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Sharply concentrated cosmic-ray excess fluxes from heliomagnetospheric nose and tail boundaries observed with neutron monitors on the ground

Earth, Planets and Space volume 57, pages 1083–1091 (2005)Cite this article

Abstract

Two kinds of sharply concentrated excess flux of cosmic rays from heliomagnetospheric nose and tail directions (right ascension α ∼ 18 hours and ∼ 6 hours) are found by the analysis of sidereal daily variation of neutron intensity (median energy Em ∼ 20 GeV) on the ground. These fluxes do not show any response to the polarity reversal of solar magnetic field at the north pole and is contradictory to the simulation of the solar modulation of galactic anisotropy, which produces sidereal variation at the Earth greater in the negative polarity state than in the positive state. This indicates that they are not of the galactic origin and would be produced on the heliomagnetospheric nose and tail boundaries where it is considered that the interaction between the galactic and solar magnetic fields could produce the cosmic-ray acceleration. The acceleration mechanism producing the polarity-independent sidereal variation against solar modulation will be discussed.

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Authors and Affiliations

  1. Solar-Terrestrial Environment Laboratory, Nagoya University, Chikusa-ku, Nagoya, 464-8601, Japan

    K. Nagashima & Z. Fujii

  2. Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashinoha, Kashiwa, 277-8582, Japan

    I. Kondo

Authors
  1. K. Nagashima
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  2. I. Kondo
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  3. Z. Fujii
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Correspondence to I. Kondo.

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Nagashima, K., Kondo, I. & Fujii, Z. Sharply concentrated cosmic-ray excess fluxes from heliomagnetospheric nose and tail boundaries observed with neutron monitors on the ground. Earth Planet Sp 57, 1083–1091 (2005). https://doi.org/10.1186/BF03351887

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