Phase Space Representation for Open Quantum Systems within the Lindblad Theory

The Lindblad master equation for an open quantum system with a Hamiltonian containing an arbitrary potential is written as an equation for the Wigner distribution function in the phase space representation. The time derivative of this function is given by a sum of three parts: the classical one, the quantum corrections and the contribution due to the opening of the system. In the particular case of a harmonic oscillator, quantum corrections do not exist.Comment: 19 pages, Latex, accepted for publication in Int. J. Mod. Phys.

Inverse Scattering by the Stability Index Method

A novel numerical method for solving inverse scattering problem with fixed-energy data is proposed. The method contains a new important concept: the stability index of the inversion problem. This is a number, computed from the data, which shows how stable the inversion is. If this index is small, then the inversion provides a set of potentials which differ so little, that practically one can represent this set by one potential. If this index is larger than some threshold, then practically one concludes that with the given data the inversion is unstable and the potential cannot be identified uniquely from the data. Inversion of the fixed-energy phase shifts for several model potentials is considered. The results show practical efficiency of the proposed method. The method is of general nature and is applicable to a very wide variety of the inverse problems

Systematics of fusion probability in "hot" fusion reactions

The fusion probability in "hot" fusion reactions leading to the synthesis of super-heavy nuclei is investigated systematically. The quasi-fission barrier influences the formation of the super-heavy nucleus around the "island of stability" in addition to the shell correction. Based on the quasi-fission barrier height obtained with the Skyrme energy-density functional, we propose an analytical expression for the description of the fusion probability, with which the measured evaporation residual cross sections can be reproduced acceptably well. Simultaneously, some special fusion reactions for synthesizing new elements 119 and 120 are studied. The predicted evaporation residual cross sections for 50Ti+249Bk are about 10-150fb at energies around the entrance-channel Coulomb barrier. For the fusion reactions synthesizing element 120 with projectiles 54Cr and 58Fe, the cross sections fall to a few femtobarns which seems beyond the limit of the available facilities.Comment: 5 figures, 1 tabl

Dynamics of dinuclear system formation and its decay in heavy ion collisions

A variety of phenomena connected with the formation of a dinuclear complex is observed in the heavy ion collisions at low energies. The dinuclear system model allows us to analyze the experimental data and to interpret them by comparison of the partial capture, fusion and evaporation residue cross sections measured for the different reactions leading to the same compound nucleus. The comparison of theoretical and experimental values of the mass and angular distributions of the reaction products gives us a detailed information about reaction mechanism forming the observed yields. The observed very small cross sections of the evaporation residues may be explained by the strong fusion hindrance and/or instability of the heated and rotating compound nucleus and smallness of its survival probability. The fusion hindrance arises due to competition between complete fusion and quasifission while the smallness of survival probability is connected with the decrease of the fission barrier at large excitation energy and angular momentum of compound nucleus.Comment: 20 pages, 16 figures, Contribution to the International Symposium on Quasifission Process in Heavy Ion Reactions, 8-9 November, 2010, Messina, Ital

Search of systematic behavior of breakup probability in reactions with weakly bound projectiles at energies around Coulomb barrier

Comparing the capture cross sections calculated without the breakup effect and experimental complete fusion cross sections, the breakup was analyzed in reactions with weakly bound projectiles $^{6,7,9}$Li, $^{9,11}$Be, and $^{6,8}$He. A trend of a systematic behavior for the complete fusion suppression as a function of the target charge and bombarding energy is not achieved. The quasielastic backscattering is suggested to be an useful tool to study the behavior of the breakup probability in reactions with weakly bound projectiles.Comment: 15 pages, 15 figures, accepted in PR