• Volume 20, Issue 3

      March 1983,   pages  175-265

    • Relative strengths of the competing multipoles in the K and L series x-ray spectra in theNR limit

      V S Edlabadkar Chintamani Mande

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      For most of the transitions of theK andL series x-ray spectra the ratio of the contributions of the competing multipoles, δ2, is independent of the radial matrix element in the non-relativistic limit. In the present paper calculations of δ2 are made in the non-relativistic limit which give the relative strengths of the two closely competing electric and magnetic multipoles. The dominant mode in the emission processes of the transitions in theK andL series x-ray spectra has been assigned on the basis of these calculations.

    • Raman scattering study of LiKSO4—phases II and III

      M L Bansal S K Deb A P Roy V C Sahni

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      Detailed Raman scattering investigation of LiKSO4 in phases II and III across the transition temperatureTc ≃ 700 K is reported. Abrupt change in frequency and line width of the external and internal modes have been observed. Analysis of the results suggests lithium positional disorder and sulphate orientational disorder in the high temperature phase (II). The results also throw some light on the existence of twin domains in the crystal.

    • Generalised direct action and absorber theory of radiation

      R V Kamat

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      It is known that corresponding to a field theory of a tensor of arbitrary rank, there exists a direct-action theory under certain conditions. An attempt is therefore made to construct an explicit direct-action theory for a tensor field of rankN in such a form that the absorber theory of radiation may be worked out using the methods made so well known by Wheeler-Feynman and Hoyle-Narlikar. It is possible to recover the familiar electromagnetic theory corresponding to the case ofN = 1.

    • Perturbation theory for a microemulsion with triangular well potential

      M C Somasekhara Reddy A Kamalakara Murthy

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      The perturbation approach of Barker and Henderson (1967, 1968) has been applied to a microemulsion obeying triangular well potential as a perturbative attractive tail over the Percus-Yevick (PY) hard sphere model by calculating the Rayleigh ratio,R90, under the mean spherical approximations. The results are in better agreement with experimental values.

    • Weak neutral current effects in elastic electron deuteron scattering

      M V N Murthy G Ramachandran S K Singh

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      We study the effect of weak neutral currents in elastic electron deuteron scattering on both unpolarized and polarized deuteron targets. Theoretical expressions have been derived for the polarized electron asymmetry, polarized target asymmetry and recoil deuteron vector polarization within the framework of impulse approximation. We show that these polarization parameters can give vital information on the space-time and isospin structure of the hadronic weak neutral current. In particular, our numerical estimates show that a measurement of polarized target asymmetry is sensitive to the isoscalar axial vector piece in the hadronic neutral current which, though zero in the Weinberg-Salam model, is not completely ruled out by the data.

    • Viscous fluid motion around the Kerr-Newman black hole

      S K Saha

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      In some recent papers, it has been shown that electrovac spacetimes may sometimes be interpreted as space-time filled with a viscous fluid—one such spacetime being the Kerr-Newman metric. Here the possible fluid motion in that case is studied in some detail and some interesting features of the motion in the black hole region are pointed out.

    • Fluid-dynamical representations of the Dirac equation

      Sambhu N Datta

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      A relative kinetic mass operator is defined bym =c−2·(E), and it is shown that bt using it in a symmetric form one can correlate the (charge) velocity operatorα in the Dirac theory exactly with the general quantum mechanical momentum —ih∇. Then the net force, defined as the rate of change of the relative momentum with time, is exactly equal to the Lorentz force. The contribution due to the time variation of mass equals the negative of space variation of the scalar potential, the Newtonian force, whereas the time variation of the charge current absorbs the entire vector potential dependence. The analogous Euler equations can be written either in terms of the charge current or in terms of the mass current. For a many particle system one needs the usual net single particle parameters and the consideration of both the direct and exchange contributions of the two particle interaction. These Euler equations yield two different conditions of the stationary state. It is shown that the charge-current condition is necessary but not sufficient, whereas the mass-current condition retains the appropriate scalar potential dependence. These two conditions are compared for the spherically symmetric case. The charge density, charge current and relative mass current are tabulated for atomic spinors. Differences between the quantum and classical forces for the H2+ molecular ion exhibit the inadequacy of ordinary atomic spinor basis in forming molecular spinors.

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