Measurements of short-lived cosmogenic nuclides in rain samples.

Extremely low activity levels of cosmic ray induced nuclides have been measured in freshly precipitated rainwater by quick chemical separation coupled with ultra low background gamma-spectrometry. The nuclides detected were ³⁸S ( T _1/2 = 2.83 h)-³⁸Cl (37.2 m), ³⁹Cl (55.6 m), ²⁴Na (14.96 h), ²⁸Mg (20.9 h), ⁷Be (53.3 d) and ²²Na (2.602 y). The number of atoms in rain water were evaluated to be ranging from 400-1900 l^-1 for ³⁹Cl ( n = 6, mean: 1200), 30-1500 l^-1 for ²⁴Na ( n = 16, mean: 520), 80-600 l^-1 for ²⁸Mg ( n = 13, mean: 260), 1 ^. 10⁶-4 ^. 10⁷ l^-1 for 7Be ( n = 16, mean: 7 ^. 10⁶) and 2 ^. 10³-1 ^. 10⁵ l^-1 for ²²Na ( n = 9, mean: 2 ^. 10⁴). Measurements of activity levels and activity ratios of short-lived cosmic-ray induced short-lived nuclides will open new method to understand atmospheric processes occurred at the altitude of rain cloud. [ABSTRACT FROM AUTHOR]