Gross beta activity in water Cerenkov Method

Abstract

Cerenkov effect occurs when the charged particle velocity in a medium is larger than the speed of light in that medium. Cerenkov radiation is produced in water by ß-emitting radionuclides of energy greater than 265 keV. The advantages of the Cerenkov method for gross beta activity determination are simplicity of sample preparation, low cost, possibility of reusing the sample, easy discard and efficiency unaffected by chemical quenching. The aim of this study is to compare the background, efficiency, Minimum Detectable Activity (MDA) and Figure Of Merit (FOM) for the determination of ß-emitting radionuclides using two scintillation counters, Quantulus and Hidex. In order to evaluate these parameters, for both equipment, three standard solutions of gross beta activity were analyzed in triplicate. The performance of the determination of gross beta activity in water was evaluated by participating in a Proficiency Test organized by Instituto de Radioproteção e Dosimetria. The values obtained for the normalized standard deviation (D) was below 2, indicating a good precision and accuracy for both equipment.