Internal Polarimeters for the Polarized Proton Beam at the KEK 12 GeV PS

An internal polarimeter was constructed to detect the beam polarization in KEK proton synchrotron (PS) from TP = 500 MeV to 12 GeV. The polarimeter was installed in the main ring and successfully used for the measurement of the beam polarization at 500 MeV. We report the design and the performance of this polarimeter and the results of this first measurement. In addition to that, we also report the design of another internal polarimeter for monitoring the depolarization in the booster.