Role of F-spin multiplets in identical band phenomena in normal deformed nuclei

Abstract

We have carried out a systematic study of F-spin multiplets having similar product of their valence nucleons (i.e., NpNn-values) to extract the prominent features which are responsible in generating the identical rotational bands among them. It has been established by us from the experimental data of rare-earth region that a subsequent addition of proton pair in an isotonic set of nuclei increases their (i.e., isotones) pairing contribution whereas a reversing trend has been seen while adding a neutron pair in an isotopic set. Similar type of opposite trends have also been observed in their quadrupole deformations while adding a pair of proton and neutron, respectively, in an isotone and isotope. Thus, a simultaneous addition of both proton and a neutron pair in any one of the F-spin multiplet does not alter the pairing contribution as well as deformation structure of a newly emerging F-spin multiplet provided these multiplets belong to generalized mirror pair having same NpNn products and hence the identicity prevails between their rotational spectra. These experimentally observed opposing trends of pairing correlations and deformation parameters with the addition of a particular nucleon pair in an isotone and isotope, respectively, are also supported by our cranking model calculations. These systematic studies together with the cranking model calculations have further been extended to explore the possibilities of obtaining the identical band structures between odd-A and neighboring even-even nuclei.