bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystal Dynamics of Platinum by Inelastic Neutron Scattering
Authors: Dutton D. H. , Brockhouse B. N. , Miiller A. P.
Published: April 2011

The dispersion relations in platinum have been measured at 90 °K by the inelastic scattering of thermal neutrons. Born–von Kármán models of the force system have been calculated by fitting to the dispersion curves. Fourth-neighbor forces, with weaker interactions probably extending to at least sixth neighbors, are required to fit the data. A frequency distribution has been calculated from the force constants of the most realistic model.Some measurements are also reported of frequencies at a temperature of 473 °K. The mean frequency shift from 90 to 473 °K was found to be −2.0%.In the [0ζζ]T1 branch, anomalous behavior, similar to that observed in palladium, has been studied at temperatures of 90, 296, and 473 °K. As in Pd, the anomaly in Pt is markedly broadened and weakened with increasing temperature. The phonon wave vectors corresponding to possible Kohn transitions in the (001) plane have been determined by machine calculation, using Fermi surfaces given in the literature. These results strongly suggest that the anomaly along the T1 branch arises largely from transitions across the "heavy" hole Fermi sheet formed from the fifth-band electrons. A comparison is made with similar results for palladium and nickel.
Force Between Metal Plates Arising from the Contact Potential
Authors: Guptill E. W. , Calkin M. G. , Jericho M. H.
Published: April 2011

We demonstrate experimentally that potential gradients associated with contact potential differences exert forces on charges, in agreement with theory.
Ion Density Measurements in the Wake of a Hypersonic Sphere
Authors: Sévigny L. , Heckman D. , Caron P.
Published: April 2011

A report is presented of the results of a major research effort undertaken to determine experimentally, through the use of cylindrical electrostatic probes and existing probe theory, the levels of ion density in the turbulent wakes behind 2.7 in. diameter spheres flown at 14 500 ft/s in a ballistic range filled with nitrogen at 7.6 Torr and at 20 Torr. Measurements of the ion current distribution have been made by means of a transverse survey array of cylindrical electrostatic ion probes. Three static theories and three kinetic theories have been applied to the mean current data of the probes, and experimentally measured temperature and velocity distribution data for sphere wakes was used to construct radial distributions of ion density estimates for each theory. These radial distributions have been fitted with gaussian curves by the method of least mean squares. Two parameters of the ion density distributions are determined: the ion density on the axis of the wake and the ion density radius of the wake. These results have been compared with electron density levels in the wake deduced from microwave interferometer measurements and Langmuir probe instrumentation.
Gain Correlation with Sidelight and Plasma Impedance Properties of a CO2 Laser Discharge
Authors: Crane R. A. , Waksberg A. L.
Published: April 2011

The gain at 10.6 μ, in a CO2 laser gas mixture, is correlated as a function of discharge current with the induced changes in the plasma impedance and spontaneous emission at 2.4 μ and 3576 Å. The results reveal the possible use of these properties for laser stabilization and 10.6 μ detector applications.
Radiation from an Axial Slot Antenna Coated with a Homogeneous Material
Authors: Shafai L.
Published: April 2011

Radiation from a slotted-cylinder antenna coated with a homogeneous material is investigated. It is found that for some values of the coating thickness certain modes may resonate, which greatly enhance the radiated power and affect the shape of the radiation patterns.
Magnetic Structure of Manganese Pyrophosphate and Copper Pyrophosphate
Authors: Stiles J. A. R. , Stager C. V.
Published: April 2011

The magnetic structures of antiferromagnetic manganese pyrophosphate and copper pyrophosphate have been determined by single crystal neutron diffraction techniques. There have been two previous determinations of the structure of manganese pyrophosphate. The discrepancy between these results is explained by postulating a crystallographic phase transition.
A Study of Thermal Neutron Capture in Chlorine
Authors: Ishaq A. F. M. , Kennett T. J.
Published: April 2011

The gamma-ray spectrum after thermal neutron capture has been studied using a Ge(Li) pair spectrometer. Out of 140 transitions observed above 1.95 MeV, 3 have been tentatively assigned to 38Cl and the rest to 36Cl. An improved decay scheme is proposed for 36Cl which involves 43 levels. The Q value for the 35Cl(n,γ)36Cl reaction is estimated to be 8579.1 ± 0.5 keV and the multiplicity of the reaction found to be 2.5. A tentative estimate of the Q value for the 37Cl(n,γ)38Cl reaction yielded a result of 6107.4 ± 0.8 keV. The mean reduced widths for primary dipole transitions have been calculated and compared with theoretical estimates.
Cumulative Yields of the Heavy Fragments in the Fast Neutron Fission of 238U
Authors: Mathews C. K. , Tomlinson R. H.
Published: April 2011

Isotopic abundances of the elements xenon, cesium, barium, cerium, neodymium, and samarium formed in the fast (fission spectrum) neutron fission of 238U have been measured using the mass spectrometric method. These ratios were normalized with respect to each other through isobaric nuclides and isotope dilution to obtain the relative yields of isobaric chains in the heavy mass region. By normalizing the heavy mass yields to 100%, the absolute fission yields of 20 chains in the 130–154 mass range were determined.
Magnetic Levitation: Linear Synchronous Motor Efficiency
Authors: Atherton David L. , Love L. E. G. , Prentiss P. O.
Published: April 2011

Large gap linear synchronous motors suitable for magnetically levitated high speed guided ground transport are considered. It is shown that if a is the gap (suspension height) propulsion magnets have an optimum length of 1.5a and induce an almost sinusoidal wave form in the guideway coils. The efficiency is then η = 1/[1 + PR/E2, cos2 θ] where E is the induced voltage, P the power, R guideway resistance, and cos θ the ratio of average to peak power. A design example shows that high efficiency is possible even at a suspension height of 30 cm.
Proton States in 155Tb, 157Tb, 159Tb, and 161Tb
Authors: Tippett J. C. , Burke D. G.
Published: April 2011

Proton states in the odd terbium isotopes 155Tb, 157Tb, 159Tb, and 161Tb have been studied using (3He,d) and (α,t) reactions. The beams of 24 MeV 3He and 25 MeV alpha particles were produced by the McMaster University model FN tandem Van de Graaff accelerator. The reaction products were analyzed with an Enge split-pole magnetic spectrograph and detected with photographic emulsions. The ratios of cross sections in the (3He,d) and (α,t) reactions were used as an indication of the/values for the proton transfers, and the spectroscopic factors were extracted using DWBA calculations. The results of the present work confirm the assignments of the 3/2+ [411] and 5/2+[413] Nilsson orbitals in all four isotopes. The I = 11/2 states of the 5/2−[532] and 7/2−[523] orbitals were identified in 161Tb and 159Tb and their assignments confirmed in 157Tb and 155Tb. It was necessary to invoke appreciable Coriolis mixing between these two orbitals in order to describe the observed rotational level spacings and the spectroscopic strengths. The assignments of the 7/2+[404] orbital were confirmed in 155Tb and 157Tb and this orbital was identified in 159Tb and 161Tb. Previous assignments of the 1/2+ [411] particle state with vibrational admixtures were confirmed in 157Tb and 159Tb and the state was identified in 161Tb. The present results support earlier evidence for the existence of a second fragment of the 1/2+[411] orbital in 159Tb and suggest the presence of a similar state in 157Tb. In each of the isotopes the 5/2+[402] orbital was assigned and a tentative assignment for the 1/2−[541] orbital was proposed.
Absorption of Light at Oblique Incidence on a Plasma Layer
Authors: Burnett N. H.
Published: April 2011

Two effects are examined which may lead to enhanced absorption of light by sharply bounded plasma layers at oblique incidence. The first is a resonance absorption caused by interference of light reflected from the front and rear boundaries of the layer. The second is the linear coupling of the incident transverse wave into longitudinal plasma waves. It is thought that these effects may be useful in obtaining increased efficiency in laser heating of plasmas.
Anisotropy in the Superconducting Energy Gap of NbSe2
Authors: Clayman B. P.
Published: April 2011

The superconducting energy gap in single crystals of NbSe2, a layer structure, has been determined to be anisotropic by measuring the far-infrared transmission spectrum. The gap for electron velocities in the layers is [Formula: see text] and for velocities perpendicular to the layers is [Formula: see text]. These results are compared with recent tunneling experiments.
Study of the Conditions Set by Unitarity and Time-Reversal Invariance in the ρ–ω Mixing with the Three-Body Mixing Formalism
Authors: Gien T. T.
Published: April 2011

Using the three-body interference formalisms recently developed by us, we study the conditions imposed by time-reversal invariance and unitarity on the relative phase and strength of the ρ–ω mixing in the presence of vector meson [Formula: see text]. It is found that the effect of vector meson [Formula: see text] on these conditions when they are compared to those obtained with the usual two-body interference formalisms is very small. Even if the width of [Formula: see text] was ten times larger than the actual one, still this effect would be negligible. Thus, this detailed analysis confirms again the possibility of neglecting the effect of [Formula: see text] in the ρ–ω mixing problem. All the conclusions reached by us in this study are based purely on the experimental data alone and thereby, independent of the detailed dynamical assumptions on the decays of ρ, ω, and [Formula: see text]. We also wish to point out that an upper bound for the ρ–ω mixing strength in the 2π decay mode can be obtained from the knowledge of the masses and partial decay rates of channels other than 2π of ρ and ω.
Evidence for the 11/2− Member of the K = 1/2− Band in 19F
Authors: Rogers D. W. O. , Dixon W. R. , Storey R. S.
Published: April 2011

A new resonance at 3993 ± 2 keV has been found in the 15N(α,γ)19F reaction corresponding to a level at 7165.7 ± 1.0 keV in 19F which decays primarily to the 9/2− level at 4032 keV (94 ± 2%) and weakly to the 7/2− level at 3999 keV (6 ± 2%). The decay scheme, angular distributions, and radiative width (ωγ = 1.15 ± 0.23 eV) together with some crude estimates of α widths imply Jπ is most likely 11/2− The lifetime of the 9/2− level was measured using the DSAM to be τ = 87 ± 16 fs. The decay properties of the 11/2− and 9/2− levels agree well with the predictions for the 11/2− and 9/2− members of the K = 1/2− band in 19F.
Antisymmetric Bosons in Nuclear Structure
Authors: Banville M. , Simard P. A.
Published: April 2011

The concept of an ideal space of bosons and ideal particles is applied directly to systems of ordinary particles with a transcription of the particle into that ideal space that preserves both the Pauli principle and the transformation properties of the one- and two-body operators. We treat systems up to four particles.
Excitations in Magnetic Systems with Various Crystal-Field Level Schemes
Authors: Hsieh Y. Y.
Published: April 2011

The Hamiltonian constructed in a previous work in pseudo-spin space to explain the crystal-field effects in certain magnetic systems with various crystal-field level schemes has been studied in the random phase approximation of the double-time Green function method. By using the molecular field results obtained before as a second approximation, we obtain the low-lying collective excitation spectra at zero and finite temperatures. As an application, we have extended our calculations to look at the dispersion curves of the d.h.c.p. praseodymium single crystal. Comparison with the experimental measurements is discussed. Suggestions on further studies and possible improvements of the present calculations are also provided.
Second-Order Raman Spectra and Phonon Dispersion in GaP
Authors: Hoff R. M. , Irwin J. C.
Published: April 2011

The second-order Raman spectrum of GaP has been investigated experimentally. The experiments were performed on oriented single crystals at both 300 and 77 °K. A critical point analysis of the data has been carried out with the aid of the polarization selection rules. The resulting frequencies are also consistent with a theoretical model which in turn is used to calculate the phonon dispersion throughout the Brillouin zone. The one- and two-phonon density of states and the specific heat have also been calculated and compared to our spectra and available specific heat data. The calculated quantities have also been compared to similar quantities obtained from neutron scattering experiments. This comparison provides information on the accuracy and reliability of phonon dispersion curves obtained from Raman scattering experiments.
Nuclear Magnetic Resonance in Antiferromagnetic Cu2P2O7
Authors: Stiles J. A. R. , Stager C. V.
Published: April 2011

The 31P nuclear magnetic resonance has been studied for the antiferromagnetic state of Cu2P2O7. The external field was smaller but in many cases comparable to the spin flop field. It was necessary to correct for the perturbation of the spin system by the applied magnetic field. The data are compared with the spin configuration determined by neutron diffraction, the transferred hyperfine interaction measured in the paramagnetic state, and the magnitude of distortions from a higher symmetry phase.
ESR Spectrum of Fe3+ in Topaz. III. ENDOR of 19F
Authors: Barry W. R. , Holuj F.
Published: April 2011

An ENDOR of Fe3+ impurity in topaz (Al2SiO4F2) yielded the hyperfine structure tensors of the two 19F− ions adjoining the Al3+/Fe3+ site. The principal axes are very well correlated with the site symmetry and the bond directions. The percentage experimental spin densities of the two fluorines are[Formula: see text]
Single Particle Green's Function in the Electron–Plasmon Approximation
Authors: Bergersen B. , Kus F. W. , Blomberg C.
Published: April 2011

A discussion of how to carry out a direct perturbation expansion for the one-electron Green's function is given using an electron–plasmon model for the conduction electron correlations. A crucial feature of the method is the consistent extraction of energy shifts. Numerical results for the spectral function and the density of states are given in lowest order and the generalization to higher order is discussed. The present work differs from previous ones in that the method used cannot give rise to "plasmaron"-like excitations. Other singular features also come in differently.
Fast Neutron Scattering at 180° from Pb and Sn
Authors: Gupta M. C. , Tripard G. E.
Published: April 2011

A measurement of the differential scattering of 3.65 MeV neutrons from the D(d,n)3He reaction at the angles 10° and 180° by Pb and Sn was made. The results at 180° were anomalously high compared with optical model predictions. An experimental arrangement using the associated particle technique and large thin film (CD2)x targets is described which has made measurements of the differential scattering of neutrons at the extreme backward angles (~180°) possible.
Dielectric Relaxation in Symmetric-Top Molecules at Radio Frequencies
Authors: Clark Robert , Bloom Myer
Published: April 2011

Dielectric relaxation has been observed in gaseous methyl fluoride (CH3F) and fluoroform (CHF3). The dispersion χ′ was measured at 30 MHz as a function of density at constant temperature (309 °K) over a density range from 10−3 to 1.0 amagat. Molecular collisions have been treated by assuming an exponentially decaying dipole-moment correlation function. The collision diameters obtained have been compared with those obtained from microwave nonresonant absorption. The relationship between information from dielectric relaxation measurements and nuclear spin–lattice relaxation measurements is discussed briefly.
Studies in Molecular Dynamics by Collision-Induced Infrared Absorption in H2–Rare Gas Mixtures. I. Profile Analysis and the Intercollisional Interference Effect
Authors: Mactaggart J. W. , Welsh H. L.
Published: April 2011

The pressure-induced infrared fundamental band of hydrogen in H2–rare gas mixtures was recorded over a wide range of temperatures (77–300 K) and densities (5–1200 amagat) using pressures up to 2000 atm. By assuming appropriate line shapes for overlap- and quadrupole-induced transitions the band profiles could be computer analyzed in terms of essentially three parameters, δd, δc, and δq. The value of δd, the half-width of overlap-induced transitions, was found to be density independent, thus indicating the very short range of this induction process. The half-width, δc, of the intercollisional interference dip for overlap-induced transitions increases with the density, ρ, according to the equation, [Formula: see text]. The collision cross section for overlap induction, calculated from the linear coefficient a, is ~10% greater than the Lennard–Jones σ12. The relation of δc to the diffusion coefficient D12 of H2 molecules in the rare gas is discussed. Data on the half-width δq of quadrupole-induced transitions will be analyzed in paper II of this series.
Relationship of Quadrupole–Quadrupole Interactions to SU(3) Invariance and Rotational Bands for a Four-Nucleon System
Authors: Turner R. James , Trainor L. E. H.
Published: April 2011

The nature of the quadrupole–quadrupole interaction in a simple harmonic oscillation model is analyzed in some detail, with particular reference to group symmetries, SU(3) invariance, and the existence of rotational or quasi-rotational bands. Basis states having good space symmetry and SU(3) and R(3) quantum numbers are constructed using the methods of Moshinsky and collaborators. The multi-shell calculations are limited for reasons of tractability to the 4-nucleon system. The results show that the SU(3) model is highly idealized and that the appearance of SU(3) symmetry and rotational bands is strongly influenced by major shell mixing, changes in the radial dependence of the force, and even to some extent by inclusion of self-energy terms in the quadrupole–quadrupole interaction.
The 149,151Sm(p,t)147,149Sm Reactions
Authors: Gadsby R. D. , Burke D. G. , Waddington J. C.
Published: April 2011

Two-neutron pickup reactions have been performed on targets of 149Sm and radioactive 151Sm using 18 MeV protons. The outgoing tritons from the 151Sm target were analyzed with a magnetic spectrograph at 16 angles between 6 and 80°. Unlike the two-neutron transfer data on neighboring even–even targets, the angular distributions indicated l = 0 transitions to many levels in the final nucleus. Partial angular distributions for the 149Sm(p,t)147Sm reaction were obtained, but showed only one strong l = 0 transition populating the 147Sm ground state. In addition, spectra from the 152Sm(p,t) reaction were measured at several angles in order to provide normalization to previous results.
Electromagnetic Induction in Conductive Shells
Authors: Wait James R.
Published: April 2011

The shielding characteristics of thin conductive shells are considered. Both elliptical and spheroidal shapes are treated using a thin-sheet boundary condition. It is shown that the form of the solutions is relatively simple if the angular variation of the shell thickness is taken to vary in a prescribed fashion. In such cases, the internal field is reduced by a factor (1 + iωτ)−1 relative to the external primary field where ω is the angular frequency and τ is a response factor that depends on the shell dimensions. The well-known results for cylindrical and spherical shells are obtained as special cases.
Observation of a New Effect on the Fluorescence of Molecular Iodine Excited by Ionized Argon or Krypton Lasers
Authors: Broyer M. , Dalby F. W. , Vigué J. , Lehmann J. C.
Published: April 2011

Iodine vapor excited by certain lines of ionized argon or krypton lasers emits an intense fluorescence. We have observed large variations in light intensity which can neither be interpreted as a Hanle effect due to the applied fields, nor to predissociation.
Electrode Ablation in an Electromagnetic Shock Tube
Authors: Sharah A. , Cormack G. D.
Published: April 2011

Electrode ablation in a rail type of electromagnetic shock tube has been studied. Cathode ablation was found to be present over a wide range of experimental parameters whereas anode ablation was found to be immeasurably small. The parameters varied included the drive current, gas pressure, and the electrode material. Observations of current sheet velocity were interpreted as evaporation of cathode material from cathode spots. The ablation series determined from velocity data for the metals tested was: mild steel, Zn, Cu, Mo, in order of decreasing amount of ablation.
Etude Numérique de la Section Efficace de Diffusion d'un Faisceau Laser par un Plasma en Champ Magnétique. Application à la Détermination Expérimentale de la Direction du Champ Magnétique de Confinement
Authors: Meyer R. L. , Leclert G. , Felden M.
Published: April 2011

We study the influence of the magnetic field intensity and direction with respect to the wave vector on the scattering cross-section resonances. We deduce the best experimental conditions for studying these resonances. It is shown that the spectrum modulation of the scattered wave can be used to measure, in some configurations, the confining magnetic field direction.
Emission Spectrum of the PO Molecule. Part IV. Spectrum in the Region 7000–12 000 Å
Authors: Verma R. D. , Jois S. S.
Published: April 2011

A new transition, A2Σ+–B2Σ+, of the PO molecule has been observed in the region 7000–12 000 Å. From the rotational analysis of the bands numerous perturbations have been observed in the ν = 0–5 levels of the A2Σ+ state. These perturbations have been shown successfully to be partly due to the B′2Π1 state and partly due to a new 4Σ− state. A shift has been detected in the A2Σ+, ν = 3, 4, and 5 levels, which has been attributed to a vibrational perturbation produced by the F2Σ+ state. A new G2Σ+–A2Σ+ transition also is reported.
Recrystallization Effects in Amorphous Tl2Te Films
Authors: Harris J. J. , Brodie D. E. , Eastman P. C.
Published: April 2011

Measurements on films of amorphous Tl2Te grown on liquid nitrogen-cooled substrates have shown that the conduction process at low temperatures is thermally activated, with energies of 0.21 and 0.26 eV. In the temperature range 261 to 289 °K the films underwent a rapid recrystallization, accompanied by an increase of about 3 orders of magnitude in conductivity.
Intensities and the Fano Line Shape in the Infrared Spectrum of HD
Authors: McKellar A. R. W.
Published: April 2011

The spectrum of gaseous HD at a temperature of 77 K and densities from 1 to 60 amagat has been studied in the regions of the fundamental and first overtone bands. The 1–0 band consists of two components: (1) a collision-induced part, made up of broad Q and S transitions arising from collisions between molecules, and (2) a dipole-allowed part, made up of much sharper P and R transitions due to free molecules. The collision-induced 2–0 band was too weak to be observed in these experiments, but the first overtone R(0) transition was studied. The collision-induced fundamental band shows the expected similarity to the previously observed spectra of H2 and D2. A pronounced asymmetry in the fundamental band P and R transitions may be ascribed to a resonant interference with the underlying collision-induced continuum. Measurements of the intensities of the appropriate R(0) lines yield the following transition dipole moments: (0.49 ± 0.02) × 10−4 D for the fundamental, and (0.21 ± 0.02) × 10−4 D for the first overtone band.
Anisotropic Intermolecular Interactions in the Rotation–Vibration Raman Spectrum of Solid Hydrogen
Authors: Prior William R. C. , Allin Elizabeth J.
Published: April 2011

The rotation–vibration Raman spectra of solid mixtures of ortho- and para-hydrogen have been studied over a wide concentration range. If the proportion of J = 1 molecules is below ~ 70% the samples have an h.c.p. structure at all attainable temperatures; for higher concentrations a change to an f.c.c. structure occurs at ~ 1.3 K. In the h.c.p. phase the S1 lines show no structure, and the principal effect of anisotropic interactions is to decrease the degree of localization, and thus the energy, of the bound state into which the Raman transition takes place. This decrease is negligible for the S1(1) transition in hydrogen and at all concentrations the frequency is approximately that calculated on the basis of isotropic interactions only, so that in this phase crystalline field effects must be small.In the f.c.c. phase both lines are split into a number of components, and the structure of the S1(1) transition in hydrogen is well represented by the splitting of a bound J = 3 state by a Y20 crystalline field due to quadrupole–quadrupole interactions between nearest neighbors. In deuterium other effects of anisotropic interactions are also important.The observation of double transitions shows a dependence of the anisotropy of the polarizability of the solid on the molecular interactions.
Possibilités d'un Effet Laser dans les Polyacènes
Authors: Rulliere C. , Denariez-Roberge M. M.
Published: April 2011

Theoretical gain calculation in some polyacene allows us to account for several factors (new kinetics constants, excited singlet and triplet absorption, photochemical reactions). We have studied the influence of these factors on the gain and so a possible laser effect is discussed.
Coherence Transfer between the 2P1/2 and 2P3/2 States in Potassium, Induced in Collisions with Noble Gas Atoms and with Molecules
Authors: Niewitecka B. , Krause L.
Published: April 2011

The transfer of coherence accompanying 42P1/2 → 42P3/2 transfer of excitation induced in collisions between 42P1/2 potassium atoms and noble gas atoms as well as some simple molecules, was studied in a series of sensitized fluorescence experiments. Mixtures of potassium vapor at 6 × 10−7 Torr with the various buffer gases were irradiated with circularly polarized D1(σ+) light and the relative intensities of the σ+ and σ− fractions of both the D1 and D2 fluorescent components were determined in relation to the pressures of the buffer gases. The experiments yielded the following cross sections for coherence transfer: K–He:1.7 Å2; K–Ne :0.8 Å2; K–Ar < 0.5 Å2; K–H2 :3.5 Å2; K–CH4 :7.0 Å2; K–CD4:7.7 Å2.
Mass of the Graviton
Authors: Hare M. G.
Published: April 2011

The graviton is assumed to have a mass and it is allowed to decay into two photons. From the transition probability for this decay an illustrative restriction is placed upon the graviton mass. Restrictions are also made on the mass with regards to the speed of propagation of gravitational radiation and to the range of gravitational forces.
A Study of Levels in 149Nd using the (d, t) and (3He, α) Reactions
Authors: Burke D. G. , Waddington J. C. , Nelson D. E. , Buckley J.
Published: April 2011

Triton spectra from the 150Nd(d, t)149Nd reaction have been measured at 15 angles using beams of 12 MeV deuterons. The 150Nd(3He, α)149Nd reaction was studied at four angles with 24 MeV 3He beams. In all cases the reaction products were analyzed with an Enge-type magnetic spectrograph and detected with photographic emulsions. The peak widths (FWHM) were approximately 8 keV for the (d, t) studies and 25 keV for the (3He, α) spectra. It is now evident that the highest energy triton group ascribed to the 150Nd(d, t)149Nd reaction in previous works does not correspond to the ground state transition. According to the current interpretation the ground state transition has a Q value of −1.122 ± 0.010 MeV. The (d, t) angular distributions and the ratios of (3He, α) and (d, t) cross sections at selected angles were used to determine l values for a number of the transitions. Three states in 149Nd at 481, 813, and 986 keV are definitely populated by l = 0 transitions and thus have Iπ = 1/2+. A strongly perturbed band consisting of a mixture of Nilsson states from the i13/2 shell has been found, with properties similar to the corresponding bands in the isotones 151Sm and 153Gd. The total observed intensity for each of the l values 0, 1, 2, and 6 cannot be explained by the extreme single-particle shell model but is consistent with that predicted by the Nilsson model. However, the splitting of the strength among the observed states cannot be explained by the basic Nilsson model.
A Search for Stimulated Emission of Radiation From Superconducting Tunnel Junctions
Authors: Fife A. A. , Gygax S.
Published: April 2011

A report is made of an exhaustive search for stimulated emission of energy gap radiation from superconducting tunnel junctions of the form Ta–oxide–A1. Two types of radiation detectors have been employed—bolometers for broad band detection and a superconducting frequency converter tunable in the range of interest for narrow band work. The present search has been completely unsuccessful and this negative result has spurred a reexamination of both the theory and the experiments. Serious doubts are raised as to the validity of earlier claims and it is concluded that the previous probable observation of radiative emission requires a different interpretation.
The Effect of Oxygen on Amorphous Films of ZnTe
Authors: Webb J. B. , Brodie D. E.
Published: April 2011

It has been found that oxygen plays an important role in determining the electrical properties of amorphous films of ZnTe. The effects produced by oxygen chemisorption have been studied and reproducible films of amorphous ZnTe (a-ZnTe) have been produced. Thus it is believed that electrical measurements performed on these films will be helpful in determining the conduction processes in them and may lead to a better understanding of the amorphous state in general.
Microtron Supraconducteur : Pertes, Energie de Réfrigération, Courant d'Orbite
Authors: Alaux André , Audet Jean-Claude
Published: April 2011

The superconducting cavities allow us to consider the c.w. operation of a microtron-type accelerator. The authors show here some of the theoretical results they have obtained. This results deal with the losses, the refrigeration energy, and the orbit current.
Electric Dipole Transitions in HD
Authors: Poll J. D. , Karl Gabriel
Published: April 2011

We estimate the amplitude of the Δv = 1 electric dipole transitions in HD to be roughly 8 × 10−5 D.
Zero Bias Resistance Anomalies in Magnesium Tunnel Junctions
Authors: Josefowicz J. , Smith H. J. T.
Published: April 2011

A study of Mg–MgO–Mg tunnel junctions was made with and without Mg particles embedded in the MgO. Zero bias anomalies only occurred when Mg particles were present in the tunnelling barrier.Calculations of the width and the temperature dependence of a zero bias anomaly were made using the Giaever–Zeller model. There is some agreement between the theoretical and experimental values of the width of the anomaly. However, the experimental measurement of the temperature dependence does not agree with the theory.
Spectroscopie par Source Laser. IV. Application de la Théorie d'Anderson au Calcul des Largeurs des Raies de la Transition 10°0–00°1 de N2O. Influence de l'Octupôle sur la Détermination du Moment Quadrupolaire de N2O
Authors: Boulet C. , Lacome N. , Isnard P.
Published: April 2011

From the analysis of the available experimental results, a vibrational dependence of N2O line widths is shown, which can be explained, applying the Anderson–Tsao–Curnutte theory. But no dependence on ν of any of the molecular parameters can be deduced. In the last part, we have pointed out the effect on the determination of the quadrupole moment of assuming a nonvanishing octupole moment for N2O.
Niveaux de Parité Négative de l'16O à Partir de Forces à Trois Corps
Authors: Saunier G. , LeTourneux J. , Rouben B. , Padjen R.
Published: April 2011

We have performed Tamm–Dankoff and RPA calculations of the odd excited states of 16O on the Hartree–Fock basis, using various effective interactions in which a Skyrme-type three-body term simulates the density dependence. We show that although these forces lead to good results for the HF ground state they are not appropriate for odd parity excited states. In particular if the strength of the three-body term is too great, the 2− level becomes imaginary. This in fact occurs for the interaction Vautherin–Brink I, which shows that the spherical HF solution with this force is unstable.
Crystal Dynamics of Rubidium. I. Measurements and Harmonic Analysis
Authors: Copley J. R. D. , Brockhouse B. N.
Published: April 2011

Dispersion curves for lattice vibrations propagating along the five major symmetry directions in a single crystal of rubidium have been measured using inelastic neutron scattering. Care has been taken to identify spurious peaks in the neutron groups and to correct for effects of instrumental resolution. The results, at 12, 85, 120, and 205 °K, have been analyzed within the harmonic framework to yield atomic force constants, which were used to compute the phonon frequency distribution and frequency contours in the (100) and [Formula: see text] planes. A reciprocal space analysis has also been performed. The results are compared with previous measurements on the lighter alkali metals, and with the calculations of Toya and of Price, Singwi, and Tosi.
Instabilities of a Plasma with Anisotropic Ion Temperature Penetrated by the Field of a Helicon Wave
Authors: Teichmann Jiří
Published: April 2011

The contribution studies the behavior of instabilities, excited by the anisotropy of the distribution of ion velocities, in the case of a plasma penetrated by a helicon wave.The modification of dielectric properties of the plasma, induced by the helicon wave, influences substantially the onset of instabilities and reduces their growth rates.Thus a dynamic stabilization for some dangerous microinstabilities, which are based on collective interaction between both plasma species, could be achieved.
A New Electronic Emission System of GeF2
Authors: Martin R. W. , Merer A. J.
Published: April 2011

A new system of weak emission bands in the region 3250–3700 Å is attributed to a transition from an excited triplet state of GeF2 to the ground state; the upper state bond angle is about 112°, and the bending frequency is 191 cm−1. The assignment of the carrier is based on isotopic evidence and the agreement of the lower state bending frequency with that found from the absorption spectrum of GeF2 by Hauge, Khanna, and Margrave.
Magnetic Levitation Forces—Circular Coils
Authors: Puhach P. A. , Atherton D. L. , Castel B.
Published: April 2011

Magnetic vector potential is used to derive lift and drag forces for arbitrary coils moving parallel to infinite conducting slabs. It is shown that at high speed the ratio of magnetic lift-to-drag forces for a circular coil whose diameter is small in comparison with its height above the conducting slab becomes 0.6763(hλ)1/2, where λ = μσv. It is concluded that, in practice, the rounded corners needed on rectangular levitation coils will not alter the magnetic lift-to-drag ratio significantly.
Hartree–Fock and Shell-Model Studies of 56Ni
Authors: Dang G. Do , Rabbat J. A.
Published: April 2011

The structure of the low-lying states of 56Ni is studied in the frameworks of the Hartree–Fock theory and the shell model. Attention is focused on the choice of the single particle energies and the effect of highly excited states. It is found that the low-lying states can reasonably be described by the shell model with 1p–1h and 2p–2h excitations from the 1f7/2 level. A critical discussion of the contradictory results of previous works is made and their connection with the present work is pointed out.
A Quantum Model for Bending Vibrations and Thermodynamic Properties of C3
Authors: Hansen C. Frederick , Pearson Walter E.
Published: April 2011

A quadratically perturbed square well potential is used to derive quantized bending mode vibrational energy levels for the C3 molecule. Coupling with rotational modes and l doubling is neglected for simplicity. The model is constrained to a best fit with observed lower vibrational levels in the lowest rotational state, and subject to this constraint the upper vibrational levels have maximum possible divergence. Thus a lower limit for the partition function and the entropy of C3 is established; the neglected rotational coupling has little influence on these quantities because the splitting of levels is almost symmetrical. The limits obtained support the classical model of Strauss and Thiele for the thermodynamic properties of C3 rather than the estimates listed in current JANAF Thermochemical Tables, and imply that recent graphite vapor pressure measurements made by Zavitsanos and by Wachi and Gilmartin are more correct than earlier measurements.
Two-Dimensional Steady Magneto-Fluid-Dynamic Flows with Orthogonal Magnetic and Velocity Field Distributions
Authors: Chandna O. P. , Nath V. I.
Published: April 2011

The geometries of flows with constant speed along each individual streamline, sonic flows, and flows with isometric nets are determined. Study of two dynamically distinct flows having the same streamline pattern is made. Solutions for vortex, radial, and parallel flows are obtained.
On the London Moment in Rotating Superconducting Cylinders
Authors: Rystephanick R. G.
Published: April 2011

A microscopic treatment, based on the BCS model of a superconductor, of the magnetic field generated inside a rotating cylindrical superconductor (London moment) is presented. The rotation of the superconductor is treated by considering the superconductor to be in an appropriate gravitational field and Bogolubov's self-consistent field method is used to calculate the current generated by the rotation. The field obtained is found to agree with that predicted by other treatments and observed experimentally.
Various Aspects of Divergent Electromagnetic Masses: Analyticity, Scaling, and Light-Cone
Authors: Morita K.
Published: April 2011

Various features associated with the divergent electromagnetic self-mass of a particle are elucidated. Bjorken's original analysis is implemented with a simple convergence theorem which serves as a basis on which various models are discussed regarding their implications on the divergence problem as well as on the scaling property. A simple model of the current commutator function is proposed, on the basis of which it is argued that the quark-model light-cone commutator gives a wrong sign to the divergent self-mass due to its lack of the current conservation. It is also shown that it is the next-to-leading singularities on the light-cone of the commutator that bring forth a (logarithmically) divergent mass shift.
Freezing Parameters for Ice Monocrystals and the Separation of Basal Platelets
Authors: Milosevic-Kvajic M. , Kvajic G. , Brajovic V.
Published: April 2011

Ice was grown unidirectionally upwards from a NaCl solution (0.01–1% by weight) in a temperature gradient (at the interface) of about 10 °C/cm. The freezing rate decreased from an initial value of 5 cm/h to approximately 0.5 cm/h at the end of freezing. This rate was sufficiently small to insure that the temperature gradient was always linear along the ice specimen. The separation of platelets in a cylinder of monocrystalline ice was measured after sectioning perpendicularly to the direction of growth. It was found that the separation depended on the orientation of the c axis with respect to the growth direction. In a monocrystal with the c axis perpendicular to the direction of growth, the separation was proportional to the square root of the "local solidification time"; the proportionality constant increased slightly with concentration.
Lifetime Measurements in Fluorine and Silicon in the Vacuum Ultraviolet
Authors: Irwin D. J. G. , Livingston A. E.
Published: April 2011

We have measured radiative lifetimes for 19 excited levels in F I–IV and Si II–IV by the beam–foil technique. The production of silicon beams by the use of SF6 as the source gas is discussed. The lifetime results are compared with theory and experiment where possible, and 7 new experimental lifetimes are presented.
Search for the First 0+ Excited State in 90Sr
Authors: Singh B. , Johns M. W.
Published: April 2011

Gamma–gamma cascades of the form I–2–0 involving the 2+ state at 831.5 keV in 90Sr have been studied with a NaI(Tl)–Ge(Li) coincidence spectrometer to search for 0+ states in this nucleus. None of the eight cascades examined show the strong anisotropy characteristic of a 0–2–0 cascade. On the basis of these measurements and the beta and gamma transition intensities, the spins of the 1655,1892, and 2207 keV states which had been proposed as candidates for the two-phonon triplet are 4 or 3, 2 or 3, and 3 or 2 respectively. Although unique spin assignments are not possible, the spin 0 choice is completely excluded.
Experimental Study of Wakes Produced by Hypersonic Cones in Free Flight
Authors: Lahaye C.
Published: April 2011

This paper describes an experimental study of the wakes produced by hypersonic cones flying at a velocity of 15 000 ft/s in Range 3 at the Defence Research Establishment Valcartier (DREV). Three basic cone shapes have been flown: 0.7 in. base diameter, 20° included angle cones with sharp and blunted noses, and a 1.0 in. base diameter, 44° included angle sharp nose cone. Because of the complexity of the flow field generated by these cones usually flying at some angle of attack, the experimental study was limited to one set of ambient conditions, namely, a cone velocity of 15 000 ft/s and an ambient pressure of 100 Torr of air.The measurement of the wake velocity distribution by means of the sequential spark technique constituted the backbone of the experimental program on cone wakes. The technique is based on the formation of an ionized luminous path in the wake by a first spark and on the periodic reillumination of the displaced ionized path by successive sparks. Over 100 profiles of velocity were measured behind the cone shapes. Additional diagnostic tools for this study included the photoattitude and velocity measurement system of the range which was used to determine the flight history and to measure the drag coefficient of the models and also the schlieren technique which was used to measure wake growth and deflection. A wealth of original data has been obtained on the behavior of the wake generated by the three different conical models. The measurements have revealed the presence of an asymmetry in the transverse profile of axial velocity and the presence of a lateral velocity component in the wake of high lift to drag ratio cones flying at angle of attack. The variation of the wake axis and wake front velocity with axial distance has been derived and shows good agreement with other theoretical and experimental results. Due to the presence of angles of attack of different amplitude and orientation, it was not possible to determine the transverse distribution of the mean axial velocity. Nevertheless, these results should contribute to a better understanding and also to an accurate modeling of the wake of cones.
The Geometry of the Isomorphic Model of the Closed-Shell Nuclei
Authors: Anagnostatos G. S.
Published: April 2011

The classical part of a new microscopic model of nuclear structure based on high spatial symmetry is proposed. The isomorphic model, as it is called, is a model of the closed-shell nuclei up to 208Pb at the ground state. In brief, it assumes stable dynamic equilibrium of nucleons on spherical shells, which results in shells having average shapes represented by high symmetry polyhedra derived from one another, whose vertices represent average nucleon positions. Properties successfully examined by application of this classical part alone are nuclear shells and magic numbers, nuclear radii, nuclear density, and ground-state moments of inertia of rotating nuclei based on a closed-shell approximation. Through the presentation of this new model, we wish above all to show that symmetry, used as the basis for a nuclear structure model, is highly successful, just as in other areas of physics and chemistry.
Evolution of the CO Vibrational Energy Distribution in a Transverse Flow Laser
Authors: Dawson P. H.
Published: April 2011

Values of the probabilities of vibrational energy exchange among CO molecules are calculated using the long-range force theory and provide the basis for a computer simulation of CO vibrational energy distribution in a transverse flow chemical laser. A comparison with experimental data demonstrates the importance of the very rapid redistribution of energy among high-lying levels due to CO†–CO† interactions and of the role of the chemical by-product OCS in enhancing the population inversion in levels ν = 6 to 10.
Calculation of the Three-Dimensional Rotation Group Representations dm′m(j)(β) for j = 0(1/2)10
Authors: Buckmaster H. A. , Chatterjee R. , Fry D. J. I. , Shing Y. H.
Published: April 2011

The calculation of the explicit forms of the three-dimensional group representation dm′m(j)(β) ≡ d(j;m′,m:β) for j = 0(1/2)10 is discussed. A computer program has been developed which tabulates these forms.
Single Crystals of Ice Grown from KCl Solution and Their Dielectric Properties
Authors: Maeno Norikazu
Published: April 2011

Single crystals of ice were grown from KCl solution and their dielectric properties were investigated as functions of concentration, frequency, and temperature. It was found that a limited amount of chlorine was incorporated into the crystal lattice of ice but no trace of potassium. The upper limit of the substitutional incorporation of chlorine was approximately 1 × 10−4M(g moles/1). The distribution coefficients of the solutes were obtained as functions of the KCl concentration of the mother solution.The static dielectric constant of the single crystals of ice decreased due to the chlorine incorporation and the activation energy of its dielectric relaxation was reduced to 5.8 kcal/mole. The low-frequency conductivity increased with the square root dependence upon the chlorine concentration, and its activation energy was 6.1 kcal/mole. The mechanism of the dielectric polarization and conduction was discussed in relation to the defects introduced by chlorine built in the crystal lattice.
Magnetic Properties of One-Dimensional Dilute Ising Systems. I
Authors: Matsubara Fumitaka , Yoshimura Koh'ichi , Katsura Shigetoshi
Published: April 2011

One-dimensional dilute systems with nearest neighbor interactions are studied in terms of power series of the concentration of magnetic atoms. Recurrence relations between coefficients of the power series of the Ising systems are obtained. The Ising systems of S = 1/2 are studied. The specific heats, the susceptibilities, and the magnetizations of the ferro magnets and antiferromagnets are obtained. At low temperatures, three steps in the magnetization of antiferromagnetic systems are found. An Ising system of S = 1/2 with nearest and second nearest neighbor interactions is also studied by extending the method, and the specific heats are obtained when the magnetic field is zero.
Phonon Drag in the Alkalis
Authors: Hayman B. , Carbotte J. P.
Published: April 2011

We have calculated the effect of phonon drag on the electrical resistivity and the thermopower of the alkali metals. The calculations are an extension of our previous work on select transport properties of the alkalis. For the electron–ion interaction we use the pseudopotentials that we developed from resistivity data. Realistic phonons obtained from inelastic neutron scattering results on the dispersion curves are employed. This means that no adjustable parameters enter our calculations. Good qualitative agreement with experiment is obtained for the phonon drag thermopower.