207 research outputs found
Two-Pion Exchange Currents in Photodisintegration of the Deuteron
Chiral effective field theory (ChEFT) is a modern framework to analyze the
properties of few-nucleon systems at low energies. It is based on the most
general effective Lagrangian for pions and nucleons consistent with the chiral
symmetry of QCD. For energies below the pion-production threshold it is
possible to eliminate the pionic degrees of freedom and derive nuclear
potentials and nuclear current operators solely in terms of the nucleonic
degrees of freedom. This is very important because, despite a lot of experience
gained in the past, the consistency between two-nucleon forces, many-nucleon
forces and the corresponding current operators has not been achieved yet. In
this presentation we consider the recently derived long-range two-pion exchange
(TPE) contributions to the nuclear current operator which appear at next-to
leading order of the chiral expansion. These operators do not contain any free
parameters. We study their role in the deuteron photodisintegration reaction
and compare our predictions with experimental data. The bound and scattering
states are calculated using five different chiral N2LO nucleon-nucleon (NN)
potentials which allows to estimate the theoretical uncertainty at a given
order in the chiral expansion. For some observables the results are very close
to the reference predictions based on the AV18 NN potential and the current
operator (partly) consistent with this force.Comment: Contribution to the 12th International Conference on Meson-Nucleon
Physics and the Structure of the Nucleon (MENU2010), Williamsburg, USA, May
31-June 4, 201
Deuteron disintegration in three dimensions
We compare results from the traditional partial wave treatment of deuteron
electro-disintegration with a new approach that uses three dimensional
formalism. The new framework for the two-nucleon (2N) system using a complete
set of isospin - spin states made it possible to construct simple
implementations that employ a very general operator form of the current
operator and 2N states.Comment: 24 pages, 15 eps figure
Model and optimization of electromagnetic filtration of metals
Electromagnetic buoyancy force causes the movement of non-conducive particles in a conducting liquid under electromagnetic field. The phenomenon allows filtration of small inclusions from molten metals. This paper presents a mathematical model of the filtration process under alternating electromagnetic field and the methodology for maximizing its efficiency
A Three-Dimensional Treatment of the Three-Nucleon Bound State
Recently a formalism for a direct treatment of the Faddeev equation for the
three-nucleon bound state in three dimensions has been proposed. It relies on
an operator representation of the Faddeev component in the momentum space and
leads to a finite set of coupled equations for scalar functions which depend
only on three variables. In this paper we provide further elements of this
formalism and show the first numerical results for chiral NNLO nuclear forces.Comment: 25 pages, 7 figures (34 eps files
Utjecaj parametara indukcijske elektro peći na brzinu masenog prijenosa u tekućoj fazi
This article is an analysis of the results obtained under the tests aimed at determination of the influence exerted by the current frequency of an induction furnace on the mass transfer coefficient for liquid metallic phase.U radu su analizirani rezultati dobiveni testiranjem provedenim s ciljem utvrditi utjecaj frekvencije industrijske peći na maseni koeficijent prijenosa u tekućoj metalnoj fazi
Final state interaction effects in mu-capture induced two-body decay of 3He
The mu-capture process on 3He leading to a neutron, a deuteron and a
mu-neutrino in the final state is studied. Three-nucleon Faddeev wave functions
for the initial 3He bound and the final neutron-deuteron scattering states are
calculated using the BonnB and Paris nucleon-nucleon potentials. The nuclear
weak current operator is restricted to impulse approximation. Large effects on
the decay rates of the final state interaction are found. The comparison to
recent experimental data shows that the inclusion of final state interactions
drastically improves the description of the data.Comment: 14 pages, 6 eps figure
Triton photodisintegration in three-dimensional approach
Two- and three- particles photodisintegration of the triton is investigated
in a three-dimensional (3D) Faddeev approach. For this purpose the Jacobi
momentum vectors for three particles system and spin-isospin quantum numbers of
the individual nucleons are considered. Based on this picture the three-nucleon
Faddeev integral equations with the two-nucleon interaction are formulated
without employing the partial wave decomposition. The single nucleon current as
well as and like exchange currents are used in an appropriate
form to be employed in 3D approach. The exchange currents are derived from AV18
NN force. The two-body t-matrix, Deuteron and Triton wave functions are
calculated in the 3D approach by using AV18 potential. Benchmarks are presented
to compare the total cross section for the two- and three- particles
photodisintegration in the range of . The 3D Faddeev
approach shows promising results
Modeling of solidification of MMC composites during gravity casting process
The paper deals with computer simulation of gravity casting of the metal matrix composites reinforced with ceramics (MMC) into sand mold. The subject of our interest is aluminum matrix composite (AlMMC) reinforced with ceramic particles i.e. silicon carbide SiC and glass carbon Cg. The created model describes the process taking into account solidification and its influence on the distribution of reinforcement particles. The computer calculation has been carried out in 2D system with the use of Navier-Stokes equations using ANSYS FLUENT 13. The Volume of Fluid approach (VOF) and enthalpy method have been used to model the air-fluid free surface (and also volume fraction of particular continuous phases) and the solidification of the cast, respectively
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