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Published November 15, 1989 | Published
Journal Article Open

Abundances of ultraheavy elements in the cosmic radiation: results from HEAO 3


We report here an analysis that, for the first time, systematically normalizes the data from the HEAO 3 Heavy Nuclei Experiment on .the cosmic-ray abundances of all the elements heavier than germanium to that of .iron. In the range of atomic number Z, 33 ≤Z ≤60, the analysis yields abundances of odd-even element pairs. These abundances are consistent with a cosmic-ray source having a composition similar to that of the solar system, but subject to source fractionation correlated with the first ionization potential (FIP) of each element. For Z > 60, the analysis yields abundances of element groups. For these heaviest nuclei, we find an enhancement of the abundance of the platinum group, elements with 74 ≤ Z ≤ 80, relative to that in a propagated solar system source, and a corresponding increase in the abundance of the largely secondary elements in the range 62 ≤ Z ≤ 73. These abundances suggest that there is an enhancement of the r-process contribution to the source nuclei in the Z > 60 charge region. Over the entire region of charge, standard leaky box models of propagation satisfactorily model secondary production.

Additional Information

© 1989 American Astronomical Society. Received 1989 February 21; accepted 1989 May 12. This research was supported in part by NASA under grants NAG 8-498, 500, and 502; and NGR 0-02-160, 24-00-50, and 26-008-001. Brownlee Gauld's assistance in computer programming was exceptional.

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Published - 1989ApJ___346__997B.pdf


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