High-spin structures in 155Tb and signature splitting systematics of the πh11/2 bands in odd A≈160 nuclei

The reactions Sm-152(Li-7,4n) at 45 MeV and Sn-124(S-36,p4n) at 165 MeV were used to study high-spin states of the N=90 nucleus Tb-155. Previously known bands have been greatly extended in spin (I approximate to 45 (h) over bar) and a new decoupled sequence was identified. Several band crossings or quasiparticle alignments have been observed in each of the structures, and as a result a configuration assignment has been given to the new band. B(ML)/B(E2) transition strength ratios have been extracted from the data and comparisons were made with theoretical predictions. A comprehensive analysis of the signature splitting in the energy levels and B(MI)/B(E2) ratios for the pi h(11/2) bands of the A approximate to 160 region has been performed. Possible interpretations for the observed trends in the signature splitting of these structures are discussed. [S0556-2813(98)03211-7].