Constraints on the 72Kr rp-process waiting point

Weakly-bound or proton-unbound nuclei near the rp-process waiting points 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 due to its relatively long $\beta$-decay half life and inhibited proton capture. The ${}^{72}$Kr waiting point, however, may be bypassed by sequential 2p-capture through ${}^{73}$Rb -- a reaction which is extremely sensitive to the ${}^{73}$Rb proton separation energy, $S_{\textrm{p}}$. While recent measurements of ${}^{65}$As and ${}^{69}$Br have reduced uncertainties in the reaction sequence, the ${}^{72}$Kr waiting point still remains unconstrained. 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 determine $S_{\textrm{p}}({}^{73}\textrm{Rb})$ directly for the first time. Results from our recent ${}^{73}$Rb decay experiment will be presented.