Charge Exchange Spin-Dipole Excitations of 90Zr and 208Pb and Neutron Matter Equation of State

Charge exchange spin-dipole (SD) excitations of $^{90}$Zr and $^{208}$Pb are studied by using a Skyrme Hartree-Fock(HF) + Random Phase approximation (RPA). The calculated spin-dipole strength distributions are compared with experimental data obtained by $^{90}$Zr (p,n) $^{90}$Nb and $^{90}$Zr (n,p) $^{90}$ Nb reactions. The model-independent SD sum rule values of various Skyrme interactions are studied in comparison with the experimental values in order to determine the neutron skin thickness of $^{90}$Zr. The pressure of the neutron matter equation of state (EOS) and the nuclear matter symmetry energy are discussed in terms of the neutron skin thickness and peak energies of SD strength distributions.Comment: 26pages, 10figure

Protoneutron stars in the Brueckner-Hartree-Fock approach and finite-temperature kaon condensation

We study the properties of hot neutrino-trapped beta-stable stellar matter using an equation of state of nuclear matter within the Brueckner-Hartree-Fock approach including three-body forces, combined with a standard chiral model for kaon condensation at finite temperature. The properties of (proto)neutron stars are then investigated within this framework.Comment: 10 pages, 5 figures, 2 tables, PRC in pres

Properties of Zr hypernuclei in deformed Skyrme Hartree-Fock approach

National Natural Science Foundation of China [10605018]; New Century Excellent Talents in University [NCET-07-0730]Properties of the even-N Zr isotopes and their corresponding single-Lambda and double-Lambda hypernuclei are studied in the deformed Skyrme-Hartree-Fock approach. Binding energy, the two-neutron separation energies, radii are studied from beta-stable zone to the neutron drip line in this paper. The neutron drip line nuclei predicted with SLy4 and SkI4 interactions are (122)Zr and (138)Zr, respectively. The neutron drip line of single-Lambda and double-Lambda hypernuclei are (139)(Lambda)Zr and (142)(2 Lambda)Zr with SkI4 interaction, respectively. The predicted hyperon drip line hypernuclei with (80)Zr and (138)Zr cores ads (100)(20 Lambda)Zr and (188)(50 Lambda)Zr, respectively

Effect of Tensor Force on the Halo Structure of 29Ne and 31Ne

The structure of Ne isotopes has been investigated by using deformed skyrme—Hartree—Fock (SHF) method and BCS approximation. Especially the effect of tensor force on the halo structure of 29Ne and 31Ne is discussed. To this end, the tensor contributions are considered to the energy density function and the single particle potential in SHF theory. For comparison, four Skyrme interactions are used: SLy5 and SGII without tensor force, and SLy5+T and SGII+T with tensor force. The results indicate that the inclusion of tensor force shows a more pronounced halo structure for 31Ne.Supported by National Natural Science Foundation of China under Grant Nos. 10975116 and 1127516

Weakly bound neutrons and quadrupole response function in the many-body pair correlation of neutron drip line nuclei

A simplified model of the Hartree-Fock Bogoliubov (HFB) equation with surface-type or volume-type pairing is solved in coordinate space with the correct asymptotic boundary conditions. By using the resulting HFB wavefunctions, the low-energy quadrupole (L = 2) response function is studied for the system with weakly bound s and d neutrons. As the binding energy of the neutrons becomes small or approaches zero, the discrete solutions of the HFB equation disappear. Then, without any further correlation ( for example, random phase approximation ( RPA) correlation), the threshold quadrupole response becomes broader and moves toward very low excitation energies, while the total strength increases very rapidly. The important role of the continuum character of the upper component u(lj) (r) of the HFB s(1/2) wavefunction in the increasing strength is pointed out. The large and broad quadrupole response with a very low peak energy is expected for neutron drip line nuclei with N approximate to 56 and Z approximate to 28, of which both the neutron 2d(5/2) and 3s(1/2) orbits may be weakly bound in the Hartree-Fock (HF) potential

Level statistics for the even-even Yb isotopes

National Natural Science Foundation of China [10605018]; New Century Excellent Talents in University [NCET-07-0730]The level statistics of the even-even Yb isotopes are studied by using the energy levels calculated by the projected shell model. The spectrum of intrinsic states and band energies are also studied to discuss the generation of chaoticity. The energy dependence of the chaoticity is investigated, and a chaos to order transition is found

Three-body forces and neutron star structure

We calculate the nucleonic equation of state within the Brueckner-Bethe-Goldstone formalism using the Argonne v(18) two-body interaction and a three-body interaction. We adopt two different three-body forces: the phenomenological Urbana IX model and a microscopic meson-exchange force including nucleon virtual excitations and nucleon-antinucleon excitations. We compare their respective predictions regarding the structure of neutron stars, in particular the mass-radius relation

Possible shape coexistence and magnetic dipole transitions in C-17 and Ne-21

Japanese Ministry of Education, Culture, Sports, Science and Technology [C(2) 18540290, 20540277]; National Science Foundation of China [10605018]; New Century Excellent Talents in University [NCET-07-0730]Magnetic dipole (M1) transitions of N=11 nuclei (17)C and (21)Ne are investigated by using shell model and deformed Skyrme Hartree-Fock + blocked BCS wave functions. Shell model calculations predict well observed energy spectra and magnetic dipole transitions in (21)Ne, while the results are rather poor to predict these observables in (17)C. In the deformed HF calculations, the ground states of the two nuclei are shown to have large prolate deformations close to beta(2)=0.4. It is also pointed out that the first K(pi)=1/2(+) state in (21)Ne is prolately deformed, while the first K(pi)=1/2(+) state in (17)C is predicted to have a large oblate deformation close to the ground state in energy, We point out that the experimentally observed large hindrance of the M1 transition between I(pi)=1/2(+) and 3/2(+) in (17)C can be attributed to a shape coexistence near the ground state of (17)C

Nuclear structure of Hf-178 related to the spin-16, 31-year isomer

The projected shell model is used to study the multi-quasiparticle and collective excitations of Hf-178. With an axially symmetric basis, the spin-16 isomer at 2.4 MeV appears to be well separated in energy/spin space from other configurations. However, projected energy surface calculations suggest that Hf-178 has significant softness to axially asymmetric shapes, which can strongly modify the level distribution. The implications for photodeexcitation of the isomer are discussed. (C) 2004 Elsevier B.V. All rights reserved

Energy level statistics in particle-rotor model

Energy level statistics of a system consisting of six particles interacting by delta force in a two-j model coupled with a deformed core is studied in particle-rotor model. For single-j shell (i(13/2)) and two-j shell (g(7/2) + d(5/2)) the exact energies for our statistical analysis are obtained from a full diagonalization of the Hamiltonian, while in two-j case (i(13/2) + g(9/2)) the configuration truncation is used. The nearest-neighbor distribution of energy levels and spectral rigidity are studied as the function of spin. The results of single-j shell are compared with those in two-j case. It is showed that the system becomes more regular when single-j space (i(13/2)) is replaced by two-j shell (g(7/2) + d(5/2)) although the basis size of the configuration space is unchanged. The degree of chaoticity of the system, however, changes slightly when configuration space is enlarged by extending single-j shell (i(13/2)) to two-j shell (i(13/2) + g(9/2))