IPAC2021 - List of Keywords (dipole)

Paper	Title	Other Keywords	Page
MOPAB001	Power Deposition in Superconducting Dispersion Suppressor Magnets Downstream of the Betatron Cleaning Insertion for HL-LHC	proton, collimation, simulation, operation	37
	A. Waets, C. Bahamonde Castro, E. Belli, R. Bruce, N. Fuster-Martínez, A. Lechner, A. Mereghetti, S. Redaelli, M. Sabaté-Gilarte, E. Skordis CERN, Meyrin, Switzerland
	Funding: Research supported by the HL-LHC project The power deposited in dispersion suppressor magnets downstream of the Large Hadron Collider (LHC) betatron cleaning insertion is governed by off-momentum particles scattered out of the primary collimators. In order to mitigate the risk of magnet quenches during periods of short beam lifetime in future High-Luminosity (HL-LHC) operation, new dispersion suppressor (DS) collimators are considered for installation (one per beam). In this paper, we present FLUKA simulations for both protons and Pb ions at 7 TeV, predicting the power deposition in the DS magnets, including the new higher-field dipoles 11T which are needed to integrate the collimator in the cold region next to the cleaning insertion. The simulated power deposition levels for the adopted HL-LHC collimator configuration and settings are used to assess the quench margin by comparison with the present estimated quench levels.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB001
About •	paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 16 August 2021
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MOPAB014	First High Spin-Flip Efficiency for High Energy Polarized Protons	polarization, resonance, proton, experiment	84
	H. Huang, J. Kewisch, C. Liu, A. Marusic, W. Meng, F. Méot, P. Oddo, V. Ptitsyn, V.H. Ranjbar, T. Roser 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 order to minimize the systematic errors for the Relativistic Heavy Ion Collider (RHIC) spin physics experiments, flipping the spin of each bunch of protons during the stores is needed. Experiments done with single RF magnet at energies less than 2 GeV have demonstrated a spin-flip efficiency over 99%. At high energy colliders with Siberian snakes, a single magnet spin flipper does not work because of the large spin tune spread and the generation of multiple, overlapping resonances. Over past decade, RHIC spin flipper design has evolved and a sophisticated spin flipper, constructed of nine-dipole magnets, was developed to flip the spin in RHIC. A special optics choice was also used to make the spin tune spread very small. In recent experiment, 97% spin-flip efficiency was measured at both 24 and 255 GeV for the first time. The results show that efficient spin flipping can be achieved at high energies.
	Poster MOPAB014 [0.984 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB014
About •	paper received ※ 16 May 2021 paper accepted ※ 08 June 2021 issue date ※ 20 August 2021
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MOPAB026	RHIC Delayed Abort Experiments	experiment, kicker, injection, quadrupole	126
	M. Valette, D. Bruno, K.A. Drees, K.M. Hartmann, G. Heppner, K. Mernick, C. Mi, J.-L. Mi, R.J. Michnoff, J. Morris, F. Orsatti, E. Rydout, T. Samms, J. Sandberg, V. Schoefer, C. Schultheiss, T.C. Shrey, C. Theisen 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. For RHIC to operate at its top energy (100 GeV/n) while protecting the future sPHENIX detector, spontaneous and asynchronous firing of abort kicker modules (pre-fires) have to be avoided. A new triggering circuit for the abort kickers was implemented with relatively slow mechanical relays in series with the standard fast thyratron tubes. The relays prevents unwanted pre-fires during operation, but comes at the expense of a long latency - about 7 milliseconds - between the removal of beam permit and the actual firing of the abort kickers. Protection considerations of RHIC’s superconducting magnets forbid delaying energy extraction from the main dipoles and quadrupoles for too long after a quench. The beam has thus to circulate in both RHIc rings for a few milliseconds as the current in dipole and quadrupole circuit is being extracted. We present the results of delayed abort experiments conducted in July 2018 with the analysis of fast orbit and tune measurements and discuss the safety implications of this implementation for future RHIC operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB026
About •	paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 23 August 2021
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MOPAB058	Swap-Out Safety Tracking for the Advanced Photon Source Upgrade	photon, simulation, electron, power-supply	249
	M. Borland, J.S. Downey, M.S. Jaski 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 will operate in swap-out mode, which is similar to top-up but involves complete replacement of individual depleted bunches in a single shot. As with top-up, safety is a concern given that this process will take place with beamline shutters open. We describe the methods used to model swap-out safety, including creation and validation of a full ring lattice based on 3D field maps. We also describe a new method of implementing complex, intersecting channels for electron beams and photon beams, as well as a method of easily identifying potentially dangerous stray particles. Numerous potential errors (e.g., magnet shorts) were modeled, giving a reliable indication of performance of proposed stored beam and magnet interlocks.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB058
About •	paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 29 August 2021
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MOPAB059	Tools for Use of Generalized Gradient Expansions in Accelerator Simulations	lattice, simulation, septum, quadrupole	253
	M. Borland, R.R. Lindberg, R. Soliday, A. Xiao 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. A common assumption in simulation of accelerators is that the magnets can be approximated using a hard-edge model, perhaps with some edge effects implemented in an impulse approximation. This is usually a good assumption but ignores details of the longitudinal variation of the magnetic fields, which makes it straightforward to implement symplectic tracking. Use of generalized gradient expansions* provides an alternative approach that can suppress numerical deficiencies that may be present in computed or measured 3D field maps. However, the computation of the expansions is not particularly straightforward. In this note, we describe several recently-developed tools that make this process fairly painless and allow tracking with such expansions in the program ELEGANT*. We show several examples of using the tools for simulations related to the Advanced Photon Source Upgrade. M. Venturini et al., NIM A 427, 387 (1999). ** M. Borland, Advanced Photon Source LS-287, September 2000
	Poster MOPAB059 [4.311 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB059
About •	paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 18 August 2021
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MOPAB062	A Single Dipole Source for Broad-Band Soft Photon Beamlines in Diamond-II	lattice, emittance, 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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MOPAB089	Effect of Different Models of Combined-function Dipoles on the HEPS Parameters	lattice, storage-ring, quadrupole, emittance	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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MOPAB092	Project of Wuhan Photon Source	storage-ring, cavity, injection, linac	346
	H.H. Li, Y. Deng, J.H. He, Y. Nie, L. Tang, J. Wang, Y.X. Zhu IAS, Wuhan City, People’s Republic of China
	Wuhan Photon Source (WHPS) has been designed as a fourth-generation light source, which consists of a low energy storage ring (1.5 GeV), a medium energy storage ring (4.0 GeV), and a linac working as a full energy injector. It has been planned to build the low energy light source first as the Phase I project, and then the medium energy light source after its completion. The low energy storage ring has been optimized with the main design parameters as following: An 8-cell, 500 mA storage ring, with a circumference of 180 m and nature emittance 238.4 pm-rad. Based on hybrid-7BA lattice structure, it reaches the soft X-ray diffraction limit. And at the middle of each cell, a 3.5 T superB magnet is used to extend the photon energy to the hard X-ray region. The swap-out injection is chosen due to the small dynamic aperture and a full energy S-band LINAC will be used as its injector. A 3rd harmonic cavity is designed for bunch lengthening to keep a sufficient lifetime. More details of the WHPS phase I project will be described in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB092
About •	paper received ※ 10 June 2021 paper accepted ※ 23 June 2021 issue date ※ 24 August 2021
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MOPAB127	Construction of an Impedance Model for Diamond-II	impedance, simulation, lattice, cavity	455
	R.T. Fielder, T. Olsson DLS, Oxfordshire, United Kingdom
	Impedance models for accelerators have traditionally been presented in a static form, usually as tables or spreadsheets which must be read manually. As part of the Diamond-II upgrade work, we have developed an impedance model using a lattice structure. This allows more direct integration with simulation codes while keeping important information easily human readable. We present here a description of this implementation method, along with an overview of the Diamond-II impedance model derived from the latest engineering design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB127
About •	paper received ※ 18 May 2021 paper accepted ※ 20 May 2021 issue date ※ 11 August 2021
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MOPAB178	Systematic Effects Limiting the Sensitivity of "Magic Energy" Proton EDM Rings	proton, betatron, pick-up, focusing	602
	C. Carli, M. Haj Tahar CERN, Geneva, Switzerland
	Proposals to measure a possible Electric Dipole Moment (EDM) of protons in an electro-static storage ring are studied by a world-wide community. The machine is operated at the so-called "magic energy" to satisfy the "frozen spin" condition such that, without imperfections and with the well known magnetic moment of the particle, the spin is always oriented parallel to the direction of movement. The effect of a finite EDM is a build-up of a vertical spin component. Any effect, other than a finite EDM, leading as well to a build-up of a vertical spin limits the sensitivity of the experiment. Such "systematic effects" are caused by machine imperfections, such as magnetic fields inside the magnetic shield surrounding the ring, and misalignments of electro-static elements or of the RF cavity. Operation of the machine with counter-rotating beams helps mitigating some of the effects. The most dangerous effects are those, which cannot be disentangled from an EDM by combining measurements from both counter-rotating beams, such as an average residual radial magnetic field penetrating the magnetic shield or a combination of magnetic fields and misalignments of electric elements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB178
About •	paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 20 August 2021
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MOPAB181	Non-Delivery Time Reduction at MedAustron	extraction, proton, synchrotron, MMI	613
	L. Adler, S. Danzinger, F. Farinon, F. Feichtinger, G. Guidoboni, N. Kahn, C. Kurfürst, D.A. Prokopovich, A. Wastl EBG MedAustron, Wr. Neustadt, Austria L.C. Penescu Abstract Landscapes, Montpellier, France
	Funding: Funding by the NÖ WIRTSCHAFTS- UND TOURISMUSFONDS under grant number WST3-F-5033232/001-2020. MedAustron is a cancer treatment center in Austria providing proton and carbon ion beams to three clinical and one non-clinical research beam lines. The slow extraction of particles from the synchrotron follows a third order resonance extraction scheme. Currently, for every change of extraction energy a new spill needs to be generated. Besides the beam-on time of the particle delivery, every spill is also comprised of non-delivery time components e.g. the multiturn injection, acceleration or magnet conditioning. For small tumor target volumes, this non-delivery time is the major contribution to the overall treatment time. A dedicated performance improvement project (supported with a grant from the state of lower Austria) was executed with the goal to reduce these non-delivery times without affecting important clinical beam parameters such as the beam size or penetration depth. The implemented reduction of the non-delivery time >50% could be achieved, resulting in beam-on time reductions for reference treatment plans between 25% (largest proton PTV) and 58% (smallest carbon PTV). Results of commissioning efforts, technical details and the achieved optimizations will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB181
About •	paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 25 August 2021
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MOPAB182	Automated Synchrotron Lattice Design and Optimisation Using a Multi-Objective Genetic Algorithm	network, lattice, synchrotron, superconducting-magnet	616
	X. Zhang, S.L. Sheehy The University of Melbourne, Melbourne, Victoria, Australia E. Benedetto TERA, Novara, Italy E. Benedetto CERN, Meyrin, Switzerland
	Funding: This work is partially supported by the Australian Government Research Training Program Scholarship. As part of the Next Ion Medical Machine Study (NIMMS), we present a new method for designing synchrotron lattices. A step-wise approach was used to generate random lattice structures from a set of feedforward neural networks. These lattice designs are optimised by evolving the networks over many iterations with a multi-objective genetic algorithm (MOGA). The final set of solutions represent the most effi- cient and feasible lattices which satisfy the design constraints. It is up to the lattice designer to choose a design that best suits the intended application. The automated algorithm presented here randomly samples from all possible lattice layouts and reaches the global optimum over many iterations. The requirements of an efficient extraction scheme in hadron therapy synchrotrons impose stringent constraints on the lat- tice optical functions. Using this algorithm allows us to find the global optimum that is tailored to these constraints and to fully utilise the flexibilities provided by new technology.
	Poster MOPAB182 [6.006 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB182
About •	paper received ※ 15 May 2021 paper accepted ※ 23 June 2021 issue date ※ 14 August 2021
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MOPAB196	Field tuning of the 1 MeV/n RFQ at KOMAC	rfq, ion-source, quadrupole, solenoid	662
	H.-J. Kwon, Y.-S. Cho, J.J. Dang, W.-H. Jung, D.-H. Kim, H.S. Kim, K.H. Kim, S. Lee Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
	Funding: This work was supported by the Korea Multi-purpose Accelerator Complex (KOMAC) operation funds through Ministry of Science and ICT (MIST) of Korean Government. A 1 MeV/n Radio-frequency Quadrupole (RFQ) is under development at Korea Multi-purpose Accelerator Complex (KOMAC), the purposes of which are swift ion beam irradiation and compact neutron source. The RFQ was designed to accelerate ions with mass to charge (A/q) ratio up to 2.5. The designed peak current was 10 mA with 10% duty ratio. The RFQ is four vane structure resonated at 200 MHz. It has total 40 frequency tuners. There are no dipole rods and resonant coupling plate because the mode separation was large enough and the length of the RFQ was only two times of the wavelength. In this paper, the development status and field tuning results of the 1 MeV/n RFQ are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB196
About •	paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 20 August 2021
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MOPAB198	Study on Magnet Sorting of the CSNS/RCS Dipoles	closed-orbit, MMI, neutron, controls	665
	Y. Li, Y.W. An IHEP, Beijing, People’s Republic of China Z.P. Li, S.Y. Xu DNSC, Dongguan, People’s Republic of China
	The 1.6GeV rapid cycling synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is a high-power pulsed proton machine aiming for 500kW output beam power. Now, the routine output beam power has been increased to 100kW. However, the horizontal bare orbit in the ring is large (15mm) and the number of correctors is small, which brings great challenges to the ramp-up of beam power. It is found that the bare orbit in AC mode is 3-4mm larger than that in DC mode. The reason is that the AC dipoles field error is larger than DC dipoles field error. Therefore, it is proposed to sort dipoles again according to the AC dipoles field error. In order to reduce the risk of beam commissioning, fewer magnets should to be moved to achieve smaller orbit. The best results of moving two to six magnets were calculated. After sorting, the orbit can be reduced by 3-4mm, which reduces the difficulty of orbit correction.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB198
About •	paper received ※ 16 May 2021 paper accepted ※ 21 May 2021 issue date ※ 14 August 2021
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MOPAB211	Beam Coupling Impedances of Ferrite-Loaded Cavities: Calculations and Measurements	cavity, impedance, resonance, coupling	696
	S.S. Kurennoy, R.C. McCrady LANL, Los Alamos, New Mexico, USA
	We have developed an efficient method of calculating impedances in cavities with dispersive ferrite dampers. The ferrite dispersive properties in the frequency range of interest are fitted in CST, which allows using both wakefield and lossy eigenmode solvers. A simple test cavity with or without ferrite inserts is explored both numerically and experimentally. The resonance frequencies and beam coupling impedances at cavity resonances are calculated with CST to understand the mode structure. The cavity transverse coupling impedances are also measured on a test stand using a two-wire method. We compare results of impedance calculations and measurements for a few different configurations, with and without ferrites, to ensure a complete understanding of the cavity resonances and their damping with ferrite. These results are important to provide adequate damping of undesired transverse modes in induction-linac cells.
	Poster MOPAB211 [1.105 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB211
About •	paper received ※ 10 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021
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MOPAB220	Towards Deterministic Design of MBA-Lattices	lattice, emittance, 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, emittance, 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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MOPAB232	Observation of Polarization-Dependent Changes in Higher-Order Mode Responses as a Function of Transverse Beam Position in Tesla-Type Cavities at FAST	cavity, HOM, electron, cryomodule	756
	R.M. Thurman-Keup, D.R. Edstrom, A.H. Lumpkin, P.S. Prieto, J. Ruan Fermilab, Batavia, Illinois, USA J.A. Diaz Cruz UNM-ECE, Albuquerque, USA J.A. Diaz Cruz, B.T. Jacobson, J.P. Sikora, F. Zhou SLAC, Menlo Park, California, USA
	Funding: FNAL supported by U.S. Department of Energy, Office of Science, under contract DE-AC02-07CH11359. SLAC supported by U.S. Department of Energy, Office of Science, under contract DE-AC02-76SF00515. Higher-order modes (HOMs) in superconducting rf cavities present problems for an electron bunch traversing the cavity in the form of long-range wakefields from previous bunches. These may dilute the emittance of the macropulse average, especially with low emittance beams at facilities such as the European X-ray Free-electron Laser (XFEL) and the upgraded Linac Coherent Light Source (LCLS-II). Here we present observations of HOMs driven by the beam at the Fermilab Accelerator Science and Technology (FAST) facility. The FAST facility features two independent TESLA-type cavities (CC1 and CC2) after a photocathode rf gun followed by an 8-cavity cryomodule. The HOM signals were acquired from cavities using bandpass filters of 1.75 ± 0.15 GHz, 2.5 ± 0.2 GHz, and 3.25 ± 0.2 GHz and recorded using an 8-GHz, 20 GSa/s oscilloscope. The frequency resolution obtained is sufficient to separate polarization components of many of the HOMs. These HOM signals were captured from CC1 and cavities 1 and 8 of the cryomodule for various initial trajectories through the cavities, and we observe correlations between trajectory, HOM signals, and which polarization component of a mode is affected.
	Poster MOPAB232 [2.144 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB232
About •	paper received ※ 20 May 2021 paper accepted ※ 25 May 2021 issue date ※ 10 August 2021
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MOPAB234	Analysis of the Chromatic Vertical Focusing Effect of Dipole Fringe Fields	focusing, simulation, optics, closed-orbit	760
	K. Hwang, C.E. Mitchell, R.D. Ryne LBNL, Berkeley, California, USA
	Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231 There have been questions regarding the impact of the dipole fringe-field models (used by accelerator codes including ELEGANT and MADX) on vertical chromaticity. Here, we analyze the cause of the disagreement among codes and suggest a correction.
	Poster MOPAB234 [0.486 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB234
About •	paper received ※ 20 May 2021 paper accepted ※ 01 June 2021 issue date ※ 23 August 2021
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MOPAB239	Simulation and Optimization of the Spin Coherence Time of Protons in a Prototype EDM Ring	quadrupole, storage-ring, simulation, polarization	771
	M. Vitz, A. Lehrach FZJ, Jülich, Germany R. Shankar INFN-Ferrara, Ferrara, Italy
	The matter-antimatter asymmetry might be understood by investigating the EDM (Electric Dipole Moment) of elementary charged particles. A permanent EDM of a subatomic particle violates time-reversal and parity symmetry at the same time and would be, with the currently achievable experimental accuracy, a strong indication for physics beyond the Standard Model. The JEDI-Collaboration (Jülich Electric Dipole moment Investigations) in Jülich is preparing a direct EDM measurement for protons and deuterons: first at the storage ring COSY (COoler SYnchrotron) and later at a dedicated storage ring. A prototype EDM ring is an intermediate step before building the final storage ring to demonstrate sufficient beam lifetime and SCT (Spin Coherence Time) in a pure electrostatic ring as well as in a storage ring with combined electric and magnetic bending elements. In order to study the effect of E-B-deflectors on the orbit and the spin motion, the software library Bmad is used. The first results of the optics and spin simulations, with a focus on the optimization of the SCT, towards the prototype EDM ring will be discussed.
	Poster MOPAB239 [0.560 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB239
About •	paper received ※ 17 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 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, emittance	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	emittance, 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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MOPAB254	Measurement of Horizontal Beam Size Using Sextupole Magnets	sextupole, quadrupole, storage-ring, positron	802
	J.A. Crittenden, K.E. Deitrick, H.X. Duan, G.H. Hoffstaetter, V. Khachatryan, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work is supported by National Science Foundation award number DMR-1829070. The quadratic dependence of sextupole fields on position results in a beam-size-dependent kick on a beam traversing a sextupole magnet. A change in sextupole strength changes the closed orbit and the tune of the beam in a storage ring. Measuring both therefore allows conclusions about the beam size in the sextupole. Here we derive the pertinent formula and discuss the applicability to storage rings. In particular we investigate the measurement accuracy that can be achieved at the Cornell High Energy Synchrotron Source. The Cornell Electron-positron Storage Ring underwent a major upgrade in 2018 with the goal of reducing the emittance by a factor of four. A variety of beam size measurement methods have been developed to monitor the positron beam size, including visible synchrotron light and interferometry. We investigate the sensitivity of the sextupole method and compare to other measurement techniques. The design horizontal emittance of the 6-GeV positron beam is about 30 nm-rad with typical beam sizes of about 1 mm, setting the scale for the required accuracy in the beam-size measurement.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB254
About •	paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 01 September 2021
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MOPAB262	First Thoughts on Lattices for a possible Metrology Light Source 2	lattice, emittance, 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	emittance, multipole, MMI, 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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MOPAB269	Three Approaches for Complete Measurement of the Transverse Beam Optics Along the Fermilab Muon Campus Extraction Line	quadrupole, extraction, optics, real-time	854
	B.D. Simons, M.J. Syphers Northern Illinois University, DeKalb, Illinois, USA D. Stratakis, M.J. Syphers Fermilab, Batavia, Illinois, USA
	Funding: This work was supported through grant DE-SC0020379 with the United States Department of Energy. Traditionally, the process of measuring the optical parameters of a beamline has employed the use of one of two standard methods, namely the three-screen method or a quadrupole magnet scan. Both require either an area of zero dispersion to perform the measurements or knowledge of the dispersion function and momentum spread beforehand in order to provide accurate results. There is however a third method that can be used to measure the standard optical parameters, the beam parameters, the dispersion function, and the momentum spread simultaneously. This method, aptly named the six-screen method, is an extension of the more standard three-screen method. Utilizing the simulation environment of G4beamline, we simulated the 8 GeV proton beam in the M4 beamline and measured the optical and beam parameters using the two standard approaches. Those results were then used as a reference to check the viability of employing the less standard six-screen method in the M4 line. If shown to be a viable option, the six-screen method could be used to retrieve the dispersion function and momentum spread of the beam without needing to change the energy of the beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB269
About •	paper received ※ 20 May 2021 paper accepted ※ 07 June 2021 issue date ※ 12 August 2021
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MOPAB284	Status of the Dedicated Electron Diagnostic Beamline at AXSIS	electron, diagnostics, MMI, controls	902
	H. Dinter, R.W. Aßmann, F. Burkart, M.J. Kellermeier DESY, Hamburg, Germany C. Lechner EuXFEL, Schenefeld, Germany
	Funding: The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 609920. AXSIS (Attosecond X-ray Science: Imaging and Spectroscopy) is a compact, accelerator-driven X-ray source currently under construction at DESY Hamburg. It comprises a THz-powered electron gun and THz-driven linac for all-optical electron extraction and acceleration to several MeV with the goal of providing X-rays generated by inverse Compton scattering for photon science experiments. For the commissioning and characterisation of the THz gun and linac the facility includes a dedicated accelerator testing area, for which an electron diagnostic beamline has been designed and is currently under construction. The challenges imposed by the AXSIS project on the development of the diagnostics beamline are the wide ranges of bunch charge (15 fC to 3 pC) and energy (5 MeV to 20 MeV) expected from the THz-driven accelerator as well as the limited available space of only ca. 2.5 metres length. In this contribution we present an overview of the design and the current commissioning status of the electron diagnostic beamline as well as plans for future steps.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB284
About •	paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 25 August 2021
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MOPAB304	Beam Diagnostics for Multi-Objective Bayesian Optimization at the Argonne Wakefield Accelerator Facility	emittance, diagnostics, 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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MOPAB345	Machine Learning with a Hybrid Model for Monitoring of the Protection Systems of the LHC	monitoring, operation, superconducting-magnet, machine-protect	1072
	C. Obermair, A. Apollonio, Z. Charifoulline, M. Maciejewski, A.P. Verweij CERN, Geneva, Switzerland C. Obermair, F. Pernkopf TUG, Graz, Austria
	The LHC is the world’s largest particle accelerator and uses a complex set of sophisticated and highly reliable machine protection systems to ensure a safe operation with high availability for particle physics production. The data gathered during several years of successful operation allow the use of data-driven methods to assist experts in finding anomalies in the behavior of those protection systems. In this paper, we derive a model that can extend the existing signal monitoring applications for the LHC protection systems with machine learning. Our hybrid model combines an existing threshold-based system with a SVM by using signals, manually validated by experts. Even with a limited amount of data, the SVM learns to integrate the expert knowledge and contributes to a better classification of safety-critical signals. Using this approach, we analyze historical signals of quench heaters, which are an important part of the quench protection system for superconducting magnets. Particularly, it is possible to incorporate expert decisions into the classification process and to improve the failure detection rate of the existing quench heater discharge analysis tool.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB345
About •	paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 01 September 2021
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MOPAB364	Shielded Pair Method for Cylindrical Surface Resistance Measurement at Cryogenic Temperature	factory, cryogenics, coupling, simulation	1132
	K. Brunner, S. Calatroni, F. Caspers CERN, Geneva, Switzerland D. Barna Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
	The shielded pair resonator method was already used in the past at CERN to measure the surface resistivity of the LHC beam screen both at room temperature and cryogenic temperature. We have refined and adapted the measurement to be able to measure other types of beam screens and also to operate in a strong dipolar magnetic field. This is necessary for testing the properties of HTS coated beam screens or the possible effects of coatings and surface treatments for e-cloud suppression. Several calibration runs were done at cryogenic temperatures (4.2 K) measuring the surface resistivity of a copper pipe to identify the precision, stability and reproducibility achievable using this method. This work describes the challenges of the measurement and ways to mitigate them.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB364
About •	paper received ※ 17 May 2021 paper accepted ※ 22 June 2021 issue date ※ 12 August 2021
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MOPAB374	Creating Exact Multipolar Fields in Accelerating RF Cavities via an Azimuthally Modulated Design	cavity, simulation, quadrupole, collider	1154
	L.M. Wroe, S.L. Sheehy JAI, Oxford, United Kingdom R. Apsimon Cockcroft Institute, Lancaster University, Lancaster, United Kingdom M. Dosanjh CERN, Meyrin, Switzerland S.L. Sheehy The University of Melbourne, Melbourne, Victoria, Australia
	In this paper, we present a novel method for designing RF structures with specifically tailored multipolar field contributions. This has a range of applications, including the suppression of unwanted multipolar fields or the introduction of wanted terms, such as for quadrupole focusing. In this article, we outline the general design methodology and compare the expected results to 3D CST simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB374
About •	paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 23 August 2021
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MOPAB384	Nb₃Sn Coating of Twin Axis Cavity for Accelerator Applications	cavity, linac, niobium, SRF	1175
	J.K. Tiskumara, S.U. De Silva, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA J.R. Delayen, H. Park, U. Pudasaini, C.E. Reece JLab, Newport News, Virginia, USA G.V. Eremeev Fermilab, Batavia, Illinois, USA
	Funding: Research supported by DOE Office of Science Accelerator Stewardship Program Award DE- SC0019399. Partially authored by Jefferson Science Associates under contract no. DEAC0506OR23177 A Superconducting twin axis cavity consisting of two identical beam pipes that can accelerate and decelerate beams within the same structure has been proposed for the Energy Recovery Linac (ERL) applications. There are two niobium twin axis cavities at JLab fabricated with the intention of later Nb₃Sn coating and now we are progressing to coat them using vapor diffusion method. Nb₃Sn is a potential alternate material for replacing Nb in SRF cavities for better performance and reducing operational costs. Because of advanced geometry, larger surface area, increased number of ports and hard to reach areas of the twin axis cavities, the usual coating approach developed for typical elliptical single-axis cavities must be evaluated and requires to be adjusted. In this contribution, we report the first results from the coating of a twin axis cavity and discuss current challenges with an outlook for the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB384
About •	paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 27 August 2021
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TUXC07	Modified Halbach Magnets for Emerging Accelerator Applications	permanent-magnet, quadrupole, collider, electron	1315
	S.J. Brooks 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 original circular Halbach magnet design creates a strong pure multipole field from permanent magnet pieces without intervening iron. This design has been extended recently at the CBETA 4-turn ERL, whose return loop includes combined-function (dipole+quadrupole) Halbach-derived magnets, plus a modular system of tuning shims to improve all 216 magnets’ relative field accuracy to better than 10^-3. This paper describes further modifications of the Halbach design enable a larger range of accelerator applications in the future: (1) open-midplane designs to allow synchrotron radiation in light sources and other high-energy electron rings, ERLs or RLAs to escape. (2) Quadrupole magnets with an oval aperture allow larger gradients than a circular aperture, provided the beam is more extended in one axis than the other, as usual for a quadrupole in a focussing system. These can be used in compact hadron therapy gantries. (3) New collider complexes often require multiple rings for acceleration or top-up, accumulation, collision and cooling. Multi-aperture permanent magnets are possible to cheaply and compactly build ring systems with several stable orbits separated by a few cm.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXC07
About •	paper received ※ 14 May 2021 paper accepted ※ 08 July 2021 issue date ※ 23 August 2021
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TUPAB008	Progress of the First-Turn Commissioning Simulations for HEPS	simulation, quadrupole, lattice, MMI	1349
	B. Wang, Z. Duan, D. Ji, Y. Jiao, Y.L. Zhao IHEP, Beijing, People’s Republic of China
	The High Energy Photon Source (HEPS) is 6 GeV, kilometer-scale, 4th generation storage ring light source. The lattice has an ultralow emittance and strong focusing such that the beam dynamics is very sensitive to the magnet misalignments and other error sources. Getting the first turn and establishing the closed orbit is essential for accelerator commissioning. This paper describes a simulation algorithm for achieving the first turn commission based on the latest HEPS storage ring lattice. We developed a new accelerator toolbox (AT)-based program for automatic optimizing the first turn commissioning. The algorithm and simulation results will be presented in this paper.
	Poster TUPAB008 [0.646 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB008
About •	paper received ※ 14 May 2021 paper accepted ※ 11 June 2021 issue date ※ 28 August 2021
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TUPAB017	Study of Conduction-Cooled Superconducting Quadrupole Magnets Combined with Dipole Correctors for the ILC Main Linac	quadrupole, linac, SRF, cavity	1375
	Y. Arimoto, S. Michizono, Y. Morikawa, N. Ohuchi, T. Oki, H. Shimizu, K. Umemori, X. Wang, A. Yamamoto, Y. Yamamoto, Z.G. Zong KEK, Ibaraki, Japan V.S. Kashikhin Fermilab, Batavia, Illinois, USA
	A superconducting rf (SRF) cryomodule for International Linear Collider(ILC) Main Linac equips focus/steering magnets. The magnets are "superferric" magnets with four superconducting (SC) race track coils conductively cooled from the cryomodule LHe supply pipe. The quadrupole field gradient and dipole field are 40 T/m and 0.1 T, respectively. The magnet length and iron-pole radius are 1 m and 0.045 m, respectively. It is known that dark current is generated at SRF cavities and accelerated through the following linac string. The dark current reaches and heats the SC magnets. It is estimated that the power deposition in the magnet may reach more than a few watts and temperature of the SC coils may locally reach to critical temperature of NbTi. It is important to make the magnet not reach quench with sufficient conduction cooling. We aim to realize the SC magnet which can stably operate under such condition. We plan to develop test coils made of three types of SC materials, NbTi, Nb₃Sn, and MgB₂ and study thermal characteristics and stability . We will develop a short model magnet, based on the test coil results. Here, we will present the magnet design study and the R&D plan.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB017
About •	paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 18 August 2021
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TUPAB019	A High-Resolution, Low-Latency, Bunch-by-Bunch Feedback System for Nano-Beam Stabilization	feedback, cavity, kicker, collider	1378
	R.L. Ramjiawan, D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich, P. Burrows, G.B. Christian, C. Perry JAI, Oxford, United Kingdom D.R. Bett CERN, Geneva, Switzerland N. Blaskovic Kraljevic ESS, Lund, Sweden G.B. Christian DLS, Oxfordshire, United Kingdom
	A low-latency, bunch-by-bunch feedback system employing high-resolution cavity Beam Position Monitors (BPMs) has been developed and tested at the Accelerator Test Facility (ATF2) at the High Energy Accelerator Research Organization (KEK), Japan. The feedback system was designed to demonstrate nanometer-level vertical stabilization at the focal point of the ATF2 and can be operated using either a single BPM to provide local beam stabilization, or by using two BPMs to stabilize the beam at an intermediate location. The feedback correction is implemented using a stripline kicker and the feedback calculations are performed on a digital board constructed around a Field Programmable Gate Array (FPGA). The feedback performance was tested with trains of two bunches, separated by 280ns, at a charge of ~1nC, where the vertical offset of the first bunch was measured and used to calculate the correction to be applied to the second bunch. The BPMs have been demonstrated to achieve an operational resolution of ~20nm. With the application of single-BPM and two-BPM feedback, beam stabilization of below 50nm and 41nm respectively has been achieved with a latency of 232ns.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB019
About •	paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 14 August 2021
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TUPAB040	Design Concept for the Second Interaction Region for Electron-Ion Collider	electron, detector, proton, optics	1435
	B.R. Gamage, V. Burkert, R. Ent, Y. Furletova, D.W. Higinbotham, A. Hutton, F. Lin, T.J. Michalski, V.S. Morozov, R. Rajput-Ghoshal, D. Romanov, T. Satogata, A. Seryi, A.V. Sy, C. Weiss, M. Wiseman, W. Wittmer, Y. Zhang JLab, Newport News, Virginia, USA E.C. Aschenauer, J.S. Berg, A. Jentsch, A. Kiselev, C. Montag, R.B. Palmer, B. Parker, V. Ptitsyn, F.J. Willeke, H. Witte BNL, Upton, New York, USA C. Hyde ODU, Norfolk, Virginia, USA P. Nadel-Turonski SBU, Stony Brook, New York, USA
	Funding: Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 and Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The possibility of two interaction regions (IRs) is a design requirement for Electron-Ion Collider (EIC). There is also a significant interest from the nuclear physics community to have a 2nd IR with measurement capabilities complementary to those of the 1st IR. While the 2nd IR will be in operation over the entire energy range of ~20GeV to ~140GeV center of mass (CM). The 2nd IR can also provide an acceptance coverage complementary to that of the 1st. In this paper, we present a brief overview and the current progress of the 2nd IR design in terms of the parameters, magnet layout, and beam dynamics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB040
About •	paper received ※ 24 May 2021 paper accepted ※ 31 August 2021 issue date ※ 30 August 2021
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TUPAB042	Large Radial Shifts in the EIC Hadron Storage Ring	hadron, closed-orbit, electron, insertion	1443
	S. Peggs, J.S. Berg, K.A. Drees, X. Gu, C. Liu, H. Lovelace III, Y. Luo, G.J. Marr, A. Marusic, F. Méot, R.J. Michnoff, V. Ptitsyn, G. Robert-Demolaize, M. Valette, S. Verdú-Andrés BNL, Upton, New York, USA K.E. Deitrick Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA B.R. Gamage JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The Electron Ion Collider will collide hadrons in the Hadron Storage Ring (HSR) with ultra-relativistic electrons in the Electron Storage Ring. The HSR design trajectory includes a large radial shift over a large fraction of its circumference, in order to adjust the hadron path length to synchronize collisions over a broad range of hadron energies. The design trajectory goes on-axis through the magnets, crab cavities and other components in the six HSR Insertion Regions. This paper discusses the issues involved and reports on past and future beam experiments in the Relativistic Heavy Ion Collider, which will be upgraded to become the HSR.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB042
About •	paper received ※ 18 May 2021 paper accepted ※ 15 June 2021 issue date ※ 21 August 2021
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TUPAB064	Specifications and Performance of a Chicane Magnet for the cERL IR-FEL	FEL, undulator, operation, operational-performance	1512
	N. Nakamura, K. Harada, N. Higashi, Y. Honda, R. Kato, C. Mitsuda, S. Nagahashi, T. Obina, H. Sakai, M. Shimada, H. Takaki, O.A. Tanaka KEK, Ibaraki, Japan Y. Lu Sokendai, 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 IR-FEL was constructed in the Compact ERL (cERL) at KEK from October 2019 to May 2020 for the purpose of developing high-power mid-infrared lasers for high-efficiency laser processing utilizing molecular vibrational absorption. The chicane magnet was newly installed between two IR-FEL undulators in the cERL in order to increase the FEL gain and pulse energy by converting the energy modulation to the density modulation in an electron bunch. It consists of three dipole magnets with laminated yokes made of 0.1-mm-thick permalloy sheets and the coil currents of the three magnets are independently controlled by three power supplies with the maximum current of 10 A. The maximum closed orbit bump made by the chicane magnetic field has the longitudinal dispersion(R56) of -6 mm. The coil-current ratio of the three dipole magnets was tuned after installation to make its orbit bumps closed and then the chicane magnet was used in the FEL operation. We present specifications and operational performance of the chicane magnet.
	Poster TUPAB064 [4.053 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB064
About •	paper received ※ 18 May 2021 paper accepted ※ 25 May 2021 issue date ※ 25 August 2021
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TUPAB087	Full Characterization of the Bunch-Compressor Dipoles for FLUTE	electron, linac, HOM, controls	1585
	Y. Nie, A. Bernhard, E. Bründermann, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, Y. Tong KIT, Karlsruhe, Germany
	Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research). The Ferninfrarot Linac- Und Test-Experiment (FLUTE) is a KIT-operated linac-based test facility for accelerator research and development as well as a compact, ultra-broadband and short-pulse terahertz (THz) source. As a key component of FLUTE, the bunch compressor (chicane) consisting of four specially designed dipoles will be used to compress the 40-50 MeV electron bunches after the linac down to single fs bunch length. The maximum vertical magnetic field of the dipoles reach 0.22 T, with an effective length of 200 mm. The good field region is ±40 mm and ±10.5 mm in the horizontal and vertical direction, respectively. The latest measurement results of the dipoles in terms of field homogeneity, excitation and field reproducibility within the good field regions will be reported, which meet the predefined specifications. The measured 3D magnetic field distributions have been used to perform beam dynamics simulations of the bunch compressor. Effects of the real field properties on the beam dynamics, which are different from that of the ASTRA built-in dipole field, will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB087
About •	paper received ※ 10 May 2021 paper accepted ※ 27 May 2021 issue date ※ 01 September 2021
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TUPAB102	A New 2nd Bunch Compression Chicane for the FLASH2020+ Project	quadrupole, vacuum, focusing, FEL	1618
	M. Vogt, J. Zemella DESY, Hamburg, Germany
	The first stage of the FLASH2020+ project is an upgrade of the FLASH injector beamline. Within this framework, the 2nd bunch compression chicane (BCC) will be completely redesigned. The old S-chicane will be replaced with a new C-chicane which is 3.5m shorter thereby generating space a new section for re-matching the beam from the injector into the linac. The new BCC will be equipped with quad/skew-quad units in both legs of the chicane to compensate correlations of the transverse degrees of freedom with the longitudinal ones. Since quadrupoles tend to have a circular bore, the chicane is designed with movable round vacuum chambers and movable dipoles for maintaining full flexibility in choosing the compression parameters. This article describes the technical details and introduces a thin-lens model of BCCs which allows analytical estimates on the effects of powering the quad/skew-quad units on optics parameters as well as estimates on the required strengths of these magnets in order to remove correlations of the magnitudes typically observed at FLASH.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB102
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 29 August 2021
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TUPAB175	ESSnuSB Linac and Transfer Line: Lattice Design and Error Studies	linac, lattice, proton, DTL	1805
	N. Blaskovic Kraljevic, M. Eshraqi, B.T. Folsom ESS, Lund, Sweden
	Funding: ESSnuSB has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 777419. The ESS neutrino superbeam (ESSnuSB) project is being studied as an upgrade to the European Spallation Source (ESS). This proposed upgrade consists of adding an H⁻ source to the existing beamline in order to send H⁻ pulses in between proton pulses, effectively doubling the beam power from 5 MW to 10 MW. In this contribution, we present the 2.5 GeV linear accelerator (linac) lattice and the design of the transfer line from the linac to the accumulator ring, where pulses would be stacked to achieve short proton pulses of high intensity. The results of error studies, quantifying the effect of accelerator imperfections and H⁻ ion stripping losses on the beam transport through the linac and transfer line, are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB175
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 31 August 2021
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TUPAB217	Effect of Undulators on Transverse Resonant Island Orbits	undulator, operation, diagnostics, optics	1927
	E.C.M. Rial, J. Bahrdt, P. Goslawski, A. Meseck, M. Ries, M. Scheer HZB, Berlin, Germany
	For one week in October 2020, BESSY II offered a Two Orbit mode to users for the first time. In this Two Orbit mode, the existence of transverse resonant island buckets* are exploited to store a second beam in the storage ring as an ’island orbit’, away from the primary beam axis. This mode was offered with free range of motion of the 12 out of vacuum undulators installed at the BESSY II ring. Diagnostics of the island orbit were limited to a single camera monitoring bending magnet radiation from a single dipole. A significant motion of the island orbit was observed on this diagnostic and correlated with undulator motion. This observation is reported, and simulations presented to demonstrate how this motion could arise. Correction schemes are suggested and discussed. Two Orbit - a report on the first scheduled week of TRIBs user operation at BESSY II, M. Ries et al, these proceedings *Proc. IPAC 2016, Busan, S Korea, paper THPMR017, p. 3427
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB217
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 22 August 2021
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TUPAB218	Fully Covariant Two-Particle Space-Charge Dynamics Using the Liénard-Wiechert Potentials	electromagnetic-fields, electron, space-charge, FEL	1931
	B.T. Folsom, E. Laface ESS, Lund, Sweden
	Space charge models typically assume instantaneous propagation of the electromagnetic fields between particles in a bunch, describing forces in the frame of the reference particle. In this paper, we construct a space-charge tracking code from the retarded Liénard-Wiechert potentials, which are covariant by design, in a Lagrangian formulation. Such potentials are manipulated with covariant derivatives to produce the necessary equations of motion that will be solved in a test system of two particles at various relative energies. Magnetic dipole moment dynamics are also evaluated where applicable.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB218
About •	paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 11 August 2021
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TUPAB231	Cooling of an Annular Beam by Using Nonlinear Effects	resonance, emittance, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB231
About •	paper received ※ 10 May 2021 paper accepted ※ 16 June 2021 issue date ※ 21 August 2021
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TUPAB237	Symplectic Tracking Through Field Maps	quadrupole, cavity, ion-source, radio-frequency	1992
	S.D. Webb RadiaSoft LLC, Boulder, Colorado, USA B.T. Folsom, E. Laface, R. Miyamoto ESS, Lund, Sweden
	For many applications, it is necessary to track particles using field maps, instead of an analytic representation of the fields which is typically not available. These field maps come about while designing elements such as realistic magnets or radiofrequency cavities, and represent the field geometry on a mesh in space. However, simple interpolation of the fields from the field maps does not guarantee that the resulting tracking scheme satisfies the symplectic condition. Here we present a general method to decompose the field-map potential in the sum of interpolating functions that produces, by construction, a symplectic integrator.
	Poster TUPAB237 [0.307 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB237
About •	paper received ※ 19 May 2021 paper accepted ※ 22 July 2021 issue date ※ 22 August 2021
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TUPAB258	Impact of Coherent Beam-Beam Interaction on the Landau Damping of the Transverse Coupled-Bunch Instability	electron, damping, coupling, proton	2062
	R. Li JLab, Newport News, Virginia, USA M. Blaskiewicz BNL, Upton, New York, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. In the EIC design, at high average-current operation, the transverse coupled-bunch instability (TCBI) induced by the long-range transverse resistive-wall wakefield in the electron storage ring (eSR) has a fast growth rate and requires efficient mitigation. A natural mitigation mechanism is provided by the beam-beam interaction at the interaction point (IP), which gives a strong Landau damping for the TCBI in the eSR. In this study, using a simplified simulation model, we investigate how this Landau damping from the beam-beam interaction behaves when the coherent beam-beam interaction at IP is considered. Our method and results will be presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB258
About •	paper received ※ 21 June 2021 paper accepted ※ 01 July 2021 issue date ※ 25 August 2021
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TUPAB260	A Beam Screen to Prepare the RHIC Vacuum Chamber for EIC Hadron Beams: Conceptual Design and Requirements	vacuum, electron, hadron, collider	2066
	S. Verdú-Andrés, M. Blaskiewicz, J.M. Brennan, X. Gu, R.C. Gupta, A. Hershcovitch, M. Mapes, G.T. McIntyre, J.F. Muratore, S.K. Nayak, S. Peggs, V. Ptitsyn, R. Than, J.E. Tuozzolo, D. Weiss 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 Electon Ion Collider (EIC) hadron ring will use the existing Relativistic Heavy Ion Collider storage rings, including the superconducting magnet arcs. The vacuum chambers in the superconducting magnets and the cold mass interconnects were not designed for EIC beams and so must be updated to reduce its resistive-wall heating and to suppress electron clouds. To do so without compromising the EIC luminosity goal, a stainless steel beam screen with co-laminated copper and a thin layer of amorphous carbon will be installed. This paper describes the main requirements that our solution for the hadron ring vacuum chamber needs to satisfy, including impedance, aperture limitations, vacuum, thermal and structural stability, mechanical design, installation and operation. The conceptual design of the beam screen currently under development is introduced.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB260
About •	paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 12 August 2021
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TUPAB319	SNS Credited Beam Power Limit System Preliminary Design	PLC, timing, target, controls	2242
	C. Deibele ORNL, Oak Ridge, Tennessee, USA K.L. Mahoney ORNL RAD, Oak Ridge, Tennessee, USA
	The Controls Group at the Spallation Neutron Source (SNS) is designing a programmable signal processor based credited safety control that calculates pulsed beam power based on beam kinetic energy and charge. The system must reliably shut off the beam if the average power exceeds 2.145 MW averaged over 60 seconds. This paper discusses architecture and design choices needed to develop the system under the auspices of a programmable radiation-safety credit control.
	Poster TUPAB319 [1.925 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB319
About •	paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 25 August 2021
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TUPAB359	Magnetic Field Measurement and Beam Performance Test of Ceramics Chamber with Integrated Pulsed Magnet at KEK-PF	vacuum, experiment, survey, kicker	2352
	Y. Lu Sokendai, Ibaraki, Japan K. Harada, Y. Kobayashi, C. Mitsuda, S. Nagahashi, T. Nogami, T. Obina, R. Takai, H. Takaki, T. Uchiyama, A. Ueda KEK, Ibaraki, Japan
	An air-core magnet named Ceramics Chamber with integrated Pulsed Magnet(CCiPM) is being developed at the photon factory of KEK(KEK-PF), which will have several applications for the future light source. One prototype has been developed as a dipole kicker, whose bore is only 30mm. Due to the type and structure, it’s expected to have strong magnetic field and high repetition rate. After finishing the offline measurement of magnetic field and evaluation of vacuum tightness, the CCiPM was installed in the beam transport-dump line of PF to have an online beam performance and durability test. The results of the magnetic field measurement and beam performance test will be reviewed.
	Poster TUPAB359 [1.164 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB359
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 16 August 2021
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TUPAB361	Study and Design of a Fast Switching Magnet for the MYRRHA Project	linac, proton, optics, beam-transport	2356
	E. Froidefond, F. Bouly, P.-O. Dumont LPSC, Grenoble Cedex, France D. Vandeplassche SCK•CEN, Mol, Belgium
	Funding: Work supported by SCK•CEN, CNRS/IN2P3, Univ. Grenoble Alpes. The MYRRHA project aims at building an Accelerator Driven System demonstrator, which consists of two injectors and a superconducting linac. The proton beam from the first injector accelerated up to 17 MeV goes to the linac (600 MeV) through a Medium Energy Beam Transfer line (MEBT). Whereas in the meantime, the beam from the second injector is sent to a beam dump. In case of failure in the first injector, the beam of the awaiting injector is sent to the linac. A switching magnet located at the junction of the two injection lines performs this beam switch in less than 1.5 seconds. A magnetic design and a mechanical structure of this magnet proposed to the MYRRHA project are presented. *emmanuel.froidefond@lpsc.in2p3.fr
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB361
About •	paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 23 August 2021
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TUPAB364	Dipole CR FAIR	HOM, simulation, storage-ring, experiment	2367
	K.K. Riabchenko, A.Yu. Pakhomov, T.V. Rybitskaya, A.A. Starostenko, A.S. Tsyganov, K.V. Zhiliaev BINP SB RAS, Novosibirsk, Russia
	The design of CR dipole magnets (24+2 pieces) for the FAIR project in Germany began in 2014 at BINP. CR is a special storage ring where the main emphasis is placed on efficient stochastic pre-cooling of intense beams of stable ions, rare isotopes, or antiprotons. This type of magnet is an iron-based electromagnet with a straight pole, sector form is realized by cutting ends. The maximum field value is 1.6 T. The integrated over the length of the magnet field quality as a function of radius is dBl/Bl = ± 10^-4 with 190 mm good field region as required from the beam dynamics simulations. This challenging field quality is necessary mainly for precise experiments with ion beam in the ISO regime. Below 1.6 T the value dBl/Bl can be higher with a linear approximation up to ± 2.5× 10^-4 at the field level of 0.8 T. The first prototype has been manufactured at the end of 2020. Here we describe features of the dipole, 3D calculations, and measurements of the magnetic field.
	Poster TUPAB364 [1.587 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB364
About •	paper received ※ 09 May 2021 paper accepted ※ 31 May 2021 issue date ※ 28 August 2021
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TUPAB368	Design of the Longitudinal Gradient Dipole Magnets for HALF	permanent-magnet, storage-ring, lattice, emittance	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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB368
About •	paper received ※ 15 May 2021 paper accepted ※ 02 June 2021 issue date ※ 10 August 2021
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TUPAB369	A Fast Non-Linear Model for the EBS Combined Sextupole-Corrector Magnets	sextupole, SRF, multipole, quadrupole	2381
	G. Le Bec ESRF, Grenoble, France
	Corrector are often integrated in higher order accelerator magnets. In the new ESRF-EBS storage ring, the sextupoles include additional windings allowing for dipole and skew quadrupole corrections. The accurate modelization of such magnets is not as trivial as it may appear, due to their non-linearities and to the crosstalk between their channels. Changing any corrector current induce non-linear errors in the other corrector channels and in the main sextupole strength, making difficult the trimming of the magnets. A model based on a non-linear excitation curve and quadratic contributions from corrector currents was developed. This model is very fast and was included in the accelerator control system to compute the corrector currents in real-time. It was tested against 3D magnetic simulations and magnetic measurements and compared to a simpler matrix-based model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB369
About •	paper received ※ 17 May 2021 paper accepted ※ 31 August 2021 issue date ※ 22 August 2021
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TUPAB370	Development of Long Coil Dynamic Magnetic Field Measurement System for Dipole Magnets of HEPS Booster	booster, interface, storage-ring, injection	2384
	Y.Q. Liu, C.D. Deng, W. Kang, L. Li, S. Li, X. Wu, Y.W. Wu, J.X. Zhou IHEP, Beijing, People’s Republic of China C.D. Deng, Y.W. Wu DNSC, Dongguan, People’s Republic of China
	A magnetic field measurement system for dipole magnets of High Energy Photon Source Booster is designed and developed. The system uses the long coil upflow method to measure the dynamic integral field of the magnet, and the long coil transverse-translation method to measure the integral field distribution error of the magnet. In this paper, the design and implementation of the magnetic measuring system are introduced in detail, and the magnetic field measurement results of the prototype magnet are shown. The measurement results show that the repeatability of the dynamic integral field measurement system is about 2 in 10,000, and the repeatability of the uniform distribution of the integral field is better than 1 in 10,000, which meets the test requirements of the discrete integral field of bulk magnets ±1 parts per thousand and the uniformity of the integral field ±5×10-4@6GeV and ±1×10^-3 @0.5GeV.
	Poster TUPAB370 [1.475 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB370
About •	paper received ※ 16 May 2021 paper accepted ※ 16 June 2021 issue date ※ 17 August 2021
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TUPAB378	Superconducting Dipole Magnets for the SIS100 Synchrotron	synchrotron, multipole, operation, simulation	2401
	F. Kaether, P. Aguar Bartolome, A. Bleile, G. Golluccio, J. Ketter, P. Kosek, F. Kurian, V. Marusov, J.P. Meier, S.S. Mohite, C. Roux, P.J. Spiller, K. Sugita, A. Szwangruber, P.B. Szwangruber, A. Warth, H.G. Weiss GSI, Darmstadt, Germany
	The Facility for Antiproton and Ion Research (FAIR) is currently under construction at GSI Darmstadt, Germany. For its main accelarator, the SIS100 synchrotron, 110 superconducting dipole magnets has been produced and extensively tested. The fast-ramped Nuclotron-type superferric dipoles were manufactured with high effort regarding a precise magnetic field which could be proven by magnetic field measurements with high accuracy. Stable operation conditions at 4.5 K were achieved including an excellent quench behaviour and precise geometrical and electrical properties. An overview on design, production, operation, tests and measurement results will be given.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB378
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 10 August 2021
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TUPAB379	Superconducting Magnets for Super-FRS: Production and Testing Status	quadrupole, superconductivity, sextupole, superconducting-magnet	2405
	H. Müller, A. Chiuchiolo, E.J. Cho, G. Golluccio, F. Greiner, P. Kosek, M. Michels, C. Roux, K. Sugita, V.V. Velonas, M. Winkler GSI, Darmstadt, Germany H. Allain, A. Madur CEA-IRFU, Gif-sur-Yvette, France A. Borceto, G. Drago, G. Valesi ASG, Genova, Italy M. Garcia Escudero, M. Lopez, J. Lucas Elytt Energy, Madrid, Spain G. Riddone, S. Russenschuck CERN, Geneva, Switzerland
	The Super FRS is a two-stage in flight separator to be built next to the site of GSI, Darmstadt, Germany as part of FAIR (Facility for Anti-proton and Ion Research). Its three branches allow to carry out a wide variety of experiments. Due to the large acceptance needed, the magnets of the Super-FRS require a large aperture and therefore only a superconducting solution is feasible. A superferric design was chosen in which the magnetic field is shaped by an iron yoke. For the dipole magnets only the superconducting coils are in a cryostat. These magnets are manufactured by Elytt Energy (Spain). The multiplets, assemblies of quadrupoles and higher order multipole magnets, are completely immersed in a liquid Helium bath. They are being built at ASG (Italy). The first of two first of series multiplets, a short assembly containing 2 magnets, was tested at a dedicated test facility at CERN (Switzerland). The 2nd FoS multiplet, containing 9 magnets, and the FoS dipole will be tested soon. Series production of the multiplets has started. In this paper we will present the status of production and testing of the different superconducting magnets for Super-FRS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB379
About •	paper received ※ 19 May 2021 paper accepted ※ 31 August 2021 issue date ※ 16 August 2021
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TUPAB381	Thermal Analysis of the RHIC Arc Dipole Magnet Cold Mass with the EIC Beam Screen	vacuum, electron, hadron, cryogenics	2413
	S.K. Nayak, M. Anerella, M. Blaskiewicz, J.M. Brennan, R.C. Gupta, M. Mapes, G.T. McIntyre, S. Peggs, R. Than, J.E. Tuozzolo, S. Verdú-Andrés, D. Weiss BNL, Upton, New York, USA
	Funding: Funding agency Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The EIC will make use of the existing RHIC storage rings with their superconducting (SC) magnet arcs. A stainless-steel beam screen with co-laminated copper and a thin amorphous carbon (aC) film on the inner surface will be installed in the beam pipe of the SC magnets. The copper will reduce the beam-induced resistive-wall (RW) heating from operation with the higher intensity EIC beams, that if not addressed would make the magnets quench. Limiting the RW heating is also important to achieve an adequately low vacuum level. The aC coating will reduce secondary electron yield which could also cause heating and limit intensity. Among all the RHIC SC magnets, the arc dipoles present the biggest challenge to the design and installation of beam screens. The arc dipoles, which make up for 78% (2.5 km) length of all SC magnets in RHIC, expect the largest RW heating due to their smallest aperture. These magnets are also the longest (9.45 m each), thus experiencing the largest temperature rise over their length, and have a large sagitta (48.5 mm) that increases the difficulty to install the beam screen in place. This paper presents a detailed thermal analysis of the magnet-screen system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB381
About •	paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 23 August 2021
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TUPAB386	Design Study of the Nb₃Sn Cos-Theta Dipole Model for FCC-hh	superconductivity, collider, FEL, FEM	2421
	R.U. Valente La Sapienza University of Rome, Rome, Italy S. Burioli, P. Fabbricatore, S. Farinon, F. Levi, R. Musenich, A. Pampaloni INFN Genova, Genova, Italy E. De Matteis, M. Statera INFN/LASA, Segrate (MI), Italy F. Lackner, D. Tommasini CERN, Meyrin, Switzerland S. Mariotto, M. Prioli INFN-Milano, Milano, Italy M. Sorbi Universita’ degli Studi di Milano & INFN, Segrate, Italy
	In the context of the Future Circular Collider hadron-hadron (FCC-hh) R&D program, the Italian Institute of Nuclear Physics (INFN), in collaboration with CERN, is responsible for designing and constructing the Falcon Dipole (Future Accelerator post-LHC Costheta Optimized Nb₃Sn Dipole), which is an important step towards the construction of High Field Nb₃Sn magnets for a post LHC collider. The magnet is a short model with one aperture of 50 mm and the target bore field is 12 T (14 T ’ultimate’ field). The dipole is pre-loaded with the Bladder&Key technique to minimize the stress on the coils at room temperature, which are prone to degradation because of the Nb₃Sn cable strain-sensitivity. The electro-mechanical 2D design is focused on the performance, the field quality and the quench protection, with emphasis to the stresses on the the conductor. The Falcon Dipole has been modelled in a 3D FEM to determine the peak field distribution and the influence of the coil ends on the field quality.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB386
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 19 August 2021
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WEPAB003	Overview of the Magnets Required for the Interaction Region of the Electron-Ion Collider (EIC)	electron, hadron, quadrupole, collider	2578
	H. Witte, K. Amm, M. Anerella, J. Avronsart, A. Ben Yahia, J.P. Cozzolino, R.C. Gupta, H.M. Hocker, P. Kovach, G.J. Mahler, A. Marone, R.B. Palmer, B. Parker, S.R. Plate, C.E. Runyan, J. Schmalzle 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 planned electron-ion collider (EIC) at Brookhaven National Laboratory (BNL) is designed to deliver a peak luminosity of 1x10³⁴ cm^-2 s^-1. This paper presents an overview of the magnets required for the interaction region of the BNL EIC. To reduce risk and cost the IR is designed to employ conventional NbTi superconducting magnets. In the forward direction the magnets for the hadrons are required to pass a large neutron cone and particles with a transverse momentum of up to 1.3 GeV/c, which leads to large aperture requirements. In the rear direction the synchrotron radiation fan produced by the electron beam must not hit the magnet apertures, which determines their aperture. For the forward direction a mostly interleaved scheme is used for the optics, whereas for the rear side 2-in-1 magnets are employed. We present an overview of the EIC IR magnet design including the forward spectrometer magnet B0.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB003
About •	paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 29 August 2021
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WEPAB026	Optics Measurements and Correction Plans for the HL-LHC	coupling, optics, luminosity, dynamic-aperture	2656
	T.H.B. Persson, X. Buffat, F.S. Carlier, R. De Maria, J. Dilly, E. Fol, D. Gamba, H. Garcia Morales, A. García-Tabarés Valdivieso, M. Giovannozzi, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, P.K. Skowroński, F. Soubelet, R. Tomás García, F.F. Van der Veken, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt CERN, Geneva, Switzerland J.M. Coello de Portugal PSI, Villigen PSI, Switzerland
	The High Luminosity LHC (HL-LHC) will require stringent optics correction to operate safely and deliver the design luminosity to the experiments. In order to achieve this, several new methods for optics correction have been developed. In this article, we outline some of these methods and we describe the envisioned strategy of how to use them in order to reach the challenging requirements of the HL-LHC physics program.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB026
About •	paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021
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WEPAB027	Optics Correction Strategy for Run 3 of the LHC	coupling, optics, MMI, quadrupole	2660
	T.H.B. Persson, R. De Maria, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, F. Soubelet, R. Tomás García, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt CERN, Geneva, Switzerland J.F. Cardona UNAL, Bogota D.C, Colombia
	The Run 3 of the LHC will continue to provide new challenges for optics corrections. In order to succeed and go beyond what was achieved previously, several new methods to measure and correct the optics have been developed. In this article we describe these methods and outline the plans for the optics commissioning in 2022.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB027
About •	paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021
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WEPAB032	Studies of the Short-Range Wakefields for the Electron Storage Ring in the Electron Ion Collider	simulation, electron, vacuum, wakefield	2675
	G. Wang, M. Blaskiewicz, A. Blednykh, M.P. Sangroula 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. During the estimates of impedance budget for the Electron Storage Ring (ESR) of Electron-Ion Collider (EIC), various codes, including GdfidL, CST and ECHO3D, have been used to calculate the short-range wake-fields due to the vacuum components. The ECHO 3D code demonstrates more reliable results for the tapered type of structures rather than the GdfidL code, where the stepsize needs to be dramatically decreased to achieve a high-performance calculation. Impedance of the following components are discussed and compared in details: Interaction Region (IR) chamber, bellows, and synchrotron radiation mask (flange absorber).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB032
About •	paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 24 August 2021
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WEPAB089	Conceptual Design of Booster Synchrotron for Siam Photon Source II	booster, synchrotron, lattice, focusing	2795
	S. Krainara, S. Klinkhieo, P. Klysubun, T. Pulampong, P. Sudmuang SLRI, Nakhon Ratchasima, Thailand
	Funding: Synchrotron Light Research Institute (Public organization) A project on a 3.0 GeV Siam Photon Source II (SPS-II) has been started. The storage ring of SPS-II was designed to obtain an electron beam with a low-emittance below 1 nm-rad. The SPS-II injector mainly consists of a 150 MeV linac and a full-energy booster synchrotron. The booster synchrotron will be installed in the same tunnel as the storage ring, with a total circumference of 304.829 meters. The proposed lattice of the booster contains 40 modified FODO cells with combined function magnets. This lattice achieves a small beam emittance less than 10 nm-rad at 3 GeV, which can provide a high injection efficiency for top-up operation. The conceptual design for SPS-II booster synchrotron is presented in this work.
	Poster WEPAB089 [1.187 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB089
About •	paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 24 August 2021
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WEPAB150	Monotron Beam Break Up Instability Analysis	HOM, cavity, klystron, resonance	2968
	V. Volkov, V.M. Petrov BINP SB RAS, Novosibirsk, Russia
	New features of monotron beam break up (BBU) instability such as the typing of high order monopole modes (HOMs)in each cavity by two classes one of them are stable and other ones are unstable, HOM effective quality factor depending on average beam current, and normalized invariable threshold current individually characterizes each HOM are investigated in this article in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB150
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 31 August 2021
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WEPAB151	Regenerative Beam Break Up Instability Analysis	cavity, HOM, linac, experiment	2971
	V. Volkov, V.M. Petrov BINP SB RAS, Novosibirsk, Russia
	New features of regenerative beam break up (BBU) instability such as the typing of high order dipole modes (HOMs)in each cavity by two classes, one of them are stable and other ones are unstable, HOM effective quality factor depending on average beam current, and normalized invariable threshold current individually characterizes each HOM are investigated in this article in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB151
About •	paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 01 September 2021
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WEPAB180	Design and Beam Dynamics Studies of a Novel Compact Recoil Separator Ring for Nuclear Research with Radioactive Beams	ISOL, optics, quadrupole, operation	3031
	J. Resta-López UVEG, Burjasot (Valencia), Spain A.P. Foussat, G. Kirby CERN, Geneva, Switzerland I. Martel University of Huelva, Huelva, Spain V. Rodin The University of Liverpool, Liverpool, United Kingdom V. Rodin Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work was supported by the Generalitat Valenciana under grant agreement CIDEGENT/2019/058 The recent development of radioactive beam facilities has significantly expanded the capabilities for investigating the structure of the atomic nucleus and the nuclear interaction. For instance, the HIE-ISOLDE facility at CERN delivers presently the largest range of low-energy radioactive beam available worldwide. This energy range is ideal for the study of nuclear structure, low-energy dynamics and astrophysics by using nucleon transfer, Coulomb excitation and deep inelastic reactions. All these studies require an efficient and high-resolution recoil separator for the clear identification of medium and large mass reaction fragments. To meet these needs, we propose a versatile recoil separator for radioisotopes based on a compact storage ring, the Isolde Superconducting Recoil Separator (ISRS) formed of superconducting combined-function nested magnets with both, bending and focusing/defocusing functions. The ISRS is designed to operate in high momentum acceptance and isochronous modes. In this paper, we present the optics design and detailed beam dynamics studies for the performance characterisation.
	Poster WEPAB180 [3.619 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB180
About •	paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 31 August 2021
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WEPAB188	New Method to Search for Axion-Like Particles Demonstrated with Polarized Beam at the COSY Storage Ring	polarization, resonance, storage-ring, experiment	3057
	S. Karanth Jagiellonian University, Kraków, Poland
	The axion was originally proposed to explain the small size of CP violation in quantum chromodynamics. It might be a candidate for dark matter in the universe. Axions or axion-like particles (ALPs) when coupled to gluons induce an oscillating Electric Dipole Moment (EDM) along the nucleon’s spin direction. At the Cooler Synchrotron (COSY) in Jülich, this principle was used to perform a first test experiment to search for ALPs using an in-plane polarized deuteron beam. If the spin precession frequency equals the EDM oscillation frequency, a resonance occurs that accumulates the rotation of the polarization out of the ring plane. Since the axion frequency is unknown, the beam momentum was ramped to search for a vertical polarization jump that would occur when the resonance is crossed. At COSY, four beam bunches with different polarization directions were used to make sure that no resonance was missed because of the unknown relative phase between the polarization precession and the EDM oscillations. We scanned a frequency window of about a 1-kHz width around the spin precession frequency of 121 kHz. This talk will describe the experiment and show preliminary results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB188
About •	paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 31 August 2021
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WEPAB211	Lattice Design of the Beam Transfer Line (BTL) from PIP-II LINAC to the Booster at Fermilab	booster, lattice, septum, power-supply	3120
	M. Xiao Fermilab, Batavia, Illinois, USA
	PIP-II beam transfer line (BTL) to transport the beam from PIP-II Linac to the Booster ring at Fermilab. The latest design eliminates rolling the dipoles in the beam line to cross over the Tevatron tunnel. Also re-designed is the lattice in the region of the Booster Injection to meet the request of the civil construction needs and accommodate the constrains of the Booster injection request. A beam line to the beam absorber (BAL) is designed based on the request from the results of Mars simulations and ANASYS calculation of the absorber. Simulations with dipole and quadrupole field errors for the Beam Transport Line (BTL) to the Booster, which provides the specifications for all the magnets and Power supplies, will be presented too.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB211
About •	paper received ※ 20 May 2021 paper accepted ※ 08 July 2021 issue date ※ 31 August 2021

Paper

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Other Keywords

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Power Deposition in Superconducting Dispersion Suppressor Magnets Downstream of the Betatron Cleaning Insertion for HL-LHC

proton, collimation, simulation, operation

37

A. Waets, C. Bahamonde Castro, E. Belli, R. Bruce, N. Fuster-Martínez, A. Lechner, A. Mereghetti, S. Redaelli, M. Sabaté-Gilarte, E. Skordis
CERN, Meyrin, Switzerland

Funding: Research supported by the HL-LHC project
The power deposited in dispersion suppressor magnets downstream of the Large Hadron Collider (LHC) betatron cleaning insertion is governed by off-momentum particles scattered out of the primary collimators. In order to mitigate the risk of magnet quenches during periods of short beam lifetime in future High-Luminosity (HL-LHC) operation, new dispersion suppressor (DS) collimators are considered for installation (one per beam). In this paper, we present FLUKA simulations for both protons and Pb ions at 7 TeV, predicting the power deposition in the DS magnets, including the new higher-field dipoles 11T which are needed to integrate the collimator in the cold region next to the cleaning insertion. The simulated power deposition levels for the adopted HL-LHC collimator configuration and settings are used to assess the quench margin by comparison with the present estimated quench levels.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB001

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paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 16 August 2021

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MOPAB014

First High Spin-Flip Efficiency for High Energy Polarized Protons

polarization, resonance, proton, experiment

84

H. Huang, J. Kewisch, C. Liu, A. Marusic, W. Meng, F. Méot, P. Oddo, V. Ptitsyn, V.H. Ranjbar, T. Roser
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 order to minimize the systematic errors for the Relativistic Heavy Ion Collider (RHIC) spin physics experiments, flipping the spin of each bunch of protons during the stores is needed. Experiments done with single RF magnet at energies less than 2 GeV have demonstrated a spin-flip efficiency over 99%. At high energy colliders with Siberian snakes, a single magnet spin flipper does not work because of the large spin tune spread and the generation of multiple, overlapping resonances. Over past decade, RHIC spin flipper design has evolved and a sophisticated spin flipper, constructed of nine-dipole magnets, was developed to flip the spin in RHIC. A special optics choice was also used to make the spin tune spread very small. In recent experiment, 97% spin-flip efficiency was measured at both 24 and 255 GeV for the first time. The results show that efficient spin flipping can be achieved at high energies.

Poster MOPAB014 [0.984 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB014

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paper received ※ 16 May 2021 paper accepted ※ 08 June 2021 issue date ※ 20 August 2021

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MOPAB026

RHIC Delayed Abort Experiments

experiment, kicker, injection, quadrupole

126

M. Valette, D. Bruno, K.A. Drees, K.M. Hartmann, G. Heppner, K. Mernick, C. Mi, J.-L. Mi, R.J. Michnoff, J. Morris, F. Orsatti, E. Rydout, T. Samms, J. Sandberg, V. Schoefer, C. Schultheiss, T.C. Shrey, C. Theisen
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.
For RHIC to operate at its top energy (100 GeV/n) while protecting the future sPHENIX detector, spontaneous and asynchronous firing of abort kicker modules (pre-fires) have to be avoided. A new triggering circuit for the abort kickers was implemented with relatively slow mechanical relays in series with the standard fast thyratron tubes. The relays prevents unwanted pre-fires during operation, but comes at the expense of a long latency - about 7 milliseconds - between the removal of beam permit and the actual firing of the abort kickers. Protection considerations of RHIC’s superconducting magnets forbid delaying energy extraction from the main dipoles and quadrupoles for too long after a quench. The beam has thus to circulate in both RHIc rings for a few milliseconds as the current in dipole and quadrupole circuit is being extracted. We present the results of delayed abort experiments conducted in July 2018 with the analysis of fast orbit and tune measurements and discuss the safety implications of this implementation for future RHIC operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB026

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paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 23 August 2021

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MOPAB058

Swap-Out Safety Tracking for the Advanced Photon Source Upgrade

photon, simulation, electron, power-supply

249

M. Borland, J.S. Downey, M.S. Jaski
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 will operate in swap-out mode, which is similar to top-up but involves complete replacement of individual depleted bunches in a single shot. As with top-up, safety is a concern given that this process will take place with beamline shutters open. We describe the methods used to model swap-out safety, including creation and validation of a full ring lattice based on 3D field maps. We also describe a new method of implementing complex, intersecting channels for electron beams and photon beams, as well as a method of easily identifying potentially dangerous stray particles. Numerous potential errors (e.g., magnet shorts) were modeled, giving a reliable indication of performance of proposed stored beam and magnet interlocks.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB058

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paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 29 August 2021

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MOPAB059

Tools for Use of Generalized Gradient Expansions in Accelerator Simulations

lattice, simulation, septum, quadrupole

253

M. Borland, R.R. Lindberg, R. Soliday, A. Xiao
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.
A common assumption in simulation of accelerators is that the magnets can be approximated using a hard-edge model, perhaps with some edge effects implemented in an impulse approximation. This is usually a good assumption but ignores details of the longitudinal variation of the magnetic fields, which makes it straightforward to implement symplectic tracking. Use of generalized gradient expansions* provides an alternative approach that can suppress numerical deficiencies that may be present in computed or measured 3D field maps. However, the computation of the expansions is not particularly straightforward. In this note, we describe several recently-developed tools that make this process fairly painless and allow tracking with such expansions in the program ELEGANT**. We show several examples of using the tools for simulations related to the Advanced Photon Source Upgrade.
* M. Venturini et al., NIM A 427, 387 (1999).
** M. Borland, Advanced Photon Source LS-287, September 2000

Poster MOPAB059 [4.311 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB059

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paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 18 August 2021

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MOPAB062

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

lattice, emittance, 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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MOPAB089

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

lattice, storage-ring, quadrupole, emittance

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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MOPAB092

Project of Wuhan Photon Source

storage-ring, cavity, injection, linac

346

H.H. Li, Y. Deng, J.H. He, Y. Nie, L. Tang, J. Wang, Y.X. Zhu
IAS, Wuhan City, People’s Republic of China

Wuhan Photon Source (WHPS) has been designed as a fourth-generation light source, which consists of a low energy storage ring (1.5 GeV), a medium energy storage ring (4.0 GeV), and a linac working as a full energy injector. It has been planned to build the low energy light source first as the Phase I project, and then the medium energy light source after its completion. The low energy storage ring has been optimized with the main design parameters as following: An 8-cell, 500 mA storage ring, with a circumference of 180 m and nature emittance 238.4 pm-rad. Based on hybrid-7BA lattice structure, it reaches the soft X-ray diffraction limit. And at the middle of each cell, a 3.5 T superB magnet is used to extend the photon energy to the hard X-ray region. The swap-out injection is chosen due to the small dynamic aperture and a full energy S-band LINAC will be used as its injector. A 3rd harmonic cavity is designed for bunch lengthening to keep a sufficient lifetime. More details of the WHPS phase I project will be described in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB092

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paper received ※ 10 June 2021 paper accepted ※ 23 June 2021 issue date ※ 24 August 2021

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MOPAB127

Construction of an Impedance Model for Diamond-II

impedance, simulation, lattice, cavity

455

R.T. Fielder, T. Olsson
DLS, Oxfordshire, United Kingdom

Impedance models for accelerators have traditionally been presented in a static form, usually as tables or spreadsheets which must be read manually. As part of the Diamond-II upgrade work, we have developed an impedance model using a lattice structure. This allows more direct integration with simulation codes while keeping important information easily human readable. We present here a description of this implementation method, along with an overview of the Diamond-II impedance model derived from the latest engineering design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB127

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paper received ※ 18 May 2021 paper accepted ※ 20 May 2021 issue date ※ 11 August 2021

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MOPAB178

Systematic Effects Limiting the Sensitivity of "Magic Energy" Proton EDM Rings

proton, betatron, pick-up, focusing

602

C. Carli, M. Haj Tahar
CERN, Geneva, Switzerland

Proposals to measure a possible Electric Dipole Moment (EDM) of protons in an electro-static storage ring are studied by a world-wide community. The machine is operated at the so-called "magic energy" to satisfy the "frozen spin" condition such that, without imperfections and with the well known magnetic moment of the particle, the spin is always oriented parallel to the direction of movement. The effect of a finite EDM is a build-up of a vertical spin component. Any effect, other than a finite EDM, leading as well to a build-up of a vertical spin limits the sensitivity of the experiment. Such "systematic effects" are caused by machine imperfections, such as magnetic fields inside the magnetic shield surrounding the ring, and misalignments of electro-static elements or of the RF cavity. Operation of the machine with counter-rotating beams helps mitigating some of the effects. The most dangerous effects are those, which cannot be disentangled from an EDM by combining measurements from both counter-rotating beams, such as an average residual radial magnetic field penetrating the magnetic shield or a combination of magnetic fields and misalignments of electric elements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB178

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paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 20 August 2021

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MOPAB181

Non-Delivery Time Reduction at MedAustron

extraction, proton, synchrotron, MMI

613

L. Adler, S. Danzinger, F. Farinon, F. Feichtinger, G. Guidoboni, N. Kahn, C. Kurfürst, D.A. Prokopovich, A. Wastl
EBG MedAustron, Wr. Neustadt, Austria
L.C. Penescu
Abstract Landscapes, Montpellier, France

Funding: Funding by the NÖ WIRTSCHAFTS- UND TOURISMUSFONDS under grant number WST3-F-5033232/001-2020.
MedAustron is a cancer treatment center in Austria providing proton and carbon ion beams to three clinical and one non-clinical research beam lines. The slow extraction of particles from the synchrotron follows a third order resonance extraction scheme. Currently, for every change of extraction energy a new spill needs to be generated. Besides the beam-on time of the particle delivery, every spill is also comprised of non-delivery time components e.g. the multiturn injection, acceleration or magnet conditioning. For small tumor target volumes, this non-delivery time is the major contribution to the overall treatment time. A dedicated performance improvement project (supported with a grant from the state of lower Austria) was executed with the goal to reduce these non-delivery times without affecting important clinical beam parameters such as the beam size or penetration depth. The implemented reduction of the non-delivery time >50% could be achieved, resulting in beam-on time reductions for reference treatment plans between 25% (largest proton PTV) and 58% (smallest carbon PTV). Results of commissioning efforts, technical details and the achieved optimizations will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB181

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

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MOPAB182

Automated Synchrotron Lattice Design and Optimisation Using a Multi-Objective Genetic Algorithm

network, lattice, synchrotron, superconducting-magnet

616

X. Zhang, S.L. Sheehy
The University of Melbourne, Melbourne, Victoria, Australia
E. Benedetto
TERA, Novara, Italy
E. Benedetto
CERN, Meyrin, Switzerland

Funding: This work is partially supported by the Australian Government Research Training Program Scholarship.
As part of the Next Ion Medical Machine Study (NIMMS), we present a new method for designing synchrotron lattices. A step-wise approach was used to generate random lattice structures from a set of feedforward neural networks. These lattice designs are optimised by evolving the networks over many iterations with a multi-objective genetic algorithm (MOGA). The final set of solutions represent the most effi- cient and feasible lattices which satisfy the design constraints. It is up to the lattice designer to choose a design that best suits the intended application. The automated algorithm presented here randomly samples from all possible lattice layouts and reaches the global optimum over many iterations. The requirements of an efficient extraction scheme in hadron therapy synchrotrons impose stringent constraints on the lat- tice optical functions. Using this algorithm allows us to find the global optimum that is tailored to these constraints and to fully utilise the flexibilities provided by new technology.

Poster MOPAB182 [6.006 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB182

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paper received ※ 15 May 2021 paper accepted ※ 23 June 2021 issue date ※ 14 August 2021

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MOPAB196

Field tuning of the 1 MeV/n RFQ at KOMAC

rfq, ion-source, quadrupole, solenoid

662

H.-J. Kwon, Y.-S. Cho, J.J. Dang, W.-H. Jung, D.-H. Kim, H.S. Kim, K.H. Kim, S. Lee
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work was supported by the Korea Multi-purpose Accelerator Complex (KOMAC) operation funds through Ministry of Science and ICT (MIST) of Korean Government.
A 1 MeV/n Radio-frequency Quadrupole (RFQ) is under development at Korea Multi-purpose Accelerator Complex (KOMAC), the purposes of which are swift ion beam irradiation and compact neutron source. The RFQ was designed to accelerate ions with mass to charge (A/q) ratio up to 2.5. The designed peak current was 10 mA with 10% duty ratio. The RFQ is four vane structure resonated at 200 MHz. It has total 40 frequency tuners. There are no dipole rods and resonant coupling plate because the mode separation was large enough and the length of the RFQ was only two times of the wavelength. In this paper, the development status and field tuning results of the 1 MeV/n RFQ are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB196

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paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 20 August 2021

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MOPAB198

Study on Magnet Sorting of the CSNS/RCS Dipoles

closed-orbit, MMI, neutron, controls

665

Y. Li, Y.W. An
IHEP, Beijing, People’s Republic of China
Z.P. Li, S.Y. Xu
DNSC, Dongguan, People’s Republic of China

The 1.6GeV rapid cycling synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is a high-power pulsed proton machine aiming for 500kW output beam power. Now, the routine output beam power has been increased to 100kW. However, the horizontal bare orbit in the ring is large (15mm) and the number of correctors is small, which brings great challenges to the ramp-up of beam power. It is found that the bare orbit in AC mode is 3-4mm larger than that in DC mode. The reason is that the AC dipoles field error is larger than DC dipoles field error. Therefore, it is proposed to sort dipoles again according to the AC dipoles field error. In order to reduce the risk of beam commissioning, fewer magnets should to be moved to achieve smaller orbit. The best results of moving two to six magnets were calculated. After sorting, the orbit can be reduced by 3-4mm, which reduces the difficulty of orbit correction.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB198

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paper received ※ 16 May 2021 paper accepted ※ 21 May 2021 issue date ※ 14 August 2021

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MOPAB211

Beam Coupling Impedances of Ferrite-Loaded Cavities: Calculations and Measurements

cavity, impedance, resonance, coupling

696

S.S. Kurennoy, R.C. McCrady
LANL, Los Alamos, New Mexico, USA

We have developed an efficient method of calculating impedances in cavities with dispersive ferrite dampers. The ferrite dispersive properties in the frequency range of interest are fitted in CST, which allows using both wakefield and lossy eigenmode solvers. A simple test cavity with or without ferrite inserts is explored both numerically and experimentally. The resonance frequencies and beam coupling impedances at cavity resonances are calculated with CST to understand the mode structure. The cavity transverse coupling impedances are also measured on a test stand using a two-wire method. We compare results of impedance calculations and measurements for a few different configurations, with and without ferrites, to ensure a complete understanding of the cavity resonances and their damping with ferrite. These results are important to provide adequate damping of undesired transverse modes in induction-linac cells.

Poster MOPAB211 [1.105 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB211

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paper received ※ 10 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021

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MOPAB220

Towards Deterministic Design of MBA-Lattices

lattice, emittance, 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, emittance, 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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MOPAB232

Observation of Polarization-Dependent Changes in Higher-Order Mode Responses as a Function of Transverse Beam Position in Tesla-Type Cavities at FAST

cavity, HOM, electron, cryomodule

756

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

Funding: FNAL supported by U.S. Department of Energy, Office of Science, under contract DE-AC02-07CH11359. SLAC supported by U.S. Department of Energy, Office of Science, under contract DE-AC02-76SF00515.
Higher-order modes (HOMs) in superconducting rf cavities present problems for an electron bunch traversing the cavity in the form of long-range wakefields from previous bunches. These may dilute the emittance of the macropulse average, especially with low emittance beams at facilities such as the European X-ray Free-electron Laser (XFEL) and the upgraded Linac Coherent Light Source (LCLS-II). Here we present observations of HOMs driven by the beam at the Fermilab Accelerator Science and Technology (FAST) facility. The FAST facility features two independent TESLA-type cavities (CC1 and CC2) after a photocathode rf gun followed by an 8-cavity cryomodule. The HOM signals were acquired from cavities using bandpass filters of 1.75 ± 0.15 GHz, 2.5 ± 0.2 GHz, and 3.25 ± 0.2 GHz and recorded using an 8-GHz, 20 GSa/s oscilloscope. The frequency resolution obtained is sufficient to separate polarization components of many of the HOMs. These HOM signals were captured from CC1 and cavities 1 and 8 of the cryomodule for various initial trajectories through the cavities, and we observe correlations between trajectory, HOM signals, and which polarization component of a mode is affected.

Poster MOPAB232 [2.144 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB232

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paper received ※ 20 May 2021 paper accepted ※ 25 May 2021 issue date ※ 10 August 2021

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MOPAB234

Analysis of the Chromatic Vertical Focusing Effect of Dipole Fringe Fields

focusing, simulation, optics, closed-orbit

760

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

Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231
There have been questions regarding the impact of the dipole fringe-field models (used by accelerator codes including ELEGANT and MADX) on vertical chromaticity. Here, we analyze the cause of the disagreement among codes and suggest a correction.

Poster MOPAB234 [0.486 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB234

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paper received ※ 20 May 2021 paper accepted ※ 01 June 2021 issue date ※ 23 August 2021

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MOPAB239

Simulation and Optimization of the Spin Coherence Time of Protons in a Prototype EDM Ring

quadrupole, storage-ring, simulation, polarization

771

M. Vitz, A. Lehrach
FZJ, Jülich, Germany
R. Shankar
INFN-Ferrara, Ferrara, Italy

The matter-antimatter asymmetry might be understood by investigating the EDM (Electric Dipole Moment) of elementary charged particles. A permanent EDM of a subatomic particle violates time-reversal and parity symmetry at the same time and would be, with the currently achievable experimental accuracy, a strong indication for physics beyond the Standard Model. The JEDI-Collaboration (Jülich Electric Dipole moment Investigations) in Jülich is preparing a direct EDM measurement for protons and deuterons: first at the storage ring COSY (COoler SYnchrotron) and later at a dedicated storage ring. A prototype EDM ring is an intermediate step before building the final storage ring to demonstrate sufficient beam lifetime and SCT (Spin Coherence Time) in a pure electrostatic ring as well as in a storage ring with combined electric and magnetic bending elements. In order to study the effect of E-B-deflectors on the orbit and the spin motion, the software library Bmad is used. The first results of the optics and spin simulations, with a focus on the optimization of the SCT, towards the prototype EDM ring will be discussed.

Poster MOPAB239 [0.560 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB239

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paper received ※ 17 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 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, emittance

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

emittance, 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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MOPAB254

Measurement of Horizontal Beam Size Using Sextupole Magnets

sextupole, quadrupole, storage-ring, positron

802

J.A. Crittenden, K.E. Deitrick, H.X. Duan, G.H. Hoffstaetter, V. Khachatryan, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by National Science Foundation award number DMR-1829070.
The quadratic dependence of sextupole fields on position results in a beam-size-dependent kick on a beam traversing a sextupole magnet. A change in sextupole strength changes the closed orbit and the tune of the beam in a storage ring. Measuring both therefore allows conclusions about the beam size in the sextupole. Here we derive the pertinent formula and discuss the applicability to storage rings. In particular we investigate the measurement accuracy that can be achieved at the Cornell High Energy Synchrotron Source. The Cornell Electron-positron Storage Ring underwent a major upgrade in 2018 with the goal of reducing the emittance by a factor of four. A variety of beam size measurement methods have been developed to monitor the positron beam size, including visible synchrotron light and interferometry. We investigate the sensitivity of the sextupole method and compare to other measurement techniques. The design horizontal emittance of the 6-GeV positron beam is about 30 nm-rad with typical beam sizes of about 1 mm, setting the scale for the required accuracy in the beam-size measurement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB254

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paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 01 September 2021

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MOPAB262

First Thoughts on Lattices for a possible Metrology Light Source 2

lattice, emittance, 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

emittance, multipole, MMI, 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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MOPAB269

Three Approaches for Complete Measurement of the Transverse Beam Optics Along the Fermilab Muon Campus Extraction Line

quadrupole, extraction, optics, real-time

854

B.D. Simons, M.J. Syphers
Northern Illinois University, DeKalb, Illinois, USA
D. Stratakis, M.J. Syphers
Fermilab, Batavia, Illinois, USA

Funding: This work was supported through grant DE-SC0020379 with the United States Department of Energy.
Traditionally, the process of measuring the optical parameters of a beamline has employed the use of one of two standard methods, namely the three-screen method or a quadrupole magnet scan. Both require either an area of zero dispersion to perform the measurements or knowledge of the dispersion function and momentum spread beforehand in order to provide accurate results. There is however a third method that can be used to measure the standard optical parameters, the beam parameters, the dispersion function, and the momentum spread simultaneously. This method, aptly named the six-screen method, is an extension of the more standard three-screen method. Utilizing the simulation environment of G4beamline, we simulated the 8 GeV proton beam in the M4 beamline and measured the optical and beam parameters using the two standard approaches. Those results were then used as a reference to check the viability of employing the less standard six-screen method in the M4 line. If shown to be a viable option, the six-screen method could be used to retrieve the dispersion function and momentum spread of the beam without needing to change the energy of the beam.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB269

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paper received ※ 20 May 2021 paper accepted ※ 07 June 2021 issue date ※ 12 August 2021

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MOPAB284

Status of the Dedicated Electron Diagnostic Beamline at AXSIS

electron, diagnostics, MMI, controls

902

H. Dinter, R.W. Aßmann, F. Burkart, M.J. Kellermeier
DESY, Hamburg, Germany
C. Lechner
EuXFEL, Schenefeld, Germany

Funding: The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 609920.
AXSIS (Attosecond X-ray Science: Imaging and Spectroscopy) is a compact, accelerator-driven X-ray source currently under construction at DESY Hamburg. It comprises a THz-powered electron gun and THz-driven linac for all-optical electron extraction and acceleration to several MeV with the goal of providing X-rays generated by inverse Compton scattering for photon science experiments. For the commissioning and characterisation of the THz gun and linac the facility includes a dedicated accelerator testing area, for which an electron diagnostic beamline has been designed and is currently under construction. The challenges imposed by the AXSIS project on the development of the diagnostics beamline are the wide ranges of bunch charge (15 fC to 3 pC) and energy (5 MeV to 20 MeV) expected from the THz-driven accelerator as well as the limited available space of only ca. 2.5 metres length. In this contribution we present an overview of the design and the current commissioning status of the electron diagnostic beamline as well as plans for future steps.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB284

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paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 25 August 2021

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MOPAB304

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

emittance, diagnostics, 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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MOPAB345

Machine Learning with a Hybrid Model for Monitoring of the Protection Systems of the LHC

monitoring, operation, superconducting-magnet, machine-protect

1072

C. Obermair, A. Apollonio, Z. Charifoulline, M. Maciejewski, A.P. Verweij
CERN, Geneva, Switzerland
C. Obermair, F. Pernkopf
TUG, Graz, Austria

The LHC is the world’s largest particle accelerator and uses a complex set of sophisticated and highly reliable machine protection systems to ensure a safe operation with high availability for particle physics production. The data gathered during several years of successful operation allow the use of data-driven methods to assist experts in finding anomalies in the behavior of those protection systems. In this paper, we derive a model that can extend the existing signal monitoring applications for the LHC protection systems with machine learning. Our hybrid model combines an existing threshold-based system with a SVM by using signals, manually validated by experts. Even with a limited amount of data, the SVM learns to integrate the expert knowledge and contributes to a better classification of safety-critical signals. Using this approach, we analyze historical signals of quench heaters, which are an important part of the quench protection system for superconducting magnets. Particularly, it is possible to incorporate expert decisions into the classification process and to improve the failure detection rate of the existing quench heater discharge analysis tool.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB345

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paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 01 September 2021

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MOPAB364

Shielded Pair Method for Cylindrical Surface Resistance Measurement at Cryogenic Temperature

factory, cryogenics, coupling, simulation

1132

K. Brunner, S. Calatroni, F. Caspers
CERN, Geneva, Switzerland
D. Barna
Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary

The shielded pair resonator method was already used in the past at CERN to measure the surface resistivity of the LHC beam screen both at room temperature and cryogenic temperature. We have refined and adapted the measurement to be able to measure other types of beam screens and also to operate in a strong dipolar magnetic field. This is necessary for testing the properties of HTS coated beam screens or the possible effects of coatings and surface treatments for e-cloud suppression. Several calibration runs were done at cryogenic temperatures (4.2 K) measuring the surface resistivity of a copper pipe to identify the precision, stability and reproducibility achievable using this method. This work describes the challenges of the measurement and ways to mitigate them.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB364

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paper received ※ 17 May 2021 paper accepted ※ 22 June 2021 issue date ※ 12 August 2021

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MOPAB374

Creating Exact Multipolar Fields in Accelerating RF Cavities via an Azimuthally Modulated Design

cavity, simulation, quadrupole, collider

1154

L.M. Wroe, S.L. Sheehy
JAI, Oxford, United Kingdom
R. Apsimon
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
M. Dosanjh
CERN, Meyrin, Switzerland
S.L. Sheehy
The University of Melbourne, Melbourne, Victoria, Australia

In this paper, we present a novel method for designing RF structures with specifically tailored multipolar field contributions. This has a range of applications, including the suppression of unwanted multipolar fields or the introduction of wanted terms, such as for quadrupole focusing. In this article, we outline the general design methodology and compare the expected results to 3D CST simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB374

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paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 23 August 2021

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MOPAB384

Nb₃Sn Coating of Twin Axis Cavity for Accelerator Applications

cavity, linac, niobium, SRF

1175

J.K. Tiskumara, S.U. De Silva, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA
J.R. Delayen, H. Park, U. Pudasaini, C.E. Reece
JLab, Newport News, Virginia, USA
G.V. Eremeev
Fermilab, Batavia, Illinois, USA

Funding: Research supported by DOE Office of Science Accelerator Stewardship Program Award DE- SC0019399. Partially authored by Jefferson Science Associates under contract no. DEAC0506OR23177
A Superconducting twin axis cavity consisting of two identical beam pipes that can accelerate and decelerate beams within the same structure has been proposed for the Energy Recovery Linac (ERL) applications. There are two niobium twin axis cavities at JLab fabricated with the intention of later Nb₃Sn coating and now we are progressing to coat them using vapor diffusion method. Nb₃Sn is a potential alternate material for replacing Nb in SRF cavities for better performance and reducing operational costs. Because of advanced geometry, larger surface area, increased number of ports and hard to reach areas of the twin axis cavities, the usual coating approach developed for typical elliptical single-axis cavities must be evaluated and requires to be adjusted. In this contribution, we report the first results from the coating of a twin axis cavity and discuss current challenges with an outlook for the future.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB384

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paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 27 August 2021

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TUXC07

Modified Halbach Magnets for Emerging Accelerator Applications

permanent-magnet, quadrupole, collider, electron

1315

S.J. Brooks
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 original circular Halbach magnet design creates a strong pure multipole field from permanent magnet pieces without intervening iron. This design has been extended recently at the CBETA 4-turn ERL, whose return loop includes combined-function (dipole+quadrupole) Halbach-derived magnets, plus a modular system of tuning shims to improve all 216 magnets’ relative field accuracy to better than 10^-3. This paper describes further modifications of the Halbach design enable a larger range of accelerator applications in the future: (1) open-midplane designs to allow synchrotron radiation in light sources and other high-energy electron rings, ERLs or RLAs to escape. (2) Quadrupole magnets with an oval aperture allow larger gradients than a circular aperture, provided the beam is more extended in one axis than the other, as usual for a quadrupole in a focussing system. These can be used in compact hadron therapy gantries. (3) New collider complexes often require multiple rings for acceleration or top-up, accumulation, collision and cooling. Multi-aperture permanent magnets are possible to cheaply and compactly build ring systems with several stable orbits separated by a few cm.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXC07

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paper received ※ 14 May 2021 paper accepted ※ 08 July 2021 issue date ※ 23 August 2021

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TUPAB008

Progress of the First-Turn Commissioning Simulations for HEPS

simulation, quadrupole, lattice, MMI

1349

B. Wang, Z. Duan, D. Ji, Y. Jiao, Y.L. Zhao
IHEP, Beijing, People’s Republic of China

The High Energy Photon Source (HEPS) is 6 GeV, kilometer-scale, 4th generation storage ring light source. The lattice has an ultralow emittance and strong focusing such that the beam dynamics is very sensitive to the magnet misalignments and other error sources. Getting the first turn and establishing the closed orbit is essential for accelerator commissioning. This paper describes a simulation algorithm for achieving the first turn commission based on the latest HEPS storage ring lattice. We developed a new accelerator toolbox (AT)-based program for automatic optimizing the first turn commissioning. The algorithm and simulation results will be presented in this paper.

Poster TUPAB008 [0.646 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB008

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paper received ※ 14 May 2021 paper accepted ※ 11 June 2021 issue date ※ 28 August 2021

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TUPAB017

Study of Conduction-Cooled Superconducting Quadrupole Magnets Combined with Dipole Correctors for the ILC Main Linac

quadrupole, linac, SRF, cavity

1375

Y. Arimoto, S. Michizono, Y. Morikawa, N. Ohuchi, T. Oki, H. Shimizu, K. Umemori, X. Wang, A. Yamamoto, Y. Yamamoto, Z.G. Zong
KEK, Ibaraki, Japan
V.S. Kashikhin
Fermilab, Batavia, Illinois, USA

A superconducting rf (SRF) cryomodule for International Linear Collider(ILC) Main Linac equips focus/steering magnets. The magnets are "superferric" magnets with four superconducting (SC) race track coils conductively cooled from the cryomodule LHe supply pipe. The quadrupole field gradient and dipole field are 40 T/m and 0.1 T, respectively. The magnet length and iron-pole radius are 1 m and 0.045 m, respectively. It is known that dark current is generated at SRF cavities and accelerated through the following linac string. The dark current reaches and heats the SC magnets. It is estimated that the power deposition in the magnet may reach more than a few watts and temperature of the SC coils may locally reach to critical temperature of NbTi. It is important to make the magnet not reach quench with sufficient conduction cooling. We aim to realize the SC magnet which can stably operate under such condition. We plan to develop test coils made of three types of SC materials, NbTi, Nb₃Sn, and MgB₂ and study thermal characteristics and stability . We will develop a short model magnet, based on the test coil results. Here, we will present the magnet design study and the R&D plan.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB017

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paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 18 August 2021

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TUPAB019

A High-Resolution, Low-Latency, Bunch-by-Bunch Feedback System for Nano-Beam Stabilization

feedback, cavity, kicker, collider

1378

R.L. Ramjiawan, D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich, P. Burrows, G.B. Christian, C. Perry
JAI, Oxford, United Kingdom
D.R. Bett
CERN, Geneva, Switzerland
N. Blaskovic Kraljevic
ESS, Lund, Sweden
G.B. Christian
DLS, Oxfordshire, United Kingdom

A low-latency, bunch-by-bunch feedback system employing high-resolution cavity Beam Position Monitors (BPMs) has been developed and tested at the Accelerator Test Facility (ATF2) at the High Energy Accelerator Research Organization (KEK), Japan. The feedback system was designed to demonstrate nanometer-level vertical stabilization at the focal point of the ATF2 and can be operated using either a single BPM to provide local beam stabilization, or by using two BPMs to stabilize the beam at an intermediate location. The feedback correction is implemented using a stripline kicker and the feedback calculations are performed on a digital board constructed around a Field Programmable Gate Array (FPGA). The feedback performance was tested with trains of two bunches, separated by 280ns, at a charge of ~1nC, where the vertical offset of the first bunch was measured and used to calculate the correction to be applied to the second bunch. The BPMs have been demonstrated to achieve an operational resolution of ~20nm. With the application of single-BPM and two-BPM feedback, beam stabilization of below 50nm and 41nm respectively has been achieved with a latency of 232ns.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB019

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paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 14 August 2021

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TUPAB040

Design Concept for the Second Interaction Region for Electron-Ion Collider

electron, detector, proton, optics

1435

B.R. Gamage, V. Burkert, R. Ent, Y. Furletova, D.W. Higinbotham, A. Hutton, F. Lin, T.J. Michalski, V.S. Morozov, R. Rajput-Ghoshal, D. Romanov, T. Satogata, A. Seryi, A.V. Sy, C. Weiss, M. Wiseman, W. Wittmer, Y. Zhang
JLab, Newport News, Virginia, USA
E.C. Aschenauer, J.S. Berg, A. Jentsch, A. Kiselev, C. Montag, R.B. Palmer, B. Parker, V. Ptitsyn, F.J. Willeke, H. Witte
BNL, Upton, New York, USA
C. Hyde
ODU, Norfolk, Virginia, USA
P. Nadel-Turonski
SBU, Stony Brook, New York, USA

Funding: Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 and Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The possibility of two interaction regions (IRs) is a design requirement for Electron-Ion Collider (EIC). There is also a significant interest from the nuclear physics community to have a 2nd IR with measurement capabilities complementary to those of the 1st IR. While the 2nd IR will be in operation over the entire energy range of ~20GeV to ~140GeV center of mass (CM). The 2nd IR can also provide an acceptance coverage complementary to that of the 1st. In this paper, we present a brief overview and the current progress of the 2nd IR design in terms of the parameters, magnet layout, and beam dynamics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB040

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paper received ※ 24 May 2021 paper accepted ※ 31 August 2021 issue date ※ 30 August 2021

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TUPAB042

Large Radial Shifts in the EIC Hadron Storage Ring

hadron, closed-orbit, electron, insertion

1443

S. Peggs, J.S. Berg, K.A. Drees, X. Gu, C. Liu, H. Lovelace III, Y. Luo, G.J. Marr, A. Marusic, F. Méot, R.J. Michnoff, V. Ptitsyn, G. Robert-Demolaize, M. Valette, S. Verdú-Andrés
BNL, Upton, New York, USA
K.E. Deitrick
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
B.R. Gamage
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Electron Ion Collider will collide hadrons in the Hadron Storage Ring (HSR) with ultra-relativistic electrons in the Electron Storage Ring. The HSR design trajectory includes a large radial shift over a large fraction of its circumference, in order to adjust the hadron path length to synchronize collisions over a broad range of hadron energies. The design trajectory goes on-axis through the magnets, crab cavities and other components in the six HSR Insertion Regions. This paper discusses the issues involved and reports on past and future beam experiments in the Relativistic Heavy Ion Collider, which will be upgraded to become the HSR.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB042

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paper received ※ 18 May 2021 paper accepted ※ 15 June 2021 issue date ※ 21 August 2021

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TUPAB064

Specifications and Performance of a Chicane Magnet for the cERL IR-FEL

FEL, undulator, operation, operational-performance

1512

N. Nakamura, K. Harada, N. Higashi, Y. Honda, R. Kato, C. Mitsuda, S. Nagahashi, T. Obina, H. Sakai, M. Shimada, H. Takaki, O.A. Tanaka
KEK, Ibaraki, Japan
Y. Lu
Sokendai, 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 IR-FEL was constructed in the Compact ERL (cERL) at KEK from October 2019 to May 2020 for the purpose of developing high-power mid-infrared lasers for high-efficiency laser processing utilizing molecular vibrational absorption. The chicane magnet was newly installed between two IR-FEL undulators in the cERL in order to increase the FEL gain and pulse energy by converting the energy modulation to the density modulation in an electron bunch. It consists of three dipole magnets with laminated yokes made of 0.1-mm-thick permalloy sheets and the coil currents of the three magnets are independently controlled by three power supplies with the maximum current of 10 A. The maximum closed orbit bump made by the chicane magnetic field has the longitudinal dispersion(R56) of -6 mm. The coil-current ratio of the three dipole magnets was tuned after installation to make its orbit bumps closed and then the chicane magnet was used in the FEL operation. We present specifications and operational performance of the chicane magnet.

Poster TUPAB064 [4.053 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB064

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paper received ※ 18 May 2021 paper accepted ※ 25 May 2021 issue date ※ 25 August 2021

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TUPAB087

Full Characterization of the Bunch-Compressor Dipoles for FLUTE

electron, linac, HOM, controls

1585

Y. Nie, A. Bernhard, E. Bründermann, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, Y. Tong
KIT, Karlsruhe, Germany

Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research).
The Ferninfrarot Linac- Und Test-Experiment (FLUTE) is a KIT-operated linac-based test facility for accelerator research and development as well as a compact, ultra-broadband and short-pulse terahertz (THz) source. As a key component of FLUTE, the bunch compressor (chicane) consisting of four specially designed dipoles will be used to compress the 40-50 MeV electron bunches after the linac down to single fs bunch length. The maximum vertical magnetic field of the dipoles reach 0.22 T, with an effective length of 200 mm. The good field region is ±40 mm and ±10.5 mm in the horizontal and vertical direction, respectively. The latest measurement results of the dipoles in terms of field homogeneity, excitation and field reproducibility within the good field regions will be reported, which meet the predefined specifications. The measured 3D magnetic field distributions have been used to perform beam dynamics simulations of the bunch compressor. Effects of the real field properties on the beam dynamics, which are different from that of the ASTRA built-in dipole field, will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB087

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paper received ※ 10 May 2021 paper accepted ※ 27 May 2021 issue date ※ 01 September 2021

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TUPAB102

A New 2nd Bunch Compression Chicane for the FLASH2020+ Project

quadrupole, vacuum, focusing, FEL

1618

M. Vogt, J. Zemella
DESY, Hamburg, Germany

The first stage of the FLASH2020+ project is an upgrade of the FLASH injector beamline. Within this framework, the 2nd bunch compression chicane (BCC) will be completely redesigned. The old S-chicane will be replaced with a new C-chicane which is 3.5m shorter thereby generating space a new section for re-matching the beam from the injector into the linac. The new BCC will be equipped with quad/skew-quad units in both legs of the chicane to compensate correlations of the transverse degrees of freedom with the longitudinal ones. Since quadrupoles tend to have a circular bore, the chicane is designed with movable round vacuum chambers and movable dipoles for maintaining full flexibility in choosing the compression parameters. This article describes the technical details and introduces a thin-lens model of BCCs which allows analytical estimates on the effects of powering the quad/skew-quad units on optics parameters as well as estimates on the required strengths of these magnets in order to remove correlations of the magnitudes typically observed at FLASH.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB102

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paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 29 August 2021

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TUPAB175

ESSnuSB Linac and Transfer Line: Lattice Design and Error Studies

linac, lattice, proton, DTL

1805

N. Blaskovic Kraljevic, M. Eshraqi, B.T. Folsom
ESS, Lund, Sweden

Funding: ESSnuSB has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 777419.
The ESS neutrino superbeam (ESSnuSB) project is being studied as an upgrade to the European Spallation Source (ESS). This proposed upgrade consists of adding an H⁻ source to the existing beamline in order to send H⁻ pulses in between proton pulses, effectively doubling the beam power from 5 MW to 10 MW. In this contribution, we present the 2.5 GeV linear accelerator (linac) lattice and the design of the transfer line from the linac to the accumulator ring, where pulses would be stacked to achieve short proton pulses of high intensity. The results of error studies, quantifying the effect of accelerator imperfections and H⁻ ion stripping losses on the beam transport through the linac and transfer line, are also presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB175

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paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 31 August 2021

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TUPAB217

Effect of Undulators on Transverse Resonant Island Orbits

undulator, operation, diagnostics, optics

1927

E.C.M. Rial, J. Bahrdt, P. Goslawski, A. Meseck, M. Ries, M. Scheer
HZB, Berlin, Germany

For one week in October 2020, BESSY II offered a Two Orbit mode to users for the first time*. In this Two Orbit mode, the existence of transverse resonant island buckets** are exploited to store a second beam in the storage ring as an ’island orbit’, away from the primary beam axis. This mode was offered with free range of motion of the 12 out of vacuum undulators installed at the BESSY II ring. Diagnostics of the island orbit were limited to a single camera monitoring bending magnet radiation from a single dipole. A significant motion of the island orbit was observed on this diagnostic and correlated with undulator motion. This observation is reported, and simulations presented to demonstrate how this motion could arise. Correction schemes are suggested and discussed.
*Two Orbit - a report on the first scheduled week of TRIBs user operation at BESSY II, M. Ries et al, these proceedings
**Proc. IPAC 2016, Busan, S Korea, paper THPMR017, p. 3427

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB217

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 22 August 2021

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TUPAB218

Fully Covariant Two-Particle Space-Charge Dynamics Using the Liénard-Wiechert Potentials

electromagnetic-fields, electron, space-charge, FEL

1931

B.T. Folsom, E. Laface
ESS, Lund, Sweden

Space charge models typically assume instantaneous propagation of the electromagnetic fields between particles in a bunch, describing forces in the frame of the reference particle. In this paper, we construct a space-charge tracking code from the retarded Liénard-Wiechert potentials, which are covariant by design, in a Lagrangian formulation. Such potentials are manipulated with covariant derivatives to produce the necessary equations of motion that will be solved in a test system of two particles at various relative energies. Magnetic dipole moment dynamics are also evaluated where applicable.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB218

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

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TUPAB231

Cooling of an Annular Beam by Using Nonlinear Effects

resonance, emittance, 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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TUPAB237

Symplectic Tracking Through Field Maps

quadrupole, cavity, ion-source, radio-frequency

1992

S.D. Webb
RadiaSoft LLC, Boulder, Colorado, USA
B.T. Folsom, E. Laface, R. Miyamoto
ESS, Lund, Sweden

For many applications, it is necessary to track particles using field maps, instead of an analytic representation of the fields which is typically not available. These field maps come about while designing elements such as realistic magnets or radiofrequency cavities, and represent the field geometry on a mesh in space. However, simple interpolation of the fields from the field maps does not guarantee that the resulting tracking scheme satisfies the symplectic condition. Here we present a general method to decompose the field-map potential in the sum of interpolating functions that produces, by construction, a symplectic integrator.

Poster TUPAB237 [0.307 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB237

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

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TUPAB258

Impact of Coherent Beam-Beam Interaction on the Landau Damping of the Transverse Coupled-Bunch Instability

electron, damping, coupling, proton

2062

R. Li
JLab, Newport News, Virginia, USA
M. Blaskiewicz
BNL, Upton, New York, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
In the EIC design, at high average-current operation, the transverse coupled-bunch instability (TCBI) induced by the long-range transverse resistive-wall wakefield in the electron storage ring (eSR) has a fast growth rate and requires efficient mitigation. A natural mitigation mechanism is provided by the beam-beam interaction at the interaction point (IP), which gives a strong Landau damping for the TCBI in the eSR. In this study, using a simplified simulation model, we investigate how this Landau damping from the beam-beam interaction behaves when the coherent beam-beam interaction at IP is considered. Our method and results will be presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB258

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paper received ※ 21 June 2021 paper accepted ※ 01 July 2021 issue date ※ 25 August 2021

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TUPAB260

A Beam Screen to Prepare the RHIC Vacuum Chamber for EIC Hadron Beams: Conceptual Design and Requirements

vacuum, electron, hadron, collider

2066

S. Verdú-Andrés, M. Blaskiewicz, J.M. Brennan, X. Gu, R.C. Gupta, A. Hershcovitch, M. Mapes, G.T. McIntyre, J.F. Muratore, S.K. Nayak, S. Peggs, V. Ptitsyn, R. Than, J.E. Tuozzolo, D. Weiss
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 Electon Ion Collider (EIC) hadron ring will use the existing Relativistic Heavy Ion Collider storage rings, including the superconducting magnet arcs. The vacuum chambers in the superconducting magnets and the cold mass interconnects were not designed for EIC beams and so must be updated to reduce its resistive-wall heating and to suppress electron clouds. To do so without compromising the EIC luminosity goal, a stainless steel beam screen with co-laminated copper and a thin layer of amorphous carbon will be installed. This paper describes the main requirements that our solution for the hadron ring vacuum chamber needs to satisfy, including impedance, aperture limitations, vacuum, thermal and structural stability, mechanical design, installation and operation. The conceptual design of the beam screen currently under development is introduced.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB260

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

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TUPAB319

SNS Credited Beam Power Limit System Preliminary Design

PLC, timing, target, controls

2242

C. Deibele
ORNL, Oak Ridge, Tennessee, USA
K.L. Mahoney
ORNL RAD, Oak Ridge, Tennessee, USA

The Controls Group at the Spallation Neutron Source (SNS) is designing a programmable signal processor based credited safety control that calculates pulsed beam power based on beam kinetic energy and charge. The system must reliably shut off the beam if the average power exceeds 2.145 MW averaged over 60 seconds. This paper discusses architecture and design choices needed to develop the system under the auspices of a programmable radiation-safety credit control.

Poster TUPAB319 [1.925 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB319

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paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 25 August 2021

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TUPAB359

Magnetic Field Measurement and Beam Performance Test of Ceramics Chamber with Integrated Pulsed Magnet at KEK-PF

vacuum, experiment, survey, kicker

2352

Y. Lu
Sokendai, Ibaraki, Japan
K. Harada, Y. Kobayashi, C. Mitsuda, S. Nagahashi, T. Nogami, T. Obina, R. Takai, H. Takaki, T. Uchiyama, A. Ueda
KEK, Ibaraki, Japan

An air-core magnet named Ceramics Chamber with integrated Pulsed Magnet(CCiPM) is being developed at the photon factory of KEK(KEK-PF), which will have several applications for the future light source. One prototype has been developed as a dipole kicker, whose bore is only 30mm. Due to the type and structure, it’s expected to have strong magnetic field and high repetition rate. After finishing the offline measurement of magnetic field and evaluation of vacuum tightness, the CCiPM was installed in the beam transport-dump line of PF to have an online beam performance and durability test. The results of the magnetic field measurement and beam performance test will be reviewed.

Poster TUPAB359 [1.164 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB359

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 16 August 2021

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TUPAB361

Study and Design of a Fast Switching Magnet for the MYRRHA Project

linac, proton, optics, beam-transport

2356

E. Froidefond, F. Bouly, P.-O. Dumont
LPSC, Grenoble Cedex, France
D. Vandeplassche
SCK•CEN, Mol, Belgium

Funding: Work supported by SCK•CEN, CNRS/IN2P3, Univ. Grenoble Alpes.
The MYRRHA project aims at building an Accelerator Driven System demonstrator, which consists of two injectors and a superconducting linac. The proton beam from the first injector accelerated up to 17 MeV goes to the linac (600 MeV) through a Medium Energy Beam Transfer line (MEBT). Whereas in the meantime, the beam from the second injector is sent to a beam dump. In case of failure in the first injector, the beam of the awaiting injector is sent to the linac. A switching magnet located at the junction of the two injection lines performs this beam switch in less than 1.5 seconds. A magnetic design and a mechanical structure of this magnet proposed to the MYRRHA project are presented.
*emmanuel.froidefond@lpsc.in2p3.fr

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB361

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

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TUPAB364

Dipole CR FAIR

HOM, simulation, storage-ring, experiment

2367

K.K. Riabchenko, A.Yu. Pakhomov, T.V. Rybitskaya, A.A. Starostenko, A.S. Tsyganov, K.V. Zhiliaev
BINP SB RAS, Novosibirsk, Russia

The design of CR dipole magnets (24+2 pieces) for the FAIR project in Germany began in 2014 at BINP. CR is a special storage ring where the main emphasis is placed on efficient stochastic pre-cooling of intense beams of stable ions, rare isotopes, or antiprotons. This type of magnet is an iron-based electromagnet with a straight pole, sector form is realized by cutting ends. The maximum field value is 1.6 T. The integrated over the length of the magnet field quality as a function of radius is dBl/Bl = ± 10^-4 with 190 mm good field region as required from the beam dynamics simulations. This challenging field quality is necessary mainly for precise experiments with ion beam in the ISO regime. Below 1.6 T the value dBl/Bl can be higher with a linear approximation up to ± 2.5× 10^-4 at the field level of 0.8 T. The first prototype has been manufactured at the end of 2020. Here we describe features of the dipole, 3D calculations, and measurements of the magnetic field.

Poster TUPAB364 [1.587 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB364

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paper received ※ 09 May 2021 paper accepted ※ 31 May 2021 issue date ※ 28 August 2021

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TUPAB368

Design of the Longitudinal Gradient Dipole Magnets for HALF

permanent-magnet, storage-ring, lattice, emittance

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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TUPAB369

A Fast Non-Linear Model for the EBS Combined Sextupole-Corrector Magnets

sextupole, SRF, multipole, quadrupole

2381

G. Le Bec
ESRF, Grenoble, France

Corrector are often integrated in higher order accelerator magnets. In the new ESRF-EBS storage ring, the sextupoles include additional windings allowing for dipole and skew quadrupole corrections. The accurate modelization of such magnets is not as trivial as it may appear, due to their non-linearities and to the crosstalk between their channels. Changing any corrector current induce non-linear errors in the other corrector channels and in the main sextupole strength, making difficult the trimming of the magnets. A model based on a non-linear excitation curve and quadratic contributions from corrector currents was developed. This model is very fast and was included in the accelerator control system to compute the corrector currents in real-time. It was tested against 3D magnetic simulations and magnetic measurements and compared to a simpler matrix-based model.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB369

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paper received ※ 17 May 2021 paper accepted ※ 31 August 2021 issue date ※ 22 August 2021

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TUPAB370

Development of Long Coil Dynamic Magnetic Field Measurement System for Dipole Magnets of HEPS Booster

booster, interface, storage-ring, injection

2384

Y.Q. Liu, C.D. Deng, W. Kang, L. Li, S. Li, X. Wu, Y.W. Wu, J.X. Zhou
IHEP, Beijing, People’s Republic of China
C.D. Deng, Y.W. Wu
DNSC, Dongguan, People’s Republic of China

A magnetic field measurement system for dipole magnets of High Energy Photon Source Booster is designed and developed. The system uses the long coil upflow method to measure the dynamic integral field of the magnet, and the long coil transverse-translation method to measure the integral field distribution error of the magnet. In this paper, the design and implementation of the magnetic measuring system are introduced in detail, and the magnetic field measurement results of the prototype magnet are shown. The measurement results show that the repeatability of the dynamic integral field measurement system is about 2 in 10,000, and the repeatability of the uniform distribution of the integral field is better than 1 in 10,000, which meets the test requirements of the discrete integral field of bulk magnets ±1 parts per thousand and the uniformity of the integral field ±5×10-4@6GeV and ±1×10^-3 @0.5GeV.

Poster TUPAB370 [1.475 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB370

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paper received ※ 16 May 2021 paper accepted ※ 16 June 2021 issue date ※ 17 August 2021

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TUPAB378

Superconducting Dipole Magnets for the SIS100 Synchrotron

synchrotron, multipole, operation, simulation

2401

F. Kaether, P. Aguar Bartolome, A. Bleile, G. Golluccio, J. Ketter, P. Kosek, F. Kurian, V. Marusov, J.P. Meier, S.S. Mohite, C. Roux, P.J. Spiller, K. Sugita, A. Szwangruber, P.B. Szwangruber, A. Warth, H.G. Weiss
GSI, Darmstadt, Germany

The Facility for Antiproton and Ion Research (FAIR) is currently under construction at GSI Darmstadt, Germany. For its main accelarator, the SIS100 synchrotron, 110 superconducting dipole magnets has been produced and extensively tested. The fast-ramped Nuclotron-type superferric dipoles were manufactured with high effort regarding a precise magnetic field which could be proven by magnetic field measurements with high accuracy. Stable operation conditions at 4.5 K were achieved including an excellent quench behaviour and precise geometrical and electrical properties. An overview on design, production, operation, tests and measurement results will be given.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB378

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 10 August 2021

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TUPAB379

Superconducting Magnets for Super-FRS: Production and Testing Status

quadrupole, superconductivity, sextupole, superconducting-magnet

2405

H. Müller, A. Chiuchiolo, E.J. Cho, G. Golluccio, F. Greiner, P. Kosek, M. Michels, C. Roux, K. Sugita, V.V. Velonas, M. Winkler
GSI, Darmstadt, Germany
H. Allain, A. Madur
CEA-IRFU, Gif-sur-Yvette, France
A. Borceto, G. Drago, G. Valesi
ASG, Genova, Italy
M. Garcia Escudero, M. Lopez, J. Lucas
Elytt Energy, Madrid, Spain
G. Riddone, S. Russenschuck
CERN, Geneva, Switzerland

The Super FRS is a two-stage in flight separator to be built next to the site of GSI, Darmstadt, Germany as part of FAIR (Facility for Anti-proton and Ion Research). Its three branches allow to carry out a wide variety of experiments. Due to the large acceptance needed, the magnets of the Super-FRS require a large aperture and therefore only a superconducting solution is feasible. A superferric design was chosen in which the magnetic field is shaped by an iron yoke. For the dipole magnets only the superconducting coils are in a cryostat. These magnets are manufactured by Elytt Energy (Spain). The multiplets, assemblies of quadrupoles and higher order multipole magnets, are completely immersed in a liquid Helium bath. They are being built at ASG (Italy). The first of two first of series multiplets, a short assembly containing 2 magnets, was tested at a dedicated test facility at CERN (Switzerland). The 2nd FoS multiplet, containing 9 magnets, and the FoS dipole will be tested soon. Series production of the multiplets has started. In this paper we will present the status of production and testing of the different superconducting magnets for Super-FRS.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB379

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paper received ※ 19 May 2021 paper accepted ※ 31 August 2021 issue date ※ 16 August 2021

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TUPAB381

Thermal Analysis of the RHIC Arc Dipole Magnet Cold Mass with the EIC Beam Screen

vacuum, electron, hadron, cryogenics

2413

S.K. Nayak, M. Anerella, M. Blaskiewicz, J.M. Brennan, R.C. Gupta, M. Mapes, G.T. McIntyre, S. Peggs, R. Than, J.E. Tuozzolo, S. Verdú-Andrés, D. Weiss
BNL, Upton, New York, USA

Funding: Funding agency Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The EIC will make use of the existing RHIC storage rings with their superconducting (SC) magnet arcs. A stainless-steel beam screen with co-laminated copper and a thin amorphous carbon (aC) film on the inner surface will be installed in the beam pipe of the SC magnets. The copper will reduce the beam-induced resistive-wall (RW) heating from operation with the higher intensity EIC beams, that if not addressed would make the magnets quench. Limiting the RW heating is also important to achieve an adequately low vacuum level. The aC coating will reduce secondary electron yield which could also cause heating and limit intensity. Among all the RHIC SC magnets, the arc dipoles present the biggest challenge to the design and installation of beam screens. The arc dipoles, which make up for 78% (2.5 km) length of all SC magnets in RHIC, expect the largest RW heating due to their smallest aperture. These magnets are also the longest (9.45 m each), thus experiencing the largest temperature rise over their length, and have a large sagitta (48.5 mm) that increases the difficulty to install the beam screen in place. This paper presents a detailed thermal analysis of the magnet-screen system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB381

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paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 23 August 2021

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TUPAB386

Design Study of the Nb₃Sn Cos-Theta Dipole Model for FCC-hh

superconductivity, collider, FEL, FEM

2421

R.U. Valente
La Sapienza University of Rome, Rome, Italy
S. Burioli, P. Fabbricatore, S. Farinon, F. Levi, R. Musenich, A. Pampaloni
INFN Genova, Genova, Italy
E. De Matteis, M. Statera
INFN/LASA, Segrate (MI), Italy
F. Lackner, D. Tommasini
CERN, Meyrin, Switzerland
S. Mariotto, M. Prioli
INFN-Milano, Milano, Italy
M. Sorbi
Universita’ degli Studi di Milano & INFN, Segrate, Italy

In the context of the Future Circular Collider hadron-hadron (FCC-hh) R&D program, the Italian Institute of Nuclear Physics (INFN), in collaboration with CERN, is responsible for designing and constructing the Falcon Dipole (Future Accelerator post-LHC Costheta Optimized Nb₃Sn Dipole), which is an important step towards the construction of High Field Nb₃Sn magnets for a post LHC collider. The magnet is a short model with one aperture of 50 mm and the target bore field is 12 T (14 T ’ultimate’ field). The dipole is pre-loaded with the Bladder&Key technique to minimize the stress on the coils at room temperature, which are prone to degradation because of the Nb₃Sn cable strain-sensitivity. The electro-mechanical 2D design is focused on the performance, the field quality and the quench protection, with emphasis to the stresses on the the conductor. The Falcon Dipole has been modelled in a 3D FEM to determine the peak field distribution and the influence of the coil ends on the field quality.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB386

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

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WEPAB003

Overview of the Magnets Required for the Interaction Region of the Electron-Ion Collider (EIC)

electron, hadron, quadrupole, collider

2578

H. Witte, K. Amm, M. Anerella, J. Avronsart, A. Ben Yahia, J.P. Cozzolino, R.C. Gupta, H.M. Hocker, P. Kovach, G.J. Mahler, A. Marone, R.B. Palmer, B. Parker, S.R. Plate, C.E. Runyan, J. Schmalzle
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 planned electron-ion collider (EIC) at Brookhaven National Laboratory (BNL) is designed to deliver a peak luminosity of 1x10³⁴ cm^-2 s^-1. This paper presents an overview of the magnets required for the interaction region of the BNL EIC. To reduce risk and cost the IR is designed to employ conventional NbTi superconducting magnets. In the forward direction the magnets for the hadrons are required to pass a large neutron cone and particles with a transverse momentum of up to 1.3 GeV/c, which leads to large aperture requirements. In the rear direction the synchrotron radiation fan produced by the electron beam must not hit the magnet apertures, which determines their aperture. For the forward direction a mostly interleaved scheme is used for the optics, whereas for the rear side 2-in-1 magnets are employed. We present an overview of the EIC IR magnet design including the forward spectrometer magnet B0.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB003

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paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 29 August 2021

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WEPAB026

Optics Measurements and Correction Plans for the HL-LHC

coupling, optics, luminosity, dynamic-aperture

2656

T.H.B. Persson, X. Buffat, F.S. Carlier, R. De Maria, J. Dilly, E. Fol, D. Gamba, H. Garcia Morales, A. García-Tabarés Valdivieso, M. Giovannozzi, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, P.K. Skowroński, F. Soubelet, R. Tomás García, F.F. Van der Veken, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt
CERN, Geneva, Switzerland
J.M. Coello de Portugal
PSI, Villigen PSI, Switzerland

The High Luminosity LHC (HL-LHC) will require stringent optics correction to operate safely and deliver the design luminosity to the experiments. In order to achieve this, several new methods for optics correction have been developed. In this article, we outline some of these methods and we describe the envisioned strategy of how to use them in order to reach the challenging requirements of the HL-LHC physics program.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB026

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paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021

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WEPAB027

Optics Correction Strategy for Run 3 of the LHC

coupling, optics, MMI, quadrupole

2660

T.H.B. Persson, R. De Maria, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, E.J. Høydalsvik, J. Keintzel, M. Le Garrec, E.H. Maclean, L. Malina, F. Soubelet, R. Tomás García, A. Wegscheider, D.W. Wolf, L. van Riesen-Haupt
CERN, Geneva, Switzerland
J.F. Cardona
UNAL, Bogota D.C, Colombia

The Run 3 of the LHC will continue to provide new challenges for optics corrections. In order to succeed and go beyond what was achieved previously, several new methods to measure and correct the optics have been developed. In this article we describe these methods and outline the plans for the optics commissioning in 2022.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB027

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paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021

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WEPAB032

Studies of the Short-Range Wakefields for the Electron Storage Ring in the Electron Ion Collider

simulation, electron, vacuum, wakefield

2675

G. Wang, M. Blaskiewicz, A. Blednykh, M.P. Sangroula
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.
During the estimates of impedance budget for the Electron Storage Ring (ESR) of Electron-Ion Collider (EIC), various codes, including GdfidL, CST and ECHO3D, have been used to calculate the short-range wake-fields due to the vacuum components. The ECHO 3D code demonstrates more reliable results for the tapered type of structures rather than the GdfidL code, where the stepsize needs to be dramatically decreased to achieve a high-performance calculation. Impedance of the following components are discussed and compared in details: Interaction Region (IR) chamber, bellows, and synchrotron radiation mask (flange absorber).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB032

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paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 24 August 2021

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WEPAB089

Conceptual Design of Booster Synchrotron for Siam Photon Source II

booster, synchrotron, lattice, focusing

2795

S. Krainara, S. Klinkhieo, P. Klysubun, T. Pulampong, P. Sudmuang
SLRI, Nakhon Ratchasima, Thailand

Funding: Synchrotron Light Research Institute (Public organization)
A project on a 3.0 GeV Siam Photon Source II (SPS-II) has been started. The storage ring of SPS-II was designed to obtain an electron beam with a low-emittance below 1 nm-rad. The SPS-II injector mainly consists of a 150 MeV linac and a full-energy booster synchrotron. The booster synchrotron will be installed in the same tunnel as the storage ring, with a total circumference of 304.829 meters. The proposed lattice of the booster contains 40 modified FODO cells with combined function magnets. This lattice achieves a small beam emittance less than 10 nm-rad at 3 GeV, which can provide a high injection efficiency for top-up operation. The conceptual design for SPS-II booster synchrotron is presented in this work.

Poster WEPAB089 [1.187 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB089

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paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 24 August 2021

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WEPAB150

Monotron Beam Break Up Instability Analysis

HOM, cavity, klystron, resonance

2968

V. Volkov, V.M. Petrov
BINP SB RAS, Novosibirsk, Russia

New features of monotron beam break up (BBU) instability such as the typing of high order monopole modes (HOMs)in each cavity by two classes one of them are stable and other ones are unstable, HOM effective quality factor depending on average beam current, and normalized invariable threshold current individually characterizes each HOM are investigated in this article in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB150

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 31 August 2021

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WEPAB151

Regenerative Beam Break Up Instability Analysis

cavity, HOM, linac, experiment

2971

V. Volkov, V.M. Petrov
BINP SB RAS, Novosibirsk, Russia

New features of regenerative beam break up (BBU) instability such as the typing of high order dipole modes (HOMs)in each cavity by two classes, one of them are stable and other ones are unstable, HOM effective quality factor depending on average beam current, and normalized invariable threshold current individually characterizes each HOM are investigated in this article in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB151

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paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 01 September 2021

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WEPAB180

Design and Beam Dynamics Studies of a Novel Compact Recoil Separator Ring for Nuclear Research with Radioactive Beams

ISOL, optics, quadrupole, operation

3031

J. Resta-López
UVEG, Burjasot (Valencia), Spain
A.P. Foussat, G. Kirby
CERN, Geneva, Switzerland
I. Martel
University of Huelva, Huelva, Spain
V. Rodin
The University of Liverpool, Liverpool, United Kingdom
V. Rodin
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was supported by the Generalitat Valenciana under grant agreement CIDEGENT/2019/058
The recent development of radioactive beam facilities has significantly expanded the capabilities for investigating the structure of the atomic nucleus and the nuclear interaction. For instance, the HIE-ISOLDE facility at CERN delivers presently the largest range of low-energy radioactive beam available worldwide. This energy range is ideal for the study of nuclear structure, low-energy dynamics and astrophysics by using nucleon transfer, Coulomb excitation and deep inelastic reactions. All these studies require an efficient and high-resolution recoil separator for the clear identification of medium and large mass reaction fragments. To meet these needs, we propose a versatile recoil separator for radioisotopes based on a compact storage ring, the Isolde Superconducting Recoil Separator (ISRS) formed of superconducting combined-function nested magnets with both, bending and focusing/defocusing functions. The ISRS is designed to operate in high momentum acceptance and isochronous modes. In this paper, we present the optics design and detailed beam dynamics studies for the performance characterisation.

Poster WEPAB180 [3.619 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB180

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 31 August 2021

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WEPAB188

New Method to Search for Axion-Like Particles Demonstrated with Polarized Beam at the COSY Storage Ring

polarization, resonance, storage-ring, experiment

3057

S. Karanth
Jagiellonian University, Kraków, Poland

The axion was originally proposed to explain the small size of CP violation in quantum chromodynamics. It might be a candidate for dark matter in the universe. Axions or axion-like particles (ALPs) when coupled to gluons induce an oscillating Electric Dipole Moment (EDM) along the nucleon’s spin direction. At the Cooler Synchrotron (COSY) in Jülich, this principle was used to perform a first test experiment to search for ALPs using an in-plane polarized deuteron beam. If the spin precession frequency equals the EDM oscillation frequency, a resonance occurs that accumulates the rotation of the polarization out of the ring plane. Since the axion frequency is unknown, the beam momentum was ramped to search for a vertical polarization jump that would occur when the resonance is crossed. At COSY, four beam bunches with different polarization directions were used to make sure that no resonance was missed because of the unknown relative phase between the polarization precession and the EDM oscillations. We scanned a frequency window of about a 1-kHz width around the spin precession frequency of 121 kHz. This talk will describe the experiment and show preliminary results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB188

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 31 August 2021

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WEPAB211

Lattice Design of the Beam Transfer Line (BTL) from PIP-II LINAC to the Booster at Fermilab

booster, lattice, septum, power-supply

3120

M. Xiao
Fermilab, Batavia, Illinois, USA

PIP-II beam transfer line (BTL) to transport the beam from PIP-II Linac to the Booster ring at Fermilab. The latest design eliminates rolling the dipoles in the beam line to cross over the Tevatron tunnel. Also re-designed is the lattice in the region of the Booster Injection to meet the request of the civil construction needs and accommodate the constrains of the Booster injection request. A beam line to the beam absorber (BAL) is designed based on the request from the results of Mars simulations and ANASYS calculation of the absorber. Simulations with dipole and quadrupole field errors for the Beam Transport Line (BTL) to the Booster, which provides the specifications for all the magnets and Power supplies, will be presented too.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB211

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paper received ※ 20 May 2021 paper accepted ※ 08 July 2021 issue date ※ 31 August 2021

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WEPAB238

Modeling Short Range Wakefield Effects in a High Gradient Linac

wakefield, linac, alignment, space-charge

3185

F. Bosco, M. Carillo, L. Faillace, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
M. Behtouei, L. Faillace, A. Giribono, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
F. Bosco, M. Migliorati
INFN-Roma1, Rome, Italy
L. Giuliano, A. Mostacci, L. Palumbo
INFN-Roma, Roma, Italy
J.B. Rosenzweig
UCLA, Los Angeles, California, USA

Funding: This work is supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
The interaction of charged beams with the surrounding accelerating structures requires a thorough investigation due to potential negative effects on the phase space quality. Indeed, the wakefields acting back on the beam are responsible for emittance dilution and instabilities, such as the beam break-up, which limit the performances of electron-based radiation sources and linear colliders. Here we introduce a new tracking code which is meant to investigate the effects of short-range transverse wakefields in linear accelerators. The tracking is based on quasi-analytical models for the beam dynamics which, in addition to the basic optics specified by the applied fields, include dipole wakefield forces and a simple approach to account for space-charge effects. Such features provide a reliable tool which easily allows to inspect the performances of a linac. To validate the model, a parallel analysis for a reference case is performed with well-known beam dynamics codes, and comparisons are shown. As an illustrative application, we discuss a study on alignment tolerances evaluating the emittance growth induced by misaligned accelerating sections.

Poster WEPAB238 [1.747 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB238

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paper received ※ 18 May 2021 paper accepted ※ 07 July 2021 issue date ※ 01 September 2021

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WEPAB245

A Possible Modification of Ceramic Chambers in the Injection Area at the RCS in J-PARC

impedance, simulation, injection, proton

3205

Y. Shobuda, K. Horino, J. Kamiya, K. Kotoku, T. Takayanagi, T. Ueno, T. Yanagibashi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The J-PARC RCS is composed of ceramic chambers covered over copper stripes to suppress the eddy current on the chamber. The inductance, comprising the copper stripes and flanges, in combination with the capacitors makes an LCR electric circuit with the chamber and can cause field modulation in the chamber. Though most chambers are not harmful at the RCS, the chambers at the injection area excite beam losses, because a trapezoid field pattern is excited to accumulate LINAC beam during the injection period. In this report, we consider several types of ceramic chambers to suppress the field modulation. One type is a ceramic chamber covered over copper stripes in parallel with damping resistors. Another is that covered over spiral copper stripes with only capacitors.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB245

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

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WEPAB249

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

space-charge, vacuum, emittance, 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.

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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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WEPAB302

COSY Machine-Model Optimization

operation, simulation, betatron, optics

3375

I. Bekman, J.H. Hetzel
FZJ, Jülich, Germany

Funding: Helmholtz Association
Successful operation of a particle accelerator requires accompanying model calculations. The model helps in understanding the machine and predicts the impact of a change in the settings (e.g. current of magnetic elements). For the COoler SYnchrotron (COSY) at Research Center Jülich the accelerator simulation software MAD-X is used to model the machine. The model parameters are steadily being improved based on various manual adjustments and analytical studies, however are hardly optimized all at once. This can be improved with machine learning methods. The model is used to predict measurable quantities, like Orbit Response Matrix (ORM) or betatron tunes. Several observables for different particle energies have been measured recently and the corresponding machine settings are available. We describe the effort to improve the agreement between measured and calculated ORMs and hence improve the agreement between model and (real) machine and report on the optimization using a multivariate algorithm (e.g. genetic algorithm). This facilitates the setup of COSY and will allow to perform high precision experiments e.g. a measurement of an electric dipole moment of deuterons at COSY.

Poster WEPAB302 [1.905 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB302

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paper received ※ 14 May 2021 paper accepted ※ 28 July 2021 issue date ※ 20 August 2021

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WEPAB339

Beam-Induced Surface Modification of the LHC Beam Screens: The Reason for the High Heat Load in Some LHC Arcs?

electron, cryogenics, hadron, ECR

3479

V. Petit, P. Chiggiato, M. Himmerlich, G. Iadarola, H. Neupert, M. Taborelli, D.A. Zanin
CERN, Geneva, Switzerland

All over Run 2, the LHC beam-induced heat load exhibited a wide scattering along the ring. Studies ascribed the heat source to electron cloud build-up, indicating an unexpectedly high Secondary Electron Yield (SEY) of the beam screen surface in some LHC regions. During the Long Shutdown 2, the beam screens of a low and a high heat load dipole were extracted. Their inner copper surface was analysed in the laboratory to compare their SEY and surface composition. While findings on the low heat load beam screens are compatible with expectations from laboratory studies of copper conditioning and deconditioning mechanisms, an extremely low carbon amount and the presence of CuO (non-native surface oxide) are observed on the high heat-load beam screens. The azimuthal distribution of CuO correlates with the density and energy of electron impingement. Such chemical modifications increase the SEY and inhibit the full conditioning of affected surfaces. This work shows a direct correlation between the abnormal LHC heat load and the surface properties of its beam screens, opening the door to the development of curative solutions to overcome this critical limitation.

Poster WEPAB339 [2.247 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB339

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

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WEPAB384

Design and Beam Dynamics of the Electron Lens for Space Charge Compensation in SIS18

electron, space-charge, simulation, solenoid

3614

S. Artikova, D. Ondreka, K. Schulte-Urlichs, P.J. Spiller
GSI, Darmstadt, Germany

An electron lens for space charge compensation is being developed at GSI to increase the ion beam intensities in SIS18 for the FAIR project. It uses an electron beam of 10A maximum current at 30keV. The maximum magnetic field on-axis is 0.6T, considerably higher than the field of the existing electron cooler. The magnetic system of the lens consists of solenoids and toroids. The toroids’ vertical field component creates a significant horizontal orbit deflection in the circulating low rigidity ion beam. To correct this deflection, four correction dipoles have been introduced. As common for electron lenses, the high-power electron beam is not dumped at ground potential, but rather in a collector with a small bias potential with respect to the cathode. The present design foresees a collector at -27kV, leading to a power dissipation of 30kW, distributed over a large surface area by placing the collector in an appropriately shaped magnetic field of a pre-collector solenoid. This contribution reports on the design of the lens and presents the results of beam transport simulations for the electron beam (with space charge) and a representative ion beam, performed using the 3D CST STUDIO.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB384

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paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 31 August 2021

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WEPAB400

Forced Coupling Resonance Driving Terms

coupling, optics, resonance, simulation

3646

A. Wegscheider, R. Tomás García
CERN, Meyrin, Switzerland

At the LHC, coupling is routinely measured using forced oscillations of the beam through excitation with an AC-dipole. The driving of the particle motion has an impact on the measurement of resonance driving terms. Recent findings suggest that the current models describing the forced motion are neglecting a local effect of the AC-dipole, creating a jump of the amplitude of the resonance driving terms. This work presents a study of the improvement of coupling measurements for typical LHC optics as well as its upgrade project HL-LHC, by using the new model.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB400

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

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WEPAB410

Finite Element Analyses of Synchrotron Radiation Induced Stress in Beryllium Synch-Light Mirrors

simulation, synchrotron, scattering, operation

3664

Y. Lushtak, Y. Li, A. Lyndaker
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Air Force Research Laboratory Directorate for Mathematical and Physical Sciences National Institute of General Medical Sciences Empire State Development - NYSTAR
Mirrors made of high purity beryllium are used in particle accelerators to extract synchrotron radiation (SR) in the visible range for transverse and longitudinal particle beam profile measurements. Be is a high-strength, high thermal conductivity material. As a low-Z metal, it allows high-energy photons to penetrate the mirror body, so that majority of the SR power is dissipated, resulting in a significantly reduced thermal stress and distortion on the mirror surface. In this paper, we describe a Finite Element Analysis method of accurately simulating the SR-induced thermal stress on the beryllium mirrors at the Cornell Electron Storage Ring at various particle beam conditions. The simulations consider the energy dependence of X-ray attenuation in beryllium. The depth-dependent distribution of the power absorbed by the mirror is represented by separate heating zones within the mirror model. The results help set the operational safety limit for the mirrors-ensuring that the SR-induced thermal stress is below the elastic deformation limit and estimate the mirror surface distortion at high beam currents. The simulated surface distortion is consistent with optical measurements.

Poster WEPAB410 [0.942 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB410

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

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THXA05

A Fast Method of 2D Calculation of Coherent Synchrotron Radiation Wakefield in Relativistic Beams

radiation, electron, synchrotron, synchrotron-radiation

3696

J. Tang, Z. Huang, G. Stupakov
SLAC, Menlo Park, California, USA

Coherent Synchrotron Radiation (CSR) is regarded as one of the most important reasons that limit beam brightness in modern accelerators. CSR wakefield is often computed in a 1D assuming a line charge, which can become invalid when the beam has a large transverse extension and small bunch length. On the other hand, the existing 2D or 3D codes are often computationally inefficient or incomplete. In our previous work * we developed a new model for fast computation of 2D CSR wakefield in relativistic beams with Gaussian distribution. Here we further generalize this model to achieve self-consistent computation compatible with arbitrary beam distribution and nonlinear magnetic lattice with particle tracking. These new features can enable us to perform realistic simulations and study the physics of CSR beyond 1D in electron beams with extreme short bunch length and high peak current.
* J. Tang and G. Stupakov. NAPAC2019, paper WEPLS09 (2019).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA05

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

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THXA07

Driven 3D Beam Oscillations for Optics Measurements in Synchrotrons

optics, synchrotron, betatron, emittance

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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THPAB001

Reaching the Sub Per Mil Level Coupling Corrections in the LHC

coupling, quadrupole, simulation, operation

3752

E.J. Høydalsvik, T.H.B. Persson
CERN, Geneva, Switzerland

The High Luminosity LHC (HL-LHC) is requiring sub per mil coupling correction, as defined by the closest tune approach. In this article, the current coupling correction strategy is analyzed in order to understand if it can robustly correct to these very low levels. The impact of realistic errors on the coupling correction is investigated with MAD-X simulations, including the influence of local coupling on the global coupling correction. Through simulations and measurements in the LHC, the effect of BPM noise on the coupling correction is analyzed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB001

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paper received ※ 11 May 2021 paper accepted ※ 28 July 2021 issue date ※ 23 August 2021

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THPAB026

Final Booster Complex Design for the Jefferson Lab Electron Ion Collider

collider, booster, electron, solenoid

3805

E.A. Nissen
JLab, Newport News, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. retains a license to publish or reproduce this manuscript for U.S. Government purposes.
In this work we show the final iteration of the design for the booster complex of the Jefferson Lab EIC, which would have brought the ions from an energy (proton) of 150 MeV up to 12.1 GeV. This complex would have consisted of two figure-8 rings. The Low Energy Booster (LEB) which would have accelerated its protons from 150 MeV to 8 GeV, and has had its lattice tweaked to increase the effectiveness of chromaticity cancellations. The High Energy Booster (HEB) would have brought the 8 GeV protons up to 12.1 GeV. The HEB would in the tunnel that was designed for the collider rings, sitting on top of them. It has had a bypass around the interaction region added, as well as a cooling solenoid installed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB026

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

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THPAB029

Dynamic Aperture Evaluation for the Hadron Storage Ring in the Electron-Ion Collider

dynamic-aperture, cavity, electron, proton

3812

Y. Luo, J.S. Berg, M. Blaskiewicz, W. Fischer, X. Gu, H. Lovelace III, C. Montag, R.B. Palmer, S. Peggs, V. Ptitsyn, F.J. Willeke, H. Witte
BNL, Upton, New York, USA
Y. Hao, D. Xu
FRIB, East Lansing, Michigan, USA
H. Huang
ODU, Norfolk, Virginia, USA
V.S. Morozov, E.A. Nissen, T. Satogata
JLab, Newport News, Virginia, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Electron-Ion Collider (EIC) is aiming at a design luminosity of 1e34 cm^-2s⁻¹. To maintain such a high luminosity, both beams in the EIC need an acceptable beam lifetime in the presence of the beam-beam interaction. For this purpose, we carried out weak-strong element-by-element particle tracking to evaluate the long-term dynamic aperture for the hadron ring lattice design. We improved our simulation code SimTrack to treat some new lattice design features, such as radially offset on-momentum orbits, coordinate transformations in the interaction region, etc. In this article, we will present the preliminary dynamic aperture calculation results with β^*- function scan, radial orbit shift, crossing angle collision, and magnetic field errors.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB029

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paper received ※ 17 May 2021 paper accepted ※ 01 September 2021 issue date ※ 28 August 2021

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THPAB083

Measurement of the Longitudinal Phase-Space of the APS Photo-Injector Beam

linac, cavity, gun, lattice

3963

Y. Sun
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.
An S-band photo-cathode RF gun (PCG) exists at the front of the linac. The high-brightness photoinjector beam is accelerated by the linac and and can be used for accelerator technology and beam physics R&D experiments in the Linac Extension Area (LEA). For some applications, the beam needs to be compressed by a magnetic bunch compressor in the middle of the linac. An S-band transverse-mode cavity (Tcav) is available at the end of the linac for beam longitudinal phase-space diagnostics. Beam commissioning experience of the Tcav is reported in this paper. The cavity rf conditioning and calibration was performed. There is a horizontally bending dipole magnet downstream of the Tcav, which kicks beam in the vertical plane. Beam image on a YAG screen downstream of the Tcav and dipole magnet contains the single-shot information of the longitudinal phase-space of the photo-injector beam. The first measurements of the longitudinal phase-space of the compressed and non-compressed photoinjector beam are discussed. Improvements of the measurement resolution are planned.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB083

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paper received ※ 25 May 2021 paper accepted ※ 12 July 2021 issue date ※ 21 August 2021

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THPAB168

Optics Measurement by Excitation of Betatron Oscillations in the CERN PSB

injection, optics, kicker, MMI

4078

E.H. Maclean, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, J. Dilly, E. Fol, H. Garcia Morales, M. Hofer, J. Keintzel, M. Le Garrec, T.E. Levens, L. Malina, T.H.B. Persson, T. Prebibaj, E. Renner, P.K. Skowroński, F. Soubelet, R. Tomás García, A. Wegscheider, L. van Riesen-Haupt
CERN, Geneva, Switzerland

Optics measurement from analysis of turn-by-turn BPM data of betatron oscillations excited with a kicker magnet has been employed very successfully in many machines but faces particular challenges in the CERN PSB where BPM to BPM phase advances are sub-optimal for optics reconstruction. Experience using turn-by-turn oscillation data for linear optics measurements during PSB commissioning in2021 is presented, with implications for the prospect of such techniques in the PSB more generally.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB168

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

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THPAB177

Simulation Model Improvements at the Cooler Synchrotron COSY Using the LOCO Algorithm

simulation, storage-ring, quadrupole, polarization

4111

V. Poncza, A. Lehrach
FZJ, Jülich, Germany
A. Lehrach, V. Poncza
RWTH, Aachen, Germany

Funding: ERC Advanced Grant (srEDM #694340) of the European Union
The JEDI (Jülich Electric Dipole moment Investigations) collaboration is searching for Electric Dipol Moments (EDMs) of charged particles in storage rings. In a stepwise approach, a first direct deuteron EDM measurement was performed at the Cooler Synchrotron COSY and design studies for a dedicated proton EDM storage ring are underway. In an experiment with a polarized beam in a storage ring, an EDM leads to a vertical polarization buildup. However, the vertical polarization component is also induced by systematic effects such as magnet misalignments. To investigate systematic effects individually and to support data analysis, a realistic simulation model of the storage ring is needed. In this paper, the development of such a model based on the Bmad software library is presented. Furthermore, various systematic effects and their impact on the spin motion in COSY are investigated and quantified by means of beam and spin tracking simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB177

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 12 August 2021

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THPAB220

Multibunch Studies for LCLS-II High Energy Upgrade

cavity, linac, emittance, 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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THPAB233

Could "Flakes" of Neutral Paramagnetic or Dipolar Molecules Explain Beam Losses in the LHC?

solenoid, electron, vacuum, electromagnetic-fields

4254

G. Franchetti
GSI, Darmstadt, Germany
F. Zimmermann
CERN, Meyrin, Switzerland

"Flakes" of neutral water or oxygen molecules carrying an electric or magnetic dipole moment can be attracted and trapped by the electromagnetic field of the circulating LHC proton beam. The possible presence of such flakes in the vacuum system could explain beam losses and beam instabilities encountered during the 2017 and 2018 LHC runs, and the observed effect of an external magnetic field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB233

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paper received ※ 09 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

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THPAB238

An Overview of the Collective Effects and Impedance Calculation for the EIC

electron, vacuum, simulation, wakefield

4266

A. Blednykh, D.M. Gassner, B. Podobedov, S. Verdú-Andrés
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
M. Blaskiewicz, C. Hetzel, B. Lepore, V.H. Ranjbar, M.P. Sangroula, P. Thieberger, G. Wang, Q. Wu
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.
A new high-luminosity Electron-Ion Collider (EIC) is being designed at Brookhaven National Laboratory (BNL). Stable operation of the electron beam at an average current of 2.5A within 1100 bunches with a 7mm bunch length is one of the challenging tasks in achieving an electron-proton luminosity of 1033-1034 cm^-2 ses⁻¹ range. Beam induced heating, short-range and long-range wakefield analysis is discussed for some of the vacuum components of the electron storage ring (ESR), the hadron storage ring (HSR), and the rapid cycling synchrotron (RCS) and as well as the impact of the collective effects on the beam stability.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB238

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paper received ※ 15 May 2021 paper accepted ※ 24 June 2021 issue date ※ 29 August 2021

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THPAB282

Optimization Design of Four-Point Vibration Isolation Support for Spallation Neutron Source Vibration Magnet

ISOL, experiment, damping, extraction

4352

J.S. Zhang, J.X. Chen, H.Y. He, L. Liu, R.H. Liu, C.J. Ning, G.Y. Wang, A.X. Wang, J.B. Yu, Y.J. Yu, D.H. Zhu
IHEP CSNS, Guangdong Province, People’s Republic of China
L. Kang
IHEP, Beijing, People’s Republic of China

Chinese spallation neutron source (CSNS) RCS of the dipole magnets by 25 Hz sinusoidal alternating current (AC) with dc bias field, because the magnet will produce eddy current effect caused by the vibration, this safe and reliable operation of the long-term impact of magnets, so need to CSNS/RCS dipole magnets, a support system for dynamic characteristic research and the performance of vibration isolation design. The mechanical model of ac dipole magnet and support system is first established, and ANSYS theoretical modal analysis and experimental modal verification are carried out. On this basis, vibration isolation parameters of the four-point support system are studied. The theoretical analysis and the experimental results of modal parameters are consistent, which shows that the ANSYS analysis model is correct and reliable. The dynamic system parameter design method established in this paper can be applied to various equipment of AC power accelerator. The final experimental verification shows that the total displacement amplitude of the isolator to the Y direction of the magnet on the magnetic support decreases by 62.3%.

Poster THPAB282 [0.426 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB282

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paper received ※ 16 May 2021 paper accepted ※ 02 September 2021 issue date ※ 27 August 2021

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FRXB04

Newly Development of Ceramics Chamber with Integrated Pulsed Magnet for Super-Narrow Bore in KEK-PF

injection, kicker, multipole, vacuum

4524

C. Mitsuda, K. Harada, Y. Kobayashi, S. Nagahashi, T. Nogami, T. Obina, R. Takai, H. Takaki, T. Uchiyama, A. Ueda
KEK, Ibaraki, Japan
K. Hamaji, K. Iwamoto, A. Sasagawa, A. Yokoyama
KYOCERA Corporation, Higashiomi-city, Shiga, Japan
Y. Lu
Sokendai, Ibaraki, Japan

Ceramics chamber with integrated pulsed magnet (CCiPM) is a new air-core type magnet that has a plan to be used as a multipole injection magnet, a dipole injection kicker, and a fast correction kicker in the next-generation light source. The magnet coils are implanted completely into the thickness of cylindrical ceramic and integrated with ceramic structurally. The first CCiPM was developed for an internal diameter of 60 mm as a magnet bore to establish the basic production techniques. The technique has been enhanced to realize narrower bore over 3 years, and finally, the achieved internal diameters were 40 and 30 mm in newly developed CCiPM. These super small bores have an expectation to conform to the size of the vacuum beam duct in the ring of a future light source. New CCiPMs are under the off-line test to confirm the vacuum durability, electrical characteristics, and magnetic performance, and the beam test for the CCiPM with 30 mm diameter has also proceeded in parallel. The points of production technique and the recent results of the off-line test will be presented in this conference.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB04

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

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