Shape co-existence and structural evolution of the Vi_(13/2) band in ~(157)Yb

摘要

The high-spin states of ~(157)Yb have been studied via the reaction of ~(144)Sm(~(16)O, 3n) at ~(16)O energy of 90 MeV using techniques of in-beam γ-ray spectroscopy. Measurement of γ- γ-t coincidences was performed with 11 BGO(AC)HPGe detectors. Based on the γ-γ coincidence relationships and the measured results of γ-ray anisotropies and DCO ratios, the level scheme for ~(157)Yb was established. The shape co-existence and structural evolution of the Vi_(13/2) band with increasing angular momentum in ~(157)Yb have been discussed. The sys-tematics of the Vi_(13/2) bands in the N=87 odd-A isotones have been compared.