Ground-level enhancement of solar cosmic rays on October 28, 2003: A mechanism of the generation of particles in the sun

In order to reveal mechanisms of the generation of solar cosmic rays, the spectrum of an event of the groundlevel enhancement on October 28, 2003 (the GLE65 event) in a maximally wide energy range has been analyzed using direct measurements of solar particle fluxes on the ACE, GOES, and WIND spacecrafts, as well as measurements on the worldwide network of neutron monitors. The spectrum in the relativistic energy range has been estimated within the previously proposed “effective-energy method”. In this method, each ground-based instrument is assigned the corresponding effective momentum (or energy) of primary particles at which the flux of solar cosmic rays is determined. The effective momentum is chosen such that errors in the determination of the solar-particle spectrum are minimized. It has been shown that the error of the estimate of the effective momentum within the proposed method for the determination of solar-particle fluxes is no more than 20 MeV/c. It has been found that the spectrum of solar cosmic rays from the event under study measured in the orbit of the Earth extends from $\approx$40 keV to $\approx$5 GeV and is described by a power law with an exponential cutoff at relativistic energies. A quasilinear theory of the regular acceleration of charged particles by shock waves in the lower corona of the Sun, which was developed at the Shafer Institute of Cosmophysical Research and Aeronomy, Siberian Branch, Russian Academy of Sciences, has been used to reveal the nature of solar cosmic rays. It has been shown that the acceleration of solar cosmic rays on the front of a coronal shock wave in the event under study ended at a distance of no longer than four radii of the Sun.