An open multiple GM-counter for the measurement of low-energy beta samples

For the measurement of low-energy beta activity, an open, multiple gas flow GM-counter has been developed. The counter is espesially developed for the measurement of low-energy 63Ni samples electrolyzed on thin steel sheets. Four samples may be simultaneously measured in four counting elements integrated into the same mechnanical unit. A common guard counter reduces the background noise by the use of anticoincidence techniques. Mounted into a 100 mm thick lead screen, the GM-counter operates in a background radiation of appr. 0.2 cpm. Preliminary measurements on electrolyzed 63Ni samples, show a counting efficiency of appr. 40%