Astrophysical production rates for Li, Be, and B isotopes from energetic H(1) and He(4) reactions with HeCNO nuclei

Calculations for Li, Be, and B nucleosynthesis in reactions of energetic ¹H and ⁴He nuclei with ⁴He, ¹²,¹³C, ¹⁴N, and ¹⁶O nuclei have been performed. The calculations employed a recent compilation of cross section systematics for these reactions. Specific models examined include galactic cosmic-ray interactions with the interstellar medium, synthesis in flares, and formation in shock waves. The GCR + ISM calculations are able to account for the absolute abundances of ⁶Li, ⁹Be, ¹⁰B, and ¹¹B satisfactorily, but require a low-energy component of spectral form E-γ to account for the ¹¹B/¹⁰B isotopic ratio, where γ = 5-7. In these calculations ⁷Li is underproduced by an order of magnitude. The required ⁷Li is most probably provided by the big bang, an assumption that is consistent with an open universe. Synthesis solely in a flare mechanism cannot reproduce the observed relative abundances. The shock wave mechanism can account for the relative abundances, but only in a very narrow energy window near E/A = 10 MeV.