Directionality of Flare-Accelerated Alpha Particles at the Sun
Abstract
RHESSI has observed the 7Be and 7Li -ray lines from fusion of accelerated alpha particles with ambient helium produced during the 2002 July 23 solar are that erupted at a heliocentric angle of 73 deg. This is the first observation of the lines with a germanium spectrometer. We have fit the measured lines with calculated shapes for different energy and angular distributions for the interacting alpha particles. A particle distribution from saturated pitch-angle scattering in the corona provides the best fit, but isotropic, downward-isotropic, or fan-beam distributions also provide acceptable fits. We can rule out a downward-beamed distribution with 99.99% confidence. RHESSI measurements of other Doppler-shifted nuclear de--excitation lines are consistent with a forward isotropic distribution of interacting particles in a magnetic loop tilted by ~40 deg from the normal to the solar surface toward Earth. Such a distribution is also consistent with the alpha-4He line shape with ~15% confidence.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2003
- Accession Number
- ADA605061
Entities
People
- Brian R. Dennis
- David M Smith
- Gerald H. Share
- Richard A. Schwartz
- Robert P. Lin
- Ronald J. Murphy
Organizations
- National Aeronautics and Space Administration