STUDY OF BAND STRUCTURES AND CROSSINGS IN 179OS

High-spin states in 179Os have been populated by the (S-34, 5n) reacti on and were studied with the gamma-spectrometer OSIRIS. The three prev iously known bands were extended to higher spins and four new bands we re established. From branching and mixing ratios, B(M1)/B(E2) ratios a nd g(K) factors were extracted, which have been utilized for configura tion assignments. The bands show large differences in the crossing fea tures. Their alignment behaviour is probably determined by shape effec ts and the rotation alignment of an i13/2 quasineutron pair. The i13/2 quasi neutron sequences of opposite signature show a significantly di fferent backbending behaviour indicating that they do not correspond t o the same nuclear shape or that the crossing bands are not both of (n ui13/2)3 configuration.