray Pulses in the Southern Advanced Photon Source	laser, electron, storage-ring, photon	237
	W. Liu, Y. Zhao IHEP CSNS, Guangdong Province, People’s Republic of China Y. Jiao, S. Wang IHEP, Beijing, People’s Republic of China
	Southern Advanced Photon Source (SAPS) is a fourth-generation storage ring light source that has been considered for construction in Guangdong province of China, adjacent to the China Spallation Neutron Source. As a low-emittance storage ring, the natural emittance of SAPS is below 100 pm. One of the benefits is that the brightness is about 2 orders high than 3rd generation light sources. However, like many other storage ring-based light sources, the time resolution is limited by the electron bunch length in the range of picoseconds. In this work, we propose a new scheme for the generation of coherent attoseconds X-ray pulses with a high repetition rate in SAPS. A numerical demonstration of the scheme is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB055
About •	paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021
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MOPAB056	Optimization of a TBA with Stable Optics and Minimal Longitudinal Dispersion and CSR-Induced Emittance Growth	bunching, synchrotron, quadrupole, FEL	241
	C. Zhang, Y. Jiao IHEP, Beijing, People’s Republic of China C.-Y. Tsai HUST, Wuhan, People’s Republic of China
	Funding: National Natural Science Foundation of China (No. 11922512), Youth Innovation Promotion Association of Chinese Academy of Sciences (No. Y201904), National Key R&D Program of China (No. 2016YFA0401900) In the beam transfer line which often consists of dipoles to deflect the beam trajectory, longitudinal dispersion effect and emission of coherent synchrotron radiation (CSR) will lead to beam phase space distortion, thus degrading the machine performance. In this study, optimizations of a triple-bend achromat (TBA) cell are conducted using the multi-objective particle swarm optimization (MOPSO) method to suppress the CSR-induced emittance growth and minimize the longitudinal dispersion functions up to high orders, simultaneously. For the longitudinal dispersion function, results of three optimization settings are reported, which makes the TBA design first-order, second-order, and higher-order isochronous. Furthermore, we study the shortest possible beamline length of the higher-order isochronous TBA design, which may pave the way to designing a more compact beam transfer line.
	Poster MOPAB056 [0.366 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB056
About •	paper received ※ 12 May 2021 paper accepted ※ 28 May 2021 issue date ※ 15 August 2021
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MOPAB057	Evaluation of Pulsed Septum Leakage Fields and Compensation for the Advanced Photon Source Upgrade	septum, simulation, power-supply, injection	245
	M. Borland, M.S. Jaski, J. Wang ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source upgrade is considering two options for injection: vertical-plane injection with a DC Lambertson septum and horizontal-plane injection with a pulsed septum. In the latter case, pulsed leakage fields are a concern as they will cause transient beam motion and emittance dilution. In this paper, we describe results of modeling the effect of such leakage fields on the beam. We also evaluate methods of compensating for the leakage fields, including the limited time response of correction elements. Several septum drive-pulse shapes are considered and compared.
	Poster MOPAB057 [2.066 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB057
About •	paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 02 September 2021
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MOPAB062	A Single Dipole Source for Broad-Band Soft Photon Beamlines in Diamond-II	lattice, dipole, dynamic-aperture, linear-dynamics	261
	M. Apollonio, G. Cinque, H. Ghasem, A.N. Jury, I.P.S. Martin, R. Rambo DLS, Oxfordshire, United Kingdom
	Diamond-II is a project based at Diamond Light Source for an upgrade towards a Storage Ring characterized by a reduction of a factor 20 in its natural emittance and a doubling of the number of straight sections. At Diamond-II the majority of existing beamline capacity should be maintained, while enhancing their performance thanks to the increase in brightness at the source points. The substantial modification of the lattice imposes a likewise re-design of the broad-band sources, presently based on standard dipoles. In this paper we discuss a possible solution for the IR/THz beamline B22 operating within a photon energy range between 1meV and 1eV. This proposal, ideal for low critical energy and single source point sources, entails the insertion of a dipole in one of the newly created mid-cell straights of the machine, while reducing the bending power of the nearby gradient dipoles. After performing the linear matching of the lattice, reproducing a comparable phase advance in the modified cell, we studied the non-linear dynamics of the system. Comparison of the main observables (Dynamic Aperture, Injection Efficiency and Lifetime) with the baseline case is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB062
About •	paper received ※ 18 May 2021 paper accepted ※ 28 May 2021 issue date ※ 12 August 2021
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MOPAB065	Optimization of the Lattice Replacement Options for the Next Generation Australian Synchrotron	lattice, synchrotron, storage-ring, sextupole	269
	R. Auchettl, R.T. Dowd, Y.E. Tan AS - ANSTO, Clayton, Australia
	The design of a next generation Australian Synchrotron replacement lattice is a multi-objective and multi-constrained problem. Our group was tasked to produce a low emittance design while re-using the existing tunnel infrastructure and injector system. Our objectives coupled with the set infrastructure constraints are not straightforward to achieve with manual design. Several variables act at cross-purposes to one-another, leading to a conflicting trade-off between objectives. Recently we have investigated replacement options for the Australian Synchrotron containing longitudinal gradient and reverse bends in the form of a 4BA (4-bend achromat) lattice. In this work, optimise the lattice design for a potential fourth generation Australian Synchrotron facility. We outline the baseline 4BA solution to the lowest emittance lattice that can reuse the existing tunnels and injector system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB065
About •	paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 19 August 2021
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MOPAB066	Dual Octupole Emittance Growth Correction of the CompactLight XFEL Bunch Compressors	octupole, FEL, lattice, linac	272
	R. Auchettl, R.T. Dowd AS - ANSTO, Clayton, Australia
	An optimized CompactLight X-Ray Free Electron Laser (FEL) bunch compressor design is presented. In this work, we insert an octupole into the center of the two sequential bunch compressors. We show how this scheme can adjust the compression, while correcting the undesirable peak current profile and emittance growth.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB066
About •	paper received ※ 24 May 2021 paper accepted ※ 28 May 2021 issue date ※ 24 August 2021
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MOPAB071	Progress with the Booster Design for the Diamond-II Upgrade	booster, injection, storage-ring, extraction	286
	I.P.S. Martin, C. Christou, M.P. Cox, R.T. Fielder, J. Kallestrup, A. Shahveh, W. Tizzano DLS, Oxfordshire, United Kingdom A.D. Brynes, J.K. Jones, B.D. Muratori, H.L. Owen STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Efficient injection into the Diamond-II storage ring [, ] will require an emittance and bunch length substantially below the values produced from the existing booster. Whilst an earlier design for a replacement based on TME cells was able to meet the target values of <30 nm.rad and <40 ps respectively [, *], several technical constraints have led to a rethink of this solution. The revised booster lattice utilises a larger number of cells based on combined-function magnets with lower peak fields that still meets the emittance and bunch length goals. In addition, the new ring has been designed to have low impedance to maximise the extracted charge per shot. In this paper we describe the main features of the lattice, present the status of the engineering design and quantify the expected performance. Diamond-II Conceptual Design Report, Diamond Light Source H. Ghasem et al, these proceedings I. Martin, R. Bartolini, J.Phys.:Conf. Ser., 1067, 032005 ***I. Martin et al, IPAC 2019, WEPMP042
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB071
About •	paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 02 September 2021
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MOPAB074	Preliminary Study of Design Method for Hybrid MBA Lattice	lattice, resonance, linear-dynamics, sextupole	297
	J.J. Tan, Z.H. Bai, Z.L. Ren, J.H. Xu USTC/NSRL, Hefei, Anhui, People’s Republic of China Q. Zhang INEST, Hefei, People’s Republic of China
	Nonlinear optimization of hybrid multi-bend-achromat (HMBA) lattice is a difficult task due to its quite limited variables of multipole magnets. As a result, it is necessary to consider nonlinear potential of the lattice in its linear design. Nonlinear dynamics can be estimated by nonlinear driving terms and detuning terms. In this paper, we propose a design method for HMBA lattice. In this method, objective functions include emittance and two indicators of nonlinear dynamics, which consist of nonlinear driving terms and detuning terms. As an example, an HMBA lattice for a 2.2 GeV storage ring with circumference of 460.8 m was designed to demonstrate the method.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB074
About •	paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 21 August 2021
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MOPAB075	Proposal of the Southern Advanced Photon Source and Current Physics Design Study	photon, linac, storage-ring, lattice	300
	S. Wang, J. Chen, L. Huang, Y. Jiao, B. Li, Z.P. Li, W. Liu, S.Y. Xu IHEP, Beijing, People’s Republic of China Y. Han, X.H. Lu, Y. Zhao IHEP CSNS, Guangdong Province, People’s Republic of China X. Liu Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan
	It has been considered to build a mid-energy fourth-generation storage ring light source neighbouring the China Spallation Neutron Source, in Guangdong Province, the south of China. The light source is named the Southern Advanced Photon Source (SAPS). Preliminary physics design studies on the SAPS have been implemented for a few years. In this paper, we will describe considerations of technical roadmap and key parameter choice for this light source, and introduce the up-to-date lattice designs and related physics studies on the SAPS.
	Poster MOPAB075 [1.689 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB075
About •	paper received ※ 12 May 2021 paper accepted ※ 20 May 2021 issue date ※ 21 August 2021
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MOPAB089	Effect of Different Models of Combined-function Dipoles on the HEPS Parameters	dipole, lattice, storage-ring, quadrupole	335
	Y.Y. Guo, Y. Jiao, N. Li IHEP, Beijing, People’s Republic of China
	The high energy photon source (HEPS) is a 6 GeV, kilometer-scale storage ring light source being built in Beijing, China. In the current ring lattice, the combined-function dipoles are used and assumed to have constant dipole field. However, in the actual magnet design, an eccentrically placed quadrupole is adopted, in which the bending field along the trajectory is not constant. In this paper, we will present the effect of the two models of combined-function dipoles on the parameters of the storage ring.
	Poster MOPAB089 [0.590 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB089
About •	paper received ※ 13 May 2021 paper accepted ※ 25 May 2021 issue date ※ 27 August 2021
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MOPAB095	Concept Design for the CLS2 Accelerator Complex	electron, storage-ring, synchrotron, lattice	354
	M.J. Boland, P.J. Hunchak University of Saskatchewan, Saskatoon, Canada C.K. Baribeau, D. Bertwistle, J.M. Patel, H. Shaker, X. Shen, M.J. Sigrist CLS, Saskatoon, Saskatchewan, Canada F. Le Pimpec EuXFEL, Schenefeld, Germany E.J. Wallén LBNL, Berkeley, California, USA
	The Canadian Light Source has been in operation since 2005 and is now looking at a design concept to upgrade to a fourth generation storage ring. A brief overview is given of a possible accelerator complex layout, including some details on the lattice design and injection system. A full energy linac is being explored as an option for top-up injection and to future proof the facility for a potential FEL upgrade in the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB095
About •	paper received ※ 23 May 2021 paper accepted ※ 28 July 2021 issue date ※ 13 August 2021
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MOPAB101	Hollow and Flat Electron Beam Generation at FACET-II	electron, wakefield, quadrupole, experiment	376
	A. Halavanau, S.J. Gessner, C.E. Mayes SLAC, Menlo Park, California, USA J.B. Rosenzweig UCLA, Los Angeles, California, USA
	In this proceeding, we investigate hollow and flat electron beam generation at FACET-II facility. We focus on the case of a circular beamlet arrangement, also known as ’necklace’ beams. We study, via numerical simulations, the resulting e-beam dynamics in the FACET-II photoinjector, beam propagation through the high energy section, as well as possible experimental applications of the ’necklace’ beams. Finally, we evaluate the feasibility of high charge flat beam generation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB101
About •	paper received ※ 23 May 2021 paper accepted ※ 27 July 2021 issue date ※ 23 August 2021
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MOPAB103	Study of Transverse Oscillation Coupling and Possibility of Its Minimization in SKIF (Novosibirsk)	coupling, quadrupole, sextupole, storage-ring	383
	D. Leshenok BINP, Novosibirsk, Russia G.N. Baranov, E.B. Levichev, S.A. Nikitin BINP SB RAS, Novosibirsk, Russia
	The vertical emittance and, in general, the vertical beam size and angular divergence are of paramount importance in the SKIF (Russian acronym for Siberian Circular Photon Source) project developed in Novosibirsk. Therefore, a detailed simulation of the corresponding influence of possible errors in the storage ring was carried out with cross-validation by different methods. Variants of cross-coupling correction are proposed and modeled to obtain a vertical emittance of the order of one picometer simultaneously with minimizing vertical dispersion.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB103
About •	paper received ※ 18 May 2021 paper accepted ※ 17 August 2021 issue date ※ 19 August 2021
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MOPAB106	Enhancing the MOGA Optimization Process at ALS-U with Machine Learning	lattice, dynamic-aperture, sextupole, storage-ring	387
	Y. Lu, M.P. Ehrlichman, T. Hellert, S.C. Leemann, H. Nishimura, C. Sun, M. Venturini LBNL, Berkeley, California, USA
	Funding: This research is funded by the US Department of Energy(BES & ASCR Programs), and supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231. The bare lattice optimization for the linear and nonlinear ALS-U storage ring lattice, even without reverse bending, comprises 11 degrees of freedom (DoF) and is therefore a very complex and highly time-consuming process. This design process relies heavily on multi-objective genetic algorithms (MOGA), usually requiring many months of experienced scientists’ time. The main problem lies in having to evaluate numbers of candidate lattices due to the stochastic process of MOGA. Although almost all of these candidates are eventually rejected, they nevertheless require extensive particle tracking to arrive at a Pareto front. We therefore propose a novel Machine Learning (ML) pipeline that nonlinear tracking is replaced by two well-trained neural networks (NNs) to predict dynamic aperture (DA) and momentum aperture (MA) for any lattice candidate. Initial training of these models takes only several minutes on conventional CPUs while predictions are then rendered near instantaneously. We present this novel method and demonstrate the resulting orders of magnitude speedup of the ML-enhanced MOGA process on a 2-DoF problem as well as first results on a more complex 11-DoF problem.
	Poster MOPAB106 [0.918 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB106
About •	paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 18 August 2021
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MOPAB109	A Lattice for PETRA IV Based on the Combination of Different Arc Cell Designs	lattice, undulator, sextupole, resonance	399
	J. Keil, I.V. Agapov, R. Brinkmann DESY, Hamburg, Germany
	The 6 GeV synchrotron light source PETRA III at DESY is in user operation since 2009. In 2016 investigations of upgrading PETRA III into a diffraction limited storage ring at 10 keV have been started. The ambitious goal is to achieve an emittance in the range of 10-30 pm*rad. For the conceptual design report (CDR) of PETRA IV a lattice based on hybrid multi-bend achromats (HMBA) has been chosen. It consists of eight arcs connected by eight long straight sections whereas each arc consists of eight HMBA cells. While this lattice variant has an advantage in terms of simplicity of magnet and girder design it is challenging in regards of multipole strengths and beam dynamic properties. However, only a part of all eight arcs will be used for undulator beamlines. This offers the possibility to choose a more relaxed optics design in the arcs without undulators while preserving the ultra-low emittance. In addition, the use of reverse bends in the undulator cells allows smaller beta functions at the undulators for an increased brilliance. The design and the beam dynamic properties of this combi lattice are discussed in this paper and compared to the lattice based on HMBA cells.
	Poster MOPAB109 [1.338 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB109
About •	paper received ※ 18 May 2021 paper accepted ※ 28 May 2021 issue date ※ 30 August 2021
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MOPAB110	An Electron Synchrotron Lattice Based on Theoretic Minimal Emittance Cell	lattice, extraction, sextupole, synchrotron	403
	H.C. Chao DESY, Hamburg, Germany
	A design of an electron synchrotron featuring the theoretic minimal emittance (TME) cells is presented. It has 32 superperiods and the circumference is around 300 m. It offers versatile functions with the equilibrium emittance less than 10 nm-rad at 6 GeV. The beam energy can go up to 7 GeV. Locations with proper phase advances are found to form effective vertical orbit bumps, which can be used for the injections and extraction. A tune scan study shows the sweet spot for the working point. Some discussions of other usages and studies of synchro-betatron coupling effects are also included in this article.
	Poster MOPAB110 [0.777 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB110
About •	paper received ※ 11 May 2021 paper accepted ※ 28 May 2021 issue date ※ 30 August 2021
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MOPAB112	A Modified Hybrid 6BA Lattice for the HALF Storage Ring	lattice, damping, storage-ring, SRF	407
	Z.H. Bai, G.Y. Feng, T.L. He, W. Li, W.W. Li, G. Liu, Z.L. Ren, L. Wang, P.H. Yang, S.C. Zhang, T. Zhang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	In this paper, we propose a modified hybrid 6BA lattice as the baseline lattice of the Hefei Advanced Light Facility (HALF) storage ring. Similar to the Diamond-II lattice, the proposed lattice cell has one long straight section and one mid-straight section; but the two bend units adjacent to the mid-straight are LGB/RB units (LGB: longitudinal gradient bend, RB: reverse bend), which can give both lower emittance and shorter damping times. The designed HALF storage ring, with an energy of 2.2 GeV and 20 lattice cells, has a natural emittance of about 85 pm·rad.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB112
About •	paper received ※ 15 May 2021 paper accepted ※ 20 May 2021 issue date ※ 01 September 2021
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MOPAB113	A Low-emittance Booster Lattice Design for the SOLEIL Upgrade	booster, lattice, storage-ring, linear-dynamics	410
	M.-A. Tordeux, A. Loulergue, R. Nagaoka SOLEIL, Gif-sur-Yvette, France Z.H. Bai, G. Liu, T. Zhang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	The SOLEIL storage ring upgrade will require an injected beam with small transverse and longitudinal sizes. To meet this requirement, the present booster also needs to be upgraded, aiming to reduce the emittance below 10 nm·rad. A multi-bend achromat lattice is designed in this context for the booster upgrade, which consists of two superperiods to respect the present race-track configuration. The lattice is a 16BA HOA (Higher-Order Achromat) type lattice, composed of 14 unit cells, 2 matching cells and a long straight section, and combined-function bending magnets are used in the unit cells to both save space and reduce the emittance. The natural emittance of the designed booster is 5.2 nm·rad at the final energy of 2.75 GeV. This paper presents the general constraints, linear lattice design and nonlinear dynamics optimization for the booster upgrade.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB113
About •	paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 26 August 2021
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MOPAB119	Comparisons Between AT and Elegant Tracking	lattice, closed-orbit, simulation, dynamic-aperture	432
	G. Penn, T. Hellert, M. Venturini LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DEAC02-05CH11231. The simulation codes Elegant* and Accelerator Toolbox (AT)** are both in common use for the study of particle accelerators and light sources. They use different software platforms and have different capabilities, so there is a strong motivation to be able to switch from one version to another to achieve different goals. In addition, it is useful to directly compare results for benchmarking studies. We discuss differences in tracking methods and results for various elements, and explore the impact on simulations performed with lattices designed for the ALS-U. In addition to single-particle tracking, global properties such as chromaticity, dynamics aperture, momentum aperture and beam lifetime are also investigated. We have also developed scripts to translate AT lattices into elegant lattice files to facilitate comparisons. * M. Borland, Advanced Photon Source LS-287, September 2000. ** A. Terebilo, Particle Accelerators Conference 2001, p. 3203.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB119
About •	paper received ※ 20 May 2021 paper accepted ※ 31 May 2021 issue date ※ 30 August 2021
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MOPAB126	BESSY III & MLS II - Status of the Development of the New Photon Science Facility in Berlin	undulator, radiation, lattice, photon	451
	P. Goslawski, M. Abo-Bakr, F. Andreas, M. Arlandoo, J. Bengtsson, V. Dürr, K. Holldack, J.-G. Hwang, A. Jankowiak, B.C. Kuske, J. Li, A.N. Matveenko, T. Mertens, A. Meseck, E.C.M. Rial, M. Ries, M.K. Sauerborn, A. Schälicke, M. Scheer, P. Schnizer, L. Shi, J. Viefhaus HZB, Berlin, Germany J. Lüning UPMC, Paris, France
	HZB operates and develops two synchrotron radiation sources at Berlin Adlershof. The larger one, BESSY II with an energy of 1.7 GeV and 240 m circumference is optimized for soft-X rays and in operation since 1999. The smaller one is the MLS (Metrology Light Source), owned by the Physikalische Technische Bundesanstalt (PTB) - Germany’s National Metrology Institute. It is designed to fulfill the special metrology needs of the PTB with an energy of 0.6 GeV and 48 m circumference, covering the spectral range from THz and IR to EUV/VUV. In 2020 a discussion process has been started to define the requirements for successors of BESSY II and MLS and to study the possibilities integrate them into a new photon science facility in Berlin Adlershof. Here, we give a status report and present a first envisaged parameter space to both machines (see also MOPAB262, MOPAB220, MOPAB048, MOPAB242).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB126
About •	paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 18 August 2021
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MOPAB131	Synchrotron SOLEIL Upgrade Project	lattice, photon, vacuum, injection	463
	A. Nadji SOLEIL, Gif-sur-Yvette, France
	To remain competitive in the future, SOLEIL is also working on an upgrade project plan based on Multi-Bend Achromat (MBA) lattices. The Technical Design Report of the project is expected to start in early 2021 immediately after the completion of the Conceptual Design Report (CDR) phase. The achieved equilibrium emittance in the CDR reference lattice (80 pm-rad) is about 50 times smaller than that of the existing storage ring (4000 pm-rad). By operating on a linear coupling resonance, round beam sizes in Insertion Devices straight sections of less than 10 microns RMS in both planes can be produced. These performances rely on the use of a 10 mm inner diameter circular copper vacuum chamber with NEG-coating allowing reaching strong quadrupole gradients and very strong sextupole and octupole strengths. As all these technical challenges are pushing the engineering technology to the limits, they are being investigated through an intensive R&D program based on extensive numerical simulations, prototyping, and measurement with the beam. Extensive use of the pure permanent magnet technology beyond what has been done so far in the other similar projects is considered in this project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB131
About •	paper received ※ 22 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021
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MOPAB133	Recovering the Positron Beam After Muon Production in the Lemma Muon Source	target, positron, linac, injection	470
	I. Drebot INFN-Milano, Milano, Italy M.E. Biagini, O.R. Blanco-García, A. Giribono, S. Guiducci, C. Vaccarezza, A. Variola INFN/LNF, Frascati, Italy S.M. Liuzzo ESRF, Grenoble, France
	In the LEMMA muon source proposal* a positron beam at 45 GeV is used to produce muons at threshold by interaction with some targets. In order to release the required intensity on the main positron source, orders of magnitude higher than the state of the art, the possibility to recover the primary positron beam after the interaction with the targets was studied. The particles distribution, with a strongly degraded energy spread after the interac- tion, was injected back into a low emittance, large energy acceptance 45 GeV ring. Studies of injection efficiency were performed. The possibility of compressing the beam in a linac before injection was also studied. As a result, even without compression, about 80% of the disrupted e⁺ beam can be injected back into the ring. * D. Alesini et al, "Positron driven muon source for a muon collider", arXiv:1905.05747v2 [physics.acc-ph], May 2019
	Poster MOPAB133 [4.171 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB133
About •	paper received ※ 17 May 2021 paper accepted ※ 24 May 2021 issue date ※ 20 August 2021
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MOPAB134	Normalized Transverse Emittance Reduction via Ionization Cooling in MICE ’Flip Mode’	simulation, solenoid, experiment, betatron	474
	P.B. Jurj Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	Low emittance muon beams are central to the development of a Muon Collider and can significantly enhance the performance of a Neutrino Factory. The international Muon Ionization Cooling Experiment (MICE) has recorded several million individual muon tracks passing through a liquid hydrogen or a lithium hydride absorber and has demonstrated the ionization cooling of muon beams. Previous analysis used a restricted data set, and the beam matching was not perfect. In this analysis, beam sampling routines were employed to account for imperfections in beam matching at the entrance into the cooling channel and enable an improvement of the cooling measurement. A study of the normalized transverse emittance change in the MICE cooling channel set up in a flipped polarity magnetic field configuration is presented. Additionally, the evolution of the canonical angular momentum across the absorber is shown and the characteristics of the cooling effect are discussed.
	Poster MOPAB134 [1.821 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB134
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021
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MOPAB149	Ion Motion in Flat Beam Plasma Accelerators	plasma, electron, collider, linear-collider	521
	M. Yadav, C.E. Hansel, J.B. Rosenzweig UCLA, Los Angeles, California, USA O. Apsimon, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom O. Apsimon, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work was supported by UCLA and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1. This work is done on SCARF Cluster. Intense beams, such as those in proposed plasma based linear colliders, can not only blow out electrons to form a bubble but can also attract ions towards the beam. This violates the assumption that the ions are stationary on the timescale of the beam, which is a common assumption for shorter and less intense beams. While some research has been done on understanding the physics of ion motion in blowout Plasma Wakefield Accelerators (PWFAs), this research has almost exclusively focused on cylindrically symmetric beams, rather than flat asymmetric emittance beams which are often used in linear colliders in order to minimize beamstrahlung at the final focus. This contribution investigates both analytically and computationally ion motion of a flat beam scenario in order to understand the basic physics as well as how to mitigate emittance growth, beam hosing and quadrupole.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB149
About •	paper received ※ 24 May 2021 paper accepted ※ 17 June 2021 issue date ※ 11 August 2021
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MOPAB153	Laser Microfabrication for Accelerator Applications	laser, FEM, simulation, cathode	535
	S.P. Antipov, S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Laser microfabrication allows high precision ablation of materials at sub-mm scale. When laser pulse length is shorter than about 10 picoseconds the heat affected zone is minimized and ablation occurs without melting. Work-pieces processed in this fashion exhibit less structural damage and are expected to have a higher damage thresholds. In this paper we will review several case studies of laser-microfabricated components for accelerator and x-ray applications. Ablated materials include diamond, quartz, tungsten, copper, YAG:Ce and silicon.
	Poster MOPAB153 [2.781 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB153
About •	paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 29 August 2021
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MOPAB191	Method Development for Cavity Failure Compensation in a Superconducting Linac	cavity, linac, lattice, ECR	647
	F. Bouly LPSC, Grenoble Cedex, France
	Reliability is a major challenge within the perspective of improving the performances and sustainability of MegaWatt class accelerators. To optimize the operational costs of such accelerators the availability requirements are becoming more and more challenging. These requirements are even more stringent in the case of Accelerator Driven systems (ADS). As an example, for the MYRRHA (Multipurpose Hybrid Research Reactor for High-tech Applications) ADS demonstrator, the actual availability limit is set to a maximum of 10 beam interruptions (longer than 3 seconds) over a 3-month operating cycle. For this purpose, the accelerator design is based on a redundant and fault-tolerant scheme to enable rapid mitigation of a cavity failure. The adopted strategy is to apply for local compensation: a failed cavity is compensated by several neighboring cavities. Beam dynamics studies and method developments to apply such a failure compensation scheme are here reviewed. First simulation results for superconducting linac retuning and potential future improvements will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB191
About •	paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 20 August 2021
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MOPAB200	Parameters Measurements of Proton Beam Extracted from CSNS/RCS	target, MMI, neutron, extraction	668
	Z.P. Li, Y.W. An, M.Y. Huang IHEP, Beijing, People’s Republic of China Y. Li, S.Y. Xu DNSC, Dongguan, People’s Republic of China H.Y. Liu IHEP CSNS, Guangdong Province, People’s Republic of China
	In order to study the emittance evolution of the circulating beam in the fast-cycling synchrotron (RCS) of the Chinese Spallation Neutron Source (CSNS), parameter measurements of the beam extracted at different times were carried out. The measurements were mainly based on wire-scanners mounted in RCS to target transport line (RTBT) for beam profile measurement, and different methods were applied in the solution processes. The emittance and C.S parameters of the extracted beam at different times were obtained and studied, which provided an important reference basis for the beam commissioning of RCS. The beam envelope along the RTBT has been matched and re-measured, which was in good agreement with the design optics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB200
About •	paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 25 August 2021
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MOPAB205	Minerva (MYRRHA Phase 1) RFQ Beam Commissioning	rfq, LEBT, MMI, linac	675
	A. Gatera, J. Belmans, F. Davin, W. De Cock, F. Doucet, L. Parez, F. Pompon, A. Ponton, D. Vandeplassche SCK•CEN, Mol, Belgium F. Bouly LPSC, Grenoble Cedex, France C. Joly, L. Perrot Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France H. Podlech IAP, Frankfurt am Main, Germany J. Tamura JAEA/J-PARC, Tokai-mura, Japan C. Zhang GSI, Darmstadt, Germany
	Funding: Part of this work was supported by the European Commission Framework Programme H₂020, MYRTE project nr. 662186 The MYRRHA project aims at coupling a 600 MeV proton accelerator to a subcritical fission core operating at a thermal power of 60 MW. The nominal proton beam for this ADS has an intensity of 4 mA and is delivered in a quasi-CW mode. Phase 1 of the project will realize a 100 MeV, 4 mA superconducting linac with the mission of ensuring the ADS requirements in terms of reliability and fault tolerance. As part of the reliability optimization program the integrated prototyping of the MINERVA injector is ongoing. The front-end of the injector is composed of an ECR proton source, a 2.6 m long LEBT (low energy beam transport line) and a four-rod RFQ accelerating the beam to 1.5 MeV. The present contribution focuses on the current beam tests on the RFQ, including beam matching, RF conditioning, assessment of the cavities’ performances and accelerated beam characterisation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB205
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 24 August 2021
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MOPAB207	Design Guideline for Minimizing Space-Charge-Induced Emittance Growth	rfq, proton, space-charge, linac	682
	C. Zhang GSI, Darmstadt, Germany
	Space-charge-induced emittance growth is a big concern for designing low-energy and high-intensity linacs. The Equipartitioning Principle was introduced to minimize space-charge-induced emittance growth by removing free energy between the transverse and longitudinal degrees of freedom. In this study, a different design guideline is being proposed. It suggests holding the ratio of longitudinal emittance to transverse emittance around one and take advantage of low emittance transfer for minimizing emittance growth. Using a high-intensity RFQ accelerator as an example, a comparison between the two design methods has been made.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB207
About •	paper received ※ 17 May 2021 paper accepted ※ 21 May 2021 issue date ※ 01 September 2021
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MOPAB212	3-D Quantum Lifetime	simulation, electron, damping, radiation	700
	H. Zhao, M. Blaskiewicz BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The quantum lifetime of electron beam in storage rings is defined by the particle loss that caused by the aperture limitation. Based on the equilibrium beam distribution produced by radiation damping and quantum excitation, the 1-d quantum lifetime has been well studied by A. Piwinski. In this paper, we give the derivation of the 3-d quantum lifetime, which can be applied to the machines with elliptical aperture and momentum acceptance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB212
About •	paper received ※ 04 June 2021 paper accepted ※ 21 June 2021 issue date ※ 16 August 2021
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MOPAB216	20-24 GeV FFA CEBAF Energy Upgrade	linac, booster, lattice, optics	715
	S.A. Bogacz, J.F. Benesch, R.M. Bodenstein, B.R. Gamage, G.A. Krafft, V.S. Morozov, Y. Roblin JLab, Newport News, Virginia, USA J.S. Berg, S.J. Brooks, D. Trbojevic BNL, Upton, New York, USA D. Douglas Douglas Consulting, York, Virginia, USA G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 A proposal was formulated to increase the CEBAF energy from the present 12 GeV to 20-24 GeV by replacing the highest-energy arcs with Fixed Field Alternating Gradient (FFA) arcs. The new pair of arcs would provide six or seven new beam passes, going through this magnet array, allowing the energy to be nearly doubled using the existing CEBAF SRF cavity system. One of the immediate accelerator design tasks is to develop a proof-of-principle FFA arc magnet lattice that would support simultaneous transport of 6-7 passes with energies spanning a factor of two. We also examine the possibility of using combined function magnets to configure a cascade, six-way beam split switchyard. Finally, a novel multi-pass linac optics based on a weakly focusing lattice is being explored.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB216
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 29 August 2021
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MOPAB220	Towards Deterministic Design of MBA-Lattices	dipole, lattice, quadrupole, sextupole	722
	B.C. Kuske HZB, Berlin, Germany
	Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of the Helmholtz Association Since the pioneering work of MAX IV , multi-bend achromat (MBA) lattices have become the standard in lattice design for 4th generation lights sources as well as upgrades of 3rd generation storage rings. The distribution of the bending angle to many weak dipoles enables to reach unprecedented low emittance and highest brightness. In their most basic form, MBA-lattices consist of a repetitive unit cell and two identical matching cells on either end of the achromatic arc. The simplicity of both cells allows for a unique determination of the linear lattice parameters in dependence on boundary conditions defined by the design goals. Those might be the emittance, momentum compaction factor, chromaticity, as well as phase advances with respect to achieving higher-order achromatic structures. A scan of optional lattice prototypes is quickly obtained. We demonstrate this concept and apply it in the design of the first candidates for the lattice of BESSY III, a green-field 4th generation storage ring being currently planned at HZB, Berlin, Germany. https://www.maxiv.lu.se/accelerators-beamlines/accelerators/accelerator-documentation/max-iv-ddr/
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB220
About •	paper received ※ 17 May 2021 paper accepted ※ 23 July 2021 issue date ※ 26 August 2021
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MOPAB225	A HMBA Lattice Design Study for the 4 GeV Light Source	lattice, storage-ring, dipole, sextupole	734
	S.W. Jang, E.-S. Kim KUS, Sejong, Republic of Korea
	The 4th generation storage ring (4GSR) project will start from 2022 in South Korea. We proposed HMBA (Hybrid Multi-Bend Achromatic) lattice for 4GSR with super-bend at the center of the lattice. The 4GSR lattice is designed to combined HMBA lattice with a 4 GeV, 53 pm-rad emittance and 843m. The storage ring including 32 long with 5.65m, 16 short straight with 1.3m sections for IDs and 16 super-bend sections for more different type of beam line experiments. A calculated dynamic aperture is more larger than 15mm in both direction and the beam life time is expected to 4.7 hour. In this paper, we will describe the study results of the HMBA lattice design with a 4GeV light source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB225
About •	paper received ※ 20 May 2021 paper accepted ※ 24 May 2021 issue date ※ 30 August 2021
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MOPAB235	Transverse 2d Phase-Space Tomography Using Beam Position Monitor Data of Kicked Beams	optics, electron, betatron, storage-ring	763
	K. Hwang, C.E. Mitchell, R.D. Ryne LBNL, Berkeley, California, USA
	Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231 The time-series Beam Position Monitor (BPM) data of kicked beam is a function of lattice parameters and beam parameters including phase-space density. The decoherence model using the first-order detuning parameter has an exact solution when the beam is Gaussian. We parameterize the beam phase-space density by multiple Gaussian kernels of different weights, means, and sizes to formulate the inverse problem for 2D phase-space tomography. Numerical optimization and Bayesian inference are used to infer the beam density.
	Poster MOPAB235 [1.253 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB235
About •	paper received ※ 20 May 2021 paper accepted ※ 02 June 2021 issue date ※ 01 September 2021
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MOPAB236	Ion Beam Dynamics in Linac-100 Facility at Jinr	linac, cavity, acceleration, rfq	767
	S.M. Polozov, V.S. Dyubkov, Y. Lozeev, T.A. Lozeeva, A.V. Samoshin MEPhI, Moscow, Russia
	The heavy-ion linac LINAC-100 is a superconducting driver-accelerator proposed as one of the prospective projects at JINR. Its goal is to accelerate primary stable isotope CW high-intensity beams to energies up to 100 MeV/u. This linac is discussed as the first stage of a new rare isotope facility DERICA (Dubna Electron-Radioactive Ion Collider fAcility), being under development at JINR since 2017. LINAC-100 is supposed to work with a wide range of beams with A/Z 3.5/7, Uranium U³⁴⁺ being the heaviest. Its concept has undergone many changes, mostly considering stripping cells to increase accelerator efficiency. During the latest investigations of various stripping cells [, *], Uranium beam stripping at the energy 10 MeV/u and utilizing three adjacent charge states 59-61+ resulted in 60% output beam intensity preservation (or 30 pA overall output current). The current layout of the LINAC-100 is the following: one or two (separately for light and heavy ions) normal conducting front-end linacs, gas stripper cell at 10 MeV/u, and the SC section. In this paper three charge state Uranium beam dynamics in the current version of SC LINAC-100 section is presented. S Polozov 2020 PhysScr 95 084006 A S Fomichev Phys Usp 62(7) 675-690 2019 Tolstikhina I 2018 Basic At Int of Acc H Ions in Matter 98 1 *** W Barth J Phys Conf Ser 1350:012096
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB236
About •	paper received ※ 20 May 2021 paper accepted ※ 17 August 2021 issue date ※ 26 August 2021
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MOPAB240	Estimates of Damped Equilibrium Energy Spread and Emittance in a Dual Energy Storage Ring	storage-ring, damping, photon, radiation	774
	B. Dhital, G.A. Krafft ODU, Norfolk, Virginia, USA Y.S. Derbenev, D. Douglas, A. Hutton, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177 and DE-AC02-06CH11357. / Jefferson Lab EIC Fellowship2020. A dual energy storage ring design consists of two loops at markedly different energies. As in a single-energy storage ring, the linear optics in the ring design may be used to determine the damped equilibrium emittance and energy spread. Because the individual radiation events in the two rings are different and independent, we can provide analytical estimates of the damping times in a dual energy storage ring. Using the damping times, the values of damped energy spread, and emittance can be determined for a range of parameters related to lattice design and rings energies. We present analytical calculations along with simulation results to estimate the values of damped energy spread and emittance in a dual energy storage ring. We note that the damping time tends to be dominated by the damping time of the high energy ring in cases where the energy of the high energy rings is significantly greater than that of the low energy ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB240
About •	paper received ※ 17 May 2021 paper accepted ※ 27 May 2021 issue date ※ 13 August 2021
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MOPAB242	A Six-Bend-Achromat Lattice for a 2.5 GeV Diffraction-Limited Storage Ring	lattice, quadrupole, storage-ring, dipole	782
	J. Li, M. Abo-Bakr, P. Goslawski HZB, Berlin, Germany Z.H. Bai USTC/NSRL, Hefei, Anhui, People’s Republic of China
	HZB has proposed a 2.5 GeV diffraction-limited storage ring as the upgrade of BESSY II. A Six-Bend-Achromat lattice based on Higher-Order Achromat, as one of the possible solutions, has been designed to meet the requirements of low emittance, compact layout, large dynamic aperture and large momentum acceptance. The linear lattice design and the nonlinear performance are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB242
About •	paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 17 August 2021
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MOPAB245	Theoretical Analysis of the Conditions for an Isochronous and CSR-Immune Triple-Bend Achromat with Stable Optics	dipole, optics, radiation, synchrotron-radiation	786
	C. Zhang, Y. Jiao IHEP, Beijing, People’s Republic of China C.-Y. Tsai HUST, Wuhan, People’s Republic of China
	Funding: National Natural Science Foundation of China (No. 11922512), Youth Innovation Promotion Association of Chinese Academy of Sciences (No. Y201904), National Key R&D Program of China (No. 2016YFA0401900) Transport of high-brightness beams with minimum degradation of the phase space quality is pursued in modern accelerators. For the beam transfer line which commonly consists of bending magnets, it would be desirable if the transfer line can be isochronous and coherent synchrotron radiation (CSR)-immune. For multi-pass transfer line, the achromatic cell designs with stable optics would bring great convenience. In this paper, based on the transfer matrix formalism and the CSR point-kick model, we report the detailed theoretical analysis and derive the condition for a triple-bend achromat with stable optics in which the first-order longitudinal dispersion (i.e., R56) and the CSR-induced emittance growth can be eliminated. The derived condition suggests a new way of designing the bending magnet beamline that can be applied to the free-electron laser (FEL) spreader and energy recovery linac (ERL) recirculation loop.
	Poster MOPAB245 [0.530 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB245
About •	paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 27 August 2021
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MOPAB246	Design of the MEBT for the JAEA-ADS Project	MEBT, linac, rfq, quadrupole	790
	B. Yee-Rendón, Y. Kondo, F.M. Maekawa, S.I. Meigo, J. Tamura JAEA/J-PARC, Tokai-mura, Japan
	The Medium Energy Beam Transport (MEBT) will transport a CW proton beam with a current of 20 mA and energy of 2.5 MeV from the exit of the normal conducting Radiofrequency Quadrupole (RFQ) to the superconducting Half-Wave resonator (HWR) section. The MEBT must provide a good matching between the RFQ and HWR, effective control of the emittance growth and the halo formation, enough space for all the beam diagnostics devices, among others. This work reports the first lattice design and the beam dynamics studies for the MEBT of the JAEA-ADS.
	Poster MOPAB246 [0.827 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB246
About •	paper received ※ 10 May 2021 paper accepted ※ 02 June 2021 issue date ※ 19 August 2021
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MOPAB257	Effects of Mode Launcher on Beam Dynamics in Next Generation High Brightness C-Band Guns	gun, simulation, electron, cathode	813
	A. Giribono, D. Alesini, F. Cardelli, G. Di Raddo, M. Ferrario, A. Gallo, J. Scifo, C. Vaccarezza, A. Vannozzi INFN/LNF, Frascati (Roma), Italy G. Castorina AVO-ADAM, Meyrin, Switzerland L. Ficcadenti INFN-Roma, Roma, Italy G. Muti Sapienza University of Rome, Rome, Italy G. Pedrocchi SBAI, Roma, Italy
	High-brightness RF photo-injectors plays nowadays a crucial role in the fields of radiation generation and advanced acceleration schemes. A high gradient C-band photoinjector consisting of a 2.5 cell gun followed by TW sections is here proposed as an electron source for radiation user facilities. The paper reports on beam dynamics studies in the RF injector and illustrates the effects on the beam quality of the mode launcher with a focus on the compensation of the quadrupole RF components.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB257
About •	paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 16 August 2021
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MOPAB262	First Thoughts on Lattices for a possible Metrology Light Source 2	lattice, dipole, sextupole, radiation	833
	M. Arlandoo, M. Abo-Bakr, P. Goslawski, J. Li HZB, Berlin, Germany
	The Physikalisch-Technische Bundesanstalt (PTB), in cooperation with the Helmholtz-Zentrum Berlin (HZB), operates the Metrology Light Source (MLS), which is a low-energy electron storage ring. The MLS can be operated in a low-alpha mode to produce coherent synchroton ration in the far-IR and THz spectral range. In the scope of the Conceptual Design process for a BESSY II successor, the PTB also requested for an MLS successor to cover their increasing demands on synchrotron radiation. A combination of two different machines, one optimized for low emittance (BESSY III) and one for flexible timing capabilities (MLS II), would provide best radiation capabilities for our user community. In this paper, we discuss the demands on the MLS II and propose first lattice candidates which may meet the needs of the PTB and HZB. Currently, we focus on linear lattices for standard user mode with first steps towards nonlinear optimization.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB262
About •	paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 17 August 2021
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MOPAB264	Commissioning of the DESIR High-Resolution Separator at CENBG	multipole, MMI, dipole, quadrupole	841
	J. Michaud, P. Alfaurt, A. Balana, B. Blank, L. Daudin, T. Kurtukian-Nieto, S. Leblanc, L.S. Serani CENBG, Gradignan, France F. Méot BNL, Upton, New York, USA F. Varenne GANIL, Caen, France
	DESIR is the low-energy part of the SPIRAL2 ISOL facility under construction at GANIL. The high-resolution mass separator (HRS) included in DESIR is a 180 degree symmetric online separator with two 90 degree magnetic dipole sections arranged with electrostatic quadrupoles, sextupoles and a multipole on the mid plane. The HRS is now completely mounted at CENBG and under commissioning for the next 2 to 3 years before its transfer at the entrance of the DESIR facility. The objective is to test, characterise and correct all HRS elements contributing to the higher order aberration by performing experimental measurements and comparing them with the results from different simulation tools. The recently mounted pepperpot-type emittance-meter will allow us to observe the emittance figures and dynamically tune the multipole to improve the optical parameters of the HRS. We will present the first results concerning the hexapolar correction with the multipole, the associated emittance measurements and the resolution currently achieved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB264
About •	paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 10 August 2021
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MOPAB268	Design of a Continuous Wave Heavy Ion RFQ for BISOL	rfq, ISOL, LEBT, linac	851
	S. Liu, M.Y. Han, Y.R. Lu, Q.Y. Tan, Z. Wang PKU, Beijing, People’s Republic of China
	The Beijing isotope separation online (BISOL) facility will be used to study the new physics and technologies at the limit of the nuclear stability. The post accelerator for BISOL facility aims to accelerate radioactive beams to 150MeV/u. As an injector for the downstream superconducting linac, a 4-vane RFQ operating at 81.25MHz is needed to accelerate high-charge-state ions such as 132Sn²²⁺ from 3keV/u to 500keV/u in CW mode. We have compared two kinds of beam dynamics of BISOL RFQ with and without a Multi-Harmonic Buncher (MHB) bunching the continuous wave beam up-stream of the RFQ. The results indicate that it is possible to keep transverse emittance growth within tolerable limits while the longitudinal emittance is much smaller than the design without an external buncher. The acceleration of multi-charge beams simultaneously in the RFQ is also discussed in this paper.
	Poster MOPAB268 [1.829 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB268
About •	paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 16 August 2021
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MOPAB270	Beam Dynamics Studies in a Standing Wave Ka-band Linearizer	electron, bunching, operation, simulation	857
	J. Scifo, M. Behtouei, L. Faillace, M. Ferrario, A. Giribono, B. Spataro, C. Vaccarezza INFN/LNF, Frascati, Italy M. Migliorati INFN-Roma1, Rome, Italy M. Migliorati Sapienza University of Rome, Rome, Italy G. Torrisi INFN/LNS, Catania, Italy
	Next-generation FEL user facilities require high-quality electron beams with kA peak current. The combination of a high brightness RF injector and a magnetic compression stage represents a very performant solution in terms of electron beam emittance and peak current. One of the important issues is the design of a proper device that acts as a linearizer for the beam longitudinal phase space. Recently, the design of a SW Ka band RF accelerating structure has been proposed with promising results. The paper reports on electron beam dynamics studies in the described RF structure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB270
About •	paper received ※ 19 May 2021 paper accepted ※ 29 August 2021 issue date ※ 26 August 2021
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MOPAB277	Installation, Use and Follow-Up of an Emittance-Meter at the Arronax Cyclotron 70XP	cyclotron, injection, quadrupole, ECR	877
	F. Poirier, R. Bellamy, F. Bulteau-Harel, C. Castel, T. Durand, X. Goiziou, F. Haddad, C. Koumeir, R. Lelièvre, G. Mechin, L. Perrigaud, J. Poudevigne, H. Trichet Cyclotron ARRONAX, Saint-Herblain, France T. Adam, P.G. Graehling, M. Heine, C. Maazouzi, F.R. Osswald, E.K. Traykov IPHC, Strasbourg Cedex 2, France A. Dinkov, S. Wurth IJCLab, ORSAY, France F. Haddad SUBATECH, Nantes, France
	Funding: This work is supported by grants from the ANR program "Investissements d’Avenir", n°ANR-11-EQPX-0004, n°ANR-11-LABX-18-01 and n°ANR-16-IDE-0007 and by a PhD scholarship from CNRS/IN2P3. The 70 MeV cyclotron group of the Arronax GIP (Interest Public Group), France, foresees to increase its beam intensity on target. For this, several beam studies are being performed in the various sections of the accelerator including the injection. Thus, an Allison-type emittance-meter has been installed in this section above the cyclotron and downstream a quadrupole triplet. Installation and the first results of a campaign of measurements are presented including high intensity runs, up to 1 mA for 40 keV H⁻ ions. The emittance-meter is expected to be used with several accelerators throughout the world. Therefore, a strategy on the follow-up of the activation of sample materials used in the equipment is being established and is described in the paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB277
About •	paper received ※ 17 May 2021 paper accepted ※ 27 May 2021 issue date ※ 12 August 2021
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MOPAB289	Machine Learning Training for HOM reduction and Emittance Preservation in a TESLA-type Cryomodule at FAST	HOM, cavity, electron, controls	916
	J.A. Diaz Cruz UNM-ECE, Albuquerque, USA J.A. Diaz Cruz, A.L. Edelen, B.T. Jacobson, J.P. Sikora SLAC, Menlo Park, California, USA D.R. Edstrom, A.H. Lumpkin, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA
	Low emittance electron beams are of high importance at facilities like the LCLS-II at SLAC. Emittance dilution effects due to off-axis beam transport for a TESLA-type cryomodule (CM) have been shown at the Fermilab Accelerator Science and Technology facility. The results showed the correlation between the electron beam-induced cavity high-order modes (HOMs) and submacropulse centroid slewing and oscillation downstream of the CM. Mitigation of emittance dilution can be achieved by reducing the HOM signals and the variances in the submacropulse beam positions downstream of the CM. Here we present a Machine Learning based optimization and model construction for HOM signal level reduction using Neural Networks and Gaussian Processes. To gather training data we performed experiments using single bunch and 50 bunch electron beams with charges up to 125 pC/b. We measured HOM signals of all cavities and beam position with a set of BPMs downstream of the CM. The beam trajectory was changed using V/H125 corrector set located upstream of the CM. The results presented here will inform the LCLS-II injector commissioning and will serve as a prototype for HOM reduction and emittance preservation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB289
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 14 August 2021
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MOPAB295	Simulation Study of Emittance Measurement Using a Genetic Algorithm for Space Charge Dominated Beams	quadrupole, space-charge, simulation, lattice	935
	H.D. Zhang, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom
	Funding: This work was supported by the HL-LHC-UK phase II project funded by STFC under Grant Ref: ST/T001925/1 under and the STFC Cockcroft core grant No. ST/G008248/1. The quadrupole scan method is one of the traditional ways to measure beam emittance in an accelerator. The required devices are simple: several quadrupole magnets and a beam profile monitor. Beam sizes are measured from the beam profile monitor with different quadrupole settings to bring the beam through its waist and then fitted to a quadratic equation to determine the Twiss parameters. measured data from a quadrupole scan taking the beam through its waist is fitted to a quadratic equation and this allows determining the Twiss parameters. However, with increasing beam intensity, the transfer function becomes non-linear and this causes a deviation of the fitted emittance from its real value, making it no longer useful. In this contribution, a genetic algorithm is applied to find the optimum quadrupole scan fit in space-charge dominated electron beams. Results from simulations using different space charge levels are presented and scenarios identified where this method can be applied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB295
About •	paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 02 September 2021
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MOPAB303	Design of the X-Ray Beam Size Monitor for the Advanced Photon Source Upgrade	electron, photon, detector, storage-ring	956
	K.P. Wootton, F.K. Anthony, K. Belcher, J.S. Budz, J. Carwardine, W.X. Cheng, S. Chitra, G. Decker, S.J. Izzo, S.H. Lee, J. Lenner, Z. Liu, P. McNamara, H.V. Nguyen, F.S. Rafael, C. Roehrig, J. Runchey, N. Sereno, G. Shen, J.B. Stevens, B.X. Yang ANL, Lemont, Illinois, USA
	Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. A beam size monitor provides an intuitive display of the status of the beam profile and motion in an accelerator. In the present work, we outline the design of the X-ray electron beam size monitor for the Advanced Photon Source Upgrade. Components and anticipated performance characteristics of the beam size monitor are outlined.
	Poster MOPAB303 [0.577 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB303
About •	paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021
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MOPAB304	Beam Diagnostics for Multi-Objective Bayesian Optimization at the Argonne Wakefield Accelerator Facility	diagnostics, dipole, quadrupole, wakefield	960
	J.P. Gonzalez-Aguilera, Y.K. Kim University of Chicago, Chicago, Illinois, USA W. Liu, P. Piot, J.G. Power, E.E. Wisniewski ANL, Lemont, Illinois, USA R.J. Roussel Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
	Particle accelerators must achieve certain beam quality objectives for use in different experiments. Usually, optimizing certain beam objectives comes at the expense of others. Additionally, there are many input parameters and a limited number of diagnostics. Therefore, accelerator tuning becomes a multi-objective optimization problem with a limited number of observations. Multi-objective Bayesian optimization was recently proposed as an efficient method to find the Pareto front for an online accelerator tuning problem with reduced number of observations. In order to experimentally test the multi-objective Bayesian optimization method, a novel accelerator diagnostic is being designed to measure multiple beam quality metrics of an electron beam at the Argonne Wakefield Accelerator Facility. Here, we present a design consisting in a pepper-pot mask, a dipole magnet and a scintillation screen, which allows a simultaneous measurement of the electron beam energy spread and vertical emittance. Additionally, a surrogate model for the vertical emittance was constructed with only 60 observations and without prior knowledge of the objective function nor diagnostics constraints.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB304
About •	paper received ※ 18 May 2021 paper accepted ※ 08 June 2021 issue date ※ 26 August 2021
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MOPAB310	Vertical Phase Space Measurement Progress at Canadian Light Source	electron, lattice, synchrotron, experiment	963
	Y. Yousefi Sigari, D. Bertwistle, M.J. Boland CLS, Saskatoon, Saskatchewan, Canada M.J. Boland University of Saskatchewan, Saskatoon, Canada
	A key feature of third-generation light sources is their small vertical opening angle, which is difficult to measure experimentally. To reconstruct the vertical phase space, one can scan the beam’s position using X-ray synchrotron radiation (XSR) and a pinhole camera. The XSR diagnostic beamline, operational in the wavelength region of 0.05 - 0.15 nm, in Canadian Light Source (CLS) is qualified to measure the beam position with X-ray radiation. Using the corrector magnets in CLS lattice made of 12 identical double-bend achromats (DBA) cells, vertical iterations can be executed parallel to the beam’s original orbit. The outcomes of this experiment are: 1) the vertical beam positions that are monitored by BPMs, and 2) the X-ray image of the beam that is projected through the pinhole. The bumps were simulated using Matlab Middle Layer (MML) for Accelerator control systems to get an insight of the source point’s position in the XSR’s bending magnet. The simulation shows the position of the source point depends on which corrector sets are chosen.
	Poster MOPAB310 [0.328 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB310
About •	paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 13 August 2021
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MOPAB318	Beam Characterization of Five Electrode ECR Ion Source	ECR, ECRIS, plasma, experiment	980
	H.M. Kewlani, S. Gharat, S. Krishnagopal, J.V. Mathew, S.V.L.S. Rao BARC, Mumbai, India B. Dikshit, H.M. Kewlani, S. Krishnagopal Homi Bhbha National Institute (HBNI), DAE, Mumbai, India
	A five electrode ECR Ion Source (ECRIS) was developed for the Low Energy High-Intensity Proton Accelerator (LEHIPA) at BARC. The ECRIS is operated at the energy of 50 keV with a beam current of 20 mA. The ECRIS characterization is done for the beam current, beam emittance, and proton fraction in continuous and pulse beam operation. The pulsed beam operation of the ion source starting from 500 µs to 200 ms of pulse on time with a repetition rate of 1 to 10 Hz. The transverse beam emittance measurement is done by using an Allison scanner. The beam emittance characterization experiments are conducted by varying applied microwave power to the plasma, operating gas pressure of plasma and puller voltage. The measured beam emittance is in the range of 0.3 pi.mm. mrad to 0.4 pi.mm. mrad for 50 keV beam. In this paper beam emittance experiment setup and results are discussed.
	Poster MOPAB318 [2.496 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB318
About •	paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 16 August 2021
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MOPAB325	Development of Bunch Width Monitor with High Time Resolution for Low Emittance Muon Beam in the J-PARC Muon g-2 / EDM Experiment	experiment, acceleration, linac, laser	1004
	M. Yotsuzuka, T. Iijima, K. Inami, Y. Sue, K. Sumi Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan T. Iijima KMI, Nagoya, AIchi Prefecture, Japan Y. Kondo JAEA, Ibaraki-ken, Japan T. Mibe KEK, Tsukuba, Japan Y. Nakazawa Ibaraki University, Ibaraki, Japan M. Otani, N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Takeuchi Kyushu University, Fukuoka, Japan H.Y. Yasuda University of Tokyo, Tokyo, Japan
	The J-PARC muon g-2/EDM experiment plans to measure the muon anomalous magnetic moment and electric dipole moment sensitive to new physics with high precision. This experiment uses a novel method using the low-emittance muon beam achieved by cooling and re-acceleration. In the muon linac consisting of four different accelerating cavities, the main cause of the emittance growth is the beam mismatch between the different cavities. Especially for the cavity in the low-beta section (ß=0.08-0.27), the longitudinal acceptance is narrow and beam mismatch has a significant impact. In order to perform beam matching in the low-beta cavity, a new beam monitor that can measure the low-emittance muon beam with high time resolution is required. Therefore, we developed a bunch width monitor (BWM) using a microchannel plate. The time resolution of the BWM was measured to be 40 picoseconds on the test bench using a picosecond pulse laser. It means that the BWM is possible to perform diagnosis with a phase accuracy of 1% for the acceleration phase of 324 MHz. We also evaluated factors that limit the current time resolution. In this presentation, the results of an evaluation of the BWM are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB325
About •	paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 10 August 2021
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MOPAB326	Maximum Entropy Reconstruction of 4D Transverse Phase Space from 2D Projections: with Application to Laser Wire Measurements in the SNS HEBT	laser, neutron, coupling, linac	1008
	C.Y. Wong, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	We employ the principle of maximum entropy (MENT) to reconstruct 4D transverse phase space from its 2D projections. Emittance devices commonly measure two specific 2D projections, i.e. the horizontal and vertical phase space distributions. We show that: 1) given only these two 2D projections, their product is the analytic MENT solution to the 4D distribution; and 2) additional 2D projections provide information on inter-plane coupling in the MENT reconstruction of the 4D phase space which can be solved numerically. At the Spallation Neutron Source (SNS), laser wires in the high energy beam transport (HEBT) enable non-invasive two-slit type transverse phase space measurements. Laser wires play the role of the first slit whereas physical wires downstream of a drift act as the second slit. We reconstruct the 4D phase space in the HEBT using all four horizontal/vertical permutations of the two slits where: 1) the two configurations with parallel slits constitute ordinary 2D phase space measurements in either plane; and 2) the two configurations with perpendicular slits carry coupling information.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB326
About •	paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 17 August 2021
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MOPAB404	A Low Emittance Compact Proton Injector for a Proton Therapy Facility	proton, ion-source, LEBT, rfq	1218
	S.X. Peng, J.E. Chen, B.J. Cui, Z.Y. Guo, Y.X. Jiang, K. Li, T.H. Ma, J. Sun, W.B. Wu, A.L. Zhang, J.F. Zhang PKU, Beijing, People’s Republic of China Y.H. Pu Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China
	To meet the requirements of a Proton Therapy Facility funded by the National Key Research and Development Program of China, a new compact ion source-LEBT integrated proton injector was developed at Peking University (PKU). It consists of a typical PKU permanent magnet compact 2.45 GHz ECR ion source (PMECRIS) and an electrostatic LEBT with an electrostatic lens, a beam chopper, a set of beam steers, an ACCT, a bellow, an e-trap, and a valve. A 1000 L/s molecular pump is adopted to maintain the vacuum for this integrated injector. The length from RF matching plane to RFQ front flange is about 450 mm. Chopper is used to shorten the pulse length from ms to µs with sharp edges. Test results of this PMECR source prove that it has the ability to deliver a proton beam with a current from 10 mA to 90 mA with a duty factor of 3%(100Hz/0.3ms) and its RMS emittance less than 0.1 mm·mrad at 30 keV. The acceptance tests of this integrated injector have been performed with a 30 keV hydrogen beam. A required proton current of 18 mA with ripple wave less than 0.1 mA successfully passed through a 20 mm aperture diaphragm at RFQ entrance flange. Its rms emittance is about 0.06 mm·mrad.
	Poster MOPAB404 [1.946 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB404
About •	paper received ※ 19 May 2021 paper accepted ※ 17 August 2021 issue date ※ 18 August 2021
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TUXA01	Advances in Understanding of Ion Effects in Electron Storage Rings	simulation, ion-effects, storage-ring, injection	1267
	J.R. Calvey, M. Borland, T.K. Clute, J.C. Dooling, L. Emery, J. Gagliano, J.E. Hoyt, P.S. Kallakuri ANL, Lemont, Illinois, USA
	Ion instability, in which beam motion couples with trapped ions in an accelerator, is a serious concern for high-brightness electron storage rings. For the APS-Upgrade, we plan to mitigate coherent ion instability using a compensated gap scheme. To study incoherent effects (such as emittance growth), an IONEFFECTS element has been incorporated into the particle tracking code ELEGANT. The simulations include multiple ionization, transverse impedance, and charge variation between bunches. Once these effects are included, the simulations show good agreement with measurements at the present APS. We have also installed a gas injection system, which creates a controlled pressure bump of Nitrogen gas in a short section of the APS ring. The resulting ion instability was studied under a wide variety of beam conditions. For cases with no or insufficient train gaps, large emittance growth was observed. IONEFFECTS simulations of the gas injection experiment and APS-U storage ring show the possibility of runaway emittance blowup, where the blown-up beam traps more ions, driving further instability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXA01
About •	paper received ※ 24 June 2021 paper accepted ※ 27 July 2021 issue date ※ 10 August 2021
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Paper

Title

Other Keywords

Page

MOXA02

Status of the APS-U Project

lattice, injection, storage-ring, photon

7

R.O. Hettel
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Sci- ence, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357.
The Advanced Photon Source Upgrade (APS-U) project at the Argonne National Laboratory will re-place the existing 7-GeV, 1.1-km circumference dou-ble bend storage ring lattice with a new 6-GeV hybrid 7BA lattice that will reduce horizontal electron emit-tance from 3 nm-rad to 42 pm-rad, including IBS ef-fects for 200-mA operation. With new optimized per-manent magnet and superconducting undulators, an increase in spectral brightness of two to three orders of magnitude in the 10-100 keV X-ray energy range will be realized. The project includes nine new high performance beamlines and fifteen enhanced beam-lines that will exploit the high brightness and coher-ence of the new facility. The project is in full swing, more than 50% complete by cost, and is on schedule for first beam sometime in mid-2024, a slip of 10 months from the original schedule due to the impact of COVID-19. Project status, challenges and outstanding issues will be discussed in this article.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXA02

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paper received ※ 21 May 2021 paper accepted ※ 09 June 2021 issue date ※ 11 August 2021

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MOPAB004

JSPEC - A Simulation Program for IBS and Electron Cooling

electron, simulation, experiment, scattering

49

H. Zhang, S.V. Benson, M.W. Bruker, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Intrabeam scattering is an important collective effect that can deteriorate the properties of a high-intensity beam, and electron cooling is a method to mitigate the IBS effect. JSPEC (JLab Simulation Package for Electron Cooling) is an open-source program developed at Jefferson Lab, which simulates the evolution of the ion beam under the IBS and/or the electron cooling effect. JSPEC has been benchmarked with BETACOOL and experimental data. In this report, we will introduce the features of JSPEC, including the friction force calculation, the IBS expansion rate and electron cooling rate calculation, and the beam-dynamic simulations for the electron cooling process; explain how to set up the simulations in JSPEC; and demonstrate the benchmarking results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB004

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paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 27 August 2021

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MOPAB010

RHIC Beam Energy Scan Operation with Electron Cooling in 2020

operation, luminosity, electron, experiment

72

C. Liu, P. Adams, E.N. Beebe, S. Binello, I. Blackler, M. Blaskiewicz, K.A. Brown, D. Bruno, B.D. Coe, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, C.E. Giorgio, X. Gu, T. Hayes, K. Hock, H. Huang, R.L. Hulsart, T. Kanesue, D. Kayran, N.A. Kling, B. Lepore, Y. Luo, D. Maffei, G.J. Marr, A. Marusic, K. Mernick, R.J. Michnoff, M.G. Minty, J. Morris, C. Naylor, S. Nemesure, M. Okamura, I. Pinayev, S. Polizzo, D. Raparia, G. Robert-Demolaize, T. Roser, J. Sandberg, V. Schoefer, S. Seletskiy, F. Severino, T.C. Shrey, P. Thieberger, M. Valette, A. Zaltsman, I. Zane, K. Zeno, W. Zhang
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.
RHIC provided Au-Au collisions at beam energies of 5.75 and 4.59 GeV/nucleon for the physics program in 2020 as a part of the Beam Energy Scan II experiment. The operational experience at these energies will be reported with emphasis on their unique features. These unique features include the addition of a third harmonic RF system to enable a large longitudinal acceptance at 5.75 GeV/nucleon, the application of additional lower frequency cavities for alleviating space charge effects, and the world-first operation of cooling with an RF-accelerated bunched electron beam.

Poster MOPAB010 [3.523 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB010

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paper received ※ 17 May 2021 paper accepted ※ 29 July 2021 issue date ※ 10 August 2021

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MOPAB016

Small Longitudinal Emittance Setup in Injectors with Gold Beam for Beam Energy Scan in RHIC

operation, luminosity, extraction, cavity

90

H. Huang, C.J. Gardner, C. Liu, V. Schoefer, K. Zeno
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In recent years, RHIC physics program calls for gold beam collisions with energies at and lower than the nominal RHIC injection energy. To get shorter bunches at the three higher energies (9.8GeV/c, 7.3GeV/c and 4.75GeV/c), RHIC 28MHz cavities were used. The longitudinal emittance out of injectors needs to fit in the 28MHz cavities in RHIC. At two lower energies (4.6 and 3.85 GeV/c), the 9MHz RF cavities were used, which set different requirements from injectors. Extensive beam studies were carried out to establish needed beam parameters, such as bunch intensities and longitudinal emittances. In general, enough intensity can be provided for all energies within the longitudinal emittance constraint. This paper summarizes the recent injector operation experiences for various energies.

Poster MOPAB016 [2.641 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB016

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paper received ※ 16 May 2021 paper accepted ※ 17 August 2021 issue date ※ 01 September 2021

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MOPAB019

Possible Application of Round-to-Flat Hadron Beam Creation Using 3rd Order Coupling Resonances for the Electron-Ion Collider

resonance, sextupole, coupling, electron

99

J. Kallestrup
PSI, Villigen PSI, Switzerland
X. Gu
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.
An Electron-Ion Collider (EIC) is planned to be built in Brookhaven National Laboratory with the contribution from Jefferson National Laboratory. To have a high luminosity, both the EIC ion bunch and the EIC electron bunch are designed to be flat during their collision. The existing injector source provides a round beam of width 2.5 um rad transverse emittances. In this paper we investigate the option of dynamically crossing the 2Qx-Qy coupling resonance in order to create a flat-beam with emittance ratio Ex/Ey of up to 4. Furthermore, we explore the possibility of using a pulsed- or AC skew sextupole magnets to achieve a similar effect. Using one of these methods for flat beam creation will help lower the ion beam cooling time.

Poster MOPAB019 [0.323 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB019

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021

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MOPAB020

Improvements to the SLS Booster Synchrotron Performance Towards SLS 2.0

booster, sextupole, coupling, injection

103

J. Kallestrup, M. Aiba
PSI, Villigen PSI, Switzerland

The Swiss Light Source (SLS) storage ring will undergo a major upgrade to a multi-bend achromat lattice. The existing injector complex will be reused with few modifications. However, the SLS booster synchrotron has not been studied since the initial commissioning in years 2000-2001. We plan to apply an emittance exchange in the booster to lower the horizontal emittance, which is a critial parameter for the injection. Here, we present improvements to the SLS booster as a preparation for SLS 2.0 upgrade project. The vertical beam size is decreased by 50\% by the use of vertical orbit correctors without beam position monitors, leading also to suppression of vertical dispersion and a factor 10 reduction of the transverse coupling coefficient. The emittance exchange reflected these improvements in the horizontal emittance, achieving a factor of 9-10 reduction. Lastly, a fast head-tail instability limiting the injection rate into the storage ring is discovered and subsequently suppressed by correcting the chromaticities.

Poster MOPAB020 [0.380 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB020

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paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 30 August 2021

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MOPAB021

A Dispersive Quadrupole Scan Technique for Transverse Beam Characterization

quadrupole, SRF, optics, booster

107

J. Kallestrup, M. Aiba
PSI, Villigen PSI, Switzerland
N. Carmignani, T.P. Perron
ESRF, Grenoble, France

Quadrupole scans are one of the standard techniques to characterize the transverse beam properties in transfer lines or linacs. However, in the presence of dispersion the usage of regular quadrupole scans will lead to erroneous estimates of the beam parameters. The standard solution to this problem is to measure the dispersion and then subtract it in the post-analysis of the quadrupole scan measurements assuming the design energy spread. Here we show that the dispersive contribution to the beam size can be included in the quadrupole scan procedure, forming a linear system of equations that can be solved to obtain both the betatronic and dispersive beam parameters. The method is tested at both the SLS and ESRF booster-to-ring transfer lines leading to reasonable estimates of the beam parameters.

Poster MOPAB021 [0.447 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB021

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 19 August 2021

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MOPAB023

Experimental Test of a New Method to Verify Retraction Margins Between Dump Absorbers and Tertiary Collimators at the LHC

experiment, alignment, beam-losses, operation

115

C. Wiesner, W. Bartmann, C. Bracco, R. Bruce, J. Molson, M. Schaumann, C. Staufenbiel, J.A. Uythoven, M. Valette, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Meyrin, Switzerland

The protection of the tertiary collimators (TCTs) and the LHC triplet aperture in case of a so-called asynchronous beam dump relies on the correct retraction between the TCTs and the dump region absorbers. A new method to validate this retraction has been proposed, and a proof-of-principle experiment was performed at the LHC. The method uses a long orbit bump to mimic the change of the beam trajectory caused by an asynchronous firing of the extraction kickers. It can, thus, be performed with circulating beam. This paper reports on the performed beam measurements, compares them with expectations and discusses the potential benefits of the new method for machine protection.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB023

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paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 24 August 2021

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MOPAB029

Burn-Off with Asymmetric Interaction Points

luminosity, experiment, simulation, controls

138

R. Tomás García, I. Efthymiopoulos, G. Iadarola
CERN, Geneva, Switzerland

LHC can host above 2700 proton bunches per ring providing collisions in the ATLAS, CMS, LHCb and ALICE interaction points. ATLAS and CMS are placed symmetrically so that they feature the same colliding bunch pairs. However this is not the case for LHCb, hence introducing unwanted bunch-by-bunch variations of the bunch intensity as the physics fill evolves. We present first analytical derivations, numerical simulations and experimental data in different bunch train collision configurations.

Poster MOPAB029 [1.502 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB029

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paper received ※ 13 May 2021 paper accepted ※ 25 May 2021 issue date ※ 27 August 2021

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MOPAB032

Estimates of Collective Effects for the FCC-e⁺e⁻ Pre-Booster Ring

impedance, electron, injection, collective-effects

148

O. Etisken, F. Antoniou, K. Oide, Y. Papaphilippou, F. Zimmermann
CERN, Geneva, Switzerland
A.K. Çiftçi
Izmir University of Economics, Balçova/Izmir, Turkey

The FCC-e⁺e⁻ injector complex needs to produce and to transport high-intensity e⁺ and e^- beams at a fast repetition rate for topping up the collider at its collision energy. Two different options are under consideration as pre-accelerator before the bunches are transferred to the high-energy booster: either using the existing SPS machine or designing a completely new ring. The purpose of this paper is to present the studies of collective effects with analytical estimates for both the pre-booster ring design options including space charge (SC), longitudinal micro-wave instability (LMI), transverse mode coupling instability (TMCI), ion effects, electron cloud (e-cloud), coherent synchrotron radiation (CSR), and intra-beam scattering (IBS).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB032

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paper received ※ 17 May 2021 paper accepted ※ 27 May 2021 issue date ※ 15 August 2021

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MOPAB033

Monochromatization of e⁺e⁻ Colliders with a Large Crossing Angle

resonance, collider, luminosity, radiation

152

V.I. Telnov
BINP SB RAS, Novosibirsk, Russia

The relative center-of-mass energy spread at e⁺e⁻ colliders is much larger than the widths of narrow resonances, which greatly lowers the resonance production rates of J/Psi, Psi-prime, Upsililon(nS), n=1-3. Thus, a significant reduction of the center-of-mass energy spread would open up great opportunities in the search for new physics in rare decays of narrow resonances, the search for new narrow states with small partial e⁺e⁻ width. The existing monochromatization scheme is only suitable for head-on collisions, while e⁺e⁻ colliders with crossing angles (the so-called Crab Waist collision scheme) can provide much higher luminosity. In this report, a new monochromatization method for colliders with a large crossing angle is discussed*. The contribution of the beam energy spread to the spread of the center-of-mass energy is canceled by introducing an appropriate energy-angle correlation at the interaction point; the relative RMS mass spread of about (3-5)10^-6 seems possible. Limitations of the proposed method are also considered. This monochromatization scheme is very attractive for the Upsilon-meson region and below.
* V.I.Telnov, Monochromatization of e⁺e⁻ colliders with a large crossing angle, arXiv:2008.13668

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB033

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paper received ※ 22 May 2021 paper accepted ※ 26 May 2021 issue date ※ 31 August 2021

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MOPAB046

Plan for Operating the APS-Upgrade Booster with a Frequency Sweep

injection, booster, extraction, cavity

201

J.R. Calvey, T.G. Berenc, A.R. Brill, L. Emery, T. Fors, K.C. Harkay, T.J. Madden, N. Sereno, U. Wienands
ANL, Lemont, Illinois, USA
A. Gu
UCB, Berkeley, California, USA

The APS-Upgrade presents several challenging demands to the booster synchrotron. Swap-out injection requires the booster to capture a high charge bunch (up to 17 nC), accelerate it to 6 GeV, and maintain a low emittance at extraction for injection into the storage ring. To accommodate these conflicting demands, the RF frequency will be ramped between injection and extraction. However, the RF cavity tuners will remain static, which means the couplers will need to withstand a high reflected power at extraction. This paper presents a plan for a system that will meet the requirements for injection efficiency, extracted emittance, and equivalent power at the coupler. Results from tracking simulations and beam studies with a frequency ramp will also be shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB046

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paper received ※ 28 May 2021 paper accepted ※ 02 June 2021 issue date ※ 26 August 2021

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MOPAB051

Operation of the ESRF Booster with the New EBS Storage Ring

booster, SRF, injection, operation

221

N. Carmignani, L.R. Carver, S.M. Liuzzo, T.P. Perron, S.M. White
ESRF, Grenoble, France

The Extremely Brilliant Source (EBS) has replaced the old ESRF Storage Ring (SR) during the 2019 one-year shutdown. The injector chain, composed of a Linac, a booster synchrotron, and two transfer lines, was not replaced. Nevertheless, some major hardware upgrades were anticipated prior to the long shutdown to ensure its long-term reliability. The shutdown interventions focused on reducing the machine circumference to cope with the new RF frequency of the SR. The status of the upgraded booster will be presented with a focus on the strategy used to lower horizontal emittance especially via emittance exchange.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB051

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paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 25 August 2021

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MOPAB055

Generation of Coherent Attosecond X-ray Pulses in the Southern Advanced Photon Source

laser, electron, storage-ring, photon

237

W. Liu, Y. Zhao
IHEP CSNS, Guangdong Province, People’s Republic of China
Y. Jiao, S. Wang
IHEP, Beijing, People’s Republic of China

Southern Advanced Photon Source (SAPS) is a fourth-generation storage ring light source that has been considered for construction in Guangdong province of China, adjacent to the China Spallation Neutron Source. As a low-emittance storage ring, the natural emittance of SAPS is below 100 pm. One of the benefits is that the brightness is about 2 orders high than 3rd generation light sources. However, like many other storage ring-based light sources, the time resolution is limited by the electron bunch length in the range of picoseconds. In this work, we propose a new scheme for the generation of coherent attoseconds X-ray pulses with a high repetition rate in SAPS. A numerical demonstration of the scheme is presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB055

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paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021

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MOPAB056

Optimization of a TBA with Stable Optics and Minimal Longitudinal Dispersion and CSR-Induced Emittance Growth

bunching, synchrotron, quadrupole, FEL

241

C. Zhang, Y. Jiao
IHEP, Beijing, People’s Republic of China
C.-Y. Tsai
HUST, Wuhan, People’s Republic of China

Funding: National Natural Science Foundation of China (No. 11922512), Youth Innovation Promotion Association of Chinese Academy of Sciences (No. Y201904), National Key R&D Program of China (No. 2016YFA0401900)
In the beam transfer line which often consists of dipoles to deflect the beam trajectory, longitudinal dispersion effect and emission of coherent synchrotron radiation (CSR) will lead to beam phase space distortion, thus degrading the machine performance. In this study, optimizations of a triple-bend achromat (TBA) cell are conducted using the multi-objective particle swarm optimization (MOPSO) method to suppress the CSR-induced emittance growth and minimize the longitudinal dispersion functions up to high orders, simultaneously. For the longitudinal dispersion function, results of three optimization settings are reported, which makes the TBA design first-order, second-order, and higher-order isochronous. Furthermore, we study the shortest possible beamline length of the higher-order isochronous TBA design, which may pave the way to designing a more compact beam transfer line.

Poster MOPAB056 [0.366 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB056

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paper received ※ 12 May 2021 paper accepted ※ 28 May 2021 issue date ※ 15 August 2021

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MOPAB057

Evaluation of Pulsed Septum Leakage Fields and Compensation for the Advanced Photon Source Upgrade

septum, simulation, power-supply, injection

245

M. Borland, M.S. Jaski, J. Wang
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source upgrade is considering two options for injection: vertical-plane injection with a DC Lambertson septum and horizontal-plane injection with a pulsed septum. In the latter case, pulsed leakage fields are a concern as they will cause transient beam motion and emittance dilution. In this paper, we describe results of modeling the effect of such leakage fields on the beam. We also evaluate methods of compensating for the leakage fields, including the limited time response of correction elements. Several septum drive-pulse shapes are considered and compared.

Poster MOPAB057 [2.066 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB057

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paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 02 September 2021

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MOPAB062

A Single Dipole Source for Broad-Band Soft Photon Beamlines in Diamond-II

lattice, dipole, dynamic-aperture, linear-dynamics

261

M. Apollonio, G. Cinque, H. Ghasem, A.N. Jury, I.P.S. Martin, R. Rambo
DLS, Oxfordshire, United Kingdom

Diamond-II is a project based at Diamond Light Source for an upgrade towards a Storage Ring characterized by a reduction of a factor 20 in its natural emittance and a doubling of the number of straight sections. At Diamond-II the majority of existing beamline capacity should be maintained, while enhancing their performance thanks to the increase in brightness at the source points. The substantial modification of the lattice imposes a likewise re-design of the broad-band sources, presently based on standard dipoles. In this paper we discuss a possible solution for the IR/THz beamline B22 operating within a photon energy range between 1meV and 1eV. This proposal, ideal for low critical energy and single source point sources, entails the insertion of a dipole in one of the newly created mid-cell straights of the machine, while reducing the bending power of the nearby gradient dipoles. After performing the linear matching of the lattice, reproducing a comparable phase advance in the modified cell, we studied the non-linear dynamics of the system. Comparison of the main observables (Dynamic Aperture, Injection Efficiency and Lifetime) with the baseline case is discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB062

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paper received ※ 18 May 2021 paper accepted ※ 28 May 2021 issue date ※ 12 August 2021

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MOPAB065

Optimization of the Lattice Replacement Options for the Next Generation Australian Synchrotron

lattice, synchrotron, storage-ring, sextupole

269

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

The design of a next generation Australian Synchrotron replacement lattice is a multi-objective and multi-constrained problem. Our group was tasked to produce a low emittance design while re-using the existing tunnel infrastructure and injector system. Our objectives coupled with the set infrastructure constraints are not straightforward to achieve with manual design. Several variables act at cross-purposes to one-another, leading to a conflicting trade-off between objectives. Recently we have investigated replacement options for the Australian Synchrotron containing longitudinal gradient and reverse bends in the form of a 4BA (4-bend achromat) lattice. In this work, optimise the lattice design for a potential fourth generation Australian Synchrotron facility. We outline the baseline 4BA solution to the lowest emittance lattice that can reuse the existing tunnels and injector system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB065

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paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 19 August 2021

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MOPAB066

Dual Octupole Emittance Growth Correction of the CompactLight XFEL Bunch Compressors

octupole, FEL, lattice, linac

272

R. Auchettl, R.T. Dowd
AS - ANSTO, Clayton, Australia

An optimized CompactLight X-Ray Free Electron Laser (FEL) bunch compressor design is presented. In this work, we insert an octupole into the center of the two sequential bunch compressors. We show how this scheme can adjust the compression, while correcting the undesirable peak current profile and emittance growth.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB066

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paper received ※ 24 May 2021 paper accepted ※ 28 May 2021 issue date ※ 24 August 2021

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MOPAB071

Progress with the Booster Design for the Diamond-II Upgrade

booster, injection, storage-ring, extraction

286

I.P.S. Martin, C. Christou, M.P. Cox, R.T. Fielder, J. Kallestrup, A. Shahveh, W. Tizzano
DLS, Oxfordshire, United Kingdom
A.D. Brynes, J.K. Jones, B.D. Muratori, H.L. Owen
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Efficient injection into the Diamond-II storage ring [*, **] will require an emittance and bunch length substantially below the values produced from the existing booster. Whilst an earlier design for a replacement based on TME cells was able to meet the target values of <30 nm.rad and <40 ps respectively [***, ****], several technical constraints have led to a rethink of this solution. The revised booster lattice utilises a larger number of cells based on combined-function magnets with lower peak fields that still meets the emittance and bunch length goals. In addition, the new ring has been designed to have low impedance to maximise the extracted charge per shot. In this paper we describe the main features of the lattice, present the status of the engineering design and quantify the expected performance.
*Diamond-II Conceptual Design Report, Diamond Light Source
**H. Ghasem et al, these proceedings
***I. Martin, R. Bartolini, J.Phys.:Conf. Ser., 1067, 032005
****I. Martin et al, IPAC 2019, WEPMP042

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB071

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paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 02 September 2021

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MOPAB074

Preliminary Study of Design Method for Hybrid MBA Lattice

lattice, resonance, linear-dynamics, sextupole

297

J.J. Tan, Z.H. Bai, Z.L. Ren, J.H. Xu
USTC/NSRL, Hefei, Anhui, People’s Republic of China
Q. Zhang
INEST, Hefei, People’s Republic of China

Nonlinear optimization of hybrid multi-bend-achromat (HMBA) lattice is a difficult task due to its quite limited variables of multipole magnets. As a result, it is necessary to consider nonlinear potential of the lattice in its linear design. Nonlinear dynamics can be estimated by nonlinear driving terms and detuning terms. In this paper, we propose a design method for HMBA lattice. In this method, objective functions include emittance and two indicators of nonlinear dynamics, which consist of nonlinear driving terms and detuning terms. As an example, an HMBA lattice for a 2.2 GeV storage ring with circumference of 460.8 m was designed to demonstrate the method.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB074

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paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 21 August 2021

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MOPAB075

Proposal of the Southern Advanced Photon Source and Current Physics Design Study

photon, linac, storage-ring, lattice

300

S. Wang, J. Chen, L. Huang, Y. Jiao, B. Li, Z.P. Li, W. Liu, S.Y. Xu
IHEP, Beijing, People’s Republic of China
Y. Han, X.H. Lu, Y. Zhao
IHEP CSNS, Guangdong Province, People’s Republic of China
X. Liu
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan

It has been considered to build a mid-energy fourth-generation storage ring light source neighbouring the China Spallation Neutron Source, in Guangdong Province, the south of China. The light source is named the Southern Advanced Photon Source (SAPS). Preliminary physics design studies on the SAPS have been implemented for a few years. In this paper, we will describe considerations of technical roadmap and key parameter choice for this light source, and introduce the up-to-date lattice designs and related physics studies on the SAPS.

Poster MOPAB075 [1.689 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB075

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paper received ※ 12 May 2021 paper accepted ※ 20 May 2021 issue date ※ 21 August 2021

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MOPAB089

Effect of Different Models of Combined-function Dipoles on the HEPS Parameters

dipole, lattice, storage-ring, quadrupole

335

Y.Y. Guo, Y. Jiao, N. Li
IHEP, Beijing, People’s Republic of China

The high energy photon source (HEPS) is a 6 GeV, kilometer-scale storage ring light source being built in Beijing, China. In the current ring lattice, the combined-function dipoles are used and assumed to have constant dipole field. However, in the actual magnet design, an eccentrically placed quadrupole is adopted, in which the bending field along the trajectory is not constant. In this paper, we will present the effect of the two models of combined-function dipoles on the parameters of the storage ring.

Poster MOPAB089 [0.590 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB089

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paper received ※ 13 May 2021 paper accepted ※ 25 May 2021 issue date ※ 27 August 2021

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MOPAB095

Concept Design for the CLS2 Accelerator Complex

electron, storage-ring, synchrotron, lattice

354

M.J. Boland, P.J. Hunchak
University of Saskatchewan, Saskatoon, Canada
C.K. Baribeau, D. Bertwistle, J.M. Patel, H. Shaker, X. Shen, M.J. Sigrist
CLS, Saskatoon, Saskatchewan, Canada
F. Le Pimpec
EuXFEL, Schenefeld, Germany
E.J. Wallén
LBNL, Berkeley, California, USA

The Canadian Light Source has been in operation since 2005 and is now looking at a design concept to upgrade to a fourth generation storage ring. A brief overview is given of a possible accelerator complex layout, including some details on the lattice design and injection system. A full energy linac is being explored as an option for top-up injection and to future proof the facility for a potential FEL upgrade in the future.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB095

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paper received ※ 23 May 2021 paper accepted ※ 28 July 2021 issue date ※ 13 August 2021

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MOPAB101

Hollow and Flat Electron Beam Generation at FACET-II

electron, wakefield, quadrupole, experiment

376

A. Halavanau, S.J. Gessner, C.E. Mayes
SLAC, Menlo Park, California, USA
J.B. Rosenzweig
UCLA, Los Angeles, California, USA

In this proceeding, we investigate hollow and flat electron beam generation at FACET-II facility. We focus on the case of a circular beamlet arrangement, also known as ’necklace’ beams. We study, via numerical simulations, the resulting e-beam dynamics in the FACET-II photoinjector, beam propagation through the high energy section, as well as possible experimental applications of the ’necklace’ beams. Finally, we evaluate the feasibility of high charge flat beam generation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB101

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paper received ※ 23 May 2021 paper accepted ※ 27 July 2021 issue date ※ 23 August 2021

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MOPAB103

Study of Transverse Oscillation Coupling and Possibility of Its Minimization in SKIF (Novosibirsk)

coupling, quadrupole, sextupole, storage-ring

383

D. Leshenok
BINP, Novosibirsk, Russia
G.N. Baranov, E.B. Levichev, S.A. Nikitin
BINP SB RAS, Novosibirsk, Russia

The vertical emittance and, in general, the vertical beam size and angular divergence are of paramount importance in the SKIF (Russian acronym for Siberian Circular Photon Source) project developed in Novosibirsk. Therefore, a detailed simulation of the corresponding influence of possible errors in the storage ring was carried out with cross-validation by different methods. Variants of cross-coupling correction are proposed and modeled to obtain a vertical emittance of the order of one picometer simultaneously with minimizing vertical dispersion.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB103

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paper received ※ 18 May 2021 paper accepted ※ 17 August 2021 issue date ※ 19 August 2021

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MOPAB106

Enhancing the MOGA Optimization Process at ALS-U with Machine Learning

lattice, dynamic-aperture, sextupole, storage-ring

387

Y. Lu, M.P. Ehrlichman, T. Hellert, S.C. Leemann, H. Nishimura, C. Sun, M. Venturini
LBNL, Berkeley, California, USA

Funding: This research is funded by the US Department of Energy(BES & ASCR Programs), and supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231.
The bare lattice optimization for the linear and nonlinear ALS-U storage ring lattice, even without reverse bending, comprises 11 degrees of freedom (DoF) and is therefore a very complex and highly time-consuming process. This design process relies heavily on multi-objective genetic algorithms (MOGA), usually requiring many months of experienced scientists’ time. The main problem lies in having to evaluate numbers of candidate lattices due to the stochastic process of MOGA. Although almost all of these candidates are eventually rejected, they nevertheless require extensive particle tracking to arrive at a Pareto front. We therefore propose a novel Machine Learning (ML) pipeline that nonlinear tracking is replaced by two well-trained neural networks (NNs) to predict dynamic aperture (DA) and momentum aperture (MA) for any lattice candidate. Initial training of these models takes only several minutes on conventional CPUs while predictions are then rendered near instantaneously. We present this novel method and demonstrate the resulting orders of magnitude speedup of the ML-enhanced MOGA process on a 2-DoF problem as well as first results on a more complex 11-DoF problem.

Poster MOPAB106 [0.918 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB106

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paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 18 August 2021

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MOPAB109

A Lattice for PETRA IV Based on the Combination of Different Arc Cell Designs

lattice, undulator, sextupole, resonance

399

J. Keil, I.V. Agapov, R. Brinkmann
DESY, Hamburg, Germany

The 6 GeV synchrotron light source PETRA III at DESY is in user operation since 2009. In 2016 investigations of upgrading PETRA III into a diffraction limited storage ring at 10 keV have been started. The ambitious goal is to achieve an emittance in the range of 10-30 pm*rad. For the conceptual design report (CDR) of PETRA IV a lattice based on hybrid multi-bend achromats (HMBA) has been chosen. It consists of eight arcs connected by eight long straight sections whereas each arc consists of eight HMBA cells. While this lattice variant has an advantage in terms of simplicity of magnet and girder design it is challenging in regards of multipole strengths and beam dynamic properties. However, only a part of all eight arcs will be used for undulator beamlines. This offers the possibility to choose a more relaxed optics design in the arcs without undulators while preserving the ultra-low emittance. In addition, the use of reverse bends in the undulator cells allows smaller beta functions at the undulators for an increased brilliance. The design and the beam dynamic properties of this combi lattice are discussed in this paper and compared to the lattice based on HMBA cells.

Poster MOPAB109 [1.338 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB109

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paper received ※ 18 May 2021 paper accepted ※ 28 May 2021 issue date ※ 30 August 2021

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MOPAB110

An Electron Synchrotron Lattice Based on Theoretic Minimal Emittance Cell

lattice, extraction, sextupole, synchrotron

403

H.C. Chao
DESY, Hamburg, Germany

A design of an electron synchrotron featuring the theoretic minimal emittance (TME) cells is presented. It has 32 superperiods and the circumference is around 300 m. It offers versatile functions with the equilibrium emittance less than 10 nm-rad at 6 GeV. The beam energy can go up to 7 GeV. Locations with proper phase advances are found to form effective vertical orbit bumps, which can be used for the injections and extraction. A tune scan study shows the sweet spot for the working point. Some discussions of other usages and studies of synchro-betatron coupling effects are also included in this article.

Poster MOPAB110 [0.777 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB110

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paper received ※ 11 May 2021 paper accepted ※ 28 May 2021 issue date ※ 30 August 2021

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MOPAB112

A Modified Hybrid 6BA Lattice for the HALF Storage Ring

lattice, damping, storage-ring, SRF

407

Z.H. Bai, G.Y. Feng, T.L. He, W. Li, W.W. Li, G. Liu, Z.L. Ren, L. Wang, P.H. Yang, S.C. Zhang, T. Zhang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

In this paper, we propose a modified hybrid 6BA lattice as the baseline lattice of the Hefei Advanced Light Facility (HALF) storage ring. Similar to the Diamond-II lattice, the proposed lattice cell has one long straight section and one mid-straight section; but the two bend units adjacent to the mid-straight are LGB/RB units (LGB: longitudinal gradient bend, RB: reverse bend), which can give both lower emittance and shorter damping times. The designed HALF storage ring, with an energy of 2.2 GeV and 20 lattice cells, has a natural emittance of about 85 pm·rad.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB112

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paper received ※ 15 May 2021 paper accepted ※ 20 May 2021 issue date ※ 01 September 2021

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MOPAB113

A Low-emittance Booster Lattice Design for the SOLEIL Upgrade

booster, lattice, storage-ring, linear-dynamics

410

M.-A. Tordeux, A. Loulergue, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France
Z.H. Bai, G. Liu, T. Zhang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

The SOLEIL storage ring upgrade will require an injected beam with small transverse and longitudinal sizes. To meet this requirement, the present booster also needs to be upgraded, aiming to reduce the emittance below 10 nm·rad. A multi-bend achromat lattice is designed in this context for the booster upgrade, which consists of two superperiods to respect the present race-track configuration. The lattice is a 16BA HOA (Higher-Order Achromat) type lattice, composed of 14 unit cells, 2 matching cells and a long straight section, and combined-function bending magnets are used in the unit cells to both save space and reduce the emittance. The natural emittance of the designed booster is 5.2 nm·rad at the final energy of 2.75 GeV. This paper presents the general constraints, linear lattice design and nonlinear dynamics optimization for the booster upgrade.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB113

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paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 26 August 2021

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MOPAB119

Comparisons Between AT and Elegant Tracking

lattice, closed-orbit, simulation, dynamic-aperture

432

G. Penn, T. Hellert, M. Venturini
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DEAC02-05CH11231.
The simulation codes Elegant* and Accelerator Toolbox (AT)** are both in common use for the study of particle accelerators and light sources. They use different software platforms and have different capabilities, so there is a strong motivation to be able to switch from one version to another to achieve different goals. In addition, it is useful to directly compare results for benchmarking studies. We discuss differences in tracking methods and results for various elements, and explore the impact on simulations performed with lattices designed for the ALS-U. In addition to single-particle tracking, global properties such as chromaticity, dynamics aperture, momentum aperture and beam lifetime are also investigated. We have also developed scripts to translate AT lattices into elegant lattice files to facilitate comparisons.
* M. Borland, Advanced Photon Source LS-287, September 2000.
** A. Terebilo, Particle Accelerators Conference 2001, p. 3203.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB119

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paper received ※ 20 May 2021 paper accepted ※ 31 May 2021 issue date ※ 30 August 2021

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MOPAB126

BESSY III & MLS II - Status of the Development of the New Photon Science Facility in Berlin

undulator, radiation, lattice, photon

451

P. Goslawski, M. Abo-Bakr, F. Andreas, M. Arlandoo, J. Bengtsson, V. Dürr, K. Holldack, J.-G. Hwang, A. Jankowiak, B.C. Kuske, J. Li, A.N. Matveenko, T. Mertens, A. Meseck, E.C.M. Rial, M. Ries, M.K. Sauerborn, A. Schälicke, M. Scheer, P. Schnizer, L. Shi, J. Viefhaus
HZB, Berlin, Germany
J. Lüning
UPMC, Paris, France

HZB operates and develops two synchrotron radiation sources at Berlin Adlershof. The larger one, BESSY II with an energy of 1.7 GeV and 240 m circumference is optimized for soft-X rays and in operation since 1999. The smaller one is the MLS (Metrology Light Source), owned by the Physikalische Technische Bundesanstalt (PTB) - Germany’s National Metrology Institute. It is designed to fulfill the special metrology needs of the PTB with an energy of 0.6 GeV and 48 m circumference, covering the spectral range from THz and IR to EUV/VUV. In 2020 a discussion process has been started to define the requirements for successors of BESSY II and MLS and to study the possibilities integrate them into a new photon science facility in Berlin Adlershof. Here, we give a status report and present a first envisaged parameter space to both machines (see also MOPAB262, MOPAB220, MOPAB048, MOPAB242).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB126

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paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 18 August 2021

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MOPAB131

Synchrotron SOLEIL Upgrade Project

lattice, photon, vacuum, injection

463

A. Nadji
SOLEIL, Gif-sur-Yvette, France

To remain competitive in the future, SOLEIL is also working on an upgrade project plan based on Multi-Bend Achromat (MBA) lattices. The Technical Design Report of the project is expected to start in early 2021 immediately after the completion of the Conceptual Design Report (CDR) phase. The achieved equilibrium emittance in the CDR reference lattice (80 pm-rad) is about 50 times smaller than that of the existing storage ring (4000 pm-rad). By operating on a linear coupling resonance, round beam sizes in Insertion Devices straight sections of less than 10 microns RMS in both planes can be produced. These performances rely on the use of a 10 mm inner diameter circular copper vacuum chamber with NEG-coating allowing reaching strong quadrupole gradients and very strong sextupole and octupole strengths. As all these technical challenges are pushing the engineering technology to the limits, they are being investigated through an intensive R&D program based on extensive numerical simulations, prototyping, and measurement with the beam. Extensive use of the pure permanent magnet technology beyond what has been done so far in the other similar projects is considered in this project.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB131

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paper received ※ 22 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021

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MOPAB133

Recovering the Positron Beam After Muon Production in the Lemma Muon Source

target, positron, linac, injection

470

I. Drebot
INFN-Milano, Milano, Italy
M.E. Biagini, O.R. Blanco-García, A. Giribono, S. Guiducci, C. Vaccarezza, A. Variola
INFN/LNF, Frascati, Italy
S.M. Liuzzo
ESRF, Grenoble, France

In the LEMMA muon source proposal* a positron beam at 45 GeV is used to produce muons at threshold by interaction with some targets. In order to release the required intensity on the main positron source, orders of magnitude higher than the state of the art, the possibility to recover the primary positron beam after the interaction with the targets was studied. The particles distribution, with a strongly degraded energy spread after the interac- tion, was injected back into a low emittance, large energy acceptance 45 GeV ring. Studies of injection efficiency were performed. The possibility of compressing the beam in a linac before injection was also studied. As a result, even without compression, about 80% of the disrupted e⁺ beam can be injected back into the ring.
* D. Alesini et al, "Positron driven muon source for a muon collider", arXiv:1905.05747v2 [physics.acc-ph], May 2019

Poster MOPAB133 [4.171 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB133

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paper received ※ 17 May 2021 paper accepted ※ 24 May 2021 issue date ※ 20 August 2021

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MOPAB134

Normalized Transverse Emittance Reduction via Ionization Cooling in MICE ’Flip Mode’

simulation, solenoid, experiment, betatron

474

P.B. Jurj
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

Low emittance muon beams are central to the development of a Muon Collider and can significantly enhance the performance of a Neutrino Factory. The international Muon Ionization Cooling Experiment (MICE) has recorded several million individual muon tracks passing through a liquid hydrogen or a lithium hydride absorber and has demonstrated the ionization cooling of muon beams. Previous analysis used a restricted data set, and the beam matching was not perfect. In this analysis, beam sampling routines were employed to account for imperfections in beam matching at the entrance into the cooling channel and enable an improvement of the cooling measurement. A study of the normalized transverse emittance change in the MICE cooling channel set up in a flipped polarity magnetic field configuration is presented. Additionally, the evolution of the canonical angular momentum across the absorber is shown and the characteristics of the cooling effect are discussed.

Poster MOPAB134 [1.821 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB134

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021

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MOPAB149

Ion Motion in Flat Beam Plasma Accelerators

plasma, electron, collider, linear-collider

521

M. Yadav, C.E. Hansel, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
O. Apsimon, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was supported by UCLA and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1. This work is done on SCARF Cluster.
Intense beams, such as those in proposed plasma based linear colliders, can not only blow out electrons to form a bubble but can also attract ions towards the beam. This violates the assumption that the ions are stationary on the timescale of the beam, which is a common assumption for shorter and less intense beams. While some research has been done on understanding the physics of ion motion in blowout Plasma Wakefield Accelerators (PWFAs), this research has almost exclusively focused on cylindrically symmetric beams, rather than flat asymmetric emittance beams which are often used in linear colliders in order to minimize beamstrahlung at the final focus. This contribution investigates both analytically and computationally ion motion of a flat beam scenario in order to understand the basic physics as well as how to mitigate emittance growth, beam hosing and quadrupole.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB149

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paper received ※ 24 May 2021 paper accepted ※ 17 June 2021 issue date ※ 11 August 2021

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MOPAB153

Laser Microfabrication for Accelerator Applications

laser, FEM, simulation, cathode

535

S.P. Antipov, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Laser microfabrication allows high precision ablation of materials at sub-mm scale. When laser pulse length is shorter than about 10 picoseconds the heat affected zone is minimized and ablation occurs without melting. Work-pieces processed in this fashion exhibit less structural damage and are expected to have a higher damage thresholds. In this paper we will review several case studies of laser-microfabricated components for accelerator and x-ray applications. Ablated materials include diamond, quartz, tungsten, copper, YAG:Ce and silicon.

Poster MOPAB153 [2.781 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB153

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paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 29 August 2021

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MOPAB191

Method Development for Cavity Failure Compensation in a Superconducting Linac

cavity, linac, lattice, ECR

647

F. Bouly
LPSC, Grenoble Cedex, France

Reliability is a major challenge within the perspective of improving the performances and sustainability of MegaWatt class accelerators. To optimize the operational costs of such accelerators the availability requirements are becoming more and more challenging. These requirements are even more stringent in the case of Accelerator Driven systems (ADS). As an example, for the MYRRHA (Multipurpose Hybrid Research Reactor for High-tech Applications) ADS demonstrator, the actual availability limit is set to a maximum of 10 beam interruptions (longer than 3 seconds) over a 3-month operating cycle. For this purpose, the accelerator design is based on a redundant and fault-tolerant scheme to enable rapid mitigation of a cavity failure. The adopted strategy is to apply for local compensation: a failed cavity is compensated by several neighboring cavities. Beam dynamics studies and method developments to apply such a failure compensation scheme are here reviewed. First simulation results for superconducting linac retuning and potential future improvements will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB191

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paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 20 August 2021

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MOPAB200

Parameters Measurements of Proton Beam Extracted from CSNS/RCS

target, MMI, neutron, extraction

668

Z.P. Li, Y.W. An, M.Y. Huang
IHEP, Beijing, People’s Republic of China
Y. Li, S.Y. Xu
DNSC, Dongguan, People’s Republic of China
H.Y. Liu
IHEP CSNS, Guangdong Province, People’s Republic of China

In order to study the emittance evolution of the circulating beam in the fast-cycling synchrotron (RCS) of the Chinese Spallation Neutron Source (CSNS), parameter measurements of the beam extracted at different times were carried out. The measurements were mainly based on wire-scanners mounted in RCS to target transport line (RTBT) for beam profile measurement, and different methods were applied in the solution processes. The emittance and C.S parameters of the extracted beam at different times were obtained and studied, which provided an important reference basis for the beam commissioning of RCS. The beam envelope along the RTBT has been matched and re-measured, which was in good agreement with the design optics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB200

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paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 25 August 2021

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MOPAB205

Minerva (MYRRHA Phase 1) RFQ Beam Commissioning

rfq, LEBT, MMI, linac

675

A. Gatera, J. Belmans, F. Davin, W. De Cock, F. Doucet, L. Parez, F. Pompon, A. Ponton, D. Vandeplassche
SCK•CEN, Mol, Belgium
F. Bouly
LPSC, Grenoble Cedex, France
C. Joly, L. Perrot
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
H. Podlech
IAP, Frankfurt am Main, Germany
J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
C. Zhang
GSI, Darmstadt, Germany

Funding: Part of this work was supported by the European Commission Framework Programme H₂020, MYRTE project nr. 662186
The MYRRHA project aims at coupling a 600 MeV proton accelerator to a subcritical fission core operating at a thermal power of 60 MW. The nominal proton beam for this ADS has an intensity of 4 mA and is delivered in a quasi-CW mode. Phase 1 of the project will realize a 100 MeV, 4 mA superconducting linac with the mission of ensuring the ADS requirements in terms of reliability and fault tolerance. As part of the reliability optimization program the integrated prototyping of the MINERVA injector is ongoing. The front-end of the injector is composed of an ECR proton source, a 2.6 m long LEBT (low energy beam transport line) and a four-rod RFQ accelerating the beam to 1.5 MeV. The present contribution focuses on the current beam tests on the RFQ, including beam matching, RF conditioning, assessment of the cavities’ performances and accelerated beam characterisation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB205

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paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 24 August 2021

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MOPAB207

Design Guideline for Minimizing Space-Charge-Induced Emittance Growth

rfq, proton, space-charge, linac

682

C. Zhang
GSI, Darmstadt, Germany

Space-charge-induced emittance growth is a big concern for designing low-energy and high-intensity linacs. The Equipartitioning Principle was introduced to minimize space-charge-induced emittance growth by removing free energy between the transverse and longitudinal degrees of freedom. In this study, a different design guideline is being proposed. It suggests holding the ratio of longitudinal emittance to transverse emittance around one and take advantage of low emittance transfer for minimizing emittance growth. Using a high-intensity RFQ accelerator as an example, a comparison between the two design methods has been made.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB207

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paper received ※ 17 May 2021 paper accepted ※ 21 May 2021 issue date ※ 01 September 2021

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MOPAB212

3-D Quantum Lifetime

simulation, electron, damping, radiation

700

H. Zhao, M. Blaskiewicz
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The quantum lifetime of electron beam in storage rings is defined by the particle loss that caused by the aperture limitation. Based on the equilibrium beam distribution produced by radiation damping and quantum excitation, the 1-d quantum lifetime has been well studied by A. Piwinski. In this paper, we give the derivation of the 3-d quantum lifetime, which can be applied to the machines with elliptical aperture and momentum acceptance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB212

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paper received ※ 04 June 2021 paper accepted ※ 21 June 2021 issue date ※ 16 August 2021

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MOPAB216

20-24 GeV FFA CEBAF Energy Upgrade

linac, booster, lattice, optics

715

S.A. Bogacz, J.F. Benesch, R.M. Bodenstein, B.R. Gamage, G.A. Krafft, V.S. Morozov, Y. Roblin
JLab, Newport News, Virginia, USA
J.S. Berg, S.J. Brooks, D. Trbojevic
BNL, Upton, New York, USA
D. Douglas
Douglas Consulting, York, Virginia, USA
G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
A proposal was formulated to increase the CEBAF energy from the present 12 GeV to 20-24 GeV by replacing the highest-energy arcs with Fixed Field Alternating Gradient (FFA) arcs. The new pair of arcs would provide six or seven new beam passes, going through this magnet array, allowing the energy to be nearly doubled using the existing CEBAF SRF cavity system. One of the immediate accelerator design tasks is to develop a proof-of-principle FFA arc magnet lattice that would support simultaneous transport of 6-7 passes with energies spanning a factor of two. We also examine the possibility of using combined function magnets to configure a cascade, six-way beam split switchyard. Finally, a novel multi-pass linac optics based on a weakly focusing lattice is being explored.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB216

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 29 August 2021

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MOPAB220

Towards Deterministic Design of MBA-Lattices

dipole, lattice, quadrupole, sextupole

722

B.C. Kuske
HZB, Berlin, Germany

Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of the Helmholtz Association
Since the pioneering work of MAX IV *, multi-bend achromat (MBA) lattices have become the standard in lattice design for 4th generation lights sources as well as upgrades of 3rd generation storage rings. The distribution of the bending angle to many weak dipoles enables to reach unprecedented low emittance and highest brightness. In their most basic form, MBA-lattices consist of a repetitive unit cell and two identical matching cells on either end of the achromatic arc. The simplicity of both cells allows for a unique determination of the linear lattice parameters in dependence on boundary conditions defined by the design goals. Those might be the emittance, momentum compaction factor, chromaticity, as well as phase advances with respect to achieving higher-order achromatic structures. A scan of optional lattice prototypes is quickly obtained. We demonstrate this concept and apply it in the design of the first candidates for the lattice of BESSY III, a green-field 4th generation storage ring being currently planned at HZB, Berlin, Germany.
* https://www.maxiv.lu.se/accelerators-beamlines/accelerators/accelerator-documentation/max-iv-ddr/

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB220

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paper received ※ 17 May 2021 paper accepted ※ 23 July 2021 issue date ※ 26 August 2021

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MOPAB225

A HMBA Lattice Design Study for the 4 GeV Light Source

lattice, storage-ring, dipole, sextupole

734

S.W. Jang, E.-S. Kim
KUS, Sejong, Republic of Korea

The 4th generation storage ring (4GSR) project will start from 2022 in South Korea. We proposed HMBA (Hybrid Multi-Bend Achromatic) lattice for 4GSR with super-bend at the center of the lattice. The 4GSR lattice is designed to combined HMBA lattice with a 4 GeV, 53 pm-rad emittance and 843m. The storage ring including 32 long with 5.65m, 16 short straight with 1.3m sections for IDs and 16 super-bend sections for more different type of beam line experiments. A calculated dynamic aperture is more larger than 15mm in both direction and the beam life time is expected to 4.7 hour. In this paper, we will describe the study results of the HMBA lattice design with a 4GeV light source.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB225

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paper received ※ 20 May 2021 paper accepted ※ 24 May 2021 issue date ※ 30 August 2021

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MOPAB235

Transverse 2d Phase-Space Tomography Using Beam Position Monitor Data of Kicked Beams

optics, electron, betatron, storage-ring

763

K. Hwang, C.E. Mitchell, R.D. Ryne
LBNL, Berkeley, California, USA

Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The time-series Beam Position Monitor (BPM) data of kicked beam is a function of lattice parameters and beam parameters including phase-space density. The decoherence model using the first-order detuning parameter has an exact solution when the beam is Gaussian. We parameterize the beam phase-space density by multiple Gaussian kernels of different weights, means, and sizes to formulate the inverse problem for 2D phase-space tomography. Numerical optimization and Bayesian inference are used to infer the beam density.

Poster MOPAB235 [1.253 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB235

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paper received ※ 20 May 2021 paper accepted ※ 02 June 2021 issue date ※ 01 September 2021

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MOPAB236

Ion Beam Dynamics in Linac-100 Facility at Jinr

linac, cavity, acceleration, rfq

767

S.M. Polozov, V.S. Dyubkov, Y. Lozeev, T.A. Lozeeva, A.V. Samoshin
MEPhI, Moscow, Russia

The heavy-ion linac LINAC-100 is a superconducting driver-accelerator proposed as one of the prospective projects at JINR. Its goal is to accelerate primary stable isotope CW high-intensity beams to energies up to 100 MeV/u*. This linac is discussed as the first stage of a new rare isotope facility DERICA (Dubna Electron-Radioactive Ion Collider fAcility), being under development at JINR since 2017**. LINAC-100 is supposed to work with a wide range of beams with A/Z 3.5/7, Uranium U³⁴⁺ being the heaviest. Its concept has undergone many changes, mostly considering stripping cells to increase accelerator efficiency. During the latest investigations of various stripping cells [***, ****], Uranium beam stripping at the energy 10 MeV/u and utilizing three adjacent charge states 59-61+ resulted in 60% output beam intensity preservation (or 30 pA overall output current). The current layout of the LINAC-100 is the following: one or two (separately for light and heavy ions) normal conducting front-end linacs, gas stripper cell at 10 MeV/u, and the SC section. In this paper three charge state Uranium beam dynamics in the current version of SC LINAC-100 section is presented.
*S Polozov 2020 PhysScr 95 084006
**A S Fomichev Phys Usp 62(7) 675-690 2019
***Tolstikhina I 2018 Basic At Int of Acc H Ions in Matter 98 1
**** W Barth J Phys Conf Ser 1350:012096

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB236

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paper received ※ 20 May 2021 paper accepted ※ 17 August 2021 issue date ※ 26 August 2021

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MOPAB240

Estimates of Damped Equilibrium Energy Spread and Emittance in a Dual Energy Storage Ring

storage-ring, damping, photon, radiation

774

B. Dhital, G.A. Krafft
ODU, Norfolk, Virginia, USA
Y.S. Derbenev, D. Douglas, A. Hutton, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177 and DE-AC02-06CH11357. / Jefferson Lab EIC Fellowship2020.
A dual energy storage ring design consists of two loops at markedly different energies. As in a single-energy storage ring, the linear optics in the ring design may be used to determine the damped equilibrium emittance and energy spread. Because the individual radiation events in the two rings are different and independent, we can provide analytical estimates of the damping times in a dual energy storage ring. Using the damping times, the values of damped energy spread, and emittance can be determined for a range of parameters related to lattice design and rings energies. We present analytical calculations along with simulation results to estimate the values of damped energy spread and emittance in a dual energy storage ring. We note that the damping time tends to be dominated by the damping time of the high energy ring in cases where the energy of the high energy rings is significantly greater than that of the low energy ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB240

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paper received ※ 17 May 2021 paper accepted ※ 27 May 2021 issue date ※ 13 August 2021

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MOPAB242

A Six-Bend-Achromat Lattice for a 2.5 GeV Diffraction-Limited Storage Ring

lattice, quadrupole, storage-ring, dipole

782

J. Li, M. Abo-Bakr, P. Goslawski
HZB, Berlin, Germany
Z.H. Bai
USTC/NSRL, Hefei, Anhui, People’s Republic of China

HZB has proposed a 2.5 GeV diffraction-limited storage ring as the upgrade of BESSY II. A Six-Bend-Achromat lattice based on Higher-Order Achromat, as one of the possible solutions, has been designed to meet the requirements of low emittance, compact layout, large dynamic aperture and large momentum acceptance. The linear lattice design and the nonlinear performance are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB242

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paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 17 August 2021

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MOPAB245

Theoretical Analysis of the Conditions for an Isochronous and CSR-Immune Triple-Bend Achromat with Stable Optics

dipole, optics, radiation, synchrotron-radiation

786

C. Zhang, Y. Jiao
IHEP, Beijing, People’s Republic of China
C.-Y. Tsai
HUST, Wuhan, People’s Republic of China

Funding: National Natural Science Foundation of China (No. 11922512), Youth Innovation Promotion Association of Chinese Academy of Sciences (No. Y201904), National Key R&D Program of China (No. 2016YFA0401900)
Transport of high-brightness beams with minimum degradation of the phase space quality is pursued in modern accelerators. For the beam transfer line which commonly consists of bending magnets, it would be desirable if the transfer line can be isochronous and coherent synchrotron radiation (CSR)-immune. For multi-pass transfer line, the achromatic cell designs with stable optics would bring great convenience. In this paper, based on the transfer matrix formalism and the CSR point-kick model, we report the detailed theoretical analysis and derive the condition for a triple-bend achromat with stable optics in which the first-order longitudinal dispersion (i.e., R56) and the CSR-induced emittance growth can be eliminated. The derived condition suggests a new way of designing the bending magnet beamline that can be applied to the free-electron laser (FEL) spreader and energy recovery linac (ERL) recirculation loop.

Poster MOPAB245 [0.530 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB245

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paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 27 August 2021

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MOPAB246

Design of the MEBT for the JAEA-ADS Project

MEBT, linac, rfq, quadrupole

790

B. Yee-Rendón, Y. Kondo, F.M. Maekawa, S.I. Meigo, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan

The Medium Energy Beam Transport (MEBT) will transport a CW proton beam with a current of 20 mA and energy of 2.5 MeV from the exit of the normal conducting Radiofrequency Quadrupole (RFQ) to the superconducting Half-Wave resonator (HWR) section. The MEBT must provide a good matching between the RFQ and HWR, effective control of the emittance growth and the halo formation, enough space for all the beam diagnostics devices, among others. This work reports the first lattice design and the beam dynamics studies for the MEBT of the JAEA-ADS.

Poster MOPAB246 [0.827 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB246

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paper received ※ 10 May 2021 paper accepted ※ 02 June 2021 issue date ※ 19 August 2021

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MOPAB257

Effects of Mode Launcher on Beam Dynamics in Next Generation High Brightness C-Band Guns

gun, simulation, electron, cathode

813

A. Giribono, D. Alesini, F. Cardelli, G. Di Raddo, M. Ferrario, A. Gallo, J. Scifo, C. Vaccarezza, A. Vannozzi
INFN/LNF, Frascati (Roma), Italy
G. Castorina
AVO-ADAM, Meyrin, Switzerland
L. Ficcadenti
INFN-Roma, Roma, Italy
G. Muti
Sapienza University of Rome, Rome, Italy
G. Pedrocchi
SBAI, Roma, Italy

High-brightness RF photo-injectors plays nowadays a crucial role in the fields of radiation generation and advanced acceleration schemes. A high gradient C-band photoinjector consisting of a 2.5 cell gun followed by TW sections is here proposed as an electron source for radiation user facilities. The paper reports on beam dynamics studies in the RF injector and illustrates the effects on the beam quality of the mode launcher with a focus on the compensation of the quadrupole RF components.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB257

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paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 16 August 2021

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MOPAB262

First Thoughts on Lattices for a possible Metrology Light Source 2

lattice, dipole, sextupole, radiation

833

M. Arlandoo, M. Abo-Bakr, P. Goslawski, J. Li
HZB, Berlin, Germany

The Physikalisch-Technische Bundesanstalt (PTB), in cooperation with the Helmholtz-Zentrum Berlin (HZB), operates the Metrology Light Source (MLS), which is a low-energy electron storage ring. The MLS can be operated in a low-alpha mode to produce coherent synchroton ration in the far-IR and THz spectral range. In the scope of the Conceptual Design process for a BESSY II successor, the PTB also requested for an MLS successor to cover their increasing demands on synchrotron radiation. A combination of two different machines, one optimized for low emittance (BESSY III) and one for flexible timing capabilities (MLS II), would provide best radiation capabilities for our user community. In this paper, we discuss the demands on the MLS II and propose first lattice candidates which may meet the needs of the PTB and HZB. Currently, we focus on linear lattices for standard user mode with first steps towards nonlinear optimization.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB262

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paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 17 August 2021

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MOPAB264

Commissioning of the DESIR High-Resolution Separator at CENBG

multipole, MMI, dipole, quadrupole

841

J. Michaud, P. Alfaurt, A. Balana, B. Blank, L. Daudin, T. Kurtukian-Nieto, S. Leblanc, L.S. Serani
CENBG, Gradignan, France
F. Méot
BNL, Upton, New York, USA
F. Varenne
GANIL, Caen, France

DESIR is the low-energy part of the SPIRAL2 ISOL facility under construction at GANIL. The high-resolution mass separator (HRS) included in DESIR is a 180 degree symmetric online separator with two 90 degree magnetic dipole sections arranged with electrostatic quadrupoles, sextupoles and a multipole on the mid plane. The HRS is now completely mounted at CENBG and under commissioning for the next 2 to 3 years before its transfer at the entrance of the DESIR facility. The objective is to test, characterise and correct all HRS elements contributing to the higher order aberration by performing experimental measurements and comparing them with the results from different simulation tools. The recently mounted pepperpot-type emittance-meter will allow us to observe the emittance figures and dynamically tune the multipole to improve the optical parameters of the HRS. We will present the first results concerning the hexapolar correction with the multipole, the associated emittance measurements and the resolution currently achieved.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB264

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paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 10 August 2021

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MOPAB268

Design of a Continuous Wave Heavy Ion RFQ for BISOL

rfq, ISOL, LEBT, linac

851

S. Liu, M.Y. Han, Y.R. Lu, Q.Y. Tan, Z. Wang
PKU, Beijing, People’s Republic of China

The Beijing isotope separation online (BISOL) facility will be used to study the new physics and technologies at the limit of the nuclear stability. The post accelerator for BISOL facility aims to accelerate radioactive beams to 150MeV/u. As an injector for the downstream superconducting linac, a 4-vane RFQ operating at 81.25MHz is needed to accelerate high-charge-state ions such as 132Sn²²⁺ from 3keV/u to 500keV/u in CW mode. We have compared two kinds of beam dynamics of BISOL RFQ with and without a Multi-Harmonic Buncher (MHB) bunching the continuous wave beam up-stream of the RFQ. The results indicate that it is possible to keep transverse emittance growth within tolerable limits while the longitudinal emittance is much smaller than the design without an external buncher. The acceleration of multi-charge beams simultaneously in the RFQ is also discussed in this paper.

Poster MOPAB268 [1.829 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB268

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paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 16 August 2021

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MOPAB270

Beam Dynamics Studies in a Standing Wave Ka-band Linearizer

electron, bunching, operation, simulation

857

J. Scifo, M. Behtouei, L. Faillace, M. Ferrario, A. Giribono, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
M. Migliorati
INFN-Roma1, Rome, Italy
M. Migliorati
Sapienza University of Rome, Rome, Italy
G. Torrisi
INFN/LNS, Catania, Italy

Next-generation FEL user facilities require high-quality electron beams with kA peak current. The combination of a high brightness RF injector and a magnetic compression stage represents a very performant solution in terms of electron beam emittance and peak current. One of the important issues is the design of a proper device that acts as a linearizer for the beam longitudinal phase space. Recently, the design of a SW Ka band RF accelerating structure has been proposed with promising results. The paper reports on electron beam dynamics studies in the described RF structure.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB270

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paper received ※ 19 May 2021 paper accepted ※ 29 August 2021 issue date ※ 26 August 2021

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MOPAB277

Installation, Use and Follow-Up of an Emittance-Meter at the Arronax Cyclotron 70XP

cyclotron, injection, quadrupole, ECR

877

F. Poirier, R. Bellamy, F. Bulteau-Harel, C. Castel, T. Durand, X. Goiziou, F. Haddad, C. Koumeir, R. Lelièvre, G. Mechin, L. Perrigaud, J. Poudevigne, H. Trichet
Cyclotron ARRONAX, Saint-Herblain, France
T. Adam, P.G. Graehling, M. Heine, C. Maazouzi, F.R. Osswald, E.K. Traykov
IPHC, Strasbourg Cedex 2, France
A. Dinkov, S. Wurth
IJCLab, ORSAY, France
F. Haddad
SUBATECH, Nantes, France

Funding: This work is supported by grants from the ANR program "Investissements d’Avenir", n°ANR-11-EQPX-0004, n°ANR-11-LABX-18-01 and n°ANR-16-IDE-0007 and by a PhD scholarship from CNRS/IN2P3.
The 70 MeV cyclotron group of the Arronax GIP (Interest Public Group), France, foresees to increase its beam intensity on target. For this, several beam studies are being performed in the various sections of the accelerator including the injection. Thus, an Allison-type emittance-meter has been installed in this section above the cyclotron and downstream a quadrupole triplet. Installation and the first results of a campaign of measurements are presented including high intensity runs, up to 1 mA for 40 keV H⁻ ions. The emittance-meter is expected to be used with several accelerators throughout the world. Therefore, a strategy on the follow-up of the activation of sample materials used in the equipment is being established and is described in the paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB277

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paper received ※ 17 May 2021 paper accepted ※ 27 May 2021 issue date ※ 12 August 2021

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MOPAB289

Machine Learning Training for HOM reduction and Emittance Preservation in a TESLA-type Cryomodule at FAST

HOM, cavity, electron, controls

916

J.A. Diaz Cruz
UNM-ECE, Albuquerque, USA
J.A. Diaz Cruz, A.L. Edelen, B.T. Jacobson, J.P. Sikora
SLAC, Menlo Park, California, USA
D.R. Edstrom, A.H. Lumpkin, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

Low emittance electron beams are of high importance at facilities like the LCLS-II at SLAC. Emittance dilution effects due to off-axis beam transport for a TESLA-type cryomodule (CM) have been shown at the Fermilab Accelerator Science and Technology facility. The results showed the correlation between the electron beam-induced cavity high-order modes (HOMs) and submacropulse centroid slewing and oscillation downstream of the CM. Mitigation of emittance dilution can be achieved by reducing the HOM signals and the variances in the submacropulse beam positions downstream of the CM. Here we present a Machine Learning based optimization and model construction for HOM signal level reduction using Neural Networks and Gaussian Processes. To gather training data we performed experiments using single bunch and 50 bunch electron beams with charges up to 125 pC/b. We measured HOM signals of all cavities and beam position with a set of BPMs downstream of the CM. The beam trajectory was changed using V/H125 corrector set located upstream of the CM. The results presented here will inform the LCLS-II injector commissioning and will serve as a prototype for HOM reduction and emittance preservation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB289

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 14 August 2021

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MOPAB295

Simulation Study of Emittance Measurement Using a Genetic Algorithm for Space Charge Dominated Beams

quadrupole, space-charge, simulation, lattice

935

H.D. Zhang, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom

Funding: This work was supported by the HL-LHC-UK phase II project funded by STFC under Grant Ref: ST/T001925/1 under and the STFC Cockcroft core grant No. ST/G008248/1.
The quadrupole scan method is one of the traditional ways to measure beam emittance in an accelerator. The required devices are simple: several quadrupole magnets and a beam profile monitor. Beam sizes are measured from the beam profile monitor with different quadrupole settings to bring the beam through its waist and then fitted to a quadratic equation to determine the Twiss parameters. measured data from a quadrupole scan taking the beam through its waist is fitted to a quadratic equation and this allows determining the Twiss parameters. However, with increasing beam intensity, the transfer function becomes non-linear and this causes a deviation of the fitted emittance from its real value, making it no longer useful. In this contribution, a genetic algorithm is applied to find the optimum quadrupole scan fit in space-charge dominated electron beams. Results from simulations using different space charge levels are presented and scenarios identified where this method can be applied.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB295

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paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 02 September 2021

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MOPAB303

Design of the X-Ray Beam Size Monitor for the Advanced Photon Source Upgrade

electron, photon, detector, storage-ring

956

K.P. Wootton, F.K. Anthony, K. Belcher, J.S. Budz, J. Carwardine, W.X. Cheng, S. Chitra, G. Decker, S.J. Izzo, S.H. Lee, J. Lenner, Z. Liu, P. McNamara, H.V. Nguyen, F.S. Rafael, C. Roehrig, J. Runchey, N. Sereno, G. Shen, J.B. Stevens, B.X. Yang
ANL, Lemont, Illinois, USA

Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
A beam size monitor provides an intuitive display of the status of the beam profile and motion in an accelerator. In the present work, we outline the design of the X-ray electron beam size monitor for the Advanced Photon Source Upgrade. Components and anticipated performance characteristics of the beam size monitor are outlined.

Poster MOPAB303 [0.577 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB303

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paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021

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MOPAB304

Beam Diagnostics for Multi-Objective Bayesian Optimization at the Argonne Wakefield Accelerator Facility

diagnostics, dipole, quadrupole, wakefield

960

J.P. Gonzalez-Aguilera, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
W. Liu, P. Piot, J.G. Power, E.E. Wisniewski
ANL, Lemont, Illinois, USA
R.J. Roussel
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA

Particle accelerators must achieve certain beam quality objectives for use in different experiments. Usually, optimizing certain beam objectives comes at the expense of others. Additionally, there are many input parameters and a limited number of diagnostics. Therefore, accelerator tuning becomes a multi-objective optimization problem with a limited number of observations. Multi-objective Bayesian optimization was recently proposed as an efficient method to find the Pareto front for an online accelerator tuning problem with reduced number of observations. In order to experimentally test the multi-objective Bayesian optimization method, a novel accelerator diagnostic is being designed to measure multiple beam quality metrics of an electron beam at the Argonne Wakefield Accelerator Facility. Here, we present a design consisting in a pepper-pot mask, a dipole magnet and a scintillation screen, which allows a simultaneous measurement of the electron beam energy spread and vertical emittance. Additionally, a surrogate model for the vertical emittance was constructed with only 60 observations and without prior knowledge of the objective function nor diagnostics constraints.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB304

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paper received ※ 18 May 2021 paper accepted ※ 08 June 2021 issue date ※ 26 August 2021

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MOPAB310

Vertical Phase Space Measurement Progress at Canadian Light Source

electron, lattice, synchrotron, experiment

963

Y. Yousefi Sigari, D. Bertwistle, M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada
M.J. Boland
University of Saskatchewan, Saskatoon, Canada

A key feature of third-generation light sources is their small vertical opening angle, which is difficult to measure experimentally. To reconstruct the vertical phase space, one can scan the beam’s position using X-ray synchrotron radiation (XSR) and a pinhole camera. The XSR diagnostic beamline, operational in the wavelength region of 0.05 - 0.15 nm, in Canadian Light Source (CLS) is qualified to measure the beam position with X-ray radiation. Using the corrector magnets in CLS lattice made of 12 identical double-bend achromats (DBA) cells, vertical iterations can be executed parallel to the beam’s original orbit. The outcomes of this experiment are: 1) the vertical beam positions that are monitored by BPMs, and 2) the X-ray image of the beam that is projected through the pinhole. The bumps were simulated using Matlab Middle Layer (MML) for Accelerator control systems to get an insight of the source point’s position in the XSR’s bending magnet. The simulation shows the position of the source point depends on which corrector sets are chosen.

Poster MOPAB310 [0.328 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB310

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paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 13 August 2021

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MOPAB318

Beam Characterization of Five Electrode ECR Ion Source

ECR, ECRIS, plasma, experiment

980

H.M. Kewlani, S. Gharat, S. Krishnagopal, J.V. Mathew, S.V.L.S. Rao
BARC, Mumbai, India
B. Dikshit, H.M. Kewlani, S. Krishnagopal
Homi Bhbha National Institute (HBNI), DAE, Mumbai, India

A five electrode ECR Ion Source (ECRIS) was developed for the Low Energy High-Intensity Proton Accelerator (LEHIPA) at BARC. The ECRIS is operated at the energy of 50 keV with a beam current of 20 mA. The ECRIS characterization is done for the beam current, beam emittance, and proton fraction in continuous and pulse beam operation. The pulsed beam operation of the ion source starting from 500 µs to 200 ms of pulse on time with a repetition rate of 1 to 10 Hz. The transverse beam emittance measurement is done by using an Allison scanner. The beam emittance characterization experiments are conducted by varying applied microwave power to the plasma, operating gas pressure of plasma and puller voltage. The measured beam emittance is in the range of 0.3 pi.mm. mrad to 0.4 pi.mm. mrad for 50 keV beam. In this paper beam emittance experiment setup and results are discussed.

Poster MOPAB318 [2.496 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB318

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paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 16 August 2021

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MOPAB325

Development of Bunch Width Monitor with High Time Resolution for Low Emittance Muon Beam in the J-PARC Muon g-2 / EDM Experiment

experiment, acceleration, linac, laser

1004

M. Yotsuzuka, T. Iijima, K. Inami, Y. Sue, K. Sumi
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
T. Iijima
KMI, Nagoya, AIchi Prefecture, Japan
Y. Kondo
JAEA, Ibaraki-ken, Japan
T. Mibe
KEK, Tsukuba, Japan
Y. Nakazawa
Ibaraki University, Ibaraki, Japan
M. Otani, N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Takeuchi
Kyushu University, Fukuoka, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan

The J-PARC muon g-2/EDM experiment plans to measure the muon anomalous magnetic moment and electric dipole moment sensitive to new physics with high precision. This experiment uses a novel method using the low-emittance muon beam achieved by cooling and re-acceleration. In the muon linac consisting of four different accelerating cavities, the main cause of the emittance growth is the beam mismatch between the different cavities. Especially for the cavity in the low-beta section (ß=0.08-0.27), the longitudinal acceptance is narrow and beam mismatch has a significant impact. In order to perform beam matching in the low-beta cavity, a new beam monitor that can measure the low-emittance muon beam with high time resolution is required. Therefore, we developed a bunch width monitor (BWM) using a microchannel plate. The time resolution of the BWM was measured to be 40 picoseconds on the test bench using a picosecond pulse laser. It means that the BWM is possible to perform diagnosis with a phase accuracy of 1% for the acceleration phase of 324 MHz. We also evaluated factors that limit the current time resolution. In this presentation, the results of an evaluation of the BWM are reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB325

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paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 10 August 2021

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MOPAB326

Maximum Entropy Reconstruction of 4D Transverse Phase Space from 2D Projections: with Application to Laser Wire Measurements in the SNS HEBT

laser, neutron, coupling, linac

1008

C.Y. Wong, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

We employ the principle of maximum entropy (MENT) to reconstruct 4D transverse phase space from its 2D projections. Emittance devices commonly measure two specific 2D projections, i.e. the horizontal and vertical phase space distributions. We show that: 1) given only these two 2D projections, their product is the analytic MENT solution to the 4D distribution; and 2) additional 2D projections provide information on inter-plane coupling in the MENT reconstruction of the 4D phase space which can be solved numerically. At the Spallation Neutron Source (SNS), laser wires in the high energy beam transport (HEBT) enable non-invasive two-slit type transverse phase space measurements. Laser wires play the role of the first slit whereas physical wires downstream of a drift act as the second slit. We reconstruct the 4D phase space in the HEBT using all four horizontal/vertical permutations of the two slits where: 1) the two configurations with parallel slits constitute ordinary 2D phase space measurements in either plane; and 2) the two configurations with perpendicular slits carry coupling information.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB326

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paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 17 August 2021

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MOPAB404

A Low Emittance Compact Proton Injector for a Proton Therapy Facility

proton, ion-source, LEBT, rfq

1218

S.X. Peng, J.E. Chen, B.J. Cui, Z.Y. Guo, Y.X. Jiang, K. Li, T.H. Ma, J. Sun, W.B. Wu, A.L. Zhang, J.F. Zhang
PKU, Beijing, People’s Republic of China
Y.H. Pu
Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China

To meet the requirements of a Proton Therapy Facility funded by the National Key Research and Development Program of China, a new compact ion source-LEBT integrated proton injector was developed at Peking University (PKU). It consists of a typical PKU permanent magnet compact 2.45 GHz ECR ion source (PMECRIS) and an electrostatic LEBT with an electrostatic lens, a beam chopper, a set of beam steers, an ACCT, a bellow, an e-trap, and a valve. A 1000 L/s molecular pump is adopted to maintain the vacuum for this integrated injector. The length from RF matching plane to RFQ front flange is about 450 mm. Chopper is used to shorten the pulse length from ms to µs with sharp edges. Test results of this PMECR source prove that it has the ability to deliver a proton beam with a current from 10 mA to 90 mA with a duty factor of 3%(100Hz/0.3ms) and its RMS emittance less than 0.1 mm·mrad at 30 keV. The acceptance tests of this integrated injector have been performed with a 30 keV hydrogen beam. A required proton current of 18 mA with ripple wave less than 0.1 mA successfully passed through a 20 mm aperture diaphragm at RFQ entrance flange. Its rms emittance is about 0.06 mm·mrad.

Poster MOPAB404 [1.946 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB404

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paper received ※ 19 May 2021 paper accepted ※ 17 August 2021 issue date ※ 18 August 2021

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TUXA01

Advances in Understanding of Ion Effects in Electron Storage Rings

simulation, ion-effects, storage-ring, injection

1267

J.R. Calvey, M. Borland, T.K. Clute, J.C. Dooling, L. Emery, J. Gagliano, J.E. Hoyt, P.S. Kallakuri
ANL, Lemont, Illinois, USA

Ion instability, in which beam motion couples with trapped ions in an accelerator, is a serious concern for high-brightness electron storage rings. For the APS-Upgrade, we plan to mitigate coherent ion instability using a compensated gap scheme. To study incoherent effects (such as emittance growth), an IONEFFECTS element has been incorporated into the particle tracking code ELEGANT. The simulations include multiple ionization, transverse impedance, and charge variation between bunches. Once these effects are included, the simulations show good agreement with measurements at the present APS. We have also installed a gas injection system, which creates a controlled pressure bump of Nitrogen gas in a short section of the APS ring. The resulting ion instability was studied under a wide variety of beam conditions. For cases with no or insufficient train gaps, large emittance growth was observed. IONEFFECTS simulations of the gas injection experiment and APS-U storage ring show the possibility of runaway emittance blowup, where the blown-up beam traps more ions, driving further instability.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXA01

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paper received ※ 24 June 2021 paper accepted ※ 27 July 2021 issue date ※ 10 August 2021

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TUXA07

Beam Dynamics Study in a Dual Energy Storage Ring for Ion Beam Cooling*

storage-ring, cavity, electron, focusing

1290

B. Dhital, G.A. Krafft
ODU, Norfolk, Virginia, USA
Y.S. Derbenev, D. Douglas, A. Hutton, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: * Work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177 and DE-AC02-06CH11357. / Jefferson Lab EIC Fellowship2020.
A dual energy storage ring designed for beam cooling consists of two closed rings with significantly different energies: the cooling and damping rings. These two rings are connected by an energy recovering superconducting RF structure that provides the necessary energy difference. In our design, the RF acceleration has a main linac and harmonic cavities both running at crest that at first accelerates the beam from low energy E_L to high energy E_H and then decelerates the beam from E_H to E_L in the next pass. The purpose of the harmonic cavities is to extend the bunch length in a dual energy storage ring as such a longer bunch length may be very useful in a cooling application. Besides these cavities, a bunching cavity running on zero-crossing phase is used outside of the common beamline to provide the necessary longitudinal focusing for the system. In this paper, we present a preliminary lattice design along with the fundamental beam dynamics study in such a dual energy storage ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXA07

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paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 28 August 2021

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TUPAB002

Round Colliding Beams: Successful Operation Experience

luminosity, collider, solenoid, beam-beam-effects

1326

D.B. Shwartz, O.V. Belikov, D.E. Berkaev, D.B. Burenkov, V.S. Denisov, A.S. Kasaev, A.N. Kirpotin, S.A. Kladov, I. Koop, A.A. Krasnov, A.V. Kupurzhanov, G.Y. Kurkin, M.A. Lyalin, A.P. Lysenko, S.V. Motygin, E. Perevedentsev, V.P. Prosvetov, Yu.A. Rogovsky, A.M. Semenov, A.I. Senchenko, L.E. Serdakov, D.N. Shatilov, P.Yu. Shatunov, Y.M. Shatunov, M.V. Timoshenko, I.M. Zemlyansky, Yu.M. Zharinov
BINP SB RAS, Novosibirsk, Russia
S.A. Kladov, I. Koop, A.A. Krasnov, M.A. Lyalin, E. Perevedentsev, Yu.A. Rogovsky, Y.M. Shatunov, D.B. Shwartz
NSU, Novosibirsk, Russia

VEPP-2000 electron-positron collider operating in the beam energy range of 150-1000 MeV is the only machine originally designed for and successfully exploiting Round Beams Concept. After injection chain upgrade including link to the new BINP injection complex VEPP-2000 proceeded with data taking since 2017 with luminosity limited only by beam-beam effects. At the low energies (300-600 MeV/beam) the novel technique of effective emittance controlled increase by weak coherent beam shaking allowed to suppress the limiting flip-flop effect and resulted in additional luminosity gain factor of 4. The averaged delivered luminosity at the omega-meson production energy (2*391 MeV) achieved L = 2*10³¹cm^-2s⁻¹/IP. At the top energies above nucleon-antinucleon production threshold the stable operation with luminosity of L = 5*10³¹cm^-2s⁻¹/IP resulted in high average data taking rate of 2 pb^-1/day in 2020.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB002

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paper received ※ 20 May 2021 paper accepted ※ 07 June 2021 issue date ※ 31 August 2021

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TUPAB004

Comparison of Accelerator Codes for Simulation of Lepton Colliders

radiation, lattice, optics, lepton

1334

L. van Riesen-Haupt, H. Burkhardt, T.H.B. Persson, R. Tomás García
CERN, Meyrin, Switzerland

This paper compares simulation results obtained with SAD, MAD-X and the PTC implementation in MADX for the design studies of the FCC-ee. On-momentum and off-momentum optics are explored for the various programs. Particle tracking with and without synchrotron radiation are used to compare amplitude detuning and emittance. Finally, this paper outlines how well-established SAD features such as tapering have recently been integrated into MADX.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB004

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paper received ※ 16 May 2021 paper accepted ※ 15 June 2021 issue date ※ 26 August 2021

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TUPAB005

Emittance Estimates for the Future Circular Collider

quadrupole, alignment, simulation, sextupole

1338

L. van Riesen-Haupt, T.K. Charles, R. Tomás García, F. Zimmermann
CERN, Meyrin, Switzerland
T.K. Charles
The University of Liverpool, Liverpool, United Kingdom

The alignment strategy of the FCC-ee has a large impact on its luminosity. Larger alignment tolerances result in increased coupling and a subsequently higher vertical emittance. At the same time, tighter alignment tolerances around the 100 km ring are a major cost driver. This paper applies analytical emittance estimate methods to the FCC-ee and compares their predictions to data from simulations with different alignment tolerances. These methods can be used to help understand the impact of misalignments of certain magnet groups and to come up with an efficient alignment strategy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB005

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paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 26 August 2021

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TUPAB007

A Correction Scheme for the Magnet Imperfection on the CEPC Collider Ring

lattice, quadrupole, alignment, optics

1346

B. Wang, Y. Wang, Y. Wei, C.H. Yu, Y. Zhang
IHEP, Beijing, People’s Republic of China

This paper describes the error correction scheme for the CEPC CDR lattice in Higgs mode, which has a small beta function at the interaction point. The low emittance optics has an enhanced sensitivity to the magnet misalignments and field errors, especially for the final focus quadrupole misalignment. The magnet imperfection will cause the closed orbit distortion and optics distortion. The correction scheme for these magnet imperfections includes the closed orbit correction, the dispersion correction, the beta function correction and the betatron coupling correction. The resulting performance and the dynamic aperture for the corrected lattice are studied.

Poster TUPAB007 [1.075 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB007

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paper received ※ 14 May 2021 paper accepted ※ 09 June 2021 issue date ※ 14 August 2021

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TUPAB023

Design Considerations of a High Intensity Booster for PETRA IV

lattice, injection, booster, extraction

1386

H.C. Chao, I.V. Agapov, S.A. Antipov
DESY, Hamburg, Germany

A 6 GeV booster lattice with a high intensity capacity for the PETRA IV project is presented. Firstly the requirements and constraints are articulated. Due to the geometric constraints the ring will be installed in racks mounted on ceilings. Then following some design strategies of reaching high intensity limit, a lattice is designed and presented. The topics covering the linear optics, nonlinear dynamics, orbit correction, orbit bump, and some instability studies are investigated.

Poster TUPAB023 [0.975 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB023

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paper received ※ 11 May 2021 paper accepted ※ 11 June 2021 issue date ※ 12 August 2021

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TUPAB024

Lattice Options Comparison for a DLSR Injector

lattice, injection, booster, synchrotron

1390

H.C. Chao, I.V. Agapov, S.A. Antipov
DESY, Hamburg, Germany

DESY IV, as a part of the injector chain, must have lower emittance for PETRA IV injection. Depending on the scenarios of the injector, two lattice options for DESY IV are presented. They are designed for different purposes. The first option comes with a high momentum compaction factor with acceptable emittance. It is designed to be a full intensity booster. The other option is with low emittance dedicated to be an accumulator at high energies. The general beam dynamics properties are simulated and discussed. Their strengths and weaknesses are compared.

Poster TUPAB024 [0.751 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB024

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paper received ※ 11 May 2021 paper accepted ※ 09 June 2021 issue date ※ 31 August 2021

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TUPAB034

Development of Multi-Alkali Antimonides Photocathodes for High-Brightness RF Photoinjectors

cathode, electron, site, laser

1416

S.K. Mohanty, M. Krasilnikov, A. Oppelt, H.J. Qian, F. Stephan
DESY Zeuthen, Zeuthen, Germany
G. Guerini Rocco, C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
P. Michelato, L. Monaco, D. Sertore
INFN/LASA, Segrate (MI), Italy

Multi-alkali antimonide-based photocathodes are suitable candidate for the electron sources of next-generation high brightness RF photoinjectors due to their excellent photoemissive properties especially, like low thermal emittances and high sensitivity to visible light. The former stands out, paving the way towards CW operations. Based on the previous successful development of Cesium Telluride photocathodes, we are now channelling our efforts toward an R&D activity focused on KCsSb and NaKSb(Cs) photocathodes. Parallel to that R&D activity, we have installed a new dedicated photocathode production system at the INFN-LASA to start the preparation of these photocathodes for their test in the PITZ photoinjector at DESY in Zeuthen. In this paper, detailed experimental results obtained from the KCsSb, along with a preliminary result from the NaKSb(Cs) photocathode material as well as the status of the overall project are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB034

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 31 August 2021

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TUPAB036

The Accelerator Design Progress for EIC Strong Hadron Cooling

electron, hadron, proton, linac

1424

E. Wang, S. Peggs, V. Ptitsyn, F.J. Willeke, W. Xu
BNL, Upton, New York, USA
S.V. Benson
JLab, Newport News, Virginia, USA
D. Douglas
Douglas Consulting, York, Virginia, USA
C.M. Gulliford, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
C.E. Mayes
Xelera Research LLC, Ithaca, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy,
The Electron-Ion Collider will achieve a luminosity of 10³⁴ cm^-2 s⁻¹ by incorporating strong hadron cooling to counteract hadron Intra-Beam Scattering, using a coherent electron cooling scheme. An accelerator will deliver the beams with key parameters, such as 1 nC bunch charge, and 1e-4 energy spread. The paper presents the design and beam dynamics simulation results. Methods to minimize beam noise, the challenges of the accelerator design, and the R&D topics being pursued are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB036

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paper received ※ 16 May 2021 paper accepted ※ 11 June 2021 issue date ※ 01 September 2021

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TUPAB049

USSR HMBA Storage Ring Lattice Options

injection, lattice, SRF, optics

1466

S.M. Liuzzo, N. Carmignani, L.R. Carver, J. Chavanne, L. Hoummi, J. Jacob, T.P. Perron, R. Versteegen, S.M. White
ESRF, Grenoble, France
I.A. Ashanin, V.S. Dyubkov, S.M. Polozov
MEPhI, Moscow, Russia
I.A. Ashanin, V.S. Dyubkov, T. Kulevoy, S.M. Polozov
NRC, Moscow, Russia
T. Kulevoy
ITEP, Moscow, Russia

Funding: European Union’s Horizon 2020 research and innovation program under grant #871072 Russian federation resolution #287
Several new accelerator facilities will be built in Russia in a few years from now. One of those facilities is a 6GeV storage ring (SR) light source (USSR - Ultimate Source of Synchrotron Radiation) to be built in Protvino, near Moscow. The Cremlin+ project aims to incorporate in this activity the best experience of European Accelerator Laboratories. The design of the optics for this SR is presented here in two declinations leading to 70 pm-rad equilibrium horizontal emittance. The first is a 40 cells lattice, the second is the same but includes high field Short Bending magnet sources in each cell. Optics and high order multipole optimizations are performed to obtain sufficient lifetime and dynamic aperture for a conservative off-axis injection.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB049

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paper received ※ 12 May 2021 paper accepted ※ 11 June 2021 issue date ※ 21 August 2021

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TUPAB051

Elettra and Elettra 2.0

insertion, insertion-device, status, coupling

1474

E. Karantzoulis, A. Carniel, D. Castronovo, S. Di Mitri, B. Diviacco, S. Krecic
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the future upgrade concerning the new ultra-low emittance light source Elettra 2.0 that will provide ultra-high brilliance while the very short pulses feasibility study for time resolved experiments is in progress.

Poster TUPAB051 [1.632 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB051

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paper received ※ 10 May 2021 paper accepted ※ 27 May 2021 issue date ※ 20 August 2021

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TUPAB054

CDR BASELINE LATTICE FOR THE UPGRADE OF SOLEIL

lattice, injection, photon, coupling

1485

A. Loulergue, D. Amorim, P. Brunelle, A. Gamelin, A. Nadji, L.S. Nadolski, R. Nagaoka, R. Ollier, M.-A. Tordeux
SOLEIL, Gif-sur-Yvette, France

Previous MBA studies converged toward a lattice composed of 20 7BA solution elaborated by adopting the sextupole pairing scheme with dispersion bumps originally developed at the ESRF-EBS. It provided a low natural horizontal emittance value of 70-80 pm-rad range at an energy of 2.75 GeV. Due to difficulties to accommodate such lattice geometry in the SOLEIL present tunnel as well as to preserve at best the beamline positioning, alternative lattice based on HOA (Higher-Order Achromat) type cell has been recently investigated. The HOA type cell being more modular and possibly exhibiting larger momentum acceptance as well as low emittances, a solution alternating 7BA and 4BA cells was then identified as the best to adapt the current beamline positioning. The SOLEIL CDR upgrade reference lattice is then composed of 20 HOA cells alternating 7BA and 4BA giving a natural horizontal emittance of 80 pm-rad. The linear and non-linear beam dynamic properties of the lattice along with the possibility of horizontal off-axis injection at full betatron coupling are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB054

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paper received ※ 21 May 2021 paper accepted ※ 02 July 2021 issue date ※ 10 August 2021

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TUPAB060

Machine Learning on Beam Lifetime and Top-Up Efficiency

network, operation, storage-ring, photon

1499

Y.P. Sun
ANL, Lemont, Illinois, USA

Funding: The work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Both unsupervised and supervised machine learning techniques are employed for automatic clustering, modeling and prediction of Advanced Photon Source (APS) storage ring beam lifetime and top-up efficiency archived in operations. The naive Bayes classifier algorithm is developed and combined with k-means clustering to improve accuracy, where the unsupervised clustering of APS beam lifetime and top-up efficiency is consistent with either true label from data archive or Gaussian kernel density estimation. Artificial neural network algorithms have been developed, and employed for training and modelling the arbitrary relations of beam lifetime and top-up efficiency on many observable parameters. The predictions from artificial neural network reasonably agree with the APS operation data.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB060

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paper received ※ 22 May 2021 paper accepted ※ 21 June 2021 issue date ※ 22 August 2021

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TUPAB085

Three-Dimensional Radiative Effects in the Compression of Ultra-Short Electron Micro-Bunches

FEL, electron, laser, simulation

1577

R. Robles, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

Funding: DOE Contract DE-SC0009914 DOE Contract DE-SC0020409 National Science Foundation Grant No. PHY-1549132
Micro-bunched current profiles have recently gained traction as an alternative to bulk compression in certain free-electron laser applications. The attraction of the micro-bunched structure is owed in part to its promise to minimize deleterious effects associated with coherent synchrotron radiation during compression. Simultaneously, these profiles push the boundaries of traditional one-dimensional CSR simulation models which assume the bunch length to far exceed the transverse beam size in the bunch rest frame - an assumption which may be violated by the sub-micron length micro-bunches. Here we present simulation studies of the impact of three-dimensional CSR effects on micro-bunching based compression schemes using the General Particle Tracer code.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB085

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paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 13 August 2021

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TUPAB094

Multi-Start Foil Wound Solenoids for Multipole Suppression

solenoid, multipole, simulation, quadrupole

1596

N. Majernik, A. Fukasawa, J.B. Rosenzweig, A. Suraj
UCLA, Los Angeles, California, USA

Funding: National Science Foundation Grant No. PHY-1549132 - CBB, DE-SC0020409
Solenoids for beam transport are typically wound helically, with each layer of wire being laid down on top of the previous, or as "pancakes" where the wire is wound radially in before crossing over and winding out. Both of these approaches break rotational symmetry and introduce higher-order multipole moments which can be deleterious to beam emittance. For high brightness beams, this can be particularly problematic. To this end, a solenoid employing multi-start foil windings is simulated and compared to conventional choices. With appropriate design, this approach can forbid certain multipoles by symmetry.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB094

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paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 15 August 2021

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TUPAB095

Arbitrary Longitudinal Pulse Shaping with a Multi-Leaf Collimator and Emittance Exchange

wakefield, acceleration, plasma, laser

1600

N. Majernik, G. Andonian, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
D.S. Doran, G. Ha, J.G. Power, E.E. Wisniewski
ANL, Lemont, Illinois, USA
R.J. Roussel
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA

Funding: DOE HEP Grant DE-SC0017648, and National Science Foundation Grant No. PHY-1549132
Drive and witness beams with variable current profiles and bunch spacing can be generated using an emittance exchange beamline (EEX) in conjunction with transverse masks. Recently, this approach was used to create advanced driver profiles and demonstrate record-breaking plasma wakefield transformer ratios [Roussel, R., et al., Phys. Rev. Lett. 124, 044802 (2020)], a crucial advancement for effective witness acceleration. Presently, these transverse masks are individually laser cut, making the refinement of beam profiles a slow process. Instead, we have proposed the used of a UHV compatible multileaf collimator (MLC) to replace these masks. An MLC permits real-time adjustment of the beam masking, permitting faster optimization in a manner highly synergistic with machine learning. Beam dynamics simulations have shown that practical MLCs offer resolution that is functionally equivalent to that offered by the laser cut masks. In this work, the engineering considerations and practical implementation of such a system at the AWA facility are discussed and the results of benchtop tests are presented.
* Roussel, Ryan, et al. PRL 124.4 (2020): 044802

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB095

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paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 29 August 2021

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TUPAB136

On Nonlinear Electron Beam Dynamics in a Plasma Environment

plasma, electron, linear-dynamics, wakefield

1707

H.Y. Barminova
MEPhI, Moscow, Russia
B. Kak
RUDN University, Moscow, Russia

The nonlinear dynamics of an electron beam propagating in a low-density plasma is investigated. The beam envelope equation is obtained analytically for the case of an axisymmetric beam using a model approximation close to the Kapchinsky-Vladimirsky model. Solutions of the envelope equation are presented for various initial conditions (beam current, initial beam radius, transverse beam emittance).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB136

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paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021

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TUPAB138

Determination of the Phase of Wakefield Driven by a Self-Modulated Proton Bunch in Plasma

plasma, wakefield, electron, proton

1710

K. Moon, M. Chung
UNIST, Ulsan, Republic of Korea
P. Muggli
MPI-P, München, Germany

Funding: This work was partly supported by the National Research Foundation of Korea (Nos. NRF-2016R1A5A1013277 and NRF-2020R1A2C1010835)
The phase of wakefield driven by a self-modulated proton bunch depends on the type of seeding method and by the beam-plasma parameters.* Particularly when a preceding electron bunch generates seed wakefield, the proton bunch modulation is strongly affected by the seed bunch dynamics along with the plasma. Intrinsic wakefield dephasing from self-modulation of proton bunch can lead to complex evolution of the bunch and wakefield, making it difficult to design an experimental setup for witness beam injection. Using the particle-in-cell code FBPIC,** we investigate in detail the trends of seed electron and driver proton bunch parameter sensitivity to the phase of wakefield in time in the proton bunch frame. We focus on the parameters affecting the phase of the wakefield through the beam’s radial dynamics, such as beam emittance, radial size, energy, and beam to plasma density ratio. Parameter variations are compared to those in the case of the phase of wakefield driven by a non-evolving seed bunch.
*F. Batsch, arXiv:2012.09676 [physics.plasm-ph]
**R. Lehe, M. Kirchen, I.A. Andriyash, B.B. Godfrey, and J.-L. Vay, Comput. Phys. Comm. 203, 66-82 (2016)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB138

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021

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TUPAB147

Asymmetric Beam Driven Plasma Wakefields at the AWA

plasma, wakefield, simulation, electron

1732

P. Manwani, H.S. Ancelin, G. Andonian, J.B. Rosenzweig, M. Yadav
UCLA, Los Angeles, California, USA
G. Andonian
RadiaBeam, Santa Monica, California, USA
G. Ha, J.G. Power
ANL, Lemont, Illinois, USA
M. Yadav
The University of Liverpool, Liverpool, United Kingdom
M. Yadav
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was performed with the support of the US Department of Energy, Division of High Energy Physics under Contract No. DE-SC0017648 and DE-SC0009914
In future plasma wakefield acceleration-based scenarios for linear colliders, beams with highly asymmetric emittance are expected. In this case, the blowout region is no longer axisymmetric, but elliptical in cross-section, which implies that the focusing is not equal in the two transverse planes. In this paper, we analyze simulations for studying the asymmetries in flat-beam driven plasma acceleration using the round-to-flat-beam transformer at the Argonne Wakefield Accelerator. Beams with high charge and emittance ratios, in excess of 100:1, are routinely available at the AWA. We use particle-in-cell codes to compare various scenarios including a weak blowout, where the plasma focusing effect exhibits higher order mode asymmetry. Further, practical considerations for tunable plasma density using capillary discharge and laser ionization are compared for implementation into experimental designs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB147

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paper received ※ 20 May 2021 paper accepted ※ 13 July 2021 issue date ※ 02 September 2021

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TUPAB158

Electron Witness Constraints for AWAKE

plasma, acceleration, wakefield, electron

1753

J.P. Farmer, P. Muggli
MPI-P, München, Germany
E. Gschwendtner
CERN, Meyrin, Switzerland
L. Liang
The University of Manchester, Manchester, United Kingdom
M.S. Weidl
MPI/IPP, Garching, Germany

The AWAKE project at CERN successfully demonstrated the use of a proton driver to accelerate an electron witness in plasma*. One of the key goals for AWAKE Run2 is to better control this acceleration, separating the proton-beam-modulation and electron-acceleration stages in order to achieve high energy electrons with high beam quality. Controlled acceleration additionally requires careful tuning of the witness bunch parameters at the injection point. In this work, we use particle-in-cell simulations to study the tolerances for this matching, and discuss techniques to loosen these constraints.
*Adli et al. (AWAKE Collaboration), Nature (2018)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB158

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paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 11 August 2021

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TUPAB168

Beam Commissioning of a 325 MHz Proton IH-DTL at XiPAF

DTL, cavity, proton, linac

1777

P.F. Ma, X. Guan, R. Tang, M.W. Wang, X.W. Wang, Q.Z. Xing, W.B. Ye, S.X. Zheng
TUB, Beijing, People’s Republic of China
W. Chen, W.L. Liu, W. Lv, M.T. Qiu, B.C. Wang, D. Wang, M.C. Wang, Z.M. Wang, Y.H. Yan, Y. Yang, M.T. Zhao
NINT, Xi’an, People’s Republic of China

The Inter-Digital H-mode Drift Tube Linac (IH-DTL) is widely used as the main component of injectors for medical synchrotrons. This paper describes the beam commissioning of a compact 325 MHz IH-DTL with modified KONUS beam dynamics at Tsinghua University (THU). This IH-DTL accelerates the proton beam from 3 MeV to 7 MeV in 1m. The average energy of the beam is 7.0 MeV with the energy spread range of -0.6 MeV to 0.3 MeV. The output transverse normalized RMS emittance of the beam is 0.58 (x)/0.58 (y) pi mm mrad with the input emittance of 0.43 (x)/0.37 (y) pi mm mrad. The beam test results show good agreement with the beam dynamics design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB168

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paper received ※ 08 May 2021 paper accepted ※ 16 June 2021 issue date ※ 14 August 2021

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TUPAB170

Decouple Transverse Coupled Beam in the DTL with Tilted PMQs

coupling, DTL, rfq, cavity

1785

P.F. Ma, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng
TUB, Beijing, People’s Republic of China
Y.H. Pu, J. Qiao, C.P. Wang, X.C. Xie, F. Yang
Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China

The coupling of the beam is widely studied in the accelerator physics field. Projected transverse emittances easily grow up if the beam is transversely-coupled. If we decouple the transverse coupled beam, the transverse emittance can be small. The matrix approach based on the symplectic transformation theory for decoupling the coupled beam is summarized. For a proton accelerator, the transverse coupled beam is introduced by an RFQ tilted by 45°. The beam is decoupled with the first five tilted quadrupoles mounted in the DTL section. A study on the gradient choice of the quadrupoles and the space charge effect is given in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB170

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paper received ※ 08 May 2021 paper accepted ※ 21 June 2021 issue date ※ 28 August 2021

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TUPAB171

Linear Transfer Matrix of a Half Solenoid

solenoid, optics, coupling, ion-source

1789

P.F. Ma, X. Guan, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng
TUB, Beijing, People’s Republic of China

Solenoid magnets can provide strong transverse focusing to electrons and ions with relatively small energies. For the ECR heavy-ion source, the ions are extracted at the central area of the solenoid, the beam is coupled at the exit of the source. The coupling caused by the solenoids can lead to the growth of projected transverse emittance, which has been widely studied with great interest. It is important to study the transfer matrix of a half solenoid to study the beam optics in an ECR souce, thus the property of the beam can be given. Based on the transfer matrix calculation, the summary of the linear transfer matrix of a half solenoid can be given. The beam optics in a half solenoid is studied.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB171

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paper received ※ 18 May 2021 paper accepted ※ 28 June 2021 issue date ※ 29 August 2021

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TUPAB173

ESS Drift Tube Linac Manufacturing, Assembly and Tuning

DTL, linac, cavity, alignment

1797

F. Grespan, L. Antoniazzi, A. Baldo, C. Baltador, A. Battistello, L. Bellan, P. Bottin, M. Comunian, D. Conventi, E. Fagotti, L. Ferrari, A. Palmieri, R. Panizzolo, A. Pisent, D. Scarpa
INFN/LNL, Legnaro (PD), Italy
R.A. Baron
ESS, Lund, Sweden
T. Bencivenga, P. Mereu, C. Mingioni, M. Nenni, E. Nicoletti
INFN-Torino, Torino, Italy
A.G. Colombo
INFN- Sez. di Padova, Padova, Italy
B. Jones
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The Drift Tube Linac (DTL) for the ESS Linac will accelerate H⁺-beams of up to 62.5 mA peak current from 3.62 to 90 MeV. The structure consists of five cavities. The first cavity (DTL1) is a 7.6 m long tank containing 60 drift tubes, 23 fixed tuners, 3 movable tuners and 24 post-couplers, operating at a frequency of 352.21 MHz and an average accelerating field of 3.0 MV/m. The cavity is now assembled at ESS, the results of alignment and tuning are here presented. The DTL1 "as-built" as been analyzed from the beam dynamics point of view. The manufacturing of DTL4 and DTL3 is completed and they are now under assembly at ESS. DTL2 and DTL5 manufacturing will be completed within 2021. The paper describes the production and assembly stages, with a focus on the statistics of quality check in terms of metrology, alignment, leak tests.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB173

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paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 14 August 2021

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TUPAB181

Demonstration of Electron Cooling using a Pulsed Beam from an Electrostatic Electron Cooler

electron, experiment, space-charge, timing

1827

M.W. Bruker, S.V. Benson, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, T. Satogata, A.V. Sy, H. Wang, S. Wang, H. Zhang, Y. Zhang
JLab, Newport News, Virginia, USA
J. Li, F. Ma, X.M. Ma, L.J. Mao, X.P. Sha, M.T. Tang, J.C. Yang, X.D. Yang, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China
H. Zhao
BNL, Upton, New York, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Electron cooling continues to be an invaluable technique to reduce and maintain the emittance in hadron storage rings in cases where stochastic cooling is inefficient and radiative cooling is negligible. Extending the energy range of electron coolers beyond what is feasible with the conventional, electrostatic approach necessitates the use of RF fields for acceleration and, thus, a bunched electron beam. To experimentally investigate how the relative time structure of the two beams affects the cooling properties, we have set up a pulsed-beam cooling device by adding a synchronized pulsing circuit to the conventional electron source of the CSRm cooler at Institute of Modern Physics *. We show the effect of the electron bunch length and longitudinal ion focusing strength on the temporal evolution of the longitudinal and transverse ion beam profile and demonstrate the detrimental effect of timing jitter as predicted by theory and simulations. Compared to actual RF-based coolers, the simplicity and flexibility of our setup will facilitate further investigations of specific aspects of bunched cooling such as synchro-betatron coupling and phase dithering.
* M. W. Bruker et al., Phys. Rev. Accel. Beams 24, 012801 (2021)

Poster TUPAB181 [3.699 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB181

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paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 21 August 2021

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TUPAB192

Studies on Momentum Collimation for CSNS-RCS Upgrades

collimation, bunching, betatron, space-charge

1855

Y.W. An, J. Chen, S.Y. Xu, Y. Yuan
IHEP, Beijing, People’s Republic of China
X.H. Lu, J.B. Yu
IHEP CSNS, Guangdong Province, People’s Republic of China

The CSNS project was a high intensity pulsed facility, and achieved the the design goal of 100kW in 2020. The upgrades of the CSNS are proposed, and the momentum collimator is a component of the upgrades. This paper will show the design scheme of the momentum collimator and the simulation results are also presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB192

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paper received ※ 18 May 2021 paper accepted ※ 15 June 2021 issue date ※ 28 August 2021

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TUPAB206

Matching of Intense Beam in Six-Dimensional Phase Space

space-charge, focusing, framework, quadrupole

1897

Y.K. Batygin
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by US DOE under contract 89233218CNA000001
Beam matching is a common technique that is routinely employed in accelerator design to minimize beam losses. Despite being widely used, a full theoretical understanding of beam matching in 6D phase space remains elusive. Here, we present an analytical treatment of 6D beam matching of a high-intensity beam onto an RF structure. We begin our analysis within the framework of a linear model, and apply the averaging method to attain a matched solution for a set of 3D beam envelope equations. We then consider the nonlinear regime, where the beam size is comparable with the separatrix size. Starting with a Hamiltonian analysis in 6D phase space, we attain a self-consistent beam profile and show that it is significantly different from the commonly used ellipsoidal shape. Subsequently, we analyze the special case of equilibrium with equal space charge depression between all degrees of freedom. A comparison of beam dynamics for equipartitioned, equal space charge depression, and equal emittances beams is given.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB206

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paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 24 August 2021

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TUPAB219

Equilibrium and Nonlinear Beam Dynamics Parameters From Sirius Turn-by-Turn BPM Data

experiment, betatron, optics, factory

1935

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

A considerable amount of beam information is conveyed by Turn-by-Turn (TbT) data of Beam Position Monitors (BPM). In this work such data sets are analyzed for Sirius, the Brazilian 4th Generation 3GeV synchrotron light source. In particular, equilibrium and non-linear beam dynamics parameters determining decoherence patterns in TbT position data are estimated and compared with corresponding values of the nominal storage ring model.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB219

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paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 15 August 2021

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TUPAB227

Simultaneous Compensation of Phase and Amplitude Dependent Geometrical Resonances Using Octupoles

octupole, sextupole, lattice, resonance

1960

F. Plassard, Y. Hidaka, Y. Li, T.V. Shaftan, V.V. Smaluk, G.M. Wang
BNL, Upton, New York, USA

As the new generation of light sources are pushing toward diffraction limited storage rings with ultra-low emittance beams, nonlinear beam dynamics become increasingly difficult to control. It is a common practice for modern designs to use a sextupole scheme that allows simultaneous correction of natural chromaticity and energy independent, or geometrical, sextupolar resonances. However, the remaining higher order terms arising from the cross talks of the sextupole families set a strong limitation on the achievable dynamic aperture. This paper presents a simulation-based recipe to use octupoles together with this sextupole scheme to provide simultaneous self-compensation of linear amplitude dependent tune shift together with phase-dependent octupolar and higher order geometrical resonant driving terms. The correction method was built based on observations made on a simple FODO model, then applied to a realistic low emittance lattice, designed in the framework of the upgrade of the National Synchrotron Light Source II (NSLS-II).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB227

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paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 14 August 2021

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TUPAB231

Cooling of an Annular Beam by Using Nonlinear Effects

resonance, dipole, extraction, proton

1968

F. Capoani, M. Giovannozzi, R. Tomás García
CERN, Geneva, Switzerland
A. Bazzani, F. Capoani
Bologna University, Bologna, Italy

In recent years, nonlinear effects have been used to modify the transverse beam distribution by crossing nonlinear resonances adiabatically. This allows generating transversally split beams, in which the initial single Gaussian is divided into several ones depending on the order and stability type of the resonance used. Nonlinear effects could be used to try and cool a beam by acting on its transverse beam distribution. In this paper, we present and discuss the special case of a beam with an annular distribution, showing how the resulting emittance could be reduced by means of nonlinear effects.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB231

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paper received ※ 10 May 2021 paper accepted ※ 16 June 2021 issue date ※ 21 August 2021

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TUPAB232

Linear Coupling and Adiabaticity of Emittance Exchange

resonance, coupling, extraction, proton

1972

F. Capoani, M. Giovannozzi
CERN, Geneva, Switzerland
A. Bazzani, F. Capoani
Bologna University, Bologna, Italy
A.I. Neishtadt
IKI, Moscow, Russia
A.I. Neishtadt
Loughborough University, Leicestershre, United Kingdom

In circular accelerators, crossing the coupling resonance induces the exchange of the transverse emittances, provided the process is adiabatic. In this paper, we introduce a theoretical framework to analyze the resonance-crossing process, based on Hamiltonian mechanics, which is capable of explaining all the features of the emittance exchange process.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB232

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paper received ※ 11 May 2021 paper accepted ※ 16 June 2021 issue date ※ 27 August 2021

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TUPAB241

Characterization of the RF-Cavities geometry in Order to Optimize the Beam Parameters in S-Band On-Axis LINACs

cavity, electron, target, impedance

2005

A. Khosravi, B. Shokri
LAPRI, Tehran, Iran
N. Khosravi
ILSF, Tehran, Iran

The RF characteristics of an accelerating tube are primarily assigned to geometrical features of a cavity. As a consequence of this geometry, the final electric field will make the shape of our Gaussian bunch and the final dose. The accelerating field can be studied considering the nose cone, gap, and bore radius. In dual electron linacs, the role of input power and bunch current is inevitable. Therefore, the geometrical issues of RF-cavities are studied in a 6MeV electron on-axis SW tube. To make an accurate comparison, each RF-cavity is designed and optimized by POISSON SU-PERFISH. The optimized cavities are imported to the PIC solver of CST. Then the beam characteristics are studied on a predefined target.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB241

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paper received ※ 18 May 2021 paper accepted ※ 14 June 2021 issue date ※ 30 August 2021

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TUPAB242

The Beam-Study of the Side and On-Axis RF Cavities in S-Band 6 MeV LINACs

cavity, target, coupling, impedance

2008

A. Khosravi, B. Shokri
LAPRI, Tehran, Iran
N. Khosravi
ILSF, Tehran, Iran

The geometry of side and on-axis RF cavities are two magnetic-coupled designs for the different LINAC applications. The electromagnetic fields, RF power, beam parameters, thermal stability, and manufacturing costs are the most critical factors in cavity type selection in each application. In this article, both RF-cavities are optimized in POISSON SUPERFISH code to compare the beam parameters accurately. Then the optimized cavities are making a tube and compare in ASTRA 1D code and CST 3D software. At last, the thermal sensitivity of both models is studied in MPHYSICS module of the CST. As a result, the final decision can be achieved on the side or on-axis cavities considering the input power, costs, beam properties, and thermal stability for the different applications of the LINACs

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB242

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paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021

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TUPAB243

Investigation of the Buncher Effect on Beam Properties in SW 3-6 MeV LINACs

cavity, electron, target, impedance

2012

A. Khosravi, B. Shokri
LAPRI, Tehran, Iran
N. Khosravi
ILSF, Tehran, Iran

The best quality of an electron beam is the primary goal of a linear accelerator design. Beam-study on a buncher section can lead us to a better perspective of the modulation and acceleration of a beam to optimize the final Gaussian beam. Five setups of different bunchers are designed, optimized, and presented in this article. A more brilliant and converged beam with a higher current, transverse emittance and smaller beam size is the study’s goal.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB243

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paper received ※ 18 May 2021 paper accepted ※ 14 June 2021 issue date ※ 26 August 2021

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TUPAB254

Limiting Coherent Longitudinal Beam Oscillations in the EIC Electron Storage Ring

feedback, electron, cavity, hadron

2046

B. Podobedov
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
M. Blaskiewicz
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.
We study coherent longitudinal beam oscillations in the EIC electron storage ring (ESR). We show that to avoid unacceptable hadron emittance growth due to finite crossing angle, the amplitude of these oscillations needs to be limited to a fraction of a millimeter. Using an analytical model we estimate the amplitude of these oscillations under the two scenarios: 1) the beam is passively stable and the oscillations are driven by RF phase noise only; 2) a coupled-bunch instability, presently expected in the ESR, is damped by a longitudinal feedback system. We show that, for the 2nd scenario, comfortable specifications for RF phase noise and feedback sensor noise will be sufficient to maintain the oscillation amplitude within the required limits.

Poster TUPAB254 [1.347 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB254

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paper received ※ 12 May 2021 paper accepted ※ 18 June 2021 issue date ※ 26 August 2021

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TUPAB256

Investigation of Damping Effects of the Crab Cavity Noise Induced Emittance Growth

simulation, impedance, cavity, experiment

2054

N. Triantafyllou, L.R. Carver, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
F. Antoniou, H. Bartosik, P. Baudrenghien, X. Buffat, R. Calaga, Y. Papaphilippou, N. Triantafyllou
CERN, Meyrin, Switzerland
L.R. Carver
ESRF, Grenoble, France
T. Mastoridis
CalPoly, San Luis Obispo, California, USA

Crab cavities will be installed at the two main interaction points (IP1 and IP5) of the High Luminosity LHC (HL-LHC) in order to minimize the geometric reduction of the luminosity due to the crossing angle. Two prototype crab cavities have been installed into the SPS machine and were tested with a proton beam in 2018, to study the expected emittance growth induced by RF noise. The measured emittance growth was found to be a factor 2-3 lower than predicted from the available analytical and computational models. Damping mechanisms from the transverse impedance, which is not included in the available theories, are studied as a possible explanation for the observed discrepancy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB256

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paper received ※ 18 May 2021 paper accepted ※ 18 June 2021 issue date ※ 23 August 2021

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TUPAB265

Bunch Lengthening of the HALF Storage Ring in the Presence of Passive Harmonic Cavities

cavity, storage-ring, simulation, damping

2082

T.L. He, Z.H. Bai, G.Y. Feng, W. Li, W.W. Li, G. Liu, L. Wang, H. Xu, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

A passive 3^rd harmonic RF system, being necessary for the Hefei Advanced Light Facility (HALF) storage ring under design, will be employed to lengthen the bunches for suppressing the intrabeam scattering and improving the beam lifetime. However, the transient beam loading due to the fundamental mode may significantly reduce the bunch lengthening. Since the scale of transient effects is proportional to R/Q, the effects of R/Q on bunch lengthening, in uniform fill pattern with the near-optimum condition fulfilled, are analyzed by multibunches multiparticles tracking simulation. It indicates that the passive superconducting harmonic cavity with a lower R/Q is preferred by HALF.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB265

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paper received ※ 16 May 2021 paper accepted ※ 18 June 2021 issue date ※ 20 August 2021

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TUPAB362

Physical Design of Electrostatic Deflector in CSNS Muon Source

simulation, positron, high-voltage, operation

2360

Y.W. Wu, S. Li, J.Y. Tang, X. Wu
IHEP, Beijing, People’s Republic of China
C.D. Deng, Y. Hong
DNSC, Dongguan, People’s Republic of China
Y.Q. Liu
IHEP CSNS, Guangdong Province, People’s Republic of China

CSNS will build a muon source at the end of the RTBT. In the current design, the muon source propose two schemes, namely the baseline scheme and the baby scheme. High voltage electrostatic deflectors (ESD) are used to deflect the beam in the two schemes. A three-channel ESD with 400 kV HV is employed in the baseline scheme and a 210 kV dual-channel ESD in the simplified scheme. According to physical requirements, the electric field concentration factor is introduced, and the electrode of ESD is theoretically designed. 2D and 3D simulations are carried out to analyze the characteristics of electric field distribution by OPERA. The geometry of the electrodes also met the requirements of electric field uniformity, high voltage resistance and mechanical strength at the same time. In the baseline scheme and the baby scheme, the ESD electric field concentration factors are 1.36 and 1.53, and the maximum electric field is 6.78MV/m and 4.6MV/m, respectively. The design meets the requirements and is reasonably feasible.

Poster TUPAB362 [2.214 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB362

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paper received ※ 13 May 2021 paper accepted ※ 09 June 2021 issue date ※ 22 August 2021

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TUPAB363

Feasibility Study for the Novel CERN PS Fast Extraction Septum

septum, extraction, simulation, HOM

2363

T. Helseth, M.G. Atanasov, B. Balhan, J.C.C.M. Borburgh, L. Ducimetière, M.A. Fraser, T. Kramer
CERN, Geneva, Switzerland

In the framework of accelerator consolidation, a feasibility study for a novel CERN PS extraction septum has been conducted. Functional requirements have been established and, accordingly, a system of two septa magnets and their associated pulse generator is proposed. The magnetic septum design is based on eddy current topology. Magnetic simulations in Flux 2D and Opera 3D of a conceptual design have been carried out. The short length and high amplitude of the current pulse required to drive the eddy current septa imply that none of the power converters currently used for septa magnets at CERN will be suitable. Pulse generator topologies derived from kicker generators have therefore been explored and simulated in Spice. The conceptual magnet and generator design along with simulation results are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB363

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paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 10 August 2021

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TUPAB368

Design of the Longitudinal Gradient Dipole Magnets for HALF

dipole, permanent-magnet, storage-ring, lattice

2378

M.Y. Mingyao
Wang, Hefei, People’s Republic of China
G.Y. Feng, Z.L. Ren, H. Xu
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Hefei Advanced Light Facility (HALF) is the fourth generation diffraction-limited storage ring light source project in China. The lattice of the storage ring consists of six different dipoles with longitudinal gradients. The longitudinal-gradient dipoles (LGBs) are permanent magnets. This paper presents the designed construction of LGBs and the magnetic field results using OPERA3D. By optimizing the shape of the polar surface, the magnetic field uniformity is optimized to about 5×10^-4. With some movable adjusting block, the magnetic field can be controlled accurately. The temperature stability of the magnet is better than 0.0074 T*mm/°C by setting temperature compensating shunt.

Poster TUPAB368 [0.862 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB368

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paper received ※ 15 May 2021 paper accepted ※ 02 June 2021 issue date ※ 10 August 2021

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TUPAB387

Superconducting Solenoid Field Measurement and Optimization

solenoid, quadrupole, multipole, gun

2425

S. Ma, A. Arnold, P. Murcek, A.A. Ryzhov, J. Schaber, J. Teichert, R. Xiang, P.Z. Zwartek
HZDR, Dresden, Germany
H.J. Qian
DESY Zeuthen, Zeuthen, Germany

The solenoid is a significant part of an electron injector to provide a proper focusing, and preserve the beam projected emittance. A superconducting solenoid is applied for the SRF photoinjector at HZDR. The solenoid itself can degrade electron beam quality due to magnetic field imperfections like multipole components. In order to determine the field aberrations in the solenoid, we measured the superconducting solenoid magnetic field in the cryomodule. A simple and effective method is used to analyze the multipole field components, which will be presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB387

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 20 August 2021

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TUPAB407

A Novel Beam Optics Concept to Maximize the Transmission Through Cyclotron-based Proton Therapy Gantries

optics, proton, quadrupole, simulation

2477

V. Maradia, A.C. Giovannelli, A.L. Lomax, D. Meer, S. Psoroulas, J.M. Schippers, D.C. Weber
PSI, Villigen PSI, Switzerland
V. Maradia
ETH, Zurich, Switzerland
D.C. Weber
University of Zurich, University Hospital, Zurich, Switzerland
D.C. Weber
KRO, Bern, Switzerland

Funding: This work is funded by a PSI inter-departmental funding initiative (CROSS).
Most of the conventional beam optics of cyclotron-based proton gantries were designed to provide point-to-point focus in both planes with an imaging factor between 1 and 2 from the entrance of the gantry to the patient. This means that a small beam size at the gantry entrance is required to achieve the required small beam size at the patient. Due to the typically used beam emittance, this in turn results in large beam divergence at the gantry entrance, increasing the possibility of beam losses along the gantry as the beam envelope gets close to the apertures. To maximize transmission through the gantry, we propose a novel beam optics concept using 3:1 imaging. It reduces the beam divergence at the gantry entrance by factor 3 while still achieving a small beam size at the patient. The beam envelope is better controlled and keeps clear of the apertures compared to the 1:1 or 1:2 imaging beam envelope. For PSI Gantry 2, the novel 3:1 imaging beam optics increase the proton beam transmission for lower energies by 40% compare to 1:1 imaging beam optics. The usage of small imaging factors can help to maximize transmission for different gantry lattices, thus reducing treatment times.

Poster TUPAB407 [1.347 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB407

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paper received ※ 10 May 2021 paper accepted ※ 02 June 2021 issue date ※ 29 August 2021

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WEXA01

Successful Crabbing of Proton Beams

cavity, luminosity, collider, impedance

2510

R. Calaga
CERN, Meyrin, Switzerland

Funding: Research supported by the HL-LHC project and by the DOE and UK-STFC.
Many future particle colliders require beam crabbing to recover the geometric luminosity loss from the non-zero crossing angle at the interaction point. A first demonstration experiment of crabbing with hadron beams was successfully carried out with high energy protons. This breakthrough result is fundamental to achieve the physics goals of the high luminosity LHC upgrade project (HL-LHC) and the future circular collider (FCC). The expected peak luminosity gain (related to collision rate) is 65% for HL-LHC, and even greater for the FCC. Novel beam physics experiments with proton beams in CERN’s Super Proton Synchrotron (SPS) were performed to demonstrate several critical aspects for the operation of crab cavities in the future HL-LHC including transparency with a pair of cavities, a full characterization of the cavity impedance with high beam currents and controlled emittance growth from crab cavity induced RF noise.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA01

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paper received ※ 14 May 2021 paper accepted ※ 28 July 2021 issue date ※ 24 August 2021

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WEXA04

The RCS Design Status for the Electron Ion Collider

resonance, electron, injection, lattice

2521

V.H. Ranjbar, M. Blaskiewicz, Z.A. Conway, D.M. Gassner, C. Hetzel, B. Lepore, H. Lovelace III, I. Marneris, F. Méot, C. Montag, J. Skaritka, N. Tsoupas, E. Wang, F.J. Willeke
BNL, Upton, New York, USA
J.M. Grames, J. Guo, F. Lin, V.S. Morozov, T. Satogata
JLab, Newport News, Virginia, USA
D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The design of the Electron-Ion Collider Rapid Cycling Synchrotron (RCS) to be constructed at Brookhaven National Laboratory is advancing to meet the injection requirements for the Electron Storage Ring (ESR). Over the past year activities are focused on developing the approach to inject two 28 nC bunches every second, up from the original design of one 10nC bunch every second. The solution requires several key changes concerning the injection and extraction kickers, charge accumulation via bunch merging and a carefully calibrated RF acceleration profile to match the longitudinal emittance required by the ESR.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA04

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paper received ※ 19 May 2021 paper accepted ※ 31 August 2021 issue date ※ 10 August 2021

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WEXB07

Transverse Beam Profile Measurements from Extraction Losses in the PS

extraction, septum, kicker, proton

2548

J.R. Hunt, F. Cerutti, L.S. Esposito, M. Giovannozzi, A. Huschauer, G. Russo
CERN, Geneva, Switzerland
G. Russo
Goethe Universität Frankfurt, Frankfurt am Main, Germany

During Multi-Turn Extraction (MTE) of continuous beams in the Proton Synchrotron (PS) at CERN, losses are generated on the blade of both the active and non-active septum during the rise time of the extraction kickers. Utilising pCVD Diamond detectors, secondary signal generated from these losses is measured. The high time resolution of these devices allows for insight into the detail of the horizontal beam distribution during extraction, and hence useful information such as the horizontal beam emittance may be computed. In this contribution, FLUKA simulations to relate the detector response to the beam impact conditions on the blades of the two septa are presented. The dependence on the beam angle, magnetic fringe field, and positioning of the detector is explored. Finally, realistic beam distributions are used to determine expected signal profiles at each septum.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB07

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paper received ※ 18 May 2021 paper accepted ※ 20 July 2021 issue date ※ 27 August 2021

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WEXB08

Beam Losses and Emittance Growth Studies at the Record High Space-Charge in the Booster

booster, space-charge, proton, operation

2552

V.D. Shiltsev, J.S. Eldred, V.A. Lebedev, K. Seiya
Fermilab, Batavia, Illinois, USA

Comprehensive studies of high intensity proton beams in the 0.4-8 GeV FNAL Booster synchrotron have revealed interesting nonlinear dynamics of the beam losses and emittance growth at the record high dQ_SC=0.6. We report the results of the studies and directions of further improvements to prepare the Booster to the era of even higher intensity operation with new 0.8 GeV PIP-II linac.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB08

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paper received ※ 24 May 2021 paper accepted ※ 02 July 2021 issue date ※ 17 August 2021

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WEPAB001

Accelerator Challenges of the LHeC Project

electron, optics, linac, proton

2570

B.J. Holzer, K.D.J. André, O.S. Brüning
CERN, Geneva, Switzerland
S.A. Bogacz
JLab, Newport News, Virginia, USA
M. Klein
The University of Liverpool, Liverpool, United Kingdom

The LHeC project studies the design of a future electron-proton collider at CERN that will run in parallel to the standard LHC operation. For this purpose, the existing LHC storage ring will be combined with an Energy Recovery Linac (ERL), to accelerate electrons up to kinetic energy of 50 GeV. This concept - also applicable to the FCC-eh collider and studied at the PERLE project as prototype version - allows a peak luminosity of 10³⁴ cm^-2 s^-1. A sophisticated design of the RF structures, linacs, arcs, and interaction region is required. The electrons are accelerated and, after the interaction point, their energy is recovered through the same RF structures. While this energy recovery concept is a very promising approach, severe challenges are set by the layout of the interaction region, the beam separation concept and the design of the linac and arc lattice for the highest possible momentum acceptance. Emittance control and beam-beam effect of both, electron and proton beams, have been studied in front-to-end simulations and will be presented. We summarise the design principles of the ERL, the optimization of the arc lattice, and the main parameters of the project.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB001

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paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 21 August 2021

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WEPAB004

Electron-Ion Luminosity Maximization in the EIC

luminosity, electron, collider, hadron

2582

W. Fischer, E.C. Aschenauer, M. Blaskiewicz, K.A. Drees, A.V. Fedotov, H. Huang, C. Montag, V. Ptitsyn, D. Raparia, V. Schoefer, K.S. Smith, P. Thieberger, F.J. Willeke
BNL, Upton, New York, USA
Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The electron-ion luminosity in EIC has a number of limits, including the ion intensity available from the injectors, the total ion beam current, the electron bunch intensity, the total electron current, the synchrotron radiation power, the beam-beam effect, the achievable beta functions at the interaction points (IPs), the maximum angular spreads at the IP, the ion emittances reachable with stochastic or strong cooling, the ratio of horizontal to vertical emittance, and space charge effects. We map the e-A luminosity over the center-of-mass energy range for some ions ranging from deuterons to uranium ions. For e-Au collisions the present design provides for electron-nucleon (e-Au) peak luminosities of 1.7x1033 cm^-2s⁻¹ with stochastic cooling, and 4.7x1033 cm^-2s⁻¹ with strong hadron cooling.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB004

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paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 20 August 2021

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WEPAB008

Numerical Noise Study in EIC Beam-Beam Simulations

simulation, electron, proton, resonance

2592

D. Xu, Y. Hao
FRIB, East Lansing, Michigan, USA
Y. Luo, C. Montag
BNL, Upton, New York, USA
J. Qiang
LBNL, Berkeley, California, USA

In the Electron-Ion Collider (EIC) design, a flat beam collision scheme is adopted to achieve 1e34 luminosity. We found that the vertical growth of the proton beam is much larger than of the round beam. In this article we present the numerical noise study about the number of macroparticles, the electron slice number, and the electron bunch length. Both weak-strong and strong-strong simulation methods are used. It turns out the proton emittance growth in the strong-strong simulation mainly comes from the numberical noise. This study helps us to perform beam-beam simulation correctly for EIC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB008

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paper received ※ 17 May 2021 paper accepted ※ 31 August 2021 issue date ※ 31 August 2021

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WEPAB011

Update on the Low Emittance Tuning of the e⁺/e^- Future Circular Collider

alignment, sextupole, quadrupole, lattice

2601

T.K. Charles
The University of Liverpool, Liverpool, United Kingdom
B.J. Holzer, F. Zimmermann
CERN, Geneva, Switzerland
K. Oide
KEK, Ibaraki, Japan

The FCC-ee project studies the design of a future 100 km e+/e circular collider for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 10³⁵ cm^-2 s⁻¹. To achieve ultra-low vertical emittance a highly effective emittance tuning scheme is required. In this paper, we describe a comprehensive correction strategy used for the low emittance tuning. The strategy includes Dispersion Free Steering, linear coupling compensation based on Resonant Driving Terms and beta beat correction utilising response matrices.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB011

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paper received ※ 18 May 2021 paper accepted ※ 23 June 2021 issue date ※ 02 September 2021

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WEPAB039

Construction of a Compact Electron Injector Using a Gridded RF Thermionic Gun and a C-Band Accelerator

linac, electron, injection, operation

2687

T. Inagaki, T. Asaka, T. Hara, T. Hiraiwa, N. Hosoda, E. Iwai, C. Kondo, H. Maesaka, T. Ohshima, H. Tanaka
RIKEN SPring-8 Center, Hyogo, Japan
H. Dewa, T. Magome, Y. Minagawa, T. Sakurai
JASRI/SPring-8, Hyogo-ken, Japan
T. Fukui
RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan
S. Hashimoto
LASTI, Hyogo, Japan
S.I. Inoue, K. Kajimoto, S. Nakata, T. Seno, H. Sumitomo, R. Takesako, S. Tanaka, R. Yamamoto, M. Yoshioka
SES, Hyogo-pref., Japan
K. Yanagida
JASRI, Hyogo, Japan

A compact and low-cost 1 GeV injector linac was designed and constructed to provide injection beams to the soft X-ray synchrotron radiation facility NewSUBARU instead of the SPring-8 injector system, which will be shutdown. The total length of the injector linac needs to be less than 70 m to fit into the existing tunnel. To this end, an RF electron gun with a gridded thermionic cathode directly attached to a 238 MHz RF cavity was developed and adopted. The 500 keV, 0.6 ns, 1 nC beam emitted from the cavity is compressed to 3 ps by velocity bunching driven by a 476 MHz RF cavity and a S-band RF structure. The short-pulsed beams are accelerated up to 1 GeV with 16 C-band RF structures. In the C-band accelerator section, the klystron output of 50 MW is multiplied 4 times by a pulse compressor and fed to the 4 RF structures to generate a high accelerating field of 31 MV/m. A low-level RF system consisting of a MTCA.4 based high-speed digitizers and RF frontend boards has been constructed. This injector system is used at the 3 GeV SR facility currently under construction in Sendai. In this paper, we report the design outline and the operational performance of the injector system.

Poster WEPAB039 [2.419 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB039

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paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 24 August 2021

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WEPAB040

Characterization of Low Emittance Electron Beams Generated by Transverse Laser Beam Shaping

laser, flattop, electron, cathode

2690

M. Groß, N. Aftab, P. Boonpornprasert, G.Z. Georgiev, J. Good, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, D. Melkumyan, S.K. Mohanty, R. Niemczyk, A. Oppelt, H.J. Qian, G. Shu, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
Y. Chen, G. Loisch
DESY, Hamburg, Germany
I. Will
MBI, Berlin, Germany

Linac based X-ray free electron laser demand a high beam quality from the electron source, therefore RF photoinjectors are used to generate the electron bunches for state of the art beam brightness. One important figure of merit for these injectors is the transverse emittance of the generated electron beam, which can be minimized by shaping the photocathode laser pulses. Best performance can be achieved with ellipsoidal laser pulses, but 3D shaping is technically challenging. Typically, a quasi-uniform transverse laser profile is truncated from the Gaussian profile generated by the laser with an aperture to reduce the transverse nonlinear space charge forces. This is investigated in detail by optimizing the laser transverse profile at the Photoinjector Test facility at DESY in Zeuthen (PITZ), where photoinjector R&D is conducted for the E-XFEL and FLASH free electron lasers at DESY in Hamburg. In this contribution we present experimental results at high acceleration gradients (up to 60 MV/m) for both 250 pC and 500 pC. For a bunch charge of 500 pC an emittance reduction of about 30% compared to the commonly used transverse flat-top laser distribution was achieved.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB040

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paper received ※ 17 May 2021 paper accepted ※ 02 June 2021 issue date ※ 19 August 2021

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WEPAB051

Beam Dynamics for a High Field C-Band Hybrid Photoinjector

electron, cathode, linac, gun

2714

L. Faillace, F. Bosco, M. Carillo, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
R.B. Agustsson, I.I. Gadjev, S.V. Kutsaev, A.Y. Murokh
RadiaBeam, Marina del Rey, California, USA
M. Behtouei, A. Giribono, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
A. Fukasawa, N. Majernik, J.B. Rosenzweig, O. Williams
UCLA, Los Angeles, California, USA
S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National Committee V through the ARYA project.
In this paper, we present a new class of a hybrid photoinjector in C-Band. This project is the effort result of a UCLA/Sapienza/INFN-LNF/SLAC/RadiaBeam collaboration. This device is an integrated structure consisting of an initial standing-wave 2.5-cell gun connected to a traveling-wave section at the input coupler. Such a scheme nearly avoids power reflection back to the klystron, removing the need for a high-power circulator. It also introduces strong velocity bunching due to a 90° phase shift in the accelerating field. A relatively high cathode electric field of 120 MV/m produces a ~4 MeV beam with ~20 MW input RF power in a small foot-print. The beam transverse dynamics are controlled with a ~0.27 T focusing solenoid. We show the simulation results of the RF/magnetic design and the optimized beam dynamics that shows 6D phase space compensation at 250 pC. Proper beam shaping at the cathode yields a ~0.5 mm-mrad transverse emittance. A beam waist occurs simultaneously with a longitudinal focus of <400 fs rms and peak current >600 A. We discuss application of this injector to an Inverse-Compton Scattering system and present corresponding start-to-end beam dynamics simulations.

Poster WEPAB051 [0.827 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB051

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paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 15 August 2021

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WEPAB056

Advanced Photoinjector Development at the UCLA SAMURAI Laboratory

FEL, gun, linac, simulation

2728

A. Fukasawa, G. Andonian, O. Camacho, C.E. Hansel, G.E. Lawler, W.J. Lynn, N. Majernik, P. Manwani, B. Naranjo, J.B. Rosenzweig, Y. Sakai, O. Williams
UCLA, Los Angeles, California, USA
Z. Li, R. Robles, S.G. Tantawi
SLAC, Menlo Park, California, USA
J.I. Mann
PBPL, Los Angeles, USA
M. Yadav
The University of Liverpool, Liverpool, United Kingdom

Funding: This work was supported by the US Department of Energy under the contract No. DE-SC0017648, DE-SC0009914, and DE-SC0020409, and by National Science Foundation Grant No. PHY-1549132
UCLA has recently constructed SAMURAI, a new radiation bunker and laser infrastructure for advanced accelerator research. In its first phase, we will build a 30 MeV photoinjector with an S-band hybrid gun. The beam dynamics simulation for this beamline showed the generation of the beam with the emittance 2.4 um and the peak current 270 A. FIR-FEL experiments are planned in this beamline. The saturation peak power was expected at 170 MW.

Poster WEPAB056 [0.939 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB056

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paper received ※ 28 May 2021 paper accepted ※ 01 July 2021 issue date ※ 11 August 2021

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WEPAB063

Status of the Polarized Source and Beam Preparation System at MESA

laser, electron, experiment, simulation

2736

S. Friederich, K. Aulenbacher, C. Matejcek
IKP, Mainz, Germany
K. Aulenbacher
HIM, Mainz, Germany
K. Aulenbacher
GSI, Darmstadt, Germany

Funding: This work is supported by the DFG excellence initiative PRISMA+.
The MESA Low-energy Beam Apparatus (MELBA) connects the DC photoemission source STEAM with the injector accelerator MAMBO. MELBA is capable of adjusting the longitudinal phase space for the requirements of the pre-acceleration by using a chopper and buncher while providing small transverse emittances. Measurements of the transverse phase space and longitudinal beam dimension taken at a test setup are presented. These results serve now for further improvements, e.g design changes in our corrector magnets. In addition, the revised MELBA will include two Wien filters and a solenoid for spin manipulation. A double scattering Mott polarimeter for spin diagnostics and a second source for the extraction of high bunch charges is foreseen using a branched off beam line. RF-synchronized laser diodes will be used with infrared wavelength as a driver for the spin-polarized photoemission. In this report we present the latest layout of MELBA and simulation results.

Poster WEPAB063 [1.752 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB063

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paper received ※ 19 May 2021 paper accepted ※ 16 July 2021 issue date ※ 28 August 2021

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WEPAB064

Front-to-End Simulations of the Energy Recovery Linac for the LHeC Project

electron, proton, radiation, linac

2740

K.D.J. André, B.J. Holzer
CERN, Geneva, Switzerland

The LHeC project aims to study the electron-proton deep inelastic scattering at the TeV energy scale with an innovative accelerator program. It exploits the promising energy recovery technology in order to collide an intense 50 GeV lepton beam with one hadron beam from the High Luminosity Large Hadron Collider (HL-LHC) in parallel to the hadron-hadron operation. The paper presents the studies that have been performed to assess the performance of the machine and the efficiency of the energy recovery process for different scalings of the ERL. The studies include emittance blow-up due to synchrotron radiation emission and beam-disruption created by the strong beam-beam force at the interaction point. The design principles of the ERL structure are discussed, including the particle detector bypass and the interaction region, and the results of the tracking simulations are presented, considering the complete multi-turn ERL process. Special attention is turned to the lepton beam emittance budget and the resulting energy recovery performance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB064

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paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 28 August 2021

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WEPAB067

High Duty Cycle EUV Radiation Source Based on Inverse Compton Scattering

laser, electron, gun, photon

2748

R. Huang, Q.K. Jia, C. Li
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by the National Natural Science Foundation of China Grant Number 11805200, and National Key Research and Development Program of China No. 2016YFA0401901.
ICS can obtain quasi-monochromatic and directional EUV radiation via a MeV-scale energy electron beam and a micron-scale wavelength laser beam, which enables a dramatic reduction in dimension and expense of the system, and makes it an attractive technology in research, industry, medicine and homeland security. Here we describe an EUV source based on high repetition ICS system. The scheme exploits the output from the laser-electron interaction between a MW-ps laser at MHz repetition-rate and a high quality electron beam with an energy of a few MeV at MHz repetition-rate.

Poster WEPAB067 [1.551 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB067

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paper received ※ 23 May 2021 paper accepted ※ 24 June 2021 issue date ※ 02 September 2021

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WEPAB074

A Distributed Sextupoles Lattice for the ALBA Low Emittance Upgrade

lattice, sextupole, injection, optics

2762

G. Benedetti, M. Carlà, U. Iriso, Z. Martí, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

The first lattice studied in 2019 for the ALBA upgrade was a 7BA lattice with two dispersion bumps, for localised chromatic correction. That lattice had limited dynamic aperture and momentum acceptance. In 2020 we started to explore a different approach to find an MBA lattice with distributed chromatic correction that meets the same emittance goal with larger dynamic aperture and momentum acceptance. The choice of the number of bendings per cell, as well as the tuning of the magnet gradients, is carried out by developing a light weight solver that performs both the emittance and chromaticity optimisation of the arcs and the matching of the linear optics in the straight sections. We present the status of the storage ring upgrade studies, the performance of the new developed lattice, together with the issues related with the injection scheme.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB074

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paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 22 August 2021

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WEPAB088

Transverse Beam Emittance Measurement by Undulator Radiation Power Noise

radiation, undulator, optics, synchrotron

2794

I. Lobach
University of Chicago, Chicago, Illinois, USA
A. Halavanau, Z. Huang
SLAC, Menlo Park, California, USA
K. Kim
ANL, Lemont, Illinois, USA
V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA

Generally, turn-to-turn power fluctuations of incoherent spontaneous synchrotron radiation in a storage ring depend on the 6D phase-space distribution of the electron bunch. In some cases, if only one parameter of the distribution is unknown, this parameter can be determined from the measured magnitude of these power fluctuations. In this contribution, we report the results of our experiment at the Integrable Optics Test Accelerator (IOTA) storage ring, where we carried out an absolute measurement (no free parameters or calibration) of a small vertical emittance (5–15 nm rms) of a flat beam by this new method, under conditions, when the small vertical emittance is unresolvable by a conventional synchrotron light beam size monitor.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB088

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paper received ※ 17 May 2021 paper accepted ※ 24 June 2021 issue date ※ 12 August 2021

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WEPAB103

Systematic Beam Parameter Studies at the Injector Section of FLUTE

laser, cathode, electron, quadrupole

2837

T. Schmelzer, E. Bründermann, D. Hoffmann, I. Križnar, S. Marsching, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski, T. Windbichler
KIT, Karlsruhe, Germany

Funding: This work is supported by the DFG-funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology (KSETA)"
FLUTE (Ferninfrarot Linac- und Test-Experiment) is a compact linac-based test facility for accelerator R&D and source of intense THz radiation for photon science. In preparation for the next experiments, the electron beam of the injector section of FLUTE has been characterized. In systematic studies the electron beam parameters, e.g., beam energy and emittance, are measured with several diagnostic systems. This knowledge allows the establishment of different operation settings and the optimization of electron beam parameters for future experiments.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB103

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paper received ※ 19 May 2021 paper accepted ※ 01 September 2021 issue date ※ 13 August 2021

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WEPAB111

Controlled Degradation by Oxygen Exposure in the Performance of a Ag (100) Single-Crystal Photocathode

cathode, experiment, electron, cryogenics

2856

L.A.J. Soomary, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
L.B. Jones, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The search for high-performance photocathode electron sources is a priority in the accelerator science community. The surface characteristics of a photocathode define many important factors of the photoemission including the work function, intrinsic emittance, and quantum efficiency of the photocathode. These factors in turn define the electron beam performance which is measurable as normalized emittance, brightness, and energy spread*. Strategies for improving these parameters vary, but understanding and influencing the relevant cathode surface physics which underpin these attributes is a primary focus for the electron source community**. As such, pure metal photocathodes and their performance at UV wavelengths are of interest as seen at the LCLS at SLAC and CLARA at Daresbury. We present performance data for an Ag (100) single-crystal photocathode under illumination at 266 nm wavelength, with known levels of surface roughness, using our Transverse Energy Spread Spectrometer (TESS)*** both at room and cryogenic temperatures. Crucially our data shows the effect of progressive degradation in the photo-cathode performance as a consequence of exposure to controlled levels of oxygen.
* D.H. Dowell, et al., Nucl. Instr. and Meth. A (2010), doi:10.1016/j.nima.2010.03.104
** Appl. Phys. Lett. 89, 224103 (2006); doi:10.1063/1.2387968
*** Proc. FEL’13, TUPPS033, 290-293

Poster WEPAB111 [0.866 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB111

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paper received ※ 20 May 2021 paper accepted ※ 22 June 2021 issue date ※ 31 August 2021

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WEPAB112

Performance Characterisation of a Cu (100) Single-Crystal Photocathode

cathode, electron, experiment, photon

2860

L.A.J. Soomary, D.P. Juarez-Lopez, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
L.B. Jones, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The search for high performance photocathode electron sources is a priority in the accelerator science community. The surface characteristics of a photocathode define important factors of the photoemission including the intrinsic emittance, the quantum efficiency and the work function of the photocathode. These factors in turn define the electron beam performance which are measurable as emittance, brightness and energy spread. We have used ASTeC’s Multiprobe (SAPI)* to characterise and analyse photocathode performance using multiple techniques including XPS, STM, and LEED imaging, and their Transverse Energy Spread Spectrometer (TESS)** to measure mean transverse energy (MTE). We present characterisation measurements for a Cu (100) single-crystal photocathode sample with data from SAPI confirming the crystallographic face and showing surface composition and roughness, supported by data from TESS showing the photocathode electron beam energy spread.
* B.L. Militsyn, 4-th EuCARD2 WP12.5 meeting, Warsaw, 14-15 March 2017
**Proc. FEL’13, TUPPS033, 290-293

Poster WEPAB112 [0.814 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB112

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 22 August 2021

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WEPAB163

An X-Band Ultra-High Gradient Photoinjector

gun, experiment, linac, solenoid

2986

S.V. Kuzikov, S.P. Antipov, P.V. Avrakhov, E. Dosov, C.-J. Jing, E.W. Knight
Euclid TechLabs, Solon, Ohio, USA
G. Ha, C.-J. Jing, W. Liu, P. Piot, J.G. Power, D.S. Scott, J.H. Shao, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid Beamlabs, Bolingbrook, USA
X. Lu
MIT/PSFC, Cambridge, Massachusetts, USA
X. Lu
SLAC, Menlo Park, California, USA
P. Piot
Fermilab, Batavia, Illinois, USA
P. Piot, W.H. Tan
Northern Illinois University, DeKalb, Illinois, USA
E.E. Wisniewski
IIT, Chicago, Illinois, USA

Funding: This work was supported by DoE SBIR grant # DE-SC0018709.
High brightness beams appealing for XFELs and UEM essentially imply a high current and a low emittance. To obtain such beams we propose to raise the accelerating voltage in the gun mitigating repealing Coulomb forces. An ultra-high gradient is achieved utilizing a short-pulse technology. We have designed a room temperature X-band 1,5 cell gun that is able to inject 4 MeV, 100 pC bunches with as low as 0.15 mcm normalized transverse emittance. The gun is operated with as high gradients as 400 MV/m and fed by 200 MW, 10 ns RF pulses generated with Argonne Wakefield Accelerator (AWA) power extractor. We report results of low RF power tests, laser alignment test results, and successful gun conditioning results carried out at nominal RF power.

Poster WEPAB163 [5.427 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB163

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paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 19 August 2021

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WEPAB169

Towards Ultra-Smooth Alkali Antimonide Photocathode Epitaxy

lattice, cathode, interface, electron

3001

E.J. Montgomery
Private Address, Bolingbrook, USA
O. Chubenko, G.S. Gevorkyan, S.S. Karkare, P. Saha
Arizona State University, Tempe, USA
R.G. Hennig, J.T. Paul
University of Florida, Gainesville, Florida, USA
C. Jing, S. Poddar
Euclid Beamlabs, Bolingbrook, USA
H.A. Padmore
LBNL, Berkeley, California, USA

Funding: Work supported by Department of Energy, Office of Science, Office of Basic Energy Sciences, under grant number DE-SC0020575.
Photocathodes lead in brightness among electron emitters, but transverse momenta are unavoidably nonzero. Ultra-low transverse emittance would enable brighter, higher energy x-ray free-electron lasers (FEL), improved colliders, and more coherent, detailed ultrafast electron diffraction/microscopy (UED/UEM). Although high quantum efficiency (QE) is desired to avoid laser-induced nonlinearities, the state-of-the-art is 100 pC bunches from copper, 0.4 mm-mrad emittance. Advances towards 0.1 mm-mrad require ultra-low emittance, high QE, cryo-compatible materials. We report efforts towards epitaxial growth of cesium antimonide on lattice matched substrates. DFT calculations were performed to downselect from a list of candidate lattice matches. Co-evaporations achieving >3% QE at 532 nm followed by atomic force and Kelvin probe microscopy (AFM and KPFM) show ultra-low 313 pm rms (root mean square) physical and 2.65 mV rms chemical roughness. We simulate roughness-induced mean transverse energy (MTE) to predict <1 meV from roughness effects at 10 MV/m in as-grown optically thick cathodes, promising low emittance via epitaxial growth.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB169

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 11 August 2021

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WEPAB175

Simulation Study of Electron Beam Acceleration with Non-Gaussian Transverse Profiles for AWAKE Run 2

plasma, electron, acceleration, wakefield

3012

L. Liang, G.X. Xia
The University of Manchester, Manchester, United Kingdom
J.P. Farmer
MPI-P, München, Germany
L. Liang, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The authors would like to acknowledge the support from the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1
In the physics plan for AWAKE Run 2, two known effects, beam loading the longitudinal wakefield and beam matching to the pure plasma ion channel, will be implemented for the better control of electron acceleration. It is founded in our study of beam matching that the transverse profile of the initial witness beam have a significant impact on its acceleration quality. In this paper, particle-in-cell (PIC) simulations are used to study factors that affect the acceleration quality of electron beams with different transverse profiles.

Poster WEPAB175 [1.860 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB175

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paper received ※ 10 May 2021 paper accepted ※ 25 June 2021 issue date ※ 02 September 2021

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WEPAB189

EIC Hadron Beamline Vacuum Studies

vacuum, hadron, electron, cryogenics

3060

D. Weiss, M. Mapes, J.E. Tuozzolo, S. Verdú-Andrés
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Ninety percent of the EIC hadron ring beamline is cold-bore comprising strings of interconnected 4.55 K RHIC superconducting (SC) magnets. The EIC operating specification requires shorter bunches and 3x higher intensity beams which are not appropriate for the present RHIC stainless steel cold-bore beam tube. The intensity and emittance of the hadron beams will degrade due to interactions with residual gas or vacuum instabilities arising from the expected resistive-wall (RW) heating, electron clouds, and beam-induced desorption mechanisms. Without strategies to limit RW heating, major cryogenic system modifications are needed to prevent SC magnet quenches. The SC magnet cold-bore beam tubes will be equipped with a high RRR copper clad stainless steel sleeve to significantly reduce RW heating and so the effect on the SC magnet cryogenic heat load and temperature. A thin amorphous carbon film applied to the beam facing copper surface will suppress electron cloud formation. This paper discusses the vacuum requirements imposed by the EIC hadron beams and the plans to achieve the necessary vacuum and thermal stability that ensure acceptable beam quality and lifetime.

Poster WEPAB189 [3.321 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB189

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paper received ※ 17 May 2021 paper accepted ※ 25 August 2021 issue date ※ 26 August 2021

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WEPAB198

Beam Dynamics Design of a Synchrotron Injector with Laser-Accelerated Ions

laser, synchrotron, quadrupole, simulation

3085

M.Z. Tuo, X. Guan, W. Lu, P.F. Ma, Y. Wan, X.W. Wang, Q.Z. Xing, H.J. Yao, S.X. Zheng
TUB, Beijing, People’s Republic of China

We present, in this paper, the beam dynamics design of a linac injector with laser-accelerated carbon-ions for a medical synchrotron. In the design, the initial transverse divergence is reduced by two apertures. The beam is focused transversely through a quadrupole triplet lens downstream the apertures. The output energy spread of the extracted beam at the exit of the injector is compressed from ±6% to ±0.6% by a debuncher and a bend magnet system to meet the injection requirement for the synchrotron. By changing the width of imaging slit of the bend magnet system, the beam with energy of 4±0.024 MeV/u is extracted, and the particle number per shot and transverse emittances of the beam at the exit of the injector can be regulated through adjusting the slit height. The dynamics design can pave the way for the future concept research of the synchrotron injector.

Poster WEPAB198 [1.034 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB198

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paper received ※ 16 May 2021 paper accepted ※ 16 June 2021 issue date ※ 18 August 2021

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WEPAB204

Layout of the New Septum Magnets for Fast Extraction in J-PARC Main Ring

septum, extraction, operation, simulation

3103

S. Iwata, K. Ishii, H. Matsumoto, N. Matsumoto, Y. Sato, T. Shibata, T. Sugimoto
KEK, Ibaraki, Japan

At J-PARC Main Ring (MR), we are pursuing to improve the beam power from 500 kW to 1.3 MW by reducing the repetition cycle from 2.48 to 1.16 seconds (1 Hz operation). Additionally, we are considering the beam particles increasing by selecting a more optimal tune. The fast extraction (FX) equipment to the neutrino facility (NU) is needed to upgrade for the 1 Hz operation. We plan to replace most FX septum magnets with new ones in 2021. We report a layout of the FX line in confirmation of new beam optics and mention the beam loss during the fast extraction.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB204

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paper received ※ 20 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021

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WEPAB210

Beam Commissioning of the New 160 MeV H⁻ Injection System of the CERN PS Booster

injection, simulation, scattering, brightness

3116

E. Renner, S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, G.P. Di Giovanni, L.O. Jorat, E.H. Maclean, M. Meddahi, B. Mikulec, T. Prebibaj, G. Rumolo, P.K. Skowroński, W.J.M. Weterings
CERN, Meyrin, Switzerland

A key component to meeting the brightness targets of the LHC Injectors Upgrade (LIU) project at CERN is the new 160 MeV H⁻ charge exchange injection system into the Proton Synchrotron Booster. This system has been in beam commissioning since December 2020, optimizing the beam production schemes for tailoring different beams to the respective user-defined brightness targets. In this paper, selected measurements from the beam commissioning period are presented, characterizing the system’s flexibility to produce the required wide range of transverse emittances. The discussion focuses on the essential optimization of the injection set-up to minimize space charge driven emittance blow-up and injection errors. The results are completed by selected comparisons with multi-particle simulation models of the injection process.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB210

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paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 29 August 2021

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WEPAB215

Simulation of Intra-Beam Scattering in PyHEADTAIL

scattering, simulation, space-charge, proton

3134

V. Rodin, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
A. Oeftiger
GSI, Darmstadt, Germany
V. Rodin, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 721559
High-intensity beams in low-energy synchrotrons are subject to space charge as well as intra-beam scattering (IBS). Accurate modelling of both effects becomes essential when the transverse emittances and minimum bunch length are determined through heating processes and resonances induced by machine errors. To date, only very few tools available to the general public allow to simultaneously study space charge and IBS in self-consistent simulations. In this contribution, we present our recent development of an IBS module for PyHEADTAIL, an open-source 6D multi-particle tracking tool, which already includes various 2.5D and 3D space-charge models based on the self-consistent particle-in-cell algorithm. A simulation example of high-intensity bunch rotation demonstrates the joint impact of applied heating effects. Our model is based on the Martini and Bjorken-Mitingwa theories. Benchmarks of our implementation against IBS modules provided in the MAD-X and JSPEC codes are shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB215

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paper received ※ 23 May 2021 paper accepted ※ 14 July 2021 issue date ※ 13 August 2021

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WEPAB227

Mechanism of Longitudinal Single-Bunch Instability in the CERN SPS

impedance, simulation, synchrotron, coupling

3161

I. Karpov
CERN, Meyrin, Switzerland
M. Gadioux
UCD, Dublin, Ireland

Understanding the origin of beam instabilities is essential for reaching the highest performance of proton synchrotrons. In the present work, the Oide-Yokoya eigenvalue method of solving the linearised Vlasov equation was used to shed light on the mechanism of longitudinal single-bunch instability in the CERN SPS. In particular, semi-analytical calculations were done for the full longitudinal impedance model, taking into account the RF nonlinearity. The obtained results agree well with macro-particle simulations and are consistent with available beam measurements. For the first time, the instability has been interpreted as a coupling of radial modes within a single azimuthal mode, due to a strong potential-well distortion of the synchrotron-frequency distribution. To avoid this instability, a higher RF voltage is required at a given emittance. Thus, the instability mechanism is very different from the loss of Landau damping, which, in contrast, is mitigated by a lower RF voltage. This understanding also allowed us to optimise the RF voltage programmes during the acceleration cycle for high-intensity bunches used in the AWAKE experiment at CERN.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB227

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paper received ※ 12 May 2021 paper accepted ※ 01 July 2021 issue date ※ 15 August 2021

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WEPAB234

Simulating Two Dimensional Coherent Synchrotron Radiation in Python

simulation, radiation, synchrotron-radiation, electron

3177

W. Lou, Y. Cai, C.E. Mayes, G.R. White
SLAC, Menlo Park, California, USA

Coherent Synchrotron Radiation (CSR) in bending magnets poses an important limit for electron beams to reach high brightness in novel accelerators. While the longitudinal wakefield has been well studied in one-dimensional CSR theory and implemented in various simulation codes, transverse wakefields have received less attention. Following the recently developed two-dimensional CSR theory, we developed a Python code simulating the steady-state two-dimensional CSR effects. The computed CSR wakes have been benchmarked with theory and other simulation codes. To speed up computation speed, the code applies vectorization, parallel processing, and Numba in Python.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB234

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paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 20 August 2021

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WEPAB243

Longitudinal Microwave Instability Study at Transition Crossing with Ion Beams in the CERN PS

impedance, simulation, controls, proton

3197

A. Lasheen, H. Damerau, A. Huschauer, B.K. Popovic
CERN, Meyrin, Switzerland

The luminosity of lead ion collisions in the Large Hadron Collider (LHC) was significantly increased during the 2018 ion run by reducing the bunch spacing from 100 ns to 75 ns, allowing to increase the total number of bunches. With the new 75 ns variant, three instead of four bunches are generated each cycle in the Low Energy Ion Ring (LEIR) and the Proton Synchrotron (PS) with up to 30% larger intensity per bunch. The beam was produced with satisfactory quality but at the limit of stability in the injectors. In particular, the minimum longitudinal emittance in the PS is limited by a strong longitudinal microwave instability occurring just after transition crossing. The uncontrolled blow-up generates tails, which translate into an unacceptably large satellite population following the RF manipulations prior to extraction from the PS. In this paper, instability measurements are compared to particle simulations using the latest PS impedance model to identify the driving impedance sources. Moreover, means to mitigate the instability are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB243

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paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 29 August 2021

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WEPAB248

Kurth Vlasov-Poisson Solution for a Beam in the Presence of Time-Dependent Isotropic Focusing

focusing, space-charge, simulation, proton

3213

C.E. Mitchell, K. Hwang, R.D. Ryne
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The well-known K-V distribution provides an exact solution of the self-consistent Vlasov-Poisson system describing an unbunched charged particle beam with nonzero temperature in the presence of time-dependent linear transverse focusing. We describe a lesser-known exact solution of the Vlasov-Poisson system that is based on the work of Kurth in stellar dynamics. Unlike the K-V distribution, the Kurth distribution is a true function of the phase space variables, and the solution may be constructed on either the 4D or 6D phase space, for the special case of isotropic linear focusing. Numerical studies are performed for benchmarking simulation codes, and the stability properties of a 4D Kurth distribution are compared with those of a K-V distribution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB248

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 02 September 2021

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WEPAB249

Model of Curvature Effects Associated with Space Charge for Long Beams in Dipoles

space-charge, vacuum, dipole, shielding

3217

C.E. Mitchell, K. Hwang, R.D. Ryne
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
For modeling the dynamics within a dipole of a bunch whose length is much larger than the vacuum pipe radius, it is typical to use a 2D (or 2.5D) Poisson solver, with arc length taken as the independent variable. However, sampled at a fixed time, the beam is curved, space charge is not truly 2D, and the usual cancellation between E and B contributions to the Lorentz force need not exactly hold. The size of these effects is estimated using an idealized model of a uniform torus of charge rotating inside a toroidal conducting pipe. Simple expressions are provided for the correction of the electric and magnetic fields to first order in the reciprocal of the curvature radius.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB249

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paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 02 September 2021

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WEPAB250

Interplay Between Space Charge, Intra-Beam Scattering, and Synchrotron Radiation Effects

resonance, space-charge, damping, synchrotron

3220

M. Zampetakis, F. Antoniou, H. Bartosik, Y. Papaphilippou
CERN, Geneva, Switzerland
M. Zampetakis
University of Crete, Heraklion, Crete, Greece

The objective of this research is to study the interplay of synchrotron radiation, intra-beam scattering, and space charge in the vicinity of excited resonances. In this respect, two modules were developed to simulate intra-beam scattering and synchrotron radiation effects and plugged into pyORBIT to be used together with its space charge module. Different regimes of synchrotron motion were used to study the response of the beam to a lattice resonance when space charge, intra-beam scattering and synchrotron radiation are present.

Poster WEPAB250 [0.536 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB250

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paper received ※ 17 May 2021 paper accepted ※ 21 July 2021 issue date ※ 25 August 2021

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WEPAB251

Beam Dynamics Optimization of LCLS-II HE Linear Accelerator Design

electron, undulator, radiation, FEL

3224

J. Qiang
LBNL, Berkeley, California, USA
T.O. Raubenheimer, M.D. Woodley
SLAC, Menlo Park, California, USA

The LCLS-II-HE as a high energy upgrade of the high repetition rate X-ray FEL under construction at SLAC will provide great opportunities for scientific discovery by generating coherent, high brightness hard X-ray radiation. In this paper, we report on beam dynamics optimization of the LCLS-II HE linear accelerator design with a 100pC and a 20pC charge beam to attain high quality electron beam for X-ray FEL radiation. We also present preliminary results of beam dynamics optimization of a 100pC beam from a low emittance superconducting injector.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB251

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paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021

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WEPAB252

Transient Beam-Beam Effect During Electron Bunch Replacement in the EIC

electron, proton, injection, simulation

3228

J. Qiang
LBNL, Berkeley, California, USA
M. Blaskiewicz, Y. Luo, C. Montag, F.J. Willeke, D. Xu
BNL, Upton, New York, USA
Y. Hao
FRIB, East Lansing, Michigan, USA

The high luminosity, high polarization electron-ion collider (EIC) will provide great opportunities in nuclear physics study. In order to maintain high polarization, the electron beam will be replaced every few minutes during the collider operation. This frequent replacement of electron beams can affect proton beam quality during the collision. In this paper, we report on the study of the transient effect of electron beam replacement on proton beam emittance growth through strong-strong beam-beam simulation. The effect of electron beam injection imperfection will be included in the study.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB252

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paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 02 September 2021

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WEPAB256

Three-Dimensional Space Charge Oscillations in a Hybrid Photoinjector

plasma, simulation, electron, cathode

3240

M. Carillo, M. Behtouei, F. Bosco, L. Faillace, A. Giribono, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
L. Ficcadenti
INFN-Roma, Roma, Italy
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy

Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
A new hybrid C-band photo-injector, consisting of a standing wave RF gun connected to a traveling wave structure, operating in a velocity bunching regime, has shown to produce an extremely high brightness beam with very low emittance and a very high peak current through a simultaneous compression of the beam in the longitudinal and transverse dimensions. A beam slice analysis has been performed in order to understand the evolution of the relevant physical parameters of the beam in the longitudinal and transverse phase spaces along the structure. A simple model for the envelope equation has been developed to describe the beam behavior in this particular dynamics regime that we term "triple waist", since all three dimensions reach a minimum condition almost simultaneously. The model analyzes the transverse envelope dynamics at the exit of the hybrid photo-injector, in the downstream drift where the triple waist occurs. The analytical solutions obtained from the envelope equation are compared with the simulations, showing a good agreement. Finally, these results have been analyzed also in terms of plasma oscillation to obtain a further physical interpretation of the beam dynamics.

Poster WEPAB256 [1.162 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB256

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paper received ※ 19 May 2021 paper accepted ※ 21 July 2021 issue date ※ 13 August 2021

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WEPAB258

Beam Dynamics Design of a 162.5 MHz Superconducting RFQ Accelerator

rfq, cavity, accelerating-gradient, focusing

3248

Ying. Xia, H.P. Li, Y.R. Lu, Q.Y. Tan, Z. Wang
PKU, Beijing, People’s Republic of China
Y.R. Lu
IAP, Frankfurt am Main, Germany

Superconducting(SC) RFQ has lower power consumption, larger aperture and higher accelerating gradient than room temperature RFQ. We plan to design a 162.5MHz SC RFQ to accelerate the 30 mA proton beams from 35 keV to 2.5 MeV, which will be used as a neutron source for BNCT and neutron imaging project. At an inter-vane voltage of 180kV, the beam dynamics design was carried out with acceptable peak surface electric field, high transmission efficiency, and relatively short cavity length.

Poster WEPAB258 [1.251 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB258

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paper received ※ 17 May 2021 paper accepted ※ 06 July 2021 issue date ※ 14 August 2021

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WEPAB263

Complex Unit Lattice Cell for Low-Emittance Synchrotrons

lattice, sextupole, focusing, synchrotron

3254

Z.L. Ren, Z.H. Bai, J.J. Tan, L. Wang, H. Xu, P.H. Yang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

To reach the real diffraction-limited emittance, it is generally required to increase the number of bends in multi-bend achromat (MBA) lattices that are used in the designs of fourth-generation synchrotron light sources. For an MBA lattice with distributed chromatic correction, more bends mean much tighter space and much stronger magnets. Inspired by the hybrid MBA lattice concept, in this paper we propose a new lattice concept called complex unit lattice cell, which can save space and reduce magnet strengths. A 17BA lattice based on the complex unit cell concept is designed for a 3 GeV synchrotron light source with a circumference of 537.6 m, which reaches a natural emittance of about 21 pm·rad. Comparison is also made between this 17BA lattice and the 17BA lattice with distributed chromatic correction to demonstrate the merit of the complex unit cell concept.

Poster WEPAB263 [1.279 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB263

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paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 12 August 2021

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WEPAB264

MOGA Optimization of Superconducting Longitudinal Gradient Bend Based on NbTi Wire

solenoid, lattice, storage-ring, radiation

3257

C. Chen, Z.H. Bai, G.Y. Feng, Z.L. Ren, Zh.X. Tang, L. Wang, H. Xu
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Key Research and Development Program of China, (2016YFA0402001)
Multi-bend achromat lattices with unit cells have been used in diffraction-limited storage ring designs. The longitudinal gradient bend can reduce the horizontal emittance below the theoretical minimum of a given magnet structure, and generally the horizontal emittance reduces with the peak field grows. Therefore superconducting longitudinal gradient bend (SLGB) can produce higher peak field value and quasi-hyperbolic field profile to minimize emittance at location of radiation and generate better hard X-rays. NbTi conductor, rather than Nb₃Sn conductor, is selected to keep the design and manufacture of SLGB magnet as simple as possible. In this paper, how the field profiles of race-track type coil and solenoid coil change with their geometric parameters is studied, and multi-objective genetic algorithm is used to optimize SLGB magnet structure considering Hefei Advanced Light Facility lattice design demand and NbTi critical current.

Poster WEPAB264 [1.476 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB264

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paper received ※ 14 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021

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WEPAB266

Simulation Studies of Plasma Cascade Amplifier

electron, simulation, plasma, experiment

3265

J. Ma, V. Litvinenko, G. Wang
BNL, Upton, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Plasma cascade amplifier (PCA) is an advanced design of amplifier for the coherent electron cooling (CeC) experiment in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Working principle of PCA is the new plasma cascadeμbunching instability occurring in electron beams propagating along a straight trajectory. PCA is cost-effective as it does not require separating electron and hadron beams. SPACE, a parallel, relativistic 3D electromagnetic Particle-in-Cell (PIC) code, has been used for simulation studies of PCA.

Poster WEPAB266 [2.317 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB266

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paper received ※ 13 May 2021 paper accepted ※ 10 June 2021 issue date ※ 31 August 2021

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WEPAB271

Numerical Modelling of the Optical Stochastic Cooling Experiment at IOTA

simulation, radiation, damping, undulator

3273

A.J. Dick, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J.D. Jarvis
Fermilab, Batavia, Illinois, USA
P. Piot
ANL, Lemont, Illinois, USA

Funding: CBB NSF-PHY-1549132 DOE DE-SC0018656 DOE DE-AC02-07CH11359
A proof-of-principle optical-stochastic cooling (OSC) experiment is currently in its commissioning phase at the Fermilab’s IOTA ring. In support of this experiment, we recently implemented an OSC element in the ELEGANT tracking program. The model, based on a semi-analytic description of OSC [*], supports the simulation of a large number of macroparticles (10⁴-10⁶) over many turns (10⁶). This paper showcases the simulation capabilities to investigate the beam dynamics in the presence of cooling (or self-interacting radiation field in general) and quantify the impact of various sources of error (e.g. transverse and phase jitter), guide data analysis.
* B. Andorf, V. A. Lebedev, J. Jarvis, and P. Piot Rev. Accel. Beams 21, 100702 (2018)

Poster WEPAB271 [1.649 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB271

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paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 13 August 2021

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WEPAB272

Field-Off Multiple Coulomb Scattering in the MICE Liquid Hydrogen Absorber

experiment, scattering, beam-cooling, radiation

3277

G.T. Chatzitheodoridis
USTRAT/SUPA, Glasgow, United Kingdom

It is anticipated that high brightness muon beams will be used primarily in two types of accelerators, a muon collider and a neutrino factory. The primary challenge posed by using muons as the working particle of an accelerator physics system, and the reason it has not been used extensively in modern particle physics experiments, is its short life-time (2.2μseconds at rest) and the relatively long cooling periods required by current cooling techniques. The Muon Ionization Cooling Experiment (MICE), is a multi-national accelerator physics initiative which has demonstrated Ionization Cooling (IC); a new, rapid beam-cooling technique suitable for the short-lived muon. The performance of IC depends on two key processes - energy loss due to collisional ionization, and Multiple Coulomb Scattering (MCS) - for which accurate models are crucial in parametrizing the method and enabling quantitative design of future muon accelerators. Experimental measurements of MCS of positive straight-track muons with momenta in the range 170-240 MeV/c in liquid H₂ are reported in this study.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB272

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paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 31 August 2021

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WEPAB277

Transverse Emittance Change and Canonical Angular Momentum Growth in MICE ‘Solenoid Mode’ with Muon Ionization Cooling

solenoid, detector, focusing, collider

3289

T.W. Lord
University of Warwick, Coventry, United Kingdom

Emittance reduction of muon beams is an important requirement in the design of a Neutrino Factory or Muon Collider. Ionization cooling, whereby beam emittance is reduced by passing a beam through an energy-absorbing material, requires tight focusing in the transverse plane which is achieved in many designs using solenoid focusing. In solenoid focusing, the beam acquires kinetic angular momentum due to the radial field in the solenoid fringe. Cooling in ‘flip’ mode, where the beam-focusing solenoid field changes polarity at the absorber, has already been demonstrated in the Muon Ionization Cooling Experiment (MICE). In this mode the absorber is near to the field flip, so the kinetic angular momentum is zero at the absorber. ‘Solenoid mode’ cooling, where the field polarity does not change across the absorber leading to a beam crossing the absorber with significant kinetic angular momentum, has been considered for the final section of the muon collider design due to potentially stronger focussing that it enables. In this paper, we present the performance of MICE in ‘solenoid mode’.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB277

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paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 12 August 2021

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WEPAB306

Applying Machine Learning to Optimization of Cooling Rate at Low Energy RHIC Electron Cooler

electron, simulation, network, experiment

3391

Y. Gao, K.A. Brown, P.S. Dyer, S. Seletskiy, H. Zhao
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.
The Low Energy RHIC electron Cooler (LEReC) is a novel, state-of-the-art, electron accelerator for cooling RHIC ion beams, which was recently built and commissioned. Optimization of cooling with LEReC requires fine-tuning of numerous LEReC parameters. In this work, initial optimization results of using Machine Learning (ML) methods - Bayesian Optimization (BO) and Q-learning are presented. Specially, we focus on exploring the influence of the electron trajectory on the cooling rate. In the first part, simulations are conducted by utilizing a LEReC simulator. The results show that both methods have the capability of deriving electron positions that can optimize the cooling rate. Moreover, BO takes fewer samples to converge than the Q-learning method. In the second part, Bayesian optimization is further trained on the historical cooling data. In the new samples generated by the BO, the percentage of larger cooling rates data is greatly enhanced compared with the original historical data.

Poster WEPAB306 [1.083 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB306

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paper received ※ 12 May 2021 paper accepted ※ 01 July 2021 issue date ※ 24 August 2021

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WEPAB335

Aluminum Vacuum Chamber for the Sirius DELTA 52 Undulator

vacuum, undulator, storage-ring, synchrotron

3463

T.M. Rocha, O.R. Bagnato, R.O. Ferraz, H.G. Filho, P.P.S. Freitas, G.R. Gomes, P.H. Lima, R.F. Oliveira, B.M. Ramos, F. Rodrigues, R.M. Seraphim, D.R. Silva, M.B. Silva
LNLS, Campinas, Brazil

Sirius is a 3 GeV fourth generation synchrotron light source under commissioning by the Brazilian Synchrotron Light Laboratory (LNLS). Delta Undulators with magnet vertical aperture of 13.6 mm, and period of 52.5 mm will be used for the generation of soft X rays to photoemission spectroscopy and X ray absorption experiments. Extruded aluminum vacuum chambers having small vertical aperture of 7.6 mm and horizontal aperture of 13 mm is proposed. This paper details the design and manufacturing processes of a complete chamber. Challenges regarding the TIG welding for aluminum and NEG coating for small aperture chambers will also be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB335

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paper received ※ 18 May 2021 paper accepted ※ 19 July 2021 issue date ※ 20 August 2021

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WEPAB370

Study of an L-Band CW Linac

electron, radiation, linac, solenoid

3575

J. Gao, H.B. Chen, J.Y. Liu, J. Shi, H. Zha
TUB, Beijing, People’s Republic of China

We have studied an L-band linac based on a cheap industrial magnetron, which works at CW mode with 75kW averaged output-power. The designed energy-gain of electrons is 500keV. Low accelerating gradient was the dominant problem encountered during the structure design. We adopted a standing-wave structure with magnetically coupling and nose cones to increase the effective shunt impedance. A 7-cell design has been completed, of which the transverse dynamics and thermodynamics were simulated. Results showed that this accelerating structure could work stably at 59 C and 100 mA output beam current was achieved. This L-band design provided a cheap and efficient way to generate low-energy electrons for industrial irradiation processing.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB370

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 19 August 2021

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WEPAB385

Beam Dynamic Analysis of RF Modulated Electron Beam Produced by Gridded Thermionic Guns

electron, gun, cathode, linac

3618

G. Adam
University of Strathclyde, Glasgow, United Kingdom
A.W. Cross, L. Zhang
USTRAT/SUPA, Glasgow, United Kingdom
B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
B.L. Militsyn
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Science and Technology Facilities Council (STFC) U.K training grant, industrial case with TMD Ltd, UK ST/R002141/1 "Accelerators for Security, healthcare and Environmental applications ".
A thermionic cathode gridded electron gun used in injectors for different types of circular and linear particle accelerators and for energy recovery configurations was studied. Both theory and numerical simulation were used to explore the relationship between the bunch charge and bunch length. The electron gun is based on a Pierce-type geometry. It was initially designed using Vaughan synthesis followed by optimization using a 2D electron trajectory solver TRAK. After optimization, the grid in front of the cathode was inserted and the RF field was introduced through a coaxial waveguide structure. The complete gun was simulated using the PIC code MAGIC. High duty cycle operations at frequencies 1.5 GHz and 3.0 GHz, were investigated using different combinations of both the bias and the RF voltage applied between the cathode and the grid. The beam dynamics results from the PIC showed that a minimum bunch length of 10⁶ ps could be achieved with a bunch charge of 33 pC when the driving RF frequency was 1.5 GHz. Operating at the higher RF frequency of 3GHz did not significantly reduce the bunch length. The normalized emittance of about 5.6 mm-mrad was demonstrated in PIC simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB385

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paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 30 August 2021

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THXA06

The Effect of Beam Velocity Distribution on Electron-Cooling at Elena

electron, proton, antiproton, simulation

3700

B. Veglia, A. Farricker, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
A. Farricker
UMAN, Manchester, United Kingdom
B. Veglia, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by EU Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559.
ELENA is a novel storage ring at CERN, designed to deliver low energy, high-quality antiprotons to antimatter experiments. The electron cooler is a key component of this decelerator, which counters the beam blow-up as the antiproton energy is reduced from 5.3 MeV to 100 keV. Typical numerical approximations on electron cooling processes assume that the density distribution of electrons in analytical form and the velocity distribution space to be Maxwellian. However, it is useful to have an accurate description of the cooling process based on a realistic electron distribution. In this contribution, BETACOOL simulations of the ELENA antiproton beam phase space evolution were performed using uniform, Gaussian, and "hollow beam" electron velocity distributions. The results are compared with simulations considering a custom electron beam distribution obtained with G4beamline. The program was used to simulate the interaction of an initially Gaussian electron beam with the magnetic field measured inside the electron cooler interaction chamber. The resulting beam lifetime and equilibrium parameters are then compared with measurements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA06

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paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 14 August 2021

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THXA07

Driven 3D Beam Oscillations for Optics Measurements in Synchrotrons

optics, dipole, synchrotron, betatron

3704

L. Malina, J.M. Coello de Portugal, H. Timko, R. Tomás García
CERN, Geneva, Switzerland

Optics measurements in storage rings employ turn-by-turn data of transversely excited beams. Traditionally, to measure chromatic properties, the relative momentum is changed step-wise, which is time-consuming and almost impractical during the energy ramp. We present an optics measurement method based on adiabatic simultaneous 3-dimensional beam excitation, which is more time-efficient and well fitted for the energy ramp. This method was successfully demonstrated in the LHC utilising AC-dipoles in combination either with a slow RF-frequency modulation or a driven RF-phase modulation close to the synchrotron frequency. Faster longitudinal oscillations improve the accuracy of optics parameters inferred from the synchro-betatron sidebands. This paper reports on the experimental demonstration of optics measurements based on 3D driven beam excitations and the plans for LHC Run 3.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA07

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paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 11 August 2021

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THXB04

Non-Invasive Dispersion Function Measurement during Light Source Operations

operation, lattice, synchrotron, storage-ring

3720

B. Podobedov, Y. Hidaka
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.
We implemented a completely parasitic measurement of lattice dispersion functions in both horizontal and vertical planes, which is fully compatible with light source user operations. The measurement is performed by applying principal component analysis and adaptive filtering to very small residual orbit noise components introduced by the RF system and detected in the beam orbit data, sampled at 10 kHz. No changes in RF frequency are required. The measurement, performed once a minute, was shown to be robust and immune to changes in the beam current, residual orbit noise amplitude and frequency content as well as other factors. At low current it was shown to provide similar accuracy to the traditional method (which shifts the 500 MHz RF frequency by ±500 Hz). In this paper we will explain our measurement technique and present typical dispersion function stability achieved during NSLS-II operations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXB04

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paper received ※ 26 June 2021 paper accepted ※ 13 July 2021 issue date ※ 23 August 2021

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THPAB003

Application of Generalized Gaussian Distribution in the Processing the Wire Scanner Data

hadron, linac, background, electron

3759

H. Geng, C. Meng, F. Yan, Y. Zhang, Y.L. Zhao
IHEP, Beijing, People’s Republic of China

Wire scanners are widely used for measuring beam emittance in both electron and hadron accelerators. Gaussian fitting is the most commonly used method in processing the wire scanner data. But in hadron machines, beams are normally not gaussian distribution due to the action of nonlinear forces such as space charge effect. Under these circumstances, there would be big deviations if the wire scanner data was still fitted with gaussian distributions. This paper introduces generalized Gaussian distribution in the processing the wire scanner data measured in the ADS injector-I. The results using different fitting method will be compared.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB003

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paper received ※ 14 May 2021 paper accepted ※ 18 June 2021 issue date ※ 30 August 2021

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THPAB012

The Magnetic Compensation Scheme of the FCC-ee Detectors

solenoid, detector, quadrupole, electron

3773

M. Koratzinos, K. Oide
CERN, Meyrin, Switzerland

A crucial part of the design of an FCC-ee detector is the minimisation of the disruption of the beam due to the presence of a large and powerful detector magnet. Indeed, the emittance blow-up of the few meters around the interaction point (IP) at lower energies is comparable to the emittance introduced by the rest of the 100 km ring. Vertical emittance is the single most important factor in achieving high performance (luminosity, in this case) in a modern e⁺ e⁻ storage ring such as the FCC-ee. The design adopted is the simplest possible arrangement that can nevertheless deliver high performance: two additional coils per IP side. The performance achieved is such that vertical emittance blow-up will not be a limiting performance factor even in the case of a ring with four experiments, and even in the most demanding energy regime, that of the Z running (about 45 GeV beam energy).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB012

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paper received ※ 10 May 2021 paper accepted ※ 28 July 2021 issue date ※ 30 August 2021

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THPAB017

The International Muon Collider Collaboration

collider, luminosity, target, radiation

3792

D. Schulte
CERN, Meyrin, Switzerland

A muon collider offers a unique opportunity for high-energy, high-luminosity lepton collisions and could push the frontiers of particle physics by providing excellent discovery reach with excellent precision. A scheme has been developed by the MAP collaboration. The updated European Strategy for Particle Physics recommended the development of an Accelerator R&D Roadmap for Europe and CERN Council has charged the LDG to develop it. LDG has initiated panels to provide input including one on the use of muon beams, in particular in view of a high-energy, high luminosity muon collider. A new international collaboration, is forming to develop a muon collider design and address the associated challenges, which are mainly due to the limited muon lifetime. The focus is on two energy ranges, around 3 TeV and above 10 TeV. Ambitious magnets, RF systems, targets and shielding are key for the design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB017

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 11 August 2021

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THPAB060

Dispersion Controlled Temporal Shaping of Photoinjector Laser Pulses for Electron Emittance Reduction in X-Ray Free Electron Lasers

laser, electron, simulation, bunching

3886

R.A. Lemons, S. Carbajo, J.P. Duris, A. Marinelli, N.R. Neveu
SLAC, Menlo Park, California, USA
C.G. Durfee
Colorado School of Mines, Golden, USA

Funding: Office of Science DE-SC0014664
Temporal shaping of photocathode excitation laser pulses is a long-sought-after challenge to tailor the phase-space of electrons. The temporal profile of lasers, typically up-converted from infrared to ultraviolet, have significant impact on the distribution and time-evolution of the collective electron bunches. Towards this end, we present a method combining efficient nonlinear up-conversion with simultaneous and adaptable temporal profile shaping through dispersion-controlled sum-frequency generation* resulting in temporal profiles with sharp rise-fall times and flat top profiles. Using the LCLS-II photoinjector as a case study, we demonstrate a reduction in generated electron transverse emittance by upwards of 30% over conventionally implemented temporal profiles. Additionally, we discuss the ongoing experimental implementation of this method and preliminary results.
* R. Lemons, et al. arXiv:2012.00957 [physics.optics] (2020)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB060

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paper received ※ 17 May 2021 paper accepted ※ 08 July 2021 issue date ※ 26 August 2021

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THPAB064

LUMOS: A Visible Diagnostic Beamline for the Solaris Storage Ring

diagnostics, electron, synchrotron, storage-ring

3901

R. Panaś, A. Curcio, A.I. Wawrzyniak
NSRC SOLARIS, Kraków, Poland

LUMOS is a diagnostic beamline which operates in the visible region. It was installed in the Solaris storage ring during summer 2019. The first light was observed at the beginning of December 2019. During 2020 the beamline was commissioned and equipped with a streak camera setup. Currently, LUMOS allows to analyze far-field and near field images of synchrotron light for transverse beam profile measurements. Moreover, using the streak camera setup, it is also possible to investigate the bunch length, the filling pattern and the longitudinal beam profile changes with respect to the different condition (ramping, 3rd harmonic cavities tuning, etc.). During the presentation the optical setup to be presented along with the measurements conducted with it.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB064

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paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 01 September 2021

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THPAB073

Study of Seven-Bend-Achromat Lattice Option for Half

lattice, storage-ring, octupole, sextupole

3926

J.H. Xu, Z.H. Bai, Z.L. Ren, J.J. Tan, P.H. Yang
USTC/NSRL, Hefei, Anhui, People’s Republic of China
Q. Zhang
INEST, Hefei, People’s Republic of China

A seven-bend-achromat (7BA) storage ring lattice design for Hefei Advanced Light Facility (HALF) with a beam energy of 2.2 GeV and a circumference of 388.8 m is presented. The 7BA lattice is designed with the combined function bends and reverse bends which has a natural emittance of about 67 pm·rad. Two lattice candidates with different tunes have been selected. One lattice has better nonlinear dynamic performance for off-axis injection. The other lattice provides lower beta functions at the center of straight sections. The results of these studies are discussed in this paper.

Poster THPAB073 [1.146 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB073

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paper received ※ 15 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021

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THPAB074

ESRF-EBS: Implementation, Performance and Restart of User Operation

SRF, MMI, operation, storage-ring

3929

J.-L. Revol, P. Berkvens, J.-F. Bouteille, N. Carmignani, L.R. Carver, J.M. Chaize, J. Chavanne, F. Ewald, A. Franchi, L. Hardy, J. Jacob, L. Jolly, G. Le Bec, I. Leconte, S.M. Liuzzo, D. Martin, J. Pasquaud, T.P. Perron, Q. Qin, P. Raimondi, B. Roche, K.B. Scheidt, R. Versteegen, S.M. White
ESRF, Grenoble, France

The European Synchrotron Radiation Facility - Extremely Brilliant Source (ESRF-EBS) is a facility upgrade allowing its scientific users to take advantage of the first high-energy 4th generation light source. In December 2018, after 30 years of operation, the beam stopped for a 12-month shutdown to dismantle the old storage ring and to install the new X-ray source. In December 2019, the first beam was stored and accumulated in the storage ring, allowing the vacuum conditioning and tuning to be started. The beam was delivered to beamlines in March 2020 for their commissioning. On 25 August, the user programme was restarted with beam parameters very close to nominal values. In this report, the milestones and key aspects of the return to user-mode operation are presented and discussed.

Poster THPAB074 [2.864 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB074

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 01 September 2021

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THPAB089

Lattice Design for a Future Plan of UVSOR Synchrotron

dynamic-aperture, optics, lattice, quadrupole

3970

E. Salehi, M. Katoh
UVSOR, Okazaki, Japan
M. Katoh
HSRC, Higashi-Hiroshima, Japan

UVSOR is a 750 MeV synchrotron light source with a moderately small emittance of about 17nm. We surveyed the periodic solutions by drawing a tie diagram and mapped the emittance and the dynamic aperture on the tune diagram. The aim of this work is to search for a possible low emittance solution without a major change of the lattice. Although, we could not find a solution which has a drastically small emittance, we have found a few solutions which has a significantly smaller emittance than present value. They may be useful for some special low emittance operation modes dedicated to developments on new light sources technologies and their applications.

Poster THPAB089 [1.592 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB089

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 16 August 2021

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THPAB090

Progress with the Diamond-II Storage Ring Lattice

storage-ring, lattice, sextupole, injection

3973

H. Ghasem, I.P.S. Martin, B. Singh
DLS, Oxfordshire, United Kingdom

Building on the CDR proposal for the Diamond-II storage ring, a number of changes have been implemented to improve the performance of the lattice. Firstly, anti-bend magnets have been utilized to provide additional control over the dispersion function, and an improved symmetrization in the phase advance between the sextupoles was found to be beneficial for the dynamic aperture. Furthermore, the longitudinal variable bends have been tailored to reduce the emittance and have had transverse gradient added to improve the optics control in the mid-straights. In the absence of IDs, the current design provides 161 pm electron beam emittance, reducing to 139 pm once all effects are taken into account. The dynamic aperture is large enough to support an off-axis injection scheme using a nonlinear kicker and has a lifetime greater than 4 h. In this paper, the main parameters and magnet specifications for the Diamond-II lattice are provided. The related linear and non-linear beam dynamics issues are discussed, along with the impact of IDs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB090

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paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 26 August 2021

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THPAB106

Optimization of a High Bunch Charge ERL Injection Merger for PERLE

linac, space-charge, booster, cavity

3983

B. Hounsell, M. Klein, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
S.A. Bogacz
JLab, Newport News, Virginia, USA
C. Bruni, B. Hounsell, W. Kaabi
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
B. Hounsell, B.L. Militsyn, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Delivery of high charge electron bunches into the main loop of an ERL (energy recovery linac) while preserving the emittance is challenging. This is because at the typical injection momentum, space charge forces still have a significant effect on the beam dynamics. In this work we consider the design of the merger for PERLE, an ERL test facility to be based at IJCLab in France. Previous simulations have shown that the baseline DC gun based injector can achieve the required emittance at the booster linac exit. The quality of the 500 pC bunches must then be preserved with space charge through the merger at total beam energy of 7 MeV keeping the emittance below 6 mm mrad. The beam dynamics in the merger were simulated using the code OPAL and optimised using a genetic algorithm. Three possible merger schemes were investigated. The goal of the optimisation was to minimise the emittance growth while also achieving the required Twiss parameters to match onto the spreader at the main linac exit. A three dipole solution is then examined in more detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB106

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paper received ※ 19 May 2021 paper accepted ※ 16 July 2021 issue date ※ 12 August 2021

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THPAB119

Many-Objective Beam Dynamics Optimization for High-Repetition-Rate XFEL Photoinjector

FEL, electron, gun, laser

3991

Z.H. Zhu, J.W. Yan
SINAP, Shanghai, People’s Republic of China
D. Gu
SARI-CAS, Pudong, Shanghai, People’s Republic of China
Q. Gu
Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China

SHINE, as the first hard x-ray free-electron-laser (FEL) facility in China, is design to provide high-brightness FEL lasing under high-repetition-rate operation. In order to drive x-ray FEL pulses with high qualities, the photoinjector section is deployed to provide the specified electron beam with low transverse emittance and high brightness. Normally the multi-objective optimization algorithm is employed in the injector beam dynamics design. In this paper, the many-objective optimization algorithm NSGA-III is introduced to the injector physical design for optimizing the 4 detailed beam quality properties using 17 variables for the first time. The results of the optimization are presented and the correlations are analyzed. This approach can provide guidance for further physical research as well as improve the beam dynamics optimization efficiency.

Poster THPAB119 [0.936 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB119

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paper received ※ 17 May 2021 paper accepted ※ 07 July 2021 issue date ※ 22 August 2021

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THPAB121

Plasma Muon Beam Cooling for HEP

plasma, focusing, cavity, simulation

3999

M.A. Cummings, R.J. Abrams, R.P. Johnson, S.A. Kahn, T.J. Roberts
Muons, Inc, Illinois, USA
V.S. Morozov, A.V. Sy
JLab, Newport News, Virginia, USA
K. Yonehara
Fermilab, Batavia, Illinois, USA

Ionization cooling has the potential to shrink the phase space of a muon beam by a factor of 10⁶ within the muons’ short lifetime (2.2 µs) because the collision frequency in a cooling medium is extremely high compared to conventional beam cooling methods. It has been realized that ionization cooling inherently produces a plasma of free electrons inside the absorber material, and this plasma can have an important effect on the muon beam. In particular, under the right circumstances, it can both improve the rate of cooling and reduce the equilibrium emittance of the beam. This has the potential to improve the performance of muon facilities based on muon cooling; in particular a future muon collider. We describe how this project will integrate Plasma muon beam cooling into both the basic Helical Cooling Channel (HCC) and extreme Parametric-resonance Ionization Cooling (PIC) techniques. This potentially whole new approach to muon cooling has exciting prospects for significantly reduced muon beam emittance.

Poster THPAB121 [1.214 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB121

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021

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THPAB129

Beam Dynamics Simulations in a High-Gradient X-Band Photoinjector

gun, cathode, electron, linac

4013

W.H. Tan, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
G. Chen, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
G. Chen
IIT, Chicago, Illinois, USA
G. Ha, C.-J. Jing
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid Beamlabs, Bolingbrook, USA

A high-gradient X-band (11.7-GHz) photoinjector was recently developed by Euclid Techlabs and is in its commissioning phase at the Argonne Wakefield Accelerator (AWA). This contribution discuss the beam-dynamics modeling of the photoinjector system comprising an RF gun and linac section. We especially discuss beam-dynamics optimization of setup for an integrated proof-of-principle experiments. We also discuss the use of such a photoinjector as a witness-bunch source for a future high-gradient collinear-wakefield accelerator experiments at the AWA.
* S. V. Kuzikov, et al. these proceedings.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB129

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paper received ※ 20 May 2021 paper accepted ※ 14 July 2021 issue date ※ 31 August 2021

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THPAB140

Modelling Seeded Self Modulation of Long Elliptical Bunches in Plasma

plasma, wakefield, simulation, proton

4030

A. Perera, O. Apsimon, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J. Resta-López
IFIC, Valencia, Spain

Funding: This work was supported by STFC Centre for Doctoral Training in Data-Intensive Science (LIV. DAT) under grant ST/P006752/1 and the STFC Scientific Computing Department’s SCARF cluster.
The stability of particle bunches undergoing seeded self-modulation (SSM) over tens or hundreds of meters is crucial to the generation of GV/m wakefields that can accelerate electron beams as proposed for use in several high energy plasma-based linear colliders. Here, 3D particle-in-cell simulations using QuickPIC are compared to an analytical model of seeded self-modulation (SSM) of elliptical beam envelopes using linear wakefield theory. It is found that there is quantitative agreement between simulations and analytical predictions for the envelope in the early growth of the SSM. A scaling law is derived for the reduction of the maximum overall modulation growth rate with aspect ratio and is found to match well with simulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB140

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paper received ※ 19 May 2021 paper accepted ※ 22 July 2021 issue date ※ 31 August 2021

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THPAB142

Optical and Surface Characterization of Alkali-Antimonide Photocathodes

cathode, electron, photon, vacuum

4037

P. Saha, O. Chubenko, G.S. Gevorkyan, A.H. Kachwala, S.S. Karkare, C.J. Knill
Arizona State University, Tempe, USA
E.J. Montgomery, S. Poddar
Euclid Beamlabs, Bolingbrook, USA
H.A. Padmore
LBNL, Berkeley, California, USA

Alkali-antimonides, characterized by high quantum efficiency and low mean transverse energy in visible light, are excellent electron sources to drive x-ray free electron lasers, electron cooling and ultrafast electron diffraction applications etc. Existing studies of alkali-antimonides have focused on quantum efficiency and emittance, but information is lacking on the fundamental aspects of the electronic structure, such as the energy gap of the semiconductor and the density of defects as well as the overall nano-structure of the materials. We are, therefore, conducting photoconductivity measurements to measure fundamental semiconductor properties as well as using atomic force microscope (AFM) and kelvin probe force microscope (KPFM) to measure the nanostructure variations in structure and surface potential.

Poster THPAB142 [1.211 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB142

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paper received ※ 16 May 2021 paper accepted ※ 14 July 2021 issue date ※ 13 August 2021

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THPAB165

5 MW Beam Power in the ESSnuSB Accumulator: A Way to Manage Foil Stripping Injection at 14 Hz Linac Pulse Rate

linac, injection, proton, space-charge

4072

H. Schönauer
CERN, Geneva, Switzerland
Y. Zou
Uppsala University, Uppsala, Sweden

Funding: This work is supported by the European Union’s Horizon 2020 research and innovation program under grant agreement No 777419.
In the past, the scenario for foil stripping consisted of splitting a linac pulse into 4 rings, or 3 or 4 intermediate pulses, and one ring. At present, the scenario, in view of laser stripping, consists of one ring, one pulse, split into four batches. Conventional stripping geometry would lead to foil evaporation under this beam load. One way out appears to be replacing the standard corner foil by a single-edge foil rotated to about 45deg. The tilted foil allows moving the injection point together with the painting bumps along the foil edge, distributing the deposited beam power over a larger foil area. Simulation results obtained with the same tools as in the past scenarios are presented. They show peak foil temperatures, which compare with the best results obtained from the past scenarios.

Poster THPAB165 [2.205 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB165

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paper received ※ 11 May 2021 paper accepted ※ 21 June 2021 issue date ※ 18 August 2021

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THPAB169

A Mechanism for Emittance Growth Based on Non-Linear Islands in LHC

octupole, ECR, operation, resonance

4082

E.H. Maclean, M. Giovannozzi, T.H.B. Persson, R. Tomás García
CERN, Geneva, Switzerland

Landau octupoles are used in the LHC to prevent coherent instabilities of the circulating beam. The reduction of their strength occurring during the energy ramp can transport particles in nonlinear islands to larger amplitude. This has the potential to lead to emittance growth and to beam-losses. Beam-based studies and simulations of emittance growth during Landau octupole ramps performed in the LHC are presented to explore this mechanism in more detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB169

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paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 14 August 2021

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THPAB172

Bunch Luminosity Variations in LHC Run 2

luminosity, injection, experiment, operation

4094

I. Efthymiopoulos, S.D. Fartoukh, G. Iadarola, N. Karastathis, S. Papadopoulou, Y. Papaphilippou
CERN, Geneva, Switzerland

The LHC is designed to collide intense bunches of protons with tightly defined conditions, aimed to maximize the delivered recorded integrated luminosity to the experiments. One of these conditions is the maximum level of bunch-to-bunch fluctuation in the luminosity, in particular when levelling at maximum acceptable event rate at the experiments. Analysis results of the bunch-to-bunch luminosity variations in LHC Run 2 are presented here. In particular, the observed correlations with the LHC filling pattern that can enhance the effects introducing bunch-dependent losses or emittance blow-up from injection to collisions are discussed. In Run 2 conditions, bunch-by-bunch luminosity fluctuations reached 10% at the start of collisions and gradually increased with time, without affecting the experiments as the luminosity was not levelled. Projections for Run 3 and HL-LHC operation are discussed along with envisaged mitigation measures.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB172

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paper received ※ 18 May 2021 paper accepted ※ 19 July 2021 issue date ※ 23 August 2021

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THPAB174

T-BMT Spin Resonance Tracker Code for He3 with Six Snakes

resonance, polarization, HOM, betatron

4101

V.H. Ranjbar, H. Huang, Y. Luo, F. Méot, V. Ptitsyn
BNL, Upton, New York, USA
G.H. Hoffstaetter, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
F. Lin, V.S. Morozov
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy .
Polarization lifetime for He3 using two and six snakes are studied using the T-BMT Spin Resonance Tracker code. This code integrates a reduced spinor form of the T-BMT equation including only several spin resonances and the kinematics of synchrotron motion. It was previously benchmarked against RHIC polarization lifetime under the two snake system *.
* Phys. Rev.Accel. Beams 22 (2019) 9, 091001

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB174

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paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 28 August 2021

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THPAB175

nuSTORM Accelerator Challenges and Opportunities

collider, storage-ring, target, experiment

4104

C.T. Rogers, J.-B. Lagrange
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
N. Gall
CERN, Meyrin, Switzerland
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The nuSTORM facility uses a stored muon beam to generate a neutrino source. Muons are captured and stored in a storage ring using stochastic injection. The facility will aim to measure neutrino-nucleus scattering cross-sections with uniquely well-characterized neutrino beams; to facilitate the search for sterile neutrino and other Beyond Standard Model processes with exquisite sensitivity, and to provide a muon source that makes an excellent technology test-bed required for the development of muon beams capable of serving as a multi-TeV collider. In this paper, we describe the latest status of the development of nuSTORM, the R&D needs, and the potential for nuSTORM as a Muon Collider test facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB175

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paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 31 August 2021

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THPAB180

Simulation of 4D Emittance Measurement at the Spallation Neutron Source

quadrupole, simulation, space-charge, optics

4119

A.M. Hoover
UTK, Knoxville, Tennessee, USA
N.J. Evans
ORNL RAD, Oak Ridge, Tennessee, USA

Similar to the KV distribution, the Danilov distribution has an elliptical shape and uniform density in the transverse plane and maintains these properties under any linear transport. Efforts are underway at the Spallation Neutron Source (SNS) to paint a Danilov distribution in the accumulator ring. After the beam has been painted, the level to which it approximates an ideal Danilov distribution must be quantified. One way to do this is to measure the four-dimensional emittance, which is ideally zero due to linear relationships between the phase space variables. To measure this emittance, we will utilize a standard method of reconstructing the covariance matrix using various optics settings in conjunction with beam profile measurements. We present the results of preliminary simulations which aim to optimize this measurement scheme for the SNS Ring to Target Beam Transport (RTBT) line.

Poster THPAB180 [2.525 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB180

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 25 August 2021

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THPAB183

New Longitudinal Beam Production Methods in the CERN Proton Synchrotron Booster

space-charge, proton, resonance, cavity

4130

S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, E. Renner
CERN, Meyrin, Switzerland
E. Renner
TU Vienna, Wien, Austria

As part of the LHC Injectors Upgrade (LIU) project, significant improvements were made to the CERN Proton Synchrotron Booster (PSB) during the 2019/2020 long shutdown, including a new Finemet-based wideband RF system, renovated longitudinal beam control, and a new magnetic cycle. To meet the requirements of the diverse experimental program, the PSB provides beams with intensities spanning three orders of magnitude and a large range of longitudinal emittances. To maximize the brightness, in particular for the LHC beams, the voltages at low energy are designed to reduce the impact of transverse space charge using a second RF harmonic in bunch lengthening mode. At high energies, the risk of longitudinal microwave instability is avoided by optimizing the longitudinal distribution to raise the instability threshold. RF phase noise is applied to provide controlled longitudinal emittance blow-up and to shape the longitudinal distribution. This paper discusses the design of the RF functions used to meet the beam specifications, whilst ensuring longitudinal stability.

Poster THPAB183 [6.692 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB183

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paper received ※ 18 May 2021 paper accepted ※ 22 July 2021 issue date ※ 20 August 2021

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THPAB185

Solution to Beam Transmission Decline in the CSNS Linac Operation Using Measurements and Simulations

rfq, DTL, linac, operation

4134

J. Peng, M.T. Li, X.H. Lu, X.B. Luo
IHEP CSNS, Guangdong Province, People’s Republic of China
Y.W. An, S. Fu, L. Huang, M.Y. Huang, Y. Li, Z.P. Li, S. Wang, S.Y. Xu, Y. Yuan
IHEP, Beijing, People’s Republic of China

The CSNS linac operation at its design average power currently. However, the beam transmission is declining and the beam loss is increasing during the operation. With simulations and experiments, we found there is a long longitudinal tail exist in the beam bunch output from the RFQ. And this tail caused the beam loss in the following linac. After inhibition of the longitudinal tail in the beam bunch, the beam transmission in operation can keep stable.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB185

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 02 September 2021

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THPAB202

Problem and Solution with the Longitudinal Tracking of the ORBIT Code

simulation, acceleration, synchrotron, space-charge

4176

L.H. Zhang, J.Y. Tang
IHEP, Beijing, People’s Republic of China
Y.K. Chen
IHEP CSNS, Guangdong Province, People’s Republic of China
L.H. Zhang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

The ORBIT code has been widely used for beam dynamics simulations including injection and acceleration in high-intensity hadron synchrotrons. When the ORBIT’s 1D longitudinal tracking was employed for the acceleration process in CSNS/RCS, the longitudinal emittance in eV-s was found decreasing substantially during acceleration, though the adiabatic condition is still met during this process. This is against the Liouville theorem that predicts the preservation of the emittance during acceleration. The recent machine study in the accelerator and the simulations with a self-made code demonstrate that the longitudinal emittance is almost invariant, which further indicates that the ORBIT longitudinal tracking might be incorrect. A detailed check-over in the ORBIT code source finds that the longitudinal finite difference equation used in the code is erroneous when applied to an acceleration process. The new code format PyORBIT has the same problem. After the small secondary factor is included in the code, ORBIT can produce results keeping the longitudinal emittance invariant. This paper presents some details about the study.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB202

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paper received ※ 14 May 2021 paper accepted ※ 01 July 2021 issue date ※ 21 August 2021

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THPAB206

Validating pyORBIT for Modeling Beam Dynamics in the IOTA Ring

space-charge, proton, octupole, dynamic-aperture

4190

R. Li
UW-Madison/PD, Madison, Wisconsin, USA
J.-F. Ostiguy, T. Sen
Fermilab, Batavia, Illinois, USA

Funding: Supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The Integrable Optics Test Accelerator (IOTA) ring is a new Fermilab facility dedicated to beam physics experiments, currently operating with 150 MeV electrons. Space charge effects are expected to be significant when it operates with 2.5 MeV protons. In this contribution, we present results of a suite of validation tests of PyORBIT, a PICstyle space charge code. Single particle dynamics of quasiintegrable optics using an octupole string in IOTA is compared with MADX, and shown to be in good agreement. Requirements for the convergence of space charge computations are systematically established and when possible, tests involving space charge are compared with theoretical predictions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB206

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paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 12 August 2021

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THPAB219

Beam Dynamics in Coherent Electron Cooling Accelerator

electron, simulation, linac, cavity

4216

Y.C. Jing, V. Litvinenko, I. Petrushina, I. Pinayev, K. Shih, Y.H. Wu
BNL, Upton, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
I. Petrushina, Y.H. Wu
SUNY SB, Stony Brook, New York, USA
K. Shih
SBU, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron Cooling (CeC) has the potential to substantially reduce the cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. Recent development in CeC cooling theory requires the accelerator to deliver high-quality electron bunches with low beam noise. In this paper, we present our design of the CeC accelerator to achieve the electron beam requirements and compare our findings with the experimental observations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB219

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paper received ※ 27 May 2021 paper accepted ※ 27 July 2021 issue date ※ 11 August 2021

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THPAB220

Multibunch Studies for LCLS-II High Energy Upgrade

cavity, dipole, linac, HOM

4219

R.J. England, K.L.F. Bane, Z. Li, T.O. Raubenheimer, M.D. Woodley
SLAC, Menlo Park, California, USA
M. Borland
ANL, Lemont, Illinois, USA
A. Lunin
Fermilab, Batavia, Illinois, USA

Funding: The work is supported in part by DOE Contract No. DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) X-ray free-electron laser at SLAC is being upgraded to LCLS-II with a superconducting linac and 1 MHz bunch repetition rate. The proposed high-energy upgrade (LCLS-II-HE) will increase the beam energy from 4 to 8 GeV, extending the reach of accessible X-ray photon energies. With the increased repetition rate and longer linac of LCLS-II-HE, multi-bunch effects are of greater concern. We use recently introduced capabilities in the beam transport code ELEGANT to study dipole and monopole beam breakup effects for LCLS-II HE beam parameters. The results indicate that resonant dipole kicks have steady-state settle times on the order of 500 bunches or less and appear manageable. We also consider a statistical variation of the cavity frequencies and transverse offsets of cavities and quadrupoles. Resonant emittance growth driven by monopole kicks is found to be disrupted by frequency variation between cavities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB220

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paper received ※ 19 May 2021 paper accepted ※ 15 July 2021 issue date ※ 21 August 2021

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THPAB240

Combined Effect of IBS and Impedance on the Longitudinal Beam Dynamics

experiment, simulation, lattice, wakefield

4274

A. Blednykh
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
B. Bacha, G. Bassi, T.V. Shaftan, V.V. Smaluk
BNL, Upton, New York, USA
M. Borland, R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The horizontal/vertical emittances, the bunch length, and the energy spread increase have been studied in the NSLS-II as a function of a single bunch current. The monotonic growth of the horizontal emittance dependence and the energy spread dependence on the single bunch current below the microwave instability threshold can be explained by the Intrabeam Scattering Effect (IBS). The IBS effect results in an increase in the bunch length and the microwave instability thresholds. It was observed experimentally by varying the vertical emittance. To compare with experimental data, particle tracking simulations have been performed with the ELEGANT code including both IBS and the total longitudinal wakefield calculated from the 3D electromagnetic code GdfidL. The same particle tracking simulations have also been applied for the APS-U project, where IBS is predicted to produce only a marginal effect.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB240

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paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021

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THPAB258

Status of Time-Domain Simulation for the Fast Orbit Feedback System at the HEPS

simulation, feedback, vacuum, power-supply

4311

Y. Wei, Z. Duan, X.Y. Huang, Y. Jiao
IHEP, Beijing, People’s Republic of China

High Energy Photon Source (HEPS) is a complex designed at ultra-low emittance. A fast orbit feedback system is proposed to meet the requirement of beam orbit stability at the sub-micron level. In this paper, we present our work on setting up an orbit feedback process combined with noise model, system modeling, and particle tracking in the time domain. RF phase parameter is adjusted together with fast correctors to mitigate the orbit fluctuation due to energy vibration. The preliminary results are shown here. By the following optimization, we hope to provide an effective tool to specify and configure the FOFB system with the simulation.

Poster THPAB258 [1.334 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB258

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 31 August 2021

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THPAB276

X-Ray Double Slit Interferometer Progress at CLS

synchrotron, simulation, storage-ring, photon

4349

N.A. Simonson, Y. Yousefi Sigari
University of Saskatchewan, Saskatoon, Canada
M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada

The Canadian Light Source (CLS) is a 3rd generation synchrotron that is used to produce extremely bright synchrotron light that can be used for research. The light at the CLS is produced by an electron storage ring that has an emittance of 20 nm. A 4th generation synchrotron (CLS2) is planned which will reduce the emittance to less than 1 nm and thus reduce the transverse beam size significantly, making it very challenging to measure. A double slit interferometer can be used to measure small transverse beam sizes, as first described by Mitsuhashi. An x-ray double slit interferometer will be designed and tested at the current CLS with the goal of using this setup at CLS2.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB276

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paper received ※ 20 May 2021 paper accepted ※ 23 July 2021 issue date ※ 01 September 2021

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THPAB344

Magneto-Optical Trap Cathode for High Brightness Applications

electron, laser, gun, cathode

4466

V.S. Yu, C.E. Hansel, G.E. Lawler, M. Mills, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
J.I. Mann
PBPL, Los Angeles, USA

Funding: This work was performed with support of the US Department of Energy under Contract No. DE-SC0020409 and the National Science Foundation under Grant No. PHY-1549132
Electron bunches extracted from magneto-optical traps (MOTs) via femtosecond photo-ionization and electrostatic acceleration can have significantly lower transverse emittance than emissions from traditional metal cathodes. Such MOT cathodes, however, have two drawbacks: the need for multiple trapping lasers and the limit to ~MV/m fields. Designs exist for MOTs which only require one trapping laser. Our RF simulations in High-Frequency Structure Simulator (HFSS) indicate that the cone MOT is the only one compatible with high gradient RF cavities. We present the combination of the two, an RF cavity with a cone-MOT as part of its geometry. It only requires one trapping laser and can use much higher fields. The geometry of the chamber is compatible with a wide range of MOT species, which allows the search for one which is compatible with copper cavities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB344

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paper received ※ 19 May 2021 paper accepted ※ 29 July 2021 issue date ※ 12 August 2021

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FRXB05

Muon Ionization Cooling Experiment: Results & Prospects

experiment, solenoid, collider, proton

4528

C.T. Rogers
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

A high-energy muon collider could be the most powerful and cost-effective collider approach in the multi-TeV regime, and a neutrino source based on decay of an intense muon beam would be ideal for measurement of neutrino oscillation parameters. Muon beams may be created through the decay of pions produced in the interaction of a proton beam with a target. The muons are subsequently accelerated and injected into a storage ring where they decay producing a beam of neutrinos, or collide with counter-rotating antimuons. Cooling of the muon beam would enable more muons to be accelerated resulting in a more intense neutrino source and higher collider luminosity. Ionization cooling is the novel technique by which it is proposed to cool the beam. The Muon Ionization Cooling Experiment collaboration constructed a section of an ionization cooling channel and used it to provide the first demonstration of ionization cooling. Here the observation of ionization cooling is described. The cooling performance is studied for a variety of beam and magnetic field configurations. The outlook for muon ionization cooling demonstrations is discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB05

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paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 23 August 2021

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FRXB07

Injector Optimization for the IR-FEL Operation at the Compact ERL at KEK

FEL, gun, operation, laser

4531

O.A. Tanaka, N. Higashi, T. Miyajima
KEK, Ibaraki, Japan

Funding: Work supported by NEDO project "Development of advanced laser processing with intelligence based high-brightness and high-efficiency laser technologies (TACMI project)".
The Compact Energy Recovery Linac (cERL) at KEK is a test accelerator to develop ERL technologies and to operate with a high average beam current and a high beam quality. cERL consists of a photoinjector, a main linac for energy recovery, a recirculation loop and a beam dump. A recent upgrade of the cERL to the middle Infrared Free Electron Laser (IR-FEL) imposed new conditions to maintain beam parameters. Therefore, the injector should be optimized to meet the following requirements at the exit of the main linac. The rms bunch length should be 2 ps, the rms longitudinal emittance should be kept the least, and simultaneously the rms transverse emittance should be kept less than 3 c mm mrad. In this work we describe the strategy and results of the injector optimization to achieve the better performance of the cERL-FEL.

Slides FRXB07 [3.450 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB07

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paper received ※ 19 May 2021 paper accepted ※ 22 July 2021 issue date ※ 14 August 2021

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FRXC04

Time-Resolved H⁻ Beam Emittance Measurement at the SNS Linac Using a Laser Comb

laser, neutron, diagnostics, beam-diagnostic

4545

Y. Liu, A.V. Aleksandrov, C.D. Long
ORNL, Oak Ridge, Tennessee, USA

Funding: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE).
We proposed and demonstrated a novel technique to measure time-resolved transverse emittances of the hydrogen ion (H⁻) beam in a 1-GeV high-power accelerator. The measurement is performed in a non-intrusive manner by using laser comb - laser pulses with controllable multi-layer temporal structure generated from a fiber-based master laser oscillator and diode-pumped solid-state laser amplifiers. The technique has been applied to the transverse emittance measurement of 1-GeV H⁻ beam at the Spallation Neutron Source (SNS) high energy beam transport (HEBT). More than 20 time-resolved emittances have been simultaneously measured within a macro-pulse, a single mini-pulse, or a single bunch of the 1.4-MW neutron production H⁻ beam from one measurement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXC04

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paper received ※ 18 May 2021 paper accepted ※ 08 July 2021 issue date ※ 20 August 2021

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