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Elemental Fractionation In Small Solar Energetic Particle Events, Penny L. Slocum, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

Using the Solar Isotope Spectrometer on the Advanced Composition Explorer (ACE), we have measured the 11.0-21.8 MeV nucleon-1 heavy (Z ≥ 6) element abundances of 39 small solar energetic particle (SEP) events that occurred between 1998 April 3 and 2002 February 26. Using He isotope data from the UltraLow-Energy Isotope Spectrometer on ACE, we have classified the events according to their 0.5-2.0 MeV nucleonˉ¹ ³He/⁴He ratios. We find that their average heavy-element composition is similar to that of either large gradual events or ³He-rich events, depending on their ³He/⁴He ratio. As seen in recent studies of small SEP events, we …