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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

Binns, W. R. and Garrard, T. L. and Israel, M. H. and Jones, Michael D. and Kaminkowski, M. P. and Klarmann, J. and Stone, E. C. and Waddington, C. J. (1988) 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. Astrophysical Journal, 324 (2). pp. 1106-1117. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20140430-161225559

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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.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1086/165966 DOIArticle
http://adsabs.harvard.edu/doi/10.1086/165966ADSArticle
Contact Email Address:dmiles@caltech.edu
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.
Group:Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
NASANAG 8-498
NASANAG 8-500
NASANAG 8-502
NASANGR 05-002-160
NASANGR 24-005-050
NASANGR 26-008-001
Subject Keywords:cosmic rays: abundances
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1987-19
Record Number:CaltechAUTHORS:20140430-161225559
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140430-161225559
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45384
Collection:CaltechAUTHORS
Deposited By: SWORD User
Deposited On:01 May 2014 22:30
Last Modified:01 May 2014 22:30

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