Neutron capture on ¹⁴⁹Sm in lunar samples
Abstract
High precision isotopic composition measurements of Sm have been carried out for two terrestrial and seven lunar samples from three Apollo sites. The lunar samples, selected to show a wide variation in cosmic ray exposure ages, have a wide range of enrichments in ¹⁵⁰Sm/¹⁵⁴Sm (up to 0.8%) and depletions in ¹⁴⁹Sm/¹⁵⁴Sm which are due to neutron capture. The ratio of the number of neutrons captured per atom by ¹⁴⁹Sm to ¹⁵⁷Gd is 0.9 and reflects a hardened lunar neutron spectrum. This ratio is in reasonable but not exact agreement with that obtained from the theoretical lunar neutron energy spectrum of Lingenfelter, Canfield and Hampel. The average composition for terrestrial samarium is ¹⁴⁴Sm : ¹⁴⁷Sm : ¹⁴⁸Sm : ¹⁴⁹Sm : ¹⁵⁰Sm : ¹⁵²Sm : ¹⁵⁴Sm = 3.074 : 14.995 : 11.243 : 13.820 : 7.380 : 26.739 : 22.749%.
Additional Information
Discussions with F. Tera and J. Huneke were very beneficial. This work was supported by the National Science Foundation under Grant GP-28027 and in part by NASA Contract NGL-05-002-188. One of us (G.P.R.) is supported by a National Defense Education Act, Title IV, Fellowship and his wife.Additional details
- Alternative title
- Neutron capture on 149Sm in lunar samples
- Eprint ID
- 117918
- Resolver ID
- CaltechAUTHORS:20221121-280779900.3
- GP-28027
- NSF
- NGL-05-002-188
- NASA
- National Defense Science and Engineering Graduate (NDSEG) Fellowship
- Created
-
2022-11-29Created from EPrint's datestamp field
- Updated
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2022-11-29Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences
- Other Numbering System Name
- Caltech Division of Geological and Planetary Sciences
- Other Numbering System Identifier
- 2067