Proton irradiation on p-bulk silicon strip detectors using 12 GeV PS at KEK

P-bulk n-strip silicon strip detectors were irradiated with a 12 GeV proton beam at the KEK Proton Synchrotron in order to investigate a radiation damage due to high fluence of high energy protons. Primary 12 GeV protons extracted at the EP1-A beam line was used for the irradiation. The detectors were irradiated with the fluences of 1.1 × 1014 and 4.3 × 1013 protons/cm2 for the high and low fluence exposures, respectively. Bias voltage for achieving the full depletion of the irradiated p-bulk detectors was observed to be significantly higher than that for the n-bulk detectors. The full depletion voltage did not increase monotonically as the fluence increased; it showed little variation up to about 5 × 1013 p/cm2 and then started to increase. The behaviour could be explained by assuming a contribution from three processes: effective acceptor creation, persistent acceptor component, and acceptor removal.