Analog rise-time discriminator for CdZnTe detector

Due to variable time for charge collection, energy resolution of nuclear detectors declines, especially compound semiconductor detectors like cadmium zinc telluride (CdZnTe) detector. To solve this problem, an analog rise-time discriminator based on charge comparison principle is designed. The reference charge signal after attenuation is compared with the deconvoluted and delayed current signal. It is found that the amplitude of delayed current signal is higher than that of the reference charge signal when rise time of the input signal is shorter than the discrimination time, thus generating gating signal and triggering DMCA (digital multi-channel analyzer) to receive the total integral charge signal. When rise time of the input signal is longer than discrimination time, DMCA remains inactivated and the corresponding total integral charge signal is abandoned. Test results show that combination of the designed rise-time discriminator and DMCA can reduce hole tailing of CdZnTe detector significantly. Energy resolution of the system is 0.98%@662 keV, and it is still excellent under high counting rates.