High-spin multi-particle and collective structure in 178W.

The high spin structure of the nucleus 178W has been studied, at the Australian National University, with the 170Er(13C,5n) reaction at 80 MeV. Many previously unidentified rotational bands are seen based on high-K, 2, 4, 6 and 8-quasiparticle structures, some of which are isomeric. This is the first identification of rotational bands based on 8-quasiparticle states. The excitation energies of the multiquasiparticle bandheads are compared with BCS calculations, including residual interactions. The bands show substantial increases in moments-of-inertia with increasing quasiparticle number. These are examined in terms of pairing blocking. The effect of blocked pairing is also taken into account in the calculation of g-factors, which supports the configuration assignments. The Kpi = 25+, eight-quasiparticle band forms the yrast line from its bandhead upwards. This bandhead is a 220 ns isomer whose decay is strongly hindered, compared to the decay of the four- and six-quasiparticle structures