Measurements of the Ionic Charge States of Solar Energetic Particles Using the Geomagnetic Field

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Abstract
The mean charge states of C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, and Ni ions with ~15-70 MeV nucleon-1 in the two large solar energetic particle (SEP) events of 1992 October 30 and November 2 have been determined using measurements of the invariant latitude of the cosmic-ray cutoffs of these elements from the Mass Spectrometer Telescope on the polar-orbiting SAMPEX satellite. The deduced charge state values are in good agreement with the mean values measured directly in previous SEP events at much lower energies of ~1 MeV nucleon-1. The inferred equilibrium source temperatures are confirmed to be typically 2 × 106 K, which provides additional evidence that SEPs in gradual-type events are accelerated coronal material.