80 research outputs found
Microscopic Description of Nuclear Fission Dynamics
We discuss possible avenues to study fission dynamics starting from a
time-dependent mean-field approach. Previous attempts to study fission dynamics
using the time-dependent Hartree-Fock (TDHF) theory are analyzed. We argue that
different initial conditions may be needed to describe fission dynamics
depending on the specifics of the fission phenomenon and propose various
approaches towards this goal. In particular, we provide preliminary
calculations for studying fission following a heavy-ion reaction using TDHF
with a density contraint. Regarding prompt muon-induced fission, we also
suggest a new approach for combining the time-evolution of the muonic wave
function with a microscopic treatment of fission dynamics via TDHF
Microscopic Description of Nuclear Fission Dynamics
We discuss possible avenues to study fission dynamics starting from a
time-dependent mean-field approach. Previous attempts to study fission dynamics
using the time-dependent Hartree-Fock (TDHF) theory are analyzed. We argue that
different initial conditions may be needed to describe fission dynamics
depending on the specifics of the fission phenomenon and propose various
approaches towards this goal. In particular, we provide preliminary
calculations for studying fission following a heavy-ion reaction using TDHF
with a density contraint. Regarding prompt muon-induced fission, we also
suggest a new approach for combining the time-evolution of the muonic wave
function with a microscopic treatment of fission dynamics via TDHF
Localization in light nuclei
We investigate the presence of spatial localization in nuclei using a method
that maps the nucleon same-spin pair probability and is based on the
density-matrix. The method is used to study spatial localization of light
nuclei within the Hartree-Fock approximation. We show that the method provides
an alternative tool for studying spatial localization in comparison to the
localization observed from maxima in the nuclear mass density.Comment: 6 pages, 5 figure
Entrance Channel Dynamics of Hot and Cold Fusion Reactions Leading to Superheavy Elements
We investigate the entrance channel dynamics for the reactions
and
using the fully microscopic time-dependent Hartree-Fock (TDHF) theory coupled
with a density constraint. We calculate excitation energies and capture
cross-sections relevant for the study of superheavy formations. We discuss the
deformation dependence of the ion-ion potential for the
system and perform an alignment angle
averaging for the calculation of the capture cross-section. The results show
that this parameter-free approach can generate results in good agreement with
experiment and other theories
Fusion using time-dependent density-constrained DFT
We present results for calculating fusion cross-sections using a new
microscopic approach based on a time-dependent density-constrained DFT
calculations. The theory is implemented by using densities and other
information obtained from TDDFT time-evolution of the nuclear system as
constraint on the density for DFT calculations.Comment: 4 Pages, 6 Figures Proceedings of INPC 2013, to be published in EPJ
Web of Conference
Microscopic sub-barrier fusion calculations for the neutron star crust
Fusion of very neutron rich nuclei may be important to determine the
composition and heating of the crust of accreting neutron stars. Fusion cross
sections are calculated using time-dependent Hartree-Fock theory coupled with
density-constrained Hartree-Fock calculations to deduce an effective potential.
Systems studied include 16O+16O, 16O+24O, 24O+24O, 12C+16O, and 12C+24O. We
find remarkable agreement with experimental cross sections for the fusion of
stable nuclei. Our simulations use the SLy4 Skyrme force that has been
previously fit to the properties of stable nuclei, and no parameters have been
fit to fusion data. We compare our results to the simple S\~{a}o Paulo static
barrier penetration model. For the asymmetric systems 12C+24O or 16O+24O we
predict an order of magnitude larger cross section than those predicted by the
S\~{a}o Paulo model. This is likely due to the transfer of neutrons from the
very neutron rich nucleus to the stable nucleus and dynamical rearrangements of
the nuclear densities during the collision process. These effects are not
included in potential models. This enhancement of fusion cross sections, for
very neutron rich nuclei, can be tested in the laboratory with radioactive
beams.Comment: 9 pages, 11 figures, corrected small errors in Figs 10, 11, Phys.
Rev. C in pres
Single-particle dissipation in TDHF studied from a phase-space perspective
We study dissipation and relaxation processes within the time-dependent
Hartree-Fock approach using the Wigner distribution function. On the technical
side we present a geometrically unrestricted framework which allows us to
calculate the full six-dimensional Wigner distribution function. With the
removal of geometrical constraints, we are now able to extend our previous
phase-space analysis of heavy-ion collisions in the reaction plane to
unrestricted mean-field simulations of nuclear matter on a three-dimensional
Cartesian lattice. From the physical point of view we provide a quantitative
analysis on the stopping power in TDHF. This is linked to the effect of
transparency. For the medium-heavy Ca+Ca system we examine the
impact of different parametrizations of the Skyrme force, energy-dependence,
and the significance of extra time-odd terms in the Skyrme functional.Comment: 7 pages, 4 figures, 2 videos. arXiv admin note: substantial text
overlap with arXiv:1201.526
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