Effect of fast neutron irradiation on CdTe radiation detectors

The influence of fast neutron irradiation was studied for CdTe radiation detectors in the range of fluence 1.0 x 10(8)-1.8 x 10(11)n/cm(2). The effect of gamma-ray heavy irradiation toward the detector was also investigated for the comparison. Americium-241 and Cs-137 gamma-ray spectra measured before and after irradiation were compared to examine the change of the detector performance. A pulse height and a rise time of a radiation signal were simultaneously measured in order to evaluate the transport property of both electrons and holes. Peak shift. toward lower energies was observed in the Am-241 gamma-ray spectrum after fast neutron irradiation. Electron mu tau product showed large decrease with increasing the neutron fluence, while the one for holes remained unchanged. For the gamma-ray irradiation, the spectrum shape of Cs-137 changed due to the influence of carrier detrapping. Experimental results support that the electron-trapping center generated by fast neutrons degrades the detector performance of the CdTe detector.