Heavy Ion Acceleration beyond 10 M[CLC]e[/CLC]V per Nucleon in Impulsive Solar Flares

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Abstract
We present the energy spectra of 0.5-9 MeV nucleon-14He and ~0.5-20 MeV nucleon-1 O, Ne-Si, and Fe observed in impulsive flares with instrumentation on board the SAMPEX satellite between 1992 July and 1994 July. With the large collecting power of this instrumentation, we routinely find O, Ne-Si, and Fe ions accelerated in impulsive flares up to energies of ~16 MeV nucleon-1 and have observed Fe accelerated up to between 20 and 28 MeV nucleon-1. These are the highest energies of heavy ions observed in typical impulsive flares to date, and they provide an important constraint on acceleration theories. The majority of events have spectra that are power laws in energy for 4He, O, Ne-Si, and Fe.