Preliminary results for constraining i-process reaction rates

The majority of elements heavier than iron are produced via neutron capture processes, primarily the s process and the r process. However, certain astrophysical observations, such as Sakurai’s object and several CEMP stars that show enhancement of s- and r-elements, cannot be described by either process or a combination of the two. The intermediate i process was proposed as a neutron capture process that proceeds at neutron densities between those of the s and r processes, in a region several neutrons away from stability. Models to determine the final abundance pattern of astrophysical environments depend on nuclear physics input, including β-decay rates, nuclear masses, and neutron capture rates. Denissenkov et al. performed a sensitivity study on the neutron capture rates of 52 unstable isotopes and determined eight reactions that had the largest impact on the final abundance pattern of an i process model. Measurements of the neutron capture rates on ^85-86Br, ^87-89Kr, ⁸⁹Rb, and ^89,92Sr, would significantly reduce the uncertainties. The preliminary results of an experiment performed at Argonne National Lab using the SuN detector, its associated tape station (SuNTAN), and beams from the CARIBU facility will be presented for the indirect study of ^87-89Kr(n,γ)^88-90Kr.