Speaker
Description
Charged-particle reactions play a critical role in nucleosynthesis in slightly neutron-rich, neutrino-driven winds from core-collapse supernovae, where the reaction flow proceeds near stability and β-decays are too slow to efficiently drive matter to heavier nuclei. In this regime, (α,n) reactions are key to the production of elements in the Z ≈ 38–47 region, which are commonly observed in metal-poor stars. However, the reaction rates used in astrophysical models are largely derived from Hauser–Feshbach calculations and suffer from significant uncertainties due to poorly constrained nuclear inputs away from stability. Sensitivity studies have identified the $^{86}$Kr(α,n)$^{89}$Sr reaction as one of the most influential contributors to these uncertainties across a wide range of wind conditions.
To address this need, a direct measurement of the $^{86}$Kr(α,n)$^{89}$Sr reaction has been performed in inverse kinematics using the SECAR (SEparator for CApture Reactions) recoil separator at FRIB. While originally designed for radiative capture studies, the scientific reach of SECAR has been extended to include measurements of (α,n) and (α,2n) reactions. In this talk, I will present preliminary results for both channels, including the first experimental constraints on the $^{86}$Kr(α,2n) reaction in this system, and discuss their astrophysical implications. These results demonstrate the capability of SECAR for precision studies of charged-particle reactions, opening the path toward future direct measurements on short-lived nuclei relevant to heavy-element nucleosynthesis.