1988 年 23 巻 3 号 p. 209-215
It is important to know the over-all counting efficiency of measuring apparatus. In this work, the counting efficiency of ZnS (Ag) scintillation counter was discussed with regard for counting radon daughter products sampled on a filter paper. The results are as follows; (1) It is unsuitable to use a counting efficiency for sources such as U3O8 or Am-241 instead of using radon short-lived daughter products. (2) The counting efficiency of ZnS (Ag) scintillation counter is decided from results obtained by counting radon short-lived daughter products on a membrane filter with gridded ionization chamber. (3) The over-all counting efficiency is obtained from product of the counting efficiency of detector, the emerging efficiency and the sampling efficiency.