Observation of Rigid Nuclear Rotation

Abstract

States in $^{84}\mathrm{Zr}$ with angular momenta up to $34\ensuremath{\hbar}$ and rotational frequency 1.3 MeV have been studied with the techniques of discrete-line gamma-ray spectroscopy. The measurements probe the region beyond a second upbend. In this region the results are consistent with the nucleus having undergone a transition to an axially symmetric shape with $\ensuremath{\beta}=0.43\ifmmode\pm\else\textpm\fi{}0.06$ and $\ensuremath{\gamma}=3\ifmmode^\circ\else\textdegree\fi{}\ifmmode\pm\else\textpm\fi{}6\ifmmode^\circ\else\textdegree\fi{}$ which rotates with the rigidbody moment of inertia.