Lifetimes of high-spin states in the pi i(13/2) band of Re-173

Lifetime measurements on the i(13/2) band built on the proton configuration 1/2(+)[660] in Re-173 have been carried out by the Doppler-broadened line shape method with the use of the GAMMASPHERE array in an early-implementation arrangement. Lifetimes of the stretched E2 transitions from states of spin 41/2(+)-69/2(+) in this band were measured, and the transition quadrupole moments calculated from these lifetimes are consistent (average Q(1)=8.1+/-0.5 eb) with a large and near-constant deformation (beta(2) approximate to 0.29) over the frequency range of <(h)over bar omega> 0.29-0.47 MeV. This result attests to the strong deformation-driving effect of the intruder pi i(13/2) orbital when it lies just above the Fermi surface. From thin-target measurements, it was possible to add three new levels to this band and to determine that the experimental aligned angular momenta gradually evolve over a large frequency range and level off with a total gain characteristic of alignment by i(13/2) neutrons. Calculations carried out for diabatic configurations give a satisfactory accounting of the alignment gain. However, because of the large interaction between crossing bands, a more meaningful description of the deformation pattern in this band was achieved through calculations of the spin-adiabatic type. Both calculations are discussed and compared with the experimental results.