235 research outputs found
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
Xe+Ca with stable and
radioactive beams. It is shown for the first time that the very neutron-rich
nuclei 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 =120
The fusion and evaporation residue cross sections for the
Ti+Cf and Cr+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 Ti+Cf reaction is more mass asymmetric than
Cr+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 Cr+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 Ti+Cf reaction is
more favorable in comparison with the Cr+Cm reaction: the
maximum values of the excitation function of the 3n-channel of the evaporation
residue formation for the Ti+Cf and Cr+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
- …