γ−γ energy correlations in 167,168Hf observed with two compton-suppression spectrometers

The γ−γ energy correlation matrix obtained from 159Tb(14N,xn)reactions at 95 MeV exhibits a low-intensity central valley with smoothly decreasing width when the rotational frequency increases, indicating an increasing collective moment of inertia. Enhanced intensities in valley at h ω = 0.42 and 0.52 MeV are observed for the first time in the HF isotopes and are interpreted as due to band crossings which may involve i 13 2 ,f 7 2 neutron and h 11 2 proton or higher orbital.