Wang Yan-Zhao

Tensor Effect on Bubble Nuclei

In the framework of the Hartree—Fock—Bogoliubov (HFB) approach with Skyrme interactions SLy5+T, SLy5+Tw and several sets of TIJ parametrizations, i.e. the Skyrme interaction parametrizations including the tensor terms, the proton density distribution in 34Si and 46Ar nuclei is calculated with and without the tensor force. It is shown that the bubble effect in 34Si does not depend a great deal on the Skyrme parametrization and the proton density distribution in 34Si is hardly influenced by the tensor force. As to 46Ar, the SLy5+Tw parametrization favors the formation of the bubble structure due to the inversion between the 2s1/2 and 1d3/2 orbits (2s1/2−1d3/2 inversion). The inversion mechanism induced by the SLy5+Tw interaction is analyzed based on the proton single-particle spectra obtained from the SLy5 and SLy5+Tw interactions as well as the wave functions of the 2s1/2 and 1d3/2 states.

Theoretical Analysis and New Formulae for Half-Lives of Proton Emission

The proton radioactivity half-lives of spherical proton emitters are calculated by the cluster model with the contribution of a centrifugal potential barrier considered separately. The results are compared with the experimental data and other theoretical data, and good agreement is found for most nuclei. In addition, two formulae are proposed for the proton decay half-life of spherical proton emitters through the least squares fit to the experimental data available, and could reproduce the experimental half-lives successfully.

Branching Ratios of α Decay for Nuclei near Deformed Shell Closures

The generalized liquid drop model (GLDM) is extended to the region around deformed shell closure 270Hs by taking into account the excitation energy EI+ of the residual daughter nucleus and the centrifugal potential energy Vcen(r). The branching ratios of α decays from the ground state of a parent nucleus to the ground state 0+ of its deformed daughter nucleus and to the first excited state 2+ are calculated in the framework of the GLDM. The results support the proposal that a measurement of α spectroscopy is a feasible method to extract information on nuclear deformation of superheavy nuclei around the deformed nucleus 270Hs.

Gound State Properties of Nuclei in ^295118 α-Decay Chain

The properties of nuclei belonging to the α-decay chain of superheavy element 295118 have been studied in the framework of axially deformed relativistic mean field (RMF) theory with the parameter set of NL-Z2 in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, and α-decay energies Qα have been obtained and agree well with those from finite-range droplet model (FRDM). The single-particle spectra of nuclei in 295118 α-decay chain show that the shell gaps present obviously nucleon number dependence. The root-mean-square (rms) radii of proton, neutron and matter distributions change slowly from 283112 to 295118 but dramatically from 279110 to 283112, which may be due to the subshell closure at Z = 110 in 279110. The α-decay half-lives in 295118 decay chain are evaluated by employing the cluster model and the generalized liquid drop model (GLDM), and the overall agreement is found when they are compared with the known experimental data. The α-decay lifetimes obtained from the cluster model are slightly larger than those of GLDM ones. Finally, we predict the α-decay half-lives of Z = 118, 116, 114, 112 isotopes using the cluster model and GLDM, which also indicate these two models can corroborate each other in studies on superheavy nuclei. The results from GLDM are always lower than those obtained from the cluster model.

Tensor Force Effect on Shape Coexistence of N = 28 Neutron-Rich Isotones

The tensor force effect on potential energy surfaces of the N = 28 neutron-rich isotones is investigated by using the deformed Skyrme—Hartree—Fock—Bogoliubov approach with the T22 interaction. It is found that, without the tensor force, 40Mg and 46Ar have prolate and spherical ground states, respectively. The ground states of 42Si and 44S are oblate. The shape coexistence in 40Mg, 42Si and 44S is evident. However, the ground state deformations of these isotones are not changed and the shape coexistence in 42Si and 44S vanishes when the tensor force is switched on. Taking 42Si as an example, the disappearance of the shape coexistence is understood by analyzing the tensor force effect on the shell correction energies.

α-decay half-lives of superheavy nuclei and general predictions

The generalized liquid drop model (GLDM) and the cluster model have been employed to calculate the alpha-decay half-lives of superheavy nuclei (SHN) using the experimental alpha-decay Q values. The results of the cluster model are slightly poorer than those from the GLDM if experimental Q values are used. The prediction powers of these two models with theoretical Q values from Audi et al. (Q(Audi)) and Muntian et al. (Q(M)) have been tested to find that the cluster model with Q(Audi) and Q(M) could provide reliable results for Z > 112 but the GLDM with Q(Audi) for Z <= 112. The half-lives of some still unknown nuclei are predicted by these two models and these results may be useful for future experimental assignment and identification.

Quark distributions in nuclei and nuclear effects on nucleon structure functions

Extended quark distribution functions are presented obtained by fitting a large amount of experimental data of the l-A DIS process on the basis of an improved nuclear density model. The experimental data of l-A DIS processes with A ≥ 3 in the region 0.0010 ≤ x ≥ 0.9500 are quite satisfactorily described by using the extended formulae. Our knowledge of the influence of nuclear matter on the quark distributions is deepened.