HR: 16:45h
AN: SH44C-04    [Abstracts]
TI: Evidence for Mass-per-charge dependent acceleration of a multiple-component seed population by CME-driven interplanetary shocks near 1 AU
AU: * Allegrini, F
EM: fallegrini@swri.edu
AF: Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228, United States
AU: Desai, M I
EM: mdesai@swri.edu
AF: Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228, United States
AU: Mason, G M
EM: Glenn.Mason@jhuapl.edu
AF: The Johns Hopkins University, Applied Physics Laboratory Johns Hopkins Rd, Laurel, MD 20723, United States
AU: Kucharek, H
EM: Harald.Kucharek@unh.edu
AF: University of New Hampshire, Morse Hall 39 College Road, Durham, NH 03824, United States
AU: Moebius, E
EM: eberhard.moebius@unh.edu
AF: University of New Hampshire, Morse Hall 39 College Road, Durham, NH 03824, United States
AB: Using measurements from the ULEIS and SEPICA instruments on board the Advanced Composition Explorer between November 1997 and October 2000 we have surveyed the abundances of 0.25-0.8 MeV nucleon-1 He+, 3He, and heavy ions from C to Fe during 18 CME-driven interplanetary (IP) shocks observed near 1 AU. Our results show that each of the 18 IP shocks is accompanied by enhancements in the intensities of both 3He and He+ ions. In addition we find that, on a case-by-case basis, the abundances of He+ and the heavier elements such C to Fe (but not 3He) are depleted systematically as a function of the ion's M/Q ratio when compared with those measured in the ambient suprathermal ion population upstream of the IP shocks. These results show for the first time that individual IP shocks routinely accelerate ions from multiple seed populations such as multiples SEP events, CIRs, pick-up ions, etc., via systematic rigidity-dependent acceleration processes where ions with higher rigidity or M/Q ratios are accelerated less efficiently than those with lower M/Q ratios. We also compare the M/Q-dependent depletion of these abundances with the locally measured shock parameters and explore why the 3He abundance does not fit into the systematic M/Q-charge dependent fractionation processes.
DE: 2101 Coronal mass ejections (7513)
DE: 2114 Energetic particles (7514)
DE: 2139 Interplanetary shocks
DE: 2152 Pickup ions
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting