Changes in detection characteristics of CdTe X-ray sensors by proton irradiation

This paper reports on the performance changes in CdTe:Cl semiconductor X-ray detectors seen after irradiation with 50 MeV protons up to a fluence of 1.6⋅1011cm−2. The rationale for the irradiation parameters is described. Performance was quantified before and after irradiations by obtaining X-ray spectra with a barium-133 radioactive source and detectors cooled to −20°C. Energy resolutions, electron and hole drift lengths, and energy calibration parameters were extracted by fitting model spectra to the data. Ten crystals of dimension 10×10×1 mm3 were used, with two each being irradiated to 20%, 40%, 60%, 80%, and 100% of the maximum fluence. Each crystal is pixelized and the eight large pixels of area 9.6mm2 are analysed separately to allow estimation of uncertainties.