HR: 14:45h
AN: SH33A-06    [Abstracts]
TI: Injection and Propagation of Shock-Associated Solar Energetic Particles
AU: * Mason, G M
EM: gmmason@umd.edu
AF: Department of Physics, University of Maryland, College park, MD 20742 United States
AU: * Mason, G M
EM: gmmason@umd.edu
AF: I.P.S.T., University of Maryland, College Park, MD 20742 United States
AU: Freeman, M S
EM: freeman@umd.edu
AF: Department of Physics, University of Maryland, College park, MD 20742 United States
AU: Desai, M I
EM: desai@uleis.umd.edu
AF: Department of Physics, University of Maryland, College park, MD 20742 United States
AU: Dwyer, J R
EM: dwyer@fit.edu
AF: Dept. Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 United States
AU: Mazur, J E
EM: Joseph.E.Mazur@aero.org
AF: The Aerospace Corporation, El Segundo Blvd., El Segundo, CA 92957 United States
AB: It has long been known that during the initial portion of shock-associated solar energetic particle (SEP) events, different species of particles sometimes show differences in the rise portion and time to maximum at 1 AU. The effect is more pronounced at energies below a few MeV/nucleon. Under the paradigm that SEPs are all accelerated in a single stage near the Sun, this behavior has been modeled by invoking a rigidity dependence of the interplanetary scattering mean free path. Using the more recent paradigm that shock-associated SEPs are accelerated over a considerable spatial scale of perhaps distances of up to 10s of solar radii, these differences in the onset and rise to maximum may be due to the effects of acceleration and release time scales at the shock, with little influence from interplanetary propagation. Distinguishing between these two paradigms is important for understanding and correctly modeling SEPs. ACE spacecraft observations for large particle events during the recent solar maximum have made it possible to re-visit this problem over a broader energy range and with greater sensitivity than hitherto possible. The current study examines whether ACE observations are consistent with a simple model of particle release at the Sun over a finite period, followed by interplanetary propagation. By using multiple species and a broad energy range, we can investigate whether such a simple model can fit the data for typical events.
DE: 7513 Coronal mass ejections
DE: 7514 Energetic particles (2114)
DE: 7807 Charged particle motion and acceleration
DE: 7851 Shock waves
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2005 Joint Assembly