18,589 research outputs found
Mass distributions in a variational model
The time-dependent Hartree-Fock approach may be derived from a variational
principle and a Slater Determinant wavefunction Ansatz. It gives a good
description of nuclear processes in which one-body collisions dominate and has
been applied with success to giant resonances and collisions around the
barrier. It is inherently unable to give a good description of two-body
observables. A variational principle, due to Balian and Veneroni has been
proposed which can be geared to good reproduction of two-body observables.
Keeping the Slater Determinant Ansatz, and restricting the two-body observables
to be the squares of one-body observables, the procedure can be implemented as
a modification of the time-dependent Hartree-Fock procedure. Applications,
using the Skyrme effective interaction, are presented for the mass
distributions of fragments following de-excitation of the giant dipole
resonance in S-32. An illustration of the method's use in collisions is given.Comment: 5 pages, proceedings of XXXII Symposium on Nuclear Physics, Cocoyoc,
Mexic
Cause of the charge radius isotope shift at the \emph{N}=126 shell gap
We discuss the mechanism causing the `kink' in the charge radius isotope
shift at the N=126 shell closure. The occupation of the 1 neutron
orbital is the decisive factor for reproducing the experimentally observed
kink. We investigate whether this orbital is occupied or not by different
Skyrme effective interactions as neutrons are added above the shell closure.
Our results demonstrate that several factors can cause an appreciable
occupation of the 1 neutron orbital, including the magnitude of the
spin-orbit field, and the isoscalar effective mass of the Skyrme interaction.
The symmetry energy of the effective interaction has little influence upon its
ability to reproduce the kink.Comment: 4 pages, 4 figures, to be submitted to proceedings of INPC 201
Shapes and Dynamics from the Time-Dependent Mean Field
Explaining observed properties in terms of underlying shape degrees of
freedom is a well--established prism with which to understand atomic nuclei.
Self--consistent mean--field models provide one tool to understand nuclear
shapes, and their link to other nuclear properties and observables. We present
examples of how the time--dependent extension of the mean--field approach can
be used in particular to shed light on nuclear shape properties, particularly
looking at the giant resonances built on deformed nuclear ground states, and at
dynamics in highly-deformed fission isomers. Example calculations are shown of
Si in the first case, and Pu in the latter case.Comment: 9 pages, 5 figures, to appear in proceedings of International
Workshop "Shapes and Dynamics of Atomic Nuclei: Contemporary Aspects"
(SDANCA-15), 8-10 October 2015, Sofia, Bulgari
Development of anlytical techniques for hydrocarbons in mineral aggregates quarterly status report no. 4, jul. - sep. 1964
Chemical analysis of rock and meteorite samples for hydrocarbon conten
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