New Measurements of the Isotopic Composition of Galactic Cosmic Ray Elements Cu, Zn, Ga, Ge, As and Se

ORAL

Abstract

The Cosmic Ray Isotope Spectrometer (CRIS) instrument on the NASA Advanced Composition Explorer (ACE) satellite was launched in August, 1997, and has collected data over this $\sim$22 year period of time. The large geometrical factor of the instrument, combined with the very long exposure time, has enabled us to measure the cosmic ray isotopic abundances of $_{31}$Ga, $_{32}$Ge, $_{33}$As, and $_{34}$Se for the first time, and to greatly improve earlier published measurements for $_{29}$Cu and $_{30}$Zn. We have collected a total of more than 1100 nuclei with Z=30 or greater, with energies in the range of $\sim$150 to 600 MeV/nucleon. In this paper we report preliminary isotopic cosmic-ray composition measurements and compare the observed isotopic fractions with those in the solar system.

*This research is supported by NASA

–

Authors

  • W.R. Binns

    • Washington University, St. Louis

  • E.R. Christian

    • NASA/Goddard Space Flight Center, Greenbelt, MD

  • A.C. Cummings

    • California Institute of Technology, Pasadena, CA

  • G.A. de Nolfo

    • NASA/Goddard Space Flight Center, Greenbelt, MD

  • M.H. Israel

    • Washington University, St. Louis

  • R.A. Leske

    • California Institute of Technology, Pasadena, CA

  • R.A. Mewaldt

    • California Institute of Technology, Pasadena, CA

  • E.C. Stone

    • California Institute of Technology, Pasadena, CA

  • T.T. von Rosenvinge

    • NASA/Goddard Space Flight Center, Greenbelt, MD

  • M.E. Wiedenbeck

    • Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA