Keyword: polarization
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MOYE6 Spin-Polarized Electron Photoemission and Detection Studies electron, experiment, simulation, cathode 26
  • A.C. Rodriguez Alicea, R. Palai
    University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico
  • O. Chubenko, S.S. Karkare
    Arizona State University, Tempe, USA
  • L. Cultrera
    BNL, Upton, New York, USA
  Funding: Brookhaven National Laboratory and the Department of Energy of United States under contract No. DE-SC0012704 Also, the Center for Bright Beams, NSF award PHY-1549132.
The experimental investigation of new photocathode ma- terials is time-consuming, expensive, and difficult to accom- plish. Computational modelling offers fast and inexpensive ways to explore new materials, and operating conditions, that could potentially enhance the efficiency of polarized electron beam photocathodes. We report on Monte-Carlo simulation of electron spin polarization (ESP) and quantum efficiency (QE) of bulk GaAs at 2, 77, and 300 K using the data obtained from Density Functional Theory (DFT) cal- culations at the corresponding temperatures. The simulated results of ESP and QE were compared with reported exper- imental measurements, and showed good agreement at 77 and 300 K.
slides icon Slides MOYE6 [6.235 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE6  
About • Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 04 September 2022
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TUPA14 Fast First-Order Spin Propagation for Spin Matching and Polarization Optimization with Bmad quadrupole, lattice, solenoid, electron 369
  • J.M. Asimow, G.H. Hoffstaetter, D. Sagan, M.G. Signorelli
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  Accurate spin tracking is essential for the simulation and propagation of polarized beams, in which a majority of the particles’ spin point in the same direction. Bmad, an open-sourced library for the simulation of charged particle dynamics, traditionally tracks spin via integrating through each element of a lattice. While exceptionally accurate, this method has the drawback of being slow; at best, the runtime is proportional to the length of the element. By solving the spin transport equation for simple magnet elements, Bmad can reduce this algorithm to constant runtime while maintaining high accuracy. This method, known as "Sprint," enables quicker spin matching and prototyping of lattice designs via Bmad.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA14  
About • Received ※ 30 July 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 August 2022
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WEPA22 Measuring the Electric Dipole Moment of the Electron in a Two-Energy Spin-Transparent Storage Ring electron, dipole, storage-ring, experiment 665
  • R. Suleiman, Y.S. Derbenev
    JLab, Newport News, Virginia, USA
  • V.S. Morozov
    ORNL RAD, Oak Ridge, Tennessee, USA
  Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and by UT-Battelle, LLC, under contract DE-AC05-00OR22725.
We will present a new design of a two-energy storage ring for low energy (0.2 to 2 MeV) polarized electron bunches [1]. The new design is based on the transparent spin methodology that cancels the spin precession due to the magnetic dipole moment at any energy while allowing for spin precession induced by the fundamental physics of interest to accumulate. The buildup of the vertical component of beam polarization can be measured using standard Mott polarimetry that is optimal at low electron energy. These rings can be used to measure the permanent electric dipole moment of the electron, relevant to CP violation and matter-antimatter asymmetry in the universe, and to search for dark energy and ultra-light dark matter.
[1] R. Suleiman, V.S. Morozov, and Y.S. Derbenev, On possibilities of high precision experiments in fundamental physics in storage rings of low energy polarized electron beams, arXiv:2105.11575 (2021)
poster icon Poster WEPA22 [0.781 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA22  
About • Received ※ 04 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 07 October 2022
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WEPA68 Record Quantum Efficiency from Superlattice Photocathode for Spin Polarized Electron Beam Production electron, cathode, lattice, distributed 784
  • J.P. Biswas, L. Cultrera, K. Kisslinger, W. Liu, J. Skarita, E. Wang
    BNL, Upton, New York, USA
  • S.D. Hawkins, J.F. Klem, S.R. Lee
    Sandia National Laboratories, Albuquerque, New Mexico, USA
  Funding: The work is supported by Brookhaven Science Associates, LLC under Contract DESC0012704 with the U.S. DOE. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
Electron sources producing highly spin-polarized electron beams are currently possible only with photocathodes based on GaAs and other III-V semiconductors. GaAs/GaAsP superlattice (SL) photocathodes with a distributed Bragg reflector (DBR) represent the state of the art for the production of spin-polarized electrons. We present results on a SL-DBR GaAs/GaAsP structure designed to leverage strain compensation to achieve simultaneously high QE and spin polarization. These photocathode structures were grown using molecular beam epitaxy and achieved quantum efficiencies exceeding 15% and electron spin polarization of about 75% when illuminated with near bandgap photon energies.
poster icon Poster WEPA68 [4.506 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA68  
About • Received ※ 20 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 10 August 2022
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