Kr reaction in the Astrophysical i-process using the β-Oslo method.

How elements are produced in stars remains to be one of the main questions in nuclear astrophysics. The traditional nuclear landscape shows that elements are created through either the slow (s) and rapid (r) processes. In recent astronomical observations, ``strange” abundance patterns are seen in Carbon-Enhanced Metal Poor (CEMP) stars, which cannot be explained by these two processes alone. This indicates that an additional nucleosynthesis process is required to explain these abundances, the astrophysical intermediate (i) neutron-capture process.

The i-process occurs 2-8 mass units away from the valley of stability, where structural properties of the nuclei involved are experimentally well constrained, however the neutron-capture reaction rates are entirely provided by theory.

Recent sensitivity studies have shown that the Rb/Sr abundances are strongly affected following the neutron-capture reactions on Kr isotopes. In this talk, the first experimental constraint of the ^87,89Kr(n,γ)^88,90Kr reactions will be discussed utilizing the β-Oslo method.

This experiment took place at the CARIBU facility at Argonne National Laboratory using the indirect method of β-decays from the ^88,90Br nuclei into ^88,90Kr. Subsequent γ-rays were identified using the Summing NaI detector, SuN, and the SuNTAN tape transport system.

By exploiting the statistical properties of ^88,90Kr, experimentally constrained cross sections are extracted and their impact on the astrophysical i-process will be discussed.