Basic parameters of gamma spectrometry system based on CZT crystal and its use in school didactic experiments

The paper deals with the basic characteristics of the gamma spectrometric system designed for school experiments, with a detector based on CZT (cadmium-zinc-telluride) semiconductor crystal. Spectrometer RadAngel for Schools^TM (RA4STM) from manufacturer Kromek Group plc. is equipped with a 5 · 5 · 5 mm CZT detector, compact design (90 mm · 55 mm · 25 mm), small weight (135 g), integrated electronics with USB connection to PC and basic spectrometric software. The manufacturer declares an energy resolution of <3.5% FWHM for 662 keV and energy range of 40 - 1500 keV with spectrum size of 4096 channels. Due to the absence of detector efficiency data, we focused on the determination of the peak efficiency (full energy peak efficiency) for the declared energy range and determination of energy resolution (FWHM) as a function of peak energy. The results show that RA4S exceeds manufacturer's declared values in several parameters. In the paper we present the sample spectra measured using the KCl sample as well as the spectrum of calibration standard in the Marinelli beaker geometry used for energy, FWHM and efficiency calibration. Peak efficiency values are relatively low, which is agreement with expectations due to the small effective volume of the detector. Finally, there are several suggestions for school experiments using the features of the device described. (author)