Rotational bands and noncollective structures in85Zr

Abstract

The structure of the transitional nucleus ${}^{85}\mathrm{Zr}$ has been investigated through spectroscopy and lifetime measurements. States up to spins of $\frac{45}{2}\ensuremath{\Elzxh}$ and $\frac{39}{2}\ensuremath{\Elzxh}$ in the positive and negative parity bands, respectively, have been established through $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence measurements. The results indicate that there is a competition between collective and noncollective modes of excitation. Two pronounced band crossings have been observed in the positive parity sequence, while none is evident in the negative parity states. The pattern of shape evolution in the positive and negative parity bands is markedly different. The results of the experiments qualitatively corroborate the predictions of total Routhian surface calculations.