HIGH-SPIN STRUCTURES IN TB-155 AND SIGNATURE SPLITTING SYSTEMATICS OFTHE PI-H(11 2) BANDS IN ODD A-APPROXIMATE-TO-160 NUCLEI/

The reactions Sm-152(Li-7,4n) at 45 MeV and Sn-124(S-36,p4n) at 165 Me V were used to study high-spin states of the N=90 nucleus Tb-155. Prev iously known bands have been greatly extended in spin (I approximate t o 45 (h) over bar) and a new decoupled sequence was identified. Severa l band crossings or quasiparticle alignments have been observed in eac h of the structures, and as a result a configuration assignment has be en given to the new band. B(ML)/B(E2) transition strength ratios have been extracted from the data and comparisons were made with theoretica l 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 t he A approximate to 160 region has been performed. Possible interpreta tions for the observed trends in the signature splitting of these stru ctures are discussed. [S0556-2813(98)03211-7].