bluuebunny/crossref_metadata_2025 huggingface dataset:
Inelastic Neutron Scattering in the Region A = 11–40
Authors: Nichol L. , Kennett T. J.
Published: April 2011

The (n,n′γ) reaction has been studied for the nuclides 11B, 14N, 19F, 23Na, 27Al, 28Si, and 40Ca through the use of fission-spectrum neutrons. The gamma-ray spectra obtained using a Ge(Li)–NaI(Tl) split-annulus spectrometer revealed that levels up to 9 MeV are populated. Analysis of the gamma-ray spectra permitted the derivation of decay schemes and, from the branching, the primary population of each level observed. Assuming an exponential form for the reactor fission-spectrum neutrons, a model based upon the Hauser–Feshbach formalism was employed to calculate the relative population expected for each level using previously reported Jπ values. The validity of the model and the reliability of obtaining spin information is examined.
Nuclear Spin–Lattice Relaxation in Superconducting Al
Authors: Carbotte J. P. , Truant P. T.
Published: April 2011

We have calculated the temperature variation of the nuclear spin–lattice relaxation rate in superconducting aluminum taking account of the anisotropy in the energy gap that Leavens and Carbotte have recently calculated from microscopic theory. We compare this variation with the available experimental data for the region near the critical temperature.
Nuclear Magnetic Resonance and Quadrupole Coupling in Hydrous and Anhydrous Sodium Molybdate and Sodium Tungstate Spinel
Authors: Lynch G. F. , Segel S. L.
Published: April 2011

The nuclear magnetic resonance of 23Na in powder samples of hydrous and anhydrous sodium molybdate and sodium tungstate has been investigated. The anhydrous compounds crystallize in the cubic spinel of type H11, Fd3m presumably with ionic charges of 1 + and 6 + on the metals. The 23Na quadrupole couplings are the largest yet observed for this nucleus and have values of 2.62 and 2.48 MHz in the molybdate and tungstate respectively, as determined from both first- and second-order effects on the magnetic resonance spectrum. These couplings have negligible temperature dependences. Using charges of 1 + and 6 + for the metal ions, assuming that the oxygens are in their ideal positions in the spinel structure and neglecting any contributions from oxygen dipoles and quadrupoles, the electric field gradient was calculated to be 12 × 1013 e.s.u./cm3, in good agreement with the experimental gradient of 7.5 × 1013 e.s.u./cm3. Preliminary measurements of the sodium spin–lattice relaxation time, using tone-burst techniques, indicated a value between 30–60 s. The 95.97Mo nuclear resonances were also observed in the molybdate and these resonances showed no quadrupole effects.
Solution of an Infinite Set of Green-Function Equations for a Trapped Electron
Authors: Frank B. , Cheung C. Y.
Published: April 2011

A Gaussian line shape is obtained for absorption of light by a single trapped electron, interacting linearly with the lattice vibrations, by solving an infinite set of double-time Green-function equations valid to lowest order in the adiabatic approximation. It is assumed that the phonons do not mix different electronic states. The result is the same as that obtained by applying the strong-coupling approximation to the exact Fourier-transformed expression, and can be extended to the case of a more general Hamiltonian.
Analysis of Wide Lorentzian-Shaped Electron Spin Resonance Lines
Authors: Hedgcock F. T. , Raudorf T. W.
Published: April 2011

Significant distortion of ESR line shapes can result when the half-power line width is comparable to the magnetic field at resonance. Unless adequate compensation is made, this distortion leads to errors in measuring the resonance field and the line width. These corrections are derived explicitly for a Lorentzian line shape and illustrated by experimental data for Mn-doped GeTe.
Double-Discharge TEA Laser Beams
Authors: Fortin R. , Laflamme A. K. , Rheault F.
Published: April 2011

The energy and power density distributions of a multi-transverse-mode laser beam are predicted from a simple theoretical model. The corresponding experimental verifications show a good agreement for both the near- and far-field behavior of these beams. Finally, a method for optimizing the peak power density in the focal volume of a converging element is suggested.
Temperature Dependence of the Hyperfine Field at 181Ta Nuclei in a Nickel Lattice
Authors: Barrett J. S. , Cameron J. A. , Zâmori Z. , Santry D. C.
Published: April 2011

The temperature dependence of the magnetic field at 181Ta nuclei in a nickel lattice has been determined by time-differential perturbed angular correlations. Results consistent with nonmagnetic impurity behavior were obtained.
The Nuclear Repulsive-Core Effect as a Possible Consequence of Matter in Interaction with a Classical Relativistic Scalar Field: A New Approach to the Question
Authors: Leiter D. , Huschilt J. , Szamosi G.
Published: April 2011

The N-body problem is analyzed within the framework of a new formalism for relativistic point masses interacting via a scalar field, in which the problems of infinite self-energies are absent. A Lagrangian formalism is exhibited which yields the particle equations of motion in the form of a parameterized class of equations. The parameter determines the choice of boundary conditions which is chosen on the scalar-field equations. The existence or nonexistence of the relativistic nuclear hard-core effect, associated with the scalar-field interactions, is shown to depend critically on the particular set of boundary conditions which are imposed on the scalar-field equations. In particular, time-symmetric boundary conditions yield no hard-core repulsion, while retarded boundary conditions are shown to yield a hard-core repulsion at very short range.
An Examination of the Relationship between Sound Velocity and Density in Liquids
Authors: Aziz Ronald A. , Bowman D. H. , Lim C. C.
Published: April 2011

The "constants" of Rao and of Carnevale and Litovitz are re-examined and their similarity to a pseudo-Grüneisen parameter is demonstrated. Another empirical relationship, viz. the velocity of sound in liquids as a linear function of density, is presented. Extrapolations of such a relationship might prove useful in the study of the velocity of sound in the critical region and in the polycrystalline solid at 0 °K.
Geometric-Mean Wave Function for HeH2+
Authors: Lam C. S. , Varshni Y. P.
Published: April 2011

A geometric-mean type of variation function has been examined for the 1sσ state of HeH2+ and has been found to give very good results for the energy.
The Law of Corresponding States as Applied to Sound Velocity in Liquids Consisting of Elliptical Molecules
Authors: Poole G. R. , Aziz Ronald A.
Published: April 2011

The velocity of sound was measured in liquid ethane, under saturated vapor, in the normal liquid range by a resonance technique.With the use of existing velocity data for argon, nitrogen, and oxygen, a modified form of the corresponding-states principle was applied to the elliptical molecules, oxygen, nitrogen, and ethane. Good correspondence was found for reduced temperatures less than one (T* < 1).
The Magnetic Field at Tungsten Nuclei in Iron
Authors: Cameron J. A. , Keszthelyi L. , Mezei G. , Szökefalvi-Nagy Z. , Varga L.
Published: April 2011

Larmor precession of the first 2+ states of 182W and 184W has been observed in an iron alloy containing 5 atom % W. The levels were Coulomb excited with 2.5 MeV protons. The hyperfine energy in 182W is the same as that found by Mössbauer absorption. The variation of the field up to 300 °K is less than 6%. A comparison of g factors measured by the hyperfine field and the external field suggests the existence of a hyperfine anomaly.
Variation with Zenith Angle of the Integral Intensity of Muons near Sea Level
Authors: Flint R. W. , Hicks R. B. , Standil S.
Published: April 2011

The integral intensity of the cosmic ray muon flux (> 0.28 GeV/c) near sea level has been measured in the zenith angle range 75–90°. Very few other experimental measurements have been made in this range. The present results agree closely with the predictions of a current theoretical model except at very large zenith angles, where the measured intensities are somewhat higher than predicted.
Longitudinal Magnetoresistance in Gallium at 20.3 °K
Authors: Yahia J. , Lee C.
Published: April 2011

Measurements of magnetoresistance in single crystals of gallium at the temperature of liquid hydrogen are reported briefly and discussed.
Theory of Biexcitons
Authors: Božić-Popović M. , Lalović D. I. , Tošić B. S. , Žakula R. B.
Published: April 2011

The biexciton spectrum is analyzed taking into account the fact that the number of quasi-particles is not conserved. It is shown that in this case, apart from small corrections to the biexciton spectrum of the Heitler–London approximation, new biexciton levels appear. Besides, it is shown that, contrary to what is usually believed, in this case the approximate second quantization method does not give the correct zero-order spectrum of free excitons. The correct zero-order spectrum is also presented.
Flow Stress of Normal and Superconducting Indium
Authors: Hutchison T. S. , McBride S. L.
Published: April 2011

Measurements of the flow stress of normal and superconducting indium are presented. These are explained by a model which involves only the difference in thermal activation of the mobile dislocations in the two states and yields a flow stress difference which, for pure materials, can be expressed in terms of the thermal conductivity as (σN − σS) ~ ln (KN/KS). This relation is compared with experiment for pure indium and lead. The flow stress is also shown to provide a sensitive method of observing flux trapping in pure superconductors.
Dependence of the Diatomic Rotational Constant Bν on the Long-Range Internuclear Potential
Authors: Le Roy Robert J.
Published: April 2011

A simple expression is derived which explicitly relates the rotational constant Bν for vibrational levels near the dissociation limit D of a diatomic molecule, to the nature of the long-range interatomic potential. Assuming a long-range potential of the form V(R) = D – Cn/Rn, the expression Bν = Qn(νD – ν)[4/(n−2)] is obtained, where νD is the effective vibrational index at the dissociation limit, and Qn is a constant depending only on n, Cn, and the reduced mass. This result is slightly less accurate than an analogous recently developed relation for the vibrational level distribution near D. Its utility and accuracy are demonstrated by application to experimental data for the [Formula: see text] states of Cl2, Br2, and I2.
Spectre d'Emission de la Molecule PO : Transition C2Σ−–X2Πr et Nature de l'Etat C′
Authors: Coquart B. , Couet C. , Guenebaut H. , Larzillière M. , Ngo T. A.
Published: April 2011

The vibrational and rotational analyses of 27 red degraded subbands of PO in the region 1850–2350 Å, attributed to C–X2Πr system, are reported. The bands are photographed with a dispersion of 0.29 Å/mm. We observed three new vibrational levels of the C state. The identification of C as a 2Σ− state obliged us to reconsider the C–X2Πr transition. We concluded that C′ is a 2Δ state. A table of molecular constants for the C state is given.
Shock Relaxation in a Lightly Mass-Loaded Gas
Authors: Dimoff K. , Smy P. R. , Lacoste J.
Published: April 2011

For very low mass loading, the hydrodynamics of the gas can be regarded as completely uncoupled from effects of the particulate phase. Consequently, a simple analytic expression can be derived for the variation of dust density with time after the passage of a shock through such a gas–dust medium. Experimental confirmation, through the use of an electrostatic suspension system and a simple light attenuation technique, is sensitive enough to detect relaxation times of the order 10−5 s.
High Temperature Dielectric Constants of Rubidium Halides
Authors: Chandra Suresh , Prakash Jai
Published: April 2011

The high temperature dielectric constants of RbCl, RbBr, and RbI are measured at 24.6 GHz from room temperature to near melting point. A standing wave technique has been used. The dielectric constant of RbBr is observed to increase at a faster rate than that of RbCl and RbI.
Oscillation and Photoresponse of High-Resistivity n-GaAs Diodes
Authors: Torrens A. B. , Young L.
Published: April 2011

Diodes of lengths 0.17 mm and 1 mm with ohmic contacts were made from n-type, ~ 16 Ωm-resistivity GaAs. The diode resistance varies with temperature as exp (−Δ*/kT), with Δ** 412 meV. Above a threshold voltage of 50 to 80 V, depending on the diode, a small current oscillation occurs in the short diodes, which can be explained by the periodic propagation of small high-field domains at a velocity of the order of 1 m/s at room temperature. Several features of the transient response of the diodes to pulses are consistent with the occurrence of weak field-enhanced trapping effects which could account for the formation of the high-field domains.The long diodes exhibit a novel photoelectric effect: if a diode is illuminated and is subjected to a high-voltage step, the current assumes initially a value proportional to the voltage. Then, in about 1 μs, it decays by as much as 92% of its initial value. All the characteristics of this effect can be explained in terms of accumulation of minority carriers (holes) at the cathode of the diode (which is blocking for holes).
Quadratic Zeeman Effect of Donor Lines in Silicon and Germanium. I. Theory
Authors: Pajot B. , Merlet F. , Taravella G. , Arcas Ph.
Published: April 2011

Calculation of the quadratic Zeeman shift of donor lines of silicon and germanium has been undertaken in the effective mass theory framework. The energies are obtained by the perturbation method up to second order and a very small interaction between two sublevels m = 1 and m = −1 is found theoretically. The Zeeman patterns (phosphorus in silicon) for different configurations show crossing or noncrossing of the levels and sublevels, depending upon the chosen configuration. The results predict that for germanium, the p0 lines exhibit a splitting due to the anisotropic shift of these lines for some configurations. This theory can also be used for shallow impurities wherever the electron effective mass possesses ellipsoidal symmetry.
On the Ground State of B.C.C. 3He
Authors: Glyde H. R. , Khanna F. C.
Published: April 2011

The ground state properties of b.c.c. 3He are computed using both the localized single particle functions due to Nosanow and the correlated functions due to Koehler in conjunction with the T-matrix approximation of Glyde and Khanna. The trial functions and T matrix are computed iteratively much as suggested for the Brueckner–Hartree–Fock scheme for nuclear matter. The correlated ground state energy lies ~6 cal/mole below the single particle value and is in good agreement with the observed value of Pandorf and Edwards. The volume dependence, however, is poor suggesting that cubic terms such as incorporated in the improved theory of Goldman et al. are important in solid helium. When combined with lattice dynamic work, the present results suggest correlated functions provide a much better description of solid helium.
Anharmonic Phonons in B.C.C. 4He
Authors: Glyde H. R. , Khanna F. C.
Published: April 2011

A T-matrix approach is used to calculate lattice dynamics of b.c.c. 4He. The phonon frequency dispersion curves and phonon group widths are in reasonable agreement with the experimental results of Osgood et al.
Velocity Dependence of the Scattering Amplitudes in Resonant Collisions
Authors: Zaidi H. R.
Published: April 2011

The forward scattering amplitude for the two-body resonant collision is calculated as a function of the relative velocity. The interaction is assumed to be the long-range dipole–dipole, together with a short-range repulsive core. The quantum as well as semiclassical calculations are performed, and the validity of the existing calculations is discussed. Application of the results to the problem of resonance broadening is considered in detail.
Study of Low-Lying Levels in 37Ar
Authors: Taras P. , Turcotte A. , Vaillancourt R.
Published: April 2011

The properties of the first five excited levels in 37Ar were investigated via the 37Cl(p,n)37Ar reaction at Ep = 3.98, 4.17, 4.38, and 4.81 MeV and via the 34S(α,n)37Ar reaction at Eα = 8.00, 8.50, and 8.60 MeV. The following excitation energies were obtained: Ex = 1409.7 ± 0.4, 1611.5 ± 0.4, 2217.8 ± 0.8, 2491.4 ± 0.8, and 2797.0 ± 0.8 keV. These levels were found to decay almost entirely to the ground state. The angular distribution and the linear polarization of the decay gamma rays of these levels were measured. From these measurements definite spin–parity assignments as well as values of the mixing ratio of the ground state gamma-ray transitions were obtained. These are: Ex(Jπ, δ) = 1612 ([Formula: see text], +0.11 ± 0.02), 2218 ([Formula: see text], 0.0 ± 0.02), 2491 ([Formula: see text]), and 2797 ([Formula: see text], −0.16 ± 0.03 or +8.0 ± 1.5, the value of −0.16 being more probable). The measurements were also consistent with a spin of [Formula: see text] for the 1410 keV level. The results are compared with a recent shell-model calculation and are discussed in the context of the solar neutrino capture rate in 37Cl.
Perturbation Calculations for a Triangular Well Potential at Low Densities
Authors: Card Damon N. , Walkley John
Published: April 2011

The perturbation theory of Barker and Henderson is applied to a triangular well potential. Virial coefficients are evaluated using the local compressibility and macroscopic compressibility approximations as well as superposition theory. For a two-term inverse temperature expansion, the local compressibility approximation gives best agreement with exact virial coefficient data. The convergence of a five-term virial series is examined. At high temperatures good convergence to the (perturbation) equation of state is found.
The Transition from Free-Fall to Ambipolar Diffusion in the Mercury Afterglow Plasma
Authors: Roque C. R. , Gregory B. C.
Published: April 2011

A theoretical model describing the electron density and temperature decays of the mercury afterglow plasma is constructed. The plasma is assumed to be composed of six fluids: electrons, ions, ground state atoms, and metastable atoms. The transport equations based on the six-fluid model adequately describe the decay of electron density from the free-fall to the ambipolar regimes covering a pressure range of 5.8 × 10−4 to 5.8 × 10−2 Torr. It is shown that charge-exchange collisions dominate the density decay at high pressures and that collisions of the second kind strongly influence the temperature decay.
Theory of Quantum Diffusion in Solid Hydrogen and Deuterium. I. Calculation of the Jump Frequency
Authors: Oyarzun R. , Kranendonk J. Van
Published: April 2011

The jump frequencies of orthohydrogen impurities in solid parahydrogen due to intermolecular interchange and to resonant ortho–para conversion are calculated. The conversion process, due to the nuclear magnetic dipole–dipole interaction and reduced by the tumbling motion of the ortho molecules induced by the quadrupole–quadrupole interaction, is shown to be responsible for the observed quantum diffusion. The interchange process is completely negligible because of the rotational reduction effect. The quantum diffusion in solid deuterium is predicted to be more than two orders of magnitude slower than in hydrogen. The temperature dependence of the jump frequencies is very small.
Low-Lying Positive-Parity States in 101Tc
Authors: Cook W. B. , Johns M. W. , Geiger J. S. , Graham R. L.
Published: April 2011

Internal conversion measurement studies of the 14.6 min 101Mo β decay have led to the discovery of the following low-energy transitions in 101Tc: 6.281 ± 0.007 (75.4 ± 9%), 9.317 ± 0.010 (97 ± 1%), and 15.606 ± 0.015 keV (1.9 + 0.3%). From relative L-subshell intensities, the 6.281 and 9.317 keV transitions are found to be M1 with E2 admixtures of 0.010 ± 0.005% and 0.021 + 0.006% respectively; the weak 15.606 keV transition is E2 in character. These transitions establish excited states in 101Tc at 9.317 ± 0.010 and 15.601 ± 0.009 keV. The measured multipolarities together with decay scheme considerations lead to Jπ values of 9/2 +, 7/2 +, and 5/2 + for the ground state, the 9.317, and the 15.601 keV states respectively. Since these transitions were not observed in earlier studies of the β decay of 101Mo, quoted decay energies have been 15.6 keV too low. The measured K-conversion coefficient of the 80.926 keV transition shows that it is M1 with an E2 component of < 9%.
Photoneutron Cross Sections in 14N
Authors: Gellie R. W. , Lokan K. H. , Sherman N. K. , Johnson R. G. , Lodge J. I.
Published: April 2011

Photoneutron distributions from 14N have been obtained by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 15.5 to 29.5 MeV. A large part of the neutron yield is associated with the sequential decay of 14N to 12C, through well-defined intermediate states of 13C, at 7.55, 8.86, and 11.80 MeV, which are unstable against neutron emission. The (γ,n0) cross section for neutron emission to the ground state of 13N is found to agree very closely with the corresponding (γ,p0) cross section, implying a high degree of isospin purity for the giant dipole resonance of 14N. It is observed that the decay of the giant resonance proceeds freely through those odd-parity excited states of the A = 13 nuclei which are single hole states formed by the removal of a p-shell nucleon from the parent 14N.The integrated cross section for all neutron-producing interactions is found to be 88 ± 5 MeV mb.
Dicke Narrowing and Collision Broadening of the Depolarized Rayleigh and S0(l) Raman Line in the Hydrogen Isotopes and H2–He, H2–Ne Mixtures
Authors: Gupta B. K. , May A. D.
Published: April 2011

The profile of the depolarized Rayleigh line has been measured in H2, D2, HD, and in H2–He and H2–Ne mixtures. In addition the profile of the S0(1) rotational Raman line was determined in H2 and H2–He and H2–Ne mixtures. Observations were made at room temperature for 90° scattering and over a range of densities varying from about 1 to 100 amagat. Dicke narrowing and collision broadening of the profiles were observed in all cases. A reorientation cross section was calculated from the broadening coefficient of the depolarized Rayleigh line and compared with values obtained from NMR, the Scott effect, and the Senftleben–Beenakker effect. The agreement is satisfactory. From the Dicke narrowing a diffusion constant is extracted and compared with other values. The disagreement is attributed to the inadequacy of the theoretical expression for the contribution of the translational motion to the total profile and to the presence of correlation between the perturbation of the translational and internal molecular motion.
Sensitized Fluorescence in Vapors of Alkali Atoms. XIII. 62P1/2−62P3/2 Excitation Transfer in Rubidium, Induced in Collisions with Noble Gas Atoms
Authors: Siara I. , Hrycyshyn E. S. , Krause L.
Published: April 2011

The cross sections for excitation transfer between the 62P fine-structure substates in rubidium, induced in collisions with noble gas atoms, have been determined in a series of sensitized fluorescence experiments. Mixtures of rubidium vapor and noble gases at pressures varying in the range 0–5 Torr were irradiated with each component of the second 2P rubidium doublet in turn and the following cross sections for 2P mixing were obtained from measurements of sensitised-to-resonance fluorescent intensity ratios. Rb–He: Q12(2P1/2 → 2P3/2) = 29.3 Å2; Q21(2P1/2 ← 2P3/2) = 19.0 Å2. Rb–Ne: Q12 = 10.3 Å2; Q21 = 6.4 Å2. Rb–Ar: Q12 = 24.0 Å2; Q21 = 14.9 Å2. Rb–Kr: Q12 = 23.2 Å2; Q21 = 14.6 Å2. Rb–Xe: Q12 = 43.9 Å2; Q21 = 27.7 Å2 In their dependence on the magnitude of the fine-structure splitting, the values are consistent with previously determined cross sections for mixing in the first and third 2P doublets of alkali atoms.
Selection of a Single Pulse from a Mode-Locked TEA CO2 Laser
Authors: Rheault F. , Lachambre J. L. , Gilbert J. , Fortin R. , Blanchard M.
Published: April 2011

The isolation of a single pulse from a transversely excited atmospheric (TEA) CO2 laser, actively mode-locked by an acoustic loss modulator, is described. The single pulse selection has been achieved with the aid of a GaAs electrooptic shutter located either inside or outside the laser resonator. Pulses of 1 MW peak power and 2 ns duration have been recorded with instrument-limited precision. The availability of such pulses uncovers new possibilities for the investigation of laser–matter interactions at 10.6 μm.
Temperature Dependence of Bulk Viscosity in Liquid Argon
Authors: Cowan J. A. , Ball R. N.
Published: April 2011

Attenuation measurements have been made on liquid argon for temperatures between 90 and 150 °K and pressures between saturated vapor and 1000 p.s.i. Values of bulk viscosity were calculated and compared with theoretical results. For densities above 1.15 gcm−3 the PNM theory is in excellent agreement. However, below these values the theoretical results continue to decrease with density where the experimental results increase sharply. The values of the ratio of bulk to shear viscosity for saturated vapor pressure are found to be a linear function of (Tc–T)−3/2 from 90 to 140 °K.
Pseudopotential Calculation of Electrical Resistivity of Alkali Metals
Authors: Sharma P. K. , Srivastava S. K.
Published: April 2011

The electrical resistivity of alkali metals has been determined from various pseudopotential models for electron–ion scattering. Information about the solid structure factor is obtained using Krebs lattice dynamical model for the phonon dispersion relations. The results show reasonably satisfactory agreement with experiment.
Properties of the 612 keV Resonance in the 27Al(p,γ)28Si Reaction
Authors: Anyas-Weiss N. , Litherland A. E. , Smulders P. J. M.
Published: April 2011

Gamma rays from the resonance at Ep = 612 keV in the 27Al(p,γ)28Si reaction have been studied using a 40 cm3 Ge(Li) counter. Doppler shift measurements on the primary gamma ray show (85 ± 3)% of the expected full shift, indicating a lifetime of 13 ± 3 fs for the resonance level. A good parameterless fit to the 12angular correlation coefficients obtained by Heyligers suggests a spin of 5 for the resonance as an alternative to the previously considered values of 2, 3, and 4. A weak 2% decay from the 12 174 keV resonance level to the 3+ level at 8586 keV has been observed, and the E2/M1 mixing ratio for the decay from the 6276 keV, 3+ level to the 4617 keV, 4+ level has been obtained. A Q value for the 27Al(p,γ)28Si reaction of 11 584.1 ± 1.5 keV has been measured.
Exchange Splitting of Electron Spins in Copper-Based Kondo Alloys
Authors: Coleridge P. T. , Scott G. B. , Templeton I. M.
Published: April 2011

Modification of the Zeeman splitting of conduction-electron spins by an s–d exchange interaction has been studied in the de Haas – van Alphen effect at fields up to 50 kG and temperatures of order 1 K in very dilute copper-based alloys of Cr, Mn, Fe, and Co. In Cu(Cr) there is a linear relationship between an effective exchange energy and solute concentration, and the results indicate an antiferromagnetic interaction between conduction electrons and polarized impurity spins with very little Kondo screening. The effects of increasing field or decreasing temperature are consistent with a simple polarization of the impurity spins. The variation of the exchange energy from orbit to orbit is explained by the variation over the copper Fermi surface of the d-like part of the wave function. The occurrence of clean spin-splitting zeros in the Cu(Cr) system is believed to be a fortuitous result of a symmetrical positioning of the Friedel virtual bound states relative to the Fermi energy. In Cu(Mn) the exchange energy effects are similar to those in Cu(Cr) but involve also a differential scattering of the two spin components in the de Haas – van Alphen oscillations which results in spin-splitting minima rather than zeros. In Cu(Fe) and Cu(Co) differential scattering effects are also observed, but in Cu(Fe) the exchange energy is markedly reduced and in Cu(Co) it is almost completely eliminated by spin compensation of the impurity moment by conduction electrons.
A Note on the Spectrum of Se IV
Authors: Gautam M. S. , Joshi Y. N.
Published: April 2011

A 3 kJ θ-pinch discharge has been used in exciting metal vapor spectra. On the basis of the measurements in the region 2400 Å−420 Å, six new levels have been established in Se IV and 27 new lines have been classified.
Doppler-Shifted Cyclotron Resonance in Thin Metal Films
Authors: Turner R. , Cochran J. F.
Published: April 2011

According to Van Gelder the microwave absorption by a thin metal film in the presence of a static magnetic field normal to the film contains a series of peaks as the magnetic field is varied. In the present paper it is argued that these peaks correspond to Doppler-shifted cyclotron resonances of the carriers in the metal due to the quantization of electron momenta normal to the plane of the film. A simple quantum calculation is presented for the case of free electrons where the film is thin enough that to first order the microwave fields within are determined only by the boundary conditions and Maxwell's equations. The quantum expression is in good agreement with the absorption calculated using semiclassical arguments which can be readily extended to more complicated Fermi surfaces.
The Complete Spectrum of Collision-Induced Light Scattering in Compressed Argon
Authors: Irwin D. J. G. , May A. D.
Published: April 2011

A Michelson interferometer has been used to analyze the complete spectrum of the collision-induced depolarized light scattered by compressed Ar. Precise measurements of the width and integrated intensities are given. Some evidence for an intercollisional interference effect is found.
Spectroscopie par Source Laser. II. Etude Expérimentale de l'Elargissement des Raies de la Transition 00°1–(10°0, 02°0)I de CO2 Perturbé par N2. Application de la Théorie d'Anderson, Tsao et Curnutte au Calcul des Largeurs des Raies de CO2 Pur, et Perturbé par N2
Authors: Boulet C. , Arie E. , Bouanich J. P. , Lacome N.
Published: April 2011

The theory of Anderson, Tsao, and Curnutte has been applied to the calculation of self-broadened linewidths of CO2. The setting up of an experimental method using a laser source allowed us to measure systematically the broadening ability of nitrogen upon CO2 lines. The application of Anderson's theory has been extended to this type of interactions. In this study the limits of the determination method of the quadrupole moment have been shown by measuring the linewidths. In an other way, the influence of dispersion forces has been pointed out, if a semi-empirical potential is used.
Rotational Analysis of B–X2 System of 208PbF
Authors: Singh O. Nath , Singh I. S. , Singh O. N.
Published: April 2011

The rotational analysis of the three bands (1,0), (0,0), and (0,1) of the B–X2 system of PbF has been carried out. The bands have been excited in a transformer discharge and photographed in the second order of a 35 ft concave grating spectrograph. The analysis has shown that the bands arise from a 2Σ+–2Π3/2 transition. The rotational constants of the upper and lower states have been determined.
Vacuum Ultraviolet Excitation of H(2p) by Electron Impact on H2
Authors: McConkey J. W. , Donaldson F. G.
Published: April 2011

'Polarization-free' measurements are presented of the electron impact excitation of Lyman α by electron impact on H2 in the energy range 20–2000 eV. Cross sections are made absolute by normalizing to the data of Mumma and Zipf at 100 eV. A broad maximum in the function occurs around 60 eV, some 20 eV lower than was found by some previous workers. Reasons for this discrepancy are discussed. The high energy behavior of the cross section is analyzed in terms of the Bethe approximation and a value of 0.11 is obtained for the square of the dipole matrix element of the transitions involved.
Some Effects of Charge Polarization in Nuclear Fission
Authors: Ryce S. A. , Wyman R. R. , Stewart A. T.
Published: April 2011

It is shown that asymmetric mass division is to be expected in fission of a charged liquid drop if the charge is allowed to move freely between incipient fragments under the influence of the Coulomb field. For a nuclear fluid, forces which inhibit and which favor charge polarization are discussed. Parallels are drawn between the qualitative features of the polarizable liquid drop and fissioning nuclei.
Nonlinear Effects in Resonantly Driven Surface Waves on Fluids
Authors: Curzon F. L. , Ionides G. N.
Published: April 2011

The results presented in this paper show that fluid surface waves, resonantly driven by spatially nonuniform, time periodic electric fields, exhibit nonlinear effects when the wave amplitude ξ exceeds a significant fraction of the distance D between the driver electrode and the fluid surface. The phase difference between the surface wave and the driving force, as well as the dependence of wave amplitude on the electric stress are computed and compared with experimental results. For ξ/D exceeding ~0.7 (dependent on electrode geometry) the surface waves excited are unstable (also confirmed experimentally). The experiments are performed on surface waves on mercury contained in a cylindrical microwave resonator. Shifts in the microwave resonant frequency (caused by the surface waves) monitor the displacement of the fluid surface.
The Magnetic Properties and Mössbauer Spectra of Synthetic Samples of Fe3S4
Authors: Spender M. R. , Coey J. M. D. , Morrish A. H.
Published: April 2011

The magnetic properties of a number of samples of synthetic Fe3S4 have been studied using both static magnetization measurements and Mössbauer effect spectrometry. The distinction is made between the intrinsic properties of bulk Fe3S4 and observations resulting from superparamagnetic behavior and nonstoichiometry. Mössbauer spectra in applied fields show that the bulk material has a simple Néel ferrimagnetic spin arrangement. The magnetic moment at 4.2 °K is 2.2 ± 0.3 μB per formula unit and the ordering temperature is 606 ± 2 °K. Conductivity measurements indicate semimetallic behavior and two alternative band schemes are proposed to account for this feature and explain the magnetic moment.
Transient Light Emissions from a Laser Perturbed Plasma
Authors: Baldis H. A. , Nodwell R. A. , Meyer J.
Published: April 2011

The interaction between a 20 MW Q-switched ruby laser pulse and a partially ionized argon plasma has been studied experimentally. When the focused laser pulse is fired into the plasma, a transient emission from the plasma may be observed both in the continuum and line emission. From measurements of the absolute intensities of this transient radiation, estimates have been made of the population density of the excited atoms and of the electron densities. The Stark broadening of the Ar II lines has also been measured to obtain the electron density in the transient plasma and data obtained in this way are consistent with those obtained from the continuum radiation. During the time when the laser light is incident on the plasma the Ar II lines show a strong asymmetry which disappears quickly after the laser pulse has terminated. This asymmetry can be explained in terms of the electron density gradient present in the expanding perturbed plasma.
The Decay of 169Yb
Authors: Sen S. K. , Salie D. L. , Tomchuk E.
Published: April 2011

The decay of 169Yb was investigated using several Ge(Li) detectors of different sizes. The following gamma rays (energies in keV and intensities within brackets) were definitely identified with the 169Yb decay: 20.7 (0.66 ± 0.04), 63.1 (124 ± 5), 93.6 (7.2 ± 0.3), 109.8 (50 ± 2), 117.3 (0.08 ± 0.04), 118.2 (5.4 ± 0.2), 130.5 (34 ± 2), 156.7 (0.023 ± 0.004), 177.2(59 ± 3), 198.0 (100), 240.4 (0.33 ± 0.02), 261.0 (4.7 ± 0.2), and 307.7 (28 ± 1). The recently reported weak gamma-ray peaks at 515 (0.008 ± 0.002) and 625 (0.010 ± 0.002) were also observed and could not be ruled out as not belonging to 169Yb. The recently reported gamma-ray peaks at 140, 160, 207, 288, 295, 316, 320, 328, 355, 371, 379, 396, and 417 were detected and shown not to be from the decay of 169Yb while those at 218, 229, 285, 304, 335, 388, 411, and 425 were not observed and upper limits were placed on their intensities. The presence of very weak peaks at 515 and 625 establishes the formation of the 633 keV state of 169Tm following electron capture decay of 169Yb as reported by George. (This level has been previously observed only in Coulomb excitation of 169Tm.) The total internal conversion coefficient for the 20.7 keV transition was determined for the first time from the direct measurement of the gamma-ray intensity as 51 ± 10 corresponding to an M1 transition.
Dependence of Massive Superpropagators on the Strong and Weak Gravitational Coupling Constants
Authors: Leibbrandt G.
Published: April 2011

Numerical computations are presented for two massive superpropagators Sf g and S in terms of their respective coupling constants [Formula: see text] and [Formula: see text]∙S corresponds to the massive spin 2+f0 meson, while Sf g represents the superpropagator for a mixed tensor field consisting of Einstein's massless gravity field gμν and the strong gravity field fμν.It is found that both the general structure of Sf g and its asymptotic behavior in the ultraviolet limit, Sf g ~ x12 as [Formula: see text], remain basically unchanged for couplings in the range [Formula: see text]. The same conclusion holds for the massive superpropagator S in the coupling interval [Formula: see text]. All computations are carried out in Euclidean coordinate space.
Low-Temperature Thermomagnetic Effects in Graphite
Authors: Jay-Gerin J. P.
Published: April 2011

The low-temperature thermoelectric power (TEP) and the Nernst–Ettingshausen (NE) coefficient of graphite due to phonon drag are studied in the presence of a magnetic field H directed along the c axis and small enough for the quantum-mechanical character of the motion of the carriers to be negligible. Expressions for the TEP and the NE coefficient are obtained on the basis of the theory of Jay-Gerin and Maynard, in which the phonon-drag TEP of graphite in the absence of a magnetic field is linked with the Kohn screening anomaly. The results suggest a method by which information might be obtained about the strength of the electron– and hole–phonon coupling directly from experiment. A satisfactory agreement is found with the measurements of Takezawa, Tsuzuku, Ono, and Hishiyama and of Tamarin, Shalyt, and Volga.
The Formative Phase of a Low Pressure, High Voltage Z Pinch
Authors: Maclatchy C. S. , Barnard A. J.
Published: April 2011

The formative phase of a 40 kV Z pinch has been investigated for pressures from 10 to 80 mTorr in H2. The energy spectrum of the electrons on the axis of the vessel, the spatial distribution of the current at the face of the anode, and the total discharge current were monitored. At the initiation of the discharge, a current of electrons with energies in excess of 20 keV is observed on the axis. This observation is in contrast to the normally accepted mode of ionization in which ionization initiates at the wall. The current is observed to switch from the axial region to the wall where it forms a current layer which collapses in accordance with the snow-plough model. The exact nature of the switching mechanism is not understood. The formative phase of the pinch typically takes a few hundred nanoseconds. The observations indicate that the detailed process of current sheet collapse may be affected by the formative phase.
The Isospin Coupling Potential Below the Quasi-Elastic (p,n) Thresholds
Authors: Ramavataram S.
Published: April 2011

A form for the isospin coupling potential is derived using a particle–hole model and a coupled-channel treatment of the isobaric analogue resonance. It is well suited for numerical investigations. Comparison with the phenomenological approach shows that the present treatment provides interesting insights into the real and imaginary components of this potential.
The Optical Properties of Amorphous ZnTe and CdTe
Authors: Brown H. M. , Brodie D. E.
Published: April 2011

Amorphous films of ZnTe and CdTe have been prepared by vacuum deposition of the compounds onto −150 °C sapphire substrates. Structural studies reported earlier by Brown and Brodie indicate that the crystallite size in the amorphous phase is less than 25 Å, and that the basic crystalline tetrahedral units of the zinc-blende structure are retained in the amorphous phase.Both the reflectivity and absorption spectra display only one broad maximum associated with transitions involving energy states near the center of the Brillouin zone and in the [Formula: see text] directions, the bond directions between neighboring atoms in the tetrahedra. These bonds are not disturbed by the lack of long range order. The strong E2 transition observed with polycrystalline samples is absent in the amorphous films. This transition is associated with energy states near the X point in the zone and the nature of these states is changed. The X point is in the [Formula: see text] direction at the zone boundary and the bonds associated with this direction connect neighboring tetrahedra. The fundamental band edge is less affected by disorder. It is as steep as the polycrystalline band edge but shifted to lower energy. The edge temperature dependence is the same as that of the crystal but transitions just above the band edge are indirect in contrast to the crystalline case where they are k conserving.
Excitation Curves for the Reactions of Fast Neutrons with Zinc
Authors: Santry D. C. , Butler J. P.
Published: April 2011

The activation method was used to measure cross section values from threshold energies up to 20 MeV for the reactions 64Zn(n,p)64Cu, 68Zn(n,α)65Ni, and 70Zn(n,2n)69Znm. The neutron flux at energies below 5.3 MeV was determined with a calibrated neutron long counter while at higher energies measurements were made relative to the known cross section for the 32S(n,p)32P reaction. Effective cross sections for a fission-neutron spectrum calculated from measured excitation curves are 42.3 ± 2.1 mb for the (n,p) reaction, 0.035 ± 0.003 mb for the (n,α) reaction, and 0.45 ± 0.04 mb for the (n,2n) reaction. Factors influencing precise measurements of fast-neutron cross sections are discussed in detail.
On the Aspect Sensitivity of Radio Aurora
Authors: McDiarmid D. R.
Published: April 2011

Previous measurements of the aspect sensitivity of radio aurora at VHF have yielded two distinctly different values, namely, 10 dB/deg and 1 to 2 dB/deg. In this paper, a previously discussed event is re-analyzed in greater detail in an attempt to resolve this apparent anomaly. The results of this analysis, which takes account of the effects of a number of measurement errors and uncertainties, lead to the conclusion that the aspect sensitivity of the event could not have been greater than [Formula: see text] in the aspect angle interval of approximately 4.5° to 19.5°. The most likely value is between 1.3 and 1.5 dB/deg. It is suggested that the two observed aspect sensitivity curves correspond to different radio aurora producing mechanisms.
Steady Transverse Plane Magnetogasdynamic Flows
Authors: Chandna O. P.
Published: April 2011

A compatibility equation is obtained for steady plane transverse MHD flows and, as an example, solutions are obtained for radial flows. The geometric implication, when the compatibility equation does not hold, is also determined.
Pressure Dependence of the Energy Gap Anisotropy in Aluminum
Authors: Leavens C. R. , Carbotte J. P.
Published: April 2011

We have calculated the superconducting energy gap for a large number of points on the irreducible (1/48)th of the Fermi surface of pure single-crystal aluminum both at zero and finite pressure. It is found that the energy gap anisotropy in aluminum increases with increasing pressure.
The 154Eu → 154Gd Decay
Authors: Nagpal T. S. , Gaucher R. E.
Published: April 2011

The γ and electron conversion spectra in the 154Eu → 154Gd decay have been observed using solid state detectors. The present results have improved the available conversion data on this decay.
Vibrational Energy Transfer Probabilities due to Coulomb Interaction
Authors: Tam W. G.
Published: April 2011

The Sharma and Brau theory developed for the near-resonance vibrational energy transfer processes due to the Coulomb interaction between colliding molecules is shown to be valid also for processes which are far away from resonance. A modified Sharma and Brau theory valid for arbitrary energy discrepancy is described. For off-resonance vibrational energy transfer the head-on collisions are shown to play a dominant role.
Atmospheric Pressure CO2 Pulsed Laser with Semiconducting Plastic Electrodes
Authors: Bélanger P. A. , Tremblay R. , Boivin J. , Otis G.
Published: April 2011

The characteristics of a TEA laser with a new type of electrode have been investigated in a preliminary study. The method used consisted of replacing the discrete discharge elements by smooth semiconducting plastic electrodes which allow good control of the discharge, greater injection of CO2, and greater excitation cross section than the discrete discharge elements, and produce a plasma with good optical properties.
Some Extensions of the Schematic Model for Core Polarization of the Nuclear Effective Interaction
Authors: Sprung Donald W. L. , Jopko A. M.
Published: April 2011

A number of higher order core polarization processes recently considered by Kirson are here treated in the case of the soluble schematic model. We confirm the conclusion of Kirson that the sum of all the processes considered gives a very small contribution to the shell model effective interaction. In particular, the anomalously large results found in the RPA are disposed of.
Critical Currents in NbSe2: Evidence for Surface Pinning
Authors: Kopp J. , Huntley D. J. , Frindt R. F.
Published: April 2011

The variation of critical current density for flux flow with thickness has been measured for crystals of NbSe2 between 10−6 and 0.03 cm thick. The dominant behavior is that [Formula: see text] (thickness)−1 and this is interpreted as evidence for surface pinning predominating over bulk pinning of the flux lines.
Electronic Structure of Disordered Binary Alloys: α-Brass
Authors: Das M. P. , Joshi S. K.
Published: April 2011

We have given a brief review of the existing approaches towards the study of the electronic structure of disordered binary alloys and have discussed Soven's single-site coherent potential approximation. An angular momentum representation of the Green function with Slater's δ-function-type potential is used to calculate the spectral density of electronic states of the disordered alloy, α-brass. We have compared the results of our calculation with available optical and photoemission data.
Theory of Intercollisional Interference Effects. III. Collision-Induced Light Scattering
Authors: Lewis J. Courtenay , Kranendonk J. Van
Published: April 2011

The kinetic theory of intercollisional interference effects in optical spectra of gases developed in two previous papers is extended to the collision-induced light scattering from monatomic gases. The quadratic dependence of the incremental polarizability on the direction cosines of the intermolecular axis, compared to the linear dependence for the induced dipole moment, makes the effect quite different for light scattering and absorption. For a hard-sphere model an intercollisional peak, rather than a dip, of a relative height of 25% and a width proportional to the density is predicted to appear on top of the intracollisional light scattering spectrum.