• Volume 13, Issue 1

      July 1979,   pages  1-95

    • A simple and inexpensive two channel boxcar integrator

      R K Shenoy J Ramakrishna K R Jeffrey

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      A two-channel boxcar integrator with an analog to digital converter was constructed using integrated circuits wherever convenient. The digital output can be instantaneously displayed or displayed after accumulating many samplings in the totaliser. The totaliser mode provides averaging at the digitiser level and hence the integrator has an infinite holding time. When used in the double boxcar mode the instrument overcomes the problem of any base line instability.

    • On the summation of the Brillouin-Wigner type perturbation series

      K V Sane R P Saxena P K Srivastava

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      It is shown that if the ‘mean excitation energy’ assumption is introduced in the Brillouin-Wigner perturbation series, then the resulting series can be exactly summed. The implications of the result for calculating energy shift and for constructing trial functions are examined with special reference to the ground state of the helium atom.

    • Scattering contributions to the internal partition function of a diatomic molecular system

      B Talukdar M Chatterji P Banerjee

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      An analytical expression for the phase shift contribution to the internal partition function for the Morse potential is derived by using an approximate Jost function. This function is shown to be a convergent sum. The numerical results obtained for H2 and HCl show the partition function to be a monotonically increasing function of temperature. This observation agrees with the results of Rogers and co-workers.

    • Response of photosensitive silver halide micro-crystals to multiple-charged particles

      Mahendra Singh A P Sharma

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      Temperature dependence of sensitivity of silver halide micro-crystals is theoretically examined for a wide range of momenta and charges of ionising particles. Our earlier results on the ionisation theory have now been extended for the interaction of multiple-charged particles with AgBr emulsion grains.

    • Interionic forces in AgF, AgCl and AgBr crystals

      V C Jain Jai Shanker

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      An interionic force model has been used in which the short range nearest neighbour and the next nearest neighbour repulsive interactions and the van der Waals’ interactions are balanced by the long range electrostatic forces. The nearest neighbour and the next nearest neighbour interactions are derived from the overlap integrals for outer shell electrons. The van der Waals’ interactions are estimated from the Slater-Kirkwood variational method. The cohesive energy, the bulk modulus and its pressure dependence for AgF, AgCl and AgBr crystals have been calculated and compared with experimental data.

    • Theoretical study on the behaviour of metal-p-n-Si Schottky barrier solar cell

      G S R Krishna Murthy A P B Sinha

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      The performance of Au-p-n-Si Schottky barrier solar cell has been investigated theoretically following Li’s work on GaAs. The behaviour of the barrier height as a function of carrier densities in then andp regions and thep layer thickness is investigated. The photovoltaic cell characteristics are worked out and conditions for maximum efficiency obtained.

    • Effective operators and the truncation of shell model configuration space

      Y K Gambhir G Basavaraju

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      An alternative derivation of the projection method for constructing effective operators in the truncated shell model space is presented. The results of explicit numerical calculations in three different nuclear regions are discussed. Non-hermiticity of the effective Hamiltonian and various hermitisation procedures are investigated in detail.

    • Uniqueness of the standard model neutral current predictions

      S K Soni

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      In view of an excellent agreement between the recently determinedvμ-hadron couplings and predictions of the standard model, the basic question discussed is how far its neutral current predictions can be mimiced in going either from the isodoublet to an isotriplet (or an even higher isospin) left-handed representation or from SUL (2) × U(1) toG × U(1), whereG is a simple group of rank two. This question is addressed with reference to a sufficiently broad class of schemes. Their most distinctive properties are: in the higher isospin scheme, neutrino couplings are precisely in the form obtainable with standard l.h. representation; the higher g.g. scheme isL+R type in which, to each light fermion of evenRU parity, a superheavy fermion of the same charge and oddRU parity is associated, parity conservation forbidding their mixing. Reasons for excluding theL-type andG2 higher g.g. schemes are given. Their neutral current predictions are compared with those of the standard model. A higher isospin representation can mimic the predictions of the standard model in inclusive and semi-inclusivevμ-hadron reactions but is conclusively discriminated from the isodoublet representation by elasticvμ(−p scattering. TheG × U(1) scheme can mimic standard model neutrino sector but is conclusively discriminated from minimal scheme by parity violating effects.

    • A model for multiparticle production in high energy hadronic collisions

      T Aziz M Zafar

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      A model for multiparticle production process in high-energy hadronic collisions is proposed. In the centre of mass (CM) system of colliding particles the target and the projectile are assumed to pass through each other sharing energies allowed by kinematical constraints. Thus in app collision the energy associated with each is √S/2 (S being the square of the CM energy) which is taken to be the real variable that governs the number of particles produced. In the case of hadronnucleus collisions the projectile and the target ofv nucleons lying in a (Lorentz contracted) tube pass through each other sharing energies ⋍ √SA2, whereSAvS. Before the final state particles emerge from these systems, the constituents of the target, i.e.,v nucleons share equally (= √SA2v) the total energy associated with the target and become the centres from which final state particles stem out. Several results have been discussed.

    • Comparison of eikonal-Born series and modified Gluaber approach for the study of elastic electron-hydrogen scattering

      S S Tayal S N Singh A N Tripathi

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      Elastic electron-hydrogen scattering at medium and high energies has been analysed in eikonal-Born series and modified Glauber approach forEi ≥ 50 eV. We have used closed form expressions for evaluating the second Born term in the fixed scatterer approximation and for higher order terms of Glauber-eikonal series. The exchange effect has also been included via Glauber-Bonham-Ochkur type procedure. The fixed scatterer approximation calculations are compared with results obtained using other approximations for the second Born term available in the literature. The results compare fairly well with experimental data.

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