1,012 research outputs found
Nuclear Force from Lattice QCD
The first lattice QCD result on the nuclear force (the NN potential) is
presented in the quenched level. The standard Wilson gauge action and the
standard Wilson quark action are employed on the lattice of the size 16^3\times
24 with the gauge coupling beta=5.7 and the hopping parameter kappa=0.1665. To
obtain the NN potential, we adopt a method recently proposed by CP-PACS
collaboration to study the pi pi scattering phase shift. It turns out that this
method provides the NN potentials which are faithful to those obtained in the
analysis of NN scattering data. By identifying the equal-time Bethe-Salpeter
wave function with the Schroedinger wave function for the two nucleon system,
the NN potential is reconstructed so that the wave function satisfies the
time-independent Schroedinger equation. In this report, we restrict ourselves
to the J^P=0^+ and I=1 channel, which enables us to pick up unambiguously the
``central'' NN potential V_{central}(r). The resulting potential is seen to
posses a clear repulsive core of about 500 MeV at short distance (r < 0.5 fm).
Although the attraction in the intermediate and long distance regions is still
missing in the present lattice set-up, our method is appeared to be quite
promising in reconstructing the NN potential with lattice QCD.Comment: A talk given at the XXIV International Symposium on Lattice Field
Theory (Lattice2006), Tucson, Arizona, USA, July 23-28, 2006, 3 figures,
7page
Quantum reservoirs with ion chains
Ion chains are promising platforms for studying and simulating quantum
reservoirs. One interesting feature is that their vibrational modes can mediate
entanglement between two objects which are coupled through the vibrational
modes of the chain. In this work we analyse entanglement between the transverse
vibrations of two heavy impurity defects embedded in an ion chain, which is
generated by the coupling with the chain vibrations. We verify general scaling
properties of the defects dynamics and demonstrate that entanglement between
the defects can be a stationary feature of these dynamics. We then analyse
entanglement in chains composed of tens of ions and propose a measurement
scheme which allows one to verify the existence of the predicted entangled
state.Comment: 14 pages, 12 figure
Relativistic two-pion exchange nucleon-nucleon potential: configuration space
We have recently performed a relativistic chiral expansion of the
two-pion exchange potential, and here we explore its configuration space
content. Interactions are determined by three families of diagrams, two of
which involve just and , whereas the third one depends on
empirical coefficients fixed by subthreshold data. In this sense, the
calculation has no adjusted parameters and gives rise to predictions, which are
tested against phenomenological potentials. The dynamical structure of the
eight leading non-relativistic components of the interaction is investigated
and, in most cases, found to be clearly dominated by a well defined class of
diagrams. In particular, the central isovector and spin-orbit, spin-spin, and
tensor isoscalar terms are almost completely fixed by just and .
The convergence of the chiral series in powers of the ratio (pion mass/nucleon
mass) is studied as a function of the internucleon distance and, for 1 fm,
found to be adequate for most components of the potential. An important
exception is the dominant central isoscalar term, where the convergence is
evident only for 2.5 fm. Finally, we compare the spatial behavior of the
functions that enter the relativistic and heavy baryon formulations of the
interaction and find that, in the region of physical interest, they differ by
about 5%.Comment: 27 pages, 33 figure
Study on unsteady cavitating flow simulation around marine propeller using a RANS CFD code.
The authors have been investigating the possibility of the application of CFD to the propeller performance evaluation and optimization. In these previous papers [1,2], the authors presented CFD simulation of non-cavitating and cavitating flow around a marine propeller using a commercial CFD code. A good agreement with the experiment was confirmed for the non-cavitating flow. Various validations were also carried out for the cavitating flow, and the followings were revealed. First, we confirmed that the cavity shape in a uniform flow was qualitatively well estimated, but the difference between two propellers, of which the blade sections were somewhat different, were not reproduced. Secondary, the cavity pattern in the non-uniform flow was also qualitatively well estimated, but the resulting pressure fluctuation was not validated. In this paper, the systematic experiment was carried out using two propellers, whose dimensions were very similar, to study the above issues, and simulation was carried out for the same cases. In the uniform cavitating flow simulation, the discrepancy of cavity shape around two propellers, whose dimension were very similar, was reproduced, and the quantitative validation of the fluid force such as thrust was done. In the non-uniform cavitating flow simulation, the comparison of the cavity pattern with the experiment and the quantitative validation of the fluctuating pressure on the wall of the cavitation tunnel were done.http://deepblue.lib.umich.edu/bitstream/2027.42/84265/1/CAV2009-final68.pd
Preparation of 169Yb Calibration Sources for the Measurement of Electron Anti-Neutrino Mass
開始ページ、終了ページ: 冊子体のページ付
Measurement of neutron diffraction with compact neutron source RANS
Diffraction is used as a measurement technique for crystal structure. X-rays or electron beam with wavelength that is close to the lattice constant of the crystal is often used for the measurement. They have sensitivity in surface
(0.01mm) of heavy metals due to the mean free path for heavy ions. Neutron diffraction has the probe of the internal structure of the heavy metals because it has a
longer mean free path than that of the X-rays or the electrons. However, the neutron diffraction measurement is not widely used because large facilities are required in the many neutron sources. RANS (Riken Accelerator-driven Compact Neutron Source) is developed as a neutron source which is usable easily in laboratories and factories. In RANS, fast neutrons are generated by 7MeV protons colliding on a Be target. Some fast neutrons are moderated with polyethylene to thermal neutrons. The thermal neutrons of 10meV which have wavelength of 10nm can be used for the
diffraction measurement. In this study, the texture evolution in steels was measured with RANS and the validity of the compact neutron source was proved. The texture of IF steel sheets with the thickness of 1.0mm was measured with 10minutes run. The resolution is 2% and is enough to analyze a evolution in texture due to compression/tensile deformation or a volume fraction of two phases in the steel sample. These results have proven the possibility to use compact neutron source for the analysis of mesoscopic structure of metallic materials
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