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A secondary tracer approach to the derivation of galactic cosmic-ray source isotopic abundancesA formalism has been developed for deriving cosmic-ray source isotopic abundances from observed local abundances using a purely secondary nuclide as a tracer of spallation production during propagation. Although the formalism is based on the leaky-box model of cosmic-ray propagation, it is shown that source abundances derived by the tracer technique are reasonably independent of detailed propagation models. The tracer formalism also permits a quantitative evaluation of the effects of observational uncertainties on deduced source abundances. It is shown that statistical errors in the observed abundances and uncertainties in the spallation cross sections are at present the dominant sources of uncertainty. The latter error can be reduced with increased detector size or exposure time, while the former can be minimized by measurements of the relative production cross sections. As a specific example, the tracer technique is applied to the isotopes of sulfur and calcium, and the level of uncertainties which must be achieved to distinguish evolutionary differences between solar-system material and cosmic ray-source material are established.
Document ID
19790061092
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Stone, E. C.
(California Inst. of Tech. Pasadena, CA, United States)
Wiedenbeck, M. E.
(California Institute of Technology Pasadena, Calif., United States)
Date Acquired
August 9, 2013
Publication Date
July 15, 1979
Publication Information
Publication: Astrophysical Journal
Subject Category
Space Radiation
Accession Number
79A45105
Funding Number(s)
CONTRACT_GRANT: NGR-05-002-160
Distribution Limits
Public
Copyright
Other

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