High-Resolution Observation of the Solar Positron-Electron Annihilation Line
Abstract
The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) has observed the positron-electron annihilation line at 511 keV produced during the 2002 July 23 solar flare. The shape of the line is consistent with annihilation in two vastly different solar environments. It can be produced by formation of positronium by charge exchange in flight with hydrogen in a quiet solar atmosphere at a temperature of 6000 K. However, the measured upper limit to the 3g/2g ratio (ratio of annihilation photons in the positronium continuum to the number in the line) is only marginally consistent with what is calculated for this environment. The annihilation line can also be fitted by a thermal Gaussian having a width of 8.1 +/- 1.1 keV (FWHM), indicating temperatures of (4 7) x 10(expn 5) K. The measured 3g/2g ratio does not constrain the density when the annihilation takes place in such an ionized medium, although the density must be high enough to slow down the positrons. This would require the formation of a substantial mass of atmosphere at transition-region temperatures during the flare.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2003
- Accession Number
- ADA596986
Entities
People
- Albert Y. Shih
- Benzion Kozlovsky
- Brian R. Dennis
- David M Smith
- Gerald H. Share
- Hugh S. Hudson
- Jeffrey G. Skibo
- Richard A. Schwartz
- Robert P. Lin
- Ronald J. Murphy
Organizations
- United States Naval Research Laboratory