X. Z. Zhang

Evolution of deformations in medium-mass nuclei

Evolution of quadrupole deformations in sd- and pf-shell nuclei with mass A=18-56 is studied by using deformed Skyrme Hartree-Fock model with pairing correlations. We point out that the quadrupole deformations of the nuclei with the isospin T=0 and T=1 show strong mass number dependence as a clear manifestation of dynamical evolution of deformation in nuclear many-body systems. The competition between the deformation driving particle-vibration coupling and the closed-shell structure is shown in a systematic study of the ratios between the proton and neutron deformations in nuclei with T=|T{sub z}|=1. Calculated quadrupole and hexadecapole deformations are compared with shell model results and available experimental data. A relation between the skin thickness and the intrinsic Q{sub 2} moments is also discussed.

Polarization charge of O isotopes

Isospin dependence of polarization charges in O isotopes is studied based on a microscopic particle-vibration coupling model in which the Hartree–Fock single-particle wavefunctions and RPA quadrupole strengths are used. Both isoscalar and isovector parts are included in the vertex of particle-vibration coupling. The effects of the different possible dynamical structures at a given excitation energy on polarization charges are also discussed. A large quenching of the polarization charges is found with a large value of (N − Z)/A for most single particle orbits. It is also found that the polarization charges are sensitive to the binding energy of the single particle orbit.

Quenching of Gamow-Teller strength due to tensor correlations in {sup 90}Zr and {sup 208}Pb

We performed self-consistent Hartree-Fock plus random-phase approximation (HF+RPA) calculations for charge-exchange 1 + states in 90 Zr and 208 Pb by using Skyrme interactions with tensor terms. We employed a parameter set in which the tensor terms are added to the SGII interaction. It is pointed out that Gamow-Teller (GT) states can couple strongly with the spin-quadrupole (SQ) I states in the high-energy region above E x = 30 MeV due to the tensor interactions. As a result of this coupling, more than 10% of the GT strength is shifted to the energy region above 30 MeV, and the main GT peak is moved 2 MeV downward. At the same time, the main SQ 1 + peak is moved upward by more than 10 MeV due to the tensor correlations. Schematic separable interactions are proposed to elucidate the quenching mechanism induced by the tensor interaction on the GT state.

Evolution of deformations in SD and PF shell nuclei

In the frame of deformed Skyrme Hartree-Fock (HF) model with pairing correlations, the strong mass number dependence of quadrupole deformations in sd and pf shell nuclei with mass A=(16 ~ 56) is studied as a clear manifestation of the evolution of nuclear deformation in nuclear many-body systems. The competition between the deformation driving particle-vibration coupling and the shell structure is shown by a systematic study on the ratios of the protons to neutrons quadrupole moments in nuclei with T=|Tz|=1. The mass number dependence of deformations obtained by deformed HF calculations is compared with the results of shell model and experimental data.