Positronium interaction with low-energy radiation

The cross sections of elastic photon scattering, Compton scattering and photodisintegration for positronium are calculated for incident photon energies below 3 keV. The relation between positronium and hydrogen matrix elements for these processes is established and we compare our positronium cross section calculations with the corresponding hydrogenic data. We present the model for the positronium triplet state depletion before annihilation, when the positronium atoms are exposed to black-body radiation, and the breakup process occurs. We discuss the relevance of our breakup calculation for the positron annihilation process in solar flares.