High-spin structure of normal-deformed bands in Zr-84

The reaction Ni-58(S-32,alpha2p) at E-lab=135 MeV was used to populate high-spin states in Zr-84. The complete GAMMASPHERE and MICROBALL arrays were used to obtain clean gamma-gamma-gamma 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(1)e 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 gamma cascade as pertaining to a noncollective structure terminating at I=20(+).