A Possible Mechanism for Enriching Heavy Ions in 3He-rich Solar Energetic Particle Events

We present a mechanism to produce a seed population enriched in heavy ions as observed in 3He-rich solar energetic particle (SEP) events. If an initial particle population following a power law in energy/nucleon passes through a small amount of material, the greater affinity of heavier ions for electron pick-up below the dE/dx Bragg peak results in their penetrating the material more easily. This results in an enhancement of heavy ions in the particle population that just barely penetrates the material. The bulk of the seed particles fall in the energy range of 10s of keV/nucleon. It is supposed that some further process then energizes this seed population to produce the particles observed in interplanetary space. We find a broad range of parameters which produce enhancements comparable to Fe/O 8 as commonly observed in 3He-rich SEP events. Possible implications for the location of these events in the corona are briefly discussed.