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

None

竹安 正則 ; 飯田 孝夫*; 辻本 忠*; 山崎 敬三*

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

雨水中のPbおよびBi の濃度と濃度比を低BGゲルマ検出器を用いた線スペクトロメトリーにより測定した。また、測定結果と、降水による大気中ラドン壊変生成物の除去モデルによる計算結果を比較した。一雨における雨水中のPbおよびBiの個別濃度は、降水強度に依存せず一定の場合と、降水強度とべき関数の関係にある場合が観測された。また、PbとBiの濃度比は降水強度と弱い逆相関関係があり、この測定結果は、モデルによる計算結果と比較的よく一致した。

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.