  Radioactive nuclei, especially those created in SN explosion, have long been
suggested to be important contributors of galactic positrons. In this paper we
describe the findings of three independent OSSE/SMM/TGRS studies of positron
annihilation radiation, demonstrating that the three studies are largely in
agreement as to the distribution of galactic annihilation radiation. We then
assess the predicted yields and distributions of SN-synthesized radionuclei,
determining that they are marginally compatible with the findings of the
annihilation radiation studies.
