A development for determining the activity of radionuclides in the environmental sample by HPGe γ-spectroscopy using only one absolute efficiency value and an intrinsic efficiency curve

摘要

In this paper, we presented a development for determining the radio-activities in an environmental sample when solely knowing the absolute (full-energy peak) efficiency value at the energy of 1460.83keV corresponding to the characteristic gamma-ray of K-40 by using a separate reference and an intrinsic (relative) efficiency function. A Geant4 code and labSOCS were used to study the influences of chemical composition and density on absolute efficiency and relative self-absorption correction factor at 1460.83keV. The prerequisite for using this method is the presence of a multi-gamma-ray emitter in the sample, with an activity allowing to measure the count rates with a low statistics uncertainty (few percents). Two standard samples were used to validate the development. In addition, five soil samples collected in Laos were used to evaluate the practical application of the development. Gamma-rays from Th-228 or Ra-226 decay series were chosen to construct the intrinsic efficiency functions. The results obtained in this work were in fair agreement with reference data.