Neutron-Rich Nuclei Beyond [sup 132]Sn: Spherical Shapes and Octupole Correlations

Abstract

Nuclear properties of nuclei with a few valence nucleons outside the doubly‐magic 132Sn core and located in the octupole correlation region have been investigated via γ‐γ‐γ coincidence measurements of prompt gamma‐ray emitted in the spontaneous fission of 252Cf with Gammasphere. The high spin level scheme of 134I has been identified for the first time. Shell model calculations reproduce the level scheme quite well. The level schemes of 137I and 139Cs have been reinvestigated and extended. Their nuclear structure is well described by realistic shell model calculations. The g‐factors of the 4+ state in 134Te, 15/2+ state in 135I, and 15/2− state in 137Xe were determined using a newly developed program for angular correlation analysis. The measured g‐factors compared favorably with shell model calculations. Octupole correlations are proposed in 141Cs and 142Cs. The variations of D0 in the Cs isotopes exhibit a pronounced drop of dipole moment with increasing neutron number.