Cosmogenic /sup 36/Cl production rates in meteorites and the lunar surface
Activity-versus-depth profiles of cosmic-ray-produced /sup 36/Cl were measured in metal from two cores each in the St. Severin and Jilin chondrites and in lunar core 15008. Production of /sup 36/Cl in these samples range from high-energy reactions with Fe and Ni to low-energy reactions with Ca and K and possibly neutron-capture reactions with /sup 35/Cl. The cross sections used in the Reedy-Arnold model for neutron-induced reactions were adjusted to get production rates that fit the measured /sup 36/Cl activities in St. Severin metal and in the lunar soil of core 15008. The /sup 36/Cl in metal from St. Severin has a fairly flat activity-versus-depth profile, unlike most other cosmogenic nuclides in bulk samples from St. Severin, which increase in concentration with depth. In metal from Jilin, a decrease in /sup 36/Cl was observed near its center. The length of Jilin's most recent cosmic-ray exposure was /approximately/0.5 My. Lunar core 15008 has an excess in /sup 36/Cl of about 4 dpm/kg near its surface that was produced by solar-proton-induced reactions. The calculated production rates are consistent with these measured trends in 15008. 39 refs., 4 figs., 3 tabs.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36; W-31109-ENG-38
- OSTI ID:
- 7137860
- Report Number(s):
- LA-UR-88-1878; CONF-880391-2; ON: DE88014452
- Resource Relation:
- Conference: GEOTIMES: 19th lunar and planetary science conference, Houston, TX, USA, 14 Mar 1988; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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GENERAL PHYSICS
CHLORINE 36
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LUNAR MATERIALS
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BETA-MINUS DECAY RADIOISOTOPES
CHLORINE ISOTOPES
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640101* - Astrophysics & Cosmology- Cosmic Radiation