HR: 0830h
AN: SP21A-09    [Abstracts]
TI: The Physics of Positron Annihilation in the Solar Atmosphere
AU: * Murphy, R J
EM: murphy@ssd5.nrl.navy.mil
AF: Naval Research Laboratory, Code 7650 4555 Overlook Ave, Washington, DC 20375 United States
AU: Skibo, J G
EM: skibo@iols.com
AF: Naval Research Laboratory (affiliation when work was performed), Code 7650 4555 Overlook Ave, Washington, DC 20375 United States
AU: Share, G H
EM: gerald.share@nrl.navy.mil
AF: Naval Research Laboratory, Code 7650 4555 Overlook Ave, Washington, DC 20375 United States
AU: Kozlovsky, B
EM: benz@wise1.tau.ac.il
AF: School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, CA 94720 Israel
AB: We have developed an algorithm that calculates the 511-keV annihilation line spectrum and relative strength of the 3-gamma continuum for a wide range of physical environments from the flaring solar atmosphere to the interstellar medium. We present evaluated cross sections for each of the processes relevant to the positrons and their annihilation based on the most recent measurements and calculation. The calculation begins with a Monte Carlo code that follows positrons as they slow down to thermal energies or form positronium in flight. We then calculate the thermally-averaged annihilation and positronium production rates, and the positronium quenching rates. We apply the results to four specific environments (fully ionized, neutral, partially ionized and a non-LTE model of the quiet solar atmosphere), and calculate the relative strengths of each process and the combined total annihilation line spectrum. The results are compared with data obtained recently from the high spectral-resolution detectors of RHESSI. We find that positron annihilation in solar flares can occur in a wide variety of environments that can be quite different from currently-accepted solar atmospheres.
UR: http://heseweb.nrl.navy.mil/gamma/solar/highe.html
DE: 7507 Chromosphere
DE: 7514 Energetic particles (2114)
DE: 7519 Flares
DE: 7554 X rays, gamma rays, and neutrinos
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly