Gamma Ray Spectrometry of the Natural Radioactivity in the Airborne Dust

Abstract

By means of γ ray spectrometry, a qualitative variation in the diurnal variation of the natural radioactivity in the airborne dust was observed. The radioactive decay rate of the total natural radioactivity in the airborne dust collected during the day was higher than that collected during the night. It was found that the ratio of ²¹²Pb (Th B) γ activity to the total γ activity was higher in the night and lower in the day, on the other hand, the ratios of ²¹⁴Pb (Ra B) and ²¹⁴Bi (Ra C) were a little higher in the day than in the night. From the observations, it was concluded that the quantitative diurnal variation of the natural radioactivity in the airborne dust was associated also with the qualitative variation derived from the variation in the abundance ratio of nuclide.