Shape evolution and the role of intruder configurations in Hg isotopes within the interacting boson model based on a Gogny energy density functional

Abstract

The interacting boson model with configuration mixing, with parameters derived from the self-consistent mean-field calculation employing the microscopic Gogny energy density functional, is applied to the systematic analysis of the low-lying structure in Hg isotopes. Excitation energies, electromagnetic transition rates, deformation properties, and ground-state properties of the 172−204 Hg nuclei are obtained by mapping the microscopic deformation energy surface onto the equivalent interacting boson model Hamiltonian in the boson condensate. These results point to the overall systematic trend of the transition from the near-spherical vibrational state in lower-mass Hg nuclei close to 172 Hg, the onset of the intruder prolate configuration as well as the manifest prolate-oblate shape coexistence around the midshell nucleus 184 Hg, and a weakly oblate deformed structure beyond 190 Hg up to the spherical vibrational structure toward the near-semimagic nucleus 204 Hg, as observed experimentally. The quality of the present method in the description of the complex shape dynamics in Hg isotopes is examined.

Effects of deformation on theβ-decay patterns of light even-even and odd-mass Hg and Pt isotopes

“…1) we observe in both isotopic chains the existence of rather sharp oblate and prolate energy minima, close in energy and separated by very high energy barriers, giving raise to shape coexistence. These findings are in qualitative agreement with recent calculations [19,23,25,26,30,31]. Looking in more detail the results from different calculations, one observes differences and similarities within the various approaches.…”

“…In particular, mean-field studies of structural changes with the Gogny interaction can be found in Ref. [25] for Hg isotopes and in Refs. [23,30,31] for Pt isotopes.…”

“…Triaxiality in this mass region has also been explored systematically [19,23,25,30,31], showing that although the axial deformations seem to be the basic ingredients, triaxiality may play a role in some cases. A systematic survey of energy surfaces in the (β, γ) plane with the Gogny D1S interaction can be found in the Bruyères-leChâtel database [32].…”

Shape Coexistence in the Neutron-Deficient Even-EvenHg182−188Isotopes Studied via Coulomb Excitation

“…This resulted, amongst other things, in the observation of strong staggering in the isotope shifts in the mercury isotopes [3], the discovery of triple shape coexistence in 186 Pb [4], and an early onset of deformation in the light polonium and platinum isotopes as evidenced through laser spectroscopy (see, e.g., [5]). The global trends of these experimental findings are reproduced by theoretical descriptions, such as phenomenological shape-mixing calculations and contemporary symmetry-guided models (e.g., [6,7]), and beyond mean-field approaches [5,8,9]. However, there is a lack of direct experimental information on the nature of the quadrupole deformation or on the mixing of the states belonging to the coexisting structures.…”

Shape coexistence in the microscopically guided interacting boson model

“…Recently, the method of Ref. [31] was extended to handle shape coexistence [43] and applied to the neutron-deficient Pb [43] and Hg [44] nuclei and to some neutron-rich nuclei with mass A ≈ 100 [45,46].…”