Recoil distance lifetime measurements of states in the oblate dipole bands ofPb197,198

Lifetimes of states in four of the oblate dipole bands in ${}_{}{}^{197,198}{}_{}{}^{}\mathrm{Pb}$ have been measured with the recoil distance technique. Using all the available data on lifetimes and branching ratios, and assuming pure magnetic dipole transitions, we deduce transition probabilities. The results are consistent with weakly oblate collective structures involving high-K proton configurations coupled to rotationally aligned neutrons. Comparsions are made to the theoretical estimates of the Dönau and Frauendorf semi-classical model and the tilted axis cranking (TAC) model.