Fast Neutron Damage of a Pixelated CdZnTe Gamma Ray Spectrometer

This study describes the damage to a pixelated 1 cm times 1 cm times 1 cm CdZnTe detector caused by fast neutrons in the energy range 1-7 MeV. Measurements of electron mutau product were performed before and after irradiation and also following thermal annealing. Spectroscopic information was acquired with a ¹³³Ba gamma source. Before neutron irradiation, sharp peaks were observed for the ¹³³Ba lines, with combined pixel energy resolution for the 356 keV line of 2.1% FWHM. After irradiation, clear deterioration of the spectral response is observed, with combined energy resolution of the 356 keV line of about 6% FWHM. After thermal annealing, the spectral response shows significant recovery, with combined energy resolution of 2.3% FWHM. We successfully simulate these results with a theoretical model. It is concluded that the fast neutrons cause displacement damage in the lattice of the bulk CdZnTe material.