Abstract
Background: Compared to the axially deformed nuclei, triaxially deformed ones are relatively scarce. This is mainly due to the difficulties in the identification of experimental signatures pertaining to the triaxial degree of freedom. In the nucleus , a number of rotational bands have been observed to have medium or high spin values. They have been interpreted in the macroscopic-microscopic method, to be based on triaxial minima. In particular, for a few configurations, the calculations suggested that a reorientation of the rotational axis may have occurred along the rotational bands.
Purpose: The present work aims at a quantitative description of the experimentally observed bands in , using the cranked self-consistent Skyrme-Hartree-Fock (SHF) method or cranked nuclear density functional theory (DFT). Such a study, which is still missing, will provide alternative interpretations of the structure of the bands and hence, shed new light on the triaxiality issue in connection with experimental data.
Methods: The rotational bands are described using cranked self-consistent mean-field method with SLy4 and SkM* Skyrme energy density functionals (EDFs). For SLy4 EDF, the time-odd pieces are included using Landau parameters (denoted with ). For SkM* EDF, the local gauge invariance argument has been used to determine the time-odd components of the mean field.
Results: The survey of different configurations near Fermi surface of results in 12 lowest configurations, at both positive- and negative- deformations. These are calculated to be the energetically lowest configurations. The results show that, for both EDFs, the rotational states based on positive- minimum, which is at , are lower than the respective configurations with negative- deformation. The general trends of the spin-versus- curve, and the energy-versus-spin curve reproduce well those of the experimental data. Further, for the observed bands T1–T8, the calculated results using allows the configurations of the observed bands to be assigned. The calculations predict transitional quadrupole moments, which can be used to compare with future experimental data.
Conclusions: The current cranked self-consistent mean-field calculations of the near-yrast high-spin rotational bands in reproduce well the experimental data. The results suggest that the experimentally observed bands can be assigned to the calculated bands with various configurations at the positive- deformation. The predictions of the current calculations are complementary to that of the well-known macroscopic-microscopic calculations, both of which await future experiment to verify.
1 More- Received 26 September 2018
- Revised 25 November 2018
DOI:https://doi.org/10.1103/PhysRevC.99.034304
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