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THE USE OF COMPACT CdZnTe GAMMA-RAY SPECTROMETERS IN EXTREME TEMPERATURE CONDITIONS

Artur Fattakhov, Bulat Nasyrtdinov, Ilgiz Shamsutdinov

Abstract

Gamma-ray spectrometry is one of the most important and informative methods for various geological surveys. In field geophysics on the surface or in the air, the method is used for regional geological zoning, mapping of bedrock outcrops, etc. The most promising direction of geological surveys today is research with the use of UAVs. Conducting gamma-ray spectrometry using UAVs is complicated by the need to accumulate a large number of measurements to construct the correct gamma-ray spectrum. From this point of view, the use of traditional scintillation sensors looks unattractive due to their long measurement time of a single spectrum (from 0.5 ms). An alternative is CdZnTe sensors, where the measurement of a single spectrum takes much less time (the first ms). The disadvantage of CdZnTe-sensors is their limited temperature range. Usually there is from 0?C to +30 ?C - +40?C in passports. When working with UAVs, this temperature range significantly limits the possibility of using CdZnTe sensors. An experiment was conducted in which a CdZnTe-sensor was placed in a climatic cell together with a calibrated Co60 source. The measurements were carried out in a wide temperature range. As a result of the experiment, the spectra from the Co60 source were obtained at different temperatures. This element is characterized by two energy peaks located at 1173 keV and 1332 keV. The analysis of the obtained energy spectra at different temperatures showed that the shift of the energy windows of the characteristic peaks is insignificant for passport temperature range. When the temperature drops below 0° C, the energy window begins to shift to the region of lower energies. When the temperature rises to 40° C and above, there is a sharp increase in energy in the low-energy region. The dependence of the position of the characteristic peak on the measurement temperature was constructed. The displacements in the range of 1.1-1.3 MeV are identical, which suggests that they are uniform for the entire measured energy range. The CdZnTe sensors can be used for work at extreme temperatures that go beyond the traditionally accepted temperature limits. The conducted experiment allows us to assert the possibility of using such gamma-ray spectrometers on UAVs when conducting geological surveys in northern latitudes, provided that the ambient air temperature is not lower than -20?C.

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