A New Evidence of Interplay Between Tetrahedral and Octahedral Symmetries and Symmetry Breaking: Exotic Rotational Bands in ${}^{152}$Sm

Abstract

We report on an experimental evidence for a new, second tetrahedral band in ${}_{62}^{152}$Sm${}_{90}^{}$. It was populated via fusion evaporation reaction, ${}^{150}\mathrm{Nd}(\alpha ,2n{)}^{152}$Sm, employing 26 MeV beam of $\alpha$ particles from K-130 cyclotron at Variable Energy Cyclotron Centre, Kolkata, India. The newly observed possible mixed parity sequence with absence of E2 and strong indication of E3 transitions is consistent with the spectroscopic criteria for a tetrahedral-symmetry rotational band that could be constructed from the allowed spin-parity assignments. This structure differs from the structure of the band previously found in the same nucleus, the new one manifesting tetrahedral symmetry not accompanied by the octahedral one. Our new experimental results are interpreted in terms of group representation theory and collective nuclear-motion theory of Bohr. We propose to generalize the notion of the tetrahedral vibrational bands and believe that our new experimental results support a number of theory predictions related to nuclear tetrahedral symmetry published earlier and bring a new light into the issue of spontaneous symmetry breaking in heavy nuclei.

arXiv comment20 PAGES, 21 FIGURES

References in corpus (12)

• Nuclear Tetrahedral Symmetry: Possibly Present Throughout the Periodic Table
• Symmetry-Unrestricted Skyrme-Hartree-Fock-Bogoliubov Calculations for Exotic Shapes in N=Z Nuclei from 64Ge to 84Mo
• Nonaxial-octupole effect in superheavy nuclei
• Tetrahedral and Triangular Deformations of $Z=N$ Nuclei in Mass Region $A\sim 60-80$
• Microscopic study of tetrahedrally symmetric nuclei by an angular-momentum and parity projection method
• Tetrahedral correlations in ${}^{80}$Zr and ${}^{98}$Zr
• Nuclei with Tetrahedral Symmetry
• Spectroscopic Criteria for Identification of Nuclear Tetrahedral and Octahedral Symmetries: Illustration on a Rare Earth Nucleus
• Nuclear tetrahedral configurations at spin zero
• Hartree-Fock-Bogolyubov calculations for nuclei with tetrahedral deformation
• Efficient method to perform quantum number projection and configuration mixing for most general mean-field states
• Non-axial Octupole Deformations of N=Z Nuclei in $A\sim 60-80$ Mass Region

Cited by in corpus (1)

• Evidence of the Excited X(5)-like Critical-Point Symmetry Structures in 152Sm