Formation of the 0. 511-MeV line in solar flares

Technical Report · Thu Jan 01 04:00:00 EST 1976

OSTI ID:7134918

Crannell, C J; Joyce, G; Ramaty, R; Werntz, C

The gamma-ray line produced at 0.51-MeV was studied, and is shown to be the result of either free annihilation of positrons with electrons or the decay of positronium by 2-photon emission. Positron annihilation from the bound state of positronium may also proceed by 3-photon emission, and result in a continuum with energies up to 0.51- MeV. Accurate calculations of the rates of free annihilation and positronium formation in a solar-flare plasma are presented. Estimates of the positronium-formulation rates by charge exchange and the rates of dissociation and quenching are also considered. The temperature and density dependence of the ratio of 3-photon to 2-photon emission is obtained. It is shown that when the ratio of free electrons to neutral atoms in the plasma is approximately unity or greater, the Doppler width of the 0.51-MeV line is a function of the temperature of the annihilation region. For the small ion densities characteristic of the photosphere, the width is predominantly a function of the density. (auth)

• Research Organization: National Aeronautics and Space Administration, Greenbelt, Md. (USA). Goddard Space Flight Center
• OSTI ID: 7134918
• Report Number(s): N-76-18029; NASA-TM-X-71066; X-682-76-6
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANNIHILATION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BASIC INTERACTIONS
BOLTZMANN STATISTICS
CHARGE EXCHANGE
DECAY
DISSOCIATION
ELECTROMAGNETIC INTERACTIONS
ELECTRON-POSITRON INTERACTIONS
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
GAMMA SPECTRA
INTERACTIONS
KEV RANGE
KEV RANGE 100-1000
LEPTON-LEPTON INTERACTIONS
LEPTONS
LINE WIDTHS
PARTICLE INTERACTIONS
POSITRONIUM
POSITRONS
SOLAR ACTIVITY
SOLAR FLARES
SPECTRA
TEMPERATURE DEPENDENCE