The statistical γ-ray decay of the giant dipole resonance built on highly excited states in ${}_{}{}^{151\mathrm{-}156}{}_{}{}^{}\mathrm{Dy}$ has been used as a probe for studying the evolution of the nuclear shape with increasing angular momentum. The observed shift of the giant dipole resonance strength to lower energy suggests a change of the nuclear deformation from prolate to oblate with increasing spin.

• Received 14 June 1989

DOI:https://doi.org/10.1103/PhysRevC.40.R2454