bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of mixing ratios for some cascades corresponding to 109Ag
Authors: Bosch H. E. , Silbergleit V. M. , Davidson M. , Davidson J.
Published: April 2011

An investigation of the gamma–gamma ray angular correlations following the decay of 109Pd was made by using a Ge(Li) semiconductor counter and NaI(Tl) gamma-ray detector. Coincidences measurements at six different angles were made between the 311 keV gamma ray (gated in the movable counter) and 390, 413, 424, 551, and 558 keV gamma rays (displayed in a multichannel analyzer (MCA)). Chance coincidences as well as coincidence background were taken into account. The following spins and mixing ratios were determined: 701 keV level 3/2, δ(390) = 0.19 ± 0.06; 724 keV level 3/2, δ(413) = 0.18 ± 0.05; 735 keV level 5/2, δ(424) = −0.27 ± 0.03; 862 keV level 5/2, δ(551) = −0.28 ± 0.04; 869 keV level 5/2, δ(558) = −0.26 ± 0.05. The result indicates that the anisotropies are consistent with mixing ratios less than 28% in all cases.
Small angle polarimetry
Authors: Karl Gabriel , Hunt J. L.
Published: April 2011

We will discuss anew method for the measurement of very small angles (less than 10−2 rad) of rotation of the plane of polarization of radiation. The method consists of a large amplification, by several orders of magnitude, of the angle to be measured, prior to its measurement by conventional means. The gain in angle is at the expense of the intensity of the detected beam.
Precise single neutron separation energies of Ti, Fe, and Zn
Authors: Barnard J. W. , Williams P. , Barber R. C. , Haque S. S. , Kozier K. S. , Sharma K. S. , Duckworth H. E.
Published: April 2011

Six precise single neutron separation energies have been derived from doublets determined using Manitoba's 2.73 m mass spectrometer. In addition, Manitoba's 1 m instrument has been used to corroborate certain of these new values. The new Sn values, which are generally in good agreement with precise nuclear reaction data, are accurate to 0.9 keV or better. These values may be suitable as calibration standards for nuclear reaction studies in the 5 to 10 MeV region.
Shell-model calculations of the far-infrared optical properties of CsI
Authors: Eldridge J. E. , Howard Roger , Staal P. R.
Published: April 2011

The far-infrared optical properties of CsI, including the real and imaginary dielectric constants, absorption coefficient, refractive index, and reflectivity, have been calculated absolutely using shell-model lattice-dynamical data, fitted to dispersion curves measured by inelastic neutron scattering, as input to the calculations. The calculations were based on cubic anharmonicity only. The results show a marked improvement in the wave number position of certain structure in the optical properties over that previously obtained using deformation-dipole lattice-dynamical data. The agreement with experiment at 300, 77, 20, and 12 K is generally very good apart from the obvious need for quartic anharmonicity at higher temperatures, a discrepancy in the wave number shift applied to the resonance wave number, and a few details of structure predicted by the shell model and not observed experimentally.
Infrared saturable absorbers. Part I: Five-level rate-equation analysis
Authors: Lim Tuan-Kay , Izatt Jerald R. , Caudle George F.
Published: April 2011

The saturation behavior of molecular absorbers characterized by absorption coefficients expressible as the ratio of two polynomials in the intensity is analyzed. Two cases are considered in detail. In the first, the absorption coefficient is the ratio of a linear equation in I to a quadratic equation in I. In the second, the highest order of the intensity occurring in both numerator and denominator is increased by two. The absorption coefficients are derived from two specific five-level models which are pertinent to the interpretation of the absorption of CO2 laser radiation at 937 cm−1 by SF6, but the analysis of the saturation curves is independent of the models from which they are derived. The saturation curves display as many as three extrema and provide considerable flexibility for fitting complicated experimental data. Both five-level models include excited-state absorption with the terminal level of the ground-state absorption distinct from the initial level of the excited-state absorption. Each of the five levels can be considered as a composite of many rotational states which interact in a like manner with the incident radiation. In one of the models the ratio of the excited-state and ground-state absorption cross sections is taken to be intensity dependent.
The reaction 7Li(e, 3H)4He,e′ between 6 and 15 MeV
Authors: Leung M. K. , Murphy II J. J. , Shin Y. M. , Skopik D. M.
Published: April 2011

Tritons resulting from the electrodisintegration of 7Li have been measured at 90° for an incident electron energy of 23.8 MeV over an energy range which ensured that only tritons emitted in the two-body channel were detected. The electrodisintegration cross sections were converted to equivalent photodisintegration data and compared to earlier results. Large discrepancies are observed. It is found that the (γ,3H) channel contributes appreciably to the electric dipole sum rule for 7Li.
The relationship between chemical composition and electrical conductivity of some North American micas
Authors: Crine J. P. , Friedmann A. , Wertheimer M. R. , Yelon A.
Published: April 2011

The electrical conductivity of various North American micas has been measured at room temperature for electric field strengths ranging from 102 to 5 × 104 V cm−1. It is shown that the conductivities observed are consistent with a percolation model in which Fe3+ provides the hopping centers.
Some recent developments in thermodynamics
Authors: Sobrino Luis de
Published: April 2011

An account of some recent developments in thermodynamics which do not appear to be widely known among physicists is given. While much of the original work is concerned with the mathematical theory, the physical ideas behind the formulation of the laws of thermodynamics for non-equilibrium systems are stressed here.
The 11B(α,γ0)15N reaction in the giant dipole resonance region
Authors: Bianco W. Del , Kundu S. , Kim J.
Published: April 2011

The 90° differential cross section of the 11B(α,γ0)15N reaction has been measured at α-particle energies from 5.74 to 17.80 MeV. The γ rays have been detected by a 23 cm long × 23 cm diameter NaI(Tl) crystal spectrometer enclosed in a plastic scintillator anticoincidence shield. The yield curve shows three well separated resonances at Eexc = 16.29 ± 0.15, 18.88 ± 0.20, and 21.26 ± 0.20 MeV.
Uniaxial strain dependence of the Fermi surface of tungsten
Authors: Stanley D. J. , Perz J. M. , Lee M. J. G. , Griessen R.
Published: April 2011

The derivatives of five representative cross sectional areas of the Fermi surface of tungsten with respect to uniaxial stress and strain along the cube axes, are determined experimentally from simultaneous measurements of quantum oscillations in magnetostriction and torque, and also in sound velocity and torque. The results are resolved into two components, the dependence on volume-conserving tetragonal shear, and the dependence on isotropic dilation. The tetragonal shear dependence is found to be in generally good agreement with the results of KKR calculations based on a fit to the unstrained Fermi surface. The isotropic dilation dependence agrees well with hydrostatic pressure measurements; from these results, the volume derivatives of the scattering phase shifts are deduced. This work is the first step towards a point-by-point determination of the distortion of the Fermi surface of tungsten in a lattice subjected to an arbitrary homogeneous strain.
Conduction electron g-factor in tungsten from quantum oscillations in ultrasonic velocity
Authors: Perz J. M.
Published: April 2011

From an analysis of the field dependence and harmonic content of quantum oscillations in the velocity of transverse ultrasonic waves associated with the ellipsoidal hole pockets at N in tungsten, the spin-splitting factor g = 1.73 ± 0.07 has been determined for central orbits near that of minimum area, i.e. with magnetic field H along a cubic axis [100]. This is consistent with the observed disappearance of the second harmonic oscillations for field nearly midway between two cubic axes, which implies g = 1.82 ± 0.07 for the relevant orbit.
Angular distributions and cross sections of the photoneutron reaction in 9Be in the photon energy region 18–26 MeV
Authors: Buchnea A. , Johnson R. G. , McNeill K. G.
Published: April 2011

The 9Be(γ,n0)8Be and 9Be(γ,n1)8Be reactions were studied in the photon energy region 18 to 26 MeV. The integrated cross section of the (γ,n0) reaction was found to be less than 0.1 MeV mb in this energy region. The integrated cross section for the (γ,n1) reaction in the energy region is 2.4 ± 0.4 MeV mb, which is 10 to 15% of the total photoneutron cross section. The measured angular distributions for the (γ,n1) reaction are consistent with the population of 3/2+ and 5/2+ states of 9Be. These results are consistent with slightly re-interpreted predictions of Majling, Kukulin, and Smirnov.
Effect of reflected molecules on rotational temperature measurements with rocketborne electron beam fluorescence probes
Authors: Haasz A. A.
Published: April 2011

Theoretical predictions were obtained for the effect of reflected nitrogen molecules on rotational temperature measurements with rocketborne electron beam fluorescence probes in the free molecular flow regime. Calculations for a typical payload (Black Brant AEF-II-118 flown from Fort Churchill, Man., Canada) indicate that the effect of reflected molecules can be significant and should be considered in the derivation of the theoretical temperature calibration curves.
Excitation of the 21S and 23S states of helium atoms by electron and hydrogen atom impact
Authors: Felden Madeleine M. , Felden Marceau A.
Published: April 2011

Ochkur's approximation is used to analyse the excitation of 21S and 23S levels of helium atoms from the ground state by electron and hydrogen atom impact. Calculations are made with different atomic wave functions. To characterize the 11S and 21S states we use, on the one hand, the wave functions of Byron and Joachain, on the other hand, those of Hylleraas and Marriott and Seaton. For the 11S and 23S states, calculations are made firstly with the wave functions of Byron and Joachain and Morse, Young, and Haurwitz, secondly with those of Shull and Lödwin. Numerical values are tabulated and compared in each case. The discrepancies show the importance of the choice of atomic wave functions in the calculation of the excitation cross sections. Available experimental data and corresponding theoretical values obtained from other theories are plotted and compared with the present results.
Four-photon resonant ionization of mercury
Authors: Tai C. , Dalby F. W.
Published: April 2011

Strong photoionization spectra have been observed in atomic mercury following absorption of laser light. In the frequency range 25 500 to 27 800 cm−1 many resonances corresponding to coherent three-photon absorption followed by one-photon ionization are reported.
Frame-transformation approximation for low-energy e−–1Σ+systems using the non-iterative integral equation method
Authors: Weatherford Charles A. , Henry Ronald J. W.
Published: April 2011

A discussion of the frame-transformation approximation appropriate for prediction of rotational and vibrational excitation cross sections for low-energy e−–1Σ+ systems is described. Explicit quantum number parameterizations of the time-independent Hamiltonian for both the body frame and the laboratory frame are given. A dynamical frame-transformation technique is described within the computational framework of the non-iterative, integral equation solution to the close-coupling scattering equations.
Spectroscopy of 121Te and 124Te from the 120,123Te(d,p)121,124Te reactions
Authors: Lien J. R. , Nilsen C. Lunde , Nilsen R. , Vold P. B. , Graue A. , Løvhøiden G.
Published: April 2011

The energy levels of 121Te and 124Te have been studied in the 120Te(d,p)121Te and the 123Te(d,p)124Te reactions using a 12 MeV deuteron beam. The targets were prepared in an isotope separator. Angular distributions of the emerging protons were recorded with an Enge split-pole magnetic spectrograph. The extracted spectroscopic results were compared to data from decay studies and to (d,p) results in other Te isotopes. A particularly low spectroscopic strength was observed for the h11/2 orbital in 121Te.
L'équilibre Vlasov dans la machine KEMP II avec limites réalistes d'énergie et de moment des particules du plasma
Authors: Matte J.-P. , Lafrance G. , Gregory B. C.
Published: April 2011

Plasma equilibria have been calculated numerically for the electromagnetic trap, KEMP II, from the Vlasov and Poisson equations. A plausible form for the electron and deuterium ion velocity distribution functions has been assumed. Compared with the previous work of Brunel Lafrance, Burkhardt, and Gregory, the present work provides a more realistic treatment of the limits of integration in the expressions for the moments of the distribution functions in order to allow for energy and momentum values permitting the charged particles to escape the machine or encounter a material electrode. The parameters in the theory have been varied around reasonable estimates provided by experiments so that their influence on the equilibria could be studied. The densities predicted by our calculations are one to two orders of magnitude smaller than experimental estimates. We postulate that this difference is explained by the fact that our theory does not take into account electrons reflected by the classical mirror effect in the cusp regions of the KEMP II machine, thus preventing them from shielding the anode potential.
Collision induced microwave absorption in N2, CH4, and CF4 in the gaseous and liquid phases
Authors: Urbaniak J. L. , Dagg I. R. , Reesor G. E.
Published: April 2011

Measurements of collision induced microwave absorption at 2.3 cm−1 have been carried out on gaseous N2 in the temperature range from 124 to 156 K and on liquid N2 in the temperature range from 77 to 125 K. The low density gaseous measurements have been found to agree well with the previous microwave and infrared results and with existing theories. The dependence of the absorption on density has been obtained at 156 K up to a density of 400 amagat and the results compared with the absorption in the liquid at the same density. The absorption is found to be a function of temperature and density but does not depend on the molecules being in a gas or liquid phase. Results for liquid CH4 and CF4 are reported and compared with previous microwave gaseous results. In contrast to the results for N2 the dependence on the square of the density changes by a relatively small amount in going from the low density gas to liquid densities.
Integral rotation of the 5/2− 193-keV level of 63Zn
Authors: Nir D. , Cameron J. A.
Published: April 2011

Integral rotation of the angular distribution of gamma rays following the 60Ni(α,n)63Zn reaction in a magnetized 60Ni10Fe90 target yields for the 5/2− 193-keV level a product gτ = (2.7 ± 0.8) × 10−10 s. Using a g factor of 0.30, consistent with those of 5/2− levels in other Zn isotopes, one obtains, as an estimate of the lifetime, τ = (9 ± 3) × 10−10 s.
The role of short range interaction in molecular collision broadening
Authors: Srivastava R. P. , Zaidi H. R.
Published: April 2011

The effect of a short range interaction on collision broadening is investigated for molecular transitions. Expressions for the collision width are derived for an intermolecular potential consisting of a multipole term together with a core potential of the form r−n. Impact and straight classical path approximations are used. The short range interaction is included to all orders, but contributions up to second order are retained for the multipole interaction. This approach eliminates the need for a cutoff at small impact parameters. Our results represent the proper generalizations, which reduce to the results of the Anderson theory, in the limit as n → ∞. This work suggests that some information about the effective core potential can be obtained from a comparison of the theory and the experiment.
Self-broadened widths of rotational Raman and infrared lines in CO2
Authors: Srivastava R. P. , Zaidi H. R.
Published: April 2011

Self-broadened widths for the rotational Raman and infrared lines in CO2 are calculated using the approach of the preceding papers. Comparison is made with the experimental data, and with the results of the existing theories. Core potential parameters are determined from the comparison of theory and experiment. It is found that the same value of the average quadrupole moment can explain the Raman as well as the infrared data. (Different values were used in the existing calculations.)
Librational motion in the α phase of solid nitrogen. I. Basic theory and results
Authors: Dunmore Paul V.
Published: April 2011

Librational motion in the α phase of solid nitrogen is studied on the basis of a model that ignores the translational motion of the molecular centres of mass. A general expansion in spherical harmonics is written down for an arbitrary two-body intermolecular potential, and methods are presented for obtaining the expansion coefficients for a particular potential model. The crystal Hamiltonian is written down and the mean-field approximation is briefly discussed. The eigenstates of the mean-field Hamiltonian are shown to correspond formally to the eigenstatesof the two-dimensional isotropic harmonic oscillator, and this correspondence is exploited to define boson creation and annihilation operators for excitations of a single molecule. The full crystal Hamiltonian is expressed in terms of these operators and the bilinear terms are diagonalized by an RPA treatment which is an extension of one given by Raich and Etters. Numerical results for the libron frequencies at the Γ and R points in the Brillouin zone are presented for the potential models proposed by Kohin and by Raich and Mills, the calculations having been performed with the intermolecular potential including terms as far as l = 6. The temperature dependence of the nuclear quadrupole resonance (NQR) frequency calculated with the Raich–Mills potential is shown to be in very good agreement with the measurements of Brookeman, McEnnan, and Scott. Finally the orientational probability density is presented as a function of temperature.
Librational motion in the α phase of solid nitrogen. II. Neutron scattering
Authors: Goodings D. A.
Published: April 2011

An expression is derived for the one-libron coherent inelastic structure factor for neutron scattering by libron modes in the cubic α phase of solid nitrogen. The results of calculations show that for certain modes at the Γ and R points in the first Brillouin zone and for the scattering vector Q along certain directions in reciprocal space the structure factor vanishes. The results are in excellent agreement with the recent inelastic neutron scattering measurements of Kjems and Dolling.
Opening angles of electron–positron pairs
Authors: Richards L. E. , Kim C. Y.
Published: April 2011

G-5, 200 μm, nuclear emulsion plates were exposed to a bremsstrahlung photon spectrum of known intensity, produced by 100 MeV electrons at the Saskatchewan Linear Accelerator. The emulsions were later scanned for electron–positron pairs. Measurements were made such that the pair opening angle could be determined. From the resulting distribution of angles, the photon spectra predicted by the theories of Borsellino and Olsen, relating the most probable photon energy to a measured opening angle, were calculated. These spectra were compared to the experimental photon spectrum for the energy interval 50 to 100 MeV. Agreement was obtained for the theory of Olsen, within experimental error.
Spectral albedo corrections to ISIS 2 satellite auroral photometer data
Authors: Harrison A. W. , Anger C. D.
Published: April 2011

The unique situation afforded by the cartwheel scanning mode of the ISIS 2 satellite 3914 Å photometer over quiet auroras provides the basis for an assessment of earth surface albedo contributions to the observed auroral brightness as seen from above the aurora. A detailed analysis of specific satellite passes shows the validity of the procedure described by Hays and Anger for removal of the albedo contribution and restoration of the true auroral brightness profile. Reliable estimates of the integrated photon flux coming from a thin cross-sectional 'slice' through the aurora can be made even when the aurora is very near or even superimposed upon the earth's limb.
SU(1,4) as a dynamical group; analysis of all the discrete representations. I. Baryons
Authors: Kalman C. S.
Published: April 2011

A method using SU(1,3) as a dynamical group for the baryons is extended to SU(1,4) by inclusion of the charm symmetry group SU(4) as maximum kinematic group. Several new mass formulae are given and the masses of the charmed baryons are predicted.
SU(6)w fits in baryon photo- and electroproduction: D13(1520), an example
Authors: Avilez C. , Eisenschitz T. S.
Published: April 2011

Assuming that the electromagnetic current transforms under SU(6)w as a 35-plet, we check the accuracy of determining transition matrix elements within one SU(6)w multiplet from a few amplitudes which must be fitted, connected by Clebsch–Gordan factors.We find the symmetry to be so badly broken that the procedure is unjustified, and that the common belief that an improvement in the accuracy of the data will improve the accuracy of the fit is false.
A study of high spin states in 151Gd
Authors: Smith H. J. , Johns M. W. , Løvhøiden G. , Thompson J. V. , Waddington J. C. , Volkov A. B.
Published: April 2011

States in the transitional nucleus, 151Gd, excited by the (α,2n) reaction have been studied by gamma-ray and conversion electron measurements. Gamma-ray energies, intensities, excitation functions, and γ–γ coincidence measurements were used to establish the levels populated. Angular distributions involving measurements at seven angles from 0° to 90° and K-conversion coefficients have been used to make spin and parity assignments.The El character of the 65, 79, 340, 358, 406, and 462 keV transitions, which in the absence of K-conversion data had been tacitly assumed to be M1 by earlier workers leads to a significant revision of their parity assignments and interpretation of the level structure. The negative parity states at 1210, 1463, 1726, 2004, 2295, 2600, 2915, and 3237 keV form a well-developed rotational band based on the 11/2− [505] state at 1210 keV. The properties of this band in this nucleus are compared with those of the same band in a number of nearby nuclei. Two non-interacting negative parity bands with states at 0(7/2−), 706(11/2−), 1435(15/2−), 2078(19/2−), and 379(9/2−), 902(13/2−), 1511(17/2−), 2297(21/2−), respectively, have been found, as well as a number of other negative parity states of spin 7/2, 9/2, and 13/2. A complex positive band structure involving states at 784(11/2+), 852(13/2+), 1116(13/2+), 1346(17/2+), 1364(15/2+), 1677(17/2+), 1851(19/2+), 1853(21/2+), 2197(21/2+), 2325(23/2+), and 2405(25/2+) has been identified. By using a somewhat unusual set of parameters, we have been able to approach a description for the positive parity states in terms of the triaxial model of Meyer-ter-Vehn.
Pt–Cu2O–Cu double injection diodes
Authors: Chee K. T. , Weichman F. L.
Published: April 2011

We report here on recent measurements made on our Pt–Cu2O–Cu diodes, annealed at an air pressure of 1 to 2 Torr, which we interpret as due to double injection, i.e. injection of holes from the platinum electrode and injection of electrons from the copper–Cu2O junction into the single crystal Cu2O region. The measurements discussed here include the forward I–V characteristics at various temperatures, current vs. thickness relationship at constant voltage, the effect of photo-memory on the I–V characteristics, and the discovery of a negative resistance regime at below room temperature at sufficiently high injection levels. The analysis of the temperature dependence of the current in the ohmic and the [Formula: see text] regimes, together with the effect of photomemory on the I–V characteristics enable us to identify the [Formula: see text] regime as the Ashley–Milnes regime with field dependent mobility.
Pt–Cu2O–Cu single-carrier space-charge-limited diodes
Authors: Weichman F. L. , Chee K. T.
Published: April 2011

This paper reports on the experimental results on the characteristics of the single-crystal Cu2O diodes, annealed at a pressure of 10−6 Torr at a temperature of 800 °C. In contrast to our previous report on oxidized samples which showed the characteristics of double injection diodes, these diodes exhibit the characteristics of single-carrier space-charge-limited (SCL) conduction. The conduction mechanism was confirmed by measurements on the I–V characteristics at various temperatures, the thickness vs. current relation at a given voltage, the effect of photomemory on the I–V characteristics, and the transient current response to applied voltage steps. The results also indicate that there are continuous levels of localized states in these samples in the range 0.06 eV to 0.47 eV above the valence band edge.
Computer calculations of slow electrons scattering by sodium atoms
Authors: Bui T. D.
Published: April 2011

This is an addendum to a previous paper (Bui and Stauffer, to be referred to as I). The explicit formulae which are not given in I for the case of electron–sodium atom scattering are given in this addendum. Tables of all appreciable partial waves with L ≤ 10 are presented for various values of the energy of the incident electron up to 4 eV. Results for the total elastic cross sections are compared with the most recent variational calculations of Sinfailam and Nesbet.
Residual resistivity of Al in Zn
Authors: Tomlinson P. G. , Carbotte J. P.
Published: April 2011

We report results of numerical calculations of the residual resistivity due to an Al impurity in Zn which include, for the first time, the multiple plane wave electronic band structure of Zn. The topology of the Fermi surface, the Fermi velocities, and the plane wave mixing coefficients are taken from the model pseudopotential of pure Zn developed by Tomlinson and Swihart. To solve the Boltzmann equation, a variational principle is employed with up to six trial functions. For comparison, a scattering time solution is also obtained. Both solutions give very similar results which are found to be not too different from the present experimental value.
Multiple plane wave calculation of the resistivity of Pb and dilute Pb alloys
Authors: Tomlinson P. G. , Carbotte J. P.
Published: April 2011

We compare with each other and with experiment results for the ideal resistivity of Pb based on several approximate solutions of the Boltzmann transport equation. The Fermi surface geometry, Fermi velocities, and electronic wave functions in the four plane wave model are calculated from the pseudopotential of Anderson and Gold obtained from de Haas – van Alphen data. The lattice dynamics is taken from the Born–von Karman force constant model of Cowley obtained from neutron scattering data on the dispersion curves. In the electron–phonon matrix element, we use the pseudopotential form factor of Appapillai and Williams. The calculations are extended to the case of Mg in Pb and deviations from Matthiessen's rule obtained.
Microwave absorption and dielectric relaxation of some rigid molecules and their mixtures
Authors: Madan M. P. , Shelfoon M. , Cameron I.
Published: April 2011

The dielectric constant and loss factor of some rigid molecules, pyridine, quinoline, and isoquinoline, and their mixtures have been measured in dilute benzene solutions in the microwave region over a range of temperatures. The dielectric data have been used to determine the relaxation times and the thermodynamic parameters for the activated state. The values of the relaxation time for single polar component solutions agree well at temperatures at which there are available known data. The relaxation times for the mixtures are consistent with the results on simple liquid mixtures of polar molecules in dilute solutions which were previously studied by us and by some other workers.
Partly non-local potentials in the model triton
Authors: Ellis Dale D.
Published: April 2011

Binding energy, ET, wave function, form factor, and asymptotic normalization constant, CT, have been calculated for the model triton using two classes of phase equivalent potentials: partly non-local (PNL) potentials, and rank-two separable potentials. The results are compared with those of Fiedeldey. The binding energy is sensitive to the deuteron wave function and zero-energy wound integral. The triton form factors depend on ET and the deuteron wave function. CT is almost insensitive to variations in the PNL potentials, but increases with ET for the separable potentials.
Microscopie interférentielle par double shearing et application à l'étude non destructive de l'homogénéité des fibres optiques
Authors: Verly P. G. , Lit John W. Y.
Published: April 2011

An extremely simple setup is used to compare different images formed by double-shearing interference. The methods are applied to detect inhomogeneities in optical fibres. A theoretical analysis of a few interference images and some experimental results are presented. [Journal translation]
A weak-coupling model for the even Zn isotopes
Authors: Vo-Van T. , Wong S. S. M.
Published: April 2011

The low-lying structures of even zinc isotopes are studied as the weak coupling of vibrational states of protons and neutrons obtained from shell-model calculations. In spite of its simplicity, the model is capable of describing the known level structure and E2 transition rates as well as producing reliable two-proton transfer amplitudes. Extensions to include other even–even nuclei such as Ge, Se, and Kr are also discussed.
Photo-disintegration of the deuteron with soft-core potentials
Authors: Abidi S. T. H. , Srivastava B. K.
Published: April 2011

We calculate the photo-disintegration integrated (σint) and bremsstrahlung-weighted (σb) cross sections of the deuteron by applying the sum rules of Levinger and Bethe. In our calculations we use the soft-core potentials of Reid and of Eikemeir and Hackenbroich. Our results for σint and σb agree well with experiments.A common feature of the σint calculations of the deuteron with different realistic potentials is their inability to distinguish between any two realistic potentials. We explain this feature in terms of the range-depth relationship for the potentials. Based on this explanation, we propose a simple model for the calculation of σint of the deuteron which uses the radial S- and D-wave functions for a given potential and the mean values of the central and tensor components of the potential energy operator.
La résistivité électrique et la constante diélectrique à fréquence infinie duCd3As2 à 77 et 300 K
Authors: Jay-Gerin J.-P. , Caron L. G. , Aubin M. J.
Published: April 2011

The electrical resistivity of Cd3As2 at 77 and 300 K has been calculated as a function of electron concentration. The contribution of ionized impurities, acoustic and optic phonons to the electronic scattering was evaluated taking into account the HgTe-type inverted band structure of this material. A fit of these results to the experimental ones appearing in the literature yields a high-frequency dielectric constant εx of 12.
Semiclassical theory of superfluorescence
Authors: Zardecki Andrzej , Baribeau Réjean
Published: April 2011

The fluctuating properties of superradiant and superfluorescent systems are investigated by supplementing the equations of motion for the expectation values of quantum observables with random force terms. In the case of a small atomic system the time evolution of the radiated intensity as well as the intensity fluctuations are computed. We also find the time dependence of the average dipole moment in the presence of chirping. For a pencil-shaped geometry, a generalized system of Maxwell–Bloch equations is analysed. The inhomogeneous broadening is then included. We compare the semiclassical equation for the probability distribution of the atomic variables with the quantum equations based both on normal and antinormal ordering. With the exception of the region in the vicinity of the poles of the Bloch sphere, a close correspondence between the semiclassical and quantum theories is established. The oscillatory superfluorescence is treated similarly to quantum analysis by employing a new method of Lugiato for open systems.
Density of metastable atoms in an argon plasma produced by an RF surface wave
Authors: Moisan M. , Ricard A.
Published: April 2011

The maximum density of argon atoms in excited metastable states, in a plasma produced by surface wave propagation, is studied experimentally. Measurements are performed by the absorption method, perpendicularly to the tube axis. The measurements show that the maximum population densities of the 3p54s metastable levels in argon are larger in the RF plasma than in the positive column of a glow discharge, between 0.02 and 0.4 Torr in a 26 mm i.d. tube. This fact could be used to improve gas laser operation.
Effet thermomagnétiques dans le plomb pur
Authors: Delon P.
Published: April 2011

We have shown an entropy transport effect, similar to the Ettinghausen one observed in the type II supraconductors, but with opposite sign. It is characterized by the shifting of magnetic vortices in the laminar structure characteristic of the intermediate state of type I supraconductors. This explanation seems to be confirmed by experimental results.
Differential cross sections and angular correlation parameters for the excitation of the n = 3 levels of helium by electron impact
Authors: Winters K. H. , Issa M. , Bransden B. H.
Published: April 2011

Angular distributions and (x, λ) angular correlation parameters are calculated in the generalized distorted wave model of Bransden and Issa for 31P excitation of helium in the energy interval 100 to 500 eV. Comparison is made with the experimental data at 100 eV and with the results of the theoretical models. Angular distributions are also presented for the excitation of the 31S and 31D levels, for which a comparison with data is not yet possible.
On the saddle point evaluation of LF/VLF path integrals for a vertical electric dipole
Authors: Gonzalez Guillermo , Berry Leslie A.
Published: April 2011

The various factors in the saddle point approximation to the path integrals of wave hop theory are identified with their geometrical optical equivalents more completely than heretofore. In the process, one 'diffractive correction' to the convergence coefficient of geometrical optics is shown to be invalid in the shadow region. The range of validity of the approximations is quantified, and the saddle point approximation and classical geometrical optics results are compared numerically. Height-gain functions are introduced in the equation for the path integrals. Finally, the saddle point approximation for the general case of an elevated transmitter and (or) receiver is derived. In this case, there are four saddle points corresponding to the four possible wave paths.
Asymptotic field of evanescent waves of a Hertzian dipole
Authors: Schmidt-Weinmar H. G.
Published: April 2011

The asymptotic expansion of the electromagnetic field associated with plane waves of the evanescent type in the transverse magnetic (TM) field of an electric point-source dipole has been obtained for large axial and off-axial distances of a half-space. (1) The point-source-dipole field bandlimited to the exclusion of all evanescent waves does not satisfy strong radiation conditions of order r−2 at almost all field points in every direction as the radial distance [Formula: see text]. (2) The point-source-dipole field that contains the uniform-plane-wave components plus a bandlimited low-frequency part of the evanescent-wave spectrum satisfies approximately strong radiation conditions of order r−2 as [Formula: see text] for fixed (x2 + y2)1/2. (3) The point-source-dipole field has to be unbandlimited so as to include all evanescent-wave components in order to satisfy strong radiation conditions of order r−2 as [Formula: see text] for any fixed value of z.
Interactions between ortho-H2 molecules in nearly pure para-H2
Authors: Harris A. B. , Berlinsky A. J. , Hardy W. N.
Published: April 2011

A comprehensive theory is presented for the interaction of two ortho-H2 molecules in otherwise pure solid para-H2. A general Hamiltonian is constructed, which takes full account of the local environment of the pair of ortho molecules. For the dominant interactions between the pair, the pair axis is an axis of cylindrical symmetry. The various parameters which describe these interactions are then calculated from a microscopic theory. Contributions to these parameters include the 'bare' interaction parameters of the pair, ε00, ε20, and ε40, where ε40 is mainly determined by the quadrupole coupling constant Γ0. In addition, there are renormalizations due to various solid state effects, e.g. zero point motion, three-body polarizations, etc. These cylindrically symmetric interactions split the nine energy levels of the pair into three singlets and three doublets. The doublets are split by smaller interactions which sense the lack of cylindrical symmetry in the local crystalline environment. Among these are (1) the crystalline field whose axis of symmetry, the crystal c-axis, does not coincide with the pair axis, (2) three-body electronic polarizability interactions of order Γ0ρ, where ρ is proportional to the molecular polarizability, (3) three-body 'rotational polarizability' interactions of order Γ02/B, where B is the rotational constant, (4) higher order polarizability interactions, and (5) phonon- and zero point-induced interactions which depend on the anisotropy of motion transverse to the pair axis. The effect of zero point motion and short-range correlations on the three-body polarizability interactions has also been computed. Wave functions and energy levels for the pair are derived from this Hamiltonian, and the coefficients for infrared absorption by the quadrupole – induced dipole mechanism are calculated.
Resonance broadening in high density gases
Authors: Zaidi H.R.
Published: April 2011

The resonance broadening of a transition between two excited states of a radiator in a high density gas is investigated. The important many body shielding contributions are included to all orders, and the two body correlations for the close collisions are approximately taken into account. Corrections to the line width and shift at moderately high densities are calculated. The results agree with the experimental data for krypton. The density dependence of the width parameter is examined at very high densities also. It is found that this parameter, after reaching a peak value, decreases with further increase in the density. Moreover, the square root dependence of the line widths on the density is not valid over any extended range of gas densities.
Quantification du champ électromagnétique au voisinage d'un miroir plan métallique
Authors: Grossel Philippe , Vigoureux Jean-Marie , Payen Raymond
Published: April 2011

We quantify the electromagnetic field in a half-space bounded by a perfect mirror. By analogy with the quantization near a dielectric, by Carniglia and Mandel, we use doublet modes obtained by superposition of incident and reflected waves satisfying Fresnel's conditions. These functions form a complete basis in the space of the field states. By expanding the electromagnetic field in terms of these doublet modes, the energy and the impulsion parallel to the mirror reduce to the sum of the contributions of independent harmonic oscillators. It is therefore possible to quantify as in a free field. We use successively Maxwell–Minkowski's tensor and de Broglie's. With the latter, the calculus is more straightforward and easier than with the former. The interest in quantum formalism of doublet modes is that interactions with the electromagnetic field near a mirror can be studied as in a free field.
Search for tachyons preceding cosmic ray extensive air showers of energy
Authors: Smith Gary R. , Standil S.
Published: April 2011

A search for tachyons preceding extensive air showers has been conducted using an air shower array operated in conjunction with a large aperture, five element cosmic ray telescope. More than 200 000 air showers of primary energy [Formula: see text] were observed over a period of 223 days and a 290 μs period before each of these showers was scanned for a related particle signal from the telescope. In this way a particle arrival time spectrum containing 1519 tachyon candidates was observed. No convincing evidence was found for any subgroup of these events that might be attributable to tachyons.
Optical properties of Cu− centres in NaCl crystals
Authors: Tsuboi Taiju
Published: April 2011

For a systematic study of the isoelectronic series of s2-type centres, absorption, excitation and emission spectra of Cu− centres in NaCl crystals are investigated in the ultraviolet and vacuum ultraviolet spectral range at temperatures from 77 to 300 K. Two weak absorption bands were observed at 269 and 256 nm in addition to four bands at 288, 272, 232, and 189 nm which are assigned to the A, B, C and D bands of s2-type spectra, respectively, while only two emission bands peaking at 423 and 318 nm were detected. These results of Cu− centres are compared with those of the hitherto investigated s2-type centres.
Conservation laws and gravitational radiation
Authors: Rastall Peter
Published: April 2011

A total stress-momentum is defined for gravitational fields and their sources. The Lagrangian density is slightly different from that in the previous version of the theory, and the field equations are considerably simplified. The post-Newtonian approximation of the theory is unchanged. The existence and nature of weak gravitational waves are discussed.
Nuclear spin relaxation and centrifugal distortion effects in dilute silane gas
Authors: Beckmann Peter , Burnell E. Elliott
Published: April 2011

We have measured the proton longitudinal spin relaxation rate in dilute gaseous silane (SiH4) between 10−2 and 1 amagats and are able to observe the influence of rotational Q branch centrifugal distortion transitions.
The mode transition process in collisional drift waves and self-consistent plasma diffusion across a magnetic field
Authors: Jones R.
Published: April 2011

Drift wave induced cross field plasma transport is observed to destabilize new drift instabilities which then act to quench the original linear mode and enhance diffusion.
An automatic scanning integrating spectronephelometer
Authors: Harrison A. W.
Published: April 2011

A nephelometer has been constructed at the University of Calgary, Calgary, Alberta for obtaining visible and near infrared spectra of aerosol and Rayleigh gas scattering by combining the instrument with a Czerny–Turner automatic scanning spectrometer. The spectronephelometer, as it is called, has been shown to produce ambient aerosol spectra which can be used in several related investigations. Calibration of the instrument is discussed in some detail as it relates to use of the instrument in observational work.
Integral equation approach to the problem of scattering by a number of fixed scatterers
Authors: Hron M. , Razavy M.
Published: April 2011

In the derivation of the Lippmann–Schwinger integral equation for scattering of a wave ψ(r) by the potential ν(r), one constructs the Green's function for the operator [Formula: see text], and treats νψ as the inhomogeneous term. However, in certain cases, it is desirable to formulate the scattering problem in terms of an integral equation by obtaining the Green's function for the operator [Formula: see text], and by considering (−k2ψ) as the inhomogeneous term. An important aspect of this formulation is that the resulting integral equation can be used to generate a low energy expansion of the wave function for some separable and nonseparable systems. For two-dimensional scattering, if the geometry of the scatterers is simple enough, the Laplace equation with the prescribed boundary conditions on the surface of the scatterers is separable in a certain coordinate system, then one can write the solution of the wave equation as an inhomogeneous integral equation. In this way the problems of scattering by two cylinders, an array of cylinders, and a grating can be formulated in terms of integral equations. For three-dimensional scattering, one can consider either the spherically symmetric cases or nonseparable problems. In the former case, for certain types of force laws, a Volterra integral equation in one variable can be found for the wave function. In the latter case, integral equations in two or three variables can be obtained for scattering by two spheres or by a torus.
Details of the structure of bound excitons and bound multiexciton complexes in Si
Authors: Thewalt M. L. W.
Published: April 2011

The high resolution photoluminescence spectra reported here reveal new details of the structure of both bound excitons and bound multiexciton complexes in donor and acceptor doped Si. The bound exciton and bound multiexciton complexes in Si containing P impurities are found to have excited states, as was postulated in a recent shell-model of the bound multiexciton complexes. Several new features of the luminescence due to bound excitons and bound multiexciton complexes in acceptor doped Si are also found to be in agreement with the shell-model. In contrast to previous studies, we find no reason to doubt the original bound multiexciton complex explanation of the luminescence line series which are seen in lightly doped Si. The implications of these results are also discussed in relation to previously reported interpretations of the photoluminescence spectra of donor-doped Ge.
Magnetic properties of (NixCu1−x)2MnSn
Authors: MacDonald R. A. , Stager C. V.
Published: April 2011

Magnetization and crystallographic measurements are reported for the Heusler alloy series (NixCu1−x)2MnSn. With the exception of Cu2MnSn and perhaps (Ni0.1Cu0.9)2MnSn all of the samples prepared had the cubic Heusler L21 structure at room temperature. The lattice parameter varies linearly as a function of composition. The saturation moment is constant at approximately 4μβ per manganese atom throughout the series. Curie temperatures vary smoothly but non-linearly with composition, providing some evidence for at least two competing mechanisms in the determination of the Curie temperature.
Etude spectrométrique de la perturbation du niveau vibrationnel ν = 1 de l'état B2Σu+ de N2+ dans les bandes (1,0), (1,1), (1,2) du système B2Σu+–X2Σg+
Authors: Bouchoux A. M. , Goure J. P.
Published: April 2011

The (1,0), (1,1), (1,2) bands of the system B2Σu+ – X2Σg+ of the ion N2+ are obtained in a hollow cathode discharge. The high resolution spectrometric recording has permitted an analysis of the frequencies and of the relative intensities of the rotational lines. The molecular constants and the parameters ξ and η of the perturbation of the vibrational level ν = 1 of the B2Σu+ state by the level ν = 11 of the state A2Πu have been determined.
The preparation and some electronic properties of a-ZnSe
Authors: Lim P. K. , Brodie D. E.
Published: April 2011

This paper describes the preparation of mature amorphous ZnSe, obtained in thin film form by vapor deposition of the ZnSe compound. Room temperature resistivities of annealed a-ZnSe samples are ~1013 Ω cm. The material is n-type and the dc conductivity is consistent with a hopping conduction mechanism at temperatures up to the rapid crystallization temperatures which occur around 180 °C and higher. The activation energy for hopping at the band edge is 0.9 ± 0.05 eV and it is 0.09 ± 0.02 eV for hopping at the Fermi level, Ef.Variable range hopping occurs at Ef, below 270 K, and the density of states N(Ef) at Ef is of the order of 1017 (cm3 eV)−1. Annealing a-ZnSe prior to obtaining fully matured samples reduces N(Ef).