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 × 10 8 -1.8 × 10 11 n/cm 2 . The effect of γ-ray heavy irradiation toward the detector was also investigated for the comparison. Americium-241 and 137 Cs γ-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 elections and holes. Peak shift toward lower energies was observed in the 241 Am γ-ray spectrum after fast neutron irradiation. Electron μτ product showed large decrease with increasing the neutron fluence, while the one for holes remained unchanged. For the γ-ray irradiation, the spectrum shape of 137 Cs 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.