PHENIX Local Polarimetry Analysis

Abstract

In PHENIX experiment, one of the most important goals is to study proton spin structure through spin asymmetry measurements of various production cross sections from polarized proton-proton collisions. In 2013, we had longitudinally polarized proton-proton collisions. The gluon contribution to the proton Delta G measurement through longitudinal double spin asymmetry A_LL measurement has been done. Since one of the main systematic uncertainty of A_LL comes from transverse component of beam polarization, its measurement is very important. In order to measure transverse component of beam polarization at the collision point in the PHENIX interaction area, a subsystem called local polarimeter is used by using A_N of forward neutron production. It turned out that, transverse component of longitudinally polarized beam during the experiment does not signicantly contribute systematic error in A_LL measurement.