Speaker
Joshua Magee
(College of William and Mary)
Description
Modern electron scattering experiments, and in particular those utilizing
parity-violating electron scattering, require precise knowledge of electron beam
polarization. Recently at Jefferson Lab Hall C, sub-percent beam polarization
determination was achieved during the Q-weak experiment using two independent
polarimeters. The Hall C Moller uses a pure iron foil that is driven into
magnetic saturation out-of-plane by a high (3.5 T) field superconducting
solenoid. A Compton polarimeter was installed in 2010 which uses a 532 nm VERDI
laser. Both recoil electron and backscattered photon are detected enabling a
semi-independent determination of beam polarization. Results from the Q-weak
Run 2 period shows both Moller and Compton electron detector achieved
sub-percent precision, and agree to within 0.7%. An independent Moller-Compton
cross-calibration was also performed. This talk will introduce both Hall C
polarimeters, their systematics, and the cross-calibration results, using
Q-weak's $2^{nd}$ run period as an example.
Primary author
Joshua Magee
(College of William and Mary)
