Population of Triaxial Rotor Levels in ${}_{}{}^{182}{}_{}{}^{}\mathrm{Os}$

A $K$-isomeric state in ${}_{}{}^{182}{}_{}{}^{}\mathrm{Os}$ with spin $I=(20\mathrm{}\pm 2)\hslash$ and half-life equal to 100 ns is found to decay in flagrant violation of the usual $K$-selection rules. The observations—still preliminary—are on the other hand readily understood if it is assumed that the yrast configuration of ${}_{}{}^{182}{}_{}{}^{}\mathrm{Os}$ becomes triaxial above the backbend, and that the decay proceeds via the numerous collective levels of the triaxial rotor.