Shape transition at high spin manifested in the<i>γ</i>-ray decay of the giant dipole resonance in hot Dy nuclei

Abstract

The statistical \ensuremath{\gamma}-ray decay of the giant dipole resonance built on highly excited states in $^{151\mathrm{\ensuremath{-}}156}\mathrm{Dy}$ 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.