Measuring the proton beam polarization

Polarimeters are necessary tools for measuring and maintaining the beam polarization during the acceleration process. They serve, as well, as a yardstick for performing spin physics experiments. In this paper, I will describe the principles of measuring proton beam polarization and the techniques that are employed at various energies. I will use as a guide the design work for the Polarized Proton Project at the Relativistic Heavy Ion Collider (RHIC) which is under construction at Brookhaven National Laboratory.