Inelastic excitation of new high-spin yrast isomers in 180Ta

For the first time, six-quasiparticle isomers have been observed in the meta-stable nucleus Ta-180(73)107. Two new high-spin isomers were populated following deep-inelastic reactions with a pulsed U-238(92) beam incident on a thick Hf-180(72) target. Out-of-beam gamma -ray events were collected using the Gammasphere germanium detector array. In addition to the known four-quasiparticle isomers, yrast K-pi = (22(-)) and K greater than or equal to 23 six-quasiparticle isomers have been observed with microsecond half-lives. These are the highest-spin isomers observed using the technique of deep-inelastic excitation. The assignments are compared to predictions made by BCS and Lipkin-Nogami multiquasiparticle calculations.