Quadrupole deformation of the nucleus and dynamic vibrations of its surface

Abstract

Based on the new Chart (database) of deformations of atomic nuclei, a systematic comparative analysis of quadrupole deformation parameters obtained by different methods for a large number of even-even nuclei is performed. It is shown that all nuclides whose quadrupole deformation parameters are deduced from the data on quadrupole moments (Q-type data) and on the reduced probability B(E2)↑ of quadrupole electric transitions 0+ → 21+ (B-type data) are clearly divided into two groups. In one of them, the data of both types show good agreement (within experimental errors) and in the other the B-type deformations are systematically (sometimes greatly) larger than the Q-type deformations. It is shown that this relationship among the data from different sources may be explained by assuming that a deformation parameter depends upon vibrations of the nuclear surface in the ground state. In this case, the B-type data, unlike the Q-type data, are believed to allow for these nuclear surface vibrations. In other words, the B-type data take into account not only static deformation, i.e., the “shape” of the nucleus, but also dynamic deformation resulting from vibrations of the nuclear surface in the ground state. The assumption that the nuclear dynamic deformation affects the nuclear shape allows one to assess “rigidity” of nuclei dividing them into two groups: “rigid” and “nonrigid”, i.e., “loose”. A comparison of the static and total deformations may yield data on nuclear properties, e.g., estimates of relationships between mass parameters and rigidity parameters.