From an analysis of the experimental data, we assign $I^{\pi }=3^{-}$ (and $I=4^{+}$) levels in even ${}_{86}{}^{}{}_{}{}^{}\mathrm{Rn}$ nuclei. These levels, together with known levels with $I^{\pi }=1^{-}$ in ${}_{86}{}^{}{}_{}{}^{}\mathrm{Rn}$ and negative parity levels $K^{\pi }=0^{-}$; $I=1^{-},3^{-},\mathrm{and}{5}^{-}$ in ${}_{88}{}^{}{}_{}{}^{}\mathrm{Rn}$, ${}_{90}{}^{}{}_{}{}^{}\mathrm{Th}$, and ${}_{92}{}^{}{}_{}{}^{}\mathrm{U}$, demonstrate features of strong Coriolis coupling. The existence of strong Coriolis coupling effects is typical only for rotational bands based on one-phonon octupole vibrational states which include particles with large$j$ ($j_{\frac{15}{2}}$, $i_{\frac{13}{2}}$, etc.), but not for bands based on states $K^{\pi }=0^{-}$; $I=1^{-}$ with stable octupole deformation.

NUCLEAR STRUCTURE $A\gtrsim 218$ Rn, Ra, Th; analyzed levels, $\alpha$, $\beta$, $\gamma$ hindrances for octupole bands; deduced $I^{\pi }$ in ${}_{}{}^{218,220,222}{}_{}{}^{}\mathrm{Rn}$.

• Received 27 October 1980

DOI:https://doi.org/10.1103/PhysRevC.24.1336