Electromagnetic transitions from levels of ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ which belong to the rotational bands $K^{\pi }=3^{+},0^{+}$ ($T=0\mathrm{}$) and $1^{-}$ have been studied by the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(\alpha ,n\gamma ){}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ reaction. Lifetimes have been measured by the recoil distance method (RDM) and by the Doppler-shift attenuation method (DSAM). From a comparison of the results obtained by the two methods, the stopping powers for ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ in the stopping materials used have been deduced. The adopted lifetimes $\tau$ (ps) for the levels studied [$E_{\mathrm{ex}}$ (MeV), $J^{\pi }$] are the following: 14.7 ± 0.7 [0.891, $J^{\pi }=4^{+}$], 4.8 ± 0.3 [1.528, $J^{\pi }=5^{+}$], 0.077 ± 0.020 [3.708, ($J^{\pi }=6^{+}$)], 2.40 ± 0.35 [1.984, $J^{\pi }=3^{+}$], 21.2 ± 1.0 [2.211, $J^{\pi }=1^{-}$], 8.8 ± 0.9 [2.572, $J^{\pi }=2^{-}$], and 0.64 ± 0.16 [3.521, $J^{\pi }=3^{-}$]. New branches for the $\gamma$-ray decay of the 1.984- and 2.572-MeV levels have been observed. The negative parity of the levels at 2.572 and 3.521 MeV has been definitively established. The electro-magnetic properties, of some of these levels, have been compared with the isobaric spin selection rules for $N=Z$ nuclei, with the predictions of the unified model of Nilsson and with recent shell-model calculations.

• Received 15 May 1973

DOI:https://doi.org/10.1103/PhysRevC.8.2169