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Radial and Latitudinal Gradients of Anomalous Cosmic-Ray Oxygen and Helium from 1 to ~41 AU

Cummings, A. C. and Mewaldt, R. A. and Stone, E. C. and Webber, W. R. (1990) Radial and Latitudinal Gradients of Anomalous Cosmic-Ray Oxygen and Helium from 1 to ~41 AU. In: Proceedings of the 21st International Cosmic Ray Conference. Vol.6. Department of Physics and Mathematical Physics, The University of Adelaide , Northfield, South Australia, pp. 206-209.

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We have used data from the IMP 8, Voyager 1 (VI), Voyager 2 (V2), Pioneer 11 (Pll), and Pioneer 10 (PIO) spacecraft. to determine the radial and latitudinal gradients of anomalous cosmic ray oxygen in the energy range ~7 - 25 MeV/nuc and anomalous cosmic ray helium in the energy range ~20- 25 MeV/nuc for a time period near minimum solar modulation in 1987. We find that the radial gradients of both species are decreasing functions of radial distance, r, approximately r^(-1) for oxygen and r^(-0.7) for helium. The latitudinal gradient is large and negative, implying significant spherical asymmetry in the heliospheric distribution of these particles.

Item Type:Book Section
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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:© Organizing Committee of the 21st Int. Cosmic Ray Conference. Provided by the NASA Astrophysics Data System. We thank Todd Hoeksema for providing the neutral sheet tilt data. This work was supported in part by NASA under contracts NAS-7-918 and NAG 5-727 and grant NGR-05-002-160.
Group:Space Radiation Laboratory
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Space Radiation Laboratory1989-21
Record Number:CaltechAUTHORS:20140714-155936587
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47194
Deposited By: Deborah Miles
Deposited On:21 Jul 2014 21:36
Last Modified:20 Feb 2020 14:33

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