Study on the Energy Spectrum Response of a CdZnTe Detector

Abstract

In order to study the energy spectrum response of a CdZnTe detector, we firstly measured the temperature dependence and the bias dependence of the main characteristic parameters for both a quasi-hemispherical detector and a CAPture™ plus detector. Secondly, we designed a low-noise readout circuit for the CdZnTe detector and measured the noise. Finally, we evaluated the energy spectrum response of the detector to different radioactive sources at different temperatures by connecting the detector to the readout circuit. The research showed that both detectors had low leakage current and junction capacitance, as well as good stability in temperature and bias; the quasi-hemispheric detector had a smaller leakage current and junction capacitance compared to the CAPture™ plus detector; under zero input capacitor, the noise of the readout circuit was 612e, with the noise slope being 5.44e/pF; at room temperature(20 °C), the energy resolutions of the detector reached 3.84% and 1.36% for X-rays from ²⁴¹Am (59.5 keV) and gamma-rays from ¹³⁷Cs (662 keV), respectively; the signal-noise ratio of the output signal reached 31:1 with the rise time being 90 ns; at low temperature, the energy resolution reached 3.41% for the X-rays from ²⁴¹Am (59.5 keV); the detector achieved an excellent spectrum response and was able to distinguish clearly the energy peaks of ¹⁵²Eu and ²²⁶Ra.