High resolution gamma-spectroscopy of environmental samples

Abstract

In this study, a comparison has been made between the available commercial software package Genie 2000 developed by Canberra and Virtual Gamma Spectroscopy Laboratory (VGSL) developed by the Radionuclide Development Unit of the International Data Centre of the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) to provide quality assessment of the data delivered by eighty (80) international monitoring stations distributed around the world to monitor nuclide emissions after an illegal nuclear weapon test, either in the atmosphere, under water or underground. The lessons learned from the Proficiency Test Exercises (PTEs) will be applied to NORM nuclide analyses of environmental samples. Results provided are based on three (3) IAEA reference materials: stream sediments, milk powder, and soil. These samples contain decay products of uranium and thorium, which produce multiple gamma-rays, and thus a High Purity Germanium detector (HPGe) will be used. The study has been conducted in the South African CTBTO laboratory (ZAL14) situated at the South African Nuclear Energy Corporation SOC Ltd. The laboratory is equipped with two ultra-low background gamma-spectrometry systems accredited according to world-class standards. The CTBTO PTEs spectra and IAEA certified samples have been analyzed looking at a variety of parameter settings including sum-coincidence and matrix-dependent self-absorption using both software mentioned. Optimization of various parameters has been done by gamma-ray spectra used in the CTBTO proficiency tests over the past decade.