### Abstract

The dynamics of the proton energy spectrum during the solar cycle is studied. The spectra were determined by 1-100 MeV particle fluxes measured by different instruments mounted aboard the Earth's IMP-8 satellite for more than one hundred quiet-time intervals in the period between 1974 and 1991. The galactic branch of the spectra (E_{p} > 10 MeV) constructed for every quiet interval was fitted by a power law function, J = CE^{v}. The theory predicts that in the 1-100 MeV energy range, where the adiabatic cooling of particles is dominant, 〈v〉 = 1, while we have derived a v double-peak distribution. The main maximum has the mean value (v) = 1.35. The mean value of the second, much weaker maximum, is 〈v〉 = 0.95. Within the main maximum, v values are distributed in accordance with the Gaussian law with a standard deviation 〈D/〉v) = 0.12. The substantial difference of v from unity requires the elaboration of a new model of modulation processes in the inner heliosphere. The v values corresponding to the second maximum show that modulation processes correspond sometimes to theoretical conceptions. It is shown that v correlates weakly with parameters A and γ describing the solar branch of the spectrum (J(E) = AE^{-γ}). At the same time, a more significant correlation is observed between v and the solar activity index, R_{z}, the counting rate of the Deep River neutron monitor, and the energy value in the minimum of the energy spectrum flux, E_{min}.

Original language | English |
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Pages (from-to) | 13-18 |

Number of pages | 6 |

Journal | Cosmic Research |

Volume | 41 |

Issue number | 1 |

DOIs | |

Publication status | Published - Jan 1 2003 |

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### ASJC Scopus subject areas

- Aerospace Engineering
- Astronomy and Astrophysics
- Space and Planetary Science

### Cite this

*Cosmic Research*,

*41*(1), 13-18. https://doi.org/10.1023/A:1022395311635