B. Klecker, A. Bogdanov, D. Hovestadt Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1603, D-85740 Garching, Germany R.F. Wimmer-Schweingruber, R. Schaerer Physikalisches Institut, University of Bern, CH 3012 Bern, Switzerland E. Moebius, M. A. Popecki, L. M. Kistler, , A.B. Galvin, D. Heirtzler, D. Morris Dept. of Physics and Space Science Center, University of New Hampshire, Durham, NH G. Gloeckler University of Maryland, College Park, Md, 20742, USA
With SWICS and SEPICA onboard ACE ionic charge measurements are now available for a wide energy range, covering the solar wind and suprathermal energetic particles. The high sensitivity of SEPICA has been utilized to examine the heavy ion composition and mean Fe ionic charge state as a function of time for several large, gradual, CME related solar energetic particle events. We selected for further analysis those events that clearly show small Fe/O ratios and low mean Fe ionic charge states (Q (Fe) ~ 10 - 12) throughout the event, excluding by this method a possible admixture from impulsive events. We determine for these events with SEPICA the mean ionic charge states of C, O, Ne, Mg, Si, and Fe in the energy range ~ 0.2-0.7 MeV/nuc and with SWICS the ionic charge distributions of C, O, Ne, and Fe ions of the solar wind. We find for this sample of 'pure' gradual events for suprathermal ions mean ionic charge states of, for example, ~ 6.5 (O), ~ 8 (Ne), and ~11 (Fe), generally consistent with average solar wind measurements. We will compare the suprathermal charge states with the solar wind measurements for some events where local acceleration at an interplanetary shock is observed, and where the charge states are expected to be similar or only slightly altered by the acceleration mechanism.