Pochivalov, Oleksiy Grigorievich (2006-12). Description of isoscalar giant dipole resonance in nuclei. Doctoral Dissertation. Thesis uri icon

abstract

  • Applicability of the Hartree-Fock (HF) based random phase approximation (RPA) with several Skyrme effective interactions to the description of the isoscalar giant monopole (ISGMR) and the isoscalar giant dipole resonance (ISGDR) in 90Zr, 116Sn, 144Sm and 208Pb nuclei has been investigated. The existing Skyrme interactions SL1, SkM*, SGII, Sly4 and Sk255 were used. Hartree-Fock description of the ground state properties of all nuclei of interest was obtained using these Skyrme interactions. Transition strength distributions for the ISGMR and the ISGDR in nuclei of interest were calculated using coordinate space representation for the RPA in the Green's function formalism with discretized continuum. A method of projecting out the spurious state contribution from the transition strength distribution and the transition density of the ISGDR was employed to eliminate spurious state mixing, due to a not fully selfconsistent description of the particle-hole interaction within the RPA. Differential cross sections of 240 MeV alpha-particles inelastic scattering on all nuclei of interest were calculated using the folding model within the distorted wave Born approximation (DWBA). Optical potentials were obtained by folding HF ground state densities with a alpha-nucleon density dependent Gaussian interaction. Parameters of the interaction were obtained by fitting experimental angular distribution of alpha-nucleus elastic scattering. The inelastic differential cross sections were calculated using both collective and microscopic transition densities. Possible underestimations of the energy weighted sum rule for the case of the ISGDR are reported. An alternative description for the ISGDR in nuclei based on the Fermi liquid drop model (FLDM) with the collisional Fermi surface distortion was investigated. The FLDM dispersion relation was obtained from the linearized Landau-Vlasov equation. Centroid energies, E0 and E1, and widths, gamma-0 and gamma-1, of the ISGMR and ISGDR, respectively, were calculated as functions of the damping parameter using appropriate boundary conditions. Comparison of the theoretical ratios of the ISGDR and ISGMR centroid energies, E1/E0, to the experimental values resulted in a damping parameter equal to 0.5, however, systematic overestimation of energy of the ISGMR and ISGDR by 2.0-2.5 MeV was observed. The applicability of the HF-RPA to the description for the ISGDR in nuclei is confirmed.
  • Applicability of the Hartree-Fock (HF) based random phase approximation (RPA) with
    several Skyrme effective interactions to the description of the isoscalar giant monopole
    (ISGMR) and the isoscalar giant dipole resonance (ISGDR) in 90Zr, 116Sn, 144Sm and
    208Pb nuclei has been investigated. The existing Skyrme interactions SL1, SkM*, SGII,
    Sly4 and Sk255 were used. Hartree-Fock description of the ground state properties of all
    nuclei of interest was obtained using these Skyrme interactions.
    Transition strength distributions for the ISGMR and the ISGDR in nuclei of interest
    were calculated using coordinate space representation for the RPA in the Green's
    function formalism with discretized continuum. A method of projecting out the spurious
    state contribution from the transition strength distribution and the transition density of
    the ISGDR was employed to eliminate spurious state mixing, due to a not fully selfconsistent
    description of the particle-hole interaction within the RPA.
    Differential cross sections of 240 MeV alpha-particles inelastic scattering on all nuclei of
    interest were calculated using the folding model within the distorted wave Born
    approximation (DWBA). Optical potentials were obtained by folding HF ground state
    densities with a alpha-nucleon density dependent Gaussian interaction. Parameters of the
    interaction were obtained by fitting experimental angular distribution of alpha-nucleus
    elastic scattering.
    The inelastic differential cross sections were calculated using both collective and
    microscopic transition densities. Possible underestimations of the energy weighted sum
    rule for the case of the ISGDR are reported. An alternative description for the ISGDR in nuclei based on the Fermi liquid drop
    model (FLDM) with the collisional Fermi surface distortion was investigated. The
    FLDM dispersion relation was obtained from the linearized Landau-Vlasov equation.
    Centroid energies, E0 and E1, and widths, gamma-0 and gamma-1, of the ISGMR and ISGDR,
    respectively, were calculated as functions of the damping parameter using appropriate
    boundary conditions. Comparison of the theoretical ratios of the ISGDR and ISGMR
    centroid energies, E1/E0, to the experimental values resulted in a damping parameter
    equal to 0.5, however, systematic overestimation of energy of the ISGMR and ISGDR
    by 2.0-2.5 MeV was observed. The applicability of the HF-RPA to the description for
    the ISGDR in nuclei is confirmed.

publication date

  • December 2006