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Anomalous cosmic rays and solar modulation

Cummings, A. C. and Stone, E. C. (1998) Anomalous cosmic rays and solar modulation. Space Science Reviews, 83 (1-2). pp. 357-408. ISSN 0038-6308. doi:10.1023/A:1005027929871.

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We review aspects of anomalous cosmic rays (ACRs) that bear on the solar modulation of energetic particles in the heliosphere. We show that the latitudinal and radial gradients of these particles exhibit a 22-year periodicity in concert with the reversal of the Sun's magnetic field. The power-law index of the low energy portion of the energy spectrum of ACRs at the shock in 1996 appears to be ≤ -1.3, suggesting that the strength of the solar wind termination shock at the helioequatorial plane is relatively weak, with s ≤ 2.8. The rigidity dependence of the perpendicular interplanetary mean free path in the outer heliosphere for particles with rigidities between ∼ 0.2 and 0.7 GV varies approximately as R^2, where R is particle rigidity. There is evidence that ACR oxygen is primarily multiply charged above ∼ 20 MeV/nuc and primarily singly-charged below ∼ 16 MeV/nuc. The location of the termination shock was at ∼ 65 AU in 1987 and ∼ 85 AU in 1994.

Item Type:Article
Related URLs:
URLURL TypeDescription
Cummings, A. C.0000-0002-3840-7696
Stone, E. C.0000-0002-2010-5462
Additional Information:© 1998 Kluwer Academic Publishers. We thank J. T. Hoeksema for supplying the heliospheric neutral sheet tilt data prior to publication. This work was supported by NASA under contract NAS7-918.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:anomalous cosmic rays; Pioneer 10; SAMPEX; Voyager; solar modulation; heliosphere; solar wind termination shock; diffusion coefficient; gradients
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1997-27
Issue or Number:1-2
Record Number:CaltechAUTHORS:20140908-101152277
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Official Citation:Cummings, A. C., & Stone, E. C. (1998). Anomalous Cosmic Rays and Solar Modulation. Space Science Reviews, 83(1-2), 51-62. doi: 10.1023/a:1005057010311
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49333
Deposited On:08 Sep 2014 23:40
Last Modified:10 Nov 2021 18:42

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