Measurements of the ionic charge states of solar energetic particles at 15–70 MeV/nucleon using the geomagnetic field

Abstract

The mean charge states of abundant heavy ions with ∼15–70 MeV nucleon ^(−1) in the two large solar energetic particle events of 1992 October 30 and November 2 have been determined using measurements of the invariant latitude of the cosmic ray geomagnetic cutoffs as a function of time, particle energy, and element 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 solar energetic particle events at much lower energies of ∼1 MeV nucleon ^(−1), with inferred equilibrium source temperatures of typically 2×10^6 K. This result provides additional evidence that solar energetic particles in gradual‐type events consist of accelerated coronal material.