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Anomalous Cosmic Rays and Solar Modulation

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Cosmic Rays in the Heliosphere

Part of the book series: Space Sciences Series of ISSI ((SSSI,volume 3))

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Abstract

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 asR 2, whereRis particle rigidity. There is evidence that ACR oxygen is primarily multiply charged above ~ 20 MeV/nuc and primarily singly-charged below ti 16 MeV/nuc. The location of the termination shock was at ~ 65 AU in 1987 and ~ 85 AU in 1994.

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Authors and Affiliations

  1. California Institute of Technology, Pasadena, CA, 91125, USA

    A. C. Cummings & E. C. Stone

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  1. A. C. Cummings
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  2. E. C. Stone
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Editor information

Editors and Affiliations

  1. Department of Oceanic, Atmospheric, and Space Sciences, University of Michigan, 48109, Ann Arbor, MI, USA

    L. A. Fisk

  2. Lunar and Planetary Laboratory, University of Arizona, 85721, Tucson, AZ, USA

    J. R. Jokipii

  3. School of Physics and Astronomy, University of Birmingham, B15 2TT, UK

    G. M. Simnett

  4. International Space Science Institute, CH-3012, Bern, Switzerland

    R. von Steiger

  5. Space Science Department of ESA, ESTEC, NL-2200 AG, Noordwijk, The Netherlands

    K.-P. Wenzel

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© 1998 Springer Science+Business Media Dordrecht

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Cummings, A.C., Stone, E.C. (1998). Anomalous Cosmic Rays and Solar Modulation. In: Fisk, L.A., Jokipii, J.R., Simnett, G.M., von Steiger, R., Wenzel, KP. (eds) Cosmic Rays in the Heliosphere. Space Sciences Series of ISSI, vol 3. Springer, Dordrecht. https://doi.org/10.1007/978-94-017-1189-0_5

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  • DOI: https://doi.org/10.1007/978-94-017-1189-0_5

  • Publisher Name: Springer, Dordrecht

  • Print ISBN: 978-90-481-5032-8

  • Online ISBN: 978-94-017-1189-0

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