Probes of axial and nonaxial hexadecapole deformation effects in nuclei around ²³⁰U

Abstract

The structure properties for even-even nuclei around 230U, locating on the hexadecapole-deformation island, are investigated by using the potential-energy-surface calculation within the framework of macroscopic-microscopic model. The impact of different deformation degrees of freedom (including axial and nonaxial quadrupole and hexadecapole deformations) on total energy, shell and pairing contributions is analyzed based on the projected energy-maps and -curves. The single-particle structure is presented and briefly discussed. To a large extent, much better agreement with experiment data and other theoretical results was obtained if the hexadecapole deformations, especially the axial one, were taken into account. Present results could provide useful keys to understand the effects of different quadrupole and hexadecapole deformations. Considering the least energy principle, the more reasonable deformation subspace is suggested to simultaneously include the octupole correlation.

Revisiting the island of hexadecapole-deformation nuclei in the A ≈ 150 mass region: focusing on the model application to nuclear shapes and masses

“…Z = 50 and N = 82, are reproduced at β 2 = 0.0. When the spherical symmetry breaks, the orbital labeled by nlj splits into j + 1/2 components and each one is typically double degenerate due to Kramers degeneracy [27]. Let us remind ourselves that the virtual crossings of single-particle levels with the same symmetries are not removed [65], but this will not prevent the level identification.…”

“…In a quadrupole-deformed nucleus, the asymptotic Nilsson quantum numbers Ω π [Nn z Λ] are often adopted, where N, n z , Λ and Ω respectively stand for the total oscillator shell quantum number, the number of oscillator quanta in the z direction (the direction of the symmetry axis), the projection of orbital angular momentum along the symmetry axis and the projection of total angular momentum (cf, e.g. [27]). It needs to be stressed that once the shape becomes somewhat complicated, the so-called main component of the wave function may not be prominent any more and the label will be meaningless in principle.…”

“…These deformation parameters play an important role in reliably describing many nuclear properties, such as nuclear mass, charge radii and moments of inertia. Some deformation parameters of a deformed nucleus can be determined by scattering measurements, cf [26,27] and references therein.…”

“…Several typical β 4 deformation regions were presented, agreeing with the calculations by Möller et al [15] at the ground states. Following such an investigation, we further studied the effects of hexadecapole deformations on the shapes of atomic nuclei around 230 U [27]-one of the prominent β 4 regions. In another recent project [32], we refitted a set of macroscopic model parameters which can improve the description of nuclear binding energies.…”

Effects of triaxial deformation on the fission barrier in the Z = 118 − 120 nuclei*

“…It can usually transform to the (β 2 , γ, β 4 ) deformation space in Bohr's parametrization [52,53] under the Lund Convention [37,50,54]. This deformation space could describe the structure properties well for even-even nuclei at A > 200 [37][38][39]55]. After the nuclear shape was specified, the macroscopic energy could be obtained, and the one-body mean-field single-particle potential could also be generated.…”