817 research outputs found
Nematic - Isotropic Transition in Porous Media - a Monte Carlo Study
We propose a lattice model to simulate the influence of porous medium on the
Nematic - Isotropic transition of liquid crystal confined to the pores. The
effects of pore size and pore connectivity are modelled through a disorder
parameter. Monte Carlo calculations based on the model leads to results that
compare well with experiments.Comment: 11 pages; 4 figure
Column Flotation: Theory and Practice
Column flotation which employs a counter-current flow of slurry and air bubbles has proved to be better alternative to the conventional mechanical cells for separation of minerals. Because of the distince advantages of column flotation over mechanical cells, it is gaining wider acceptance in industry. Realizing the potentioal of column flotation, RRL Bhubaneswar also took initiative in the early ixties to develop column flotation technology for Indian ores. In the early stages, operation and design of columns wewe mainly based on experience. But with the increasing commercial installations, systematic investi-gations bave been carried out by several workers. In this paper an attempt is made to review the development of column flotation for concentration of law grade ores. The basic principles and applications of column flotation have been described. The salient results obtained at RRL, Bhubaneswar have been highlighted
Study of np-scattering for S, P and D Waves using Deng-Fan Potential by Phase Function Method
In this paper, the np - scattering phase shifts and cross section for S,P and
D partial waves have been obtained for energies below the pion threshold, by
considering Deng-Fan potential as model of interaction. The radial time
independent Schr\"odinger equation has been analytically solved using Nikiforov
- Uvarov method to obtain the energy expression for ground state of np system.
Utilising this, the scattering phase shifts for have been obtained
using phase function method. The phase equations for various scattering states
, , , , and have been
numerically solved for obtaining corresponding scattering phase shifts and
their respective partial cross section. The total scattering cross sections
computed at various energies are found to be closely matching with experimental
data. The low energy scattering parameters determined from scattering phase
shifts of and are reasonably close to experimental ones. Hence,
Deng-Fan potential is a good phenomenological potential to understand the np -
scattering system.Comment: 11 pages, 4 figures, 2 table
Comparative Study of alpha-alpha interaction potentials constructed using various phenomenological models
In this paper, we have made a comparative study of alpha-alpha scattering
using different phenomenological models like Morse, double Gaussian, double
Hulthen, Malfliet-Tjon and double exponential for the nuclear interaction and
atomic Hulthen as screened coulomb potential. The phase equations for S, D and
G channels have been numerically solved using 5th order Runge-Kutta Method to
compute scattering phase shifts for elastic scattering region consisting of
energies up to 25.5 MeV. The model parameters in each of the chosen potentials
were varied in an iterative fashion to minimize the mean absolute percentage
error between simulated and expected scattering phase shifts. A comparative
analysis revealed that, all the phenomenological models result in exactly
similar inverse potentials with closely matching mean absolute percentage error
values for S, D and G state. One can conclude that any mathematical function
that can capture the basic features of two body interaction would always guide
correctly in construction of inverse potentials.Comment: 11 pages, 3 figures, 4 Table
Neutron-Proton Scattering Phase Shifts in S-Channel using Phase Function Method for Various Two Term Potentials
The scattering phase shifts for n-p scattering have been modeled using various two term exponential type potentials such as Malfliet-Tjon, Manning-Rosen and Morse to study the phase shifts in the S-channels. As a first step, the model arameters for each of the potentials are determined by obtaining binding energy of the deuteron using matrix methods vis-a-vis Variational Monte-Carlo (VMC) technique to minimize the percentage error w.r.t. the experimental value. Then, the first order ODE as given by phase function method (PFM), is numerically solved using 5th order Runge-Kutta (RK-5) technique, by substituting the obtained potentials for calculating phase shifts for the bound 3S1 channel. Finally, the potential parameters are varied in least squares sense using VMC technique to obtain the scattering phase-shifts for each of the potentials in the 1S0 channel. The numerically obtained values are seen to be matching with those obtained using other analytical techniques and a comparative analysis with the experimental values up to 300 MeV is presented
Constructing Inverse Scattering Potentials for {\alpha}-{\alpha} System using Reference Potential Approach
Background: An accurate way to incorporate long range Coulomb interaction
alongside short-range nuclear interaction has been a challenge for theoretical
physicists. Purpose: In this paper, we propose a methodology based on the
reference potential approach for constructing inverse potentials of alpha-alpha
scattering. Methods: Two smoothly joined Morse potentials, regular for
short-range nuclear interaction and inverted for long range Coulomb, are used
in tandem as a reference potential in the phase function method to obtain the
scattering phase shifts for the S, D and G states of alpha-alpha scattering.
The model parameters are optimized by choosing to minimize the mean absolute
percentage error between the obtained and experimental scattering phase shift
values. Results: The constructed inverse potentials for S, D and G states have
resulted in mean absolute percentage errors of 0.8, 0.5, and 0.4 respectively.
The obtained resonances for D and G states closely match the experimental ones.
Conclusion: The reference potential approach using a combination of smoothly
joined Morse functions is successful in accurately accounting for the Coulomb
interaction between charged particles in nuclear scattering studies.Comment: 10 pages, 4 figures, 2 Table
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