1,534 research outputs found
Properties of spatial arrangement of V-type defects in irradiated materials: 3D-modelling
We consider the dynamics of pattern formation in a system of point defects
under sustained irradiation within the framework of the rate theory. In our
study we generalize the standard approach taking into account a production of
defects by elastic fields and a stochastic production representing internal
multiplicative noise. Using 3D-modelling we have shown that with the damage
rate growth, a morphology of clusters composed of vacancies changes. The same
effect is observed with variation in the multiplicative noise intensity.
Stationary patterns are studied by means of correlation analysis.Comment: 12 pages, 7 figure
Universality and self-similar behaviour of non-equilibrium systems with non-Fickian diffusion
Analytical approaches describing non-Fickian diffusion in complex systems are
presented. The corresponding methods are applied to the study of statistical
properties of pyramidal islands formation with interacting adsorbate at
epitaxial growth. Using the generalized kinetic approach we consider
universality, scaling dynamics and fractal properties of pyramidal islands
growth. In the framework of generalized kinetics, we propose a theoretical
model to examine the numerically obtained data for averaged islands size, the
number of islands and the corresponding universal distribution over the island
size.Comment: 10 pages, 6 figure
Colored noise influence on the system evolution
We present a picture of phase transitions of the system with colored
multiplicative noise. Considering the noise amplitude as the power-law
dependence of the stochastic variable we show the way to phase
transitions disorder-order and order-disorder. The governed equations for the
order parameter and one-time correlator are obtained and investigated in
details. The long-time asymptotes in the disordered and ordered domains on the
phase portrait of the system are defined.Comment: 12 pages, 8 figures, LaTeX. Submitted to EPJ-
Three-body treatment of the penetration through the Coulomb field of a two-fragment nucleus
On the basis of the Faddeev integral equations method and the Watson-
Feshbach concept of the effective (optical) interaction potential, the first
fully consistent three-body approach to the description of the penetration of a
charged particle through the Coulomb field of a two-particle bound complex
(composed of one charged and one neutral particles) has been developed. A
general formalism has been elaborated and on its basis, to a first
approximation in the Sommerfeld parameter, the influence of the nuclear
structure on the probability of the penetration of a charged particle (the
muon, the pion, the kaon and the proton) through the Gamow barrier of a
two-fragment nucleus (the deuteron and the two lightest lambda hypernuclei,
lambda hypertriton and lambda hyperhelium-5, has been calculated and studied.Comment: LaTeX, 30 pages, 4 eps figure
Global survey of star clusters in the Milky Way: III. 139 new open clusters at high Galactic latitudes
Context. An earlier analysis of the Milky Way Star Cluster (MWSC) catalogue revealed an apparent lack of old (t � 1 Gyr) open clusters in the solar neighbourhood (d � 1 kpc). Aims. To fill this gap we undertook a search for hitherto unknown star clusters, assuming that the missing old clusters reside at high Galactic latitudes | b | > 20°. Methods. We were looking for stellar density enhancements using a star count algorithm on the 2MASS point source catalogue. To increase the contrast between potential clusters and the field, we applied filters in colour-magnitude space according to typical colour-magnitude diagrams of nearby old open clusters. The subsequent comparison with lists of known objects allowed us to select thus far unknown cluster candidates. For verification they were processed with the standard pipeline used within the MWSC survey for computing cluster membership probabilities and for determining structural, kinematic, and astrophysical parameters. Results. In total we discovered 782 density enhancements, 524 of which were classified as real objects. Among them 139 are new open clusters with ages 8.3 < log (t [yr]) < 9.7, distances d< 3 kpc, and distances from the Galactic plane 0.3 <Z< 1 kpc. This new sample has increased the total number of known high latitude open clusters by about 150%. Nevertheless, we still observe a lack of older nearby clusters up to 1 kpc from the Sun. This volume is expected to still contain about 60 unknown clusters that probably escaped our detection algorithm, which fails to detect sparse overdensities with large angular size
Morphology change of the silicon surface induced by Ar ion beam sputtering
Two-level modeling for nanoscale pattern formation on silicon target by
Ar ion sputtering is presented. Phase diagram illustrating possible
nanosize surface patterns is discussed. Scaling characteristics for the
structure wavelength dependence versus incoming ion energy are defined. Growth
and roughness exponents in different domains of the phase diagram are obtained.Comment: 11 pages, 5 figure
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