N. V. Antonenko

Fusion cross sections for superheavy nuclei in the dinuclear system concept

Abstract Using the dinuclear system concept we present calculations of production cross sections for the heaviest nuclei. The obtained results are in a good agreement with the experimental data. The experimentally observed rapid fall-off of the cross sections of the cold fusion with increasing charge number Z of the compound nucleus is explained. Optimal reactions for the synthesis of the superheavy nuclei are suggested.Using the dinuclear system concept we present calculations of production cross sections for the heaviest nuclei. The obtained results are in a good agreement with the experimental data. The experimentally observed rapid fall-off of the cross sections of the cold fusion with increasing charge number

Isotopic dependence of fusion cross sections in reactions with heavy nuclei

Z

Relationship between dinuclear systems and nuclei in highly deformed states

of the compound nucleus is explained. Optimal experimental conditions for the synthesis of the superheavy nuclei are suggested.

Problems in description of fusion of heavy nuclei in the two-center shell model approach

Abstract The dependence of fusion cross section on the isotopic composition of colliding nuclei is analysed within the dinuclear system concept for compound nucleus formation. Probabilities of fusion and surviving probabilities, ingredients of the evaporation residue cross sections, depend decisively on the neutron numbers of the dinuclear system. Evaporation residue cross sections for the production of actinides and superheavy nuclei, listed in table form, are discussed and compared with existing experimental data. In the Pb-based reactions neutron-rich radioactive projectiles are shown to lead to similar fusion cross sections as stable projectiles.The dependence of fusion cross section on the isotopic composition of colliding nuclei is analysed within the dinuclear system concept for compound nucleus formation. Probabilities of fusion and surviving probabilities, ingredients of the evaporation residue cross sections, depend decisively on the neutron numbers of the dinuclear system. Evaporation residue cross sections for the production of actinides and superheavy nuclei, listed in table form, are discussed and compared with existing experimental data. Neutron-rich radioactive projectiles are shown to lead to similar fusion cross sections as stable projectiles.

Cluster interpretation of properties of alternating parity bands in heavy nuclei

Potential energies, moments of inertia, quadrupole and octupole moments of dinuclear systems are compared with the corresponding quantities of strongly deformed nuclei. As dinuclear system we denote two touching nuclei (clusters). It is found that the hyperdeformed states of nuclei are close to those of nearly symmetric dinuclear systems, whereas the superdeformed states are considered as states of asymmetric dinuclear systems. The superdeformed and hyperdeformed states constructed from two touching clusters have large octupole deformations. The experimental measurement of octupole deformation of the highly deformed nuclei can answer whether these nuclei have cluster configurations as described by the dinuclear model.Potential energies, moments of inertia, quadrupole and octupole moments of dinuclear systems are compared with the corresponding quantities of strongly deformed nuclei. As dinuclear system we denote two touching nuclei (clusters). It is found that the hyperdeformed states of nuclei are close to those of nearly symmetric dinuclear systems, whereas the superdeformed states are considered as states of asymmetric dinuclear systems. The superdeformed and hyperdeformed states constructed from two touching clusters have large octupole deformations. The experimental measurement of octupole deformation of the highly deformed nuclei can answer whether these nuclei have cluster configurations as described by the dinuclear model.

Cluster interpretation of parity splitting in alternating parity bands

Abstract Within the two-center shell model, the following description of complete fusion of heavy nuclei is considered. With growing neck the system rapidly falls to the fission-type valley and then the fusion occurs due to diffusion of the system in this valley to smaller elongations. The fusion probabilities obtained in this model are much larger than the values found from the experimental data. In order to describe the experimental data on the fusion of heavy nuclei, we should assume a hindrance for the fast growth of the neck and for the motion to smaller elongations of the system. The mechanisms for these hindrances are discussed. By using mass parameters calculated microscopically, the system lives a sufficiently long time in dinuclear system configuration in order to evolve in the mass asymmetry for fusion.

Dinuclear system in diabatic two-center shell model approach

The properties of the states of the alternating parity bands in actinides, Ba, Ce and Nd isotopes are analyzed within a cluster model. The model is based on the assumption that cluster type shapes are produced by the collective motion of the nuclear system in the mass asymmetry coordinate. The calculated spin dependences of the parity splitting and of the electric multipole transition moments are in agreement with the experimental data.

Melting or nucleon transfer in fusion of heavy nuclei

The parity splitting in actinides is described with a cluster model of oscillations in mass asymmetry coordinate. The spin dependence of the calculated parity splitting is in a good agreement with the experimental data.

TUNNELING WITH DISSIPATION IN OPEN QUANTUM SYSTEMS

Abstract Diabatic potentials as a function of the elongation and neck parameter for various symmetric heavy-ion systems are studied within the generalized two-center shell model. In the calculations the maximum symmetry method is applied. The diabatic potentials show hindrances for the motion to a smaller relative distance and for the growth of the neck. They are similar to nucleus-nucleus potentials used in the dinuclear system model of fusion which is able to describe the experimental data. The dependence of the diabatic potential on temperature and mass asymmetry is discussed.

Potential in mass asymmetry and quasifission in a dinuclear system

Abstract The time-dependent transition between a diabatic interaction potential in the entrance channel and an adiabatic potential during the fusion process is investigated within the two-center shell model. A large hindrance is obtained for the motion to smaller elongations of near symmetric dinuclear systems. The comparison of the calculated energy thresholds for the complete fusion in different relevant collective variables shows that the dinuclear system prefers to evolve in the mass asymmetry coordinate by nucleon transfer to the compound nucleus.The time-dependent transition between a diabatic interaction potential in the entrance channel and an adiabatic potential during the fusion process is investigated within the two-center shell model. A large hindrance is obtained for the motion to smaller elongations of near symmetric dinuclear systems. The comparison of the calculated energy thresholds for the complete fusion in different relevant collective variables shows that the dinuclear system prefers to evolve in the mass asymmetry coordinate by nucleon transfer to the compound nucleus.