Electromagnetic properties of excited states of ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ below 4.6-MeV excitation energy have been studied using the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}({}_{}{}^3{}_{}{}^{}\mathrm{He}, \alpha \gamma ){}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ and ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(\alpha , n\gamma ){}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ reactions. Investigation of the decay scheme of the 4069-keV level using the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}({}_{}{}^3{}_{}{}^{}\mathrm{He}, \alpha \gamma ){}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ reaction shows a (10 ± 3)% branch to the 1528-keV level, compared to a value of 21% reported previously. The existence of weak $\gamma$-ray transitions from the 1983-, 2211-, and 2572-keV levels has been confirmed from $\gamma$-ray spectra obtained above and below threshold for population of these levels via the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(\alpha , n){}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ reaction. A long standing controversy regarding the spin of the 1983-keV level has been resolved by $\gamma$-ray angular distribution measurements close to threshold for the population of the 1983-keV level via the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(\alpha , n){}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ reaction; the results show that $J^{\pi }\mathrm{}\left(1983\right)=3^{+}$. Neutron-$\gamma$ correlation studies of the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(\alpha , n\gamma ){}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ reaction, taken in conjunction with previous data, impose limitations on spins and parities of several levels and on mixing ratios of associated $\gamma$-ray transitions. The spin-parity values are as follows, relatively unlikely assignments being bracketed: $J^{\pi }\mathrm{}\left(3708\right)=6^{+}\left(4^{\pm }\right)$; $J^{\pi }\mathrm{}\left(4069\right)=4^{+}$; $J^{\pi }\mathrm{}\left(4466\right)=1^{-}, 2^{\pm }, 3^{-}, or 4^{-}$; $J^{\pi }\mathrm{}\left(4522\right)=7^{+}, 5^{\pm }(4^{-}, 6^{+})$.

NUCLEAR REACTIONS ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}({}_{}{}^3{}_{}{}^{}\mathrm{He}, \alpha \gamma )$, $E=8.46\mathrm{}$ MeV; measured $\sigma (E_{\alpha }, E_{\gamma })$. ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ level deduced $\gamma$ branching. ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(\alpha , n\gamma )$, $E=4.7-6.1\mathrm{}$ MeV; measured $\sigma (E, E_{\gamma })$. ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ levels deduced $\gamma$ branching. ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(\alpha , n\gamma )$, $E=5.0-5.2\mathrm{}$ MeV; measured $\sigma (E_{\gamma }, \theta )$. ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ level deduced $J$, $\pi$, $\delta$. ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(\alpha , n\gamma )$, $E=11.2\mathrm{}$ MeV; measured $\sigma (E_n, E_{\gamma }, {\theta }_{n\gamma })$. ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ deduced levels; ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ levels deduced $J$, $\pi$, $\delta$, $\tau$.

• Received 15 October 1974

DOI:https://doi.org/10.1103/PhysRevC.11.742