• Volume 15, Issue 5

      November 1980,   pages  399-505

    • Description of ring puckering of furanose: An analytical approach

      N Pattabiraman V Sasisekharan

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      An analytical approach for the description of the ring puckerings from the endocyclic ring torsion angles of a five-membered saturated ring is given. This description is independent of any reference conformation. For the description, a revised notation for the endocyclic ring torsion angles has been suggested. The application of this method to the furanose ring is described in detail.

    • Effective potential for water vapour

      O M Singh A W Joshi

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      A suitable temperature dependence is introduced into the force parameters of the Lennard-Jones potential by taking the free-energy average of the Rowlinson potential. The resulting temperature-dependent parameters are used to calculate the effective potential, which is plotted for water vapour at a few different temperatures. The temperature-dependence of the second virial coefficient is shown for the cases of temperature-independent and temperature-dependent parameters of which the latter agrees very well with experimental results.

    • The C2II-X2Σ system of SrF molecule

      Ram Samujh Ram S B Rai K N Upadhya

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      The spectrum of the C2II-X2Σ system of SrF molecule has been investigated under high resolution. The rotational structure in the (0, 0) band has been analysed and the rotational constants for the C2II state have been obtained. The vibrational analysis of this system has been carried out using the band heads from the high resolution spectrogram and also the band origins and the precise vibrational constants have been reported for both the participating states.

    • Massless particles and cosmology

      Varun Sahni

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      Post recombination density perturbations have been studied in a two-component matter-radiation universe. The study has been carried out for variable matter and radiation densities. The possibility of the existence of different kinds of neutrinos in addition to the electronic, muonic and taonic has been considered and conclusions have been drawn as to the upper limit of the radiation density for different values of Ωm.

    • High spin yrast states in even platinum isotopes

      Ashok Kumar M R Gunye

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      The high spin yrast states up toJ=20+ in184, 186Pt and190, 192, 194Pt are studied in a microscopic approach of variation with number-conserved projected states. The energy spectra, quadrupole moments andB(E2) values are calculated by employing the Hamiltonian with quadrupole plus pairing interactions. The results of the calculations are in fair agreement with the available experimental data.

    • Microscopic band-mixing calculations in154,156Gd

      S V Moholkar C S Warke M R Gunye

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      A many-body microscopic band-mixing formulation of variation after projection of angular momentum and conservation of nucleon number is used to study the yrast band and first excitedKπ=0+ band in the doubly even nuclei154,156Gd. The computed energy spectra and the interband and intra-band B (E2) values are in good agreement with corresponding experimental data. Connection with the phenomenological model of Stephens and Simon is discussed, bringing out the role played by thei13/2 neutron pair in the microscopic formalism.

    • High energy proton-proton cross-section and Froissart bound

      R C Badatya P K Patnaik

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      A model for high energy proton-proton system is developed which obeys several asymptotic bounds including Froissart bound. The amplitude taken has two parts, a Regge part and a pomeron part. The Regge part is described by the exchange degenerate pairw andP′. To calculate the pomeron part the Freund-Harari duality is invoked which states that the pomeron is dual to thes-channel background. Thes-channel background is estimated by parametrising the branch cuts inS through a conformal mapping method. Expressions for total cross-section, ratio of real-to-imaginary parts of forward amplitude and the slope parameter are presented. The corresponding quantities for$$p\tilde p$$ are also evaluated. Our analysis favours strong exchange degeneracy.

    • Pressure-induced structural transformation in potassium stanichloride

      P Kistaiah K Sathyanarayana Murthy Leela Iyengar K V Krishna Rao

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      Pressure-induced structural transformation in potassium stanichloride has been studied by x-ray diffraction at room temperature. The change in the diffraction pattern started at about a pressure of 15 kbar and continued upto 50 kbar. The pattern recorded at about 50 kbar could be indexed basing on an orthorhombic lattice, with lattice parametersa=7.32,b=7.02 andc=8.02 Å.

    • Single-cavity 8 MeV race-track microtron

      V B Asgekar R K Bhalla B S Raye M R Bhiday V N Bhoraskar

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      This paper describes the operational details of the single-cavity race track microtron of this laboratory. The machine is capable of providing electrons of 8 MeV energy at 1 mA peak current. Important parameters of the machine and beam handling system are studied and the results are reported.

    • Pseudopotential study of lattice parameter and heat of formation for substitutional alloys

      S K Das D Roy

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      Ashcroft’s empty core pseudopotential is applied to the substitutional alloy (K-CS) to calculate the heat of formation and lattice parameter over the entire concentration range. At any concentration the defect crystal is considered to be equivalent to a perfect crystal with a modified lattice parameter and the potential parameter for the defect crystal is calculated by using some suitable interpolation formula. The calculated results agree well with the available experimental results.

    • Classical ϕ6-field theory in (1+1) dimensions 2. Proof of the existence of domain walls above the transition point

      S N Behera Avinash Khare

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      The existence of a domain wall-like contribution to the free energy above the first order phase transition point is demonstrated for a system described by the ϕ6-field theory in (1+1) dimensions.

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