Author: Derbenev, Y.S.
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WEPMW012 Injection Optics for the JLEIC Ion Collider Ring 2445
 
  • V.S. Morozov, Y.S. Derbenev, F. Lin, F.C. Pilat, G.H. Wei, Y. Zhang
    JLab, Newport News, Virginia, USA
  • Y. Cai, Y. Nosochkov, M.K. Sullivan, M.-H. Wang
    SLAC, Menlo Park, California, USA
 
  Funding: * Work supported by the U.S. DOE Contract DE-AC02-76SF00515. ** Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The Jefferson Lab Electron-Ion Collider (JLEIC) will accelerate protons and ions from 8 GeV to 100 GeV. A very low beta function at the Interaction Point (IP) is needed to achieve the required luminosity. One consequence of the low beta optics is that the beta function in the final focusing (FF) quadrupoles is extremely high. This leads to a large beam size in these magnets as well as strong sensitivity to errors which limits the dynamic aperture. These effects are stronger at injection energy where the beam size is maximum, and therefore very large aperture FF magnets are required to allow a large dynamic aperture. A standard solution is a relaxed injection optics with IP beta function large enough to provide a reasonable FF aperture. This also reduces the effects of FF errors resulting in a larger dynamic aperture at injection. We describe the ion ring injection optics design as well as a beta-squeeze transition from the injection to collision optics.
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW012  
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WEPMW016 Towards a Small Emittance Design of the JLEIC Electron Collider Ring 2457
 
  • F. Lin, Y.S. Derbenev, A. Hutton, V.S. Morozov, F.C. Pilat, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The electron collider ring of the Jefferson Lab Electron-Ion Collider (JLEIC) is designed to provide an electron beam with a small beam size at the IP for collisions with an ion beam in order to reach a desired high luminosity. For a chosen beta-star at the IP, electron beam size is determined by the equilibrium emittance that can be obtained through a linear optics design. This paper briefly describes the baseline design of the electron collider ring reusing PEP-II components and considering their parameters (such as dipole sagitta, magnet field strengths and acceptable synchrotron radiation power) and reports a few approaches to reducing the equilibrium emittance in the electron collider ring.
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW016  
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WEPMW017 Ion Beam Polarization Dynamics in the 8 Gev Booster of the Jleic Project at Jlab 2460
 
  • V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
    JLab, Newport News, Virginia, USA
  • Y. Filatov
    MIPT, Dolgoprudniy, Moscow Region, Russia
  • A.M. Kondratenko, M.A. Kondratenko
    Science and Technique Laboratory Zaryad, Novosibirsk, Russia
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
In the Jefferson Lab's Electron-Ion Collider (JLEIC) project, an injector of polarized ions into the collider ring is a superconducting 8 GeV booster. Both figure-8 and racetrack booster versions were considered. Our analysis showed that the figure-8 ring configuration allows one to preserve the polarization of any ion species during beam acceleration using only small longitudinal field with an integral less than 0.5 Tm. In the racetrack booster, to preserve the polarization of ions with the exception of deuterons, it suffices to use a solenoidal Siberian snake with a maximum field integral of 30 Tm. To preserve deuteron polarization, we propose to use arc magnets for the race-track booster structure with a field ramp rate of the order of 1 T/s. We calculate deuteron and proton beam polarizations in both the figure-8 and racetrack boosters including alignment errors of their magnetic elements using the Zgoubi code.
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW017  
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WEPMW019 Study of Beam Synchronization at JLEIC 2463
 
  • V.S. Morozov, Y.S. Derbenev, J. Guo, A. Hutton, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The ion collider ring of Jefferson Lab's Electron-Ion Collider (JLEIC) accommodates a wide range of ion energies, from 20 to 100 GeV for protons or from 8 to 40 GeV per nucleon for lead ions. In this medium energy range, ions are not fully relativistic, which means values of their relativistic beta are slightly below 1, leading to an energy dependence of revolution time of the collider ring. On the other hand, electrons with energy 3 GeV and above are already ultra-relativistic such that their speeds are effectively equal to the speed of light. The difference in speeds of colliding electrons and ions in JLEIC, when translated into a path-length difference necessary to maintain the same timing between electron and ion bunches, is quite large. In this paper, we explore schemes for synchronizing the electron and ion bunches at a collision point as the ion energy is varied.
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW019  
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WEPMW020 Storage-ring Electron Cooler for Relativistic Ion Beams 2466
 
  • F. Lin, Y.S. Derbenev, D. Douglas, J. Guo, G.A. Krafft, V.S. Morozov, Y. Zhang
    JLab, Newport News, Virginia, USA
  • R.P. Johnson
    Muons, Inc, Illinois, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357
Application of electron cooling at ion energies above a few GeV has been limited due to reduction of electron cooling efficiency with energy and difficulty in producing and accelerating a high-current high-quality electron beam. A high-current storage-ring electron cooler offers a solution to both of these problems by maintaining high cooling beam quality through naturally-occurring synchrotron radiation damping of the electron beam. However, the range of ion energies where storage-ring electron cooling can be used has been limited by low electron beam damping rates at low ion energies and high equilibrium electron energy spread at high ion energies. This paper reports a development of a storage ring based cooler consisting of two sections with significantly different energies: the cooling and damping sections. The electron energy and other parameters in the cooling section are adjusted for optimum cooling of a stored ion beam. The beam parameters in the damping section are adjusted for optimum damping of the electron beam. The necessary energy difference is provided by an energy recovering SRF structure. A prototype linear optics of such storage-ring cooler is presented.
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW020  
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