Production Cross Sections Of Superheavy Nuclei And Rotational Properties Of No Isotopes

Recently, with the development of particle acceleration and radiation detection technology, much process has been made on the study of superheavy nuclei. The investigation of the production cross sections and structural properties for superheavy nuclei will be useful for the experimental research and is very important to test and develop the related theoretical models. The main content of this thesis consists of two parts. Firstly, the synthesis of superheavy elements is studied within the dinuclear system (DNS) concept. Especially, the evaporation residue cross sections of some unknown nuclei are predicted. Moreover, the optimal beam energies and the projectile-target pairs leading to larger cross sections are given in selected reaction systems. Secondly, the rotational properties of the Z=102No isotopes have been investigated systematically using total Routhian surface (TRS) approach.Production cross sections of superheavy nuclei:The synthesis mechanism of superheavy elements has been investigated systematically within the DNS concept, where the master equation is solved numerically to obtain the fusion probability. The competition between complete fusion and quasifission, which can strongly affect the cross section of the compound nucleus formation, is taken into account. The calculated evaporation residue cross section crER is related to the three stages (capture, fusion and evaporation) in the process of the formation of superheavy elements. The crER values for the superheavy elements up to Z=l18are calculated with208Pb-and actinide-based targets in the cold and hot fusion reactions, respectively. The effects of isospin, inner fusion barrier, neutron separation energy and fission barrier on the production cross sections are studied. Our theoretical calculations are basically in agreement with the known experimental data. Further, production cross sections for superheavy nuclei with Z=119-121are studied systematically. The results indicate that their production cross sections are relatively small, especially for the58Fe+243Amâ†'301121reaction. It is also found that the cross sections for the production of elements119and121using the reaction systems 48Ca+254Es and50Ti+254Es are larger than those using the systems mentioned above, but it is rather difficult to accumulate the required amount of254Es to prepare a target.Rotational properties of nobelium isotopes:The rotational properties of the synthesized even-even248"264No isotopes have been investigated by means of total Routhian surface calculations. The calculated ground-state properties β2,β4are in agreement with previously published results. The behaviors of moment of inertia of252,254No are well reproduced by our calculations. The systematic upbending in moment of inertia is attributed to band crossing. It is found that the j15/2neutron rotation-alignment is preferred for the lighter No isotopes, but the i13/2proton alignment is favored in the heavier ones.