title: Analysis of krypton-85 and krypton-81 in a few liters of air.
abstract: Long-lived radioactive krypton isotopes, (81)Kr (t1/2 = 229,000 year) and (85)Kr (t1/2 = 10.76 year), are ideal tracers. (81)Kr is cosmogenic and can be used for dating groundwater beyond the (14)C age. (85)Kr 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 × 10(5). This work presents a system developed to analyze (81)Kr and (85)Kr 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. (85)Kr/Kr and (81)Kr/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 (81)Kr and (85)Kr in environmental samples including air, groundwater, and ices.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China , Hefei 230026, Anhui Province, People's Republic of China.
authors.forename: Le-Yi
authors.initials: LY
authors.lastname: Tu
authors.forename: Guo-Min
authors.initials: GM
authors.lastname: Yang
authors.forename: Cun-Feng
authors.initials: CF
authors.lastname: Cheng
authors.forename: Gu-Liang
authors.initials: GL
authors.lastname: Liu
authors.forename: Xiang-Yang
authors.initials: XY
authors.lastname: Zhang
authors.forename: Shui-Ming
authors.initials: SM
authors.lastname: Hu