SH54A-1519 

Study of the Coronal Source of Energetic Particles Detected in a Radio-CME and In-situ Near the Earth

* Pick, M (monique.pick@obspm.fr), Observatoire de Paris, Observatoire de Meudon Place Jansen, Meudon, 92190, France Maia, D (dmaia@fc.up.pt), Observatorio Astronomico, University of Porto, Vila Nova de Gaia, Vila Nova, 4430-146, Portugal

The energetic particle event which occurred on 2001 April 15 was associated with a white light CME and with fast expanding radio loops ("the radio CME"). In a former paper, Maia et al., 2007 showed that the electrons producing the radio emission inside the loops have energies comparable to the ones detected in situ near the Earth. Moreover, the onset of the particle release and its duration are similar for the radio loops and for the in-situ electron event. We concluded that this particle event has a coronal origin in agreement with the fact that published composition studies showed that this event contains some fraction of "flare" particles. We present a detailed study of the coronal source in which the energetic particles, detected in the corona and in- situ, take their origin. We combine the EUV Trace and Halpha imaging observations with multi-frequency radio images (432-150 MHz) which correspond at different levels in the corona. We discuss how the same population of particles can be injected both in close magnetic loops and open field lines; we compare the characteristics of this sources with those found for the 3He- rich particle events.

SH54A-1520 

The Origin of Low Energy 3He

* de Nolfo, G A (georgia@milkyway.gsfc.nasa.gov), CRESST/UMBC & NASA/GSFC, Code 661, Building 2, Greenbelt, MD 20771, United States Wiedenbeck, M E (Mark.E.Wiedenbeck@jpl.nasa.gov), Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, United States Binns, W R (wrb@wuphys.wustl.edu), Department of Physics & McDonnell Center for Space Sci., Washington University, St. Louis, MO 63130, United States Cohen, C M (cohen@srl.caltech.edu), Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125, United States Cummings, A C (ace@srl.caltech.edu), Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125, United States Israel, M H (mhi@wuphys.wustl.edu), Department of Physics & McDonnell Center for Space Sci., Washington University, St. Louis, MO 63130, United States Leske, R A (ral@srl.caltech.edu), Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125, United States Mewaldt, R A (rmewaldt@srl.caltech.edu), Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125, United States Stone, E C (ecs@srl.caltech.edu), Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125, United States von Rosenvinge, T T (tycho@milkyway.gsfc.nasa.gov), CRESST/UMBC & NASA/GSFC, Code 661, Building 2, Greenbelt, MD 20771, United States

Energetic ³He in local interplanetary space is expected to originate predominantly from the Sun and the Galaxy. Using solar quiet-time observations of ³He over a wide energy range, it is possible to study the distinct spectral shapes of the two different populations. Preliminary results suggest that at low energies of ~5 Mev/nuc, the origin of ³He is dominated by impulsive solar energetic particle events. However, above a transition energy of ~15 MeV/nuc, the galactic component appears to dominate. We present quiet-time ³He and ⁴He observations over a solar cycle from the Cosmic Ray Isotope Spectrometer (CRIS) on ACE and compare these results with low energy observations from the Solar Isotope Spectrometer (SIS) in order to ascertain the origins of low energy (~5-100 MeV/nuc) ³He.

SH54A-1521 

First results on impulsive SEP events from the STEREO IMPACT Suprathermal Electron (STE) Instrument

* Wang, L (windsound@ssl.berkeley.edu), Space Sciences Lab, UC Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450, United States * Wang, L (windsound@ssl.berkeley.edu), Physics Department, UC Berkeley, 366 LeConte Hall MC 7300, Berkeley, CA 94720-7300, United States Lin, R P), Space Sciences Lab, UC Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450, United States Lin, R P), Physics Department, UC Berkeley, 366 LeConte Hall MC 7300, Berkeley, CA 94720-7300, United States Luhmann, J), Space Sciences Lab, UC Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450, United States

The Suprathermal Electron (STE) instrument, part of the IMPACT investigation on both STEREO spacecrafts, is designed to measure electrons from ~2 to ~100 keV, with about 2 orders of magnitude increase in sensitivity over previous measurements below ~20 keV. Here, we will report the first results on solar energetic particle events (SEPs) from the STE instrument. We identify eight impulsive SEPs observed with a clear velocity dispersion by downstream STE detectors from November 2006 to August 2007. We will study the timing, energy spectrum and pitch angle distribution of those SEPs. Finally, we will compare them with WIND/3DP observations.

Author(s) (2007), Title, Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract #####-##.