4,550 research outputs found
Study of non-equilibrium effects and thermal properties of heavy ion collisions using a covariant approach
Non-equilibrium effects are studied using a full Lorentz-invariant formalism.
Our analysis shows that in reactions considered here, no global or local
equilibrium is reached. The heavier masses are found to be equilibrated more
than the lighter systems. The local temperature is extracted using hot Thomas
Fermi formalism generalized for the case of two interpenetrating pieces of
nuclear matter. The temperature is found to vary linearly with bombarding
energy and impact parameter whereas it is nearly independent of the mass of the
colliding nuclei. This indicates that the study of temperature with medium size
nuclei is also reliable. The maximum temperatures obtained in our approach are
in a nice agreement with earlier calculations of other approaches. A simple
parametrization of maximal temperature as a function of the bombarding energy
is also given.Comment: LaTex-file, 17 pages, 8 figures (available upon request), Journal of
Physics G20 (1994) 181
Domain Growth in Random Magnets
We study the kinetics of domain growth in ferromagnets with random exchange
interactions. We present detailed Monte Carlo results for the nonconserved
random-bond Ising model, which are consistent with power-law growth with a
variable exponent. These results are interpreted in the context of disorder
barriers with a logarithmic dependence on the domain size. Further, we clarify
the implications of logarithmic barriers for both nonconserved and conserved
domain growth.Comment: 7 pages, 4 figure
Spinodal Decomposition in Thin Films: Molecular Dynamics Simulations of a Binary Lennard-Jones Fluid Mixture
We use molecular dynamics (MD) to simulate an unstable homogeneous mixture of
binary fluids (AB), confined in a slit pore of width . The pore walls are
assumed to be flat and structureless, and attract one component of the mixture
(A) with the same strength. The pair-wise interactions between the particles is
modeled by the Lennard-Jones potential, with symmetric parameters that lead to
a miscibility gap in the bulk. In the thin-film geometry, an interesting
interplay occurs between surface enrichment and phase separation.
We study the evolution of a mixture with equal amounts of A and B, which is
rendered unstable by a temperature quench. We find that A-rich surface
enrichment layers form quickly during the early stages of the evolution,
causing a depletion of A in the inner regions of the film. These
surface-directed concentration profiles propagate from the walls towards the
center of the film, resulting in a transient layered structure. This layered
state breaks up into a columnar state, which is characterized by the lateral
coarsening of cylindrical domains. The qualitative features of this process
resemble results from previous studies of diffusive Ginzburg-Landau-type models
[S.~K. Das, S. Puri, J. Horbach, and K. Binder, Phys. Rev. E {\bf 72}, 061603
(2005)], but quantitative aspects differ markedly. The relation to spinodal
decomposition in a strictly 2- geometry is also discussed.Comment: 37 pages, 11 figures, to appear in Phys. Rev.
Study of elliptical flow at VECC-SCC500 energies
We study the transverse momentum dependence of elliptical flow at VECC
energies by using the projectiles having masses lying between 16 and 56 units.
The detailed study in this direction will be fruitful for experimentlists
The study of multifragmentation around transition energy in intermediate energy heavy-ion collisions
Fragmentation of light charged particles is studied for various systems at
different incident energies between 50 and 1000 MeV/nucleon. We analyze
fragment production at incident energies above, below and at transition
energies using the isospin dependent quantum molecular dynamics(IQMD) model.
The trends observed for the fragment production and rapidity distributions
depend upon the incident energy, size of the fragments, composite mass of the
reacting system as well as on the impact parameter of the reaction. The free
nucleons and light charged particles show continous homogeneous changes
irrespective of the transition energies indicating that there is no relation
between the transition energy and production of the free as well as light
charged particles
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