Systematics of odd-even staggering in γ-bands as a test for phenomenological collective models

The systematic behavior of the odd-even staggering in γ bands of even-even rare earths has been analyzed. The displacement of the odd-spin levels relative to their even-spin neighbors has been studied as a function of the neutron number N for various isotopic chains, and as a function of the nuclear spin I in each nucleus. Different behavior is observed in the vibrational and rotational limits. The observed simple systematics in the deformed limit are used as a test for symmetry-conserving three-body interactions in the SU(3) limit of the interacting boson model, with positive results. (orig.)