5.534 MeV level inNa23

The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{12}{}_{}{}^{}\mathrm{C}, p\gamma ){}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ reaction has been used at an incident energy of 28.2 MeV to populate the 5.534 MeV level in ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$. A particle $\gamma$-ray linear polarization measurement carried out simultaneously with a particle $\gamma$-ray angular correlation measurement for the 3.457 MeV transition between the 5.534 MeV and 2.077 MeV (${\frac{7}{2}}^{+}$) levels allows an unambiguous $J^{\pi }={\frac{11}{2}}^{+}$ assignment to be made to the 5.534 MeV level. The multipole mixing ratio of the 2.829 MeV transition between the 5.534 MeV and 2.705 MeV (${\frac{9}{2}}^{+}$) levels has been obtained and confirms previous measurements, as does the measured branching ratio for the two observed decay modes from the 5.534 MeV level.