Transition quadrupole moments of highspin states in ^{172}Os
Abstract
Lifetimes of states in ^{172}Os have been measured by the Dopplershift recoildistance method. These states were populated by the reaction ^{144}Nd( ^{32}S, 4n) ^{172}Os at a bombarding energy of 162 MeV from the HHIRF tandem accelerator at ORNL. The data were collected in the γγcoincidence mode in order to reduce the complexities of the γray spectra and to avoid some of the problems associated with side feeding to excited states. The experimental transition quadrupole moments, Q_{t}, do not cluster about a constant value as a function of rotational frequency up through h̵ω = 0.27 MeV as predicted by cranked HartreeFockBogoliubov (HFB) calculations around N = 96 for the yrast band. A striking feature in the experimental data for the yrast band is an abrupt increase of the Q_{t} values for the 6 ^{+} and 8 ^{+} states where the first anomaly in the behavior of the moment of inertia occurs. A recent proposal of bandmixing between the yrast band and a quasiβ band to account for this anomaly in the moment of inertia also seems to provide a logical interpretation of the Q_{t} values at low rotational frequencies. The large collectivity inferred for the quasiβ band from our Q_{t} values for the 6 ^{+} and 8 ^{+} states is an indirect, but plausible, argument that the quasiβ band corresponds to the nonyrast band in the bandmixing model. The E1 transition probabilities for decay of states in the ( π, α) = (, 1) band to states in the groundstate band range between 1.4 × 10 ^{5} to 3.1 × 10 ^{4} W.u. The B(E1, I → I + 1) is an order of magnitude larger than the B(E1, I → I  1). The origin of these effects can probably be understood in terms of a predominant admixture of the Corioliscoupled octupole vibrationalstate wave function in the (, 1) band of ^{172}Os at low spin.
 Publication:

Nuclear Physics A
 Pub Date:
 February 1995
 DOI:
 10.1016/03759474(95)00132K
 Bibcode:
 1995NuPhA.591..145V