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为了研究降雨对空气中短寿命氡子体的清洗机制,设计了分别模拟大气降雨的水汽凝结过程和雨粒下降过程的两个实验装置,并进行了多次实验,实验水样采用低本底γ能谱仪进行测量。实验结果表明:凝结水的短寿命放射性计数与本底相近,说明水汽凝结不能俘获短寿命氡子体。某一次自来水冲刷空气后获得了高出本底30.9%的初始γ计数,其半衰期为35.7 min,纯净水冲刷空气后获得了高出本底19.6%的初始γ计数,这些计数主要是由氡子体214Pb和214Bi引起的。可见,无论是自来水还是纯净水,它们冲刷空气后都能俘获短寿命氡子体,且半衰期和放射性核素种类均与雨水相似。这一实验结果充分说明:大气降雨的短寿命放射性不是在水汽凝结阶段而是在降落阶段对空气的冲刷获得的,是在降落过程中俘获了空气中的短寿命氡子体214Pb和214Bi而引起的。本次实验结果为降雨对空气中短寿命氡子体的冲刷清洗机制提供了最有力的证据。
In order to study the mechanism of rainfall on short-lived radon progeny in air, two experimental devices were designed to simulate the process of water vapor condensation and the process of rain particles descent, respectively. Several experimental experiments were carried out. The experimental samples with low background γ Spectrometer to measure. The experimental results show that the short-lived radioactive counts of condensed water are similar to the background, indicating that water vapor condensation can not capture short-lived radon progeny. One initial tap water scrubbed air yielded an initial gamma count of 30.9% above background, with a half-life of 35.7 min, an initial gamma count of 19.6% above the background after purging the air with pure water, and these counts were predominantly radon Body 214Pb and 214Bi caused. It can be seen that either tap water or pure water can capture short-lived radon progeny after flushing air, and the half-life and radionuclide types are similar to rainwater. This experimental result fully shows that the short-lived radioactivity of atmospheric rainfall was obtained not only during the water vapor condensation phase but also during the landing phase by capturing air short-lived radon progeny 214Pb and 214Bi during the landing of. The results of this experiment provide the most powerful evidence for rainfall erosion and cleaning mechanism of short-lived radon progeny in the air.