Neutrino induced light element synthesis

As the core of a massive star collapses to form a neutron star, the flux of neutrinos in the overlying shells of heavy elements becomes so great that, despite the small cross section, substantial nuclear transmutation is induced. Neutrinos, especially the higher energy μ- and τ-neutrinos, excite heavy elements and even helium to particle unbound levels. The evaporation of a single neutron or proton, and the back reaction of these nucleons on other species present, significantly alters the outcome of traditional nucleosynthesis calculations leading to a new process: ν-nucleosynthesis. The process was first studied by Domogatsky et al. and Woosley. Recent work by Epstein, Colgate, and Haxton and Woosley and Haxton suggested that a large number of elements could owe their existence in nature to ν-induced reactions in supernovae. A parametrized study of this process including shock wave propagation was carried out by Woosley et al. for selected zones of a 20 Mcircle-dot star. Here we give preliminary results for a 25 Mcircle-dot star, including all ν-reactions in all stellar zones