The Ionic Charge of Solar Energetic Particles with Energies of 0.3-70 MeV per Nucleon

With the three particle sensors Low Energy Ion Composition Analyzer (LICA), Heavy Ion Large Area Proportional Counter Telescope (HILT), and Mass Spectrometer Telescope (MAST) on board the polar-orbiting Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite, the ionic charge of solar energetic particles (SEP) was measured over a wide energy range from 0.3 to 70 MeV per nucleon. For each sensor, the evaluation was performed separately. The results obtained with LICA (0.3-10 MeV per nucleon) and MAST (15-70 MeV per nucleon) were published earlier by Mason et al. and Leske et al., respectively. In this work we present the results of the HILT sensor (7-50 MeV per nucleon) and discuss the combined results of the three instruments.

With HILT, the mean ionic charge of SEP was measured for carbon, nitrogen, oxygen, neon, magnesium, silicon, sulfur, argon, calcium, and iron in the energy range 7-50 MeV per nucleon during two consecutive large SEP events in 1992 October-November. The mean ionic charge was inferred from the rigidity-dependent geomagnetic flux cutoff. The coronal temperatures deduced from the mean ionic charges are well in accordance with the value of ~2 × 10⁶ K except for neon and magnesium, as previously reported.

The data measured with the three sensors, LICA, HILT, and MAST, agree well and are in accordance with data previously measured at energies below 3 MeV per nucleon (Luhn et al.), except for iron, where we observed a significant energy dependence of the mean charge over the energy range 0.3-70 MeV per nucleon.