COSMIC-RAY NUCLEOSYNTHESIS IN THE EARLY GALAXY

Cosmic ray spallation/fusion reactions may yield astrophysically interesting amounts of lithium, beryllium and boron during the early evolution of the Galaxy. In particular, since alpha,alpha fusion reactions can produce Li-6 and Li-7 whereas Be and B require CNO nuclei as spallation targets, the Pop II ratios of Li to Be and/or B are vastly different from their Pop I counterparts. Current data on Pop II Be do not exclude the possibility that significant amounts of lithium have been produced via this mechanism. The observed increase in the Pop II abundance of beryllium with increasing metallicity points to synthesis during the early Galaxy. The boron to beryllium ratio is relatively insensitive to model-dependent, evolutionary uncertainties and could provide a signature for cosmic ray nucleosynthesis during the early Galaxy.