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Steady flow approximations to the heliumR-process
Authors:A G W Cameron  J J Cowan  H V Klapdor  J Metzinger  T Oda  J W Truran
Institution:1. Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
2. Department of Physics and Astronomy, University of Oklahama, Norman, USA
3. Max-Planck-Institut für Kernphysik, Heidelberg, F.R.G.
4. Department of Astronomy, University of Illinois, Urbana, USA
Abstract:R-process yields for a helium layer have been calculated within a network of 6033 heavy nuclei using a steady flow approximation. The calculation of the neutron capture cross sections has been improved. The beta decay rates computed by Klapdor and his colleagues have been used in the calculation. We find that ther-process yield peaks near mass numbers 80 and 130 require a neutron number density of approximately 1020 cm?3 and a freezing time comparable to or less than 0.1 s. The peak near mass number 195 requires a neutron number density of about 1021 cm?3 and a freezing time comparable to or less than about 0.01 s. The individual yield features of the steady flowr-process depend entirely upon the neutron capture cross sections of the nuclei along the flow path and the beta decay rates, which can shift the flow path and thereby introduce inappropriate capture cross sections into the determination of the yields.
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