Spin-parity assignments and extension of the 02+ band in 158Er

Low and medium spin collective structures in 158 Er have been studied using the 150 Sm( 12 C,4n γγ ) fusion-evaporation reaction at a beam energy of E lab = 65 MeV. A band built on the 0 2 + excitation has been established and extended to J π = 18 + from the analysis of γ - γ coincidence relationships, intensity arguments and DCO ratios. The 0 2 + band in 158 Er presents a similar trend to the 0 2 + bands in the lighter N = 90 isotones but lies about 125 keV higher. This systematic trend supports a similar configuration for the 0 2 + bands in the N = 90 isotones.