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 urani um, thorium and potassium in rock and soil samples is described. The p rocedure described exploits the fact that a large proportion of gamma quanta produced in the Th and U decay series have energies of less tha n 1 MeV. The instrumental parameters such as sensitivity and detection limits for the low-energy region have been studied. The measuring con ditions were optimized by suitably minimizing the background and by in creasing the overall sensitivity with the help of proper geometry of m easurement and sample parameters. High sensitivity and low detection l imits for U and Th can be achieved using low-energy gamma ray spectrom etry. The method provides a rapid analysis with a counting time of the order of a few minutes for each sample.