THE EFFECTS OF 199 MEV PROTON RADIATION-DAMAGE ON CDZNTE PHOTON DETECTORS

Four CdZnTe detectors were irradiated with 199 MeV protons to simulate the damaging radiation in space. The gamma-ray spectra of Am-241 and Co-57 as well as the detector leakage currents were monitored at room temperature to assess the effects of radiation damage. Surprisingly, a fter a fluence of a few x 10(8) p/cm(2) gamma-ray peak shifts and reso lution degradation became visible. After a fluence of 5x10(9) p/cm(2) the degradation was quite dramatic. An analysis of these effects dearl y demonstrates that radiation damage causes electron trapping in CdZnT e detectors. No increase in leakage current or electronic noise was ob served. Radiation damage effects in CdZnTe and germanium detectors are compared. CdZnTe detectors are similar to 250 times more sensitive to radiation damage than germanium detectors per unit charge-drift dista nce.