NAPAC2019 - Table of Session: WEPLH (Wednesday Poster Session-Lake Huron)

Paper	Title	Page
WEPLH01	Longitudinal Beam Profile Measurement by Silicon Detector in Facility for Rare Isotope Beams at Michigan State University	799
	T. Maruta, P.N. Ostroumov, Q. Zhao FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University The Facility for Rare Isotope Beams (FRIB) includes a continuous wave superconducting linear accelerator designed to deliver 400 kW ion beams with energies above 200 MeV/u. The beam commissioning of the first three cryomodules took place in the summer of 2018. A temporary diagnostic station installed after the first three cryomodules included a Silicon Detector (SiD) to measure absolute energy and bunch shape of 40Ar and 86Kr beams accelerated up to 2.3 MeV/u. The beam longitudinal emittance was evaluated by measuring bunch shapes while the bunching field amplitude of the upstream resonator was varied. In this paper, we will present the SiD setup and measurement results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH01
About •	paper received ※ 28 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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WEPLH02	Experience with Long-Pulse Operation of the PIP2IT Warm Front End	803
	A.V. Shemyakin, J.-P. Carneiro, A.Z. Chen, D. Frolov, B.M. Hanna, R. Neswold, L.R. Prost, G.W. Saewert, A. Saini, V.E. Scarpine, A. Warner, J.Y. Wu Fermilab, Batavia, Illinois, USA C.J. Richard NSCL, East Lansing, Michigan, USA
	Funding: This manuscript has been authored 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 warm front end of the PIP2IT accelerator, assembled and commissioned at Fermilab, consists of a 15 mA DC, 30 keV H⁻ ion source, a 2-m long Low Energy Beam Transport (LEBT) line, a 2.1-MeV, 162.5 MHz CW RFQ, followed by a 10-m long Medium Energy Beam Transport (MEBT) line. A part of the commissioning efforts involves operation in regimes where the average beam power in this front end emulates the operation of the proposed PIP-II accelerator, which will have a duty factor of 1.1% or above. The maximum achieved power is 5 kW (2.1 MeV x 5 mA x 25 ms x 20 Hz). This paper describes the difficulties encountered and some of the solutions that were implemented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH02
About •	paper received ※ 20 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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WEPLH03	Redesign of ReA3 4-Rod RFQ	807
	A.S. Plastun, P.N. Ostroumov, A.C.C. Villari, Q. Zhao FRIB, East Lansing, Michigan, USA A.C.C. Villari, Q. Zhao NSCL, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. DoE Office of Science under Cooperative Agreement DE-SC0000661 and the NSF under Cooperative Agreement PHY-1102511, the State of Michigan and Michigan State University. The present RFQ of ReA3 reaccelerator at Michigan State University (MSU) has been commissioned in 2010. This 4-rod RFQ was designed to accelerate the prebunched 80.5 MHz beams with the lowest Q/A = 1/5. However, the lack of proper cooling limited the RFQ performance to the pulsed operation with the lowest Q/A = 1/4. The design voltage for Q/A = 1/5 has never been reached even in a pulsed mode due to the sparking. In 2016 we initiated the upgrade of ReA3 RFQ to support high duty cycle (up to CW) operation with Q/A = 1/5 beams. The upgrade included the new rods with trapezoidal modulation, and new stems with improved cooling. The redesigned 80.5 MHz RFQ will consume only 65% rf power of the present RFQ for Q/A = 1/5 beam. It will provide the transmission up to 78% for 16.1 MHz beams and 89% for 80.5 MHz beams. High reliability and efficiency of the RFQ are very important for the going-on reaccelerator upgrade to ReA6 and for future operation as a part of FRIB. The electrodes have been manufactured and are being installed. The RF and beam tests are scheduled to summer 2019.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH03
About •	paper received ※ 27 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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WEPLH04	Beam Envelope Reconstruction for FRIB-FS1 Transport Line Using Beam Position Monitors	810
	T. Yoshimoto, S. Cogan, J.L. Crisp, K. Fukushima, S.M. Lidia, T. Maruta, P.N. Ostroumov, A.S. Plastun, T. Zhang, Q. Zhao FRIB, East Lansing, Michigan, USA
	Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University. The Facility for Rare Isotope Beam (FRIB) includes a heavy ion superconducting (SC) linac. Recently we completed beam commissioning of the Linac Segment 1 (LS1) and 45° bend section of the Folding Segment 1 (FS1). Four ion species, 40Ar⁹⁺, 20Ne⁶⁺, 86Kr¹⁷⁺ and 129Xe²⁶⁺ were successfully accelerated to a beam energy of 20.3 MeV/u. We explored the possibility of non-invasive beam diagnostics for online beam envelope monitoring based on beam quadrupole moments derived from Beam Position Monitors (BPMs). In future operations, various ion beam species will be accelerated and minimization of beam tuning time is critical. To address this requirement, it is beneficial to use BPMs to obtain beam Twiss parameters instead of wire scanners. This paper reports the results of BPM-based beam Twiss parameters evolution in the FS1. R. E. Shafer, "Laser Diagnostic for High Current H beams", Proc. 1998 Beam Instrumentation Workshop (Stanford). A.I.P. Conf. Proceedings, (451), 191.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH04
About •	paper received ※ 27 August 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019
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WEPLH05	Characterization and Performance of Plasma Window for Gas Flow Restriction in Different Geometries
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	A. Lajoie NSCL, East Lansing, Michigan, USA J. Gao, F. Marti FRIB, East Lansing, Michigan, USA
	Funding: This work is supported by NSF Award PHY-1565546. The plasma window is a DC cascaded arc whose function is to restrict gas flow from a high pressure region to a low pressure region without the use of any solid separation. As a result, the plasma window allows a greater pressure to be maintained than otherwise possible. This is a beneficial characteristic for gas charge strippers for ion accelerators, since the higher pressures enable the stripper to be shorter and allow the same amount of stripping interactions. The flow rate reduction is established by the increase in gas temperature from the power deposited into the plasma via the cathodes, resulting in a dramatically increased viscosity. The flow rate reduction, depends on the properties of the plasma, including the electron density and temperature, pressure, and electrical conductivity. Understanding these properties in multiple arc geometries - in this work having either 6 mm or 10 mm channel diameter - provides a means optimizing the plasma window for a given design. Determinations of the properties for different conditions are shown, and results are compared with a PLASIMO simulation, which has been shown to yield comparable properties to measurements in an argon arc*. A. Hershcovitch, Phys. Plasma 5, 2130 (1998). J. A. Nolen and F. Marti, Rev. Accel. Sci. Tech. 6, 221 (2013). *G. M. W. Kroesen et al., Plas. Chem. and Plas. Proc. 10, 531 (1990).
	Slides MOYBB5 [4.132 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOYBB5
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WEPLH06	Commissioning Status of the FRIB Front End	813
	H.T. Ren, J. Brandon, N.K. Bultman, K.D. Davidson, E. Daykin, T. Elkin, B. Galecka, P.E. Gibson, L. Hodges, K. Holland, D.D. Jager, M.G. Konrad, B.R. Kortum, S.M. Lidia, G. Machicoane, I.M. Malloch, H. Maniar, T. Maruta, G. Morgan, D.G. Morris, P. Morrison, A.C. Morton, P.N. Ostroumov, A.S. Plastun, E. Pozdeyev, X. Rao, T. Russo, J.W. Stetson, R. Walker, J. Wei, Y. Yamazaki, T. Yoshimoto, Q. Zhao, S. Zhao FRIB, East Lansing, Michigan, USA S. Renteria NSCL, East Lansing, Michigan, USA
	Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The FRIB Front End was successfully commissioned in 2017 with commissioning goals achieved and Key Per-formance Parameters (KPP) demonstrated for both 40Ar⁹⁺ and 86Kr¹⁷⁺ beams. Two more ion species, 20Ne⁶⁺ and 129Xe²⁶⁺, have been commissioned on the Front End and delivered to the superconducting linac during the beam commissioning of Linac Segment 1 (LS1) in March 2019. In August 2019, Radio Frequency Quadrupole (RFQ) conditioning reached the full design power of 100 kW continuous wave (CW) that is required to accelerate Ura-nium beams. Start-up/shutdown procedures and opera-tional screens were developed for the Front End subsys-tems for trained operators, and auto-start and RF fast re-covery functions have been implemented for the Front End RFQ and bunchers. In this paper, we will present the current commissioning status of the Front End, and per-formance of the main technical systems, such as the ECR ion source and RFQ.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH06
About •	paper received ※ 01 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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WEPLH07	Commissioning of the FRIB/NSCL New ReA3 4-Rod Radio Frequency Quadrupole Accelerator	817
	S. Nash, J.F. Brandon, D.B. Crisp, T. Summers, A.C.C. Villari, Q. Zhao NSCL, East Lansing, Michigan, USA P.N. Ostroumov, A.S. Plastun FRIB, East Lansing, Michigan, USA
	Funding: This work was supported by the National Science Foundation under Grant PHY-15-65546 The reaccelerator facility ReA3 at the National Superconducting Cyclotron Laboratory is a state-of-the-art accelerator for ions of rare and stable isotopes. The first stage of acceleration is provided by a 4-rod radio-frequency quadrupole (RFQ) at 80.5 MHz, which accelerates ions from 12 keV/u to 530 keV/u. The internal copper acceleration structure of the RFQ was re-designed. The goal was to improve transmission while allowing to operate the RFQ in CW and accelerating ions with A/Q from 2 to 5. In this paper, we summarize the steps involved in the disassembly of the existing structure, preparation work on the retrofitted vacuum vessel, installation of the new components, acceptance testing, and commissioning of the completed RFQ.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH07
About •	paper received ※ 29 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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WEPLH08	Use of the Base-Band Tune Meter Kickers During the FY18 STAR Fixed Target Run at 3.85 GeV/u	820
	P. Adams, N.A. Kling, C. Liu, G.J. Marr BNL, Upton, New York, USA
	The base-band tune meter (BBQ) kickers proved to be a useful tool in managing STAR trigger rates during the RHIC FY18 3.85GeV/u Fixed Target Run. The STAR collected over 3 times their original event goal, since it was possible to optimize the STAR trigger rates throughout the length of the physics store.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH08
About •	paper received ※ 16 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
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WEPLH09	FRIB Driver Linac Integration to be ready for Phased Beam Commissioning	823
	H. Ao, S. Beher, N.K. Bultman, F. Casagrande, C. Compton, J.C. Curtin, K.D. Davidson, K. Elliott, V. Ganni, A. Ganshyn, P.E. Gibson, I. Grender, W. Hartung, L. Hodges, K. Holland, A. Hussain, M. Ikegami, S. Jones, P. Knudsen, S.M. Lidia, G. Machicoane, S.J. Miller, D.G. Morris, P.N. Ostroumov, J.T. Popielarski, L. Popielarski, J. Priller, T. Russo, K. Saito, S. Stanley, D.R. Victory, X. Wang, J. Wei, M. Xu, T. Xu, Y. Yamazaki, S. Zhao FRIB, East Lansing, Michigan, USA A. Facco INFN/LNL, Legnaro (PD), Italy R.E. Laxdal TRIUMF, Vancouver, Canada
	Funding: Work supported by the U.S. Department of Energy (DOE) Office of Science under Cooperative Agreement DE-SC0000661 The driver linac for Facility for Rare Isotope Beams (FRIB) will accelerate all stable ion beams from proton to uranium beyond 200 MeV/u with beam powers up to 400 kW. The linac now consists of 10⁴ superconducting quarter-wave resonators (QWR), which is the world largest number of low-beta SRF cavities operating at an accelerator facility. The first 3 QWR cryomodules (CM) (β = 0.041) were successfully integrated with cryogenics and other support systems for the 2nd Accelerator Readiness Review (ARR). The 3rd ARR scope that includes 11 QWR CM (β=0.085) and 1 QWR matching CM (β=0.085) was commissioned on schedule by January 2019, and then we met the Key Performance Parameters (KPP), accelerating Ar and Kr > 16 MeV/u at this stage, in a week upon the ARR authorization. We examine a variety of key factors to the successful commissioning, such as component testing prior to system integration, assessment steps of system/device readiness, and phased commissioning. This paper also reports on the integration process of the β=0.085 CMs including the test results, and the current progress on β=0.29 and 0.53 CMs in preparation for the upcoming 4th ARR.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH09
About •	paper received ※ 02 September 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLH10	Efficiency Estimation for Sequential Excitation Laser Stripping of H⁻ Beam	827
	T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, Y. Liu, A. Rakhman ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S. Department of Energy. A new laser stripping scheme for charge exchange injection of H⁻ beam is considered. The sequential scheme for the planned demonstration experiment includes two step excitation that requires much smaller laser power compared to the traditional 1-step excitation. The new scheme can be applied to a wider range of H⁻ beam energies and provides more flexibility on the choice of laser frequency. In this paper we discuss the two-step excitation method and estimate laser stripping parameters and stripping efficiency for the SNS accelerator and its future H⁻ energy upgrade to 1.3 GeV.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH10
About •	paper received ※ 22 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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WEPLH11	RHIC Quench Protection Diode Radiation Damage	831
	K.A. Drees, O. Biletskyi, D. Bruno, A. Di Lieto, J. Escallier, G. Heppner, C. Mi, T. Samms, J. Sandberg 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. Each of RHIC’s superconducting magnets is protected by a silicon quench protection diode (QPD). In total, RHIC has over 800 diodes installed inside the cryostat close to the vacuum pipe~[RHICconfig]. After years of operation with high energy heavy ion beams we experienced a first permanently damaged QPD in the middle of our FY2016 Au Au run and a second damaged diode in the following year. In 2016 the run had to be interrupted by 19 days to replace the diode, in 2017 RHIC could still operate with a reduced ramping speed of the superconducting magnets. Both diodes were replaced and examined "cold" as well as "warm". This paper reports on what we have learned so far about the conditions leading up to the damage as well as the damage itself.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH11
About •	paper received ※ 23 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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WEPLH14	Foil Scattering Model for Fermilab Booster
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	C.M. Bhat, S. Chaurize, J.S. Eldred, V.A. Lebedev, S. Nagaitsev, K. Seiya, C.-Y. Tan, R. Tesarek Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored 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. At the Fermilab Booster, and many other proton facilities, an intense proton beam is accumulated by injection an H⁻ beam through a stripping foil. The circulating beam scatters off the injection beam and large-angle Coulomb scattering leads to uncontrolled losses concentrated in the first betatron period. We measure the foil scattering rate in the Booster as a function of linac current, number of injection-turns, and time on injection foil. We find that current Booster operations has a 1% foil scattering loss rate and we make projections for the Proton Improvement Plan II (PIP-II) injector upgrade. We find that accurate modeling of the foil scattering loss must account for beam emittance in conjunction with the scattering rate and ring acceptance. Estimate of beam emittance at injection are discussed.
	Slides WEYBB3 [5.690 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBB3
About •	paper received ※ 28 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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WEPLH15	Light Ion Injector for NICA	834
	H. Höltermann, H. Hähnel, B. Koubek, H. Podlech, U. Ratzinger, A. Schempp, D. Strehl, R. Tiede BEVATECH, Frankfurt, Germany M. Busch, M. Schuett IAP, Frankfurt am Main, Germany A.V. Butenko, D.E. Donets, A.D. Kovalenko, K.A. Levterov, D.A. Lyuosev, A.A. Martynov, D.O. Ponkin, K.V. Shevchenko, I.V. Shirikov, A.O. Sidorin, G.V. Trubnikov JINR/VBLHEP, Dubna, Moscow region, Russia B.V. Golovenskiy, A. Govorov, V.V. Kobets, E. Syresin JINR, Dubna, Moscow Region, Russia
	The Nuclotron ring of the NICA project will get a new light ion injector linac (LILac) for protons and ions with a mass to charge ratio up to 3. The LILac will consist of 2 sections: A 600 A keV RFQ followed by an IH-type DTL up to 7 AMeV, and a postaccelerator IH-cavity for protons only - up to 13 MeV. A switching magnet will additionally allow 13 MeV proton beam injection into a future superconducting testing section. The pulsed Linac up to 7 AMeV and including the postaccelerator for protons up to 13 MeV will be developed in collaboration between JINR and Bevatech GmbH. The technical design of that Linac is discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLH15
About •	paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLH16	Tolerances on Energy Deviation in Microbunched Electron Cooling	837
	P. Baxevanis, G. Stupakov SLAC, Menlo Park, California, USA
	The performance of microbunched electron cooling (MBEC)* is highly dependent on the quality of the hadron and cooler electron beams. As a result, understanding the influence of beam imperfections is very important from the point of view of determining the tolerances of MBEC. In this work, we incorporate a non-zero average energy offset into our 1D formalism (,), which allows us to study the impact of effects such as correlated energy spread (chirp). In particular, we use our analytical theory to calculate the cooling rate loss due to the electron beam chirp and discuss ways to minimize the influence of this effect on MBEC. D. Ratner, Phys. Rev. Lett. 111, 084802 (2013). G. Stupakov, Phys. Rev. AB, 21, 114402 (2018). * G. Stupakov and P. Baxevanis, Phys. Rev. AB, 22, 034401 (2019).
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WEPLH17	Diffusion and Nonlinear Plasma Effects in Microbunched Electron Cooling	841
	P. Baxevanis, G. Stupakov SLAC, Menlo Park, California, USA
	The technique of michrobunched electron cooling (MBEC) is an attractive scheme for enhancing the brightness of hadron beams in future high-energy circular colliders (). To achieve the required cooling times for a realistic machine configuration, it is necessary to boost the bunching of the cooler electron beam through amplification sections that utilize plasma oscillations. However, these plasma sections also amplify the intrinsic noise of the electron beam, leading to additional diffusion that can be very detrimental to the cooling. Moreover, they can exhibit nonlinear gain behavior, which reduces performance and limits the applicability of theory. In this paper, we study both of these important effects analytically with the aim of quantifying their influence and keeping them under control. D. Ratner, Phys. Rev. Lett. 111, 084802 (2013).
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WEPLH18	ELENA Commissioning
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	D. Gamba, M.E. Angoletta, P. Belochitskii, L. Bojtár, F. Butin, C. Carli, B. Dupuy, Y. Dutheil, T. Eriksson, P. Freyermuth, C. Grech, M. Hori, J.R. Hunt, M. Jaussi, L.V. Jørgensen, B. Lefort, S. Pasinelli, L. Ponce, G. Tranquille CERN, Meyrin, Switzerland R. Gebel FZJ, Jülich, Germany C. Grech University of Malta, Information and Communication Technology, Msida, Malta M. Hori MPQ, Garching, Munich, Germany
	The Extra Low ENergy Antiproton storage ring (ELENA) is an upgrade project at the CERN AD (Antiproton Decelerator). ELENA will further decelerate the 5.3 MeV antiprotons coming from the AD down to 100 keV. ELENA features electron cooling for emittance control during deceleration thus preserving the beam intensity and allowing to extract bright bunches towards the experiments. The lower energy will allow for increasing the antiproton trapping efficiency up to two orders of magnitude, which is typically less than 1% with the present beam from AD. The ring was completed with the installation of the electron cooler at the beginning of 2018. Decelerated beams with characteristics close to the design values were obtained before the start of CERN Long Shutdown 2 (LS2). During LS2 electrostatic transfer lines from the ELENA ring to the experimental zones will be installed, replacing the magnetic transfer lines from the AD ring. The latest results of commissioning with H⁻ and antiprotons and the first observation of electron cooling in ELENA will be presented, together with an overview of the project and status and plans for LS2 and beyond.
	Slides WEYBB1 [20.792 MB]
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WEPLH19	Record Fast Cycling Accelerator Magnet Based on High Temperature Superconductor	845
	H. Piekarz, J.N. Blowers, S. Hays, V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	Funding: Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359 We report on the prototype High Temperature Superconductor (HTS) based accelerator magnet capable to operate at 12 T/s B-field ramping rate with a very low supporting cryogenic cooling power thus indicating a feasibility of its application in large accelerator requiring high repetition rate and high average beam power. The magnet is designed to simultaneously accelerate two particle beams in the separate beam gaps energized by a single conductor. The design, construction and the power test arrangement of a prototype of this fast-cycling HTS based accelerator magnet are presented. As example, the cryogenic power loss limit measured in the magnet power test is discussed in terms of feasibility of application of such a magnet for the construction of an 8 GeV dual-beam proton booster accelerator.
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WEPLH20	Modeling of H⁻ Ion Source at LANSCE	848
	N.A. Yampolsky, I. Draganić, L. Rybarcyk LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the US Department of Energy under Contract Number DE-AC52-06NA25396 We report on the progress in modeling performance of the H⁻ ion source at LANSCE. The key aspect we address is the lifetime of the tungsten filament. The lifetime depends on multiple parameters of the ion source and can dramatically vary in different regimes of operation. We use the multiphysics approach to model the performance of the ion source. The detailed analysis has been made to recognize key physical processes, which affect the degradation of the filament. The analysis resulted in the analytical model, which includes relevant processes from the first principles. The numerical code based on this model has been developed and benchmarked. The results of the modeling show good agreement with experimental data. As a result, the developed model allows predicting the performance of the ion source in various regimes of operation.
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Paper

Title

Page

Longitudinal Beam Profile Measurement by Silicon Detector in Facility for Rare Isotope Beams at Michigan State University

799

T. Maruta, P.N. Ostroumov, Q. Zhao
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University
The Facility for Rare Isotope Beams (FRIB) includes a continuous wave superconducting linear accelerator designed to deliver 400 kW ion beams with energies above 200 MeV/u. The beam commissioning of the first three cryomodules took place in the summer of 2018. A temporary diagnostic station installed after the first three cryomodules included a Silicon Detector (SiD) to measure absolute energy and bunch shape of 40Ar and 86Kr beams accelerated up to 2.3 MeV/u. The beam longitudinal emittance was evaluated by measuring bunch shapes while the bunching field amplitude of the upstream resonator was varied. In this paper, we will present the SiD setup and measurement results.

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WEPLH02

Experience with Long-Pulse Operation of the PIP2IT Warm Front End

803

A.V. Shemyakin, J.-P. Carneiro, A.Z. Chen, D. Frolov, B.M. Hanna, R. Neswold, L.R. Prost, G.W. Saewert, A. Saini, V.E. Scarpine, A. Warner, J.Y. Wu
Fermilab, Batavia, Illinois, USA
C.J. Richard
NSCL, East Lansing, Michigan, USA

Funding: This manuscript has been authored 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 warm front end of the PIP2IT accelerator, assembled and commissioned at Fermilab, consists of a 15 mA DC, 30 keV H⁻ ion source, a 2-m long Low Energy Beam Transport (LEBT) line, a 2.1-MeV, 162.5 MHz CW RFQ, followed by a 10-m long Medium Energy Beam Transport (MEBT) line. A part of the commissioning efforts involves operation in regimes where the average beam power in this front end emulates the operation of the proposed PIP-II accelerator, which will have a duty factor of 1.1% or above. The maximum achieved power is 5 kW (2.1 MeV x 5 mA x 25 ms x 20 Hz). This paper describes the difficulties encountered and some of the solutions that were implemented.

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paper received ※ 20 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019

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WEPLH03

Redesign of ReA3 4-Rod RFQ

807

A.S. Plastun, P.N. Ostroumov, A.C.C. Villari, Q. Zhao
FRIB, East Lansing, Michigan, USA
A.C.C. Villari, Q. Zhao
NSCL, East Lansing, Michigan, USA

Funding: Work supported by the U.S. DoE Office of Science under Cooperative Agreement DE-SC0000661 and the NSF under Cooperative Agreement PHY-1102511, the State of Michigan and Michigan State University.
The present RFQ of ReA3 reaccelerator at Michigan State University (MSU) has been commissioned in 2010. This 4-rod RFQ was designed to accelerate the prebunched 80.5 MHz beams with the lowest Q/A = 1/5. However, the lack of proper cooling limited the RFQ performance to the pulsed operation with the lowest Q/A = 1/4. The design voltage for Q/A = 1/5 has never been reached even in a pulsed mode due to the sparking. In 2016 we initiated the upgrade of ReA3 RFQ to support high duty cycle (up to CW) operation with Q/A = 1/5 beams. The upgrade included the new rods with trapezoidal modulation, and new stems with improved cooling. The redesigned 80.5 MHz RFQ will consume only 65% rf power of the present RFQ for Q/A = 1/5 beam. It will provide the transmission up to 78% for 16.1 MHz beams and 89% for 80.5 MHz beams. High reliability and efficiency of the RFQ are very important for the going-on reaccelerator upgrade to ReA6 and for future operation as a part of FRIB. The electrodes have been manufactured and are being installed. The RF and beam tests are scheduled to summer 2019.

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paper received ※ 27 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019

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WEPLH04

Beam Envelope Reconstruction for FRIB-FS1 Transport Line Using Beam Position Monitors

810

T. Yoshimoto, S. Cogan, J.L. Crisp, K. Fukushima, S.M. Lidia, T. Maruta, P.N. Ostroumov, A.S. Plastun, T. Zhang, Q. Zhao
FRIB, East Lansing, Michigan, USA

Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
The Facility for Rare Isotope Beam (FRIB) includes a heavy ion superconducting (SC) linac. Recently we completed beam commissioning of the Linac Segment 1 (LS1) and 45° bend section of the Folding Segment 1 (FS1). Four ion species, 40Ar⁹⁺, 20Ne⁶⁺, 86Kr¹⁷⁺ and 129Xe²⁶⁺ were successfully accelerated to a beam energy of 20.3 MeV/u. We explored the possibility of non-invasive beam diagnostics for online beam envelope monitoring based on beam quadrupole moments derived from Beam Position Monitors (BPMs)*. In future operations, various ion beam species will be accelerated and minimization of beam tuning time is critical. To address this requirement, it is beneficial to use BPMs to obtain beam Twiss parameters instead of wire scanners. This paper reports the results of BPM-based beam Twiss parameters evolution in the FS1.
* R. E. Shafer, "Laser Diagnostic for High Current H beams", Proc. 1998 Beam Instrumentation Workshop (Stanford). A.I.P. Conf. Proceedings, (451), 191.

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paper received ※ 27 August 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019

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WEPLH05

Characterization and Performance of Plasma Window for Gas Flow Restriction in Different Geometries

MOYBB5

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SUPLE17

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A. Lajoie
NSCL, East Lansing, Michigan, USA
J. Gao, F. Marti
FRIB, East Lansing, Michigan, USA

Funding: This work is supported by NSF Award PHY-1565546.
The plasma window is a DC cascaded arc whose function is to restrict gas flow from a high pressure region to a low pressure region without the use of any solid separation*. As a result, the plasma window allows a greater pressure to be maintained than otherwise possible. This is a beneficial characteristic for gas charge strippers for ion accelerators, since the higher pressures enable the stripper to be shorter and allow the same amount of stripping interactions**. The flow rate reduction is established by the increase in gas temperature from the power deposited into the plasma via the cathodes, resulting in a dramatically increased viscosity. The flow rate reduction, depends on the properties of the plasma, including the electron density and temperature, pressure, and electrical conductivity. Understanding these properties in multiple arc geometries - in this work having either 6 mm or 10 mm channel diameter - provides a means optimizing the plasma window for a given design. Determinations of the properties for different conditions are shown, and results are compared with a PLASIMO simulation, which has been shown to yield comparable properties to measurements in an argon arc***.
*A. Hershcovitch, Phys. Plasma 5, 2130 (1998).
**J. A. Nolen and F. Marti, Rev. Accel. Sci. Tech. 6, 221 (2013).
***G. M. W. Kroesen et al., Plas. Chem. and Plas. Proc. 10, 531 (1990).

Slides MOYBB5 [4.132 MB]

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

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WEPLH06

Commissioning Status of the FRIB Front End

813

H.T. Ren, J. Brandon, N.K. Bultman, K.D. Davidson, E. Daykin, T. Elkin, B. Galecka, P.E. Gibson, L. Hodges, K. Holland, D.D. Jager, M.G. Konrad, B.R. Kortum, S.M. Lidia, G. Machicoane, I.M. Malloch, H. Maniar, T. Maruta, G. Morgan, D.G. Morris, P. Morrison, A.C. Morton, P.N. Ostroumov, A.S. Plastun, E. Pozdeyev, X. Rao, T. Russo, J.W. Stetson, R. Walker, J. Wei, Y. Yamazaki, T. Yoshimoto, Q. Zhao, S. Zhao
FRIB, East Lansing, Michigan, USA
S. Renteria
NSCL, East Lansing, Michigan, USA

Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The FRIB Front End was successfully commissioned in 2017 with commissioning goals achieved and Key Per-formance Parameters (KPP) demonstrated for both 40Ar⁹⁺ and 86Kr¹⁷⁺ beams. Two more ion species, 20Ne⁶⁺ and 129Xe²⁶⁺, have been commissioned on the Front End and delivered to the superconducting linac during the beam commissioning of Linac Segment 1 (LS1) in March 2019. In August 2019, Radio Frequency Quadrupole (RFQ) conditioning reached the full design power of 100 kW continuous wave (CW) that is required to accelerate Ura-nium beams. Start-up/shutdown procedures and opera-tional screens were developed for the Front End subsys-tems for trained operators, and auto-start and RF fast re-covery functions have been implemented for the Front End RFQ and bunchers. In this paper, we will present the current commissioning status of the Front End, and per-formance of the main technical systems, such as the ECR ion source and RFQ.

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WEPLH07

Commissioning of the FRIB/NSCL New ReA3 4-Rod Radio Frequency Quadrupole Accelerator

817

S. Nash, J.F. Brandon, D.B. Crisp, T. Summers, A.C.C. Villari, Q. Zhao
NSCL, East Lansing, Michigan, USA
P.N. Ostroumov, A.S. Plastun
FRIB, East Lansing, Michigan, USA

Funding: This work was supported by the National Science Foundation under Grant PHY-15-65546
The reaccelerator facility ReA3 at the National Superconducting Cyclotron Laboratory is a state-of-the-art accelerator for ions of rare and stable isotopes. The first stage of acceleration is provided by a 4-rod radio-frequency quadrupole (RFQ) at 80.5 MHz, which accelerates ions from 12 keV/u to 530 keV/u. The internal copper acceleration structure of the RFQ was re-designed. The goal was to improve transmission while allowing to operate the RFQ in CW and accelerating ions with A/Q from 2 to 5. In this paper, we summarize the steps involved in the disassembly of the existing structure, preparation work on the retrofitted vacuum vessel, installation of the new components, acceptance testing, and commissioning of the completed RFQ.

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paper received ※ 29 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019

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WEPLH08

Use of the Base-Band Tune Meter Kickers During the FY18 STAR Fixed Target Run at 3.85 GeV/u

820

P. Adams, N.A. Kling, C. Liu, G.J. Marr
BNL, Upton, New York, USA

The base-band tune meter (BBQ) kickers proved to be a useful tool in managing STAR trigger rates during the RHIC FY18 3.85GeV/u Fixed Target Run. The STAR collected over 3 times their original event goal, since it was possible to optimize the STAR trigger rates throughout the length of the physics store.

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paper received ※ 16 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

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WEPLH09

FRIB Driver Linac Integration to be ready for Phased Beam Commissioning

823

H. Ao, S. Beher, N.K. Bultman, F. Casagrande, C. Compton, J.C. Curtin, K.D. Davidson, K. Elliott, V. Ganni, A. Ganshyn, P.E. Gibson, I. Grender, W. Hartung, L. Hodges, K. Holland, A. Hussain, M. Ikegami, S. Jones, P. Knudsen, S.M. Lidia, G. Machicoane, S.J. Miller, D.G. Morris, P.N. Ostroumov, J.T. Popielarski, L. Popielarski, J. Priller, T. Russo, K. Saito, S. Stanley, D.R. Victory, X. Wang, J. Wei, M. Xu, T. Xu, Y. Yamazaki, S. Zhao
FRIB, East Lansing, Michigan, USA
A. Facco
INFN/LNL, Legnaro (PD), Italy
R.E. Laxdal
TRIUMF, Vancouver, Canada

Funding: Work supported by the U.S. Department of Energy (DOE) Office of Science under Cooperative Agreement DE-SC0000661
The driver linac for Facility for Rare Isotope Beams (FRIB) will accelerate all stable ion beams from proton to uranium beyond 200 MeV/u with beam powers up to 400 kW. The linac now consists of 10⁴ superconducting quarter-wave resonators (QWR), which is the world largest number of low-beta SRF cavities operating at an accelerator facility. The first 3 QWR cryomodules (CM) (β = 0.041) were successfully integrated with cryogenics and other support systems for the 2nd Accelerator Readiness Review (ARR). The 3rd ARR scope that includes 11 QWR CM (β=0.085) and 1 QWR matching CM (β=0.085) was commissioned on schedule by January 2019, and then we met the Key Performance Parameters (KPP), accelerating Ar and Kr > 16 MeV/u at this stage, in a week upon the ARR authorization. We examine a variety of key factors to the successful commissioning, such as component testing prior to system integration, assessment steps of system/device readiness, and phased commissioning. This paper also reports on the integration process of the β=0.085 CMs including the test results, and the current progress on β=0.29 and 0.53 CMs in preparation for the upcoming 4th ARR.

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WEPLH10

Efficiency Estimation for Sequential Excitation Laser Stripping of H⁻ Beam

827

T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, Y. Liu, A. Rakhman
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S. Department of Energy.
A new laser stripping scheme for charge exchange injection of H⁻ beam is considered. The sequential scheme for the planned demonstration experiment includes two step excitation that requires much smaller laser power compared to the traditional 1-step excitation. The new scheme can be applied to a wider range of H⁻ beam energies and provides more flexibility on the choice of laser frequency. In this paper we discuss the two-step excitation method and estimate laser stripping parameters and stripping efficiency for the SNS accelerator and its future H⁻ energy upgrade to 1.3 GeV.

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paper received ※ 22 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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WEPLH11

RHIC Quench Protection Diode Radiation Damage

831

K.A. Drees, O. Biletskyi, D. Bruno, A. Di Lieto, J. Escallier, G. Heppner, C. Mi, T. Samms, J. Sandberg
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.
Each of RHIC’s superconducting magnets is protected by a silicon quench protection diode (QPD). In total, RHIC has over 800 diodes installed inside the cryostat close to the vacuum pipe~[RHICconfig]. After years of operation with high energy heavy ion beams we experienced a first permanently damaged QPD in the middle of our FY2016 Au Au run and a second damaged diode in the following year. In 2016 the run had to be interrupted by 19 days to replace the diode, in 2017 RHIC could still operate with a reduced ramping speed of the superconducting magnets. Both diodes were replaced and examined "cold" as well as "warm". This paper reports on what we have learned so far about the conditions leading up to the damage as well as the damage itself.

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paper received ※ 23 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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WEPLH14

Foil Scattering Model for Fermilab Booster

WEYBB3

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C.M. Bhat, S. Chaurize, J.S. Eldred, V.A. Lebedev, S. Nagaitsev, K. Seiya, C.-Y. Tan, R. Tesarek
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored 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.
At the Fermilab Booster, and many other proton facilities, an intense proton beam is accumulated by injection an H⁻ beam through a stripping foil. The circulating beam scatters off the injection beam and large-angle Coulomb scattering leads to uncontrolled losses concentrated in the first betatron period. We measure the foil scattering rate in the Booster as a function of linac current, number of injection-turns, and time on injection foil. We find that current Booster operations has a 1% foil scattering loss rate and we make projections for the Proton Improvement Plan II (PIP-II) injector upgrade. We find that accurate modeling of the foil scattering loss must account for beam emittance in conjunction with the scattering rate and ring acceptance. Estimate of beam emittance at injection are discussed.

Slides WEYBB3 [5.690 MB]

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WEPLH15

Light Ion Injector for NICA

834

H. Höltermann, H. Hähnel, B. Koubek, H. Podlech, U. Ratzinger, A. Schempp, D. Strehl, R. Tiede
BEVATECH, Frankfurt, Germany
M. Busch, M. Schuett
IAP, Frankfurt am Main, Germany
A.V. Butenko, D.E. Donets, A.D. Kovalenko, K.A. Levterov, D.A. Lyuosev, A.A. Martynov, D.O. Ponkin, K.V. Shevchenko, I.V. Shirikov, A.O. Sidorin, G.V. Trubnikov
JINR/VBLHEP, Dubna, Moscow region, Russia
B.V. Golovenskiy, A. Govorov, V.V. Kobets, E. Syresin
JINR, Dubna, Moscow Region, Russia

The Nuclotron ring of the NICA project will get a new light ion injector linac (LILac) for protons and ions with a mass to charge ratio up to 3. The LILac will consist of 2 sections: A 600 A keV RFQ followed by an IH-type DTL up to 7 AMeV, and a postaccelerator IH-cavity for protons only - up to 13 MeV. A switching magnet will additionally allow 13 MeV proton beam injection into a future superconducting testing section. The pulsed Linac up to 7 AMeV and including the postaccelerator for protons up to 13 MeV will be developed in collaboration between JINR and Bevatech GmbH. The technical design of that Linac is discussed in this paper.

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paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEPLH16

Tolerances on Energy Deviation in Microbunched Electron Cooling

837

P. Baxevanis, G. Stupakov
SLAC, Menlo Park, California, USA

The performance of microbunched electron cooling (MBEC)* is highly dependent on the quality of the hadron and cooler electron beams. As a result, understanding the influence of beam imperfections is very important from the point of view of determining the tolerances of MBEC. In this work, we incorporate a non-zero average energy offset into our 1D formalism (**,***), which allows us to study the impact of effects such as correlated energy spread (chirp). In particular, we use our analytical theory to calculate the cooling rate loss due to the electron beam chirp and discuss ways to minimize the influence of this effect on MBEC.
* D. Ratner, Phys. Rev. Lett. 111, 084802 (2013).
** G. Stupakov, Phys. Rev. AB, 21, 114402 (2018).
*** G. Stupakov and P. Baxevanis, Phys. Rev. AB, 22, 034401 (2019).

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paper received ※ 28 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEPLH17

Diffusion and Nonlinear Plasma Effects in Microbunched Electron Cooling

841

P. Baxevanis, G. Stupakov
SLAC, Menlo Park, California, USA

The technique of michrobunched electron cooling (MBEC) is an attractive scheme for enhancing the brightness of hadron beams in future high-energy circular colliders (*). To achieve the required cooling times for a realistic machine configuration, it is necessary to boost the bunching of the cooler electron beam through amplification sections that utilize plasma oscillations. However, these plasma sections also amplify the intrinsic noise of the electron beam, leading to additional diffusion that can be very detrimental to the cooling. Moreover, they can exhibit nonlinear gain behavior, which reduces performance and limits the applicability of theory. In this paper, we study both of these important effects analytically with the aim of quantifying their influence and keeping them under control.
* D. Ratner, Phys. Rev. Lett. 111, 084802 (2013).

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WEPLH18

ELENA Commissioning

WEYBB1

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D. Gamba, M.E. Angoletta, P. Belochitskii, L. Bojtár, F. Butin, C. Carli, B. Dupuy, Y. Dutheil, T. Eriksson, P. Freyermuth, C. Grech, M. Hori, J.R. Hunt, M. Jaussi, L.V. Jørgensen, B. Lefort, S. Pasinelli, L. Ponce, G. Tranquille
CERN, Meyrin, Switzerland
R. Gebel
FZJ, Jülich, Germany
C. Grech
University of Malta, Information and Communication Technology, Msida, Malta
M. Hori
MPQ, Garching, Munich, Germany

The Extra Low ENergy Antiproton storage ring (ELENA) is an upgrade project at the CERN AD (Antiproton Decelerator). ELENA will further decelerate the 5.3 MeV antiprotons coming from the AD down to 100 keV. ELENA features electron cooling for emittance control during deceleration thus preserving the beam intensity and allowing to extract bright bunches towards the experiments. The lower energy will allow for increasing the antiproton trapping efficiency up to two orders of magnitude, which is typically less than 1% with the present beam from AD. The ring was completed with the installation of the electron cooler at the beginning of 2018. Decelerated beams with characteristics close to the design values were obtained before the start of CERN Long Shutdown 2 (LS2). During LS2 electrostatic transfer lines from the ELENA ring to the experimental zones will be installed, replacing the magnetic transfer lines from the AD ring. The latest results of commissioning with H⁻ and antiprotons and the first observation of electron cooling in ELENA will be presented, together with an overview of the project and status and plans for LS2 and beyond.

Slides WEYBB1 [20.792 MB]

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WEPLH19

Record Fast Cycling Accelerator Magnet Based on High Temperature Superconductor

845

H. Piekarz, J.N. Blowers, S. Hays, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

Funding: Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359
We report on the prototype High Temperature Superconductor (HTS) based accelerator magnet capable to operate at 12 T/s B-field ramping rate with a very low supporting cryogenic cooling power thus indicating a feasibility of its application in large accelerator requiring high repetition rate and high average beam power. The magnet is designed to simultaneously accelerate two particle beams in the separate beam gaps energized by a single conductor. The design, construction and the power test arrangement of a prototype of this fast-cycling HTS based accelerator magnet are presented. As example, the cryogenic power loss limit measured in the magnet power test is discussed in terms of feasibility of application of such a magnet for the construction of an 8 GeV dual-beam proton booster accelerator.

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WEPLH20

Modeling of H⁻ Ion Source at LANSCE

848

N.A. Yampolsky, I. Draganić, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the US Department of Energy under Contract Number DE-AC52-06NA25396
We report on the progress in modeling performance of the H⁻ ion source at LANSCE. The key aspect we address is the lifetime of the tungsten filament. The lifetime depends on multiple parameters of the ion source and can dramatically vary in different regimes of operation. We use the multiphysics approach to model the performance of the ion source. The detailed analysis has been made to recognize key physical processes, which affect the degradation of the filament. The analysis resulted in the analytical model, which includes relevant processes from the first principles. The numerical code based on this model has been developed and benchmarked. The results of the modeling show good agreement with experimental data. As a result, the developed model allows predicting the performance of the ion source in various regimes of operation.

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