Network calculations for r-process nucleosynthesis

Abstract

The r-process is known to be responsible for the synthesis of about half of the elements heavier than iron, nevertheless its astrophysical site has not yet been clearly ascertained, but observations indicate that at least two possible sites should contribute to the solar system abundance of r-process elements. The r-process being responsible for the production of elements heavier than Z = 56 operates rather robustly always resulting in a similar relative abundance pattern. From the nuclear-physics point of view the r-process requires the knowledge of a large number of reaction rates involving exotic nuclei that are not accessible by experiment and data have to be provided by theoretical predictions. We have developed for the first time a complete database of reaction rates that in addition to neutron-capture rates and β-decay half-lives includes the dominant reactions that can induce fission (neutron-capture, β-decay and spontaneous fission) and the corresponding fission yields. In addition, we have implemented these reaction rates in a fully implicit reaction network. The influence of the nuclear physics input constituted in the reaction rates based on the two mass models FRDM and ETFSI and on the astrophysical conditions simulating a cold or hot environment are examined.