Diffuse emission of 26Al and 60Fe in the Galaxy

Abstract

Cosmic gamma-ray line signals are very weak, and the gamma-ray photons are absorbed by the atmosphere. The detection of Galactic radioactivity must be based on the gamma-ray detectors aboard balloons and spacecrafts. The first gamma-ray line observations were from OSO-3, OSO-7 in 1960's, which revealed the strong 2.223 MeV line from solar flares (Brandt, 1969). This line results from the formation of deuterium via the union of a neutron and proton; in a solar flare the neutrons appear as secondaries from interactions of high-energy