DETERMINATION OF URANIUM, THORIUM AND POTASSIUM CONTENTS IN ROCK AND SOIL SAMPLES USING LOW-ENERGY GAMMA-RAY SPECTROMETRY

A low-energy gamma ray spectrometric set-up for determination of uranium, thorium and potassium in rock and soil samples is described. The procedure described exploits the fact that a large proportion of gamma quanta produced in the Th and U decay series have energies of less than 1 MeV. The instrumental parameters such as sensitivity and detection limits for the low-energy region have been studied. The measuring conditions were optimized by suitably minimizing the background and by increasing the overall sensitivity with the help of proper geometry of measurement and sample parameters. High sensitivity and low detection limits for U and Th can be achieved using low-energy gamma ray spectrometry. The method provides a rapid analysis with a counting time of the order of a few minutes for each sample.