N. V. Antonenko

Effective nucleus-nucleus potential for calculation of potential energy of a dinuclear system

An effective method to calculate the potential energy of a dinuclear system is suggested. The nuclear part of the nucleus-nucleus potential is taken in the double folding form. The analytical expressions obtained allow one to simplify the calculations of interaction between two nuclei except the nuclei near the drip lines. The relationship between the double folding potential and the proximity potential is found. The influence of a deformation and a relative orientation of nuclei on the interaction potential is investigated. The method is applied to the calculations of the energies of the dinuclear and trinuclear systems.

Mass parameters for a dinuclear system

Abstract A microscopical method is proposed to derive the diagonal and nondiagonal components of the inertia tensor for a dinuclear system formed in the heavy-ion collision at low energy. The coupling between different modes of motion for the various mass asymmetries and fragment separations is analyzed. The definition of a neck parameter for a dinuclear system is proposed. It is shown that the coupling of the radial and mass-asymmetry modes is weak for almost symmetric configuration but it enhances significantly as the asymmetry increases.

Peculiarities of the sub-barrier fusion with the quantum diffusion approach

Abstract.With the quantum diffusion approach the unexpected behavior of the fusion cross-section, angular momentum, and astrophysical S -factor at sub-barrier energies has been revealed. Out of the region of short-range nuclear interaction and action of friction at the turning point the decrease rate of the cross-section under the barrier becomes smaller. The calculated results for the reactions with spherical nuclei are in a good agreement with the existing experimental data.

Effects of nuclear deformation and neutron transfer in capture process, and origin of fusion hindrance at deep sub-barrier energies

The roles of nuclear deformation and neutron transfer in sub-barrier capture process are studied within the quantum diffusion approach. The change of the deformations of colliding nuclei with neutron exchange can crucially influence the sub-barrier fusion. The comparison of the calculated capture cross section and the measured fusion cross section in various reactions at extreme subbarrier energies gives us information about the fusion and quasifission.

Quantum statistical effects in nuclear reactions, fission, and open quantum systems

Quantum diffusion equations with time-dependent transport coefficients are derived from generalized non-Markovian Langevin equations. Generalized fluctuation-dissipation relations and analytical formulas for calculating friction and diffusion coefficients in nuclear processes are obtained. The asymptotics of the transport coefficients and of the correlation functions are investigated. The problem of correlation decay in quantum dissipative systems is studied. A comparative analysis of diffusion coefficients for the harmonic and inverted oscillators is performed. The role of quantum statistical effects during passage through a parabolic potential barrier is investigated. Sets of diffusion coefficient assuring the purity of states at any time instant are found in cases of non-Markovian dynamics. The influence of different sets of transport coefficients on the rate of decay from a metastable state is studied in the framework of the master equation for reduced density matrices describing open quantum systems. The approach developed is applied to investigation of fission processes and the processes of projectile-nuclei capture by target nuclei for bombarding energies in the vicinity of the Coulomb barrier. The influence of dissipation and fluctuation on these processes is taken into account in a self-consistent way. The evaporation residue cross sections for asymmetric fusion reactions are calculated from the derived capture probabilities averaged over all orientations of the deformed projectile and target nuclei.

Application of statistical methods for analysis of heavy-ion reactions in the framework of a dinuclear system model

Heavy-ion reactions are investigated by statistical methods in the framework of a dinuclear system model (DNS). Synthesis of superheavy elements in cold and hot fusion reactions on Pb and Bi targets, as well as in incomplete fusion reactions, is considered. We also take a look at production of neutron-deficient isotopes and pre-scission neutron emission in quasifission reactions. The results of calculations are compared with the available experimental data. The sensitivity of these results to the method of calculation of the level density and to various theoretical predictions of nuclear properties is analyzed.

Microscopic driving potential for a dinuclear system

Abstract The stationary solution of the master equation with the microscopically calculated transport coefficients is used to obtain the iteration procedure for the reconstruction of the driving potential. The calculated results have demonstrated a surprising similarity of the microscopic and phenomeno-logical driving potentials. This is the argument for the validity of the microscopic approach.

Neutron-pair transfer in the sub-barrier capture process

The sub-barrier capture reactions following the neutron pair transfer are proposed to be used for the indirect study of neutron-neutron correlation in the surface region of nucleus. The strong effect of the dineutron-like clusters transfer stemming from the surface of magic and non-magic nuclei

Mass distributions for induced fission of different Hg isotopes

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Cluster approach to description of fission modes

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