COSMIC-RAY MODELS FOR EARLY GALACTIC LITHIUM, BERYLLIUM, AND BORON PRODUCTION

To understand better the early Galactic production of Li, Be, and B by cosmic-ray spallation and fusion reactions, the dependence of these p roduction rates on cosmic-ray models and model parameters is examined. The sensitivity of elemental and isotopic production to the cosmic-ra y path length magnitude and energy dependence, source spectrum, spalla tion kinematics, and cross section uncertainties is studied. Changes i n these model features, particularly those features related to confine ment, are shown to alter the Be- and B-versus-Fe slopes from a naive q uadratic relation. The implications of our results for the diffuse gam ma-ray background are examined, and the role of chemical evolution and its relation to our results is noted. It is also noted that the unmea sured high-energy behavior of alpha + alpha fusion can lead to effects as large as a factor of 2 in the resultant yields. Future data should enable Population II Li, Be, and B abundances to constrain cosmic-ray models for the early Galaxy.