Directionality of Solar Flare Accelerated Protons and Alpha Particles from Gamma-Ray Line Measurements
Abstract
The energies and widths of gamma-ray lines emitted by ambient nuclei excited by flare-accelerated protons and a particles provide information on the ions directionality and spectra, and on the characteristics of the interaction region. We have measured the energies and widths of strong lines from de-excitations of (expn 12)C (expn 16)O, and (expn 200Ne in solar flares as a function of heliocentric angle. The line energies from all three nuclei exhibit ~1% redshifts for flares at small heliocentric angles, but are not shifted near the limb. The lines have widths of ~3% FWHM. We compare the (expn 12)C line measurements for flares at five different heliocentric angles with calculations for different interacting-particle distributions. A downward isotropic distribution (or one with a small upward component) provides a good fit to the line measurements. An angular distribution derived for particles that undergo significant pitch angle scattering by MHD turbulence in coronal magnetic loops provides comparably good fits.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2002
- Accession Number
- ADA596969
Entities
People
- Gerald H. Share
- Juergen Kiener
- Nicolas De Sereville
- Ronald J. Murphy
Organizations
- United States Naval Research Laboratory