Identification and quadrupole-moment measurement of a superdeformed band in 84Zr

High-spin states in 84Zr were studied using the early implementation phase of the Gammasphere array and the "Microball" charged-particle detector system. A cascade of nine γ rays with a dynamic moment of inertia which is characteristic of superdeformed rotational bands in the A=80 region has been identified and assigned to 84Zr. The measured transition quadrupole moment of the band corresponds to a prolate quadrupole deformation of β2=0.53 and confirms the superdeformed nature of this band. This is the first direct experimental confirmation of the existence of the predicted superdeformed shell gap at N44 particle number.