INVESTIGATION OF THE RADIONUCLIDE COMPOSITION OF CLAY BY SCINTILLATION γ-SPECTROMETRY

摘要

Clayey rocks comprise more than 5% of the Earth's crust. Aside from the principal components - water and aluminum and silicon oxides, they contain as impurities various minerals and organic materials, including natural radionuclides. A necessary condition for developing a deposit is measuring the concentration of these radionuclides. Investigating the spectra of natural objects imposes stringent requirements on the efficiency of a radiation detector and the energy resolution of spectrometers. For example, several tens of lines, among which lines due to the decay of ~(226)Ra, ~(232)Th, ~(40)K, and ~(235)U and their daughter radionuclides predominate, appear in the γ-ray spectra of clays in the range 100-2700 keV [1]. The situation is further complicated by the fact that the spectral composition of the background radiation detected by a detector is similar to that of the sample, and in many cases its intensity is comparable to or greater than that of the characteristic spectrum of the samples. In addition, as a result of screening, the instrumental spectrum of the background component depends on the geometric dimensions of and substances in the sample. At the present time, the most suitable detectors for such investigations are detectors consisting of ultrapure germanium with relative efficiency ε_(rel)≥ 100%. However, the high cost of such detectors limits their use. Less expensive, and therefore comparatively more accessible, scintillation detectors with the same γ-ray detection efficiency have a low energy resolution.