NAPAC2019 - List of Keywords (lattice)

Paper	Title	Other Keywords	Page
MOZBA5	Optimized Linear and Second Order Chromaticity Setpoints for the Advanced Photon Source Upgrade	sextupole, simulation, MMI, photon	70
	Y.P. 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. The nominal single particle dynamics optimizations of the Advanced Photon Source upgrade (APS-U) lattice are performed with dense numerical simulations of local momentum acceptance and dynamic acceptance. These simulations are quite time consuming, which may take weeks for optimizing one setpoint of linear chromaticity. In this paper, an alternative optimization method is adopted to generate optimized linear and second order chromaticity setpoints for the Advanced Photon Source upgrade lattice. This method is efficient in computing time needed, which is capable to generate a grid of optimized chromaticity setpoints in a relatively short time. The performance of these lattice solutions are verified by simulations with reasonable errors. These lattice solutions with different linear (or second order) chromaticity may be useful for the future APS-U commissioning and operations.
	Slides MOZBA5 [3.350 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBA5
About •	paper received ※ 31 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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MOPLM03	Correlations Between Beta Beating and APS-U Single Particle Dynamics Performance	focusing, sextupole, quadrupole, simulation	95
	Y.P. 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. In the optimizations and evaluations process of the Advanced Photon Source upgrade (APS-U) lattice, it was observed that there are negative correlations between beta beating and APS-U single particle dynamics performance (such as dynamic acceptance and local momentum acceptance). These correlations are not always present due to different reasons. In this paper, a systematic simulation study is performed to understand the correlations between beta beating and APS-U single particle dynamics performance. Relatively high beta beatings are generated to reveal these effects.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM03
About •	paper received ※ 31 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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MOPLM08	Controlling Transient Collective Instabilities During Swap-Out Injection	injection, octupole, emittance, simulation	110
	R.R. Lindberg ANL, Lemont, Illinois, USA
	Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 Previous work has shown that collective instabilities at injection may reduce injection efficiency even for on-axis injection as planned for the APS-Upgrade. Stability at injection is governed by a number of factors, including phase-space mismatch between injected and stored bunch, strength of the impedance, degree of nonlinearities, and feedback. We find that the large tune-shift with amplitude of the most recent APS-U lattice largely tames the transient instability via Landau damping, and show that using octupoles to increase the nonlinear tune shift can stabilize the transient instability at injection that plagued a previously unstable lattice. R.R. Lindberg, M. Borland, and A. Blednykh, Proc. of NA-PAC 2016, pp. 901
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLM08
About •	paper received ※ 24 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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MOPLH11	Nanostructured Photocathodes for Spin-Polarized Electron Beams	cathode, polarization, scattering, electron	196
	E.J. Montgomery, C. Jing, S. Poddar Euclid Beamlabs LLC, Bolingbrook, USA A. Afanasev GWU, Washington, USA R. Kumar, G.J. Salamo University of Arkansas, Fayetteville, Arkansas, USA S. Zhang JLab, Newport News, Virginia, USA
	Funding: Work supported by US DOE Office of Science, Office of Nuclear Physics, SBIR grant DESC0019559. CNM work supported by US DOE Office of Science, Basic Energy Sciences, contract DE-AC02-06CH11357. We present progress on incorporation of nanopillar arrays into spin-polarized gallium arsenide photocathodes in pursuit of record high tolerance to ion back-bombardment. Our goal is to exceed the 400 Coulomb record for a high polarization milliampere-class electron source set at Jefferson Laboratory in 2017, while maintaining high quantum efficiency (QE) and spin polarization with a superlattice. Because the Mie effect is resonant, uniformity and careful control over nanostructure geometry is key. We report excellent uniformity and straight sidewall geometry with improved optical absorption using a painstakingly optimized inductively coupled plasma reactive ion etch. We also report the application of Kerker theory to spin-polarized photocathode nanopillar arrays, setting new requirements on nanostructure dimensions to avoid spoiling spin polarization. Finally, we also report initial steps toward re-establishing U.S. production of strained superlattice photocathodes towards integration with nanopillar arrays.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH11
About •	paper received ※ 03 September 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019
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MOPLO14	From Start to Finish: Using 3D Printing Techniques to Build CBETA	permanent-magnet, dipole, experiment, collider	263
	G.J. Mahler, S.J. Brooks, S.M. Trabocchi BNL, Upton, New York, USA
	Funding: NYSERDA contract with BNL The extensive use of a simple 3D printer allowed for fast prototyping and development of many components used to build CBETA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO14
About •	paper received ※ 14 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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TUYBB4	Online Modelling and Optimization of Nonlinear Integrable Systems	optics, experiment, octupole, network	318
	N. Kuklev, Y.K. Kim University of Chicago, Chicago, Illinois, USA A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by National Science Foundation award PHY-1549132, the Center for Bright Beams. Fermi Research Alliance operates Fermilab under Contract DE-AC02-07CH11359 with the US Dept. of Energy. Nonlinear integrable optics was recently proposed as a design approach to increase the limits on beam brightness and intensity imposed by fast collective instabilities. To study these systems experimentally, a new research electron and proton storage ring, the Integrable Optics Test Accelerator, was constructed and recently commissioned at Fermilab. Beam-based diagnostics and online modelling of nonlinear systems presents unique challenges - in this paper, we report on our efforts to develop optimization methods suited for such lattices. We explore the effectiveness of neural networks as fast online surrogate estimators, and integrate them into a beam-based tuning algorithm. We also develop a method of knob dimensionality reduction and subsequent robust multivariate optimization for maximizing key performance metrics under complicated lattice optics constraints.
	Slides TUYBB4 [5.771 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBB4
About •	paper received ※ 03 September 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019
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TUZBA5	Algorithms Used in Action and Phase Jump Analysis to Estimate Corrections to Quadrupole Errors in the Interaction Regions of the LHC	quadrupole, software, interaction-region, experiment	349
	J.F. Cardona UNAL, Bogota D.C, Colombia
	Action and phase jump analysis has been used to estimate corrector strengths in the high luminosity interaction regions of the LHC. It has been proven that these corrections are effective to eliminate the beta-beating that is generated in those important regions and that propagates around the ring. More recently, it was also shown that the beta-beating at the interaction point can also be suppressed by combining k-modulation measurements with action and phase jump analysis. Applying this technique to the re-commissioning of the LHC in 2021 requires a good knowledge of the software developed for action and phase jump analysis over the years. In this paper a detailed description is made of all the modules that are part of this software and the corresponding algorithms.
	Slides TUZBA5 [0.431 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBA5
About •	paper received ※ 22 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUZBB2	Reaching Low Emittance in Synchrotron Light Sources by Using Complex Bends	emittance, quadrupole, dipole, focusing	352
	G.M. Wang, J. Choi, O.V. Chubar, Y. Hidaka, T.V. Shaftan, S.K. Sharma, V.V. Smaluk, C.J. Spataro, T. Tanabe BNL, Upton, New York, USA N.A. Mezentsev BINP SB RAS, Novosibirsk, Russia
	All modern projects of low-emittance synchrotrons follow Multi-Bend Achromat approach. The low emittance is realized by arranging small horizontal beta-function and dispersion in the bending magnets, the number of which varies from 4 to 9 magnets per cell. We propose an alternative way to reach low emittance by use of a lattice element that we call "Complex Bend", instead of regular dipole magnets. The Complex Bend is a new concept of bending magnet consisting of a number of dipole poles interleaved with strong alternate focusing so as to maintain the beta-function and dispersion oscillating at very low values. The details of Complex Bend, considerations regarding the choice of optimal parameters, thoughts for its practical realization and use in low-emittance lattices, are discussed. MBA: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.495.2446&rep=rep1&type=pdf ** Complex Bend: Phys. Rev. Accel. Beams 21, 100703 (2018)
	Slides TUZBB2 [7.894 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBB2
About •	paper received ※ 01 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUZBB6	Nonlinear Tune-Shift Measurements in the Integrable Optics Test Accelerator	experiment, optics, electron, betatron	368
	S. Szustkowski, S. Chattopadhyay Northern Illinois University, DeKalb, Illinois, USA S. Chattopadhyay, A.L. Romanov, A. Valishev Fermilab, Batavia, Illinois, USA N. Kuklev University of Chicago, Chicago, Illinois, USA
	Funding: US Department of Energy, Office of High Energy Physics, General Accelerator Research and Development (GARD) Program The first experimental run of Fermilab’s Integrable Optics Test Accelerator (IOTA) ring aimed at testing the concept of nonlinear integrable beam optics. In this report we present the preliminary results of the studies of a nonlinear focusing system with two invariants of motion realized with the special elliptic-potential magnet. The key measurement of this experiment was the horizontal and vertical betatron tune shift as a function of transverse amplitude. A vertical kicker strength was varied to change the betatron amplitude for several values of the nonlinear magnet strength. The turn-by-turn positions of the 100 MeV electron beam at twenty-one beam position monitors around the ring were captured and used for the analysis of phase-space trajectories.
	Slides TUZBB6 [12.888 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBB6
About •	paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLM03	Adjoint Approach to Accelerator Lattice Design	focusing, simulation, quadrupole, plasma	376
	T.M. Antonsen, B.L. Beaudoin, L. Dovlatyan, I. Haber UMD, College Park, Maryland, USA
	Funding: Supported by USDoE DESC0010301 Accelerator lattices are designed using computer codes that solve the equations of motion for charged particles in both prescribed and self-consistent fields. These codes are run in a mode in which particles enter a lattice region, travel for a finite distance, and have their coordinates recorded to assess various figures of merit (FoMs). The lattice is then optimized by varying the positions and strengths of the focusing elements. This optimization is done in a high dimensional parameter space, requiring multiple simulations of the particle trajectories to determine the dependence of the confinement on the many parameters. Sophisticated algorithms for this optimization are being introduced. However, the process is still time consuming. We propose to alter the design process using "adjoint" techniques []. Incorporation of an "adjoint" calculation of the trajectories and self-fields can, in several runs, determine the gradient in parameter space of a given FoM with respect to all lattice parameters. It includes naturally self-fields and can be embedded in existing codes such as WARP or Vorpal. The theoretical basis for the method and several applications will be presented. T. Antonsen, D. Chernin, J. Petillo, Adjoint Approach to Beam Optics Sensitivity Based on Hamiltonian Particle Dynamics, 2018 arXiv:1807.07898, Physics of Plasmas 26, 013109 (2019).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM03
About •	paper received ※ 23 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019
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TUPLM07	First Experimental Observations of the Plasma-Cascade Instability in the CeC PoP Accelerator	electron, plasma, experiment, solenoid	379
	I. Petrushina SUNY SB, Stony Brook, New York, USA Y.C. Jing, V. Litvinenko, J. Ma, I. Pinayev, G. Wang, Y.H. Wu BNL, Upton, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA K. Shih SBU, Stony Brook, New York, USA
	Preservation of the beam quality is important for attaining the desirable properties of the beam. Collective effects can produce an instability severely degrading beam emittance, momentum spread and creating filamentation of the beam. Microbunching instability for beams traveling along a curved trajectory, and space charge driven parametric transverse instabilities are well-known and in-depth studied. However, none of the above include a microbunching longitudinal instability driven by modulations of the transverse beam size. This phenomenon was observed for the first time during the commissioning of the CeC PoP experiment. Based on the dynamics of this instability we named it a Plasma-Cascade Instability (PCI). PCI can strongly intensify longitudinal micro-bunching originating from the beam’s shot noise, and even saturate it. Resulting random density and energy microstructures in the beam can become a serious problem for generating high quality electron beams. On the other hand, such instability can drive novel high-power sources of broadband radiation. In this paper we present our experimental observations of the PCI and the supporting results of the numerical simulations.
	Poster TUPLM07 [17.319 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM07
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLM08	Experimental Studies of Single Invariant Quasi-Integrable Nonlinear Optics at IOTA	octupole, experiment, optics, alignment	383
	N. Kuklev, Y.K. Kim University of Chicago, Chicago, Illinois, USA S. Nagaitsev, A.L. Romanov, A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by National Science Foundation award PHY-1549132, the Center for Bright Beams. Fermi Research Alliance operates Fermilab under Contract DE-AC02-07CH11359 with the US Dept. of Energy. The Integrable Optics Test Accelerator is a research electron and proton storage ring recently commissioned at the Fermilab Accelerator Science and Technology facility. Its research program is focused on testing novel techniques for improving beam stability and quality, notably the concept of non-linear integrable optics. In this paper, we report on run 1 results of experimental studies of a quasi-integrable transverse focusing system with one invariant of motion, a Henon-Heiles type system implemented with octupole magnets. Good agreement with simulations is demonstrated on key parameters of achievable tune spread, dynamic aperture, and invariant conservation. We also outline current simulation and hardware improvement efforts for run 2, planned for fall of 2019.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM08
About •	paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLM21	Optical Stochastic Cooling Program at Fermilab’s Integrable Optics Test Accelerator	experiment, radiation, electron, optics	418
	J.D. Jarvis, S. Chattopadhyay, V.A. Lebedev, H. Piekarz, P. Piot, A.L. Romanov, J. Ruan Fermilab, Batavia, Illinois, USA S. Chattopadhyay, P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: Fermi National Accelerator Laboratory is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. Beam cooling enables an increase of peak and average luminosities and significantly expands the discovery potential of colliders. Optical Stochastic Cooling (OSC) is a high-bandwidth cooling technique that will advance the present state-of-the-art, stochastic-cooling rate by more than three orders of magnitude. A proof-of-principle demonstration with protons or heavy ions involves prohibitive costs, risks and technological challenges; however, exploration of OSC with electrons is a cost-effective alternative for studying the beam-cooling physics, optical systems and diagnostics. The ability to demonstrate OSC was a key requirement in the design of Fermilab’s Integrable Optics Test Accelerator (IOTA) ring. The IOTA program will explore the physics and technology of OSC in amplified and non-amplified configurations. We also plan to investigate the cooling and manipulation of a single electron stored in the ring. The OSC apparatus is currently being fabricated, and installation will begin in the fall of 2019. In this contribution, we will describe the IOTA OSC program, the upcoming passive-OSC experimental runs and ongoing preparations for an amplified-OSC experiment
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM21
About •	paper received ※ 27 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019
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TUPLO01	Dual-Function Electron Ring-Ion Booster Design for JLEIC High-Energy Option	booster, electron, collider, quadrupole	529
	J.L. Martinez Marin, B. Mustapha ANL, Lemont, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. As part of the alternative design approach for the Jeffer-son Laboratory Electron-Ion Collider (JLEIC) ion com-plex, the electron storage ring (e-ring) is consolidated to also serve as a large booster for the ions. The goal of reaching 16 GeV/u or higher for all ions using only room-temperature magnets forces the re-design of the e-ring because of magnetic field and lattice limitations. The new design is challenging due to several imposed constraints: (1) use of room-temperature magnets, (2) avoiding transi-tion crossing, and (3) maintaining the size and shape of the original e-ring design as much as possible. A design study is presented for a 16 GeV/u large ion booster after analyzing different alternatives that use: (1) combined-function magnets, (2) large quadrupoles or (3) quadrupole doublets in the lattice design. This design boosts the injection energy to the collider ring from 8 GeV (proton-equivalent) in the original baseline design to 16 GeV/u for all ions which is beneficial for the high-energy option of JLEIC of 200 GeV or higher. A scheme for adapting the new large ion booster design to also serve as electron storage ring is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO01
About •	paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLO12	Off-Momentum Optics Correction in RHIC	optics, closed-orbit, experiment, injection	556
	G. Robert-Demolaize, A. Marusic, V. Ptitsyn 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. Future operations of the electron-ion collider eRHIC call for beams circulating off of the magnetic center of all arc elements. In order to ensure that both stable beam conditions and the desired circumference change can be achieved, dedicated experiments were conducted during RHIC Run18, which included the first off-momentum linear optics correction. This article reviews the experimental setup as well as the dedicated algorithm for optics correction, and presents the measured radial excursion and residual off-momentum beta-beat.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO12
About •	paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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WEXBA3	CSR Phase Space Dilution in CBETA	simulation, linac, radiation, shielding	605
	W. Lou, G.H. Hoffstaetter, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA C.E. Mayes SLAC, Menlo Park, California, USA
	CBETA, the Cornell BNL ERL Test Accelerator, will be the first multi-turn Energy Recovery Linac (ERL) with SRF accelerating cavities and Fixed Field Alternating gradient (FFA) beamline. While CBETA gives promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. To investigate the CSR effects on CBETA, we used the established simulation code Bmad to track a bunch with different parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Potential ways to mitigate the effect involving varying phase advances are being investigated.
	Slides WEXBA3 [6.121 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEXBA3
About •	paper received ※ 28 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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WEPLS03	Analytical Expression for a N-Turn Trajectory in the Presence of Quadrupole Magnetic Errors	quadrupole, betatron, experiment, simulation	772
	Y. Rodriguez Garcia, J.F. Cardona UNAL, Bogota D.C, Colombia Y. Rodriguez Garcia UAN, Bogotá D.C., Colombia
	The action and phase jump method is a technique, based on the use of turn-by-turn experimental data in a circular accelerator, to find and measure local sources of magnetic errors through abrupt changes in the values of action and phase. At this moment, this method uses at least one pair of adjacent BPMs (Beam Position Monitors) to estimate the action and phase at one particular position in the accelerator. In this work, we propose a theoretical expression to describe the trajectory of a charged particle for an arbitrary number of turns when a magnetic error is present in the accelerator. This expression might help to estimate action and phase at one particular position of the accelerator using only one BPM in contrast to the current method that needs at least two BPMs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS03
About •	paper received ※ 26 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLS04	Simulations of Low Energy Au⁷⁸⁺ Losses in RHIC	electron, MMI, optics, closed-orbit	775
	G. Robert-Demolaize, K.A. Drees, Y. Luo BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The RHIC Run19 BES-II program features the commissioning of the Low Energy RHIC electron Cooling (LEReC) Project, which uses electron cooling techniques to compensate for intra-beam scattering and thus to improve the luminosity lifetime. During RHIC operations at 3.85 GeV (beam energy) with LEReC, one needs to ensure that the electron beam energy is properly matched for cooling purposes: if so, some of the circulating Au-79 ions can recombine with an electron, turning into Au-78 and circulating with a large momentum offset. Part of the LEReC commissioning steps is therefore to drive a maximized number of Au-78 ions towards a chosen location of the RHIC mechanical aperture to generate particle showers that can be detected by a Recombination Monitor outside the cryostat. This article introduces the baseline lattice design, then discusses the few scenarios considered for optimizing Au-78 losses at a given location. Each scenario is then simulated using new tracking tools for generating beam loss maps.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS04
About •	paper received ※ 27 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLS05	Simulation Analysis of the LCLS-II Injector using ACE3P and IMPACT	cavity, simulation, emittance, booster	779
	D.A. Bizzozero, J. Qiang LBNL, Berkeley, California, USA L. Ge, Z. Li, C.-K. Ng, L. Xiao SLAC, Menlo Park, California, USA
	Funding: This work is supported by the Director of the Office of Science of the US Department of Energy under contracts DEAC02-05CH11231 and DE-AC02-76-SF00515. The LCLS-II beam injector system consists of a 186 MHz normal-conducting RF gun, a two-cell 1.3 GHz normal-conducting buncher cavity, two transverse focusing solenoids, and eight 1.3 GHz 9-cell Tesla-like super-conducting booster cavities. With a coordinated effort between LBNL and SLAC, we have developed a simulation workflow combining the electromagnetic field solvers from ACE3P with the beam dynamics modeling code IMPACT. This workflow will be used to improve performance and minimize beam emittance for given accelerator structures through iterative optimization. In our current study, we use this workflow to compare beam quality parameters between using 2D axisymmetric field profiles and fully 3D non-axisymmetric fields caused by geometrical asymmetries (e.g. RF coupler ports).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS05
About •	paper received ※ 20 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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WEPLS11	Simulation of Transparent Spin Experiment in RHIC	polarization, closed-orbit, resonance, experiment	789
	H. Huang, Y.S. Derbenev, F. Lin, V.S. Morozov, Y. Zhang JLab, Newport News, Virgina, USA P. Adams, H. Huang, F. Méot, V. Ptitsyn, W.B. Schmidke BNL, Upton, New York, USA Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Funding: Work supported by the U.S. DOE under Contracts No. DE-AC05-06OR23177 and DE-AC02-98CH10886. The transparent spin mode has been proposed as a new technique for preservation and control of the spin polari-zation of ion beams in a synchrotron. The ion rings of the proposed Jefferson Lab Electron-Ion Collider (JLEIC) adopted this technique in their figure-8 design. The transparent spin mode can also be setup in a racetrack with two identical Siberian snakes. There is a proposal to test the predicted features of the spin transparent mode in Relativistic Heavy Ion Collider (RHIC), which already has all of the necessary hardware capabilities. We have earlier analytically estimated the setup parameters and developed a preliminary experimental plan. In this paper we describe simulation setup and benchmarking for the proposed experiment using a Zgoubi model of RHIC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS11
About •	paper received ※ 03 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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WEPLE08	Parallel Tracking-Based Modeling of Gas Scattering and Loss Distributions in Electron Storage Rings	scattering, simulation, storage-ring, electron	901
	M. Borland 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. Estimation of gas scattering lifetimes in storage rings is typically done using a simple approach that can readily be performed by hand. A more sophisticated approach uses linear mapping of the angular dynamic acceptance around the ring and allows including variation of gas pressure and composition. However, neither approach is appropriate for highly nonlinear lattices, in which the angular acceptance does not map according to the linear optics. Further, these approaches provide no detailed information about the location of losses. To address these limitations, a tracking-based approach was implemented in the program Pelegant. We describe the implementation and performance of this method, as well as several applications to the Advanced Photon Source Upgrade. M. Borland, J. Carter, H. Cease, and B. Stillwell, Proc. IPAC 2015, 546. ** Y. Wang and M. Borland, AIP Conf. Proc. 877, 241 (2006).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE08
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THZBA4	Characterization and Modeling of High-Intensity Evolution in the SNS Beam Test Facility	emittance, simulation, diagnostics, controls	954
	K.J. Ruisard, A.V. Aleksandrov, S.M. Cousineau ORNL, Oak Ridge, Tennessee, USA Z.L. Zhang ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. Partial support by NSF Accelerator Science grant 1535312 Modern high-power accelerators are charged with delivering reliable beam with low losses. Resolving the complex dynamics arising from space charge and nonlinear forces requires detailed models of the accelerator and particle-in-cell simulation. There has historically been discrepancy between simulated and measured beam distributions, particularly at the low-density halo level. The Beam Test Facility (BTF) at the Spallation Neutron Source is outfitted to study beam evolution in a high-power linear accelerator MEBT. This includes capability for high-dimensional measurements of the post-RFQ beam distribution, including interplane correlations that may be the key to accurate simulation. Beam is transported through a 4.6 m FODO channel (9.5 cells) to a second distribution measurement stage. Plans for validating simulations against BTF measurements of beam evolution in the FODO channel are discussed.
	Slides THZBA4 [8.316 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THZBA4
About •	paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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Paper

Title

Other Keywords

Page

MOZBA5

Optimized Linear and Second Order Chromaticity Setpoints for the Advanced Photon Source Upgrade

sextupole, simulation, MMI, photon

70

Y.P. 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.
The nominal single particle dynamics optimizations of the Advanced Photon Source upgrade (APS-U) lattice are performed with dense numerical simulations of local momentum acceptance and dynamic acceptance. These simulations are quite time consuming, which may take weeks for optimizing one setpoint of linear chromaticity. In this paper, an alternative optimization method is adopted to generate optimized linear and second order chromaticity setpoints for the Advanced Photon Source upgrade lattice. This method is efficient in computing time needed, which is capable to generate a grid of optimized chromaticity setpoints in a relatively short time. The performance of these lattice solutions are verified by simulations with reasonable errors. These lattice solutions with different linear (or second order) chromaticity may be useful for the future APS-U commissioning and operations.

Slides MOZBA5 [3.350 MB]

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MOPLM03

Correlations Between Beta Beating and APS-U Single Particle Dynamics Performance

focusing, sextupole, quadrupole, simulation

95

Y.P. 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.
In the optimizations and evaluations process of the Advanced Photon Source upgrade (APS-U) lattice, it was observed that there are negative correlations between beta beating and APS-U single particle dynamics performance (such as dynamic acceptance and local momentum acceptance). These correlations are not always present due to different reasons. In this paper, a systematic simulation study is performed to understand the correlations between beta beating and APS-U single particle dynamics performance. Relatively high beta beatings are generated to reveal these effects.

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MOPLM08

Controlling Transient Collective Instabilities During Swap-Out Injection

injection, octupole, emittance, simulation

110

R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
Previous work has shown that collective instabilities at injection may reduce injection efficiency even for on-axis injection as planned for the APS-Upgrade*. Stability at injection is governed by a number of factors, including phase-space mismatch between injected and stored bunch, strength of the impedance, degree of nonlinearities, and feedback. We find that the large tune-shift with amplitude of the most recent APS-U lattice largely tames the transient instability via Landau damping, and show that using octupoles to increase the nonlinear tune shift can stabilize the transient instability at injection that plagued a previously unstable lattice.
* R.R. Lindberg, M. Borland, and A. Blednykh, Proc. of NA-PAC 2016, pp. 901

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MOPLH11

Nanostructured Photocathodes for Spin-Polarized Electron Beams

cathode, polarization, scattering, electron

196

E.J. Montgomery, C. Jing, S. Poddar
Euclid Beamlabs LLC, Bolingbrook, USA
A. Afanasev
GWU, Washington, USA
R. Kumar, G.J. Salamo
University of Arkansas, Fayetteville, Arkansas, USA
S. Zhang
JLab, Newport News, Virginia, USA

Funding: Work supported by US DOE Office of Science, Office of Nuclear Physics, SBIR grant DESC0019559. CNM work supported by US DOE Office of Science, Basic Energy Sciences, contract DE-AC02-06CH11357.
We present progress on incorporation of nanopillar arrays into spin-polarized gallium arsenide photocathodes in pursuit of record high tolerance to ion back-bombardment. Our goal is to exceed the 400 Coulomb record for a high polarization milliampere-class electron source set at Jefferson Laboratory in 2017, while maintaining high quantum efficiency (QE) and spin polarization with a superlattice. Because the Mie effect is resonant, uniformity and careful control over nanostructure geometry is key. We report excellent uniformity and straight sidewall geometry with improved optical absorption using a painstakingly optimized inductively coupled plasma reactive ion etch. We also report the application of Kerker theory to spin-polarized photocathode nanopillar arrays, setting new requirements on nanostructure dimensions to avoid spoiling spin polarization. Finally, we also report initial steps toward re-establishing U.S. production of strained superlattice photocathodes towards integration with nanopillar arrays.

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MOPLO14

From Start to Finish: Using 3D Printing Techniques to Build CBETA

permanent-magnet, dipole, experiment, collider

263

G.J. Mahler, S.J. Brooks, S.M. Trabocchi
BNL, Upton, New York, USA

Funding: NYSERDA contract with BNL
The extensive use of a simple 3D printer allowed for fast prototyping and development of many components used to build CBETA.

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TUYBB4

Online Modelling and Optimization of Nonlinear Integrable Systems

optics, experiment, octupole, network

318

N. Kuklev, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by National Science Foundation award PHY-1549132, the Center for Bright Beams. Fermi Research Alliance operates Fermilab under Contract DE-AC02-07CH11359 with the US Dept. of Energy.
Nonlinear integrable optics was recently proposed as a design approach to increase the limits on beam brightness and intensity imposed by fast collective instabilities. To study these systems experimentally, a new research electron and proton storage ring, the Integrable Optics Test Accelerator, was constructed and recently commissioned at Fermilab. Beam-based diagnostics and online modelling of nonlinear systems presents unique challenges - in this paper, we report on our efforts to develop optimization methods suited for such lattices. We explore the effectiveness of neural networks as fast online surrogate estimators, and integrate them into a beam-based tuning algorithm. We also develop a method of knob dimensionality reduction and subsequent robust multivariate optimization for maximizing key performance metrics under complicated lattice optics constraints.

Slides TUYBB4 [5.771 MB]

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TUZBA5

Algorithms Used in Action and Phase Jump Analysis to Estimate Corrections to Quadrupole Errors in the Interaction Regions of the LHC

quadrupole, software, interaction-region, experiment

349

J.F. Cardona
UNAL, Bogota D.C, Colombia

Action and phase jump analysis has been used to estimate corrector strengths in the high luminosity interaction regions of the LHC. It has been proven that these corrections are effective to eliminate the beta-beating that is generated in those important regions and that propagates around the ring. More recently, it was also shown that the beta-beating at the interaction point can also be suppressed by combining k-modulation measurements with action and phase jump analysis. Applying this technique to the re-commissioning of the LHC in 2021 requires a good knowledge of the software developed for action and phase jump analysis over the years. In this paper a detailed description is made of all the modules that are part of this software and the corresponding algorithms.

Slides TUZBA5 [0.431 MB]

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TUZBB2

Reaching Low Emittance in Synchrotron Light Sources by Using Complex Bends

emittance, quadrupole, dipole, focusing

352

G.M. Wang, J. Choi, O.V. Chubar, Y. Hidaka, T.V. Shaftan, S.K. Sharma, V.V. Smaluk, C.J. Spataro, T. Tanabe
BNL, Upton, New York, USA
N.A. Mezentsev
BINP SB RAS, Novosibirsk, Russia

All modern projects of low-emittance synchrotrons follow Multi-Bend Achromat approach*. The low emittance is realized by arranging small horizontal beta-function and dispersion in the bending magnets, the number of which varies from 4 to 9 magnets per cell. We propose an alternative way to reach low emittance by use of a lattice element that we call "Complex Bend"**, instead of regular dipole magnets. The Complex Bend is a new concept of bending magnet consisting of a number of dipole poles interleaved with strong alternate focusing so as to maintain the beta-function and dispersion oscillating at very low values. The details of Complex Bend, considerations regarding the choice of optimal parameters, thoughts for its practical realization and use in low-emittance lattices, are discussed.
* MBA: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.495.2446&rep=rep1&type=pdf
** Complex Bend: Phys. Rev. Accel. Beams 21, 100703 (2018)

Slides TUZBB2 [7.894 MB]

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TUZBB6

Nonlinear Tune-Shift Measurements in the Integrable Optics Test Accelerator

experiment, optics, electron, betatron

368

S. Szustkowski, S. Chattopadhyay
Northern Illinois University, DeKalb, Illinois, USA
S. Chattopadhyay, A.L. Romanov, A. Valishev
Fermilab, Batavia, Illinois, USA
N. Kuklev
University of Chicago, Chicago, Illinois, USA

Funding: US Department of Energy, Office of High Energy Physics, General Accelerator Research and Development (GARD) Program
The first experimental run of Fermilab’s Integrable Optics Test Accelerator (IOTA) ring aimed at testing the concept of nonlinear integrable beam optics. In this report we present the preliminary results of the studies of a nonlinear focusing system with two invariants of motion realized with the special elliptic-potential magnet. The key measurement of this experiment was the horizontal and vertical betatron tune shift as a function of transverse amplitude. A vertical kicker strength was varied to change the betatron amplitude for several values of the nonlinear magnet strength. The turn-by-turn positions of the 100 MeV electron beam at twenty-one beam position monitors around the ring were captured and used for the analysis of phase-space trajectories.

Slides TUZBB6 [12.888 MB]

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TUPLM03

Adjoint Approach to Accelerator Lattice Design

focusing, simulation, quadrupole, plasma

376

T.M. Antonsen, B.L. Beaudoin, L. Dovlatyan, I. Haber
UMD, College Park, Maryland, USA

Funding: Supported by USDoE DESC0010301
Accelerator lattices are designed using computer codes that solve the equations of motion for charged particles in both prescribed and self-consistent fields. These codes are run in a mode in which particles enter a lattice region, travel for a finite distance, and have their coordinates recorded to assess various figures of merit (FoMs). The lattice is then optimized by varying the positions and strengths of the focusing elements. This optimization is done in a high dimensional parameter space, requiring multiple simulations of the particle trajectories to determine the dependence of the confinement on the many parameters. Sophisticated algorithms for this optimization are being introduced. However, the process is still time consuming. We propose to alter the design process using "adjoint" techniques [*]. Incorporation of an "adjoint" calculation of the trajectories and self-fields can, in several runs, determine the gradient in parameter space of a given FoM with respect to all lattice parameters. It includes naturally self-fields and can be embedded in existing codes such as WARP or Vorpal. The theoretical basis for the method and several applications will be presented.
* T. Antonsen, D. Chernin, J. Petillo, Adjoint Approach to Beam Optics Sensitivity Based on Hamiltonian Particle Dynamics, 2018 arXiv:1807.07898, Physics of Plasmas 26, 013109 (2019).

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TUPLM07

First Experimental Observations of the Plasma-Cascade Instability in the CeC PoP Accelerator

electron, plasma, experiment, solenoid

379

I. Petrushina
SUNY SB, Stony Brook, New York, USA
Y.C. Jing, V. Litvinenko, J. Ma, I. Pinayev, G. Wang, Y.H. Wu
BNL, Upton, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
K. Shih
SBU, Stony Brook, New York, USA

Preservation of the beam quality is important for attaining the desirable properties of the beam. Collective effects can produce an instability severely degrading beam emittance, momentum spread and creating filamentation of the beam. Microbunching instability for beams traveling along a curved trajectory, and space charge driven parametric transverse instabilities are well-known and in-depth studied. However, none of the above include a microbunching longitudinal instability driven by modulations of the transverse beam size. This phenomenon was observed for the first time during the commissioning of the CeC PoP experiment. Based on the dynamics of this instability we named it a Plasma-Cascade Instability (PCI). PCI can strongly intensify longitudinal micro-bunching originating from the beam’s shot noise, and even saturate it. Resulting random density and energy microstructures in the beam can become a serious problem for generating high quality electron beams. On the other hand, such instability can drive novel high-power sources of broadband radiation. In this paper we present our experimental observations of the PCI and the supporting results of the numerical simulations.

Poster TUPLM07 [17.319 MB]

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TUPLM08

Experimental Studies of Single Invariant Quasi-Integrable Nonlinear Optics at IOTA

octupole, experiment, optics, alignment

383

N. Kuklev, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
S. Nagaitsev, A.L. Romanov, A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by National Science Foundation award PHY-1549132, the Center for Bright Beams. Fermi Research Alliance operates Fermilab under Contract DE-AC02-07CH11359 with the US Dept. of Energy.
The Integrable Optics Test Accelerator is a research electron and proton storage ring recently commissioned at the Fermilab Accelerator Science and Technology facility. Its research program is focused on testing novel techniques for improving beam stability and quality, notably the concept of non-linear integrable optics. In this paper, we report on run 1 results of experimental studies of a quasi-integrable transverse focusing system with one invariant of motion, a Henon-Heiles type system implemented with octupole magnets. Good agreement with simulations is demonstrated on key parameters of achievable tune spread, dynamic aperture, and invariant conservation. We also outline current simulation and hardware improvement efforts for run 2, planned for fall of 2019.

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TUPLM21

Optical Stochastic Cooling Program at Fermilab’s Integrable Optics Test Accelerator

experiment, radiation, electron, optics

418

J.D. Jarvis, S. Chattopadhyay, V.A. Lebedev, H. Piekarz, P. Piot, A.L. Romanov, J. Ruan
Fermilab, Batavia, Illinois, USA
S. Chattopadhyay, P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: Fermi National Accelerator Laboratory is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Beam cooling enables an increase of peak and average luminosities and significantly expands the discovery potential of colliders. Optical Stochastic Cooling (OSC) is a high-bandwidth cooling technique that will advance the present state-of-the-art, stochastic-cooling rate by more than three orders of magnitude. A proof-of-principle demonstration with protons or heavy ions involves prohibitive costs, risks and technological challenges; however, exploration of OSC with electrons is a cost-effective alternative for studying the beam-cooling physics, optical systems and diagnostics. The ability to demonstrate OSC was a key requirement in the design of Fermilab’s Integrable Optics Test Accelerator (IOTA) ring. The IOTA program will explore the physics and technology of OSC in amplified and non-amplified configurations. We also plan to investigate the cooling and manipulation of a single electron stored in the ring. The OSC apparatus is currently being fabricated, and installation will begin in the fall of 2019. In this contribution, we will describe the IOTA OSC program, the upcoming passive-OSC experimental runs and ongoing preparations for an amplified-OSC experiment

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TUPLO01

Dual-Function Electron Ring-Ion Booster Design for JLEIC High-Energy Option

booster, electron, collider, quadrupole

529

J.L. Martinez Marin, B. Mustapha
ANL, Lemont, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
As part of the alternative design approach for the Jeffer-son Laboratory Electron-Ion Collider (JLEIC) ion com-plex, the electron storage ring (e-ring) is consolidated to also serve as a large booster for the ions. The goal of reaching 16 GeV/u or higher for all ions using only room-temperature magnets forces the re-design of the e-ring because of magnetic field and lattice limitations. The new design is challenging due to several imposed constraints: (1) use of room-temperature magnets, (2) avoiding transi-tion crossing, and (3) maintaining the size and shape of the original e-ring design as much as possible. A design study is presented for a 16 GeV/u large ion booster after analyzing different alternatives that use: (1) combined-function magnets, (2) large quadrupoles or (3) quadrupole doublets in the lattice design. This design boosts the injection energy to the collider ring from 8 GeV (proton-equivalent) in the original baseline design to 16 GeV/u for all ions which is beneficial for the high-energy option of JLEIC of 200 GeV or higher. A scheme for adapting the new large ion booster design to also serve as electron storage ring is presented.

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TUPLO12

Off-Momentum Optics Correction in RHIC

optics, closed-orbit, experiment, injection

556

G. Robert-Demolaize, A. Marusic, V. Ptitsyn
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.
Future operations of the electron-ion collider eRHIC call for beams circulating off of the magnetic center of all arc elements. In order to ensure that both stable beam conditions and the desired circumference change can be achieved, dedicated experiments were conducted during RHIC Run18, which included the first off-momentum linear optics correction. This article reviews the experimental setup as well as the dedicated algorithm for optics correction, and presents the measured radial excursion and residual off-momentum beta-beat.

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WEXBA3

CSR Phase Space Dilution in CBETA

simulation, linac, radiation, shielding

605

W. Lou, G.H. Hoffstaetter, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
C.E. Mayes
SLAC, Menlo Park, California, USA

CBETA, the Cornell BNL ERL Test Accelerator, will be the first multi-turn Energy Recovery Linac (ERL) with SRF accelerating cavities and Fixed Field Alternating gradient (FFA) beamline. While CBETA gives promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. To investigate the CSR effects on CBETA, we used the established simulation code Bmad to track a bunch with different parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Potential ways to mitigate the effect involving varying phase advances are being investigated.

Slides WEXBA3 [6.121 MB]

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WEPLS03

Analytical Expression for a N-Turn Trajectory in the Presence of Quadrupole Magnetic Errors

quadrupole, betatron, experiment, simulation

772

Y. Rodriguez Garcia, J.F. Cardona
UNAL, Bogota D.C, Colombia
Y. Rodriguez Garcia
UAN, Bogotá D.C., Colombia

The action and phase jump method is a technique, based on the use of turn-by-turn experimental data in a circular accelerator, to find and measure local sources of magnetic errors through abrupt changes in the values of action and phase. At this moment, this method uses at least one pair of adjacent BPMs (Beam Position Monitors) to estimate the action and phase at one particular position in the accelerator. In this work, we propose a theoretical expression to describe the trajectory of a charged particle for an arbitrary number of turns when a magnetic error is present in the accelerator. This expression might help to estimate action and phase at one particular position of the accelerator using only one BPM in contrast to the current method that needs at least two BPMs.

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WEPLS04

Simulations of Low Energy Au⁷⁸⁺ Losses in RHIC

electron, MMI, optics, closed-orbit

775

G. Robert-Demolaize, K.A. Drees, Y. Luo
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The RHIC Run19 BES-II program features the commissioning of the Low Energy RHIC electron Cooling (LEReC) Project, which uses electron cooling techniques to compensate for intra-beam scattering and thus to improve the luminosity lifetime. During RHIC operations at 3.85 GeV (beam energy) with LEReC, one needs to ensure that the electron beam energy is properly matched for cooling purposes: if so, some of the circulating Au-79 ions can recombine with an electron, turning into Au-78 and circulating with a large momentum offset. Part of the LEReC commissioning steps is therefore to drive a maximized number of Au-78 ions towards a chosen location of the RHIC mechanical aperture to generate particle showers that can be detected by a Recombination Monitor outside the cryostat. This article introduces the baseline lattice design, then discusses the few scenarios considered for optimizing Au-78 losses at a given location. Each scenario is then simulated using new tracking tools for generating beam loss maps.

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WEPLS05

Simulation Analysis of the LCLS-II Injector using ACE3P and IMPACT

cavity, simulation, emittance, booster

779

D.A. Bizzozero, J. Qiang
LBNL, Berkeley, California, USA
L. Ge, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA

Funding: This work is supported by the Director of the Office of Science of the US Department of Energy under contracts DEAC02-05CH11231 and DE-AC02-76-SF00515.
The LCLS-II beam injector system consists of a 186 MHz normal-conducting RF gun, a two-cell 1.3 GHz normal-conducting buncher cavity, two transverse focusing solenoids, and eight 1.3 GHz 9-cell Tesla-like super-conducting booster cavities. With a coordinated effort between LBNL and SLAC, we have developed a simulation workflow combining the electromagnetic field solvers from ACE3P with the beam dynamics modeling code IMPACT. This workflow will be used to improve performance and minimize beam emittance for given accelerator structures through iterative optimization. In our current study, we use this workflow to compare beam quality parameters between using 2D axisymmetric field profiles and fully 3D non-axisymmetric fields caused by geometrical asymmetries (e.g. RF coupler ports).

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS05

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paper received ※ 20 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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WEPLS11

Simulation of Transparent Spin Experiment in RHIC

polarization, closed-orbit, resonance, experiment

789

H. Huang, Y.S. Derbenev, F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virgina, USA
P. Adams, H. Huang, F. Méot, V. Ptitsyn, W.B. Schmidke
BNL, Upton, New York, USA
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: Work supported by the U.S. DOE under Contracts No. DE-AC05-06OR23177 and DE-AC02-98CH10886.
The transparent spin mode has been proposed as a new technique for preservation and control of the spin polari-zation of ion beams in a synchrotron. The ion rings of the proposed Jefferson Lab Electron-Ion Collider (JLEIC) adopted this technique in their figure-8 design. The transparent spin mode can also be setup in a racetrack with two identical Siberian snakes. There is a proposal to test the predicted features of the spin transparent mode in Relativistic Heavy Ion Collider (RHIC), which already has all of the necessary hardware capabilities. We have earlier analytically estimated the setup parameters and developed a preliminary experimental plan. In this paper we describe simulation setup and benchmarking for the proposed experiment using a Zgoubi model of RHIC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS11

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paper received ※ 03 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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WEPLE08

Parallel Tracking-Based Modeling of Gas Scattering and Loss Distributions in Electron Storage Rings

scattering, simulation, storage-ring, electron

901

M. Borland
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.
Estimation of gas scattering lifetimes in storage rings is typically done using a simple approach that can readily be performed by hand. A more sophisticated approach uses linear mapping of the angular dynamic acceptance around the ring and allows including variation of gas pressure and composition*. However, neither approach is appropriate for highly nonlinear lattices, in which the angular acceptance does not map according to the linear optics. Further, these approaches provide no detailed information about the location of losses. To address these limitations, a tracking-based approach was implemented in the program Pelegant**. We describe the implementation and performance of this method, as well as several applications to the Advanced Photon Source Upgrade.
* M. Borland, J. Carter, H. Cease, and B. Stillwell, Proc. IPAC 2015, 546.
** Y. Wang and M. Borland, AIP Conf. Proc. 877, 241 (2006).

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE08

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paper received ※ 27 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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THZBA4

Characterization and Modeling of High-Intensity Evolution in the SNS Beam Test Facility

emittance, simulation, diagnostics, controls

954

K.J. Ruisard, A.V. Aleksandrov, S.M. Cousineau
ORNL, Oak Ridge, Tennessee, USA
Z.L. Zhang
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. Partial support by NSF Accelerator Science grant 1535312
Modern high-power accelerators are charged with delivering reliable beam with low losses. Resolving the complex dynamics arising from space charge and nonlinear forces requires detailed models of the accelerator and particle-in-cell simulation. There has historically been discrepancy between simulated and measured beam distributions, particularly at the low-density halo level. The Beam Test Facility (BTF) at the Spallation Neutron Source is outfitted to study beam evolution in a high-power linear accelerator MEBT. This includes capability for high-dimensional measurements of the post-RFQ beam distribution, including interplane correlations that may be the key to accurate simulation. Beam is transported through a 4.6 m FODO channel (9.5 cells) to a second distribution measurement stage. Plans for validating simulations against BTF measurements of beam evolution in the FODO channel are discussed.

Slides THZBA4 [8.316 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THZBA4

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paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019

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