Multi-quasiparticle isomers and rotational bands in ¹⁷⁸W

The high spin structure of the nucleus ¹⁷⁸W has been studied following the ¹⁷⁰Er(¹³C,5n) reaction. Many previously unidentified rotational bands are seen based on high-K, 2-, 4-, 6-and 8-quasiparticle structures, some of which are isomeric. The excitation energies of the multi-quasiparticle 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 K^π=25⁺, 8-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.