Triaxiality and shape dynamics in ${}^{70}$Ge

Abstract

The electromagnetic properties of low-lying states in ${}^{70}$Ge were investigated via multi-step Coulomb excitation of a ${}^{70}$Ge beam impinging on a ${}^{208}$Pb target at the ATLAS facility of the Argonne National Laboratory. A total of 27 transitional elements and six diagonal matrix elements coupling 11 low-lying states, were extracted from the measured cross sections. These were used to calculate reduced transition probabilities, spectroscopic quadrupole moments, and rotational invariant shape parameters, providing enhanced precision and expanding on previous studies. The experimental data were compared within several theoretical frameworks, including the generalized triaxial rotor model, configuration interaction shell-model calculations, and computations within the combined frameworks of relativistic density functional theory and the five-dimensional collective Hamiltonian. The results demonstrate a good agreement with the experimental data and, in conjunction with calculations using a two-state mixing model, support significant triaxiality and strong mixing between the $0_1^{+}$ and $0_2^{+}$ states. This results in the magnitudes of their respective quadrupole deformations $[{\beta }_{\text{rms}}(0_1^{+})=0.228(3),{\beta }_{\text{rms}}(0_2^{+})=0.273(1)]$ being more similar than previously observed. The implications of these results for understanding the complex shape coexistence phenomena, the role of triaxiality, and shape evolution along the Ge isotopic chain are discussed.

This article contains 15 pages and 13 figures

References in corpus (15)

• Relativistic Continuum Hartree Bogoliubov Theory for Ground State Properties of Exotic Nuclei
• New parametrization for the nuclear covariant energy density functional with point-coupling interaction
• Relativistic Nuclear Energy Density Functionals: Mean-Field and Beyond
• Thick-Restart Block Lanczos Method for Large-Scale Shell-Model Calculations
• Multi chiral-doublets in one single nucleus
• Beyond the relativistic mean-field approximation (III): collective Hamiltonian in five dimensions
• Microscopic Analysis of Nuclear Quantum Phase Transitions in the N=90 region
• Direct Evidence of Octupole Deformation in Neutron-Rich ${}^{144}$Ba
• Shape coexistence and the role of axial asymmetry in ${}^{72}$Ge
• Evidence for rigid triaxial deformation in ${}^{76}$Ge from a model-independent analysis
• Coexistence of nuclear shapes: self-consistent mean-field and beyond
• Structural evolution in germanium and selenium nuclei within the mapped interacting boson model based on the Gogny energy density functional
• Triaxiality and shape coexistence in Germanium isotopes
• A Comparison of Shell Model Results for Some properties of the Even-Even Ge Isotopes
• Shell model description of Ge isotopes