IPAC2021 - List of Keywords (dynamic-aperture)

Paper	Title	Other Keywords	Page
MOPAB028	Using Machine Learning to Improve Dynamic Aperture Estimates	simulation, collider, hadron, operation	134
	F.F. Van der Veken, M. Giovannozzi, E.H. Maclean CERN, Geneva, Switzerland C.E. Montanari Bologna University, Bologna, Italy G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The dynamic aperture (DA) is an important concept in the study of nonlinear beam dynamics. Several analytical models used to describe the evolution of DA as a function of time, and to extrapolate to realistic time scales that would not be reachable otherwise due to computational limitations, have been successfully developed. Even though these models have been quite successful in the past, the fitting procedure is rather sensitive to several details. Machine Learning (ML) techniques, which have been around for decades and have matured into powerful tools ever since, carry the potential to address some of these challenges. In this paper, two applications of ML approaches are presented and discussed in detail. Firstly, ML has been used to efficiently detect outliers in the DA computations. Secondly, ML techniques have been applied to improve the fitting procedures of the DA models, thus improving their predictive power.
	Poster MOPAB028 [1.764 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB028
About •	paper received ※ 18 May 2021 paper accepted ※ 25 May 2021 issue date ※ 12 August 2021
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MOPAB062	A Single Dipole Source for Broad-Band Soft Photon Beamlines in Diamond-II	lattice, dipole, emittance, 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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MOPAB106	Enhancing the MOGA Optimization Process at ALS-U with Machine Learning	lattice, emittance, sextupole, storage-ring	387
	Y. Lu, M.P. Ehrlichman, T. Hellert, S.C. Leemann, H. Nishimura, C. Sun, M. Venturini LBNL, Berkeley, California, USA
	Funding: This research is funded by the US Department of Energy(BES & ASCR Programs), and supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231. The bare lattice optimization for the linear and nonlinear ALS-U storage ring lattice, even without reverse bending, comprises 11 degrees of freedom (DoF) and is therefore a very complex and highly time-consuming process. This design process relies heavily on multi-objective genetic algorithms (MOGA), usually requiring many months of experienced scientists’ time. The main problem lies in having to evaluate numbers of candidate lattices due to the stochastic process of MOGA. Although almost all of these candidates are eventually rejected, they nevertheless require extensive particle tracking to arrive at a Pareto front. We therefore propose a novel Machine Learning (ML) pipeline that nonlinear tracking is replaced by two well-trained neural networks (NNs) to predict dynamic aperture (DA) and momentum aperture (MA) for any lattice candidate. Initial training of these models takes only several minutes on conventional CPUs while predictions are then rendered near instantaneously. We present this novel method and demonstrate the resulting orders of magnitude speedup of the ML-enhanced MOGA process on a 2-DoF problem as well as first results on a more complex 11-DoF problem.
	Poster MOPAB106 [0.918 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB106
About •	paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 18 August 2021
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MOPAB119	Comparisons Between AT and Elegant Tracking	lattice, closed-orbit, simulation, emittance	432
	G. Penn, T. Hellert, M. Venturini LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DEAC02-05CH11231. The simulation codes Elegant* and Accelerator Toolbox (AT)** are both in common use for the study of particle accelerators and light sources. They use different software platforms and have different capabilities, so there is a strong motivation to be able to switch from one version to another to achieve different goals. In addition, it is useful to directly compare results for benchmarking studies. We discuss differences in tracking methods and results for various elements, and explore the impact on simulations performed with lattices designed for the ALS-U. In addition to single-particle tracking, global properties such as chromaticity, dynamics aperture, momentum aperture and beam lifetime are also investigated. We have also developed scripts to translate AT lattices into elegant lattice files to facilitate comparisons. * M. Borland, Advanced Photon Source LS-287, September 2000. ** A. Terebilo, Particle Accelerators Conference 2001, p. 3203.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB119
About •	paper received ※ 20 May 2021 paper accepted ※ 31 May 2021 issue date ※ 30 August 2021
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MOPAB180	AGS Dynamic Aperture at Injection of Polarized Protons and Helions	coupling, proton, injection, extraction	610
	K. Hock, H. Huang, F. Méot, N. Tsoupas 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. Polarized helions are part of the physics program for the future EIC. An AC dipole has been installed in the AGS Booster to preserve polarization as helions are accelerated to \|Ggamma\|=10.5. Extraction from the AGS Booster at \|Ggamma\|=7.5 is possible but: would involve crossing an intrinsic resonance in the AGS, and would be the lowest rigidity beam injected into the AGS, and therefore experiences strong distortions of the optical functions because of the AGS two partial snakes. This lower rigidity would exacerbate the optical distortions from the snake, reducing the dynamic aperture. A comparison of the dynamic aperture of protons at Ggamma=4.5 to that of helions at \|Ggamma\|=7.5 and \|Ggamma\|=10.5 show that extraction at \|Ggamma\|=10.5 provides a larger dynamic aperture. This larger aperture would allow helions to be placed inside the spin tune gap generated by the two partial helices in AGS earlier in the cycle.
	Poster MOPAB180 [0.453 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB180
About •	paper received ※ 17 May 2021 paper accepted ※ 31 May 2021 issue date ※ 20 August 2021
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MOPAB224	Optimization and Error Studies for the USSR HMBA Lattice	lattice, injection, SRF, booster	730
	L. Hoummi, N. Carmignani, L.R. Carver, S.M. Liuzzo, T.P. Perron, S.M. White ESRF, Grenoble, France I.A. Ashanin, S.M. Polozov MEPhI, Moscow, Russia T. Kulevoy ITEP, Moscow, Russia T. Kulevoy NRC, Moscow, Russia
	Several new accelerator facilities will be built in Russia in the next few years. One of those facilities is a 6 GeV storage ring (SR) light source, the Ultimate Source of Synchrotron Radiation (USSR) to be built in Protvino, near Moscow. The Cremlin+ project aims to incorporate in this activity the best experience of European Accelerator Laboratories. The optimization of such optics including realistic errors and a commissioning-like sequence of corrections, using Multi-Objective Genetic Algorithms (NSGA-II) is presented. Several corrections schemes are also tested.
	Poster MOPAB224 [1.164 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB224
About •	paper received ※ 12 May 2021 paper accepted ※ 01 June 2021 issue date ※ 13 August 2021
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TUPAB216	Modeling Particle Stability Plots for Accelerator Optimization Using Adaptive Sampling	network, simulation, collider, resonance	1923
	M. Schenk, L. Coyle, T. Pieloni EPFL, Lausanne, Switzerland M. Giovannozzi, A. Mereghetti CERN, Meyrin, Switzerland E. Krymova, G. Obozinski SDSC, Lausanne, Switzerland
	Funding: This work is partially funded by the Swiss Data Science Center (SDSC), project C18-07. One key aspect of accelerator optimization is to maximize the dynamic aperture (DA) of a ring. Given the number of adjustable parameters and the compute-intensity of DA simulations, this task can benefit significantly from efficient search algorithms of the available parameter space. We propose to gradually train and improve a surrogate model of the DA from SixTrack simulations while exploring the parameter space with adaptive sampling methods. Here we report on a first model of the particle stability plots using convolutional generative adversarial networks (GAN) trained on a subset of SixTrack numerical simulations for different ring configurations of the Large Hadron Collider at CERN.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB216
About •	paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 22 August 2021
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TUPAB233	Diffusive Models for Nonlinear Beam Dynamics	hadron, collider, experiment, beam-losses	1976
	C.E. Montanari, A. Bazzani Bologna University, Bologna, Italy M. Giovannozzi, C.E. Montanari CERN, Geneva, Switzerland
	Diffusive models for representing the nonlinear beam dynamics in a circular accelerator ring have been developed in recent years. The novelty of the work presented here with respect to older approaches is that the functional form of the diffusion coefficient is derived from the time stability estimate of the Nekhoroshev theorem. In this paper, we discuss the latest results obtained for simple models of nonlinear betratron motion.
	Poster TUPAB233 [0.574 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB233
About •	paper received ※ 11 May 2021 paper accepted ※ 23 June 2021 issue date ※ 23 August 2021
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TUPAB235	Dynamic Aperture Optimization in the EIC Electron Storage Ring with Two Interaction Points	electron, lattice, sextupole, collider	1984
	D. Marx, Y. Li, C. Montag, S. Tepikian, F.J. Willeke BNL, Upton, New York, USA Y. Cai, Y.M. Nosochkov SLAC, Menlo Park, California, USA G.H. Hoffstaetter, J.E. Unger Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 and by SLAC under Contract No. DE-AC02-76SF00515 with the U.S. Department of Energy. In the Electron-Ion Collider (EIC), which is currently being designed for construction at Brookhaven National Laboratory, electrons from the electron storage ring will collide with hadrons, producing luminosities up to 10³⁴ cm^-2 s^-1. The baseline design includes only one interaction point (IP), and optics have been found with a suitable dynamic aperture in each dimension. However, the EIC project asks for the option of a second IP. The strong focusing required at the IPs creates a very large natural chromaticity (about -125 in the vertical plane for the ring). Compensating this linear chromaticity while simultaneously controlling the nonlinear chromaticity to high order to achieve a sufficient momentum acceptance of 1% (10 σ) at 18 GeV is a considerable challenge. A scheme to compensate higher-order chromatic effects from 2 IPs by setting the phase advance between them does not, by itself, provide the required momentum acceptance for the EIC Electron Storage Ring. A thorough design of the nonlinear optics is underway to increase the momentum acceptance using multiple sextupole families, and the latest results are presented here.
	Poster TUPAB235 [3.426 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB235
About •	paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 20 August 2021
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WEPAB006	EIC Crab Cavity Multipole Analysis	cavity, multipole, collider, simulation	2589
	Q. Wu, Y. Luo, B.P. Xiao BNL, Upton, New York, USA S.U. De Silva ODU, Norfolk, Virginia, USA J.A. Mitchell CERN, Geneva, Switzerland
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. Crab cavities are specialized RF devices designed for colliders targeting high luminosities. It is a straightforward solution to retrieve head-on collision with crossing angle existing to fast separate both beams after collision. The Electron Ion Collider (EIC) has a crossing angle of 25 mrad, and will use local crabbing to minimize the dynamic aperture requirement throughout the rings. The current crab cavity design for the EIC lacks axial symmetry. Therefore, their higher order components of the fundamental deflecting mode have a potential of affecting the long-term beam stability. We present here the multipole analysis and preliminary particle tracking results from the current crab cavity design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB006
About •	paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 16 August 2021
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WEPAB026	Optics Measurements and Correction Plans for the HL-LHC	coupling, optics, luminosity, dipole	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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WEPAB033	Lattice Design of the CEPC Collider Ring for a High Luminosity Scheme	luminosity, collider, lattice, quadrupole	2679
	Y. Wang, S. Bai, J. Gao, B. Wang, D. Wang, Y. Wei, J. Wu, C.H. Yu, J.Y. Zhai, Y. Zhang, Y.S. Zhu IHEP, Beijing, People’s Republic of China Y. Zhang University of Chinese Academy of Sciences, Beijing, People’s Republic of China
	A high luminosity scheme of the CEPC has been proposed aiming to increase the luminosity mainly at Higgs and Z modes. In this paper, the high luminosity scheme will be introduced briefly, including the beam parameters and RF staging. Then, the lattice design of the CEPC collider ring for the high luminosity scheme will be presented, including the bare lattice design and dynamic aperture optimization at Higgs energy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB033
About •	paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 27 August 2021
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WEPAB119	Beam Injection with a Pulsed Nonlinear Magnet Into the HALF Storage Ring	injection, storage-ring, lattice, multipole	2878
	G. Liu, W. Li, L. Wang, P.N. Wang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	The nonlinear optics of the HALF storage ring are well optimized to make it possible to inject the beam with the pulsed multipole injection scheme. In this paper, the injection scheme is studied with an innovatively designed pulsed nonlinear magnet. The layout and parameters of the injection system are well designed based on the acceptance analysis. The injection process is simulated with particle tracking is presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB119
About •	paper received ※ 20 May 2021 paper accepted ※ 29 July 2021 issue date ※ 13 August 2021
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THPAB002	Lattice Design for BEPCII Upgrade	cavity, lattice, quadrupole, electron	3756
	H. Geng, W.B. Liu, J. Qiu, J. Xing, C.H. Yu, Y. Zhang IHEP, Beijing, People’s Republic of China
	The Beijing Electron Positron Collider II (BEPCII) has achieved a series of achievements in high-energy physics study. Along with the deepening of the research, more important physics is expected in higher energy regions (>2.1 GeV). As the upper limit of BEPCII design energy is 2.1GeV, an urgent upgrade is required for BEPCII. To achieve a higher luminosity at higher energy, the number of RF cavities is expected to be doubled. In this paper, the lattice design for the upgrade of BEPCII is studied. The dynamic aperture tracking result shows that the lattice could meet the injection requirement of the BEPCII beam with a reasonable margin.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB002
About •	paper received ※ 14 May 2021 paper accepted ※ 17 June 2021 issue date ※ 14 August 2021
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THPAB016	Revisit of Nonlinear Dynamics in Hénon Map Using Square Matrix Method	resonance, lattice, sextupole, site	3788
	Y. Hao, K.J. Anderson FRIB, East Lansing, Michigan, USA L.H. Yu BNL, Upton, New York, USA
	Funding: Work supported by the Accelerator Stewardship program, award number DE-SC0019403 with the U.S. Department of Energy Hénon map (2D or 4D) represents a thin lens sextupole in an otherwise linear lattice and had been well studied for many decades. We revisit the nonlinear properties of the Hénon map with the aid of the square matrix method and Arnold theorem, including acquiring the resonance structure and amplitude-dependent frequency.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB016
About •	paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 17 August 2021
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THPAB029	Dynamic Aperture Evaluation for the Hadron Storage Ring in the Electron-Ion Collider	cavity, electron, proton, dipole	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB029
About •	paper received ※ 17 May 2021 paper accepted ※ 01 September 2021 issue date ※ 28 August 2021
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THPAB089	Lattice Design for a Future Plan of UVSOR Synchrotron	emittance, optics, lattice, quadrupole	3970
	E. Salehi, M. Katoh UVSOR, Okazaki, Japan M. Katoh HSRC, Higashi-Hiroshima, Japan
	UVSOR is a 750 MeV synchrotron light source with a moderately small emittance of about 17nm. We surveyed the periodic solutions by drawing a tie diagram and mapped the emittance and the dynamic aperture on the tune diagram. The aim of this work is to search for a possible low emittance solution without a major change of the lattice. Although, we could not find a solution which has a drastically small emittance, we have found a few solutions which has a significantly smaller emittance than present value. They may be useful for some special low emittance operation modes dedicated to developments on new light sources technologies and their applications.
	Poster THPAB089 [1.592 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB089
About •	paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 16 August 2021
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THPAB201	A Machine Learning Technique for Dynamic Aperture Computation	network, simulation, hadron, distributed	4172
	B. Dalena, M. Ben Ghali CEA-IRFU, Gif-sur-Yvette, France
	Currently, dynamic aperture calculations of high-energy hadron colliders are performed through computer simulations, which are both a resource-heavy and time-costly processes. The aim of this study is to use a reservoir computing machine learning model in order to achieve a faster extrapolation of dynamic aperture values. A recurrent echo-state network (ESN) architecture is used as a basis for this work. Recurrent networks are better fitted to extrapolation tasks while the reservoir echo-state structure is computationally effective. Model training and validation is conducted on a set of "seeds" corresponding to the simulation results of different machine configurations. Adjustments in the model architecture, manual metric and data selection, hyper-parameters tuning and the introduction of new parameters enabled the model to reliably achieve good performance on examining testing sets.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB201
About •	paper received ※ 14 May 2021 paper accepted ※ 22 July 2021 issue date ※ 02 September 2021
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THPAB206	Validating pyORBIT for Modeling Beam Dynamics in the IOTA Ring	space-charge, proton, octupole, emittance	4190
	R. Li UW-Madison/PD, Madison, Wisconsin, USA J.-F. Ostiguy, T. Sen Fermilab, Batavia, Illinois, USA
	Funding: Supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The Integrable Optics Test Accelerator (IOTA) ring is a new Fermilab facility dedicated to beam physics experiments, currently operating with 150 MeV electrons. Space charge effects are expected to be significant when it operates with 2.5 MeV protons. In this contribution, we present results of a suite of validation tests of PyORBIT, a PICstyle space charge code. Single particle dynamics of quasiintegrable optics using an octupole string in IOTA is compared with MADX, and shown to be in good agreement. Requirements for the convergence of space charge computations are systematically established and when possible, tests involving space charge are compared with theoretical predictions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB206
About •	paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 12 August 2021
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Paper

Title

Other Keywords

Page

MOPAB028

Using Machine Learning to Improve Dynamic Aperture Estimates

simulation, collider, hadron, operation

134

F.F. Van der Veken, M. Giovannozzi, E.H. Maclean
CERN, Geneva, Switzerland
C.E. Montanari
Bologna University, Bologna, Italy
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The dynamic aperture (DA) is an important concept in the study of nonlinear beam dynamics. Several analytical models used to describe the evolution of DA as a function of time, and to extrapolate to realistic time scales that would not be reachable otherwise due to computational limitations, have been successfully developed. Even though these models have been quite successful in the past, the fitting procedure is rather sensitive to several details. Machine Learning (ML) techniques, which have been around for decades and have matured into powerful tools ever since, carry the potential to address some of these challenges. In this paper, two applications of ML approaches are presented and discussed in detail. Firstly, ML has been used to efficiently detect outliers in the DA computations. Secondly, ML techniques have been applied to improve the fitting procedures of the DA models, thus improving their predictive power.

Poster MOPAB028 [1.764 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB028

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paper received ※ 18 May 2021 paper accepted ※ 25 May 2021 issue date ※ 12 August 2021

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MOPAB062

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

lattice, dipole, emittance, 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

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

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MOPAB106

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

lattice, emittance, sextupole, storage-ring

387

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

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

Poster MOPAB106 [0.918 MB]

DOI •

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

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

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MOPAB119

Comparisons Between AT and Elegant Tracking

lattice, closed-orbit, simulation, emittance

432

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

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

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

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

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MOPAB180

AGS Dynamic Aperture at Injection of Polarized Protons and Helions

coupling, proton, injection, extraction

610

K. Hock, H. Huang, F. Méot, N. Tsoupas
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.
Polarized helions are part of the physics program for the future EIC. An AC dipole has been installed in the AGS Booster to preserve polarization as helions are accelerated to |Ggamma|=10.5. Extraction from the AGS Booster at |Ggamma|=7.5 is possible but: would involve crossing an intrinsic resonance in the AGS, and would be the lowest rigidity beam injected into the AGS, and therefore experiences strong distortions of the optical functions because of the AGS two partial snakes. This lower rigidity would exacerbate the optical distortions from the snake, reducing the dynamic aperture. A comparison of the dynamic aperture of protons at Ggamma=4.5 to that of helions at |Ggamma|=7.5 and |Ggamma|=10.5 show that extraction at |Ggamma|=10.5 provides a larger dynamic aperture. This larger aperture would allow helions to be placed inside the spin tune gap generated by the two partial helices in AGS earlier in the cycle.

Poster MOPAB180 [0.453 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB180

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paper received ※ 17 May 2021 paper accepted ※ 31 May 2021 issue date ※ 20 August 2021

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MOPAB224

Optimization and Error Studies for the USSR HMBA Lattice

lattice, injection, SRF, booster

730

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

Several new accelerator facilities will be built in Russia in the next few years. One of those facilities is a 6 GeV storage ring (SR) light source, the Ultimate Source of Synchrotron Radiation (USSR) to be built in Protvino, near Moscow. The Cremlin+ project aims to incorporate in this activity the best experience of European Accelerator Laboratories. The optimization of such optics including realistic errors and a commissioning-like sequence of corrections, using Multi-Objective Genetic Algorithms (NSGA-II) is presented. Several corrections schemes are also tested.

Poster MOPAB224 [1.164 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB224

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paper received ※ 12 May 2021 paper accepted ※ 01 June 2021 issue date ※ 13 August 2021

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TUPAB216

Modeling Particle Stability Plots for Accelerator Optimization Using Adaptive Sampling

network, simulation, collider, resonance

1923

M. Schenk, L. Coyle, T. Pieloni
EPFL, Lausanne, Switzerland
M. Giovannozzi, A. Mereghetti
CERN, Meyrin, Switzerland
E. Krymova, G. Obozinski
SDSC, Lausanne, Switzerland

Funding: This work is partially funded by the Swiss Data Science Center (SDSC), project C18-07.
One key aspect of accelerator optimization is to maximize the dynamic aperture (DA) of a ring. Given the number of adjustable parameters and the compute-intensity of DA simulations, this task can benefit significantly from efficient search algorithms of the available parameter space. We propose to gradually train and improve a surrogate model of the DA from SixTrack simulations while exploring the parameter space with adaptive sampling methods. Here we report on a first model of the particle stability plots using convolutional generative adversarial networks (GAN) trained on a subset of SixTrack numerical simulations for different ring configurations of the Large Hadron Collider at CERN.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB216

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paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 22 August 2021

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TUPAB233

Diffusive Models for Nonlinear Beam Dynamics

hadron, collider, experiment, beam-losses

1976

C.E. Montanari, A. Bazzani
Bologna University, Bologna, Italy
M. Giovannozzi, C.E. Montanari
CERN, Geneva, Switzerland

Diffusive models for representing the nonlinear beam dynamics in a circular accelerator ring have been developed in recent years. The novelty of the work presented here with respect to older approaches is that the functional form of the diffusion coefficient is derived from the time stability estimate of the Nekhoroshev theorem. In this paper, we discuss the latest results obtained for simple models of nonlinear betratron motion.

Poster TUPAB233 [0.574 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB233

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paper received ※ 11 May 2021 paper accepted ※ 23 June 2021 issue date ※ 23 August 2021

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TUPAB235

Dynamic Aperture Optimization in the EIC Electron Storage Ring with Two Interaction Points

electron, lattice, sextupole, collider

1984

D. Marx, Y. Li, C. Montag, S. Tepikian, F.J. Willeke
BNL, Upton, New York, USA
Y. Cai, Y.M. Nosochkov
SLAC, Menlo Park, California, USA
G.H. Hoffstaetter, J.E. Unger
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 and by SLAC under Contract No. DE-AC02-76SF00515 with the U.S. Department of Energy.
In the Electron-Ion Collider (EIC), which is currently being designed for construction at Brookhaven National Laboratory, electrons from the electron storage ring will collide with hadrons, producing luminosities up to 10³⁴ cm^-2 s^-1. The baseline design includes only one interaction point (IP), and optics have been found with a suitable dynamic aperture in each dimension. However, the EIC project asks for the option of a second IP. The strong focusing required at the IPs creates a very large natural chromaticity (about -125 in the vertical plane for the ring). Compensating this linear chromaticity while simultaneously controlling the nonlinear chromaticity to high order to achieve a sufficient momentum acceptance of 1% (10 σ) at 18 GeV is a considerable challenge. A scheme to compensate higher-order chromatic effects from 2 IPs by setting the phase advance between them does not, by itself, provide the required momentum acceptance for the EIC Electron Storage Ring. A thorough design of the nonlinear optics is underway to increase the momentum acceptance using multiple sextupole families, and the latest results are presented here.

Poster TUPAB235 [3.426 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB235

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

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WEPAB006

EIC Crab Cavity Multipole Analysis

cavity, multipole, collider, simulation

2589

Q. Wu, Y. Luo, B.P. Xiao
BNL, Upton, New York, USA
S.U. De Silva
ODU, Norfolk, Virginia, USA
J.A. Mitchell
CERN, Geneva, Switzerland

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Crab cavities are specialized RF devices designed for colliders targeting high luminosities. It is a straightforward solution to retrieve head-on collision with crossing angle existing to fast separate both beams after collision. The Electron Ion Collider (EIC) has a crossing angle of 25 mrad, and will use local crabbing to minimize the dynamic aperture requirement throughout the rings. The current crab cavity design for the EIC lacks axial symmetry. Therefore, their higher order components of the fundamental deflecting mode have a potential of affecting the long-term beam stability. We present here the multipole analysis and preliminary particle tracking results from the current crab cavity design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB006

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paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 16 August 2021

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WEPAB026

Optics Measurements and Correction Plans for the HL-LHC

coupling, optics, luminosity, dipole

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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WEPAB033

Lattice Design of the CEPC Collider Ring for a High Luminosity Scheme

luminosity, collider, lattice, quadrupole

2679

Y. Wang, S. Bai, J. Gao, B. Wang, D. Wang, Y. Wei, J. Wu, C.H. Yu, J.Y. Zhai, Y. Zhang, Y.S. Zhu
IHEP, Beijing, People’s Republic of China
Y. Zhang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

A high luminosity scheme of the CEPC has been proposed aiming to increase the luminosity mainly at Higgs and Z modes. In this paper, the high luminosity scheme will be introduced briefly, including the beam parameters and RF staging. Then, the lattice design of the CEPC collider ring for the high luminosity scheme will be presented, including the bare lattice design and dynamic aperture optimization at Higgs energy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB033

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paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 27 August 2021

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WEPAB119

Beam Injection with a Pulsed Nonlinear Magnet Into the HALF Storage Ring

injection, storage-ring, lattice, multipole

2878

G. Liu, W. Li, L. Wang, P.N. Wang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

The nonlinear optics of the HALF storage ring are well optimized to make it possible to inject the beam with the pulsed multipole injection scheme. In this paper, the injection scheme is studied with an innovatively designed pulsed nonlinear magnet. The layout and parameters of the injection system are well designed based on the acceptance analysis. The injection process is simulated with particle tracking is presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB119

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paper received ※ 20 May 2021 paper accepted ※ 29 July 2021 issue date ※ 13 August 2021

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THPAB002

Lattice Design for BEPCII Upgrade

cavity, lattice, quadrupole, electron

3756

H. Geng, W.B. Liu, J. Qiu, J. Xing, C.H. Yu, Y. Zhang
IHEP, Beijing, People’s Republic of China

The Beijing Electron Positron Collider II (BEPCII) has achieved a series of achievements in high-energy physics study. Along with the deepening of the research, more important physics is expected in higher energy regions (>2.1 GeV). As the upper limit of BEPCII design energy is 2.1GeV, an urgent upgrade is required for BEPCII. To achieve a higher luminosity at higher energy, the number of RF cavities is expected to be doubled. In this paper, the lattice design for the upgrade of BEPCII is studied. The dynamic aperture tracking result shows that the lattice could meet the injection requirement of the BEPCII beam with a reasonable margin.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB002

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paper received ※ 14 May 2021 paper accepted ※ 17 June 2021 issue date ※ 14 August 2021

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THPAB016

Revisit of Nonlinear Dynamics in Hénon Map Using Square Matrix Method

resonance, lattice, sextupole, site

3788

Y. Hao, K.J. Anderson
FRIB, East Lansing, Michigan, USA
L.H. Yu
BNL, Upton, New York, USA

Funding: Work supported by the Accelerator Stewardship program, award number DE-SC0019403 with the U.S. Department of Energy
Hénon map (2D or 4D) represents a thin lens sextupole in an otherwise linear lattice and had been well studied for many decades. We revisit the nonlinear properties of the Hénon map with the aid of the square matrix method and Arnold theorem, including acquiring the resonance structure and amplitude-dependent frequency.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB016

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

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THPAB029

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

cavity, electron, proton, dipole

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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THPAB089

Lattice Design for a Future Plan of UVSOR Synchrotron

emittance, optics, lattice, quadrupole

3970

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

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

Poster THPAB089 [1.592 MB]

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

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

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THPAB201

A Machine Learning Technique for Dynamic Aperture Computation

network, simulation, hadron, distributed

4172

B. Dalena, M. Ben Ghali
CEA-IRFU, Gif-sur-Yvette, France

Currently, dynamic aperture calculations of high-energy hadron colliders are performed through computer simulations, which are both a resource-heavy and time-costly processes. The aim of this study is to use a reservoir computing machine learning model in order to achieve a faster extrapolation of dynamic aperture values. A recurrent echo-state network (ESN) architecture is used as a basis for this work. Recurrent networks are better fitted to extrapolation tasks while the reservoir echo-state structure is computationally effective. Model training and validation is conducted on a set of "seeds" corresponding to the simulation results of different machine configurations. Adjustments in the model architecture, manual metric and data selection, hyper-parameters tuning and the introduction of new parameters enabled the model to reliably achieve good performance on examining testing sets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB201

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paper received ※ 14 May 2021 paper accepted ※ 22 July 2021 issue date ※ 02 September 2021

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THPAB206

Validating pyORBIT for Modeling Beam Dynamics in the IOTA Ring

space-charge, proton, octupole, emittance

4190

R. Li
UW-Madison/PD, Madison, Wisconsin, USA
J.-F. Ostiguy, T. Sen
Fermilab, Batavia, Illinois, USA

Funding: Supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The Integrable Optics Test Accelerator (IOTA) ring is a new Fermilab facility dedicated to beam physics experiments, currently operating with 150 MeV electrons. Space charge effects are expected to be significant when it operates with 2.5 MeV protons. In this contribution, we present results of a suite of validation tests of PyORBIT, a PICstyle space charge code. Single particle dynamics of quasiintegrable optics using an octupole string in IOTA is compared with MADX, and shown to be in good agreement. Requirements for the convergence of space charge computations are systematically established and when possible, tests involving space charge are compared with theoretical predictions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB206

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paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 12 August 2021

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