• Volume 44, Issue 6

      June 1995,   pages  489-568

    • Quantal behaviour of magnetically kicked electron

      A K Sikri M L Narchal

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      The problem of a free electron periodically kicked by a magnetic field has been solved. The system shows a transition from quantum recurrence to instability at ωT=2 where ω is the Larmor frequency andT is the period of the kick. The existence of recurrent behaviour amounts to the confinement of the electron by magnetic kicking. Since the theory holds for all types of charged particles, it has many practical applications.

    • Higher dimensional spherically symmetric inhomogeneous cosmological model with heat flow

      Subenoy Chakraborty Md Firoj Shah

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      We study spherically symmetric inhomogeneous cosmological model with heat flow in higher dimensional space-time and present a class of solutions in which the velocity field is shear-free. Some of these solutions are analogous to the known solutions in 4-dimension while some are totally new.

    • Supersymmetry in complex space-time

      Shuchi Bora B S Rajput

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      An interconnection between superluminal transformation and supersymmetric transformations has been investigated in complex C3-space and the evolution of bosonic and fermionic subspaces in such space has been undertaken. Introducing the suitable anticommuting operators to induce grading in Poincare group in C3-space in terms of components of complex angular momentum operator, the supersymmetric algebra connecting bradyonic and tachyonic bosons and fermions has been constructed and it has been demonstrated that the difference between scales of bosonic and fermionic subspaces in C3-space increases quickly in spite of their closeness initially.

    • Cosmic strings in Bianchi III spacetime: Integrable cases

      S D Maharaj P G L Leach K S Govinder

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      We investigate the integrability of cosmic strings in Bianchi III spacetime using a symmetry analysis. The behaviour of the model is reduced to the solution of a single second order nonlinear differential equation. We show that this equation has a rich structure and admits an infinite family of solutions. Our class of solutions extends special cases previously obtained by Tikekar and Patel [Gen. Relativ. Gravit.24, 397 (1992)].

    • Static and dynamic properties of pseudoscalar mesons

      D K Choudhury Pratibha Das D D Goswami J K Sarma

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      We report the results of form factors, charge radii and decay constants of both light and heavy flavoured pseudoscalar mesons in a QCD inspired quark model. We use the quantum mechanical perturbation theory and discuss its limitations in the present problem. Several predictions are also made for bottom and top flavours.

    • Measurement and analysis of alpha particle induced reactions on gold

      D J Shah H B Patel N L Singh S Mukherjee S N Chintalapudi

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      Stacked foil activation technique and Ge(Li) gamma ray spectroscopy have been used for the measurement of excitation functions of197Au(α,xn) (x=1−3),197Au(α,2pn) and197Au(α,αn) reactions up to 50 MeV. The experimental cross-sections were compared with the predictions of pre-equilibrium hybrid model, as well as with the more recent index model. A general agreement was found in all reactions using initial exciton numbern0=4(4p0h) except for197Au(α,n) reaction, where index model gives fairly good agreement withn0=5(5p0h).

    • Elastic scattering of 81 keVγ rays by aluminium, nickel, tantalum, gold and lead

      G Basavaraju P P Kane Lynn Kissel R H Pratt

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      A recently reported study [Phys. Rev.A49, 3664 (1994)] of elastic scattering of 81 keVγ rays in the angular range from 60° to 133° has been extended to smaller and larger angles. Previously reportedS matrix calculations of atomic Rayleigh scattering have been shown to require a subtraction of contributions from spurious resonances. Most of the experimental data are in agreement with the calculations. Calculations (MF + ASF) based on a combination of relativistic modified form factors (MF’s) and angle independent anomalous scattering factors (ASF’s) are found to be inadequate for an explanation of experimental cross-sections in the case of highZ elements at angles larger than about 120°.

    • Collision cross-sections for scattering of electrons from NO molecule

      Arvind Kumar Jain Pradeep Kumar A N Tripathi

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      Electron-NO scattering is investigated in the energy range 2–1000eV by using a parameter-free spherical complex optical potential (SCOP) approach in the fixed nuclei approximation. The real part of the optical potential consists of three potentials namely, the static, the exchange and the polarization. For the imaginary part of the SCOP, we employ a semi-empirical model absorption potential. The molecular charge density function is calculated from a single-configuration molecular orbital based on Slater type orbitals. The various potential terms are then determined from these charge density functions. Calculations of the elastic (with and without absorption effects), total absorption, momentum transfer and differential cross-sections are obtained and compared with the available theoretical results and experimental measurements.

    • Electron impact ionization of Ba, Ba+ and Ba2+

      Gopaljee S K Shrivastava B N Roy

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      The binary encounter approximation has been used to investigate the effect of charge state of the target atom (ion) on the electron impact excitation autoionization cross-sections. Roothan-Hartree-Fock (RHF) velocity distribution for the bound electrons has been used through-out the calculations. The present results give a good account of the experimental observations.

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