4,231 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
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
Infrared singularities in Landau gauge Yang-Mills theory
We present a more detailed picture of the infrared regime of Landau gauge
Yang-Mills theory. This is done within a novel framework that allows one to
take into account the influence of finite scales within an infrared power
counting analysis. We find that there are two qualitatively different infrared
fixed points of the full system of Dyson-Schwinger equations. The first extends
the known scaling solution, where the ghost dynamics is dominant and gluon
propagation is strongly suppressed. It features in addition to the strong
divergences of gluonic vertex functions in the previously considered uniform
scaling limit, when all external momenta tend to zero, also weaker kinematic
divergences, when only some of the external momenta vanish. The second solution
represents the recently proposed decoupling scenario where the gluons become
massive and the ghosts remain bare. In this case we find that none of the
vertex functions is enhanced, so that the infrared dynamics is entirely
suppressed. Our analysis also provides a strict argument why the Landau gauge
gluon dressing function cannot be infrared divergent.Comment: 29 pages, 25 figures; published versio
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
Attachment working models as unconscious structures: An experimental test
Internal working models of attachment (IWMs) are presumed to be largely unconscious representations of childhood attachment experiences. Several instruments have been developed to assess IWMs; some of them are based on self-report and others on narrative interview techniques. This study investigated the capacity of a self-report measure, the Inventory of Parent and Peer Attachment (IPPA; Armsden & Greenberg, 1987), and of a narrative interview method, the Adult Attachment Interview (AAI; George, Kaplan, & Main, 1985), to measure unconscious attachment models. We compared scores on the two attachment instruments to response latencies in an attachment priming task. It was shown that attachment organisation assessed by the AAI correlates with priming effects, whereas the IPPA scales were inversely or not related to priming. The results are interpreted as support for the assumption that the AAI assesses, to a certain degree, unconscious working models of attachment
Study of the stability of the S-IC open-loop propellant-hydraulic system Final report, Jul. 26, 1964 - Jul. 26, 1966
Saturn S-IC open-loop propellant-hydraulic system stud
Conservation Properties in the Time-Dependent Hartree Fock Theory
We discuss the conservation of angular momentum in nuclear time-dependent
Hartree-Fock calculations for a numerical representation of wave functions and
potentials on a three-dimensional cartesian grid. Free rotation of a deformed
nucleus performs extremely well even for relatively coarse spatial grids. Heavy
ion collisions produce a highly excited compound system associated with
substantial nucleon emission. These emitted nucleons reach the bounds of the
numerical box which leads to a decrease of angular momentum. We discuss
strategies to distinguish the physically justified loss from numerical
artifacts.Comment: 4 page
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