Measurements of Ultraheavy Cosmic Rays with HEAO-3

Abstract

The HEAO-3 Heavy Nuclei Experiment has measured abundances of elements from ^(18)Ar to ^(92)U in the cosmic rays. The results of the ultraheavy elements, those with atomic numbers greater than 30, indicate that the sources of cosmic rays contain a mixture of r-process and s-process material similar to that found in the solar system. This result is at variance with previous indications that the sources are greatly enhanced with freshly synthesized r-process material. Apparent discrepancies between our results and the accepted solar-system abundances have led to a re-examination of data on photospheric abundances of Ge and Pb, resulting in suggested reductions in their values.

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