Proton decay of ${}^{73}$Rb

Properties of nuclei beyond the proton drip-line are important for mass models, nuclear structure, and astrophysics. Weakly-bound or proton-unbound nuclei near the rp-process waiting points, such as the unbound $T_{z}=-\frac{1}{2}$ nucleus ${}^{73}$Rb, play a critical role in constraining calculations and observations of type I x-ray bursts. For instance, the rp process is greatly slowed near ${}^{72}$Kr ($N=Z$) due to its relatively long $\beta$-decay half life and inhibited proton capture. This waiting point, however, may be bypassed by sequential 2p-capture through ${}^{73}$Rb ~\textemdash~ a reaction which is sensitive to the ${}^{73}$Rb proton separation energy, $S_{\textrm{p}}$. Using invariant-mass spectroscopy, we have performed an experiment at NSCL to measure the decay of ${}^{73}$Rb$\rightarrow$p+${}^{72}$Kr in an attempt to directly determine $S_{\textrm{p}}({}^{73}\textrm{Rb})$. Analysis of reconstructed proton-emission spectra and decay signatures will be discussed.