• Volume 60, Issue 6

      June 2003,   pages  1137-1307

    • Optimal entropic uncertainty relation for successive measurements in quantum information theory

      M D Srinivas

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      We derive an optimal bound on the sum of entropic uncertainties of two or more observables when they are sequentially measured on the same ensemble of systems. This optimal bound is shown to be greater than or equal to the bounds derived in the literature on the sum of entropie uncertainties of two observables which are measured on distinct but identically prepared ensembles of systems. In the case of a two-dimensional Hilbert space, the optimum bound for successive measurements of two-spin components, is seen to be strictly greater than the optimal bound for the case when they are measured on distinct ensembles, except when the spin components are mutually parallel or perpendicular

    • Bianchi-IX string cosmological model in Lyra geometry

      F Rahaman S Chakraborty N Begum M Hossain M Kalam

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      A class of cosmological solutions of massive strings for the Bianchi-IX space-time are obtained within the framework of Lyra geometry. Various physical and kinematical properties of the models are discussed

    • Renormalized energy-momentum tensor of λ Φ4 theory in curved space-time

      K G Arun Minu Joy V C Kuriakose

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      Divergenceless expression for the energy-momentum tensor of scalar field is obtained using the momentum cut-off regularization technique. We consider a scalar field with quartic self-coupling in a spatially flat (3+1)-dimensional Robertson-Walker space-time, having arbitrary mass and coupled to gravity. As special cases, energy-momentum tensor for conformal and minimal coupling are also obtained. The energy-momentum tensor is observed to exhibit trace anomaly in curved space-time

    • High-spin structure of neutron-rich Dy isotopes

      A Ansari H L Yadav M Kaushik U R Jakhar

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      In view of recent experimental progress on production and spectroscopy of neutron-rich isotopes of Dy with mass number A =166 and 168, we have made theoretical investigations on the structure of high spin states of164-170Dy isotopes in the cranked Hartree-Fock-Bogoliubov (CHFB) theory employing a pairingquadrupolehexadecapole model interaction. With the increase of neutron number the rotation alignment of the proton orbitals dominates the structure at high spins, which is clearly reflected in the spin dependence of the rotational g-factors. A particularly striking feature is the difference in the spin-dependent properties of166Dy as compared to that of164Dy

    • Ground state structure of some double-λ hypernuclei by a three-body model using a simple coordinate space approach

      S Mahapatra J Nag

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      New experimental data on the binding energyBλλ ofλλ6He, reported very recently, come up with the valuesBλλ = 725 ±0.14 MeV and ΔBλλ = 101 ±0.2 MeV which are substantially lower than the old dataBλλ = 109 ±0.8 MeV and ΔBλλ = 4.7±10 MeV in use in literature since 1966. In view of the new data we decided to undertake a re-study of theλλ6He hypernucleus using the same three-body model (α-λ-λ) with a simple coordinate space variational approach which was employed earlier with the old data onλλ/6He. After fitting different λ-λ potentials to the new data ofλλ6He we have applied our method to study some double-λ hypernuclei in light, medium and heavy mass regions and have determined the structural quantities like Bλλ, the r.m.s. values of core-λ (〈rcore-λ〉〉) and λ-λ (〈rλ-λ〉〉) distances theoretically. The core-λ interaction considered is of Woods-Saxon type. The strength and the range of the core-A potential have been adjusted to reproduce the λ-binding energy(Bλ). These are in good agreement with the relativistic mean field (RMF) results. Our study shows that the λ-λ bonding energy ΔBλλ decreases with increasing mass number fromλλ10Be toλλ210Pb of a double-A hypernucleus

    • Coplanar (e, 3e) differential cross-section of He atom

      R Choubisa A S Bhullar K K Sud

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      We present in this paper the results of our calculation of five-fold differential cross-section (FDCS) for (e,3e) process on He atom in low momentum transfer and high electron impact energy in shake-off mechanism. The formalism has been developed in Born approximation using plane waves, Byron and Joachain as well as Le Sech and correlated BBK-type wave functions respectively for incident and scattered, bound and ejected electrons. The angular distribution of FDCS of our calculation is presented in various modes of coplanar geometry and comparison is made with the available experimental data. We observe that the present calculation is able to reproduce the trend of the experimental data. However, it differs in magnitude from the experiment. The present theory does not predict four-peak structure insummed mutual angle mode for lower excess ejected electron energies. We also discuss the importance of momentum transfer, post-collision interaction (PCI) and ion participation in the (e,3e) process in constant θ12 mode

    • Energy and angular distributions of electrons ejected from CH4 and C3H8 under 16.0 keV electron impact

      S Mondal R K Singh R Shanker

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      Relative cross sections, differential in energy and angle, for electrons ejected from CH4 and C3H8 molecules under 16.0 keV electron impact have been measured. Electrons were analyzed by a 45° parallel plate electrostatic analyzer at emission angles varying from 60° to 135° with energies from 50 eV to 1000 eV. The angular distributions of electrons exhibit structures which are found to arise from Coulomb and non-Coulomb interactions. Furthermore, the double differential cross sections of electrons ejected from C3H8 molecule are found to be higher in magnitude than those from CH4. This result supports the fact that the number of ejected electrons participating in collisions with C3H8 molecules is more than that in CH4. Also, the angular distributions of C-K-shell Auger electrons emitted from the target molecules have been studied and shown to be isotropic within the experimental uncertainty

    • On the study of ion-acoustic solitary waves and double-layers in a drift multicomponent plasma with electron-inertia

      S N Paul S Chattopadhyaya S K Bhattacharya B Bera

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      Using the pseudopotential method, theoretical investigation has been made on the firstorder Korteweg-deVries ion-acoustic solitons in a multicomponent plasma consisting of warm positive ions, negative ions and isothermal electrons. The effects of electron-inertia and drift motion of the ions on the amplitudes and widths of the solitons have been studied in a plasma having (H+, Cl), (H+, O), (He+, H) and (He+, O) ions. Ion-acoustic double-layers have also been investigated for such plasmas. It has been found that drift velocity and electron-inertia have significant contribution on the formation of double-layers in multicomponent plasma

    • Lattice mechanical properties of some fcc f-shell metals

      J K Baria A R Jani

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      A pseudopotential depending on an effective core radius is proposed to study the binding energy, equation of state, ion-ion interaction, phonon dispersion curves (q-space and r-space analysis), mode Grüneisen parameters and dynamical elastic constants of some fcc f-shell metals La, Yb, Ce and Th. The contribution of the s-like electrons is calculated in the second-order perturbation theory for the potential while d and f-like electron is taken into account by introducing repulsive short-range Born-Mayer term. The parameter of the potential is evaluated by zero pressure condition. An excellent agreement between theoretical investigations and experimental findings is achieved which confirms the present formalism

    • Temperature dependence of dc photoconductivity in CdTe thin films

      Pradip Kumar Kalita

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      The temperature dependence of dc photoconductivity in the measuring range 303–417 K has been studied in CdTe thin films having thicknesst < 4000 Å. The photoactivation energy decreases in dark which is explained on the basis of grain boundary (GB) effect. The current lost to recombination at GB space charge region causes a negative effect on the photosensitivity of the films. A decrease in photosensitivity with increase in temperature is attributed to the reduction of photoexcitation process. It is observed that the minority carrier lifetime varies inversely with light intensity which supports the sublinear relationship of photoconductivity with the intensity of light and thereby confirms the defect-controlled photoconductivity in CdTe thin films

    • Rhythmic pattern formations in gels and Matalon—Packter law: A fresh perspective

      Jacob George Issac Paul P A Varughese George Varghese

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      The periodic precipitation pattern formation in gelatinous media is interpreted as a moving boundary problem. The time law, spacing law and width law are revisited on the basis of the new scenario. The explicit dependence of the geometric structure on the initial concentrations of the reactants is derived. Matalon—Packter law, which relates the spacing coefficient with the initial concentrations is reformulated removing many ambiguities and impractical parameters. Experimental results are discussed to establish the significance of moving boundary concept in the diffusion controlled pattern forming systems

    • Synchronized whistlers recorded at Varanasi

      Rajesh Singh Ashok K Singh R P Singh

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      Some interesting events of synchronized whistlers recorded at low latitude station Varanasi during magnetic storm period of the year 1977 are presented. The dynamic spectrum analysis shows that the component whistlers are Eckersley whistlers having dispersion 10 s1/2 and 30 s1/2. An attempt has been made to explain the dynamic spectra using lightning discharge generated from magnetospheric sources

    • On the effect of a longitudinal magnetic field on oscillatory characteristics of a subnormal region in discharge in argon

      D C Jana S S Pradhan

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      Oscillating nature of current pulses under d.c. excitation in subnormal region with longitudinal magnetic field at pressure range 0.20 torr to 0.85 torr have been studied. The frequency, bandwidth, peak-peak voltage, cut-off current and rise time of the current pulses have been observed with pressure, average tube current and magnetic field. A study of these oscillograms in magnetic field, average tube current and pressure are presented. The probable mechanism for the generation of oscillation based on space-charge field modification with magnetic field is discussed

    • Influence of the interplay between helicoidal magnetic ordering and superconductivity on the differential conductance in HoNi2B2C/Ag junctions

      I N Askerzade

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      The point contact spectra of magnetic superconductor HoNi2B2C/Ag-based junctions is analysed in the framework of Blonder-Tinkham-Klapwijk (BTK) theory. The anomalous behavior in the dI/dV curves above the Neel temperature(TN ∼ 5 K) is attempted to be explained by the partial suppression of superconducting gap parameter of the prevailing helical incommensurate structure

    • Subject Index

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    • Author Index

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