ENERGY DEPENDENCE OF ION CHARGE STATES IN CME RELATED SOLAR ENERGETIC
PARTICLE EVENTS OBSERVED WITH ACE/SEPICA AND SOHO/STOF
A.T. Bogdanov1, B. Klecker1, E. Moebius2,
M. Hilchenbach3, L.M. Kistler2, M.A. Popecki2, D. Hovestadt1
1 Max-Planck-Institut fuer extraterrestrische Physik, Garching, D-85740, Germany,
2 Space Science Center, University of New Hampshire, Durham, NH, 03824, USA
3 Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau, D-37189, Germany
We investigate the energy dependence of the charge states of heavy ions during a number of gradual
solar energetic particle events related to coronal mass ejections. The data of two instruments with
complementary energy ranges, the Solar Energetic Particle Ionic Charge Analyzer SEPICA on ACE and
the time-of-flight mass and charge spectrometer STOF on SOHO are used to cover the energy range
from ~ 0.02 to 0.7 MeV/amu for O and Fe. Measurements with SAMPEX and SEPICA/ACE have delivered
evidence that some gradual CME related SEP events show energy dependent charge distributions. In
the present paper we are closing the gap in the lower energy interval (STOF data) thus making future
comparison to solar wind values - representative for coronal conditions - more reliable. The results
from such a comparison could contribute decisively to assessing the applicability of available stationary
and non-stationary models of the formation of the charge distributions. Also, fitting the data to results
of model calculations could be used as a source of information on the temperature and density of the
coronal plasma in the acceleration region, as well as a test for the current theoretical understanding
of the selection and acceleration mechanisms in CME related solar energetic particle events