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By
Mishra, Babaji Charan; Pradhan, Trilochan
1 Citations
A quantum field theoretic formulation of atomic collision phenomena involving nonrelativistic free and bound systems is developed and a calculational procedure in terms of Feynman diagrams is prescribed. Matrix elements of several atomic collision processes have been calculated. In most cases standard quantum mechanical results are reproduced. But in some cases new terms appear in the scattering matrix whose contribution though negligibly small in the low energy region, become important at higher energies.
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By
Idiculla, Roschen; Viswanathan, K S
2 Citations
The dispersion equation for oblique propagation of the wave in thexy plane for heliconphonon interaction has been derived and numerical studies have been carried out on the nature of variation of the four different modes with the magnetic field and the inclination of the magnetic field with the direction of propagation.
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By
Patil, M G; Lawangar, R D
The phosphorescence decay of a series of strontium sulphide microcrystalline phosphors prepared with varying amounts of neodymium as an activator has been studied at room temperature. The decay obeys the relationI =I_{0}t^{−b} withb lying between 0·35 and 0·98. The trap depths have been evaluated by peeling off logIt curves. The results show that the distribution of trap levels is likely to be quasiuniform and the process of retrapping during luminescence is negligible.
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By
Andhradev, K; Kulkarni, R G
The effect of nuclear Coulomb potential in rotating nuclei has been studied in the ThomasFermi approach. The numerical calculations of typical rotating nuclei show that Coulomb potential plays an important role in the rotational mass regions 150–190 and >224.
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By
Lal, R; Joshi, S K
2 Citations
It has been shown that an analysis of radial stationary state wave functions of a particle in terms of their loops leads to such continuous, singlevalued and finite functions which represent a practically convenient form of the radial wave packets of that particle at various positions. The radial wave packets have been used to investigate target distortion in electronatom collisions. The distortion of the target is defined in terms of quantummechanical probabilities given by the wave packets. A closed expression which depends upon the position of the colliding electron, is obtained for the potential energy of the target in the field of the colliding electron.
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By
Prasanna, A R; Chakraborty, D K
5 Citations
The charged particle orbits in electromagnetic fields on Kerr background as viewed from a locally nonrotating frame do not exhibit nongyrating bound orbits, which was an essential feature in the earlier study of Prasanna and Vishveshwara, thus showing the non gyration to be due to the effect of dragging of inertial frames produced by the rotating black hole.
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By
Peraiah, A.; Raghunath, G.
We have treated formation of spectral lines in a commoving frame where photoionization is predominant over collisional processes. We have assumed that the radiation field for causing photoionization is a function of Planck function. We have also considered the situation in which the continuum contributes to the radiation in the line. In all the models the quantityB/A (ratio of outer to inner radii) is kept equal to 10 and the total optical depth is taken to be 10^{3}. The velocity is assumed to be varying according to the lawdV/dτ ∼ < 1/τ whereτ is the optical depth (τ > 0) in the given shell. The velocities at the innermost radius (r =A) are set equal to 0 and at the outermost radius (r =B), the maximum velocities are taken to be 0, 1, 3 and 10 Doppler units. The calculated line profiles are those seen by an observer at infinity.P Cygnitype profiles are observed in the case of a medium with no continuum absorption. For a medium with continuum absorption double peaked asymmetric profiles are noticed when the velocities are small; the two emission peaks merge into a single asymmetric peak for larger velocities.
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