Covariant description of shape evolution and shape coexistence in neutron-rich nuclei at

Abstract

The shape evolution and shape coexistence phenomena in neutron-rich nuclei at N ≈ 60, including Kr, Sr, Zr, and Mo isotopes, are studied in the covariant density functional theory (DFT) with the new parameter set PC-PK1. Pairing correlations are treated using the BCS approximation with a separable pairing force. Sharp rising in the charge radii of Sr and Zr isotopes at N = 60 is observed and shown to be related to the rapid changing in nuclear shapes. The shape evolution is moderate in neighboring Kr and Mo isotopes. Similar as the results of previous Hartree-Fock-Bogogliubov (HFB) calculations with the Gogny force, triaxiality is observed in Mo isotopes and shown to be essential to reproduce quantitatively the corresponding charge radii. In addition, the coexistence of prolate and oblate shapes is found in both 98 Sr and 100 Zr. The observed oblate and prolate minima are related to the low single-particle energy level density around the Fermi surfaces of neutron and proton respectively. Furthermore, the 5-dimensional (5D) col-

β-decay properties of neutron-rich Ge, Se, Kr, Sr, Ru, and Pd isotopes from deformed quasiparticle random-phase approximation

“…From the theoretical side, the equilibrium nuclear shapes in this mass region have been shown to suffer rapid changes as a function of the number of nucleons with competing spherical, axially symmetric prolate and oblate, and triaxial shapes at close energies. Both relativistic [3,4] and nonrelativistic [5][6][7][8][9] approaches agree in the general description of the nuclear structural evolution in this mass region, which is supported experimentally by spectroscopic studies [10][11][12], 2 + lifetime measurements [13][14][15], and quadrupole moments for rotational bands [15], as well as by laser spectroscopy measurements [16].…”

Effect of pairing correlations on nuclear low-energy structure: BCS and general Bogoliubov transformation

“…More details about the calculations can be found in Refs. [45,46]. indicates that the BCS ansatz gives slightly weaker pairing correlations with same pairing force.…”

Tetrahedral shapes of neutron-rich Zr isotopes from a multidimensionally constrained relativistic Hartree-Bogoliubov model

“…These nuclei are among those with N ≃ 70 and A ≃ 110 which show interesting nuclear structure properties, such as drastic changes in shapes with A and shape coexistences [40,42,49,51,63,64,94,[124][125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140][141]. The structures of nuclei around N = 70 are also of particular interest for nuclear astrophysics because neutron-rich nuclei with A ≃ 110 are around the r-process path, which is determined by the equilibrium between neutron capture and photodisintegration [142][143][144][145][146][147][148][149][150][151][152].…”

“…The structures of nuclei around N = 70 are also of particular interest for nuclear astrophysics because neutron-rich nuclei with A ≃ 110 are around the r-process path, which is determined by the equilibrium between neutron capture and photodisintegration [142][143][144][145][146][147][148][149][150][151][152]. Zr isotopes have been studied extensively with the CDFT under the assumption of reflection symmetry [94,125,127,133,135,136,139]. In these studies, the coexistence of prolate and oblate minima in potential energy curves of even-even Zr isotopes were discussed.…”