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Excitation functions have been measured for evaporation residues from compound nuclei formed in the interaction of 6He with 197Au and 206Pb. The transfer reactions leading to 194Au, 196Au and 198Au were also studied for the case of 6He + 197Au. The experiments were performed at the JINR accelerator complex for radioactive beams DRIBs, capable of providing 6He beams of about 10 AMeV maximum energy and an intensity of up to 2×107 pps. The stacked foil activation technique was used directly in the beam extracted from the cyclotron or in the focal plane of the magnetic spectrometer MSP-144. The identification of the reaction products was done by their radioactive γ- or α-decay. The fusion reactions with the evaporation of two neutrons were characterized by an increase in the cross section compared to statistical model calculations. The analysis of the data in the framework of the statistical model for the decay of excited nuclei when the sequential fusion of 6He was taken into account has shown good agreement between the experimental and the calculated values of the cross sections for the case of sub-Coulomb-barrier fusion in the 206Pb+6He reaction. At the Coulomb barrier unusually high cross section was measured for the production of 198Au, whereas only an upper limit was determined for the formation of 199Au. Possible mechanisms of formation and decay of transfer reaction products are discussed. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Excitation functions have been measured for the fusion reaction 197Au(αxn)201-xnTl with the evaporation of x neutrons (0<=x<=3) in the energy range 14–36 MeV. The induced-activation method was used for registration and identification of the reaction products. The experimental cross sections for the (1–3)-neutron evaporation residues are in good agreement with the results known from literature. For the radiation capture reaction 197Au(α,γ)201Tl, the upper limit was obtained essentially lower. The excitation functions for the measured reactions are compared with calculations in the frame of the statistical model, as well as with formerly measured similar data with a 6He beam. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The existing and some preliminary experimental data on the total cross sections of the 4,6He, 6,7Li+28Si reactions at energies E=5–50 A MeV are demonstrated. The data on 6Li,6He+28Si are analyzed in the framework of the microscopic optical potential with real and imaginary parts obtained with a help of the double-folding procedure and by using the current models of densities of the projectile nuclei. Besides, the microscopic double-folding Coulomb potential is calculated and its effect on cross sections is compared with that when one applies the traditional Coulomb potential of the uniform charge distribution. The semi-microscopic potentials are constructed from both the renormalized microscopic potentials and their derivatives to take into account collective motion effect and to improve an agreement with experimental data. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]