Analysis of the energy of the first four excited states of the ground- state rotational bands of the even-even lanthanon nuclei (58Ce to 70Yb) with the model of a single cluster of nucleons revolving about a sphere.

Analysis of the first four excited energy levels of the ground-state rotational bands of 82 nuclei (isotopes of the seven even-even lanthanons from 58Ce to 70Yb) has provided values of the radius of revolution of a single cluster about a sphere in each nucleus. The number of nucleons m in each cluster is taken to be 2 for neutron number N = 82 in each case for the first excited state, usually increasing by 2 with change in Z or N by +/-2, but sometimes changing by 0 or by 4 or more. The radius of revolution R decreases to a minimum (about 6.7 fm) at N approximately 78, rises sharply at N approximately 86, reaches a maximum (about 7.8 fm) at N approximately 96, and then decreases.