Octupole vibration in superdeformed 15266Dy86

Nine transitions of dipole character have been identified linking an excited superdeformed (SD) band in 1 5 2 Dy to the yrast SD band. As a result, the excitation energy of the lowest level in the excited SD band has beenmeasured to be 14 238 keV. This corresponds to a 1.3 MeVexcitation above the SD ground state. The levels in this band have tentatively been determined to be of negative parity and odd spin. The measured properties are consistent with an interpretation in terms of a rotational band built on a collective octupole vibration.