C4symmetry effects in nuclear rotational motion

We discuss the appearance of ΔI=2 staggering effects in the γ-ray energies of some superdeformed bands as due to the mixing of a series of K bands. These bands are described by the rotational Hamiltonian of a symmetric top having a fourfold symmetry axis. Using the known properties of superdeformed bands we have found limits to the possible values of the model parameters by the analysis of effective moments of inertia, deviations from the I(I+1) rigid-rotor behavior and B(E2) values. Our results indicate that the value of ${\mathcal{I}}_3$, the moment of inertia due to the ${\mathit{Y}}_{44}$ deformation, is close to that expected for a rigid ellipsoid.