Interacting excited rotational bands

The role of the rotating mean field and residual interactions is discussed on the basis of recent experimental interaction matrix elements and distribution of level distances. Based on a careful identification of the rotational bands in four rare-earth nuclei, carried out earlier, most of the interactions are found to be generated by a two-body residual interaction. Some hindrance is observed with respect to changes in the K quantum number. Level distance distributions address in a more general way the question of the independence of excitations within rotational states. Both types of experimental information, band interactions and level distances, are in general accordance with mean field bands interacting with a standard surface-delta interaction.