Application of a low-level anti-coincidence gamma-spectrometer for environmental radioactivity measurement

Sensitive environmental radioactivity measurement using direct γ-spectroscopy needs to be carried out under particular low-level conditions as the quantity to be determined generally is very close to the natural background. Passive shielding of the detectors in addition to electronic suppression of Compton background resulting from scattering of high energy γ-rays in the gemanium detector seems to be the most promising approach to obtain statistically well defined peaks within reasonable measurement time. Results obtained with a heavily shielded anti-coincidence spectrometer installed at the Research Center Julich, ideally suited for the measurement of low-level environmental radioactivity in various materials are described.