Three-Photon Correlations in Rotational Nuclei

We have studied the correlations among energies of three $\gamma$-rays emitted by high-spin nuclear states. The correlation features (ridges and dip) in coincidence with two $\gamma$ rays of a given energy are found to be the same, within our statistics, as those in coincidence with a single $\gamma$ ray of that energy. We believe that this implies that the full $\gamma$-ray spectrum is a mixture of some essentially undamped rotational cascades and some rather strongly damped ones.