Spectrum Construction Methods Improving Gamma-Ray Detection Efficiency for Pixelated CZT Detectors

Two spectrum construction methods are introduced, which can mitigate the effect of Compton scattering and charge sharing on the photopeak detection efficiency of gamma rays for pixelated cadmium zinc telluride (CdZnTe) detectors. Energy sums and energy combination sums are used for spectrum construction, respectively. Monte Carlo simulations have been done to evaluate their effectiveness. A model of a $22\times 22\times15$ mm pixelated CZT detector was created with an $11\times11$ -pixel array in the simulations. It is confirmed that the spectrum constructed by energy combination sums functions well under high-intensity and high-energy gamma-ray radiation, while the spectrum from energy sums is functional only under low-intensity radiation. What is more, it is found that the detection efficiency improvement brought by the two methods will be reduced when the energy resolution of the detector gets worse. The best detection efficiency for 662-keV gamma rays achieved by the spectrum consisting of energy combination sums is 14.4%, much higher than the one from the sum of each pixel's spectrum (SEPS), which is 5.9%.