Friction Coefficient for Deep-Inelastic Heavy-Ion Collisions

Based on the microscopic model, the friction coefficient for the relative motion of nuclei in deep-inelastic heavy-ion collisions is calculated. The radial dependence of the friction coefficient is studied and the results are compared with those found by other methods. Based on this result, it was demonstrated that the kinetic energy dissipation in deep-inelastic heavy-ion collisions is a gradual process which takes up a significant part of a reaction time. An advantage of the suggested method is that it allows one to consider the relative motion of nuclei and the intrinsic motion self-consistently.Comment: 15 pages, RevTex, 7 Postscript figures, submitted to Phys. Rev.

Emission of charged particles from excited compound nuclei

The formation of excited compound nucleus (CN) and its statistical decay is investigated within the dinuclear system (DNS) model.The initial DNS is formed in the entrance channel when the projectile is captured by a target, and then the evolution of DNS in mass asymmetry coordinate leads to formation of the hot CN. The emission barriers for complex fragments were calculated within the DNS model by using the double folding procedure for the interaction potential. It is shown that cross sections for complex fragment emission become larger when excited CN is more neutron deficient. This approach gives also an opportunity to calculate the new neutron deficient isotopes production cross sections and can be applied to describe the hot fission of heavy systems.The model was tested by comparison of calculated results with experimental dat

Production of exotic isotopes in complete fusion reactions with radioactive beams

The isotopic dependence of the complete fusion (capture) cross section is analyzed in the reactions $^{130,132,134,136,138,140,142,144,146,148,150}$Xe+$^{48}$Ca with stable and radioactive beams. It is shown for the first time that the very neutron-rich nuclei $^{186-191}$W can be reached with relatively large cross sections by complete fusion reactions with radioactive ion beams at incident energies near the Coulomb barrier. A comparison between the complete fusion and fragmentation reactions for the production of neutron-rich W and neutron-deficient Rn isotopes is performed.Comment: 13 pages, 6 figures, accepted in PR

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 sub- barrier energies gives us information about the fusion and quasifission.Comment: 11 pages, 19 figures, submitted to Phys.Rev.

Effects of the entrance channel and fission barrier in synthesis of superheavy element ZZ=120

The fusion and evaporation residue cross sections for the $^{50}$Ti+$^{249}$Cf and $^{54}$Cr+$^{248}$Cm reactions calculated by the combined dinuclear system and advanced statistical models are compared. These reactions are considered to be used to synthesize the heaviest superheavy element. The $^{50}$Ti+$^{249}$Cf reaction is more mass asymmetric than $^{54}$Cr+$^{248}$Cm and the fusion excitation function for the former reaction is higher than the one for the latter reaction. The evaporation residue excitation functions for the mass asymmetric reaction is higher in comparison with the one of the $^{54}$Cr+$^{248}$Cm reaction. The use of the mass values of superheavy nuclei calculated in the framework of the macroscopic-microscopic model by the Warsaw group leads to smaller evaporation residue cross section for both the reactions in comparison with the case of using the masses calculated by Peter M\"oller {\it et al}. The $^{50}$Ti+$^{249}$Cf reaction is more favorable in comparison with the $^{54}$Cr+$^{248}$Cm reaction: the maximum values of the excitation function of the 3n-channel of the evaporation residue formation for the $^{50}$Ti+$^{249}$Cf and $^{54}$Cr+$^{248}$Cm reactions are about 0.1 and 0.07 pb, respectively, but the yield of the 4n-channel for the former reaction is lower (0.004 pb) in comparison with the one (0.01 pb) for the latter reaction.Comment: 21 pages, 10 figures, 2 table

Measurement of the Cross Section Asymmetry of the Reaction gp-->pi0p in the Resonance Energy Region Eg = 0.5 - 1.1 GeV

The cross section asymmetry Sigma has been measured for the photoproduction of pi0-mesons off protons, using polarized photons in the energy range Eg = 0.5 - 1.1 GeV. The CM angular coverage is Theta = 85 - 125 deg with energy and angle steps of 25 MeV and 5 deg, respectively. The obtained Sigma data, which cover the second and third resonance regions, are compared with existing experimental data and recent phenomenological analyses. The influence of these measurements on such analyses is also considered

Fluctuation-enhanced gas sensing

AbstractThe sensitivity of gas sensors was earlier measured by classical method-comparison the resistance of sensors in gas media and air. Here we reported results of the study of low-frequency noise characteristics of sensors. We compare data for different Figaro TGS sensors as well as our sol-gel H2 tin dioxide and porous silicon sensors. The study was performed in dry air and in a mix of dry air with carbon monoxide, hydrogen and alcohol of different concentrations. Higher sensitivity of spectral dependence of noise (SDN) to gas concentration in comparison with classical method of the measurements of gas sensing by a change in the Ohmic resistance part of current-voltage characteristics of samples allows using such SND powerful method for determination of gas concentration in the air or environment