PRECISE POLARIZATION MEASUREMENTS VIA DETECTION OF COMPTON SCATTERED ELECTRONS

摘要

The Qweak experiment at Jefferson Lab aims to make a 4％ measurement of the parity-violating asymmetry in elastic scattering at very low Q~2 of a longitudinally polarized electron beam off a proton target. One of the dominant experimental systematic uncertainties in Qweak will result from determining the beam polarization. A new Compton polarimeter was installed in the fall of 2010 io provide a noninvasive and continuous monitoring of the electron beam polarization in Hall C at Jefferson Lab. The Compton-scattered electrons are detected in four planes of diamond microstrip detectors. We have achieved the design goals of ＜ 1％ statistical uncertainty per hour and expect to achieve ≤ 1％ systematic uncertainty.