Experimentally Constrained Neutron-Capture Cross Sections for the Astrophysical i-Process

One of the biggest open questions in Nuclear Astrophysics regards the origin of the elements in the universe. It is well known that more than half of the heavy elements are synthesized by neutron-capture processes (s, i, r), but to this day, limited nuclear data exist for neutron-capture cross sections. The astrophysical i process occurs in stellar environments such as carbon-enhanced metal poor stars (CEMP) or Rapidly Accreting White Dwarf stars (RAWDs) for nuclei approximately 2-8 neutrons from stability in regions currently accessible by radioactive beam facilities. The i process involves short-lived isotopes for which capture cross sections cannot be measured via direct techniques. Instead reaction rates in these regions rely on calculations that have uncertainties up to a few orders of magnitude. Over the last few years, several indirect neutron-capture techniques have been developed to allow us to access neutron-capture cross sections for unstable nuclei relevant to the i process and beyond. In this presentation, I will discuss indirect neutron-capture constraints for the Sr and Ba isotopes using techniques such as the β-Oslo method and the Surrogate Reaction method and their implications for i-process nucleosynthesis.