Showing papers by "Jie Meng published in 2005"

Masses, deformations and charge radii: Nuclear ground-state properties in the relativistic mean field model

Abstract: We perform a systematic study of the ground-state properties of all the nuclei from the proton drip line to the neutron drip line throughout the periodic table employing the relativistic mean field model. The TMA parameter set is used for the mean-field Lagrangian density, and a state-dependent BCS method is adopted to describe the pairing correlation. The ground-state properties of a total of 6969 nuclei with Z, N ≥ 8a ndZ ≤ 100 from the proton drip line to the neutron drip line, including the binding energies, the separation energies, the deformations, and the rms charge radii, are calculated and compared with existing experimental data and those of the FRDM and HFB-2 mass formulae. This study provides the first complete picture of the current status of the descriptions of nuclear ground-state properties in the relativistic mean field model. The deviations from existing experimental data indicate either that new degrees of freedom are needed, such as triaxial deformations, or that serious effort is needed to improve the current formulation of the relativistic mean field model.

Shape evolution for Sm isotopes in relativistic mean-field theory

Abstract: The evolution of shape from the spherical to the axially deformed shapes in the Sm isotopes is investigated microscopically in relativistic mean-field theory. The microscopic and self-consistent quadrupole deformation constrained relativistic mean-field calculations show a clear shape change for the even-even Sm isotopes with N = 82-96. The potential surfaces for 148Sm, 150Sm and 152Sm are found to be relatively flat, which may be the possible critical-point nuclei. By examining the single-particle spectra and nearest-neighbor spacing distribution of the single-particle levels, one finds that the single-particle levels in 148Sm , 150Sm, and 152Sm distribute more uniformly.

Masses, Deformations and Charge Radii--Nuclear Ground-State Properties in the Relativistic Mean Field Model

Abstract: We perform a systematic study of the ground-state properties of all the nuclei from the proton drip line to the neutron drip line throughout the periodic table employing the relativistic mean field model. The TMA parameter set is used for the mean-field Lagrangian density, and a state-dependent BCS method is adopted to describe the pairing correlation. The ground-state properties of a total of 6969 nuclei with $Z,N\ge 8$ and $Z\le 100$ from the proton drip line to the neutron drip line, including the binding energies, the separation energies, the deformations, and the rms charge radii, are calculated and compared with existing experimental data and those of the FRDM and HFB-2 mass formulae. This study provides the first complete picture of the current status of the descriptions of nuclear ground-state properties in the relativistic mean field model. The deviations from existing experimental data indicate either that new degrees of freedom are needed, such as triaxial deformations, or that serious effort is needed to improve the current formulation of the relativistic mean field model.

Search for the chiral doublet bands in 122Cs

Abstract: High spin states in the odd–odd nucleus 122Cs have been studied by in-beam γ-ray spectroscopy with a 107Ag(19F,1p3n) fusion-evaporation reaction at a beam energy of 85 MeV. A previously known πh11/2 ⊗ νh11/2 yrast band was confirmed and its spin I was re-examined. A ΔI = 2 band was identified, which together with another known ΔI = 2 band forms a side band of the πh11/2 ⊗ νh11/2 yrast band. The two observed πh11/2 ⊗ νh11/2 bands are proposed as a pair of chiral doublet bands in 122Cs based on a systematic comparison with those in the neighbouring odd–odd Cs isotopes, as well as the relativistic mean field and the triaxial particle-rotor-model calculations.

High-spin states inGd152

Abstract: High-spin states of {sup 152}Gd have been studied via the {sup 148}Nd({sup 9}Be,5n){sup 152}Gd fusion-evaporation reaction at a beam energy of 54 MeV. The ground-state band, octupole band, and {beta} band have been extended up to spins 20{sup +}, 21{sup -}, and 16{sup +}, respectively. A possible aligned two quasineutron band, which becomes the yrast band above the spin 16{sup +}, was observed for the first time. The kinematic behaviors of the ground-state bands and yrast bands in {sup 152,154}Gd indicate that the shape of {sup 152}Gd may change with increasing rotational frequency and the difference of quadrupole deformations between {sup 152}Gd and {sup 154}Gd obviously reduces around the first band crossing region. These observations are consistent with the theoretical calculations using cranked Woods-Saxon-Strutinsky methods. The first band crossing observed in {sup 152}Gd can be ascribed to the alignment of a pair of i{sub 13/2} neutrons. The identical ground-state bands in {sup 152}Gd and {sup 154}Dy were extended.

Sensitivity of neutron radii in a Pb-208 nucleus and a neutron star to nucleon-sigma-rho coupling corrections in relativistic mean field theory

Abstract: We study the sensitivity of the neutron skin thickness S in a Pb-208 nucleus to the addition of nucleon-sigma-rho coupling corrections to a selection (PK1, NL3, S271, and Z271) of interactions in a relativistic mean field model. The PK1 and NL3 effective interactions lead to a minimum value of S= 0.16 fm in comparison with the original value of S= 0.28 fm. The S271 and Z271 effective interactions yield even smaller values of S= 0.11 fm, which are similar to those for nonrelativistic mean field models. A precise measurement of the neutron radius, and therefore S, in Pb-208 will place an important constraint on both relativistic and nonrelativistic mean field models. We also study the correlation between the radius of a 1.4-solar-mass neutron star and S.

Relativistic Continuum Hartree Bogoliubov Theory for Ground State Properties of Exotic Nuclei

Abstract: The Relativistic Continuum Hartree-Bogoliubov (RCHB) theory, which properly takes into account the pairing correlation and the coupling to (discretized) continuum via Bogoliubov transformation in a microscopic and self-consistent way, has been reviewed together with its new interpretation of the halo phenomena observed in light nuclei as the scattering of particle pairs into the continuum, the prediction of the exotic phenomena -- giant halos in nuclei near neutron drip line, the reproduction of interaction cross sections and charge-changing cross sections in light exotic nuclei in combination with the Glauber theory, better restoration of pseudospin symmetry in exotic nuclei, predictions of exotic phenomena in hyper nuclei, and new magic numbers in superheavy nuclei, etc. Recent investigations on new effective interactions, the density dependence of the interaction strengthes, the RMF theory on the Woods-Saxon basis, the single particle resonant states, and the resonant BCS (rBCS) method for the pairing correlation, etc. are also presented in some details.

The nuclear spin orbit interaction for the particle-state and the hole-state

Abstract: The relativisitic mean-field theory explains that the energy difference between hole-states remains constant and that between particle-states increases with neutron excess qualitatively, but not quantitatively.