Development of a combination detector system for simultaneous measurement of α and β/γ radioactivity

Abstract

Accurate estimation of radioactivity content of various samples and effluents is essential in all stages of operation at a nuclear facility. Generally, two separate systems are used for estimation of α and gross β activity. A single counting setup with a detector probe consisting of a combination of ZnS (Ag) and plastic scintillator detectors can be applied for this purpose. This paper describes design, development, and characterization of a combination detector system for simultaneous assessment of α and β/γ radioactivity content of an electrodeposited or planchetted sample or that of a filter paper. Pulse height discrimination technique has been utilized to distinguish between α and β radiations. The β activity counts had been observed to contribute <0.7% in α activity. Counts from α activity are added up in β channel counts, and it was observed that for 239Pu source, it is about 2.5 times. Efficiency of the system for β sources was found to have varied from about 14% (137Cs) to 23% (90Sr/90Y). The efficiency for 238Pu α source was found to be 13.4%.

Keywords

• Combination detector
• pulse height discrimination
• thin plastic scintillator
• ZnS (Ag)