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Abstract Nuclear beta decays provide an excellent probe of fundamental symmetries due to their mediation by the weak interaction. In particular, precise measurements of these decays provide constraints on the unitarity of the Cabbibo-Kobayashi-Maskawa (CKM) quark-mixing matrix. While superallowed pure Fermi decays currently set the most precise limits, the alternative suite of superallowed mixed mirror decays has been ill-studied. These nuclei can provide an important consistency check of calculation and measurement methods employed for the pure Fermi decays, more critically needed now in the wake of a 2.4σ deviation from unitarity of the CKM matrix. In order to remedy the gap in data for mirror decays, the Superallowed Transition Beta-Neutrino Decay Ion Coincidence Trap (St. Benedict) facility is being commissioned at the University of Notre Dame's Nuclear Science Laboratory (NSL). In this paper, we present first results of the commissioning of the St. Benedict facility on-line at the TwinSol radioactive beam facility. The results of initial commissioning experiments involving the St. Benedict gas catcher, RF carpet, RFQ ion guide and RFQ cooler-buncher will be presented. 

Nuclear reactions play a crucial role in determining the nucleosynthesis that occurs in astrophysical events. The rates of many reactions that significantly impact certain nucleosynthesis processes can not be currently measured via direct means. These reactions must be constrained in another manner, such as determining the level energies and other structure properties of the compound nuclei. In order to measure level energies of nuclei relevant to nuclear astrophysics, the Enge split-pole spectrograph has been installed and commissioned at the University of Notre Dame’s Nuclear Science Laboratory. The first scientific measurement has also been performed. Structure properties of⁵⁸Cu were measured via the reaction⁵⁸Ni(³He,t)⁵⁸Cu to provide the first experimental constraint of the⁵⁷Ni(p,γ)⁵⁸Cu reaction rate, which impacts the production of of⁴⁴Ti,⁵⁷Fe, and⁵⁹Ni in core-collapse supernovae. Preliminary analysis of this measurement confirms the level energies of states in⁵⁸Cu that could lead to significant resonances in the⁵⁷Ni(p,γ)⁵⁸Cu reaction rate, while suggesting the presence of additional states that have not been previously observed but could also lead to significant resonances.