bluuebunny/crossref_metadata_2025 huggingface dataset:
A positron study of plastic deformation of silicon
Authors: Dannefaer S. , Fruensgaard N. , Kupca S. , Hogg B. , Kerr D.
Published: April 2011

Positron lifetime and Doppler broadening experiments have been conducted in silicon which was subjected to various degrees of plastic deformation. With increasing plastic deformation (from 2.5 to 38%) the trapping rate per unit dislocation concentration decreased from about 8 × 1015 to 4.5 × 1015 s−1 as measured at room temperature. Two annealing stages were identified by isochronal annealing, one of which had an activation enthalpy of 3.2 to 3.8 eV as determined by isothermal annealing. Measurements in the temperature range 15 to 673 K show that the positron annihiliation parameters (lifetimes, intensities, and S-parameters) depend strongly on temperature and that the functional form of these dependencies is related to the state of annealing of the deformed samples. These results are disscussed in terms of the presence of vacancy clusters and dislocations, and evidence is presented indicating the existence of the hexavacancy.
μ− Conversion via doubly charged Higgs scalar
Authors: Picciotto C. E. , Zahir M. S.
Published: April 2011

A new mechanism is used to calculate μ− → e+ conversion in nuclei, based on the existence of a doubly charged Higgs scalar. The scalar is part of a triplet which generates the spontaneous breakdown of B–L symmetry in an extension of the standard model, as proposed by Gelmini and Roncadelli. We find a limit for conversion rates which is comparable with those of earlier calculations.
Renormalization scheme dependency and decoupling in the mass independent renormalization scheme
Authors: McKeon Gerry
Published: April 2011

The problem of renormalization scheme dependency that occurs when one employs mass independent renormalization is examined. In order to render this renormalization scheme viable in practical calculations, a way of decoupling heavy fields by demanding that the Appelquist–Carazzone theorem be satisfied at the outset is devised.
Cermets de Cu-PbI2 en couches minces: fabrication et détermination des constantes optiques
Authors: Theriault Jean-Marc , Boivin Germain
Published: April 2011

In this paper, we describe a method of fabrication of metal–dielectric mixtures (cermets) deposited by vacuum evaporation. Our study is mainly concerned with co-evaporated mixtures of copper and lead iodide. The stabilization of the evaporation rate of copper and lead iodide enables us to obtain a homogeneous mixture of these twø materials whose mass concentration C is determined from a previous calibration. Photometric measurements carried out on these films lead to the determination of the optical constants N (the index of refraction) and K (the coefficient of absorption). We present here the results obtained for mixtures of low concentration in copper. These results are compared with those obtained from the Maxwell–Garnett theory.
Rotational perturbations of Friedmann universes in Einstein zero mass scalar theory
Authors: Krori K. D. , Sarmah J. C. , Goswami D.
Published: April 2011

In an extension of a recent work by Bayin and Cooperstock, we investigate in this paper rotational perturbations of Friedmann universes in Einstein zero mass scalar theory. We find that except in the case of "perfect dragging", the zero mass scalar field has a damping effect on the rotation of matter. One of the three cases studied here shows that the scalar field may exist only during a certain interval in the course of the evolution of the universe. The zero mass scalar field has acquired particular importance recently because of a suggestion by Weinberg and Wilczek that there should exist a pseudo-scalar boson, the so-called axion, of negligible mass. The work of Peccei and Quinn has lent further support to the idea of axions.
2S Excitation of atomic hydrogen by electron impact at high energies
Authors: Saha N.
Published: April 2011

The 2S excitation cross section of atomic hydrogen by electron impact at high energies has been calculated following the method of Das. Comparison of the results for the differential cross section with other theoretical results, and comparison of the results for the total cross section with those of other theories and experiments, shows that the results of the present calculations are fairly accurate.
CCl+ (A1Π–X1Σ+, a3Π1–X1Σ+) emission systems produced from the thermal energy reaction between He+ and CCl4
Authors: Tsuji Masaharu , Mizuguchi Toshinori , Shinohara Keiji , Nishimura Yukio
Published: April 2011

Two emission systems of CCl+ have been observed by the dissociative charge-transfer reaction of He+ with CCl4 in the 230–255 and 390–405 nm region. The former system had been detected from an electronic discharge in CCl4 vapor, though the electronic transition had not been known definitely. On the other hand, the latter system was observed for the first time in this work. By comparison with spectroscopic constants obtained by ab initio calculations, the 230–255 and 390–405 nm bands were assigned to the A1Π–X1Σ+ and a3Π1–X1Σ+ systems, respectively. From the vibrational analysis of the a−X system, the following spectroscopic constants have been determined for the new state (in cm−1):a3Π,:Te = 25 480.6 ± 1.5; ωe = 1120.3 ± 1.0; ωexe = 7.52 ± 0.14. The mechanism of charge-transfer ionization leading to the CCl+ (A, a) states was discussed in comparison with that of electron-impact ionization.
On the nonsymmetric Jordan–Thiry theory
Authors: Kalinowski M. W.
Published: April 2011

This paper is devoted to a five-dimensional unification of Moffat's theory of gravitation and electromagnetism. We found "interference effects" between gravitational and electromagnetic fields which appear to be due to the skew-symmetric part of the metric of Moffat's theory. Our unification, called the nonsymmetric Jordan–Thiry theory, becomes the classical Kaluza–Klein theory if the skew-symmetric part of the metric is zero. The possible generalization to an arbitrary gauge group is discussed.
The effect of field geometry on electrodeless breakdown at 60 Hz
Authors: Curzon F. L. , Ma Rui-Lin
Published: April 2011

The electrodeless breakdown is produced in a gas-filled glass bulb by applying an alternating potential difference across two electrodes on opposite sides of the bulb. The dependence of the breakdown frequency on electrode voltage changes from linear to stepped-form as the size of the electrodes is decreased. A simple model, supported by experimental evidence, is presented to explain the effect.
Momentum characteristics of slow protons, deuterons, and pions in high energy interactions
Authors: Singh J. B. , Mittra I. S.
Published: April 2011

A detailed study of momentum and longitudinal momentum spectra of slow protons, deuterons, and pions produced in proton–emulsion (p–Em) interactions at 400 GeV, and π?p and π−C interactions at 40 GeV has been made. Striking differences in the results of different particles in both hadron–nucleon and hadron–nucleus interactions are obtained and the production mechanism of the particles is discussed.
Doppler-free two-photon absorption spectrum of cesium
Authors: O'Sullivan M. S. , Stoicheff B. P.
Published: April 2011

Doppler-free two-photon spectroscopy has been used to investigate the transitions n2S ← 62S (n = 9 to 54) and n2D3/2.5/2 ← 62S (n = 7 to 53), and saturated absorption for the quadrupole transitions 52D3/2.5/2 ← 62S. Wavelengths of these transitions have been measured to an accuracy of 1 part in 107, and term values, quantum defects, and fine structure splittings evaluated. Series formulae have been used with the term values to obtain the ionization limit 31406.6376 ± 0.0016 cm−1.
Dispersion of superconducting gap excitations in layered charge density wave systems
Authors: Mahanty G. C. , Behera S. N.
Published: April 2011

The phonon spectral function for charge density wave (CDW) systems in the superconducting (SC) phase is calculated for finite wave vectors (q). An exact expression for the q dependent phonon self-energy is obtained. The analysis is carried out with a small q limit. The spectral function shows a two peak structure for frequencies co less than the SC energy gap (2Δ) in contrast to the single peak obtained by Balseiro and Falicov for q = 0. The peaks approach each other with increasing q and finally merge into one. Both modes have linear dispersions for small q and the frequency of the low-lying one goes to zero as q → 0. For ω > 2Δ the phonon spectrum does not change significantly. The results are discussed in context with the Raman scattering observation of SC gap excitations in 2H–NbSc2 (a layered compound exhibiting both CDW and SC transitions) by Sooryakumar and Klein. The present calculation demands that the strength of coupling between the CDW phonon and SC electrons be an order of magnitude smaller than that used for q = 0 in order to get an agreement with the experimental result.
A quantization of the electromagnetic field
Authors: Capri Anton Z. , Grübl Gebhard , Kobes Randy
Published: April 2011

Quantization of the electromagnetic field in a class of covariant gauges is performed on a positive metric Hilbert space. Although losing manifest covariance, we find at the free field level the existence of two physical spaces where Poincaré transformations are implemented unitarily. This gives rise to two different physical interpretations of the theory. Unitarity of the S operator for an interaction with an external source then forces one to postulate that a restricted gauge invariance must hold. This singles out one interpretation, the one where two transverse photons are physical.
Frame dragging in Einstein and Einstein zero mass scalar cosmologies
Authors: Krori K. D. , Sarmah J. C. , Goswami D.
Published: April 2011

We investigate in this paper the perturbations caused by a spherical rotating shell in a closed homogeneous and isotropic cosmological model in Einstein and Einstein zero mass scalar theories. It is found from our solutions that in both theories the inertial frame at the origin is dragged with the angular velocity of the rotating shell during only a certain interval in the evolution of the universe when the shell covers the whole universe.
Experimental study of launched ion-acoustic waves in a plasma using continuous wave CO2 laser scattering
Authors: Brodeur P. , Andel H. W. H. Van , Schram D. C. , Glaude V. M. M.
Published: April 2011

A study of coherent density fluctuations in a low density plasma using continuous wave CO2 laser scattering diagnostics is reported. A simple and direct description of collective scattering theory from monochromatic electrostatic waves is presented. The diagnostic technique is described in detail and its performance is analyzed. Experimental results on externally launched ion-acoustic waves are presented and it is demonstrated that accurate measurements of certain plasma parameters are possible.
Développement complet du moment dipolaire des molécules tétraédriques. Application aux bandes triplement dégénérées et à la diade ν2 et ν4
Authors: Loete M.
Published: April 2011

Using a coupling scheme in the Td group, we determine all the vibration–rotation operators of the dipole moment of XY4 molecules up to any order of approximation. We give the matrix elements for these operators and general formulas for the calculation of the infrared transition intensities. This general formalism is available for any transition between vibrational sublevels of any symmetry. It can be used for the analysis of isolated bands and for the simultaneous analysis of interacting bands as well. We show that this method can be applied to the calculation of Raman intensities and to XY6 molecules.In some cases, it is possible to carry out a tensorial extension from the Td group to the O(3) group. We have constructed the operators of the dipole moment adapted to this process using a coupling scheme in O(3). In particular, we give the matrix elements for a triply degenerate band.We use the contact transformation technique to explain the parameters introduced in the formal expansion of the dipole moment. We define the contact transformation operators in a tensorial form. We apply this method in the case of the two interacting bands ν2 and ν4.
Méthode rigoureuse pour l'étude de la propagation des ondes électromagnétiques dans les guides périodiques
Authors: Amri Abdelkader , Chandezon J. , Cornet G.
Published: April 2011

The authors propose an exact method for studying electromagnetic propagation in perfectly conducting periodical waveguides with glide reflection symmetry. Maxwell's equations, written in a covariant form, are solved in a nonrectangular coordinate system in order to satisfy the boundary conditions. As a result, the dispersion (Brillouin) diagrams are given by the eigenvalues of a matrix which characterizes the waveguide, and the eigenvectors of this matrix determine the components of the electromagnetic field. Computed and measured results are compared for an "echelette" waveguide with glide reflection symmetry.
Analysis of the statistical S matrix generated in fitting 16O + 28Si elastic scattering
Authors: Hodgson R. J. W.
Published: April 2011

An S matrix, which gives very good fits for the elastic scattering of 16O + 28Si over the angular range 15° < θ < 180°, has been generated at six energies (21 MeV < E(centre of mass) < 35 MeV). The S matrix is composed of a parametric form plus a small statistical term for each partial wave. The properties of the S matrix have been examined in order to deduce the mechanisms involved in the reaction. The 180° excitation function has also been computed.
NQR study of the structural phase transitions in a system with reduced effective dimensionality: K2ReCl6
Authors: D'Iorio Marie , Armstrong Robin L.
Published: April 2011

Chlorine 35 nuclear quadrupole resonance (NQR) frequency and lineshape data, obtained with a Fourier transform magnetic resonance spectrometer, are presented for the antifluorite crystal K2ReCl6. In the temperature range investigated, 85 to 130 K, two structural phase transitions occur which reduce the crystal symmetry from cubic to tetragonal to monoclinic. The variation of the NQR spectrum with temperature and with hydrostatic pressure up to 2.64 kbar is documented. The structure of the spectrum and the intensity distribution within it are unexpected from previous studies of antifluorite systems. An explanation of the results is given which is based on recent discussions of nonlinear phenomena at phase transitions in crystals exhibiting reduced effective dimensionality.
Photoluminescence and optical absorption studies of the effects of heat treatment on cuprous oxide
Authors: Teh C. K. , Weichman F. L.
Published: April 2011

The defects responsible for the short-wave (720 nm) and medium-wave (820 nm) luminescence in cuprous oxide can be created by annealing the crystal at a temperature of 1050 °C under low oxygen pressures. The annihilation of these defects has been observed from the photoluminescence and optical absorption measurements after the crystal has been subjected to a second annealing in the temperature range of about 750 °C under a reducing atmosphere. From the photoluminescence measurements, the density of these defects is found to decrease exponentially as a function of annealing time, as manifested by the reduction in the luminescent intensity. The rate of reduction in intensity is also found to increase with annealing temperature.Because the defects responsible for the luminescence are ascribed to various forms of oxygen vacancies, we believe the decrease in luminescence is due to a reduction in the oxygen vacancies resulting from the formation of copper precipitates in the crystal. The short-wave and medium-wave emissions, which are ascribed to different types of oxygen vacancies, are found to have different activation energies of diffusion.
The ground state of an SU(2) gauge theory in a nonabelian background field
Authors: Parthasarathy R. , Singer M. , Viswanathan K. S.
Published: April 2011

The ground state in an SU(2) Yang–Mills theory using a constant nonabelian background field is studied taking into account the gluon and quark one-loop corrections to the classical energy density. The calculated energy density is found to be lower than that of the perturbative vacuum. The local minimum of the energy density is used to calculate the vacuum expectation value of the gluon condensate and the bag constant, which is found to be in reasonable agreement with the known estimates. The stability of this approximation is briefly discussed.
Aspects of the weak-coupling theory of open systems
Authors: Cox I. D. , Hagston W. E. , Holmes B. J.
Published: April 2011

Damping theory of an open system S is usually formulated in terms of projection operators which introduce nonuniqueness into the analysis. An insight into the nature of the approximations that arise from this aspect of the formalism is revealed by considering systems of varying complexity. This leads to the conclusion that the results of higher order perturbation theory approximations may not be meaningful.
Density effects on the translational motion from infrared induced rotational spectra of N2
Authors: Buontempo U. , Maselli P. , Nencini L.
Published: April 2011

Induced rototranslational absorption spectra of N2, measured at room temperature at different densities, are analyzed in order to derive the pure translational profile. Our analysis shows that the peak of the translational profile itself sharpens with increasing density while the tails broaden. Suitable parameters to describe the observed density effects are introduced and their density dependence is discussed in terms of a simple model.
A Monte Carlo and renormalization group study of the Ising model with nearest and next nearest neighbor interactions on the triangular lattice
Authors: Glosli James , Plischke Michael
Published: April 2011

The Ising model with nearest and next nearest neighbor antiferromagnetic interactions on the triangular lattice displays, for Jnnn/Jnn = 0.1, three phase transitions in different universality classes as the magnetic field is increased. We have studied this model using Monte Carlo and renormalization group techniques. The transition from the paramagnetic to the 2 × 1 phase (universality class of the Heisenberg model with cubic anisotropy) is found to be first order; the transition from the paramagnetic phase to the [Formula: see text] phase (universality class of the three state Potts model) is continuous; and the transition from the paramagnetic to the 2 × 2 phase (universality class of the four state Potts model) is found to change from first order to continuous as the field is increased. We have mapped out the phase diagram and determined the critical exponents for the continuous transitions. A novel technique, using a Landau-like free energy functional determined from Monte Carlo calculations, to distinguish between first order and continuous transitions, is described.
Anisotropic molecules forming a monomolecular layer on a strongly adhesive substrate: a scaled particle treatment
Authors: Banville M. , Caillé A.
Published: April 2011

Long chain fatty acids and large, rigid, aromatic molecules form a monomolecular layer on the surface of clean mercury. The surface pressure isotherms of these systems have been measured previously. In this paper, the scaled particle theory is applied to such monolayers with a number of simplifying assumptions. With a single adjustable parameter, the interaction of the molecules with the substrate and the general features of the surface pressure isotherms of the long chain fatty acids, anthracene, naphthalene, and cholesterol at intermediate liquid densities are fairly well reproduced.
Polarisation et mesures de section efficace dans la réaction 9Be(3He, p)11B
Authors: Pouliot J. , Roy R. , Bricault P. , Potvin L. , Slobodrian R. J.
Published: April 2011

New measurements of the differential cross section have been carried out in the reaction 9Be(3He, p)11B between 13.0- and 14.2-MeV incident energy. In order to compute the effective analyzing powers of polarimeters used to measure proton polarization in the same reaction, a precise knowledge of angular variations is necessary. The achieved accuracy allows a correct calculation of the false asymmetry caused by nonuniform illumination of the analyser from cross section variations.
Gas and liquid phase interactions at the chromium oxide cathode of a direct current arc discharge
Authors: Lange Hubert , Meubus Paul
Published: April 2011

The behaviour of a chromium oxide liquid sample has been studied in the presence of an argon arc discharge, the oxide being contained in a cathode crucible. The arc current was maintained at 24 and 44 A, at 21 V. The arc temperature distribution range was between 7 000 and 8 500 K, while the liquid oxide temperature stabilized at 2 420 or 2 620 K, depending on the arc current used. The reduced metal was obtained in the molten bath as a mixture with its oxide and was identified by X-ray diffraction.Using the Cr(I) 434.4-nm and Cr(I) 396.3-nm, as well as the Cr(II) 321.7-nm spectral data, it could be shown that a considerable part of the reduced chromium found at the cathode may originate from the arc discharge, migration of the Cr(II) species occurring under the effect of the electric field. The thermodynamic conditions in the cathode bath cannot explain the formation of Cr from the oxide decomposition in the bath. Also, in view of the low chromium oxide vapor pressure at the prevailing bath temperature, the mass transfer rate from the cathode bath to the arc should be increased by liquid oxide projection into the arc gas, under the effect of arc impact on the cathode. This should be followed by oxide evaporation and decomposition at high temperatures. This study confirms that the arc–cathode interaction may substantially increase the amount of oxide reduction at the cathode.
Anomalous magnetic moments for uncharmed and charmed baryons
Authors: Sagar Ram , Verma R. C.
Published: April 2011

We studied anomalous magnetic moments of the baryons using Drell–Hearn sum rules and found that the observed moments agree better in the presence of symmetry breaking effects.
Effets hyperfins induits par la vibration et la rotation moléculaire
Authors: Michelot F.
Published: April 2011

From the hyperfine Hamiltonian for a nondegenerate electronic state, we consider the determination, through a vibrational contact transformation, of the effective hyperfine Hamiltonian for an arbitrary set of interacting vibrational states. The cases of no accidental resonance and two level vibrational resonance are considered explicitly.
Critical temperature with paramagnetic and normal impurities under the square well model
Authors: Blezius J. W. , Carbotte J. P.
Published: April 2011

In the past, it has been shown that in superconductors where paramagnetic impurities are not involved, the results obtained from an analysis in the Eliashberg model with a square well approximation to the electron–phonon interaction are related simply to the analogous results of the Bardeen–Cooper–Schrieffer (BCS) model. The relation consists of a substitution of the mean square energy gap anisotropy for the mean square pairing potential anisotropy and of adding a (1 + λ) mass renormalization factor. The present paper considers a paramagnetic case in the same model and it is found that the relation to the BCS result is different from that of previously studied cases.
A new assignment for the 9/2+[624] state in 181Hf from the 179Hf(t, p)181Hf reaction
Authors: Burke D. G. , Waddington J. C. , Løvhøiden G. , Thorsteinsen T. F.
Published: April 2011

Angular distributions of protons from the 179Hf(t, p)181Hf reaction were studied using 15-MeV tritons from the McMaster University tandem Van de Graaff accelerator. The reaction products were analyzed with a magnetic spectrograph and detected with nuclear emulsions. Since the 179Hf target ground state is the 9/2+[624] orbital, a strong L = 0 transition was expected to the 9/2+[624] bandhead in 181Hf, which was previously assigned at 68 keV. However, the only L = 0 transition observed was to a level at an excitation energy of 600 ± 5 keV, requiring that this new level be assigned as the 9/2+[624] state. An attempt to observe gamma transitions deexciting this level in a (t, pγ) coincidence experiment yielded negative results. This implies that the 600 ± 5 keV level either has a half-life of [Formula: see text] or decays to an isomeric level by means of a low energy [Formula: see text] unobserved transition. The irregular spacing of possible 9/2+[624] band members suggests that the 11/2+[615] orbital is located near the 9/2+[624] state and perturbs the level spacing by Coriolis mixing.
On energy, entropy, and current in constitutive theory
Authors: Hajdo Leslie E.
Published: April 2011

The present article develops a linear constitutive theory for such materials as liquid crystals where stress, thermal, and electromagnetic effects, occurring interactively, are of potential interest. In the formulation of the theory, a novel view is taken of certain elements of electromagnetic energy and entropy. The results include a more satisfactory interpretation of current and dissipative heating in matter and a novel derivation of a comprehensive constitutive relation for charge flow in media.
Energy dependence of KNO moments using the Novero–Predazzi method with a new ansatz
Authors: Krasznovszky S. , Wagner I.
Published: April 2011

The method of Novero–Predazzi is applied to a new ansatz with three constraints. Hadronic production cross sections σn(s) satisfying Koba–Nielsen–Olesen (KNO)-like constraints are determined; σn(s) and [Formula: see text] automatically have the KNO scaling property. The multiplicity distribution Pn obtained is identical with the empirical formula used by Bozóki et al. The generalization of the method is investigated for more than three constraints. Assuming a given energy dependence of the parameter in the KNO function, we find that all calculated higher moments ck of the KNO function are in excellent agreement with the observed values of ck – s for proton–proton (pp) interactions at Serpukhov, the Fermi National Accelerator Laboratory (FNAL), and intersecting storage rings' (ISR) energies.A zero parameter empirical formula is presented, which gives good results at a 95% confidence level for pp interactions. This KNO function describes the multiplicity distributions e+e− at positron–electron tandem ring accelerator (PETRA) energies. We give a dynamical ansatz leading to this KNO function within the framework of a parton model.
Temperature dependent collision-induced absorption in nitrogen
Authors: Stone N. W. B. , Read L. A. A. , Anderson A. , Dagg I. R. , Smith W.
Published: April 2011

The collision-induced rotational translational spectrum of gaseous N2 has been measured in the temperature range 228–343 K at six different temperatures. The measurements were made with a Fourier transform spectrometer in the 25 to 360 cm−1 region and at 15.1 and 84.2 cm−1 with far infrared (FIR) laser. Previously obtained microwave data at 2.3 and 4.7 cm−1 have been used in defining the complete spectrum. Using a recently developed theory for quadrupolar-induced absorption, we find that the calculated quadrupole moment is independent of temperature and has a magnitude in close agreement with the recommended values of several other workers; i.e., Q = 1.46 B. The calculated value depends on the particular form of the intermolecular potential and this dependence is examined in some detail. A contribution to the absorption originating primarily from hexadecapolar and overlap induction has been observed in agreement with theoretical estimates and leads to an estimated value for the hexadecapolar moment [Formula: see text].
Quark-bag vibrations in heavy quark systems
Authors: Dey Mira , Tomio Lauro , Nogami Y.
Published: April 2011

Mulders et al. examined the consequences of bag vibrations in heavy quark systems and determined the upper bound on the inertia mass of the bag to be ~0.2 GeV by requiring the bag vibrational levels to remain above the observed four s-state levels in the upsilonium spectrum. We reexamine Mulders et al.'s model by taking full account of nonadiabatic effects which they ignored, and we essentially confirm their results. Implications of the upper bound of the inertia mass on the spectra of light quark systems are discussed.
Dynamics of the lower thermosphere consistent with satellite observations of 5577 Å airglow: II. Atomic oxygen, local turbulence, and global circulation results
Authors: Elphinstone R. D. , Murphree J. S. , Cogger L. L.
Published: April 2011

Satellite airglow observations in conjunction with a model for the photochemical and dynamical processes in the altitude range 80 to 120 km have been used to obtain the global and temporal variations of atomic oxygen concentration, eddy diffusion, and circulation. The concentration of atomic oxygen shows midlatitude peaks near equinox, and minima about one month after solstice. Average values at midlatitudes are about 1.3 times those at the equator. Small scale turbulence decreases away from the equatorial region in the postequinox period, while near solstice the turbulence is stronger and more uniform with latitude. At equinox, poleward meridional winds of 5–10 m/s are accompanied by upward winds at the equator and downward winds at midlatitudes. There is a slow transition from the dynamics occurring at equinox to those at solstice. At solstice, vertical wind velocities near 110 km of about 10–15 cm/s are upward in the summer and downward in the winter. About one month after solstice, the strength of global dynamics (both turbulence and circulation) reaches a maximum and the global atomic oxygen concentration is lowest. At this time a summer-to-winter flow occurs at high altitudes (> 110 km) accompanied by a return meridional flow below about 105 km.
High latitude ionospheric scintillations
Authors: Fulford J. A. , Forsyth P. A.
Published: April 2011

The statistical characteristics of ionospheric irregularities are often described by specifying one or two of the statistical parameters of the scintillations that the irregularities produce in satellite radio signals. The most commonly used parameter for this purpose is the spectral index (slope of the power spectral density function on a log–log plot). While it is becoming increasingly clear that the characterization of either phase or amplitude scintillations by a single parameter may obscure significant characteristics of the scintillations, this simple approach has proven to be useful for the prediction of the behaviour of transionospheric propagation paths such as those used in various space application systems. This paper explores the use, in addition to the usual phase and amplitude observations, of measurements of angle-of-arrival, in order to characterize the scintillations. Since each of these observations represent a different kind of observational "filtering", the combination of one statistical parameter from each type of measurement should provide a more adequate characterization of the scintillations. It is found that the use of the widths of the autocorrelation functions for this purpose is preferred over the use of spectral indices.
Superoperator methods for calculating cross sections. IV: Decoupled motions approximation
Authors: Turner Ralph Eric , Snider R. F. , Dahler John S.
Published: April 2011

A decoupled motions approximation to the time evolution of binary inelastic collisions is presented. The translational motion of the particles is described by a reference Hamiltonian while the internal motion is parameterized by the average trajectory associated with the translational motion. This description is applicable to both classical and quantum mechanics and any combination thereof. Thus it includes the standard impact parameter approximation. Cross sections for this decoupled evolution are derived from first principles. Explicit results for the impact parameter approximation are given.
Positive ion production in single collisions of Cl− with rare gas atoms
Authors: Hird B. , Rahman F.
Published: April 2011

The cross section σ−+ for double electron detachment from Cl− in a single collision with a rare gas atom has been measured between 12.5 and 122.5 keV. The magnitude of these cross sections shows that there is a good probability that a second electron will be emitted in collisions that detach one electron, particularly with light targets. The centre-of-mass cross section decreases with increasing target mass, but the variation is less than that for F− and O− double electron detachment cross sections.
Semiclassical calculation of the photoproduction of breather modes in the Sine–Gordon theory
Authors: Weiss Nathan , Mendel Eduardo , Berlinsky A. John
Published: April 2011

When a photon is incident on a 1 + 1 dimensional system described by the Sine–Gordon theory, transitions can occur from the ground state to soliton–antisoliton bound states called breather modes. We derive the lowest order Wentzel–Kramers–Brillouin (WKB) wave funetionals for these states and use them to estimate the transition rates. The transition to the lowest energy breather mode always dominates. The transition rates to the higher energy modes are suppressed by at least 10−2. A Monte Carlo simulation of the theory confirms this suppression. This effect is thus too small to account for the conductivity observed in the quasi-one-dimensional organic conductor tetrathiafulvene-tetraeyanoquinodimethane TTF-TCNQ.
Unspread wave packet in quantum mechanics
Authors: Bruce S. A.
Published: April 2011

The problem of the evolution in time of a quantum mechanical wave packet is restudied. A nondispersive wave packet is constructed considering appropriately the transformation rules associated with conveniently defined inertial reference frames.
Mean normalized shower multiplicity in inelastic hadron–nucleus interactions at high energies and multiparticle production mechanisms
Authors: Ghosh Dipak , Roy Java , Basu Madhumita , Sengupta Kaushik , Naha Sadhan , Banerjee Dipak
Published: April 2011

This paper presents a detailed comparison of the recent experimental data on mean normalized shower multiplicity in proton–emulsion interactions (22.6–400 GeV/c) with the predictions of current theories of multiparticle production in hadron–nucleus interactions. It has been observed that the data favour both the Fishbane–Trefil two-phase model (TEM) and the Fan diagram dominance model (FDDM) over a wide range of target nuclei, although the agreement with the FDDM seems to be better.
Spinor solutions to Maxwell's equations in free space
Authors: Hillion P. , Quinnez S.
Published: April 2011

Using the Hankel transform, we obtain, in their most general form, the spinor solutions of Maxwell's equations in free space for a light beam propagating along 0z with cylindrical symmetry around 0z. Then we compute a paraxial approximation of these solutions and we discuss the case of Gaussian beams. A comparison of the spinor solutions with the scalar ones supplied by the parabolic equation is also given.
All-multipolarity electric sum rule
Authors: Montgomery John A. , Überall Herbert , Yoo Kwang-Bock
Published: April 2011

An electric sum rule for photonnuclear and electron-scattering transitions, valid for all multipolarities greater than the monopole (L = 0) case, is derived. This sum rule, which includes both current and magnetization-induced transitions, is developed in the long-wavelength limit for isovector ΔT = 1 transitions. It is used to analyze nuclear charge–matter distributions for high multipolarity transitions in light nuclei.
Caractéristiques optiques de la photodécomposition de cermets et d'antireflets formes de Cu–PbI2
Authors: Boivin Germain , Theriault Jean-Marc
Published: April 2011

The fabrication of new thin film photosystems has led to the study of optical characteristics of photodecomposition in metal–dielectric mixtures (cermets) of Cu–PbI2. We report in this paper experimental results obtained for cermets of low volume concentration in copper. The photometric variations associated with those of optical constants induced by the photodecomposition of cermet are discussed and analyzed with respect to a possible optimization of their photographic properties. We also propose a new photosystem of optimum contrast that comprises a thin film of copper overcoated with a thin film cermet, both thickness being adjusted so that the whole system is antireflecting at λ = 632.8 nm.
Phonon anomalies in hexagonal close-packed transition metals using a model potential approach
Authors: Prasad M. V. N. Ambika , Gupta H. C. , Tripathi B. B.
Published: April 2011

We have investigated the phonon anomalies of titanium, zirconium, and hafnium by including the effective mass correction in the electronic contribution to the dynamical matrix. Good agreement between theory and experiment has been obtained for the phonon spectrum, and a satisfactory explanation of the softening of the [0001] longitudinal optic (LO) branch.
On the diffraction problem of a half plane with different face impedances
Authors: Lüneburg E. , Hurd R. A.
Published: April 2011

The problem of diffraction of a plane wave by a half plane with different impedance boundary conditions on opposite faces is considered. We show how it can be solved by a matrix factorization scheme and establish that the solution is identical to that obtained earlier by means of the Wiener–Hopf–Hilbert technique.
The triple differential cross section for the ionization of hydrogen atoms under electron impact
Authors: Ghosh A. S. , Mazumdar P. S. , Basu Madhumita
Published: April 2011

The triple differential ionization cross section (TDCS) in electron–hydrogen scattering has been calculated using a distorted wave polarized orbital method. The present TDCS results at 100 and 113.6 eV are in reasonable agreement with the measured values of Weigold et al. and the theoretical predictions of Smith. Winters, and Bransden.
Reply to comment: On the nonsymmetric Jordan–Thiry theory
Authors: Kalinowski M. W.
Published: April 2011

We reply to the comment by McKellar and discuss some details of the nonsymmetric Kaluza–Klein and Jordan–Thiry theories.
Photo- and electrodisintegration of few-body systems at intermediate energies: an introduction
Authors: Laget J. M.
Published: April 2011

The photo- and electrodisintegration of the two-nucleon system are reviewed. A diagrammatic method is discussed in view of its application to few-body systems and heavier nuclei. Its advantages and limitations are investigated.
The present status, recent experimental results, and future plans at the Tokyo electron synchrotron
Authors: Sumi Y.
Published: April 2011

The present status of the 1.3 GeV electron synchrotron at Tokyo is presented. First, we give a description of the experimental facilities and their characteristic features. Then the activities at the synchrotron are reviewed by focusing our interest on a few topics in the radiative processes of deuterons and other light nuclei. In particular, we show the latest data, as yet preliminary, on the reaction γd → π°d and on the photoemission of protons from light nuclei. Finally, we present future plans to improve the synchrotron capability, especially for photonuclear physics.
Radiative capture reactions in few-nucleon systems with polarized protons and deuterons at the Indiana University Cyclotron Facility
Authors: Hugi M.
Published: April 2011

A short progress report on radiative capture experiments at Indiana University Cyclotron Facility (IUCF) using polarized beam particles is presented. Some experimental details are outlined.
Longitudinal contributions to the vacuum polarization in the't Hooft–Veltman gauge
Authors: Mann R. B. , McKeon G. , Phillips S.
Published: April 2011

The Ward–Takahashi–Slavnov–Taylor (WTST) identities are examined in the 't Hooft–Veltman gauge ∂∙A + λA2 = 0. It is found that gauge invariance implies that there is a contribution to the longitudinal part of the vacuum polarization that is proportional to λ.
The free rotation of an equilateral triangle of protons
Authors: Stevens K. W. H.
Published: April 2011

The free and hindered rotation in a plane of a methyl group has recently been studied. Although the theory has been in existence for some time, errors were found in it. A similar theory exists for the rotation of methane, in three dimensions. It is desirable that the existing theory of this system should be re-examined, lest it too contain errors. As a step forward it seemed of interest to explore the extension of the recently developed method to methyl group rotation in three dimensions. The present paper gives an account of this extension, as a preliminary to treating the four-particle problem presented by methane.
Étude des corrélations entre paramètres de préparation, caractéristiques électriques et physico-chimiques d'échantillons de a-Si : H dopés ou non
Authors: Ranchoux B. , Currie J. F.
Published: April 2011

Using linear and second-degree regression, we have studied correlations between measurements of electrical conductivity, activation energy, concentration of the various elements (hydrogen, carbon, oxygen, argon, and eventually a dopant: indium, thalium, or antimony), thickness, and some preparation parameters: deposition temperature, mass flow ratio between the various gases intervening in the plasma, and deposition time. We have shown that the deposition rate is the only parameter, in the range studied, that plays an important role for the composition of the intrinsic films. The other parameters, viz. flow ratios of the various gases present in the mixture, temperature, have a limited influence on the composition and the electrical characteristics. The chemical composition measurements have been directly correlated with the electrical measurements. The introduction of a doping metal in the material modifies not only its opto-electrical characteristics, but generally its hydrogen content. Our process of doping by evaporation follows the "universal" behaviour of metals from columns II and V, already known in hydrogenated amorphous silicium. For the p and n films, we have observed that the hydrogen concentration and the width of the energy gap increase first with the dopant concentration and decrease afterwards. The presence of a dopant in the amorphous material leads to a disorder restructuring that changes the chemical composition more than the density of states in the energy gap.
Interlayer stacking structure in stage-1 graphite intercalation compounds of type MC6
Authors: Horie Chuji , Miyazaki Hiroshi
Published: April 2011

Intercalate interlayer stacking structures in stage-1 graphite intercalation compounds of type MC6 are studied within the framework of the mean-field lattice gas model. On the basis of the result obtained, the observed difference of the stacking sequences between LiC6 and otherMC6 compounds, M = Sr, Ba, Eu, and Yb, is discussed. In the latter cases, comment is made on the possibility of having order–order transitions associated with changes in the stacking sequences at low temperatures.
On the theory of the Stark shifts of the rotational–vibrational levels of the hydrogen molecule and its isotopes produced by a point charge. I: H2, D2, and T2
Authors: Poll J. D. , Hunt J. L.
Published: April 2011

The Hamiltonian describing the rotation and vibration of a homonuclear diatomic molecule in the field of a point charge at a fixed distance from its centre-of-mass is given. Numerical results for the Stark shift of the molecular levels due to a point charge of either sign are listed for H2, D2, and T2 as a function of the separation of the point charge from the molecule. The intensity associated with transitions between perturbed levels is discussed briefly.
Optical bistability in a small sample
Authors: Zaidi H. R.
Published: April 2011

A general formulation, developed earlier, is applied to the problem of optical bistability in a sample with dimensions that are small compared with the wavelength of light. A self-consistent model of radiative relaxation is introduced in which atom–atom correlations are taken into account. This is based on the screened interaction approximation of the many-body theory. The degree of correlation is internally determined by the dynamics of the system. The validity of the S-conservation approximation is investigated; it is concluded that this approximation may be valid only in the weak-field limit, since the local-field fluctuations become appreciable as the pump-field strength is increased. As a result, the system undergoes a first-order phase transition, in contrast to the second-order transition predicted by the S-conserving model. The method is quite general, and it can be applied to other damping mechanisms. As an illustration, a simple collision model is also considered. In the limit of a zero external field and thermodynamic equilibrium, our results reduce to the results of existing theories; the system exhibits a second-order phase transition.
Calculated frequency shifts in stimulated Brillouin backscattering from homogeneous plasmas with multiple ion species
Authors: Barnard A. J. , Bernard J. E.
Published: April 2011

The frequency shifts of the Brillouin backscattered lines from homogeneous plasmas, comprising more than one ion species, were calculated by solving the Vlasov dispersion relation. These frequencies can be an order of magnitude larger than those given by the fluid model. A method is given to calculate the frequency shift quickly and accurately for most applications.
Few-body binding-energy correlations
Authors: Kröger H. , Perne R.
Published: April 2011

Few-nucleon binding-energy correlations are discussed. The first-order correction in the propagator potential range ratio is estimated. The class of potentials is generalized from the previously considered rank-one separable potential. Similar results are predicted for few-atomic molecule clusters.
The apsidal motion of a binary star in the nonsymmetric gravitation theory
Authors: Moffat J. W. , Woolgar E.
Published: April 2011

The two-body post-Newtonian equations of motion in the nonsymmetric gravitational theory are reduced to the one-body form in the centre-of-mass coordinates. The periastron shift formula is calculated and an additional negative contribution is found that can have important consequences for apsidal motion in close binary systems.
Modulational stability of ion-acoustic waves using Karpman's method
Authors: Shivamoggi Bhimsen K.
Published: April 2011

Karpman's method is explored for the modulational instability of ion-acoustic waves on interaction with a slow plasma motion. The latter are found to be modulationally stable, unlike the Langmuir waves.
Nonlinear whistler wave – electron interaction in the presence of direct current electric fields
Authors: Das I. M. L. , Singh R. P.
Published: April 2011

The nonlinear interaction between an electron and a whistler wave propagating in a magnetoplasma has been studied and expressions for the resonance velocity, equilibrium relative phase angle, and the angular frequency of amplitude oscillations have been derived, taking into account the finite amplitude of the whistler wave, direct current electric field, and medium inhomogeneity. The parallel electric field and inhomogeneity cause detrapping of the particles.
Radiation solution of the modified Korteweg–de Vries equation
Authors: Enns R. H. , Rangnekar S. S.
Published: April 2011

An inverse scattering study of the radiation solution of the modified Korteweg–de Vries equation is carried out for a simple illustrative example. Specifically, extending the expansion approach (the reflection coefficient being expanded in powers of the area of the input potential) that we pioneered on the 3-wave interaction problem and recently applied to the study of sine-Gordon and sinh-Gordon dynamics, we obtain the complete spatial and temporal evolution of the modified KdV solution up to third order in the expansion. The solution and, in particular, its asymptotic (t → ∞) behaviour are discussed and a comparison is made with the asymptotic analysis of Ablowitz and Newell. The nonintegral contributions to the radiation solution are found to be in exact agreement as t → ∞ with Ablowitz and Newell's steepest descents approximation (evaluated for the same model) for the kernel of the Marchenko integral equation.