• Volume 12, Issue 1

      January 1979,   pages  1-101

    • The resolution of a paradox which arises in the elementary discharge theory of an ion source

      R Jones

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      It is shown that the inclusion of a small amount of primary ionisation makes the solution to the discharge equilibrium problem single valued.

    • The short range interactions between two rare gas atoms

      K L Sebastian A K Chandra

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      The short range interactions in He2, Ne2 and Ar2 have been studied in terms of the electronic forces as functions of their internuclear separations employing their single configuration SCF wave functions. The results show that the constituent molecular orbitals behave differently in terms of the forces they exert on the nuclei during the interaction process. The different behaviour of the orbitals is also reflected in the redistribution of charges.

    • Pre-irradiation effect on the defect formation in CdS-Ni subjected to electrodeless discharge

      P D Ekbote J K Zope

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      Samples of CdS: Cu, Pb were subjected to electrodeless discharge wherein the samples washed with Ni nitrate solution showed different absorption peaks near the absorption edge as compared to the samples which were previously irradiated, washed with Ni nitrate solution and again irradiated.

    • Theory of melting, vacancy model

      S N Vaidya

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      A theory of melting based on vacancy model is formulated. The polymer solution theory is used for derivation of the melting equation for a two-species model of melting solid. Under simplifying assumptions the analysis leads to a simple correlation betweenTm and 〈v〉, the average energy of interaction between the vibrating atoms. Pseudopotential method is used for calculating 〈v〉 for the alkali metals lithium, sodium, potassium and rubidium at temperatureTm. The calculated values ofTmv〉 are in accord with those expected from our model. Application to the high pressure melting curves of solids is also discussed.

    • Characteristics of high energy interactions I. High energy gamma-ray spectra near the top of the atmosphere

      R Hasan A K Agrawal M S Swami

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      An emulsion chamber was used to study the characteristics of high energy nuclear interactions from the production spectra ofγ-rays. The emulsion chamber, which comprised of two parts, namely the detector and the graphite producer unit, was exposed to cosmic rays for about 7 hr at an atmospheric depth of 10 g cm−2 at Hyderabad (geomagnetic latitude 7·6°N). 720 electromagnetic cascades due toγ-rays were recorded in the detector. These cascades were classified into three groups; (a)γ-rays from nuclear interactions in the detector (b)γ-rays from nuclear interactions in the producer unit and (c)γ-rays of atmospheric origin. The energies of the cascades were determined using photometric method. The spectra ofγ-rays from groups (a) and (c) were determined and compared with similar spectra obtained at greater atmospheric depths. The spectra were found to obey a power law. The spectrum ofγ-rays of atmospheric origin was found to steepen at high energies,Er>2200 GeV.

    • Characteristics of high energy interactions II. Production spectra of Gamma-rays in graphite

      A K Agrawal R Hasan M S Swami

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      Twenty high energy nuclear interactions produced in the graphite units of an emulsion chamber were recorded. The emulsion chamber was exposed to cosmic rays at an atmospheric depth of 10 g cm−2 for about 7 hr over Hyderabad, India. Fourteen interactions which radiated energyΣ Er⩾1000 GeV in the form ofγ-rays were analysed in detail. The median energy 〈Σ Er〉 of the interactions was 1600 GeV. Results concerning the multiplicity, the transverse and longitudinal momentum distributions, and the fractional energy distribution ofγ-rays in these interactions are presented. The average transverse momentum ofπ0—mesons <ptπ0> is found to increase very slowly with the primary energyE0 and it can be approximated by the function <ptπ0>=0·238E00.06.

    • Weak nonleptonic decays of 3/2+ isobars in SU(3)

      Kusum Sharma Ramesh C Verma

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      Weak transitions of decuplet isobars are expanded in terms of eigen-amplitudes of the direct channel in the framework of SU(3). Starting with the most general weak Hamiltonian and assuming intermediate states to be non-exotic, we obtain ΔI=1/2 rule for Ω decays. Invoking of the CP invariance forbids all thepv weak processesD(10)→D(10) +P(8). Decays of the charmed multiplets are also discussed in these dynamical considerations. We obtain triplet dominance of charm changing weak Hamiltonian for Ω*++3 decays.

    • Connection between elastic scattering and inclusivekT2 distribution

      D S Narayan K xxxV L Sarma

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      A connection between the elastic scattering and the inclusive one-particlekT2 distribution is pointed out in the context of thes channel unitarity. One of the implications of this connection is that the slope of thekT2 distribution atkT2=0 is about a factor two larger than the slope of the elastic scattering att=0.

    • Colour effects in Drell-Yan process

      P N Pandita Sudhir Paranjape

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      We examine the predictions of gauge theories with colour excitation for the processppμ+μX. Relative to the predictions of quark parton model (with three colours) we find enhancements as large as a factor 3 – 4 for the cross-sectionM3d2σ/dMdy|y=0 in the region 0·03 ≲M/√s ≲ 0·2 at √s=62 GeV,M being the invariant mass andy the rapidity of the muon pair. We study the sensitivity of this result to the colour gluon mass and the underlying parametrisation of the quark and gluon distribution functions.

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