Investigation Of The Structure Evolution And Rotational Properties Of Even-Even Nuclei In Rare Earth Region And Rf Isotopes

The main work of this thesis is based on the deformation-pairing-frequency self-consistent cranked shell model, which is so-called TRS(total-Routhian-surface)calculations, to study the shape evolution or rotational properties of the medium and superheavy nuclei. And the main content are divided into two parts: Firstly, to analysis of the equilibrium deformation of the ground state of the even-even130-140 Ce, 130-140 Nd, 130-140 Sm and 130-140 Gd in rare earth region and to study the evolution of the energy curve versus the rotational frequency. In addition, we have discussed the spin-dependent γ softness or triaxiality in yrast states of even-even132-138 Nd nuclei as well; Secondly, by studying the upbending phenomena in rapidly rotating even-even nuclei250-266 Rf in superheavy mass region, we have investigated the influence of alignment induced by the Coriolis force upon their rotational properties and concentrated on the evolution of their occupied orbitals near the Fermi surface.Investigation of shape evolution in even-even nuclei near the rare earth region: In the A=130~140 mass region, there are various shape information in these nuclei. And the reference orbital near the Fermi surface is the 1h11/2 intruder orbital with a strong shape driving effect. The protons locate in the bottom of the orbitals while the neutrons occupy the top of them. Therefore, the occupied protons or neutrons drive nuclei to oblate or prolate sphere, respectively. And they have the forcefully competition in dominating shape evolution. Firstly, we have systematically studied the deformation of ground state of the even-even 130-140 Ce,130-140 Nd,130-140 Sm and130-140 Gd isotopes and compared them with the existing theory and experimental data. Secondly, we have displayed the evolution of the energy curve of the ground state vs the γ deformation. Then, it is pointed out that there are prolate, oblate and triaxial deformation shape-coexistence phenomena.Near the Fermi surface, the protons occupy the high-j high-Ω oblate-driving orbitalsof the intruder orbitals 1h11/2 in ground state, while the neutrons locate in the high-j low-Ω prolate-driving orbitals. Nevertheless, in the cranking cases, there are strong competition in these two driving force leading to the irregular deformation. In addition, we continue to discuss the transition of the quadropole deformation in yrast state. For the odd-even staggering parameter extracted from experiment, it is in good agreement with our calculations. Note that for the indicator of the nature of the gamma degree of freedom--odd-even staggering parameter S(I), if the calculations follow the staggering rules of the previously literature, the nucleus 138 Nd would be existing the spin-dependent γ softness or triaxiality phenomena..Investigation of rotational properties in even-even nuclei250-266Rf:High-spin yrast structures of even-even superheavy nuclei 250-266 Rf are investigated by means of TRS approach in three-dimensional(β2,γ,β4) space. Firstly, we have calculated the evolution of the pairing energy gap versus neutron number, and analysis qualitatively the transition of their energy density. Then we have tentatively confirmed it by the evolution of Woods-Saxon single particle energy level curves versus quadruple deformation parameter obtained in nucleus256 Rf near its proton and neutron Fermi surface, which is used to verify the energy gap of N=152 and N=162. Secondly, we displayed the moment of inertia vs the rotational frequency of even-even nuclei250-266 Rf, and reproduce the moment of inertia of the nucleus256 Rf in experiment. In addition, we suggest that their upbending should be attributed to the alignment effect induced by the Coriolis force. Afterwards, it is demonstrated the variation of the angular momentum versus rotational frequency, together with contribution of the proton and neutron component, respectively. And the quasiparticle diagram is given subsequently as well. One can see the 1j15/2 nertron alignment is favored in light Rf isotopes, while in the heavy ones, for the simultaneous bandcrossing frequency, the 1j15/2 neutron alignment and the 1i13/2proton alignment are in a considerable competition.