Depolarizing Resonance Correction in Polarized Proton Beam Acceleration up to 5.0 GeV at the KEK PS

Abstract

The research and development of polarized proton acceleration is being carried out at the KEK 12 GeV proton synchrotron. This paper describes the phenomena encountered in accelerating a polarized proton beam up to 5.0 GeV. Besides conventional methods for correcting depolarizing resonance, an adiabatic resonance crossing with pulsed quadruple magnets has been successfully applied to correct strong intrinsic resonances. At present, 90% of the linac polarization has been preserved in the booster synchrotron with reduced accelerating rf voltage to avoid the depolarization by synchrotron oscillation. In the main ring, 90% and 50% of the booster beam polarization was preserved at 3.5 GeV and 5.0 GeV, respectively. The KEK PS is the first cascaded synchrotron which has demonstrated a polarized proton beam.