30TH INTERNATIONAL COSMIC RAY CONFERENCE Ionic charge states of heavy ions associated with interplanetary shocks at 1AU

Abstract: Measurements with advanced instrumentation on the SAMPEX, SOHO and ACE space-craft show a large variability of the ionic charge of heavy ions in solar energetic particle (SEP) events with energy, in particular for Fe. In this paper we present a survey of ionic charge observations in in-terplanetary shock related SEP events obtained with the SEPICA instrument onboard ACE in the en-ergy range ~0.18-0.43 MeV/nuc during the time period 1997- 2000. We analyzed all interplanetary shock related events where SEPICA data are available. We find for most of the events for iron in the energy range 0.18- 0.25 MeV/nuc mean ionic charge states of ~9- 11, with a significant increase of QFe between 0.18 and 0.43 MeV/nuc in only 3 of 35 cases. Two of these 3 events show high charge states for Fe (~16) at 0.18- 0.25 MeV/nuc with a strong increase by 3- 4 charge units between 0.18 and 0.43 MeV/nuc, similar to the observations in all Fe-rich and 3He-rich events. For the majority of the events (32 of 35) the mean ionic charge is independent of energy in the energy range 0.18-0.43 MeV/nuc and consistent with typical charge states of iron in the solar wind and in suprathermal parti-cles