${}^{69}$Kr $\beta$-delayed proton emission

Proton-rich nuclei beyond the $N=Z$ line play a key role in our understanding of astrophysics, weak-interaction physics, and nuclear structure tests. In particular, the decay of ${}^{69}$Kr populates states in the proton-unbound nucleus ${}^{69}$Br. While recent measurements of ${}^{65}$As and ${}^{69}$Br have constrained key $rp$- process waiting points, spectroscopic and structural information remains elusive. An experiment was conducted at GANIL which utilized implant-$\beta$-$p$ and $\beta$-$\gamma$ correlations to study physics related to the $\beta$ decays of ${}^{69,70,71}$Kr. Isotopes were implanted into a Si-DSSD, also used to detect decay protons, located at the end of the LISE spectrometer. Coincident $\gamma$-rays were measured in surrounding HpGe EXOGAM clovers. We identified $212$ ${}^{69}$Kr implantation-decay events and observed a dominant superallowed $\beta$-decay branch ($T_{1/2}=27(3)$~ms) to the isobaric analog state which decays via $2.97(5)$~MeV protons to the first excited state in ${}^{68}$Se. This decay path strongly constrains the spin and mass of ${}^{69}$Kr.