Energy Spectra of 3He, 4He, and Heavy Ions in Impulsive Solar Energetic
Particle Events
J. E. Mazur
The Aerospace Corporation
G. M. Mason, J. R. Dwyer
University of Maryland
M. E. Wiedenbeck, P. L. Slocum
Jet Propulsion Laboratory
C. M. S. Cohen, A. C. Cummings, R. A.Leske, R. A. Mewaldt
Caltech
E. R. Christian, T. T. von Rosenvinge
NASA/Goddard Space Flight Center
R. E. Gold, S. M. Krimigis
JHU/Applied Physics Laboratory
Since the launch of the Advanced Composition Explorer (ACE) in August 1997,
numerous impulsive solar particle events have occurred, with a sharp
increase beginning in early 1998 and continuing through at least the summer
of 1999. Using the Ultra-Low-Energy Isotope Spectrometer (ULEIS) and Solar
Isotope Spectrometer (SIS) on ACE, we have measured the energy spectra of
3He, 4He and heavy ions over the range ~0.1-10 MeV/nucleon in order to
examine possible differences in the mechanisms responsible for the
characteristic enhancements of 3He and heavy ions in these events.
In some cases the 3He spectral form is significantly different from 4He,
which may provide an important new clue to the acceleration process. We
will compare the observed spectral forms with predictions from current
theories for impulsive solar particle acceleration.