151 research outputs found
Multi-Nucleon Exchange in Quasi-Fission Reactions
Nucleon exchange mechanism is investigated in the central collisions of
Ca + U and Ca + U systems near the
quasi-fission regime in the framework of the Stochastic Mean-Field (SMF)
approach. Sufficiently below the fusion barrier, di-nuclear structure in the
collisions is maintained to a large extend. Consequently, it is possible to
describe nucleon exchange as a diffusion process familiar from deep-inelastic
collisions. Diffusion coefficients for proton and neutron exchange are
determined from the microscopic basis of the SMF approach in the semi-classical
framework. Calculations show that after a fast charge equilibration the system
drifts toward symmetry over a very long interaction time. Large dispersions of
proton and neutron distributions of the produced fragments indicate that
diffusion mechanism may help to populate heavy trans-uranium elements near the
quasi-fission regime in these collisions
Nucleon exchange in heavy-ion collisions within stochastic mean-field approach
Nucleon exchange mechanism is investigated in deep-inelastic symmetric
heavy-ion collisions in the basis of the Stochastic Mean-Field approach. By
extending the previous work to off-central collisions, analytical expression is
deduced for diffusion coefficient of nucleon exchange mechanism. Numerical
calculations are carried out for Ca + Ca and Zr +
Zr systems and the results are compared with the phenomenological
nucleon exchange model. Also, calculations are compared with the available
experimental results of deep-inelastic collisions between calcium nuclei.Comment: 8 pages, 7 figure
Collisional Damping of Nuclear Collective Vibrations in a Non-Markovian Transport Approach
A detailed derivation of the collisional widths of collective vibrations is
presented in both quantal and semi-classical frameworks by considering the
linearized limits of the extended TDHF and the BUU model with a non-Markovian
binary collision term. Damping widths of giant dipole and giant quadrupole
excitations are calculated by employing an effective Skyrme force, and the
results are compared with GDR measurements in Lead and Tin nuclei at finite
temperature.Comment: 23 pages, 6 Figure
Isovector Collective Response Function of Nuclear Matter at Finite Temperature
We study isovector collective excitations in nuclear matter by employing the
linearized Landau-Vlasov equation with and without a non-Markovian binary
collision term at finite temperature. We calculate the giant dipole resonance
(GDR) strength function for finite nuclei using Steinwedel-Jensen model and
also by Thomas-Fermi approximation, and we compare them for 120Sn and 208Pb
with experimental results.Comment: 15 pages, 4 figure
Quantal description of nucleon exchange in stochastic mean-field approach
Nucleon exchange mechanism is investigated in central collisions of symmetric
heavy-ions in the basis of the stochastic mean-field approach. Quantal
diffusion coefficients for nucleon exchange are calculated by including
non-Markovian effects and shell structure. Variances of fragment mass
distributions are calculated in central collisions of Ca +
Ca, Ca + Ca and Ni + Ni systems
Quantum effects in the diffusion process to form a heavy nucleus in heavy-ion fusion reactions
We discuss quantum effects in the diffusion process which is used to describe the shape evolution from the touching configuration of fusing two nuclei to a compound nucleus. Applying the theory with quantum effects to the case where the potential field, the mass and friction parameters are adapted to realistic values of heavy-ion collisions, we show that the quantum effects play significant roles at low temperatures which are relevant to the synthesis of superheavy elements
Merging of transport theory with TDHF: multinucleon transfer in U+U collisions
Multinucleon transfer mechanism in the collision of
system is investigated at MeV in the framework of the quantal diffusion description based on the
stochastic mean-field approach (SMF). Double cross-sections as a
function of the neutron and proton numbers, the cross-sections and
as a function of the atomic numbers and the mass numbers are
calculated for production of the primary fragments. The calculation indicates
the system may be located at an unstable
equilibrium state at the potential energy surface with a slightly negative
curvature along the beta stability line on the plane. This behavior may
lead to rather large diffusion along the beta stability direction.Comment: 10 pages, 10 figures. arXiv admin note: text overlap with
arXiv:1904.0961
Heavy isotope production in collisions at MeV
Employing the quantal diffusion mechanism for multi-nucleon transfer, the
double differential cross-sections are calculated for production of primary
projectile-like and target-like fragments in collisions of
system at MeV.
Including de-excitation due to neutron emission, the cross-section for
production of , and
isotopes are estimated and compared with data.Comment: 7 pages, 3 figures, 2 table
Quantal Diffusion Description of Multi-Nucleon Transfers in Heavy-Ion Collisions
Employing the stochastic mean-field (SMF) approach, we develop a quantal
diffusion description of the multi-nucleon transfer in heavy-ion collisions at
finite impact parameters. The quantal transport coefficients are determined by
the occupied single-particle wave functions of the time-dependent Hartree-Fock
equations. As a result, the primary fragment mass and charge distribution
functions are determined entirely in terms of the mean-field properties. This
powerful description does not involve any adjustable parameter, includes the
effects of shell structure and is consistent with the fluctuation-dissipation
theorem of the non-equilibrium statistical mechanics. As a first application of
the approach, we analyze the fragment mass distribution in
collisions at the bombarding energy
MeV and compare the calculations with the experimental
data.Comment: 15 pages, 8 figures, 2 tables. arXiv admin note: text overlap with
arXiv:1706.0356
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