Polarized proton acceleration at the KEK PS

Research and development of polarized proton beam acceleration is being carried out at the KEK (Japan National Laboratory for High-Energy Physics) PS (proton synchrotron), and approximately 40% and 25% polarization has been obtained at 3.5 GeV and 5.0 GeV, respectively, in the main ring. The performance of the polarized proton beam acceleration and the origin of the depolarization in the booster are described. For the booster, about 75% of the linac beam polarization has been preserved at 500 MeV during normal polarized beam operation. If the pulsed sextupole for manipulation of the chromaticity is constructed, polarization at 500 MeV is expected to be around 90-95% of the linac beam polarization. The polarizations at various energies obtained so far in the accelerator are 60-65% at 20 MeV, 45-55% at 500 MeV, 34-40% at 3.5 GeV, and 25% at 5.0 GeV. As a preliminary result, about 8% polarization was obtained at 7.6 GeV. Accelerated beam intensity is 0.9×10¹⁰ p.p.p. at 3.5 GeV