Accelerated and ambient He abundances from gamma-ray line measurements of flares

The gamma-ray lines from Be-7 and Li-7 produced when flare-accelerated He n uclei interact with ambient He have been found to be surprisingly intense f rom measurements made by moderate-resolution gamma-ray spectrometers on the Solar Maximum Mission (SMM) and Compton Gamma Ray Observatory (CGRO) satel lites. These high intensities suggest either accelerated alpha/proton ratio s greater than or similar to 0.5 and/or an He/H abundance greater than 0.1 in the subcoronal regions where the particles interact. We have studied add itional gamma-ray lines in 20 flares produced by interactions of alpha part icles on Fe-56 and other elements to resolve this ambiguity. These measurem ents indicate, on average, that the ambient He abundance is consistent with accepted photospheric values and that an enhanced concentration of He is p resent in flare-accelerated particles. Although there is evidence for the p resence of accelerated He-3, its concentration is only a fraction of accele rated He-4. These studies also revealed a new weak line in the spectra at s imilar to 1.32 MeV that is attributed to an excited state of Fe-55.