Entry of Energetic Solar Protons into the Tail

Abstract

A number of studies have been made recently of the intensities of particles over the polar caps during solar events in order to investigate properties of the magnetosphere (e.g., Krimigis et al., 1967’; Evans and Stone, 1969; Williams and Bostrom, 1969; Van Allen et al., 1971). Most of these investigations have been confined to relatively low energy particles. During the solar events of November 18, 1968, and February 25, 1969, large interplanetary anisotropics were observed in the flux of high energy protons. At the same time a detector of 90 to 360 MeV protons aboard the low altitude polar orbiting satellite ESRO 2 measured heavy structure over the north and south polar caps. The higher energy range of the proton measurements lends itself more readily to investigation by trajectory integration methods, and these have been used here in an attempt to link the structure with the interplanetary anisotropy and hence deduce the penetration mechanisms.