Direct Comparison of M\o ller and Compton Polarimeters in Hall C at Jefferson Lab

Conference · Sun Jan 01 00:00:00 EST 2017

DOI:https://doi.org/10.2172/1985259· OSTI ID:1985259

Gaskell, David ^[1]

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1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

Knowledge of the electron beam polarization is one of the most important systematic uncertainties in precision, parity-violating electron scattering experiments with next generation experiments aiming to measure the electron beam polarization to better than 0.5\%. At high energies, the most typical polarimetry techniques are M\o ller (polarized electron-electron) and Compton (polarized electron-photon) scattering. The use of two techniques with different systematic uncertainties provides confidence in the extracted beam polarization. Direct comparisons of the two polarimetry techniques are challenging in that Compton polarimeters typically desire maximum beam flux (high beam currents) while M\o ller polarimeters need to limit the beam current to avoid depolarization effects in the target. We have performed a direct comparison of the M\o ller and Compton polarimeters in experimental Hall C at Jefferson Lab. This test is unique in that the data were taken sequentially under identical beam conditions at ?4.5~?A. We found excellent agreement between the Hall C M\o ller and Compton polarimeters. Combined with high-current Compton data, we were also able to limit the beam current dependence of the beam polarization to 1\% or less up to a beam current of 180~?A.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1985259
• Report Number(s): JLAB-PHY-17-2675; DOE/OR/23177-6409
• Resource Relation: Conference: APS April Meeting 2017, January 28–31, 2017; Washington, DC
• Country of Publication: United States
• Language: English