bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical stability and strength of a single Au crystal
Authors: Zhang J -M , Yang Y , Xu K -W , Ji V
Published: October 2017

The structural stability and theoretical strength of a Au face-centered cubic (FCC) crystal under uniaxial loading is investigated by combining the modified analytical embedded atom method (MAEAM) with Born stability criteria. The results show that under sufficient compression, there exists a stress-free body-centered cubic (BCC) phase, which is unstable and slips spontaneously to a stress-free metastable body-centered tetragonal phase by consuming internal energy. The structural energy difference between the BCC and FCC phases is in good agreement with the experimental value. The stable region ranged from –2.21 GPa to 6.31 GPa in the theoretical strength or from –9.83% to 7.87% in the strain correspondingly.PACS Nos.: 62.20.–x, 61.50.Ks, 81.05.Bx
Empirical and semiempirical models of the formative time delay in nitrogen
Authors: Marković V Lj , Stamenković S N , Gocić S R
Published: October 2017

The formative time dependence on working voltages tf(U) in nitrogen is determined: (1) from the Laue diagrams, by taking the values where the linear approximation of the electrical breakdown time delay (td) intersects the time axis, (2) from histograms, by taking the minimum values of the delay times for the formative time, and (3) from a difference tf = [Formula: see text] – [Formula: see text] ≈ [Formula: see text] – σ (td), where standard deviation σ,(td) is approximately equal to the mean of the statistical time delay [Formula: see text]. The breakdown time delay measurements are supported by oscilloscopic measurements of the voltage drop and the current rise time during inception of the discharge. Several simple models were applied to describe the experimental formative time dependence on working voltages tf,(U) and a good agreement with experimental data was found.PACS Nos.: 51.50.+v, 52.80.–s
Diffraction by a Laser Induced Thermal Phase Grating. I
Authors: Enns R. H. , Rangnekar S. S.
Published: October 2017

The problem of diffraction by a laser induced thermal phase grating is solved in a self-consistent manner. Solutions, valid over a wide range of experimentally attainable conditions, are given and a sum rule is derived to test the validity of the solutions. These solutions are compared with those obtained by other workers and the experiments of Eichler et al. and Eichler and Kluzowski are examined in the light of our new solutions.
Spectre d'émission de la molécule PO : transitions D2Π–B2Σ+ et D′2Π–B2Σ+ des molécules P16O et P18O. Reconsidération de l'état de valence D′2Π
Authors: Coquart B. , Paz M. Da , Prudhomme J. C.
Published: October 2017

New vibrational levels of the D′2Π state for P16O and P18O interacting with the level ν = 0 of the D2Π state are studied by means of a transition to the B2Σ+ state. Deperturbation calculations have been carried out. The results obtained lead us to look at two hypotheses. In particular, the eventuality is considered that D′2Π and B′2Π are the same state, some high levels of which are observed here.
Sum Rule Photodisintegration Cross Sections of 6Li
Authors: Yadav H. L. , Srivastava B. K.
Published: October 2017

We apply the sum rules of Levinger and Bethe to calculate the integrated

[Formula: see text]

cross sections for 6Li using the Gaussian and Irving forms of radial wave functions whose parameters are determined by fitting the r.m.s. radius of charge distribution in 6Li. For the potential in the σint calculation we use the central velocity-dependent potential of Herndon et al. Our results for σint and σb for 6Li show reasonably good agreement with experiments.
Recent Developments in Sonic-Boom Simulation Using Shock Tubes
Authors: Gottlieb J. J. , Glass I. I.
Published: October 2017

Gasdynamic and acoustic analyses were performed in order to provide greater insight into the operation of sonic-boom simulators utilizing shock-tube drivers. Three basic shock tubes were considered; each had a pyramidal driver joined at the diaphragm station to a pyramidal channel of the same divergence angle (pyramidal shock tube), or of a different angle, or joined to a constant-area channel. Classical acoustic theory was applied to obtain new analytical solutions to describe the wave motion in such facilities, in agreement with experimental data. In addition, a detailed study of the nonlinear generation and propagation features of the N wave was made for the important and practical case of the pyramidal shock tube. The work described above is of current interest as shock-tube-type facilities are in present use in France, Germany, England, the United States, and Canada to assess societal problems associated with sonic boom.
Lensing Effect in Helical TEA Lasers
Authors: Otis G. , Tremblay R.
Published: October 2017

A complete analysis of the lensing effect in helical TEA lasers is presented. Based on the theory of the gas lens, a theoretical model is developed and found capable of explaining the fast and slow time behavior of the lensing effect. It is also found that at the instant of laser emission, the helical TEA laser still presents a parabolic index of refraction profile.
Elastic Scattering of Positrons in Neon and Argon and Phase Shift Analysis from 4 eV to Inelastic Thresholds
Authors: Jaduszliwer B. , Paul D. A. L.
Published: October 2017

The transmission of positrons through neon gas has been studied in the elastic region below the positronium formation threshold at energies from 4 eV to 14 eV, and the same experiment was carried out for argon from 4 eV to 8 eV. By repeating the measurements using three values of magnetic field along the scattering chamber, in the direction of transmission, some sensitivity to individual phase shifts is obtained, and a phase shift analysis has been carried out. The l = 0, 1, and 2 shifts are each parametrized as a two term power expansion in the wave number, while the forms of δ3, δ4 are assumed from theory. The results of the analysis are compared with published theories and indicate the need for more accurate calculations, particularly for argon. The total cross sections deduced for neon are in disagreement with the smaller values measured by Canter, Coleman, Griffith, and Heyland, but the cross sections for argon are in agreement with theirs.
Radio-Frequency Probes in a Nonlinear Isotropic Plasma
Authors: Bantin Colin C. , Balmain Keith G.
Published: October 2017

Nonlinear cold-plasma and scalar-pressure theories are derived and applied to a spherical RF probe in a plasma. With two specified RF potentials on the probe at different frequencies, calculations are presented for the second-order probe output responses. These include the second harmonic, the sum and difference frequencies, and the d.c. increment (resonance rectification). The nonlinear response as a function of frequency is shown to depend strongly on whether the input signals are maintained at a constant current or a constant voltage; for diagnostics, the constant-current technique permits identification of the plasma frequency, whereas the constant-voltage technique does not.
Monopole and Dipole Antennas in a Nonlinear Isotropic Plasma
Authors: Bantin Colin C. , Balmain Keith G.
Published: October 2017

The theoretical nonlinear response of a plasma is studied for the case of two RF signals simultaneously applied to the terminals of thin-wire monopole and dipole antennas of arbitrary length. Distributed nonlinear sources of charge density and current density are identified and used to calculate induced open-circuit antenna terminal voltages at harmonic, sum, difference, and intermodulation frequencies and at d.c. (rectification). The importance of the antenna as a field scatterer is identified for the calculation of radiation fields and higher-order near fields. Experiments on the terminal properties of a monopole antenna were performed in a laboratory gas discharge and quantitative agreement with cold-plasma theory is demonstrated for frequencies above about half the plasma frequency; lower frequency response closely resembles earlier predictions using warm-plasma theory. Experiments and theory for a constant RF input current indicate that the plasma frequency can be identified and therefore that the antenna system is useful for electron-density diagnostics. Experiments indicate a complex form of signal limiting or saturation, but below this level there exist situations where the nonlinear response is high enough to be classified as interference in practical systems.
Evaluation of Nuclear Matrix Elements Involving Harmonic Oscillator Wave Functions
Authors: Scott C. K. , Singh R. N.
Published: October 2017

A simplified form of the integral of products of harmonic oscillator wave functions is presented, with application to the evaluation of common nuclear matrix elements.
Theoretical Calculations of Relative Intensities in Hyperfine Diatomic Transitions
Authors: Féménias J. L. , Athénour C. , Stringat R.
Published: October 2017

A method of calculating molecular wave functions in complex 'hyperfine' coupling cases is presented. It enables us to express (bβJ) and (bβS) wave functions in terms of more simple (aβ) functions, and to connect their parities and symmetry characters to those of 'classical' (b) wave functions. With the help of these expansions of (bβJ) and (bβS) wave functions, we have carried out the calculation of the reduced matrix elements of electric dipole moment M in order to study the intensity distribution in optical transitions between excited diatomic electronic states belonging to the (aβ), (intermediate aβ–bβJ), and (bβJ) coupling case, and a ground state belonging to the (bβS) coupling case. First comparisons with experimental results in the ScO molecule are made, and these enable us to give theoretical confirmation to some previous assumptions.
Electron Emission from Metals Excited with a CW CO2 Laser
Authors: Duley W. W.
Published: October 2017

The time dependence of electron and ion emission from roughened metals on excitation with a CW CO2 laser has been studied. The emission currents are made up of pulses with durations of several ms. A complex dependence of both ion and electron current on time is observed on time scales ranging from ms to days. An interpretation of these effects based on thermionic emission from localized surface sites is given, and the possible role of exoelectron emission is discussed. Some possible applications of these effects are examined.
The Normal Modes of Linearized Magnetohydrodynamics
Authors: Corkum P. B.
Published: October 2017

The central purpose of this paper is to derive a general set of magnetohydrodynamic equations for a two component plasma in an external magnetic field and to find the eigenmodes of the linearized equations. The magnetohydrodynamic equations are derived from nonequilibrium thermodynamic principles. It is pointed out that a minimal set of phenomenological coefficients are found in this manner. The magnetohydrodynamic equations are linearized and then solved for the magnetohydrodynamic eigenmodes in the two special cases of the wave vector k parallel and perpendicular to the external magnetic field.
Studies on the Moments of Inertia of Light Nuclei. Part I. Calculations in the sd Shell Using Skyrme-type Formulas
Authors: Ng W. Y. , Trainor L. E. H.
Published: October 2017

The Hartree–Fock–Skyrme approach to calculations of the nuclear moment of inertia is generalized. It is shown that a different formula than the usual Skyrme formula can be expected to give better results. This result is illustrated by calculations on even–even nuclei in the sd shell.
The d3Σ–a3Πr Transition of SiO
Authors: Singh M. , Bredohl H. , Remy F. , Dubois I.
Published: October 2017

The triple headed and violet degraded band of SiO at 2970 Å has been excited in a high frequency discharge through a mixture of SiCl4, oxygen, and argon flowing at low pressures. From a study of the high resolution spectrum, this band has been assigned to a 3Σ–3Π transition. The final state has been identified with the well known a3Πr state of SiO, and the initial state has been designated as the d3Σ and located at 33 640 cm−1 above the a3Πr. The rotational constants determined for the d3Σ state are (in cm−1):

[Formula: see text]
Inelastic Collisions Between Excited Alkali Atoms and Molecules IX. An Isotope Effect in the Cross Sections for 62P1/2↔62P3/2 Mixing in Cesium, Induced in Collisions with Deuterated Methanes
Authors: Walentynowicz E. , Phaneuf R. A. , Baylis W. E. , Krause L.
Published: October 2017

The temperature dependence of cross sections for 62P1/2 ↔ 62P3/2 mixing in cesium, induced in collisions with CH4, CH3D, CH2D2, CHD3, and CD4 molecules, has been investigated in a series of sensitized fluorescence experiments over a temperature range 290–650 K. The various cross sections which are of the order of 10−15 cm2, and which exceed similar cross sections for cesium–noble gas collisions by 4 – 6 orders of magnitude, exhibit differences in their variation with temperature. This isotope effect in the collision cross sections is interpreted on the basis of a novel semiclassical theory of electronic to rotational energy transfer. The cross section for mixing induced by collisions with CF4, which was determined in a subsidiary experiment, and which is 2–3 times larger than the methane cross sections, does not show comparable behavior with temperature, probably because the energy transfer takes place to closely lying molecular vibrational states.
A Search for Isobaric Analogs of 209Tl as Resonances in the Isospin Forbidden 208Pb(n,p)208Tl Reaction
Authors: Long D. D. , Onega R. J. , Lee S. T.
Published: October 2017

A search was made for isobaric analogs of levels in 209Tl via the 208Pb(n,p)208Tl reactions, which is isospin forbidden in the entrance channel. No evidence is found for the existence of such resonances in 209Pb.
On Flows Behind Hydromagnetic Shock Waves
Authors: Upadhyaya K. S. , Pandey R. K.
Published: October 2017

The effects of the thermodynamical behavior of the fluid on vorticity and current density generated behind magnetogasdynamic shocks have been discussed in detail. It has been observed that in general, the vorticity and current density are not independent of the thermodynamical behavior of the fluid, but in some particular cases they can be obtained purely from dynamical considerations.
Elastic Scattering and Rotational Excitation of Molecular Hydrogen by Low Energy Positrons
Authors: Baille P. , Darewych J. W. , Lodge J. G.
Published: October 2017

The adiabatic nuclei approximation is used to study low energy positron collisions with hydrogen molecules. The interaction of the positrons with the hydrogen molecules is represented as a superposition of electrostatic and polarization potentials. Total and differential elastic and momentum transfer cross sections are calculated. The effect of small variations in the potentials, and the convergence of the partial wave expansion are discussed. The annihilation rate of the positrons is calculated with and without incorporating the effect of distortion of the electron cloud by the incoming positrons. Rotational excitation cross sections, both differential and total, are presented. The results are compared, where possible, to recent similar two-center calculations of Hara, and experimental results of Coleman et al.
Temperature Dependence of the Exchange Splitting in Ferromagnetic Metals I. Information from the de Haas–van Alphen Effect in Iron
Authors: Lonzarich G. , Gold A. V.
Published: October 2017

High resolution measurements of the de Haas–van Alphen frequency associated with the minority-spin electron 'lens' sheets of the Fermi surface of iron have been carried out between 1 and 4.2 K. The variation of the frequency over this temperature range is found to be less than one part in 105 (the resolution of our experiment) and is virtually identical to that found for the corresponding electron lenses in molybdenum. By contrast, a variation of one part in 104 would be expected for the Fe lenses on the basis of a literal interpretation of the Stoner model, in which the exchange splitting of the energy bands is proportional to the magnetization at all temperatures. The absence of any significant change of the frequency with temperature can be understood if the magnetization decreases almost entirely by spin wave excitations, and if the spin waves have negligible effect on the exchange splitting.
Strain Induced Potentials on a 'Dirty' Polycrystalline Surface
Authors: Enga Eric
Published: October 2017

General considerations are given as to the nature of five mechanisms which can produce strain induced potentials on a metal surface. Some experimental evidence is included. This is of interest in the question of the strain dependence of contact potential, and may be of interest in the metallurgy of surfaces.
Magnetoconductivity of Indium
Authors: Douglas R. J. , Datars W. R.
Published: October 2017

The components of the electrical magnetoconductivity and magnetoresistivity tensors of indium were calculated by the path integral method with a formulation used previously for aluminum. Results presented for longitudinal and transverse magnetoresistance, the longitudinal–transverse components and the Hall term are compared with previous calculations for aluminum and with available experimental results of indium. The magnetoconductivity of aluminum for a four orthogonalized plane wave (OPW) pseudopotential Fermi surface model is reported for comparison with the single OPW calculations.
Free to Bound Recombination and Screening Effects in CdS
Authors: Egloff R. M. , Colbow K.
Published: October 2017

The luminescence spectrum of CdS consists of a number of sharp lines from 2.43 eV to the band edge at 2.58 eV and a number of broad bands below 2.43 eV. The highest energy broad band is due to a free electron recombining with a hole bound at a shallow acceptor (free to bound). The dependence of the free to bound peak of energy on temperature and excitation intensity is investigated in the interval 4.2–80 K. Increasing the excitation intensity results in a shift to higher energy. This is interpreted in terms of free carrier screening which reduces the binding energy of the acceptor. An energy shift due to the recombination of hot electrons is also considered. An often neglected donor–acceptor interaction term is discussed and found to be significant for an accurate measurement of the acceptor binding energy. Experimental observations suggest that screening of excitons due to free carriers is ineffective.
Numerical Evaluation of Partial Wave Contributions to Pion–Nucleon Amplitudes
Authors: Brunet Robert C.
Published: October 2017

We present detailed numerical evaluations of the partial wave projections of Feynman diagrams of second- and fourth-order in perturbation for the πN–πN scattering in the [Formula: see text] theory. Perturbative contributions to the S, P, and D waves of isospin 1/2 and 3/2 are given in tables of numerical values. Figures regrouping these results show surprising behavior for the ratios Re(4)/Re(2). These tables and figures allow easy calculations with models using low order perturbation terms such as Padé approximants.
Photoconductivité dans l'alliage GaAsxSb1−x en présence d'un champ magnétique
Authors: Filion A. , Fortin E.
Published: October 2017

The intrinsic photoconductivity of several samples of the alloy GaAsxSb1−x has been studied at 4.2 K in the presence of magnetic fields of up to 65 kG. Values for the band-gap, the reduced effective mass of the carriers, the energy of the longitudinal optical phonons across the alloy composition are deduced from the measurements.
Plane Magnetofluiddynamic Flows with Constantly Inclined Magnetic and Velocity Fields
Authors: Toews H. , Chandna O. P.
Published: October 2017

Plane steady state nondissipative compressible fluid flows, in which the conductivity is infinite and in which the magnetic field and the velocity field are constantly inclined to one another, are considered. Sonic flows, and flows for which the velocity is constant along each streamline, are studied and the related results are applied to flows in poly-tropic gases. It is shown that if two distinct incompressible flows have the same streamline pattern, then the flow variables are related in a definite manner. Finally, solutions are obtained for vortex flows and also for parallel flows.
Long Wavelength Bound Exciton Emission in CdS
Authors: Smeaton M. D.
Published: October 2017

Our investigations of CdS single crystals at low temperatures (~5 K) have uncovered a series of sharp luminescent lines in the wavelength region 5050 to 5150 Å, including two transitions originally reported by Reynolds and Litton. Excitation spectra of these long wavelength lines have enabled us to find a close relationship between the various transitions. We believe that they result from the radiative decay of two distinct bound exciton complexes, which we have labeled I6 and I7, in the notation of Reynolds and Litton. These complexes are probably formed from excitons bound to deep impurities in CdS. Results of the excitation spectra have also suggested the presence of a resonance exciton transfer mechanism from the I2 complex (exciton bound to a shallow neutral donor) to the more strongly bound state represented by the I6 complex. We have investigated the effects of variations in excitation intensity and sample temperature on the long wavelength lines, and have measured a thermal activation energy of 43.2 ± 0.2 meV for I6a, a transition of the I6 complex. On the basis of our experimental results we have constructed a tentative energy level diagram for decay of the I6 bound exciton.
Decay of 143Eu
Authors: Kennedy G. , Gujrathi S. C. , Hinrichsen P. F.
Published: October 2017

A high resolution study of γ-ray transitions in 143Sm following the β+ decay of 143Eu has been made using Ge(Li) detectors. Fifty-seven γ rays are assigned to the decay of 143Eu, and the ground state spin of 143Eu is established as 5/2+. Spin and parity assignments are made on the basis of γ-ray branching, deduced log ft values, and by comparison with previous (p,d) reaction data. Good agreement between experiment and predictions of the intermediate coupling model suggests that this model adequately accounts for the low lying levels of 143Sm.
The Spectroscopy of Pr3+ Ions in Aprotic Solvents
Authors: Watanabe A.
Published: October 2017

Experimental results are reported for a spectroscopic study of Pr3+ ions dissolved in aprotic solvents. A spectroscopic determination of the induced emission cross section for the 3P0 → 3F2 and 3P0 → 3H6 transitions is described; the values obtained were 4.3 × 10−19 cm2 and 2.0 × 10−19 cm2 respectively. Mechanisms for the nonradiative quenching of the fluorescence of the 3P0 level are discussed; radiative efficiency of the 3P0 level was 9.6 × 10−2.
Gravitational Radiation and Its Detection
Authors: Papini G.
Published: October 2017

A review is presented of the theoretical and experimental aspects of the field of gravitational radiation. This article, aimed particularly at showing that the problem of gravitational radiation can be tackled experimentally in various meaningful ways, includes, for completeness, a short theoretical introduction and a discussion of possible radiation sources. Several detection schemes are discussed and the experimental situation is reviewed, with attention to the questions it raises.
Electrodynamics and Propagation of a Spin 3/2 Field
Authors: Capri A. Z. , Shamaly A.
Published: October 2017

We show that if a charged Rarita–Schwinger spin 3/2 field is coupled both to an internal as well as external electromagnetic field, acausal propagation will always occur regardless of the external field. Thus the electrodynamics of a Rarita–Schwinger spin 3/2 field is not consistent with special relativity.
The Spectra of Diatomic Molecules; A Bibliography 1960–1970
Authors: Suárez Carlos B.
Published: October 2017

A bibliographic compilation of diatomic molecular spectra for the period 1960–1970, listing about 4000 papers, has been deposited with the National Science Library, National Research Council of Canada, Ottawa, Canada.
The Size Dependence of the Melting Point of Small Particles of Indium
Authors: Berman R. P. , Curzon A. E.
Published: October 2017

A Philips E.M. 300 electron microscope operating in the dark field high resolution mode has been used to study the size dependence of the melting points of individual particles of indium. The straight line graph, obtained from a simple thermodynamic treatment of the results, shows that the surface tension at the interface between solid and liquid indium is σ1 = 101 ± 10 dyn/cm.

Similar experiments were carried out on tin so that the results of the present experiments could be compared with those of other workers. The value of the interfacial surface tension was σ1 = 69 ± 6 dyn/cm.
Sensitized Fluorescence in Vapors of Alkali Atoms XIV. Temperature Dependence of Cross Sections for 72P1/2–72P3/2 Mixing in Cesium, Induced in Collisions with Noble Gas Atoms
Authors: Siara I. N. , Kwong H. S. , Krause L.
Published: October 2017

The cross sections for 72P1/2–72P3/2 excitation transfer in cesium, induced in collisions with noble gas atoms, have been determined in a series of sensitized fluorescence experiments at temperatures ranging from 405 to 630 K. The cross sections which lie in the range 0.06–20 Å2, exhibit a temperature dependence which, however, is less pronounced than in the more adiabatic case of the cesium resonance doublet.
Response Functions of Cosmic Ray Muon Telescopes at Sea Level and at 60 m.w.e.
Authors: Hicks R. B. , Simpson G. , Mathews T.
Published: October 2017

A theoretical determination of the primary response of cosmic ray muon telescopes is presented. The calculations take into account successive collisions of an incoming primary nucleon, the distribution in energy of pions and muons at generation, and the decay and energy loss of muons in the standard atmosphere. Values of the primary muon multiplicity are given for telescopes at sea level and at a depth of 60 m.w.e. underground. The response functions obtained are verified by comparison with experimental data on the latitude effect and equatorial east–west effect at sea level. Comparisons are also made with response functions proposed by other workers for telescopes at 60 m.w.e.
Conduction Electron Contributions to the Crystalline Electric Fields in Transition Metals
Authors: Ludwig A. , Devine R. A. B.
Published: October 2017

We discuss the origin of the crystalline electric fields for rare earth ions in transition and noble metal hosts, in terms of the band character of the host material and of localization and delocalization of 5d electrons on the rare earth ions. A tentative explanation is given for the almost pure negative point charge character found in Pd and Pt.
Lie Groups and the Jahn–Teller Effect
Authors: Judd B. R.
Published: October 2017

After an introduction to the classic theory of the Jahn–Teller effect for octahedral complexes, an account is given of Lie groups and their relevance to the F+ center in CaO. The coincidence of the three-fold and two-fold vibrational modes (both of angular frequency ω) leads to a study of U5 and R5, the unitary and rotation groups in five dimensions. The language of second quantization is used to describe the weight spaces and branching rules. Pairs of annihilation and creation operators for phonons are coupled to zero angular momentum and used as the generators of the noncompact group O(2, 1). This facilitates the evaluation of matrix elements of V, the interaction that couples the oscillations of the octahedral complex to the electron in its interior. Glauber states are used near the strong Jahn–Teller limit, corresponding to [Formula: see text]. The possible extension of the analysis to incorporate the breathing mode is outlined. Correspondences with problems in nuclear physics are mentioned.
Positron–Helium Scattering Cross Sections and Phase Shifts Below 19 eV: Addendum
Authors: Jaduszliwer B. , Paul D. A. L.
Published: October 2017

We have extended the phase shift analysis of our positron–helium transmission experiments to determine the importance of cross correlation between the s and p wave phase shifts in a previous paper. We have found out that using Humberston's s wave phase shifts with suitably modified p and d wave phase shifts leads to as good a fit to our experimental data as Drachman's s wave phase phase shifts.

Preliminary values of total cross section are given in the 19 to 27 eV energy region.
The Ion Current Density on the Surface of a Spherical Probe in a Flowing High Pressure Plasma
Authors: MacLatchy C. S. , Budgel P. C. , Miner J. R.
Published: October 2017

The positive ion current density on the surface of a spherical probe immersed in a flowing flame plasma has been measured under thin sheath conditions. The hydrodynamic Reynolds number ranged from 96 to 720. No pronounced real fluid effects have been observed in the current density although the probe is observed by Schlieren photography to exhibit boundary layer separation and wake formation. In spite of the real fluid behavior of the plasma fluid, the thin sheath theory describes the current density distribution on the probe surface very effectively. This is attributed to the formation and entrainment of a shielding layer of fluid, voided of charge during its passage through the sheath.
ZnO Thin Films and Their Application to Germanium Acousto-optic Modulators
Authors: Hillman G. D. , Seguin H. J. J.
Published: October 2017

The deposition system and parameters for repeatably producing highly oriented ZnO thin films suitable for high frequency acousto-electric transducers are described. At the high super-saturations used the state of the nucleating surface and the partial pressure of oxygen, in the sputtering gas mix, are shown to critically affect the texture and stress level in the film.

The performance of a germanium acousto-optic modulator employing a ZnO thin film transducer is compared with that expected theoretically. The photoelastic constant of germanium at 10.6 μ is shown to be 0.42 ± 0.05. The analysis indicates that a germanium acoust-ooptic modulator could be used to efficiently couple energy out of a CO2 laser.
Magnetohydrodynamic Flow Past a Finite Flat Plate in the Presence of a Nonaligned Magnetic Field
Authors: Lakin W. D.
Published: October 2017

We consider the steady flow past a finite flat plate due to a uniform stream in the presence of a uniform magnetic field which is not aligned with the streaming motion at infinity. The Hartmann number is assumed large and positive. This leads to a singular perturbation problem involving a second-order partial differential equation. As a result, solutions of the governing equation must be obtained in three separate regions and then matched asymptotically. A related problem involving magnetohydrodynamic (MHD) flow across a finite needle is also discussed.
The Absorption Spectrum of D2 from 1100 to 840 Å
Authors: Dabrowski I. , Herzberg G.
Published: October 2017

The absorption spectrum of D2 has been studied in absorption at high resolution (0.254 Å/mm) in the region 1100 to 840 Å. The three band systems B1Σu+ ← X1Σg+ (Lyman bands), B′ 1Σu+ ← X1Σg+ and C1Πu ← X1Σg (Werner bands) have been measured right up to the dissociation limit. New improved values of the rotational and vibrational constants in the three upper states have been derived. By comparing the electronic energy differences Tc thus obtained with the corresponding values for H2 fairly precise values for the electronic isotope shifts for the B–X and C–X systems have been determined (+ 2.8 and −7.4 cm−1 respectively). In this connection two gaps in the knowledge of the absorption spectrum of H2 have been filled: the Lyman bands with ν′ = 5–16 and the Werner bands with ν′ = 0–4 (see Appendix).

A detailed comparison is made of the observed vibrational levels and the observed Bν values of D2 with those derived from ab initio calculations based on the Kotos and Wolniewicz' potential functions. From the observed electronic isotope shift the adiabatic corrections can be estimated near the minimum. For the B state these estimates agree very well with the ab initio calculations. The remaining differences between observation and theory are partly due to lack of convergence of the Born–Oppenheimer calculation, partly to the neglect of nonadiabatic corrections. The convergence error near minimum is estimated to be 5.1 cm−1 for the B state and 1.2 cm−1 for the C state.
Regge Pole Plus Background Model of Backward πp Scattering
Authors: Kogitz S. , Logan R. K.
Published: October 2017

We present a model of backward π+p, π−p, and π−p charge exchange scattering consistent with our earlier approach to forward π−p charge exchange and backward π+p. We consider two body differential cross section data which exhibits a dip–bump structure as well as nonzero polarization. This is explained in terms of a dominant Regge pole vanishing at the dip accompanied by a background. The background is primarily responsible for the large u behavior of the cross section which includes the rise after the dip. It is assumed that the presence of nonzero polarization dictates this behavior. We isolate the I = 3/2 amplitude in π−p backwards and determine the I = 1/2 amplitude from π+p backwards. A prediction for π−p → nπ0 follows.
Spin Determinations in Low Lying States of 151Sm
Authors: Singh B. , Johns M. W.
Published: October 2017

Gamma–gamma directional correlation measurements together with parity assignments based on the published literature have been used to make the following Jπ assignments in 151Sm: Jπ = 3/2+ for the 307, 345, 521, 741, 823, and 953 keV states, Jπ = 5/2+ for the 167, 396, and 446 keV states, and Jπ = 7/2+ for the 324 keV state. In addition, somewhat less secure assignments of 3/2−, 7/2−, 5/2+ (or 3/2+), and 5/2+ have been made to the 105, 209, 774, and 878 keV states respectively. The multipole mixing ratios of the 65, 66, 70, and 105 keV transitions are negative and the observed values of δ are compared with [Formula: see text] values obtained from L subshell conversion measurements.
Photovoltaic Effect of a Au–Ge Barrier in a Quantizing Magnetic Field
Authors: Rochon P. , Fortin E.
Published: October 2017

A study is made of the oscillatory spectral distribution of the photovoltaic effect of a gold–germanium Schottky barrier in quantizing magnetic fields. The spectra are taken at 4.2 K in the Faraday configuration for fields of up to 70 kG. The results are analyzed in terms of the Pidgeon and Brown coupled bands theory of interband magneto-absorption. Excitonic effects are observed and discussed.
High Resolution Electron Spectrometry in Neon
Authors: Roy D. , Carette J.-D.
Published: October 2017

High resolution electron spectrometry has been applied in measurements of excitation of neon by electron impact. In the analysis of the energy loss spectra, many electronic states of neon have been evidenced; a great number of them had not been resolved by this investigation tool so far. Moreover, the relative heights of these loss peaks, corresponding to single defined electronic states, have been studied as a function of energy of incident electrons and scattering angle at which the energy analysis is carried out.
Vibronic Sideband of Er3+ in CaF2
Authors: Ward R. W. , Whippey P. W.
Published: October 2017

Measurements of the low temperature luminescent spectra of CaF2:Er3+ have revealed a vibronic sideband associated with the Er3+ electronic transition at 5512 Å. The phonon frequencies observed are shown to be related to the single phonon density of states of CaF2.
Eddy Current Distribution and Lift Force for Finite Maglev Strips
Authors: Atherton D. L. , Eastham A. R. , Fombrun C. , Chong M.
Published: October 2017

The transverse distribution of induced eddy currents across a flat conducting strip of finite width, due to a rectangular d.c. magnet moving above it, has been modelled experimentally, and has been compared with that calculated for an infinite sheet. The electrodynamic suspension was simulated by means of a stationary a.c.-excited copper magnet suspended above an aluminum strip, and the induced surface current density was measured by a voltage pickup probe connected to a lock-in amplifier. Good agreement is obtained between the eddy current profiles for a wide sheet and those calculated by determining the current distribution required to cancel the vertical component of the magnet field at the surface of the sheet. The effect of reducing strip width is examined and shown to produce high current densities close to the edges. These results are related to the variation of lift force with strip width, determined by impedance modelling. A slight enhancement of lift is evident for intermediate strip widths.
Spin–Orbit Coupling Force Effects in Giant Excitations of Doubly Closed Shell Nuclei
Authors: Ledoyen F.
Published: October 2017

We show that the spin–orbit coupling force may induce axial excitations higher in energy than the vector ones in muon capture without necessarily having [Formula: see text].
Light Diffraction Studies of CdS Phonon Masers: Off-Axis Cavity Structures
Authors: Vrba J. , Haering R. R.
Published: October 2017

Light diffraction experiments on CdS phonon masers whose cavity normal is oriented at 15, 30, 45, 60, and 75° to the crystallographic c axis are presented and compared with theory. It is shown that in general the acoustic waves do not propagate along the direction of the cavity normal. An interpretation of the observations requires that one takes into account the acoustic anisotropy and the effect of mode conversion at the cavity walls.
Experimental Mean Lives for Mn I, II, and III, and Their Implications for a Revised Manganese Solar Abundance
Authors: Pinnington E. H. , Lutz H. O.
Published: October 2017

A discussion is presented of beam foil mean lives for 9 terms of Mn I, 5 terms of Mn II, and 4 terms of Mn III. Attention is given to the energy loss sustained by the ions in the foil and to the limitations imposed by the finite time resolution of the technique. Transition probabilities derived from these mean lives are compared with those obtained by a variety of experimental and theoretical techniques; generally good agreement was obtained with values previously suggested by Allen, by Martinson et al., by Blackwell and Collins, and by Woodgate. Our values are also used, in conjunction with several curves of growth discussed in the literature and a new branching-ratio measurement, to derive a revised value of the photospheric abundance of manganese given by log N(Mn) = 5.34 ± 0.08.
Spectroscopic Study of 32S Through the 31P(d,n)32S Reaction
Authors: Hussein A. H. , Neilson G. C. , McDonald W. J. , Dawson W. K.
Published: October 2017

The 31P(d,n)32S reaction has been studied at deuteron energies of 4.0 and 5.45 MeV. Neutron energies were measured by time of flight. Absolute differential cross sections of seven levels in 32S have been measured and compared with the theoretical predictions of both the DWBA and compound statistical theories. Analysis of the angular distributions yielded lP values and absolute spectroscopic factors. These results have been compared with those from other experiments and shell model predictions.
High Field Induced Torques and the Fermi Surface of Osmium
Authors: Plachy A. L. , Dixon A. E.
Published: October 2017

The Fermi surface of osmium has been investigated using the induced torque technique at high magnetic fields. This is believed to be the first report of an induced torque experiment performed on a low conductivity sample and in the high fields of a superconducting magnet. Open orbits were found for B along [Formula: see text]. These orbits continue to be seen as the magnetic field is tilted to at least 65° from the basal plane. The dependence of the open orbit torque on magnetic field strength, rotation rate, and tilt angle was studied. No open orbits were found for B along [Formula: see text]. Torques due to closed orbits were also studied, and comparison of the predictions of the free electron model is given for these torques. A maximum in the torque is seen for B along [0001], and an explanation is suggested for this behavior.
Ground State Radiation Width of the 10.18 MeV, Jπ = 3−, State in 28Si Deduced From 100 MeV Proton Inelastic Scattering
Authors: Horowitz Y. S.
Published: October 2017

Differential cross section data for 100 MeV protons inelastically scattered from 6Li, 9Be, 12C, 24Mg, and 28Si are compared with the corresponding E2 and E3 transition rates and a strong correlation is shown to exist between (dσ/dΩ)max and Γγ0 if the shape of the proton angular distribution is characteristic of single excitation. The persistence of the correlation to transitions with Γγ0/Γγ < 0.1 allows an estimate of Γγ0 = 8.6 ± 5 × 10−4 eV for the 10.18 MeV, Jπ = 3−, level in 28Si.
Resonant Pair–Modes in KI:Rb+
Authors: Ward R. W. , Clayman B. P.
Published: October 2017

Using a molecular model, we have calculated the resonant mode frequencies of tetragonal [110] and rhombic [100] aligned Rb+ pairs in KI. The frequencies are found to lie both in the phonon gap and in the acoustic continuum. The results are discussed in relation to the recent work of de Jong et al. on this system.
Superconductivity in Single Crystal Tl
Authors: Truant P. T. , Carbotte J. P.
Published: October 2017

We have used a model of the electron–phonon interaction in Tl which is consistent with neutron scattering data on the phonon dispersion curves as well as the superconducting tunneling data on the isotropic electron–phonon function α2(ω)F(ω) to explore the amount of anisotropy that can be expected in select properties of Tl. First the Fermi surface (FS) variation of the electron mass renormalization parameter λ(k) is determined. Then the superconducting gap Δ(k) is obtained for many k's on the FS. The mean square gap anisotropy is calculated. The pure single crystal transition temperature is obtained and compared with the dirty limit.
Contribution to the Theory of Transport in Dilute Metallic Alloys
Authors: Kus F. , White B. A. , Mason J. , Carbotte J. P.
Published: October 2017

We present the results of numerical calculations of the electrical and thermal resistivities of dilute alloys of alkali metals, based on the theory of Kagan and Zhernov. A realistic description of the phonon spectrum and the electron–ion form factors is employed; numerous recent calculations have indicated that this is necessary in order to obtain even semiquantitative values for the ideal pure crystal electrical resistivity. Our results are an extension of the recent pure crystal work to dilute alloys, and should be a great improvement on previous approximate calculations.
Longitudinal Relaxation Time Measurements in Hydrogen Gas at Low Densities
Authors: Kisman Kenneth E. , Armstrong Robin L.
Published: October 2017

Measurements of the nuclear spin longitudinal relaxation time through the region of the characteristic minimum at 49.0 MHz in molecular hydrogen are reported at 77.5, 296, and 385 K. At 77 K molecular hydrogen may be treated as a single J-level quantum system. The experimental measurements serve to check the basic approximations in the Bloom–Oppenheim relaxation theory. The present data show that the ratio τsr/τd of the correlation times associated with the spin–rotation and dipolar interactions lies in the range from 0.58 to 0.83; the theoretical prediction is 0.6. At 296 and 385 K molecular hydrogen may be treated as a two J-level quantum system. Starting from the Bloom–Oppenheim theory it is possible to express the contribution to the transition rate from collisions which cause transitions between the J states to that which causes transitions within a J manifold in terms of a parameter R. The present experiments are consistent with R values in the ranges 1 < R < 10 at 296 K and 0.6 < R < 20 at 385 K.
The Half-Life of the 379.3 keV State of 169Tm
Authors: Bodenstedt E. , López-García A. R. , Martínez J. A. , Mendoza-Zelis L. A. , Caracoche M. C.
Published: October 2017

The half-life of the 379.3 keV state of 169Tm has been reinvestigated by the delayed coincidence technique. The result, T1/2 = 49.8 ± 1.5 ns is about 40% larger than the result by Berlovich et al. which had been generally accepted in the literature.
Determination of Size, Size Distribution, and Refractive Index of Dow Latexes EP-1358-38 by the Mie Scattering Method
Authors: Robillard F. , Patitsas A. J.
Published: October 2017

Mie scattering at two different wavelengths was used to determine the size, the size distribution, and the refractive index of Dow latexes EP-1358-38. Computer calculated scattering curves were obtained for three size dispersions and three refractive indices. The experimental scattering curves were compared with the calculated curves in order to find the combination of refractive index and size distribution for which the agreement between the experimental data and the computed values was optimized.
On the Absence of Bound States in the λϕ24 Quantum Field Model Without Symmetry Breaking
Authors: Feldman Joel
Published: October 2017

We study a λϕ24 model with a unique vacuum, invariant under the symmetry ϕ → −ϕ, and we assume that certain connected 4n-point Euclidean Green's functions are negative. Then the mass operator, M = (H2 – P2)1/2, restricted to the space of states that are even under ϕ → −ϕ, has no spectrum in the interval (0, 2m). In particular, two particle bound states do not occur in the single phase region (i.e. λ < λcritical).
Pressure Dependence of the de Haas – van Alphen Effect in Ytterbium
Authors: Slavin A. J. , Datars W. R.
Published: October 2017

The de Haas–van Alphen effect and the h.c.p.–f.c.c. phase transformation of ytterbium were studied with the magnetic field along the [0001] direction in the h.c.p. phase, using pressures up to 4 kbar. Solid helium was used as the pressure medium. The pressure dependence of the three dHvA frequencies in the h.c.p. phase for the [0001] magnetic field direction was linear within experimental error with dF/dP = −1.2 ± 0.2 T/kbar for F(P = 0) of 35.4 T, dF/dP = 0.30 ± 0.03 T/kbar for F(P = 0) of 142.5 T, and dF/dP = −0.78 ± 0.10 T/kbar for F(P = 0) of 156.4 T. The dHvA amplitude in the h.c.p. phase was independent of pressure up to the phase transition and no dHvA effect was observed in the f.c.c. phase. The pressure of the phase transformation at 1.2 K was determined to be 2.15 ± 0.05 kbar.
Transfer of Electronic Excitation between the 62P3/2 and 62P1/2 States of Rubidium Induced by Collisions with Rubidium Atoms
Authors: Pace Paul W. , Atkinson J. B.
Published: October 2017

The cross sections for excitation transfer between the 62P fine structure levels of rubidium, induced in collisions with ground state rubidium atoms, have been measured using a nitrogen laser pumped dye laser as the optical excitation source in a fluorescence experiment. Rubidium vapor was irradiated with each component of the 2P rubidium doublet in turn, and measurements of the relative intensities of fluorescence yielded the following cross sections:

[Formula: see text]

These results are consistent with the empirical relationship between the magnitude of the cross sections and the fine structure splitting that has previously been established for the alkalis.
A Born–von Karman Force Constant Model for Aluminum
Authors: Cowley E. R.
Published: October 2017

A Born–von Karman force constant model of aluminum, fitted to the frequencies of normal modes with wave vectors distributed throughout the Brillouin zone, is described, and the frequency distribution function calculated. The result is in very good agreement with a distribution function calculated directly from the experimental data.
Rectification of Acoustic Waves
Authors: Mathur S. S. , Sagoo M. S.
Published: October 2017

The difference in the behavior of the denser and the rarer regions of a longitudinal travelling acoustic wave is utilized to produce the phenomenon of rectification of ultrasonic waves. It has been shown that, under appropriate conditions, the energy density of sound in the regions of rarefaction can be increased while in the regions of compression the energy density is decreased. It is found that under suitable conditions, the pressure amplitude in the rarer regions is about 4% larger than that in the denser regions. The measurement of this difference in amplitude can be used to determine the parameter of nonlinearity.