Feeding of Discrete-Line Superdeformed Bands at Very High Spin

The superdeformed band in ${}_{}{}^{149}{}_{}{}^{}\mathrm{Gd}$ has been populated with various input angular momenta and excitation energies. These, together with all other available data, indicate that the necessary criterion for populating superdeformed bands is to form cold residual nuclei at spins higher than those where the superdeformed states become yrast. In addition, the decrease in the superdeformed band intensity as it is gated by higher-energy $\gamma$ rays does not support the predictions based on a recently proposed feeding mechanism of these states.