Volume 23, Issue 1
July 1984, pages 1-118
pp 1-16 July 1984 Plasma Physics
Experimental results on interaction of a rotating relativistic electron beam with plasma and neutral gas are presented. The rotating relativistic electron beam has been propagated up to a distance of 150 cm in a plasma. The response of the plasma to the rotating electron beam is found to be of magnetic diffusion type over a plasma density range 10^{11}–10^{13} cm^{−3}. Excitation of the axial and azimuthal return currents by the rotating beam and subsequent trapping of the azimuthal return current layer by the magnetic mirror field are observed. A field-reversed configuration has been formed by the rotating relativistic electron beam when injected into neutral hydrogen gas. We have observed field reversal up to three times the initial field in an axial length of 100 cm.
pp 17-29 July 1984 Solid State Physics
Electrical transport and high pressure studies on bulk Ge_{20}Te_{80} glass
G Parthasarathy A K Bandyopadhyay S Asokan E S R Gopal
The electrical resistivity of bulk Ge_{20}Te_{80} has been measured as a function of pressure and temperature. At 5 GPa, an amorphous semiconductor-to-crystalline metal transition has been observed. The sample recovered from the high pressure cell, after the application of 7 GPa, has a face-centred cubic structure with a lattice constant of 6·42 A. In crystalline sample, the semiconductor-to-metal transition occurs at 7 GPa. The thermoelectric power has also been measured for glassy samples in the temperature range 300–240 K.
pp 31-37 July 1984 Solid State Physics
Pressure-induced electronic and structural transformations in bulk GeSe_{2} glass
M V N Prasad G Parthasarathy S Asokan E S R Gopal
The pressure dependence of the electrical resistivity of bulk GeSe_{2} glass shows a semiconductor-to-metal transition at 7 GPa pressure. The high pressure phase is examined using the x-ray diffractometer and is found to be crystalline, with a face-centred cubic structure havinga = 4·06 A. The electrical conductivity has also been studied as a function of temperature at various pressures.
pp 39-46 July 1984 Solid State Physics
Validity regions of charge shift model
The charge shift model has been used to calculate electric field gradients (efg) for various probe-host combinations. The comparison with the corresponding experimental values indicates that the validity of the model depends on sign and magnitude of the charge shift. The model agrees fairly well with experiments for the hosts having positive charge shift. The agreement is good for hosts having negative charge shift only if the magnitude is small (< 0·012).
pp 47-52 July 1984 Liquid State
Critical properties of nitrobenzene solutions by electric conductivity method
Electric conductivity of nitrobenzene soluted inn-hexane,n-heptane andn-octane was studied in constant and alternative field. Phase coexistence curves were determined together with the critical temperature, critical concentration and critical exponentβ for each of the systems. The measurements were performed in the temperature rangeT_{s} <T < (T_{s} + 10)K and for the concentrations of nitrobenzene between 0·2 ≲x_{2} ≲ 0·7 molar fraction.
pp 53-57 July 1984 Liquid State
Anomaly in electric resistance of binary liquids near the critical point
Electric resistance in critical solutions of nitrobenzene inn-hexane,n-heptane andn-octane was measured. The resistance near the critical point was studied and divergence in the temperature derivative measured.
pp 59-68 July 1984 Liquid State
Optical transitions of Eu^{3+} ions in EuCl_{3} solutions
The optical absorption spectra of EuCl_{3} in aqueous and acidic solutions were measured in the visible anduv regions of the spectrum. The concentration as well as the temperature of the solutions were varied to establish an accurate free-ion energy level scheme of Eu^{3+}. The energy levels were assigned on the basis of a correlation between the calculated and the experimentally observed transition energies and associated band intensities.
pp 69-77 July 1984 Statistical Physics
Light scattering from a nonequilibrium fluid undergoing a planar Poiseuille-Couette flow
We calculate the Rayleigh-Brillouin spectrum of a Newtonian fluid undergoing a planar Poiseuille-Couette flow using the fluctuating hydrodynamic approach of Landau and Lifshitz. Our results reduce to the corresponding results for pure Couette flow when the pressure gradient is made to vanish. The Brillouin spectrum is obtainable from that appropriate to Couette flow by a simple rescaling. There are very minute corrections which impart asymmetry to the Brillouin lines as well as the Rayleigh line, and these can be selectively picked up by suitable choice of the scattering geometry.
pp 79-90 July 1984 Statistical Physics
Thermodynamic properties of a two-dimensional square-well fluid
Analytic expressions for the thermodynamic properties of a classical two-dimensional square-well fluid and the first quantum correction to them are derived using the Barker-Henderson perturbation theory. Numerical results are reported. It is found that the quantum effect, which increases with increase of density, is largely determined by the hard-core and the attractive tail has a minor effect at high density.
pp 91-97 July 1984 Nuclear Physics
Phase shift analysis of pion-^{4}He scattering by optimal polynomial expansion
A novel method of phase shift analysis for the scattering of charged pion from^{4}He nuclei is proposed. The nuclear amplitudef_{N}(ϑ) has been parametrized in terms of a polynomial expansion in a conformally mapped variable, which is obtained by optimally exploiting the analytic property off_{N}. The method exhibits a significant reduction in the number of free parameters required for the fixed energy phase shift analysis of the differential cross-section data. The nuclear amplitude thus constructed is then used to obtain phase shifts and inelastic parameters of all possible orders. Reliable values of the real and imaginary parts of the forward amplitude are also obtained.
pp 99-107 July 1984 Particle Physics
Recoil corrections to magnetic moments of charmed baryons in themit bag model
Recoil corrections to magnetic moments of charmed baryons are studied in themit bag model. It is noticed that such corrections which improve the octet baryon magnetic moments have considerably significant contributions to charmed baryon’s moments also.
pp 109-118 July 1984 Particle Physics
Nonleptonic decay matrix elements in the variable pressure bag model
The consequences of the variable pressure bag model for the nonleptonic decays of hyperons and Ω^{−} are investigated. Though the order of magnitude and the relative sign for the various decay amplitudes are correctly reproduced, the overall results are small by a factor of 2 to 4, indicating that the theoretical predictions are strongly dependent on the model parameters.
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