Intrinsic states and collective structures in 180Ta

Excited states in Ta-180 have been identified using the Yb-176(B-11,alpha 3n)Ta-180 and Yb-176(Li-7,3n)Ta-180 reactions and associated time-correlated gamma-ray spectroscopy, including particle-gamma coincidences for channel selection. As well as identifying the rotational band based on the 9(-) two-quasiparticle state at 75 keV, at least eight other low-lying two-quasiparticle states and associated rotational bands have been established. Lifetimes in the few nanosecond region were isolated using gamma-gamma-time techniques. Most of the observed two-quasiparticle states and some of the band members can be identified with states known from particle transfer studies. The properties of the observed Omega(n)+/-Omega(p) partners of 1(+) and 8(+) bands from the nu 9/2(+)[624]circle times pi 7/2(+)[404] configuration and the 0(-) and 9(-) pair from the nu 9/2(+)[624]circle times pi 9/2(-)[514] configuration are discussed. High-K structures identified include the band based on the four-quasiparticle 45 mu s, 15(-) isomer, a 32 ns, four-quasiparticle 18((+)) isomer, and a six-quasiparticle 19((-)) intrinsic state and its band. Configuration assignments are aided by analysis of the in-band decay properties, which confirm, for example, a predominantly nu pi(3) configuration for the 15- isomer. The results are compared with multiquasiparticle calculations. A number of yrast high-K six- and eight-quasiparticle states which could be accessible in future studies are predicted.