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Charge states of solar energetic particles using the geomagnetic cutoff technique: SAMPEX measurements in the 6 November 1997 solar particle event
Author(s) -
Mazur J. E.,
Mason G. M.,
Looper M. D.,
Leske R. A.,
Mewaldt R. A.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1998gl900075
Subject(s) - physics , solar energetic particles , earth's magnetic field , nucleon , ionization , neutron monitor , cosmic ray , coronal mass ejection , nuclear physics , charged particle , event (particle physics) , atomic physics , solar flare , computational physics , ion , solar wind , astrophysics , magnetic field , plasma , quantum mechanics
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 4 He 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.