A Miniaturized Gamma-ray Spectrometer based on CdZnTe Semiconductor and BGO Scintillator

Abstract

A miniaturized gamma-ray spectrometer, which is designed for the applications of gamma-ray detection, is described in this paper. It can be used in radiation protection, environment exploration and physics research. The detector consists of a CdZnTe (CZT) semiconductor and a BGO scintillator. With the structure of a CZT module assembled in the cavity of a cup-shaped BGO, the detector has the functions of rapid detection just using BGO, angular sensitivity and Compton suppression using CZT with BGO as a collimator and anti-coincidence detector. For the developed prototype spectrometer, the readout electronics was designed to sample the signal from the detector and to process the data on FPGA. It is well-coordinated with the detector. For Compton suppression, the energy threshold of BGO signal is set to 50keV and anti-coincidence time window is set to ±2μs. The design of the detector is evaluated by simulation and the performance of the spectrometer is tested. Simulated results are in agreement with test results. The energy resolution of 1.8% at 662keV has been achieved and Compton suppression factor has reached 30% for gamma-ray energy spectrum measurement with Compton suppression, which is helpful for identification of full energy peaks. The angular sensitivity of forward directions is higher than the side which is meaningful for search and preliminary location measurement of radioactive materials.