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摘要
Long-lived radioactive krypton isotopes, Kr-81 (t(1/2) = 229 000 year) and Kr-85 (t(1/2) = 10.76 year), are ideal tracers. Kr-81 is cosmogenic and can be used for dating groundwater beyond the C-14 age. Kr-85 is a fission product and can be applied in atmospheric studies, nuclear safety inspections, and dating young groundwater. It has long been a challenge to analyze radio-krypton in small samples, in which the total number of such isotopes can be as low as 1 x 10(5). This work presents a system developed to analyze Kr-81 and Kr-85 from a few liters of air samples. A separation system based on cryogenic distillation and gas chromatographic separation is used to extract krypton gas with an efficiency of over 90% from air samples of 1-50 L. Kr-85/Kr and Kr-81/Kr ratios in krypton gases are determined from single-atom counting using a laser-based atom trap. In order to test the performance of the system, we have analyzed various samples collected from ambient air and extracted from groundwater, with a minimum size of 1 L. The system can be applied to analyze Kr-81 and Kr-85 in environmental samples including air, groundwater, and ices.
- 出版日期2014-4-15
- 单位中国科学技术大学; 中国地质科学院; 中国地质科学院水文地质环境地质研究所
