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在用γ谱技术测定环境样品中的~(226)Ra活度工作中,不少分析工作者习以为常地认为:样品在制备成待测样品后密闭封存四到五个~(222)Rn的半衰期(15～20d)后,即可用测定其子体~(214)Pb的活度来表征~(226)Ra的活度。但通过严密的公式推导从理论上揭示,对于诸如水样品等一些在制样过程中发生严重~(226)Ra-~(222)Rn平衡破坏的样品,15～20天的平衡时间是远不
In the determination of the activity of ~ (226) Ra in environmental samples by γ-spectrometry, many analysts consider it common: the half-life of four to five (222) Rn is sealed tightly after preparation of the sample to be tested (15-20d), the activity of ~ (226) Ra can be characterized by measuring the activity of ~ (214) Pb in its daughter. However, the tight formula deduction theoretically reveals that the equilibrium time of 15-20 days is far less than that of some samples such as water samples that have undergone severe equilibrium destruction of 226- (222) Rn during sample preparation