Measurements of Concentrations and its Ratio of Radon Decay Products in Rainwater by Gamma-Ray Spectrometry with a Low Background Germanium Detector

Takeyasu, Masanori; Iida, Takao*; Tsujimoto, Tadashi*; Yamasaki, Keizo*

Proceedings of 6th International Conference on High Levels of Natural Radiation and Radon Areas, Program & Abstracts, (P-22), 85 Pages, 2004/00

The concentrations and its ratio of Pb-214 and Bi-214 in rainwater were measured by -ray spectrometry with a low background Ge detector, and the results were compared with the scavenging model of radon decay products from the atmosphere by precipitation. The each concentration of Pb-214 and Bi-214 in rainwater was constant and independent on precipitation rate for some precipitation events, and expressed with a power function of precipitation rate for the other events. The activity ratio of Bi-214 to Pb-214 was observed weak inverse correlated with precipitation rate. The measured ratio agreed fairly well with calculated one by the model.