HR: 17:30h
AN: SH44C-07    [Abstracts]
TI: The Trapping of Low-Energy Particles by Interplanetary Shocks
AU: * Al Dayeh, M
EM: maldayeh@gmail.com
AF: Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, United States
AU: * Al Dayeh, M
EM: maldayeh@gmail.com
AF: Florida Institute of Technology, 150 W University Boulevard, Melbourne, FL 32901, United States
AU: Dwyer, J
EM: jdwyer@fit.edu
AF: Florida Institute of Technology, 150 W University Boulevard, Melbourne, FL 32901, United States
AU: Rassoul, H
EM: rassoul@fit.edu
AF: Florida Institute of Technology, 150 W University Boulevard, Melbourne, FL 32901, United States
AU: Mason, G
EM: glenn.mason@jhuapl.edu
AF: The Johns Hopkins University/Applied Physics Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723, United States
AU: Mazur, J
EM: Joseph.E.Mazur@aero.org
AF: The Aerospace Corporation, 15049 Conference Center Drive, CH3/210, Chantilly, VA 20151, United States
AU: Desai, M
EM: mdesai@swri.edu
AF: Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, United States
AB: Using ~0.045-10 MeV/nucleon ion data from ACE/ULEIS, we have found that a substantial number of shock- associated solar energetic particle events (20 events) have significant delays in the arrival of the low-energy component beyond what is expected from the travel time of energetic particles from the sun to the earth at 1 AU. Indeed, for some events, after correcting for the velocity dispersion, the low energy component (E < 0.1 MeV/nucleon) is almost completely absent while the high-energy component (E > 1 MeV/nucleon) has very large enhancements. SEP events with the most dramatic initial depletion of low-energy particles are accompanied by large proton fluxes and have large enhancements of the low-energy particles later, in coincidence with the arrival of the interplanetary shock, a day or two after the start of the event. In addition, these events show Fe/O enhancements during the periods in which the low-energy component is depleted and lower Fe/O values once the shock arrives. These new observations appear to be explained by the trapping of particles with low energy-to-charge (E/Q) ratios in the vicinity of the shock by magnetohydrodynamic waves, possibly generated by high energy protons streaming along the magnetic field lines.
DE: 7514 Energetic particles (2114)
DE: 7845 Particle acceleration
DE: 7851 Shock waves (4455)
DE: 7867 Wave/particle interactions (2483, 6984)
DE: 7924 Forecasting (2722)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting