Interplay of quadrupole and octupole degrees of freedom in the Gd isotopes

Abstract

A systematic theoretical investigation of the quadrupole and octupole collective properties across the Gd isotopic chain is performed employing a quadrupole-octupole axially symmetric model. These nuclei have recently attracted significant attention following the revelation that the maximum octupole collectivity in this region is located at ${}^{150}$Gd. The model parameters are optimized by fitting to the low-lying positive and negative-parity energy levels, as well as to known $E0$, $E1$, $E2$, and $E3$ transition strengths. Our primary objective is a simultaneous and unified description of quadrupole and octupole collectivity across the even-even Gd nuclei in the $84⩽N⩽96$ range, a region that includes the transition from spherical to rotational nuclear shapes. The results show a smooth evolution of the quadrupole deformation, highlighted by a distinct jump at the well-known $N=90$ critical point. The enhancement of quadrupole deformation is also correlated with the loss of non-zero octupole deformation, which is reported only for the lightest ${}^{148,150}$Gd nuclei. This translates into a fair agreement with the measured $E3$ strength, predicting a maximum $B(E3)$ value for the ${}^{152}$Gd isotope.

arXiv comment10 figures

References in corpus (19)

• Nuclear ground-state masses and deformations: FRDM(2012)
• Direct Evidence of Octupole Deformation in Neutron-Rich ${}^{144}$Ba
• E(5), X(5), and Prolate to Oblate Shape Phase Transitions in Relativistic Hartree Bogoliubov Theory
• Analytic descriptions for transitional nuclei near the critical point
• Analytic Description of Critical Point Actinides in a Transition from Octupole Deformation to Octupole Vibrations
• Description of nuclear octupole and quadrupole deformation close to the axial symmetry and phase transitions in the octupole mode
• E(5) and X(5) shape phase transitions within a Skyrme Hartree-Fock + BCS approach
• Nuclear quantum shape-phase transitions in odd-mass systems
• Octupole deformation in light actinides within an analytic quadrupole octupole axially symmetric model with Davidson potential
• Microscopic origin of reflection-asymmetric nuclear shapes
• Microscopic description of structural evolution in Pd, Xe, Ba, Nd, Sm, Gd and Dy isotopes
• Analytical description of the Coherent State Model for near vibrational and well deformed nuclei
• Two-neutron transfer reactions and shape phase transitions in the microscopically-formulated interacting boson model
• Microscopic study of neutron-rich Dysprosium isotopes
• Shape transition of Nd and Sm isotopes and neutrinoless double-beta decay nuclear matrix element of ${}^{150}$Nd
• Low-lying states in even Gd isotopes studied with five-dimensional collective Hamiltonian based on covariant density functional theory
• Beyond-mean-field description of octupolarity in dysprosium isotopes with the Gogny-D1M energy density functional
• Polarized electric dipole moment of well-deformed reflection asymmetric nuclei
• Study of shape transitions in $N\sim 90$ isotopes with beyond mean field calculations