• Volume 41, Issue 2

      August 1993,   pages  1-191

    • Reply to the comment on ‘Modified perturbation series for the anharmonic oscillator using linearization technique’

      Nazakat Ullah

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      It is pointed out that the value of the perturbed energy calculated in the comment by Rath and Pattnayak, is incorrect. When the coupling parameter has the value unity, the energy up to second order of perturbation theory is 0.801 compared to its exact value of 0.804. The suggested split of the Hamiltonian into an unperturbed and perturbed part does not seem to be of any use as the unperturbed part contains anharmonic terms.

    • Resolved photon processes

      Manuel Drees Rohini M Godbole

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      We review high-energy scattering processes that are sensitive to the hadronic structure of the photon, describing theoretical predictions as well as recent experimental results. These processes include deep-inelastic electron-photon scattering ate+e colliders; and the production of jets, heavy quarks and isolated photons in the collision of real photons ate+e colliders, as well as in photon-photon collisions atep colliders. We also comment on minijet based calculations of totalγp andγγ cross-sections, and discuss the possibility that future lineare+e colliders might produce very large photon fluxes due to the beamstrahlung phenomenon; in the most extreme cases, we predict more than one hadronicγγ event to occur at every bunch crossing.

    • q-Deformation of algebraic structures of quantum and classical mechanics

      Debendranath Sahoo M C Valsakumar

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      There exists a coassociative and cocommutative coproduct in the linear space spanned by the two algebraic products of a classical Hamilton algebra (the algebraic structure underlying classical mechanics [1]). The transition from classical to quantum Hamilton algebra (the algebraic structure underlying quantum mechanics) is anħ-deformation which preserves not only the Lie property of the classical Hamilton algebra but also the coassociativity and cocommutativity of the above coproduct. By explicit construction we obtain the algebraic structures of theq-deformed Hamilton algebras which preserve the said properties of the coproduct. Some algorithms of these structures are obtained and their implications discussed. The problem of consistency of time evolution with theq-deformed kinematical structure is discussed. A characteristic distinction between the parametersħ andq is brought out to stress the fact thatq cannot be regarded as a fundamental constant.

    • Inflation driven by energy and curvature dependent bulk viscosity

      C Wolf

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      We study the relative rates of expansion in cosmologies admitting curvature dependent and energy dependent bulk viscosity. It is conjectured that curvature dependant bulk viscosity may be a phenomenological way of representing gravitational vacuum polarization around the time of the Planck era.

    • ΛΛ6 hypernucleus in α + 2Λ cluster model

      Mahmood Mian

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      The binding energy of the double hypernucleusΛΛ6 is calculated in α + 2Λ cluster model using the method of translation invariant basis TIMO. As regards the required interaction potentials we use a density dependent effective ΛN force and a gaussian form for ΛΛ potential. With these interactions a very reasonable value ofBΛΛ is obtained if the oscillator states up to the excitation quantum numberN=12 are taken into account in the expansion of wavefunction of the hypernucleus. This value ofN is much smaller than that obtained in an earlier study. This lowering inN value is attributed to a much better choice of ΛN potential used in the present study.

    • Deuteron-induced reaction studies of the nuclear structure of178Hf

      Raymond K Sheline Michael M Minor Prakash C Sood Dennis G Burke

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      The level structure of178Hf is interpreted on the basis of the population of the states following178Hf (d, d′),177Hf (d, p) and179Hf (d, t) reactions. Evidence for quadrupole and octupole vibrational bands and unmixed and intermixed two-quasiparticle configurations is presented.

    • Neutron flow or collective degrees of freedom for near barrier heavy-ion fusion

      S Kailas A Navin

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      Various models have been proposed in order to understand the near barrier heavy-ion fusion data. Amongst others the coupled channel approach of Dasso and Landowne and the neutron flow picture of Stelson are two of the mechanisms which describe well a large body of near barrier fusion data. From an analysis of16O induced fusion reaction around the barrier for various targets an attempt has been made to identify which out of the above two mechanisms is more appropriate to explain these data.

    • Momentum space distribution of electrons in an atom using hydrogenic wave functions

      Nazakat Ullah

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      A formulation is developed to derive exact analytic expressions for electron-electron correlation and density of electrons in momentum space using hydrogenic wave functions. It is shown that for large atoms the expression for density of electrons has a simple form.

    • L-shell/subshell ionization of Au, Pb and Bi by low energy proton impact

      K N Pandey D N Tripathi R N Chakraborty D K Rai

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      Proton induced X-ray emission has been used to measureL-subshell and total ionization cross-sections of Au, Pb and Bi in the energy range of 200–350 keV. The ionization cross-sections have been extracted using the X-ray spectra and other quantities like fluorescence yields, transition probabilities, relative widths and Coster-Krönig fraction etc. involved in the process. The results have been compared with the cross-sections measured before and discussed in the light of known theories regarding the ion-atom collisions.

    • Kinetic properties of an acoustic-like mode in a two-ion quasi-neutral plasma

      C B Dwivedi

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      Kinetic analysis of an acoustic-like mode in a plasma with hot and cold ion components has been carried out. Under the short wevelength approximation (De≫1), electrons are assumed to form a dynamic neutralising background and their contribution to the perturbation is neglected. The significant role of the hot ions to Landau damping of the acoustic-like mode is highlighted and a novel concept of plasma experiment is suggested.

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