Coupling of the angular momenta of the ground and K = 2− octupole bands in 180W

Abstract

An i n te rp re tab le anomaly in the energy systematics of the h igh-spin states of the K = 2" Octupole band in 180W was studied fo l low ing the populat ion of these states in the react ion 181Ta(p,2ny)180W wi th 17-MeV protons from the Livermore cyc lograa f f . Standard in-beam yray spectroscopic techniques included prec is ion energy measurements wi th coaxia l and LEPS Ge(Li) detectors, l i f e t i m e measurements wi th a reso lu t ion of ~7 ns and y-¥ coincidence studies using two 10% coaxial Ge(Li) detec tors . Our level scheme contains the prev ious ly assigned I K = 2 band to high spin. There is an obvious energy stagger ing of the even and odd members of this band. The usual backbending plot (2~}/~ 2 vs (h~) 2 = (~E/2) 2) of the ground-state and K = 2bands reveals this staggering more dramatically. The K = 2band breaks into evenand oddspin bands which parallel each other (with even spins lower) with l i t t l e backbending tRndency up to spin 14in spite of considerable backbending tendency in the ground-state band. C