Understanding the thermal structure of the outer crust of accreting neutron stars is important for interpreting astronomical x-ray observations. Ground-state to ground-state $\beta$-decay transitions of neutron-rich nuclei comprising the crust enable Urca neutrino cooling processes that affect this thermal structure. Here we constrain the ground-state to ground-state transition strengths for the decays of ${}^{57}\mathrm{Sc}, {}^{57}\mathrm{Ti}$, and ${}^{59}\mathrm{Ti}$ based on experimental data. The data were obtained by combining total absorption $\gamma$-spectroscopy data from the SuN detection system with $\beta$-delayed neutron emission data from the NERO detection system at Michigan State University's National Superconducting Cyclotron Laboratory. We find $logft=5.8_{-0.2}^{+0.3}$ and $logft=5.{34}_{-0.24}^{+0.08}$ for the decays of ${}^{57}\mathrm{Ti}$ and ${}^{59}\mathrm{Ti}$, respectively, and find no evidence for ground-state feeding in the decay of ${}^{57}\mathrm{Sc}$. The results indicate weaker transitions than predicted by theory and indicated by previous measurements, resulting in reduced efficiency of neutrino cooling in accreted neutron star crusts in systems that exhibit x-ray superbursts.

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• Beta decay
• Electromagnetic transitions
• Neutron star cooling
• Nuclear astrophysics
• Neutron star crust
• 39 ≤ A ≤ 58
• 59 ≤ A ≤ 89