• Volume 19, Issue 2

      August 1982,   pages  117-202

    • Dielectric behaviour of anisotropic ionic crystals

      M R Srinivasan P S Narayanan

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      In the case of cubic ionic crystals Havinga has shown that the temperature variation of dielectric constant could be described in terms of volume and temperature effects. By extending his formalism to anisotropic, ionic crystals it has been shown that unlike in cubic ionic crystals where the volume effect consists of a change in the number per unit volume of the polarizable particles and their polarizability with volume, in the case of anisotropic ionic crystals, in addition to these, a variation in the anisotropy of polarizability due to uneven thermal expansion also has to be taken into account. This method of analysis has been examined by taking rutile as an example.

    • AC conductivity and dielectric properties of sulphate glasses

      H G K Sundar K J Rao

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      AC conductivity and dielectric properties of sulphate glasses have been studied as a function of temperature, frequency and variation in interalkali concentration. AC conductivity at frequencies well beyond the dielectric loss peaks seems to arise from local motion of alkali ions within the neighbouring potential wells. Activation energies for AC conductivity were found to be very much lower than those for DC conductivity. Further, AC conductivity seems to be independent of interalkali variation, whereas ε′ and tan δ show a mild degree of mixed alkali effect. The observations made here have been explained on the basis of a structural model earlier proposed by us for these glasses.

    • Integral energy spectrum of primary cosmic rays at high energies

      R Hasan S C Arora D Hans M S Swami

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      The integral energy spectrum of primary cosmic rays has been obtained. In the energy range (2.4×103−1.1×105 GeV), the spectrum of all nuclei is consistent with a power law of indexγ=1.55±0.06 and the flux of all nuclei is:N(⩾E0)⋍(5.1±1.8)×10−1×E0−1.55 particles/cm2 sterad. sec., whereE0 is in GeV. The spectrum of primaryα-particles in the energy range (4.4×103−4.8×104) GeV is also consistent with a power law of indexγ=1.71±0.12 and the flux is:N(⩾E0)=(4.2±1.4)×10−1×E0−1.71, particles per cm2 sterad. sec, whereE0 is in GeV.

    • Motion of the charged particles off the equatorial plane of a Kerr black hole in an electromagnetic field

      D K Chakraborty A R Prasanna

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      Charged particle orbits off the equatorial plane of a Kerr black hole in an external electromagnetic field is studied, both for dipole as well as uniform magnetic field. Particles are found to get trapped by the magnetic field if the initial value of the parallel velocity is small. Bending of the field lines in the vicinity of the hole and the consequent trapping of the particles in an otherwise uniform magnetic field indicates the significance of general relativistic effects in such cases.

    • A microcomputer-controlled vacuum adiabatic calorimeter for the temperature range 4.2–300 K

      S Raman N S N Murty K Shivkumar Roy V Vasudeva Rao G Rangarajan

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      In this paper, we describe the operation of a vacuum adiabatic calorimeter controlled by a Rockwell AIM 65 microcomputer, which is suitable for specific heat measurements in the temperature interval 4.2–300 K. The system measures and calculates the specific heat and the results are printed out on a thermal tape. The cryostat, the electronic circuitry and the software are described. Results obtained using a pulsed heat technique on a specimen of high purity copper are given and compared with values reported in the literature.

    • When is a hidden variable theory compatible with quantum mechanics?

      M D Srinivas

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      This paper is devoted to a study of some of the basic conditions which have to be satisfied by a hidden variable theory in order that it can reproduce the quantum mechanical probabilities. Of course one such condition, which emerges from the important theorem of Bell, is that a hidden variable theory has to be non-local. It is shown that a hidden variable theory is also incompatible with the conventional interpretation of mixed states and the mixing operation in quantum theory. It is therefore concluded that, apart from being non-local, a hidden variable theory would also necessarily violate the usual assumption of quantum theory that the density operator provides an adequate characterization of any ensemble of systems, pure or mixed.

    • Dibaryons as six-quark states

      K Babu Joseph M N Sreedharan Nair V G Sreevalsa

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      In this paper we consider the experimentally observed dibaryons as six-quark states. The mass spectrum ofS-wave six-quark states is investigated in the recently developed variable pressure bag model. There is very good qualitative agreement between theory and experiment.

    • Supersymmetric solution of gauge hierarchy problem

      Romesh K Kaul

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      Some recent developments with respect to the resolution of the gauge hierarchy problem in grand unified theories by supersymmetry are presented. A general argument is developed to show how global supersymmetry maintains the stability of the different mass-scales under perturbative effects.

    • The quadrupole plus pairing interaction model in large configuration space for W, Os and Pt nuclei

      Ashok Kumar M R Gunye

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      The equilibrium deformations of tungsten, osmium and platinum nuclei are studied with the self-consistent quadrupole plus pairing interaction model by considering all the nucleons in nucleus explicitly. It is shown that similar results can be obtained by performing calculations with or without the assumption of an inert core. The only difference is in the strength of the quadrupole and pairing interactions to be employed in the respective calculations. The experimental static quadrupole moments and theB (E2) values are correctly reproduced by performing calculations with bare nucleon charge for all the nucleons.

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