High-spin states and two-quasiparticle structure in 172Hf

Five rotational bands in 172Hf have been observed to high spin following the 160Gd(16O, 4n)172Hf reaction, using γ-γ coincidence techniques. The ground-state band is extended to spin 20+ without backbending, in contrast to the neighbouring even-even isotones. The most strongly populated side-band, consisting of separated odd-spin and even-spin sequences, appears to result from the partial decoupling of an i132 neutron. Three other bands are identified with the following band-heads: an 8− state at 2006 keV with 163 ns half-life; a 6+ state at 1685 keV with a half-life < 16 ns; and a level at 1857 keV with spin 4, 5, 6 or 7 and a half-life < 16 ns. The differences between the bands are discussed in terms of the influence of Coriolis forces and the two-quasiparticle level structure.