NAPAC2022 - List of Keywords (polarization)

Paper	Title	Other Keywords	Page
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 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

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 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

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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 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

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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 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

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)