Determination of Radioactive Content of Rocks by Means of Geiger-Müller Counters

Abstract

During a survey of the Velence Mountains in Hungary the authors developed a direct approximating method for use in determining the radioactive content of rocks by means of a Geiger-Mueller counter. The calibration method used is outlined and the calibration obtained can be expressed by the following approximate numerical formula: c = 2.4 . 10/sup -5/ J/LD, where c is the concentration in g-Th-equivalents/g of rock; J, the counting rate (in min); L the length; and D the diameter (in cm) of the brass cathode of the counter tube. Similarly the concentration in g-U-equivalents/g of rock can be expressed by the approximate numerical formula: c = 1.4 . 10/sup -5/ J/LD. The use of the following roughly approximating simple rule may be suggested for uranium explorers when extended territories must be surveyed within a short time: if a G-M counter of any commercial dimensions, shielded by 2 mm of lead, is placed against the rock wall and the observed counting rate (minus cosmic radiation) is x times the rate of cosmic radiation for the same counter, then the average U concentration in the rock is x times 25 g U/metric ton (1,000 kg) of rock.