N. Marchini, M. Rocchini, M. Zielińska, A. Nannini, D. T. Doherty, N. Gavrielov, Patricia E. Garrett, K. Hadyńska-Klęk, A. Goasduff, D. Testov, S. Bakes, D Bazzacco, G. Benzoni, Tom Berry, D. Brugnara, F. Camera, W. N. Catford, M. Chiari, F. Galtarossa, N. Gelli, A. Gottardo, A. Gozzelino, A. Illana, J. M. Keatings, D. Mengoni, L. Morrison, D. R. Napoli, M. Ottanelli, P. Ottanelli, G. Pasqualato, F Recchia, S. Riccetto, M. Scheck, M. Siciliano, J.J. Valiente Dobón, I. Zanon
Low-lying states of 94 Zr were investigated via low-energy multi-step Coulomb excitation. From the measured γ -ray yields, 16 reduced E2 transition probabilities between low-spin states were determined, together with the spectroscopic quadrupole moments of the 2 1 , 2 + states. Based on this information, for the first time in the Zr isotopic chain, the shapes of the 0 1 , 2 + states including their deformation softness were inferred in a model-independent way using the quadrupole sum rules approach. The ground state of 94 Zr possesses a rather diffuse shape associated with a spherical configuration, while the 0 2 + state is triaxial tending towards oblate and more strongly deformed. The observed features of shape coexistence in 94 Zr are consistent with both Monte-Carlo shell-model predictions and IBM-CM calculations, and provide model-independent constraints on the shape character assigned in the IBM-CM to the intruder configuration in 92–96 Zr.