Mean Ionic Charge States in Large Solar Energetic Particle (SEP) Events

Posted September 4, 2007

From: Allan Labrador, Caltech

Ionic charge states are useful probes of source materials and conditions, as well as conditions of acceleration and transport for solar energetic particles. The MAST experiment aboard SAMPEX employs a geomagnetic rigidity filter technique to provide direct measurements of mean ionic charge states in large solar energetic particle (SEP) events, for elements from N to Fe and energies up to 00 MeV/nuc. The technique has been described in Leske et al. (1995). These measurements can be used in multi-spacecraft studies to examine, for example, the source of materials accelerated in coronal mass ejections (CMEs).

SAMPEX/MAST Q-states are provided by the SAMPEX Data Center in table form in an Excel spreadsheet. Each row in the table corresponds to a large SEP event, and each element in the row corresponds to a measured mean ionic charge state and measurement uncertainty for N, O, Ne, Mg, Si, and Fe, at energies up to ~100 MeV/nuc. References for the measurements are also listed in the table. When the geomagnetic rigidity filter technique is unable to return a charge state, the result in the table is left blank. Some listed SEP events are currently under review prior to final publication; these measurements are listed as "pending."

The available charge state measurements (Q(Z)) are also given as Q vs. Z plots for each SEP event. The plots include best-fits to the data for ionic charge state vs. plasma temperature, using calculations by Mazzotta et al. (1998). These fits are shown as solid lines, along with the plasma temperature derived from the fit. The dotted line shown in each plot corresponds to fully-stripped ions.

• Data in Excel spreadsheet format.
• Q vs. Z plot for 1992 Oct 30 event
• Q vs. Z plot for 1992 Nov 03 event
• Q vs. Z plot for 1997 Nov 06 event
• Q vs. Z plot for 1998 Aug 25 event
• Q vs. Z plot for 1998 Sep 30 event
• Q vs. Z plot for 1998 Nov 14 event
• Q vs. Z plot for 2000 Jul 14 event

References

Leske, R. A., Cummings, J. R., Mewaldt, R. A., Stone, E. C., and von Rosenvinge, T. T., Astrophys. J. Lett., 452, L149-L152 (1995).

Mazzotta et al., Astron. Astrophys. Suppl. Ser. 133, 403 (1998).