14,964 research outputs found
As-built design specification of the data order processor ORDHDT
A description and subroutine documentation of the data order processor, ORHDT is given. As part of the LANDSAT imagery verification and extraction system, ORDHT creates a computer tape containing the AgRISTARS requirements for LANDSAT data to be ordered from Goddard Space Flight Center. A brief description of hardware requirements is also included
Isovector properties of the Gogny interaction
We analyse the properties of the Gogny interaction in homogeneous matter,
with special emphasis on the isovector sector. We provide analytical
expressions for both the single-particle and the bulk properties of symmetric
and asymmetric nuclear matter. We perform an extensive analysis of these
properties using 11 parametrizations extracted from the literature. We find
that most Gogny interactions have low values for the slope of the symmetry
energy, outside the range of empirically extracted values. As a test of extreme
isospin dependence, we also study the mass-radius relations implied by the
different Gogny equations of state. Our results call for a more careful fitting
procedure of the isovector properties of Gogny functionals.Comment: 23 pages, 14 figures, 1 table. Final published version, typos
correcte
Density and isospin asymmetry dependence of high-momentum components
We study the one-body momentum distribution at different densities in nuclear
matter, with special emphasis on its components at high momentum. Explicit
calculations for finite neutron-proton asymmetry, based on the ladder
self-consistent Green's function approach, allow us to access the isospin
dependence of momentum distributions and elucidate their role in neutron-rich
systems. Comparisons with the deuteron momentum distribution indicate that a
substantial proportion of high-momentum components are dominated by tensor
correlations. We identify the density dependence of these tensor correlations
in the momentum distributions. Further, we find that high-momentum components
are determined by the density of each sub-species and we provide a new isospin
asymmetry scaling of these components. We use different realistic
nucleon-nucleon interactions to quantify the model dependence of our results.Comment: 14 pages, 7 figures, 1 table. Accepted version in Phys. Rev.
Pairing and short-range correlations in nuclear systems
The structure and density dependence of the pairing gap in infinite matter is
relevant for astrophysical phenomena and provides a starting point for the
discussion of pairing properties in nuclear structure. Short-range correlations
can significantly deplete the available single-particle strength around the
Fermi surface and thus provide a reduction mechanism of the pairing gap. Here,
we study this effect in the singlet and triplet channels of both neutron matter
and symmetric nuclear matter. Our calculations use phase-shift equivalent
interactions and chiral two-body and three-body interactions as a starting
point. We find an unambiguous reduction of the gap in all channels with very
small dependence on the NN force in the singlet neutron matter and the triplet
nuclear matter channel. In the latter channel, short range correlations alone
provide a 50% reduction of the pairing gap.Comment: Final version, as published in journal after refereein
Endohedrally confined hydrogen atom with a moving nucleus
We studied the hydrogen atom as a system of two quantum particles in
different confinement conditions; a spherical-impenetrable-wall cavity and a
fullerene molecule cage. The motion is referred to the center of spherical
cavities, and the Schr\"{o}dinger equation solved by means of a Generalized
Sturmian Function expansion in spherical coordinates. The solutions present
different properties from the ones described by the many models in the
literature, where the proton is fixed in space and only the electron is
considered as a quantum particle. Our results show that the position of the
proton (i.e. the center of mas of the H atom) is very sensitive to the
confinement condition, and could vary substantially from one state to another,
from being sharply centered to being localized outside the fullerene molecule.
Interchange of the localization characteristics between the states when varying
the strength of the fullerene cage and mass occurred through crossing
phenomena
Correlations within the Non-Equilibrium Green's Function Method
Non-equilibrium Green's Function (NGF) method is a powerful tool for studying
the evolution of quantum many-body systems. Different types of correlations can
be systematically incorporated within the formalism. The time evolution of the
single-particle Green's functions is described in terms of the Kadanoff-Baym
equations. The current work initially focuses on introducing the correlations
within infinite nuclear matter in one dimension and then in a finite system in
the NGF approach. Starting from the harmonic oscillator Hamiltonian, by
switching on adiabatically the mean-field and correlations simultaneously, a
correlated state with ground-state characteristics is arrived at within the NGF
method. Furthermore the use of cooling to for improving the adiabatic switching
is explored.Comment: Contribution to Proc. 5th Conference on Nuclei and Mesoscopic
Physics, E Lansing, 6-10 March 2017; 9 pages, 8 figure
Microscopic calculations of spin polarized neutron matter at finite temperature
The properties of spin polarized neutron matter are studied both at zero and
finite temperature within the framework of the Brueckner--Hartree--Fock
formalism, using the Argonne v18 nucleon-nucleon interaction. The free energy,
energy and entropy per particle are calculated for several values of the spin
polarization, densities and temperatures together with the magnetic
susceptibility of the system. The results show no indication of a ferromagnetic
transition at any density and temperature.Comment: 19 pages, 5 figure
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