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Subjects: Physics >> Nuclear Physics

The ground state properties including radii, density distribution and one neutron separation energy for C, N, O and F isotopes up to the neutron drip line are systematically studied by the fully self-consistent microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) theory. With the proton density distribution thus obtained, the charge-changing cross sections for C, N, O and F isotopes are calculated using the Glauber model. Good agreement with the data has been achieved. The charge changing cross sections change only slightly with the neutron number except for proton-rich nuclei. Similar trends of variations of proton radii and of charge changing cross sections for each isotope chain is observed which implies that the proton density plays important role in determining the charge-changing cross sections. |

Isospin and Z1/3 Dependence of the Nuclear Charge Radii

S.Q. Zhang; J. Meng; S.-G. Zhou; J.Y. ZengSubjects: Physics >> Nuclear Physics

Based on the systematic investigation of the data available for A ≥ 40, a Z1/3 dependence for the nuclear charge radii is shown to be superior to the generally accepted A1/3 law. A delicate scattering of data around Rc/Z1/3 is infered as owing to the isospin effect and a linear dependence of Rc/Z1/3 on N/Z ( or (N ? Z)/2 ) is found. This inference is well supported by the microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) calculation conducted for the proton magic Ca, Ni, Zr, Sn and Pb isotopes including the exotic nuclei close to the neutron drip line. With the linear isospin dependence provided by the data and RCHB theory, a new isospin dependent Z1/3 formula for the nuclear charge radii is proposed. |

Pseudospin symmetry and its approximation in real nuclei

T.S. Chen; H.F. Lu; J. Meng; and S.-G. ZhouSubjects: Physics >> Nuclear Physics

The origin of pseudospin symmetry and its broken in real nuclei are discussed in the relativistic mean field theory. In the exact pseudospin symmetry, even the usual intruder orbits have degenerate partners. In real nuclei, pseudospin symme- try is approximate, and the partners of the usual intruder orbits will disappear. The difference is mainly due to the pseudo spin-orbit potential and the transition between them is discussed in details. The contribution of pseudospin-orbit potential for intruder orbits is quite large, compared with that for pseudospin doublets. The disappearance of the pseu- dospin partner for the intruder orbit can be understood from the properties of its wave function. |

Test of Pseudospin Symmetry in Deformed Nuclei

J.N. Ginocchio; A. Leviatan; J. Meng; Shan-Gui ZhouSubjects: Physics >> Nuclear Physics

Pseudospin symmetry is a relativistic symmetry of the Dirac Hamiltonian with scalar and vector mean fields equal and opposite in sign. This symmetry imposes constraints on the Dirac eigen- functions. We examine extensively the Dirac eigenfunctions of realistic relativistic mean field calcu- lations of deformed nuclei to determine if these eigenfunctions satisfy these pseudospin symmetry constraints. |

Subjects: Physics >> Nuclear Physics

The critical point nuclei in Sm isotopes, which marks the first order phase transition between spherical U(5) and axially deformed shapes SU(3), have been investigated in the microscopic quadrupole constrained relativistic mean field (RMF) model plus BCS method with all the most used interactions, i.e., NL1, NL3, NLSH and TM1. The calculated potential energy surfaces show a clear shape transition for the even-even Sm isotopes with N = 82 ? 96 and the critical point nuclei are found to be 148Sm, 150Sm and 152Sm. Similar conclusions can also be drawn from the microscopic neutron and proton single particle spectra. |

Subjects: Physics >> Nuclear Physics

Single-particle resonant states in spherical nuclei are studied by an analytic continuation in the coupling constant (ACCC) method within the framework of the self-consistent relativistic mean field (RMF) theory. Taking the neutron resonant state ν1g9/2 in 60Ca as an example, we examine the analyticity of the eigenvalue and eigenfunction for the Dirac equation with respect to the coupling constant by means of a Pad ?e approximant of the second kind. The RMF-ACCC approach is then applied to 122Zr and, for the first time, this approach is employed to investigate both the energies, widths and wave functions for l ?= 0 resonant states close to the continuum threshold. Predictions are also compared with corresponding results obtained from the scattering phase shift method. |

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

J. Meng; H. Toki; S. G. Zhou; S. Q. Zhang; W. H. Long; L. S. GengSubjects: Physics >> Nuclear Physics

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 micro- scopic 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 restora- tion 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. |

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

J. Meng; H. Toki; S. G. Zhou; S. Q. Zhang; W. H. Long; L. S. GengSubjects: Physics >> Nuclear Physics

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 micro- scopic 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 restora- tion 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. |

Multi-chiral doublets in one single nucleus

J. Terasaki; S. Q. Zhang; S. G. Zhou; J. MengSubjects: Physics >> Nuclear Physics

Adiabatic and configuration-fixed constraint triaxial relativistic mean field (RMF) approaches are developed for the first time and a new phenomenon, the existence of multi-chiral doublets (MχD), i.e., more than one pairs of chiral doublets bands in one single nucleus, is suggested for 106Rh based on the triaxial deformations together with their corresponding proton and neutron configurations. |

Giant halo in relativistic and non-relativistic approaches

J. Terasaki; S. Q. Zhang; S. G. Zhou; J. MengSubjects: Physics >> Nuclear Physics

The phenomena of giant halo and halo of neutron-rich even-Ca isotopes are investigated and compared in the framework of the relativistic continuum Hartree-Bogoliubov (RCHB) and non- relativistic Skyrme Hartree-Fock-Bogoliubov (HFB) calculations. With two parameter sets for each of the RCHB and the Skyrme HFB calculations, it is found that although halo phenomena exist for Ca isotopes near neutron drip line in both calculations, the halo of the Skyrme HFB calculations starts at a more neutron-rich nucleus than that of the RCHB calculations, and the RCHB calculations have larger neutron root-mean-square (rms) radii systematically in N ≥ 40 than those of the Skyrme HFB calculations. The former difference comes from difference in shell structure. The reasons for the latter can be partly explained by the neutron 3s1/2 orbit, which causes more than 50 % of the difference among the four calculations for neutron rms radii at 66Ca. |