Puzzling questions about excited superdeformed rotational bands of atomic nuclei are answered by the two-revolving-cluster model.

Abstract

The two-revolving-cluster model provides explanations of several questions about excited superdeformed bands: restriction to the lanthanons and the Hg-Tl-Pb region and to the smaller values of the neutron number for each element, truncation of the y-ray cascades, differences in shape of the lanthanon and Hg-TI-Pb bands, alignment of quantified spins, and the existence of pairs of bands with nearly identical --ray sequences. A previously unrecognized kind of pairing (intercalation of y-ray values) is also reported and a discussion is given of the values of electric quadrupole moments.In their recent review of the y-ray energies of 56 excited superdeformed bands of lanthanon and Hg-Tl-Pb nuclei, Han and Wu (1) mention that there are at least five important physical questions concerning the systematics of superdeformations that ask for explanations. Many other physicists have raised similar questions, which are described as puzzling and as the most interesting questions in nuclear physics at the present time. I have found that the two-revolvingcluster analysis of the polyspheron model provides answers to these questions that seem to me to be reasonable. In the following sections of this paper I discuss five questions posed by Han and Wu (questions 1 to 5) as well as some other questions. The Polyspheron ModelDuring the last 26 years I have used the polyspheron model in discussing many observed properties of nuclei. This model, an extension of the a-particle model that was popular in the 1930s (Hans Bethe and others), describes a nucleus as a close-packed aggregate of spherons, which are nucleons occupying a localized s orbital (2, 3). The most common spherons are the helion, p2n2, and the triton, pn2, but p2n, pn, p, and n may also occur. Many rotational levels can be interpreted as involving a single cluster, such as a cap of six spherons about a central spheron, revolving about a completed-subshell central sphere, which does not contribute to the angular momentum. Values of the moment of inertia are given by the observed energy values or their differences. Their interpretation requires the assignment of the nucleon number of the cluster and the inclusion of the corresponding value of the radius of revolution into a system that has been developed (4-8).I found that for 35 ground-state bands it was not possible to assign acceptable values of m, the number of nucleons in a single revolving cluster, and R, the radius of revolution, to the higher rotational levels (6). A change in structure was clearly indicated, which I interpreted as the transition from one revolving cluster to two revolving clusters. I also was able to interpret the y-ray energy values for the 56 excited superdeformed bands listed by Han and Wu in the same way (8). The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.