Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published January 15, 1988 | Published
Journal Article Open

Cosmic-ray energy spectra between 10 and several hundred GeV per atomic mass unit for elements from _(18)Ar to _(28)Ni - Results from HEAO 3

Abstract

The Heavy Nuclei Experiment on HEAO 3 included ionization chambers and a Cherenkov detector. For nuclei that arrive at locations and from directions with high geomagnetic cutoff ( > 8 GV) the Cherenkov signal determines the atomic number, Z, while the relativistic rise in ionization provides a measure of the energy. For the secondary cosmic-ray elements, _(19)K, _(21)Sc, _(22)Ti, and _(23)V, the abundances relative to _(26)Fe fall as power laws in energy; combining our results from 10 to ~200 GeV per amu with data between 1 and 25 GeV per amu from another instrument on the same spacecraft gives exponents -0.31 ± 0.01, -0.25 ± 0.02, -0.28 ± 0.01, and -0.23 ± 0.02, respectively. For _(28)Ni, which like _(26)Fe is a primary element, the abundance relative to _(26)Fe is essentially independent of energy over the interval from ~10-500 GeV per amu. The elements _(18)Ar and _(20)Ca, which at a few GeV per amu are mixtures of primary and secondary components, display abundances relative to _(26)Fe which fall with increasing energy up to ~100 GeV per amu and then level off at higher energies; from the energy dependence of these abundance ratios we infer Ar/Fe and Ca/Fe ratios in the source of 2.6 ± 0.7% and 8.8 ± 0.7%, respectively.

Additional Information

© 1988 The American Astronomical Society. Received 1987 May 8; accepted 1987 July 13. This work was supported in part by NASA grants NAG 8-498, 500, 502, and NGR 05-002-160, 24-005-050, and 26-008- 001. R. Cowsik provided helpful comments on the distributed acceleration process. We are grateful to M. A. Olevitch for significant computer systems and programming assistance and to S. D. Barthelmy for discussion of relativistic rise measurements.

Attached Files

Published - 1987-19.pdf

Files

1987-19.pdf
Files (1.7 MB)
Name Size Download all
md5:a264cfe9daa6ef776f74c3a5a2a6b547
1.7 MB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 26, 2023