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The isotopic composition of iron-group galactic cosmic raysResults from studies of the isotopic composition of iron group elements in the galactic cosmic radiation are reviewed, emphasizing recently reported measurements from the ISEE-3 spacecraft. The observed isotope distributions for the elements Ti through Mn are in good agreement with those expected for a propagated solar-like source composition, with the possible exception of an enhanced abundance of Ti-50. It is found that a significant fraction of the radioactive secondary nuclide Mn-54 has decayed, indicating a confinement time of iron group cosmic rays in the galaxy of at least 2 Myr. The source ratio Fe-54/Fe-56 is found to be consistent with the solar value, but the ratio Ni-60/Ni-58 is greater than solar by a factor of 2.8+/-1.0. The measured abundance of Co-59 is significantly greater than the calculated secondary contribution, suggesting that this nuclide has been produced in the source regions by the electron capture decay of Ni-59 and implying a time delay between nucleosynthesis and acceleration approximately greater than 10(exp 5) yr.
Document ID
19950028909
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Wiedenbeck, M. E.
(Univ. of Chicago, Chicago, IL US, United States)
Leske, R. A.
(Univ. of Chicago, Chicago, IL US, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1995
Publication Information
Publication: Advances in Space Research
Volume: 15
Issue: 1
ISSN: 0273-1177
Subject Category
Space Radiation
Accession Number
95A60508
Funding Number(s)
CONTRACT_GRANT: NAGW-1982
CONTRACT_GRANT: NAG5-308
CONTRACT_GRANT: NGT-14-020-802
Distribution Limits
Public
Copyright
Other

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