Heidelberg 2006 – wissenschaftliches Programm
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EP: Extraterrestrische Physik
EP 18: Sonne: Energetische Teilchen, Sonnenwind und CMEs
EP 18.2: Fachvortrag
Donnerstag, 16. März 2006, 11:30–11:45, B
Velocity ditribution functions of solar wind ions from ACE/SWICS using a maximum likelihood analysis technique — •Lars Berger1, Muharrem Köten1, Jim Raines2, Robert F. Wimmer-Schweingruber1, and Thomas H. Zurbuchen2 — 1Institut für Experimentelle und Angewandte Physik, University of Kiel, D-24098 Kiel, Germany — 2University of Michigan, Atmospheric, Oceanic, and Space Sciences 2455 Hayward St., Ann Arbor, MI 48109, USA
By studying the velocity distribution of solar wind ions we can learn a lot about the acceleration processes in the inner heliosphere. The shape of the distribution can help us to distinguish between heating by coulomb-interaction and wave-heating. Previous studies have shown that the velocity distribution of solar wind ions follows a thermal(maxwellian) distribution extended with a superthermal tail. These superthermal ions are rare and former analysis techniques have great uncertainties applied to them. We have analysed data from the solar wind ion spectrometer(SWICS) on the advanced composition explorer(ACE) using a maximum likelihood analysis technique based on poissonian statistics, to improve the results especially for low count rates. We present results for different solar wind types.