Applicaions Of Mean-field Plus Nearest-orbit Pairing Interaction Model To Well-deformed Nuclei

Pairing is an important residual interaction in nuclear physics. Typically, after adopting a mean-field approach, the pairing interaction is treated approximately using either Bardeen-Cooper-Schrieffer (BCS) or Hartree-Fock-Bogolyubov (HFB) methods, sometimes in conjunction with correction terms evaluated within the Random-Phase Approximation (RPA). However, both BCS and HFB approximations suffer from serious difficulties, the non-conservation of the number of particles being one that can lead to serious problems, such as spurious states, non-orthogonal solutions, etc. Another problem with these approximations is related to the fact that both BCS and the HFB methods break down for an important class of physical situations. A remedy in terms of particle number projection complicates the algorithms considerably, often without yielding a better description of higher-lying excited states that are a natural part of the spectrum of the pairing Hamiltonian.In this thesis, in order to overcome the above drawbacks, an exactly solvable mean-filed plus nearest-orbit pairing model for the description of well-deformed nuclei is used and applied to rare-earth and actinide regions. Binding energies, pairing excitation energies of 158-171 Er i60-i78Yb) i70-i83Hfj 226-234^230-240^ 236-243pu isotopes are calculated andcompared with the corresponding experimental values. Nuclear moment of inertia in the model is also derived. As approximation, pairing excitation of protons, interactions between protons and neutrons, and the quadrupole-quadrupole interaction are not considered. The calculated values of binding-energies and the lower-lying pairing excitation energies of actinide nuclei are basically very close to the corresponding experimental values. While for rare-earth region, higher pairing excitation energies still need to be farther investigated.