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Nuclear Theory·nucl-th

Monday·November 25, 2019

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    Low-energy isoscalar dipole response of heavy nuclei within kinetic model

    V.I.Abrosimov · O.I.Davydovska

    The low-energy isoscalar dipole response of heavy spherical nuclei is studied by using a semiclassical model, based on the solution of the linearized Vlasov kinetic equation for finite Fermi systems. In this translation-invariant model the excitations of the center of mass motion are exactly separated from the internal ones. The low-energy dipole strength function displays three resonance structures in the energy region up to 15 MeV. Calculations of the velocity fields associated with the resonance structures at the centroid energies show a vortex (toroidal) character of two overlying resonances, while the origin of the lowest isoscalar dipole resonance structure is related to the dipole single-particle excitations. Its centroid energy is close to the minimum energy of the dipole single-particle spectrum. The main toroidal resonance gives a qualitative description of the low-energy isoscalar dipole resonance observed in heavy spherical nuclei.

    nucl-th0 citations
  2. 02

    Quenching factor of Gamow-Teller and spin dipole giant resonances

    Li-Gang Cao · Shi-Sheng Zhang · H. Sagawa

    Gamow-Teller (GT) and spin-dipole (SD) strength distributions of four doubly magic nuclei Ca, Zr, Sn and Pb are studied by the self-consistent Hartree-Fock plus random phase approximation (RPA) method. The Skyrme forces SAMi and SAMi-T without/with tensor interactions are adopted in our calculations. The calculated strengths are compared with available experimental data. The RPA results of GT and SD strengths of all four nuclei show fine agreement with observed GT and SD resonances in energy. A small GT peak below the main GT resonance is better described by the Skyrme interaction SAMi-T with the tensor terms. The quenching factors for GT and SD are extracted from the comparisons between RPA results and experimental strengths. It is pointed out that the quenching effect on experimental SD peaks is somewhat modest compared with that on GT peaks in the four nuclei.

    nucl-thPRC(2019)·15 citations
  3. 03

    An approximation to the Woods-Saxon potential based on a contact interaction

    C. Romaniega🇪🇸 · M. Gadella🇪🇸 · R. M. Id Betan🇦🇷 · L. M. Nieto🇪🇸

    We study a non-relativistic particle subject to a three-dimensional spherical potential consisting of a finite well and a radial - contact interaction at the well edge. This contact potential is defined by appropriate matching conditions for the radial functions, thereby fixing a self adjoint extension of the non-singular Hamiltonian. Since this model admits exact solutions for the wave function, we are able to characterize and calculate the number of bound states. We also extend some well-known properties of certain spherically symmetric potentials and describe the resonances, defined as unstable quantum states. Based on the Woods-Saxon potential, this configuration is implemented as a first approximation for a mean-field nuclear model. The results derived are tested with experimental and numerical data in the double magic nuclei Sn and Pb with an extra neutron.

    nucl-thquant-phEur.Phys.J.Plus(2020)·8 citations
  4. 04

    Influence of resonances on the B(n,gamma)B capture reaction rate. III. Capture to the 2nd, 3rd and 4th excited state of B

    S.B. Dubovichenko · N.A. Burkova · A.V. Dzhazairov-Kakhramanov

    Within the framework of the modified potential cluster model with a classification of orbital states according to Young diagrams, the possibility of data description of the radiative neutron capture on 11B to the second excited state of 12B at 1.67365 MeV (2-) and prediction absentee of experimental data for the total cross sections to the third and fourth excited state of 12B at 2.6208 MeV (1-) and 2.723 MeV (0+) for reaction energy of 10 meV (1 meV = 10-3 eV) to 7 MeV was considered. The reaction rate in the temperature range of 0.01 to 10.0 T9 is calculated on the basis of obtained cross sections, which take into account resonances up to 5 MeV. It is shown, that low-lying resonances exercise a significant influence to the capture reaction rate. The approximation of the calculation reaction rate is carried out by the simple analytic formula.

    nucl-th1 citation

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