SEARCH FOR NUCLEOSYNTHETIC AND COSMIC-RAY INDUCED GAMMA-RAY LINES FROM THE GALACTIC PLANE

We have combined all OSSE spectra of the central radian of the Galaxy obtained through the end of 1994. These data have been searched for ev idence of diffuse emission of nucleosynthetic gamma-ray lines (Na-22, 1.275 MeV: Fe-60, 1.17 and 1.33 MeV) and cosmic-ray induced gamma-ray lines (de-excitation of C-12, 4.44 MeV, and of O-16*, 6.13 MeV). We h ave looked in detail at possible systematic errors in the line measure ments. Our preliminary results show no evidence for the presence of ei ther broad or narrow cosmic-ray induced lines, nor for emission from N a-22, down to 3 sigma upper limits similar or equal to 2 10(-4)gamma/( cm(2)-sec-rad). We find weak evidence (approximate to 2 sigma) of Fe-6 0 line emission from positive Galactic longitudes in the central radia n.