Volume 27, Issue 3
September 1986, pages 363-483
pp 363-370 September 1986 Mathematical Physics
We consider here the problem of the existence of a quasi-invariant which is linear in the momenta for Hamiltonians in three degrees of freedom. We show that such quasi-invariants are more constrained in their structure than in the two degrees of freedom case. We also show that some of these quasi-invariants have to be interpreted as ‘pseudo-translations’, i.e., as translations in a non-orthogonal system of coordinates.
pp 371-382 September 1986 Particle Physics
Colour SU(3) symmetry is broken spontaneously by the introduction of coloured Higgs scalars in the standard SU(3)×SU(2)×U(1) model, so as to make the quarks integrally charged. The resulting couplings of the Higgs bosons with the gauge bosons are worked out.
pp 383-391 September 1986 Particle Physics
The complete expression of the five-dimensional Einstein-Hilbert action as an expansion in fields in the Appelquist-Chodos parametrization of the Kaluza-Klein metric has been given in this paper. It is explicitly shown that a unitary gauge can be fixed in which in each of the charge sectors the vector and the scalar fields are absorbed as Goldstone modes leaving behind the Pauli-Fierz Lagrangian for massive charged spin-2 field.
pp 393-400 September 1986 Nuclear Physics
A relatively stable method of phase shift analysis of hyperon-nucleon scattering proposed by us is applied to Σ+p and Λp scattering. The analytic cutt-planes of analyticity of the helicity amplitudes are mapped into the interior of unifocal ellipses. The helicity amplitudes are then expressed as accelerated convergent expansions in the mapped variable. A definite economy is observed in the number of free parameters for fixed energy phase shift analysis of Σ+p and Λp scattering at 40 and 100 MeV and 100 MeV respectively. Twenty six more phase shifts and coupling parameters corresponding to higherJ values are also predicted.
pp 401-408 September 1986 Atomic Physics
Positron annihilation and average energy in argon have been investigated in the presence of external high frequency electric and steady magnetic fields. The effect of temperature has also been studied. Two models of positron atom interaction have been employed and compared with experimental results wherever possible.
pp 409-412 September 1986 Atomic Physics
The triple differential cross-sections for the ionization of atomic hydrogen by fast electrons are considered in the case of a coplanar symmetric energy-sharing geometry. They are estimated in the modified Glauber (MG) approximation. It is found that MG results are significantly different from those in the second Born approximation only for 90°⩽ϑ⩽110°. Outside this range they are almost identical.
pp 413-416 September 1986 Instrumentation And Experimental Techniques
The construction and performance of an acoustic chamber suitable for sound intensity measurements is described. The walls and the ceiling of the room are treated with glass wool sheets, air gap and pleated carpet in that order for sound absorption. The final testing of the room shows that good sound absorption is obtained down to low frequencies. The sound absorption coefficient for the room varies between 0.83 and 0.91 for different frequencies.
pp 417-434 September 1986 Instrumentation And Experimental Techniques
This paper briefly describes the fundamental principles of the instruments used for accurate measurement of hydrostatic pressure and in particular the use of piston gauges as primary pressure standards. Different methods for the calibration of secondary standards have been discussed and in particular, emphasis has been given to the calibration of secondary piston gauges against the primary standards by the cross-float method along with the evaluation of uncertainties attached to different correction factors associated with the measurement of pressure from these gauges. The importance of secondary pressure standards in the region 0.1 GPa to several GPa has also been defined.
pp 435-441 September 1986 Plasma Physics
An enhanced spatial smoothing of ablative motion of thin plastic foil targets coated with high atomic number ablators such as gold or aluminium, irradiated by a spatially modulated Nd: glass laser beam was observed. Optical shadowgraphy coupled with double foil technique was used to observe the laser-irradiated foil motion. Laser irradiance used for the experiments was in the range of 1011–1013 watts/cm2. A 60–80% enhancement in the smoothing was observed for a laser beam modulation (width 75–150 µm) at the target surface.
pp 443-448 September 1986 Plasma Physics
The feedback suppression of flute instabilities by neutral beam injection is studied. It is shown that the available neutral beam current in mirror is sufficient to simulate the min-B field and thereby keep the flute modes in control.
pp 449-457 September 1986 Solid State Physics
The effect of pressure on the 2H and 4H polytype of PbI2 has been investigated by Raman and optical absorption spectroscopy, using the diamond anvil cell. The 2H-polytype undergoes pressure-induced phase transitions at 5 kbar and near 30 kbar. The 4H-polytype exhibits phase transitions near 8 kbar and above 30 kbar. The Raman modes abruptly change at these pressures. The optical absorption edge shifts red at the rate of 15±1 MeV/kbar in the 2H-PbI2 and at the rate of 7 MeV/kbar in phase II. The latter phase is most likely to possess a 3d-structure and not a layer type. The possible structures for the high pressure phases are discussed.
pp 459-468 September 1986 Solid State Physics
The influence of magnetic field on some switching parameters (turn-on time, turn-off time and amplitude of the current pulse appearing at base 1 terminal) of a unijunction transistor has been theoretically and experimentally investigated. The various switching parameters are shown to be governed by the magneto-concentration effect.
pp 469-474 September 1986 Solid State Physics
The thermal expansion coefficients of CsCl at eight different temperatures between room temperature and 90° K are presented. The lattice parameters obtained from the observed Bragg angles with the use of Bragg formula were extrapolated to 90° using the Nelson-Riley extrapolation scheme to minimize the systematic errors. The true lattice parameters thus obtained at each temperature were used to obtain the thermal expansion coefficients and these results are compared with earlier interferometric measurements.
pp 475-478 September 1986 Solid State Physics
The lattice parameters of CsBr at eight different temperatures from room temperature to 78.2 °K were measured and the true lattice parameters were obtained by the least squares method using the Nelson-Riley extrapolation function. Using these parameters the thermal expansion coefficients of CsBr were estimated at each temperature by fitting them into a cubic polynomial involving temperatureT. TheαT thus obtained were compared with the values of earlier workers who used an interferometric technique and the agreement was found to be good.
pp 479-482 September 1986 Letter
A scheme is presented for baryon asymmetry generation in early universe through monpole-induced baryon number violating processes in the context of a preonic model.
pp 483-483 September 1986 Erratum
Volume 93 | Issue 6
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