Isomer Spectroscopy in 216

Excited states in 216Th were investigated via prompt and delayed γ decays and the recoil-decay tagging method. The decay schemes of the Iπ=(8+), t1/2=128(8) μs, the Iπ=(11-), t1/2=615(55) ns, and the Iπ=(14+), t1/2≥130 ns isomers were established. The configuration πh9/2f7/2 is assigned to the Iπ=(8+) isomer, which implies that the h9/2 and f7/2 states are nearly degenerate. This is ascribed to increased binding of the f7/2 orbital by its coupling to a low-lying Iπ=(3-) state at Ex=1687 keV. The role of octupole and pairing correlations for a Z=92 shell closure prediction is discussed on the basis of shell model calculations