The structure of $^{23}$Al and consequences on the depletion of $^{22}$Na from ONe novae

There is interest in the structure of $^{23}$Al due to the contribution of the $^{22}$Mg(p, $\gamma )^{23}$Al and $^{22}$Na(p, $\gamma )^{23}$Mg reactions in the depletion of $^{22}$Na from ONe novae. Using MARS we produced and separated pure $^{23}$Al samples with a 48 MeV/u $^{24}$Mg beam from the K500 cyclotron at Texas A{\&}M University. New $\beta $ and $\beta -\gamma $ coincidence measurements were made with a thin scintillator, an HPGe detector and a fast tape transport system. Addition of a BGO Compton shield improved very much the quality of the $\gamma $ spectra around the transitions from the IAS state at 7803 keV. From the measured $\beta $ singles and $\beta -\gamma $ coincidence decay spectra we obtained the $^{23}$Al $\beta $-decay scheme, branching ratios and absolute log\textit{ft} values for several transitions. We clearly determined that the $^{23}$Al ground state spin and parity is J$^{\pi }$=5/2$^{+}$ , not 1/2$^{+}$, and also found spectroscopic information for the states that are resonances in the $^{22}$Na(p, $\gamma )^{23}$Mg reaction. It follows that the larger capture rate implied by the now-rejected lower spin value for $^{23}$Al can not explain the missing 1275 keV cosmic $\gamma $ -ray from the decay of long-lived $^{22}$Na, the last step in the hot NeNa cycle.