Speaker
Description
How elements beyond Fe are produced in stars continues to be an open question in nuclear astrophysics. Traditionally, two main pathways along the neutron-rich side of the chart of nuclides were shown to explain heavy element nucleosynthesis: the slow (s-) and rapid (r-) neutron capture processes. However, in recent astronomical observations, especially in Carbon-Enhanced Metal Poor (CEMP) stars, the abundance patterns of certain elements cannot be explained by these two processes alone. Hence, an additional, independent nucleosynthesis pathway is required to explain these observed abundances, being the intermediate (i-) neutron-capture process.
For nuclei that are involved along the i-process pathway, structural properties such as masses and $\beta$-decay half-lives are experimentally well constrained except for neutron-capture reaction rates, which are almost 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 constraints on the $^{87,88}$Kr(n,$\gamma$) $^{88,89}$Kr reactions will be discussed utilizing the $\beta$-Oslo method. This experiment utilized the CARIBU facility at Argonne National Laboratory using the indirect method of $\beta$-decays from $^{88,89}$Br into $^{88,89}$Kr. Subsequent $\gamma$-rays were identified the using the Summing NaI(Tl) detector, SuN, and the SuNTAN tape transport system. This presentation will feature the recently published results of the experimentally constrained cross section for $^{88,89}$Kr, both obtained by exploiting their statistical properties. The impact of these reactions on the final abundances of Rb and Sr will be discussed in this talk.