Statistical Hauser-Feshbach Model Description of (n,alpha) Reaction Cross Sections for the Weak s-Process

The (n,alpha) reaction contributes in many processes of energy generation and nucleosynthesis in stellar environment. Since experimental data are available for a limited number of nuclei and in restricted energy ranges, at present only theoretical studies can provide predictions for all astrophysically relevant (n,alpha) reaction cross sections. The purpose of this work is to study (n,alpha) reaction cross sections for a set of nuclei contributing in the weak s-process nucleosynthesis. Theory framework is based on the statistical Hauser-Feshbach model implemented in TALYS code with nuclear masses and level densities based on Skyrme energy density functional. In addition to the analysis of the properties of calculated (n,alpha) cross sections, the Maxwellian averaged cross sections are described and analyzed for the range of temperatures in stellar environment. Model calculations determined astrophysically relevant energy windows in which (n,alpha) reactions occur in stars. In order to reduce the uncertainties in modeling (n,alpha) reaction cross sections for the s-process, novel experimental studies are called for. Presented results on the effective energy windows for (n,alpha) reaction in weak s-process provide a guidance for the priority energy ranges in the future experimental studies.