We review understanding of kinetics of fluid phase separation in various space dimensions. Morphological differences, percolating or disconnected, based on overall composition in a binary liquid or density in a vapor-liquid system, have been pointed
out. Depending upon the morphology, various possible mechanisms and corresponding theoretical predictions for domain growth are discussed. On computational front, useful models and simulation methodologies have been presented. Theoretically predicted growth laws have been tested via molecular dynamics simulations of vapor-liquid transitions. In case of disconnected structure, the mechanism has been confirmed directly. This is a brief review on the topic for a special issue on coarsening dynamics, expected to appear in Comptes Rendus Physique.
Behavior of two-time autocorrelation during the phase separation in solid binary mixtures are studied via numerical solutions of the Cahn-Hilliard equation as well as Monte Carlo simulations of the Ising model. Results are analyzed via state-of-the-a
rt methods, including the finite-size scaling technique. Full forms of the autocorrelation in space dimensions $2$ and $3$ are obtained empirically. The long time behavior are found to be power-law type, with exponents unexpectedly higher than the ones for the ferromagnetic ordering. Both Chan-Hilliard and Ising models provide results consistent with each other.
We have fabricated and characterized the Landau level spin diode in GaAs two dimensional hole system. We used the hole Landau level spin diode to probe the hyperfine coupling between the hole and nuclear spins and found no detectable net nuclear pola
rization, indicating that hole-nuclear spin flip-flop processes are suppressed by at least three orders of magnitude compared to GaAs electron systems.
The end point energies of nuclear $beta$ decays have been measured with a segmented planar Ge LEPS detector using both singles and coincidence techniques. The $beta - gamma$ coincidence has been performed with a segmented planar Ge LEPS and a single
10$%$ HPGe detector. The $gamma$ ray and $beta$ particle responses of the Segmented planer Ge LEPS detector were studied using monte carlo simulation code GEANT3. The experimentally obtained $beta$ spectrum was in reasonably good agreement with the simulation results. The experimental end point energies are determined with substantial accuracy for some of the known $beta$ decays in $^{106}$Rh, $^{210}$Bi and $^{90}$Y. The end point energies corresponding to three weak branches in $^{106}$Rh $rightarrow$ $^{106}$Pd decay has been measured for the first time.
An open question in the field of non-equilibrium statistical physics is whether there exists a unique way through which non-equilibrium systems equilibrate irrespective of how far they are away from equilibrium. To answer this question we have genera
ted non-equilibrium states of various types of systems by molecular dynamics simulation technique. We have used a statistical method called system identification technique to understand the dynamical process of equilibration in reduced dimensional space. In this paper, we have tried to establish that the process of equilibration is unique.
We present a study of the equilibration process of nonequilibrium systems by means of molecular dynamics simulation technique. The nonequilibrium conditions are achieved in systems by defining velocity components of the constituent atoms randomly. Th
e calculated Shannon en- tropy from the probability distribution of the kinetic energy among the atoms at different instants during the process of equilibration shows oscillation as the system relaxes towards equilibrium. Fourier transformations of these oscillating Shannon entropies reveal the existance of Debye frequency of the concerned system. From these studies it was concluded that the signature of the equilibration process of dynamical systems is the time invariance of Shannon entropy.
We focus on evaluating transport coefficients like drag and diffusion of heavy quarks (HQ) passing through Quark Gluon Plasma using perturbative QCD (pQCD). Experimental observable like nuclear suppression factor (RAA) of HQ is evaluated for both zer
o and non-zero baryonic chemical potential ({mu}_B) scenarios using Fokker- Planck equation. Theoretical estimates of RAA are contrasted with experiments.
Electron Capture (EC) decay of $^{146}$Gd($it{t_{1/2}}$ = 48d) to the low lying states of $^{146}$Eu has been studied using high-resolution $gamma$ ray spectroscopy. The $^{146}$Gd activity was produced by ($alpha$, 2n) reaction at E$_{alpha}$ = 32 M
eV using 93.8% enriched $^{144}$Sm target. The level structure has been considerably modified from the measurement of $gamma$ ray singles, $gammagamma$ coincidences and decay half lives. Lifetime measurement has been performed for the 3$^-$ (114.06 keV) and 2$^-$ (229.4 keV) levels of $^{146}$Eu using Mirror Symmetric Centroid Difference (MSCD) method with LaBr$_3$ (Ce) detectors. The lifetimes for these two states have been found to be 5.38 $pm$ 2.36 ps and 8.38 $pm$ 2.19 ps respectively. Shell model calculation has been performed using OXBASH code in order to interpret the results.
We study the behavior of the dynamical fermion mass when infrared divergences and mass shell singularities are present in a gauge theory. In particular, in the massive Schwinger model in covariant gauges we find that the pole of the fermion propagato
r is divergent and gauge dependent at one loop, but the leading singularities cancel in the quenched rainbow approximation. On the other hand, in physical gauges, we find that the dynamical fermion mass is finite and gauge independent at least up to one loop.
We report quantum dots fabricated on very shallow 2-dimensional electron gases, only 30 nm below the surface, in undoped GaAs/AlGaAs heterostructures grown by molecular beam epitaxy. Due to the absence of dopants, an improvement of more than one orde
r of magnitude in mobility (at 2E11 /cm^2) with respect to doped heterostructures with similar depths is observed. These undoped wafers can easily be gated with surface metallic gates patterned by e-beam lithography, as demonstrated here from single-level transport through a quantum dot showing large charging energies (up to 1.75 meV) and excited state energies (up to 0.5 meV).
