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Published January 15, 1999 | Published
Journal Article Open

Charge States of Solar Energetic Particles Using the Geomagnetic Cutoff Technique: SAMPEX Measurements in the 6 November 1997 Solar Particle Event


We report on the ionization states of ∼0.5–50 MeV/nucleon ions in the 6 November 1997 solar particle event using instrumentation on the SAMPEX satellite and the geomagnetic cutoff technique. Using the geomagnetic cutoffs of ∼10 MeV 4He and ∼20 MeV protons, we infer the ionization states of ∼0.5–50 MeV/nucleon C-Fe by measuring their latitude distributions. The geomagnetic cutoff method extends the measurement of ionization states beyond 10 MeV/nucleon, where charge state information is inaccessible with present electrostatic deflection techniques. In contrast to an increase of the Fe charge state observed above ∼20 MeV/nucleon in events in late 1992, we find in the 6 November 1997 event that Si & Fe charge states increased dramatically across 0.5–50 MeV/nucleon. While the origin of this newly discovered energy dependence is unknown, such significant event to event variations of solar particle charge states should be considered in models of acceleration and transport processes.

Additional Information

Copyright 1999 by the American Geophysical Union. Article first published online: 7 DEC 2012 We thank the members of the SAMPEX instrument teams who have contributed to the success of the SAMPEX mission, as well as the personnel at the Goddard Space Flight Center who constructed, launched, and operate the SAMPEX spacecraft. NASA grant NAS5-2963 supported this work.

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