Conditions for obtaining comparable data in field gamma spectrometry

The effects of correct instrument performance, the method of calibration and the methodology of field measurements and calculations on the comparability of results of field gamma spectrometry are discussed. All field spectrometers used by the Uranium Industry are calibrated by the Industry's own calibration base. The calibration of the spectrometer provided equations for the calculation of K, U and Th concentrations. The importance is pointed out of using them in a nontruncated form. In evaluating total radioactivity obtained with different types of spectrometers, the calculated values should be unified to the conditions of equal detection efficiency and discrimination level. The proven values of the uranium equivalents, Esub(K)=2.79 and Esub(Th)=0.49, are recommended for the calculation of total radioactivity from detected concentrations for discrimination level 0.4 MeV and a common detector size. Data normalizing should create preconditions for standard data filing and their use for both survey purposes and the study of the distribution of radioactive elements in rocks and geological areas. (B.S.)