The systematics of energy ratios of successive levels of collective bands in medium- and heavy-mass even-even nuclei are studied. A measure of their deviation from the vibrational and rotational limiting values is found to have different magnitude and angular momentum dependence in the vibrational, γ-unstable and rotational regions. The usefulness of this new criterion for distinguishing between different kinds of collective behavior is demonstrated in the case of intruder and octupole bands.

• Received 31 July 1990

DOI:https://doi.org/10.1103/PhysRevC.43.R952