HIGH-SPIN STATES IN W-172, W-174 AND W-176 STUDIED BY O-16, XN) REAC - DECOUPLED QUASI-PARTICLE BANDS AND BACKBENDING

High-spin states in 172W, 174W and 176W have been studied using gamma -ray techniques following (16O, xn) reactions on enriched Dy targets. The ground-state band has been shown to backbend in 174W and 175W, but not in 172W. Side-bands are populated in each nucleus, with preferential population of an odd-spin sequence in each case. The decay properties of these bands, which have negative parity, suggest that they are due to the partial decoupling of a pair of quasi-particles by the Coriolis force. The properties of the bands are used to estimate in an empirical way the properties of a rotation-aligned (i 132/)2 neutron band in order to predict the systematics of backbending due to bandcrossing.