Variation of cosmogenic Kr and Xe in a core from Estherville mesosiderite: direct evidence that the lunar $sup 131$Xe anomaly is a depth effect
Kr and Xe were measured by a stepwise heating technique in three samples of a drill core in the Minnesota'' fragment of the Estherville mesosiderite. The cosmogenic /sup 78/Kr//sup 78/Kr decreased from the top'' sample to the bottom'' sample ( top'' = 0.163 plus or minus 0.005, bottom'' = 0.151 plus or minus 0.005) while the cosmogenic /sup 131/Xe//sup 126/X e ratio increased ( top'' = 5.58 plus or minus 0.35, ''bottom'' = 6.92 plus or minus 0.17). Cosmic-ray track studies have shown that the top'' sample was indeed closer to the pre-atmospheric surface than the bottom'' sample by ~10 cm. This is the first direct evidence, in a sample of known geometry, that the cosmogenic /sup 131/Xe//supl26/Xe ratio increases as a function of depth, and as such, confirms the hypothesis that the lunar /sup 131/Xe anomaly is a bona fide depth effect due to resonance neutron capture in /sup 130/Ba. (auth)
- Research Organization:
- Univ. of California, Berkeley
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-013337
- OSTI ID:
- 4374616
- Journal Information:
- Earth Planet. Sci. Lett., v. 20, no. 2, pp. 286-294, Journal Name: Earth Planet. Sci. Lett., v. 20, no. 2, pp. 286-294; ISSN EPSLA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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