Nuclear processes in solar flares

Interaction models for the production of gamma rays in energetic particle reactions are reviewed, and new calculations of the production rates are presented. Neutron and 2.223 MeV photon production is considered along with positron and 0.511 MeV photon production, and prompt de-excitation line production. The implications of gamma-ray observations are explored, taking into account the interaction model, energetic particle spectrum and energy content, time dependences, the photospheric He-3 abundance, and the beaming of the energetic particles. It is pointed out that the solar gamma-ray line observations can provide information on the timing of the nucleonic component in flares, and on the energy spectrum, number, and energy content of these particles.