Abstract :
Two types of scintillation counter, employing the VX 5045 multiplier photocell and a phosphor, are described. The alpha scintillation counting equipment is a complete instrument for counting samples of low activity over an area of 10 cm2, at background rates of less than 2 counts per hour. A counting efficiency of 35% is obtained from a thin alpha-particle source with a comparative accuracy of ±1%. The scintillation gamma counter is designed as a probe unit for routine measurement of gamma-ray flux. Methods are given for the preparation of suitable phosphors. Using a thallium-activated sodium iodide phosphor, a counting efficiency of 22.5% was measured for 1.2-MeV gamma rays stable over long periods to ± 1%.
