The reaction ${}^{58}\mathrm{Ni}{(}^{32}\mathrm{S},\alpha 2p)$ at $E_{\mathrm{lab}}=135\mathrm{}\mathrm{MeV}$ was used to populate high-spin states in ${}^{84}\mathrm{Zr}.$ The complete GAMMASPHERE and MICROBALL arrays were used to obtain clean γ-γ-γ line shapes to be analyzed by the Doppler shift attenuation method and to determine 27 lifetimes in the ground-state band and in two excited bands. Side-feeding times were also measured by comparing the line shapes gated with transitions above and below the state under study. The deduced electric quadrupole moments for the ground-state band are consistent with a very slow reduction with frequency with values ranging between 2.4(3) and $2.0\left(1\right)e\mathrm{b}.$ The negative-parity bands feature also an approximate constancy of quadrupole moment with values similar to those in the ground-state band. Cranking calculations agree with this behavior in both parity bands and suggest an interpretation of the upper states in the ground-state band as part of a very slowly terminating band. Shell-dependent cranked Nilsson calculations explain a fourth γ cascade as pertaining to a noncollective structure terminating at ${I=20\mathrm{}}^{+}.$

• Received 3 December 2002

DOI:https://doi.org/10.1103/PhysRevC.68.024303