The results of a study of some ways to improve spectroscopy characteristics of the CdZnTe quasi-hemispherical detectors when working in high gamma radiation fluxes are presented. It was shown that the use of IR illumination with a wavelength of 1050 nm or 1200 nm or at slight warm-up of the detector to +30°C … +40°C can significantly improve spectroscopy performance of the CdZnTe detectors of size 3.5 mm × 3.5 mm × 1.75 mm when operating in a tested gamma-radiation field with a dose rate up to 590 mGy/h.

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The work presents analysis of the correlation existing between the spectrometric performance of commercially produced hemispherical detectors of volume 500 mm 3 and the quality of starting CdZnTe material. More then 100 detectors made from CdZnTe crystals grown by eV Products, Saint-Gobain and Yinnel Tech. were studied. For the incoming inspection of the material an infrared (IR) transmission microscope was used. The presence of structural defects such as grain boundaries, twins, inclusions and cavities was checked and their shapes, sizes and spatial distributions were examined; the values of electron mobility-lifetime product (µτ) e were measured. The hemispherical detectors were made by a technology elaborated at the RITEC. Spectrometric performance of the detectors was verified by measuring the energy resolution and the peak-to-Compton ratio at the 662 keV line. It was found that all tested detectors had numerous structure defects, whose shapes, sizes, numbers and spatial distributions varied from sample to sample. Were found that hemispherical detectors made from samples containing inclusions of irregular shape had a poor spectrometric performance, while the detectors from samples containing large inclusions (>50 µm) of regular shape (triangular, hexagonal) as a rule performed well. It was also found that a highly non-uniform spatial distribution of structural defects usually leads to a poor spectrometric performance.

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