{spdf} Interacting Boson Model And Its Applications

{spdf} interacting boson model is an algebraic scheme with which the nuclear quadrupole deformation, octupole deformation and their coupling can be unifiedly described. The group structure of {spdf} IBM is discussed systematically in this thesis. The 142 group chains with physical meaning are found. Meanwhile, the hamiltonian, the branching rules of the group representation and the typical energy spectra of the SU(5), 0(6), SU(3) and O(4) limits are given.In this dissertation, the hamiltonian and electromagnetic transition operators are discussed. The most general form of these operators are presented. The normal product form of the complete set consistent of the general hamiltonian and its multipole expansion form are determined as well as the relation between these two forms. The effect of the quadrupole and octupole excitations on the characteristics of the nuclear spectra is proposed.Making use of diagonalizing the most general hamiltonian in the model space U_spdf(16), we set up a computer program package with which the energy spectra, the reduced transition rates and multipole moments of El, E2, E3 and other electromagnetic transitions can be determined in the framework of {spdf} interacting boson model. The programs have been checked with the group chain method. Using the programs, we calculate the energy spectra and the reduced transition rates of El, E2 and E3 tran-sitions of nuclei 144Ba, 146Ba, 148Sm, 150Sm, and 152Sm. The results agree with experiments quite well.By combining the {spdf} interacting boson model and the Eikonal approximation theory, we proposed an approach descibing the inelastic scattering in which the nucleus is excited from the ground state to a negative parity state by the medium energy hadron. In this scheme it is easy to determine the deformation parameter of the collective excited state with negative parity, the form factor and the scattering cross section. The scattering of 71* —mSn and tt1 —152Sm are discussed in details with this scheme. The calculated results are consistent with experiments pretty well.In the last part of this thesis, we give a brief conclusion and discussion, and predict the possibility of describing the high spin state and the superdeformed state, which are formed by the quadrupole and octupole excitations, in the framework of {spdf} interacting boson model.