p‐Carbon Polarimetry at RHIC

The polarization measurement through elastic (p,C) reaction plays a crucial role in the polarized proton beam operation of Relativistic Heavy Ion collider at Brookhaven National Laboratory. As well as measuring the polarization, the unknown analyzing power AN of elastic (p,C) is determined as well in combination with the absolute polarization meausement by a H‐jet polarimeter. The systematic uncertainty of the Run05 measurements are discussed as well as introducing the experimental apparatus of the polarimeter system.