Simulation of characteristics of Cd(Zn)Te-detectors for radionuclide identification devices

Room-temperature nuclear radiation detectors based on wide band-gap semiconductors have good application prospects in the compact systems intended for detecting low-level radiation and identifying radionuclides. We investigated the algorithm based on the linear regression for reconstructing the spectra of beta- gamma-radiation from mixed sources located in the sufficiently thin surface layer of soil obtained by CdZnTe detector. This algorithm gave a possibility for in-situ identification of radionuclides, which were contained in the mixture composition, and determination of the ratio of their activities and under certain conditions the values of their activities without preliminary selection and preparation of samples. The response of CdZnTe detector to radiation from ¹³⁷Cs, ⁹⁰Sr, ⁴⁰K, ¹³¹I and ⁶⁰Co was obtained via Monte-Carlo simulation using GEANT4 package. It allowed us to create a database of spectral signatures for the investigated detector and to use them as input data for the linear regression model. The analysis of change in the response functions of the CdZnTe detector with the increasing thickness of the Al β-filter and the surface layer of soil, which covers the source, was conducted.