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Effects of Solar Modulation on the Low-Energy Cosmic Ray Antiproton/Proton Ratio

Labrador, A. W. and Mewaldt, R. A. (1996) Effects of Solar Modulation on the Low-Energy Cosmic Ray Antiproton/Proton Ratio. Astrophysical Journal, 480 (1). pp. 371-374. ISSN 0004-637X. doi:10.1086/303960.

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We examine the transport of cosmic-ray protons and anitprotons from local interstellar space through the interplanetary medium to Earth and discuss the resulting effects on the low-energy antiproton/proton ratio at 1 AU. We find that the antiproton/proton ratio at energies above ~3 GeV is a useful diagnostic of cosmic-ray transport in the Galaxy. However, at energies below ~1 GeV the expected ratio is much more uncertain because of differences in the energy spectra and the resulting relative modulation of protons and antiprotons over the solar cycle, as well as uncertainties in the interstellar spectra. Using calculated interstellar spectra as references, we find that the antiproton/proton ratio at low energies varies by as much as an order of magnitude over the solar cycle. As a result, we recommend that attention be given instead to interpretation of the measured cosmic-ray antiproton energy spectrum rather than to the antiproton/proton ratio.

Item Type:Article
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URLURL TypeDescription
Labrador, A. W.0000-0001-9178-5349
Mewaldt, R. A.0000-0003-2178-9111
Additional Information:© 1997. The American Astronomical Society. Received 1996 July 26; accepted 1996 November 12. This work was funded by NASA under grant NAGW-1919. One of us (A. L.) is grateful for a NASA Graduate Fellowship. We thank F. McDonald, W. McGuire, and P. Schuster for providing us with IMP 8 proton data. We thank T. Gaisser, R. Schaefer, E. Stone, R. Streitmatter, and W. R. Webber for useful discussions.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
NASA Graduate FellowshipUNSPECIFIED
Subject Keywords:cosmic rays—interplanetary medium
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1996-25
Issue or Number:1
Record Number:CaltechAUTHORS:20140703-220710670
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46841
Deposited By: Deborah Miles
Deposited On:23 Jul 2014 17:43
Last Modified:10 Nov 2021 17:30

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