High-Energy Solar Fe Ions in the 29 September 1989 Ground Level Event
Abstract
Lovell, Duldig, and Humble (1998) have recently published a detailed analysis of the world-wide neutron monitor network's response in the 29 September 1989 Ground-Level Event (GLE). We compare their proton spectra to simultaneous measurements of solar Fe ions at tilde 50 - 1000 MeV/nuc from the University of Chicago's Cosmic Ray Nuclear Composition (CRNC) Experiment on IMP-8. These measurements revealed the hardest spectrum of high-energy solar Fe ions ever observed. When examined as a function of rigidity, the Fe nuclei do not appear to be sufficiently numerous to complicate interpretation of the neutron-monitor results, even after accounting for their partially-ionized charge state (tilde 14). However, at very high total energies, the Fe spectrum is much harder than the proton spectrum, and protons and Fe appear to make comparable contributions to the so-called "all-particle" spectrum. Thus, CME-driven shock acceleration in this very large solar particle event may be producing the same spectral differences and evolution in composition which are believed to be caused by supernova-shock acceleration at the knee of the Galactic cosmic ray spectrum.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1999
- Accession Number
- ADA602308
Entities
People
- Allan J. Tylka
- Clifford Lopate
- D. V. Reames
- William F. Dietrich
Organizations
- United States Naval Research Laboratory