Energy dependence of the ionic charge state distribution during the November 1997 solar energetic particle event

Abstract

Ionic charge state distributions for a variety of species, such as C, O, Ne, Mg, Si and Fe were obtained with the Solar Energetic Particle Ionic Charge Analyzer (SEPICA) on ACE for the strongest of a series of energetic particle events after the November 4 and 7, 1997, flares. The capabilities of SEPICA allow a much more detailed analysis of the charge distributions than previous instrumentation. Over the energy range from ≈ 0.2 to 1 MeV/Nuc a trend is observed that shows charge states increasing with energy, in particular for Mg, Si and Fe. In addition, for Fe a mixed charge state distribution with a distinct peak at lower charge states (10–14) is observed simultaneously with a tail reaching to charge states up to ≈ 20. This may be an indication of a mixture of different energetic particle populations.