Quantitative studies of continuum gamma-ray correlations in ${}_{}{}^{170}{}_{}{}^{}\mathrm{Hf}$

We have studied the two-dimensional energy correlation of the continuum γ rays in ${}_{}{}^{170}{}_{}{}^{}\mathrm{Hf}$ produced in a heavy-ion fusion reaction. The γ rays were measured with an array of Compton-suppressed Ge detectors and the Spin Spectrometer. A quantitative analysis has been carried out on the properties of the peaks and dips in the correlation spectra. The results indicate the existence of at least two widths in the γ-ray energy distribution: a narrow width of about 20 keV, most likely originating from decay along different discrete bands near the yrast line, and a wide width of about 200 keV from mixed states at higher excitation energy. Theoretical calculations including the effect of level mixing and fluctuations in rotational frequency and moment of inertia give results in general agreement with the experiment.