A p-carbon CNI polarimeter for RHIC

The RHIC spin program requires excellent polarimetry so that the knowledge of the beam polarization does not limit the errors on the experimental measurements. However, polarimetry of proton beams with energies higher than about 30 GeV poses a difficult challenge. For polarization monitoring during operation, a fast and reliable polarimeter is required that produces a polarization measurement with a 10% relative error within a few minutes. The p-carbon elastic scattering in the Coulomb-nuclear-scattering (CNI) region has a calculable and large analyzing power, but detecting the recoil carbon needs a sophisticated detector system and a very thin target. An experiment has been planned in the AGS. This paper describes the experimental setup in the AGS.