Nucleosynthesis in neutron rich supernova ejecta

A nuclear reaction network of 903 different, strong and electromagnetic reactions, linking 107 chemical constituents is used to study the elements synthesized in the neutron rich material, ejected in supernova explosions. A large number of three body reactions virtually eliminates the usual bottle neck at theA=5 mass gap.For initially high temperatures and densities,T=10¹⁰K and =7×10⁸ gm/cm³, with expansion time scales of 10^–3–10^–2 sec, three differentn top ratios,n/p=4,n/p=3/2, andn/p1, are considered for the ejected matter. In all three cases, the material synthesized is preponderantly heavy. For then/p=4 model, the conditions at the charged particle freeze-out are ideal for the r-process. The onset of this rapid neutron capture phase is explicitly shown with a sequence of time lapse abundance plots.