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Search for Cm-248 in the early solar systemPossible evidence for the presence of Cm-248 in the early solar system was reported from fission gas studies (Rao and Gopalan, 1973) and recently from studies of very high nuclear track densities (not less than 5 x 10 exp 8/sq cm) in the merrillite of the H4 chondrite Forest Vale (F.V.) (Pellas et al., 1987). We report here an analysis of the isotopic abundances of xenon in F.V. phosphates and results of track studies in phosphate/pyroxene contacts. The fission xenon isotopic signature clearly identifies Pu-244 as the extinct progenitor. We calculate an upper limit Cm-248/Pu-244 to be less than 0.0015 at the beginning of Xe retention in F.V. phosphates. This corresponds to an upper limit of the ratio Cm-248/U-235 of not greater than 5 x 10 exp -5 further constraining the evidence for any late addition of freshly synthesized actinide elements just prior to solar system formation. The fission track density observed after annealing the phosphates at 290C (1 hr, which essentially erases spallation recoil tracks) is also in agreement with the Pu-244 abundance inferred from fission Xe. The spallation recoil tracks produced during the 76 Ma cosmic-ray exposure account for the very high track density in merrillites.
Document ID
19930029965
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Lavielle, B.
(CEA Centre d'Etudes Nucleaires de Bordeaux-Gradignan, Gradignan, France)
Marti, K.
(California Univ. La Jolla, United States)
Pellas, P.
(NASA Lyndon B. Johnson Space Center Houston, TX, United States)
Perron, C.
(Museum National d'Histoire Naturelle Paris, France)
Date Acquired
August 15, 2013
Publication Date
September 1, 1992
Publication Information
Publication: Meteoritics
Volume: 27
Issue: 4
ISSN: 0026-1114
Subject Category
Lunar And Planetary Exploration
Accession Number
93A13962
Funding Number(s)
CONTRACT_GRANT: NAG9-41
Distribution Limits
Public
Copyright
Other

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