APPLICATION OF A LOW-LEVEL ANTI-COINCIDENCE GAMMA-SPECTROMETER FOR ENVIRONMENTAL-RADIOACTIVITY MEASUREMENT

Sensitive environmental radioactivity measurement using direct gamma-s pectroscopy needs to be carried out under particular low-level conditi ons as the quantity to be determined generally is very close to the na tural background. Passive shielding of the detectors in addition to el ectronic suppression of Compton background resulting from scattering o f high energy gamma-rays in the germanium detector seems to be the mos t 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 radioa ctivity in various materials are described.