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Observations of Anomalous Cosmic Rays in the Heliosphere from the SAMPEX, Ulysses, Voyager, and Pioneer Spacecraft

Cummings, A. C. and Cummings, J. R. and Mewaldt, R. A. and Stone, E. C. and Blake, B. and Fräenz, M. and Klecker, B. and Hovestadt, D. and Webber, W. R. (1995) Observations of Anomalous Cosmic Rays in the Heliosphere from the SAMPEX, Ulysses, Voyager, and Pioneer Spacecraft. Advances in Space Research, 16 (9). p. 337. ISSN 0273-1177. doi:10.1016/0273-1177(95)00357-K.

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The radial and latitudinal gradients of anomalous cosmic rays (ACRs) in the heliosphere are expected to depend on the phase of the solar cycle. During the last solar minimum in 1987, when positive energetic particles were entering the heliosphere along the neutral current sheet, the radial gradient of these particles in the outer heliosphere was found to depend on the tilt of the sheet and was a minimum when the tilt assumed its minimum value. The latitudinal gradient was large and negative during this same period. On a large scale, the radial gradient from l to -40 AU was found to decrease linearly with radial distance for ACR oxygen. These particle distributions are expected to be different after the polarity reversal of the solar magnetic field, which occurred -1990. By July 1994, the Voyagers 1 and 2 (Vl and V2) and Pioneer 10 (PlO) spacecraft will be positioned in the outer heliosphere in the radial range 45 to 62 AU. V2 and PlO will be at relatively low heliographic latitudes, while V l will be at 32° N. In the inner heliosphere Ulysses will be beyond 70° S at a radial distance of 2.7 AU. The SAMPEX spacecraft is in a near-polar Earth orbit. Using measurements of anomalous cosmic rays from instruments on these 5 spacecraft, we will report on the temporal behavior of the fluxes and their radial and latitudinal gradients during the current approach towards solar minimum. We will compare the results from those taken during the last solar minimum period and relate these to current models of solar modulation.

Item Type:Article
Related URLs:
URLURL TypeDescription
Cummings, A. C.0000-0002-3840-7696
Mewaldt, R. A.0000-0003-2178-9111
Stone, E. C.0000-0002-2010-5462
Additional Information:Copyright © 1995 COSPAR.
Group:Space Radiation Laboratory
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1995-12
Issue or Number:9
Record Number:CaltechAUTHORS:20140612-132930616
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46247
Deposited By: Deborah Miles
Deposited On:12 Jun 2014 22:12
Last Modified:10 Nov 2021 17:23

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