Investigation Of Phenomenological Dispersive Optical Model

A new rotor model based on rigid model and soft rotator model is ap-plied to the analysis of low-lying excited levels of Tungsten isotopes(including both even-even and odd A nuclei).Meanwhile a dispersive isospin-dependent coupled-channels optical-model potential is derived for tungsten isotopes from 100 keV to 200 MeV.Excellent agreement in the whole energy range between calculations and the experimental data of neutron-induced total cross sections for 182,183,184,186W,178Hf,and 181Ta nuclei is obtained.Elastic and inelastic scat-tering angular distributions and analyzing powers for both neutron-and proton-induced reactions are also shown to be in good agreement with experimental data.Furthermore the nuclear volume conservation is considered and verified in the calculation of cross sections.With this consideration.the phenomeno-logical radii dependence on nuclear mass is removed from the regional potential parameters.This thesis is also tried to unify the description of the bound state and the scattering state for double magic nucleus 208Pb by one potential.The real part of the dispersive optical model potential is used to calculate the bound states based on shell model.The effect of individual dispersion correction terms on the calculation of the single particle states is discussed.A set of optical model parameters is obtained,which can reasonably describe both scattering data and bound states for 208Pb.Furthermore these optical potential parameters are re-adjusted,which improved much the calculation results of single particle states.Meanwhile the calculations of root mean square radius and single particle density also show good agreement with measurement.In order to further improve the description of scattering and bound states,the non-locality of the real potential and the shell-gap on the imaginary potentials near Fermi energy are considered,where a more physical form of Hartree-Fock potential with non-locality and imaginary potential are introduced.This modi-fied potential for Pb-Bi isotopes shows the better description of the single particle bound energy level and scattering neutron total cross section for 208Pb than the previous work.The modified potential gives also a good description of nucleon scattering data on near-magic targets 206,207Pb and 209Bi.