Do fast protons and α particles have the same energy distributions in solar flares?

Abstract

Nuclear de-excitation γ-ray lines yield diagnostic information on ion acceleration in solar flares. Deductions using these lines of flare site ion distributions generally assume that all accelerated ion species have energy distributions of the same form. Particularly high total energy contents for fast ions result. Here we show how this assumption may be relaxed. Sufficiently precise measurements of a key set of lines may be combined to deduce separately the distributions of the fast protons and α-particles that produce the narrow de-excitation lines. We apply the resulting procedure to sets of line fluences obtained previously from SMM/GRS data. Interpretations of these data appear plausible in which comparatively small numbers of α particles are accelerated into energy distributions significantly harder than those found for protons.