Efficiency calibration and measurement of self-absorption correction for environmental gamma-spectroscopy of soil samples using Marinelli beaker

Abstract

A nonlinear function was applied in combination with the method of mixing activity calibration for fitting the experimental peak efficiency of HPGe spectrometers in the 50-2614 keV energy range. The preparation of Marinelli beaker standards of mixed gamma- and RG-Set at secular equilibrium with its daughter radionucliedes was studied. Self-absorption was measured for the activity calculation of the gamma-ray lines for daughters of 238U series, 232Th series, as well as 137Cs and 40K in soil samples. Self-absorption in the sample depends on a number of factors including sample composition, density, sample size and gamma-ray energy. Seven Marinelli beaker standards were prepared in different degrees of compaction with bulk density (ρ) of 1.000 to 1.600 g·cm-3. The detection efficiency versus density was obtained and the equation of self-absorption correction factors was calculated for soil samples. © 2006 Akadémiai Kiadó.