bluuebunny/crossref_metadata_2025 huggingface dataset:
`Anodic Oxidation of Tantalum
Authors: Wilcox P. S. , Westwood W. D.
Published: April 2011

Anodization current efficiency measurements were used to determine the oxygen content of sputtered tantalum films. Films consisting mainly of b.c.c. Ta had less than 5 at.% oxygen while 'normal' β-Ta contained 10–15 at.% oxygen. Films with a more negative temperature coefficient of resistance had a higher oxygen content.The field strength required to cause oxide growth on 'normal' β-Ta was lower than for b.c.c. Ta films or for oxygen rich β-Ta films. The cause of these changes in field strength is not known. The dielectric constants of the oxides grown on all films were the same, but depended on the measurement conditions and history of the oxide.
First Principles Calculations with the Heine–Abarenkov Model Potential
Authors: Ballentine L. E. , Gupta O. P.
Published: April 2011

A systematic calculation yields several substantial modifications to the Heine–Abarenkov model potential in a metal. Most important are an inhomogeneity correction to the valence–valence exchange and a large change in the energy at which the free ion model potential should be evaluated for an ion in a metal. The agreement with pseudopotentials fitted from Fermi surface data is excellent for Na, Mg, and Al. A discrepancy of about 0.01 Ry exists for K. Because the free ion model potential must be extrapolated quite far below the valence orbital energies, the use of a linear extrapolation is unlikely to be valid for any ion having a d state as its highest core level.
The 0 °K Debye Temperature of Hexagonal Close-Packed Materials
Authors: Pynn R.
Published: April 2011

Expressions for the zero-temperature limit of the Debye temperature of hexagonal close-packed materials are given in terms of the elastic constants. The expressions presented are exact and may be evaluated without resort to the iterative or series-expansion methods previously employed.
Radiative Yield of the Eα = 1.68 MeV Resonance in the 15N(α,γ)19F Reaction
Authors: Dixon W. R. , Storey R. S.
Published: April 2011

The radiative yield of the Eα = 1.68 MeV resonance in the 15N(α,γ)19F reaction has been measured by three different methods. These methods are: (1) a comparison with the Eα = 1.53 MeV resonance in the 14N(α, γ)18F reaction; (2) a comparison with the Ep = 0.898 MeV resonance in the 15N(p, αγ)12C reaction; and (3) an absolute determination based on an efficiency calibration of the detector with a standard radioactive source. The final result is[Formula: see text]
Some Odd Z Nuclei in the 63 ≤ A ≤ 89 Mass Region in the Framework of the Intermediate Coupling Model
Authors: Paradellis T. , Hontzeas S.
Published: April 2011

The level structures of the nuclei 63Cu, 69Ga, 75As, 79Br, 83Rb, and 89Y are investigated in the framework of the unified model.Each nucleus is considered to consist of an even–even vibrating core and extra-core proton quasiparticle. The quasiparticle–core interaction Hamiltonian is assumed to be given by a dipole plus a quadrupole term. The coupling of a g9/2 state to the vibrating core leads to the formation of states of positive parity with [Formula: see text]. Such states with I up to 11/2+ have been recently observed in the nuclei under investigation. In the case of negative parity states the extra core proton quasiparticle is assumed to have available the p3/2, p1/2, and ƒ5/2 states. Many features of the investigated nuclei are explained by the model at least qualitatively. The present calculations do not exhaust the possibility of improved results. Future experimental data will be highly desirable not only for testing but also for improving the model.
K X-Ray and Gamma-Ray Angular Correlations in the Decay of 113Sn and 133Ba, using a High Efficiency Sum-Peak Coincidence Scintillation Spectrometer
Authors: Rao K. Venkata Ramana , Lakshminarayana V.
Published: April 2011

K-capture isotopes 113Sn and 133Ba are used with a sum-peak coincidence scintillation spectrometer arrangement to study the K X-ray – gamma-ray angular correlation. The effects of the type of beta decay, the nuclear environment, and three-gamma cascades with intermediate gamma ray unobserved are investigated. No anisotropy could be detected, supporting the theory of Dolginov.
Dependence of Hartree–Fock Solutions in sd-Shell Nuclei on Spin-Dependent Forces
Authors: Jensen A. S. , Harvey M.
Published: April 2011

The Hartree–Fock solutions and the stabilities of these solutions are examined for all 4n nuclei in the (2s,1d) shell for various strengths of the spin-dependent forces. The relationship with a possible vibrational structure is discussed.
Deconvolution of Experimental Data
Authors: Arsenault Henri , Genestar Bernard
Published: April 2011

We propose a method of deconvolution based upon the sampling theorem. Interlaced samples are used to find the sampled values at the zeros of the transfer function. The space–bandwidth product is used to determine how many independent samples are required to find the required object g(x). The technique eliminates so-called invisible solutions, and gives a unique solution in the absence of noise.
Highly Restricted Partitions and Angular-Momentum States of Equivalent Particle Configurations
Authors: Bose A. K. , Patera J.
Published: April 2011

A simple method is given for determining the angular-momentum multiplets of equivalent particle configurations of symmetry [λ]. The number of times a multiplet occurs in a configuration can be found directly without doing a complete analysis. The problem is reduced to the evaluation of certain partition functions P(τ) (J). As an example the k4 configuration (j = 7) is analyzed. First, the frequency of one multiplet in k4 of any symmetry [λ] is determined and then a complete angular-momentum analysis is made.
Mie Correction to Particle Size Determination by Diffraction Methods
Authors: Patitsas A. J.
Published: April 2011

The effect of the Mie intensity function of a single colloidal 3 μ sphere on the angular positions of the maxima of the interference function of two-dimensional hexagonal arrays of such spheres is examined. The theoretically computed shifts of the maxima correspond very closely to those observed experimentally. Thus, the discrepancy between the packing diameter of the arrays as determined by optical microscopy and as determined from the diffraction maxima is removed.
Generalized Time Response Formulation for Array Fields
Authors: Ormsby J. F. A. , Weiss M. R.
Published: April 2011

An analysis is provided for the far-field transient response of a linear array antenna. The analytic formulation uses a particularly concise vector field integral equation and is generalized in two ways. First, in contrast to earlier work, the effects of fill time and delay time are simultaneously treated and second, the solutions are derived in terms of the far-field impulse response providing closed form expressions for a large variety of input signals.Results are a function of input pulse shape, viewing angle, frequency, and antenna feed mechanism. Specific analytic computations are given for a variety of pulse shapes, antenna illumination functions, and pulse feeds. To illustrate the formulas, particular numerical results and curves are displayed comparing the leading edge transient response of a center-fed system using both rectangular and cosine shaped pulses at two viewing angles.
A Simple Generalization of the Yao Model
Authors: Brown D. J.
Published: April 2011

The Yao model for the process p + p → d + π+ is generalized to the reaction p + p → d + x+ where x+ is an isovector meson.
Surface Relaxations in Cubic Metals
Authors: Jackson D. P.
Published: April 2011

The interplanar surface relaxations of seven face-centered and nine body-centered cubic metals are calculated for their three low index surfaces. In f.c.c. lattices the relaxation for the three surfaces is in the order (110) > (100) > (111) whereas in b.c.c. lattices the order is (111) > (100) > (110). In general the relaxation is greater for b.c.c. metals than for f.c.c. Comparing different metals of the same structure, it is found that the relaxation is closely related to a non-dimensional parameter [Formula: see text], where α and r0 are parameters of the Morse potential.
Spectromètres Electrostatiques. Partie I
Authors: Delage Yves , Carette J.-D.
Published: April 2011

We present a second-order approximation equation for the trajectory of a charged particle in a 1/r electrostatic field. Then a method to evaluate the curve of the energy distribution of the electrons transmitted by an electrostatic spectrometer is proposed. This method is used to evaluate the energy spectrum of two particular cylindrical spectrometers, whose utilization is widely spread in many laboratories. The properties of the electron beam, such as the electron distribution as a function of the exit angle, are studied with the aid of the proposed method of calculation. Also we study the method of analyzing or measuring the electron energy spectrum, as done by experimenters, in order to evaluate the precision of these measurements.
Static Field Induced Spectrum of Hydrogen
Authors: Buijs H. L. , Gush H. P.
Published: April 2011

The fundamental rotation–vibration band of H2 induced by an electric field has been measured at high resolution using an interferometer with a limit of resolution of 0.006 cm−1. The frequencies and the widths of the absorption features have been measured in the density range 1 to 25 amagat, and zero-density frequencies have been obtained by extrapolation. The lines exhibit collision narrowing, the minimum width, 0.01 cm−1, occurring at a density of about 2 amagat. A new value, 1.2 cm3, has been obtained for the matrix element of the polarizability.
On the Form of Truncated Multipolar Expansion Pair Functions
Authors: Jankowski K. , Malli Gulzari , Maysilles J. H.
Published: April 2011

The influence of the form of the radial part of the correlation factor on the properties of the truncated multipolar expansion pair functions has been investigated for the helium atom ground state. A Z-dependence analysis of the energy improvements obtained with different lengths of the multipolar expansion is also presented.
Sensitivity of Nuclear Emulsion at Very Low Temperature
Authors: Johnson A. W. , Hébert C. J. D. , Hébert J. , Lamarche J. L. G.
Published: April 2011

The sensitivity of Ilford G5 emulsion has been studied at very low temperature by comparing the grain density of proton tracks recorded at 0.1 °K and at room temperature. It is found that the emulsion retains (74 ± 2)% of its room temperature sensitivity when exposed at 0.1 °K and that temperature cycling has no noticeable effect on previously recorded tracks.
Transport Phenomena in the Shock Initiation Problem
Authors: Elliott James Parker
Published: April 2011

The collisionless solution of the shock initiation problem is considered. Expressions for the fluid mechanical variables are given for arbitrary initial equilibrium states on either side of the diaphragm. Whereas, in certain special cases, a constitutive law in Navier–Stokes form can be obtained for the stress, no such relationship exists in general. Departure from the Navier–Stokes law is found to be related to gradients in the transverse pressure that come about as a result of the mixing of molecules with different thermal energies. The heat flux is broken down as the sum of a flux of axial energy and a flux of transverse energy. The ratio of the axial flux to the total flux is examined in several cases. Comparison is made with the Chapman–Enskog value, and with the values assumed by other authors in studying the shock structure problem. Departure of this ratio from its near-equilibrium value of 1/3 is suggested as a means of assessing the validity of the collisionless solution. The possibility of extending the Navier–Stokes solution down to small times is discussed.
Instability of a Smooth-Planar Solid–Liquid Interface on an Ice Crystal Growing from a Melt
Authors: Kvajić G. , Pounder E. R. , Brajović V.
Published: April 2011

The solid–liquid interface morphology of an ice crystal was observed during upward vertical growth as a function of the freezing rate and the initial impurity concentration of NaCl. The following changes in morphology were seen: smooth-planar interface → low density irregular "lines" on vertical C axis (CV) and "lines" parallel to the basal planes on horizontal C axis (CH) crystals → high density of these "lines" → high density of thin "steps" on the CV and "dots" and "ridges" on the CH crystals → low density of thick steps on the CV and vertical platelets on the CH crystals. This instability of smooth-planar interface morphology cannot apparently be accounted for by constitutional supercooling theory, and the recent perturbation theory of a smooth-planar interface can explain the existence of substructures ("steps", "dots", "lines") in some but not all cases. The majority of the experimental observations are not explained by these theories.
Larmor Precession of the First Rotational Level of 181Ta
Authors: Keszthelyi L. , Cameron J. A. , Santry D. C.
Published: April 2011

Perturbed angular correlation measurements have been made on the decay of 181Hf implanted in iron. The average integral rotation angle for the 136 keV 9/2+ state of 181Ta is ωτ = 0.051 ± 0.004 rad. For the internal field on Ta in iron of 640 kOe, this gives a nuclear g factor of 0.27 ± 0.04. Alternative explanations of the small rotation are discussed. The E2/M1 mixing ratio of the 136 keV transition was found to be δ = −0.44 ± 0.04.
Magnetic Rotation and Absorption Spectra of cis and trans Acrolein
Authors: Bair E. J. , Goetz W. , Ramsay D. A.
Published: April 2011

Six bands have been observed in the magnetic rotation spectrum of acrolein at 4040, 4069, 4122, 4178, 4220, and 4322 Å. The first five bands are assigned to the 3A″–1A′ (π*–n) transition of trans acrolein with the 0–0 band at 4122 Å. The sixth band at 4322 Å is assigned as the 0–0 band of the 3A″–1A′ (π*–n) transition of the cis (or gauche) isomer. The 3A″ state of the cis (or gauche) isomer lies below the corresponding state of the trans isomer by a similar interval to that found earlier for the 1A″ (π*–n) states. The reverse situation exists for the ground states.The absorption spectrum has also been reinvestigated using up to 30 m atm of gas in a cell heated to 180 °C. New assignments are given for some of the bands.
Sealed CO Laser at Room Temperature
Authors: Seguin H. J. , Tulip J. , White B.
Published: April 2011

A small sealed off CO laser has given over 10 W continuous at room temperature. Preliminary results indicate that upon optimization, performance equivalent to that of the sealed off CO2 laser will be realized.
Inelastic Electron Scattering from 18O
Authors: Groh J. L. , Singhal R. P. , Caplan H. S. , Dolbilkin B. S.
Published: April 2011

The inelastic electron scattering cross sections for the excitation of the levels in 18O lying below 6.0 MeV have been measured in the momentum transfer range 0.5 < q < 1.0 fm−1. Excitation of the following T = 1 levels was observed: 1.98 MeV (2+), 3.63 MeV (0+), 3.92 MeV (2+), 4.45 MeV (1−), 5.09 MeV (3−), 5.25 MeV (2+), and 5.33 MeV (0+). Estimates of transition probabilities to the ground state have been made through a parameterization of the data using the generalized Helm model. Longitudinal form factors calculated from the wave functions of Benson and Irvine show excellent agreement with the experimental form factors.
High-Field Stark Effects on the Near Ultraviolet Spectrum of the Hydroxyl Radical
Authors: Scarl Ethan A. , Dalby F. W.
Published: April 2011

Spectra due to the A2Σ+–X2Π transition of the hydroxyl radical in electric fields of over 300 000 V per cm have been obtained. The dipole moment of the A2Σ+ ν = 0 state of OH has been determined to be (1.98 ± 0.08) D. From the variation of the dipole moment with vibrational quantum number in the 2Π state, the transition probability for the pure vibrational transition ν = 1 →ν = 0 has been estimated to be A10 = 80s−1.
Librational Motion in the α Phase of Solid N2 and CO
Authors: Goodings D. A. , Henkelman M.
Published: April 2011

The librational motion in the α phase of solid N2 and CO has been studied in the approximation that the centers of mass of the molecules are fixed at the lattice sites (i.e. no translational motion). The potential between two molecules in the crystal was taken to be that derived by Kohin modified slightly to ensure that the molecules are in equilibrium at the measured lattice spacing at T = 0. This potential was expanded in the angle deviations of the molecules from their equilibrium orientations, and the librational frequencies at zero wave vector were calculated in the harmonic approximation. The results were found to be as much as 1.9 times higher than the frequencies measured by Raman scattering. This is attributed mainly to the failure of the harmonic approximation rather than to lack of knowledge of the parameters in the potential. This conclusion is supported by a simple calculation of the root mean square angular deviation of a molecular axis from its equilibrium orientation which for α-N2 is estimated to be 18° at T = 0. Finally, it is emphasized that the anisotropic attractive and repulsive dispersive terms and the quadrupole–quadrupole interaction make comparable contributions to the librational frequencies.
Radiation Through a Stratified Plasma with a Dielectric Window
Authors: Sivaprasad K. , Celikkol B.
Published: April 2011

The input admittances of a pair of identical rectangular slot antennas radiating through a square dielectric window which is covered with an inhomogeneous plasma layer has been studied using a modal expansion of the fields. General expressions for the input admittance of a single aperture and mutual admittance between slots arbitrarily located under the window are given. Proper approximations used to simplify the field calculations within the window are discussed.
Investigations on the External Problem of Alpha Decay
Authors: Ixaru Liviu Gr.
Published: April 2011

The origin of this paper was the assumption that the approximations which are currently used when calculating the barrier penetration factor of the R-matrix theory of alpha decay are largely responsible for the major discrepancies between theoretical and empirical absolute decay rates. The author examines in detail two of them, namely the JWKB approach and the neglect of the alpha particle size. He shows that, in the daughter nucleus surface region, the JWKB approximation is a fairly accurate one except in an interval of about 1 fm thickness centered at the inner turning point. As concerns the neglect of the alpha particle size, it is also found to be an accurate approximation. Based on these results, as well as on the results of other papers dealing with the theory of alpha decay, the author speculates that the aforementioned discrepancies could be seriously diminished only provided one renounces the standard view of the alpha decay mechanism. Continuing on this line he introduces a new decay model. He investigates the external problem corresponding to this model and shows that it leads to an enhancement of the penetrabilities by a factor of 30 to 40. Some arguments in favor of this model are also given.
Time of Arrival Operator
Authors: Razavy M.
Published: April 2011

The problem of finding proper quantal operators for the time of arrival, when the source is at infinite distance from the detector, is investigated. It is shown that at least two Hermitian operators can be constructed which, in the Hilbert space of positive energy spectrum, are self-adjoint. The spectra of these operators are continuous and their eigenfunctions form an orthonormal set.
Liquid Helium and the Properties of a Bose–Einstein Gas. IV. The Effect of Various Approximations
Authors: Goble D. F.
Published: April 2011

On a qualitative basis we have examined the identification of the properties of a hard-core Bose–Einstein (BE) gas with those of liquid helium four below the lambda temperature. It is suggested that the use of the generalized condensation of Girardeau together with the inclusion of "three-body ladders" from the perturbation series may improve the agreement between the hard-core BE model system and the physical helium four system to such an extent that reasonable quantitative agreement may be attained.
Electron Spin–Spin Contact Interaction and Mass-Variation and Darwin Relativistic Corrections in Isoelectronic Series
Authors: Lo B. W. N. , Saxena K. M. S. , Fraga S.
Published: April 2011

The values of the total electron spin–spin contact interaction and the mass-variation and Darwin relativistic corrections have been calculated for a number of isoelectronic series. It is observed that the main contributions to these corrections, that are not negligible, are made by the inner electrons.
CW Standing-Wave Linacs and Transverse Beam Blowup
Authors: Aboul-Atta O. A.
Published: April 2011

The beam interaction with transverse magnetic (TM11-like) modes in standing-wave linear accelerators leads to the phenomenon of beam blowup whenever the average beam current exceeds a critical value. Previous theories that estimate a lower bound for that threshold current neglect the interaction of the neighboring modes in the periodic structure. A more realistic estimate has been developed that carefully includes the effect of the coupling on the damping mechanism and takes into consideration all factors influencing the system response. Developed results supply the designers with the various parameters that could be varied, should higher values than the previously mentioned threshold current be needed. The reported analysis takes care of a complete tank length of coupled cells with emphasis on the side-coupled structures for their distinct advantages in machines of high current capacity. The physics of the oscillation mechanism is cast in one final formulation with known transient solution. The external force function is made available for discussing the steady-state solution when the pulse frequency is a submultiple of the resonance frequency, which causes the off-centered beam to be deflected and usually puts one of the constraints on beam focusing.
Resistivity and Thermopower of a Series of Ni–Fe Invar Alloys
Authors: Armstrong Barry E. , Fletcher Robin
Published: April 2011

The resistivity and absolute thermopower of a series of commercial f.c.c. Ni–Fe alloys containing 36–51 at. % Ni plus a comparison alloy of 75 at. % Ni have been measured over the range 1.5–125 K. Both the residual and the temperature dependent resistivities show a dramatic increase as the Ni concentration is reduced. By combining the present thermopower results with those at high temperatures by Kolomoets and Vedernikov, it is found that a pronounced maximum in the absolute magnitude of the thermopower occurs at a temperature of the order of 200–400 K. The results have been interpreted in terms of the 'weak ferromagnet' band model. Spin-mixing is briefly discussed and shown not to be of primary importance in these alloys.
Computing Salinity Profiles in Ice
Authors: Fertuck L. , Spyker J. W. , Husband W. H. W.
Published: April 2011

The ratio of ice salinity to brine salinity, k, has been measured at temperature gradients up to 1.3 °C/cm. The data obtained have been found to fit the empirical equation k = 0.1 + 0.293 dt/dx. This equation was used in a digital simulation of the freezing process and the results were compared with data obtained in field experiments in a temperate climate. The computed ice salinities were within 25% of measured salinities at any particular level in ice having a horizontal c axis, and the computed average ice salinity was within 5% of the actual average ice salinity.Under the climatic conditions of the experiment this equation was found to be more accurate than an equation derived by Weeks and Lofgren.
Gaussian Wave Functions and the Many-Body Problem
Authors: Hall R. L.
Published: April 2011

A system of identical nonrelativistic particles is considered. It is shown that the wave functions for relative motion, which have the correct permutation symmetry, must satisfy two functional equations. In the case of bosons these equations are solved for those bound states where the wave function is also in a single-product form. The only solutions are Gaussian functions. Consequently these are the only functions which can reduce the N-body energy expectation to an integral over a single variable. Furthermore, we show that our reduced two-body Hamiltonian which in general gives energy lower bounds yields the exact energy of the entire system only for the Hooke's law interaction. Neither possibility is allowed by fermions.
Numerical Study of Nonequilibrium Diagram Theory
Authors: Dowling Gary R. , Davis H. Ted
Published: April 2011

In this paper we numerically analyze the first few diagrams in a Boltzmann-like collision operator that occurs in Severne's exact kinetic equation for the singlet distribution function. A similar analysis was used by Allen and Cole in deriving their singlet and doublet kinetic equations. Our analysis shows that the diagrams neglected by Allen and Cole in their kinetic equations are not negligible and these should be incorporated into dense fluid theories. The Allen–Cole kinetic transport coefficients and equilibrium pair correlation function are presented and calculated for dense argon. These results are not promising.
Langmuir Probes in Plasma with Anisotropic Velocity Distributions
Authors: Tokutaka H. , Frood D. G.
Published: April 2011

The electron temperature measured by a flat-plate Langmuir probe in a plasma with an elliptically anisotropic distribution function is shown to be related in a simple manner to the electron temperatures on the principal axes of the distribution function and to the orientation of the plate with respect to these axes. Velocity anisotropy would be most readily measured using the AC modulation technique in conjunction with a rotatable probe.
Accurate Numerical Hartree–Fock Self-Consistent-Field Wave Functions for La+, Tm+, and Yb+
Authors: Saxena K. M. S.
Published: April 2011

Accurate numerical Hartree–Fock (HF) self-consistent-field (SCF) wave functions have been obtained for La+(4ƒ16S)3F and 1F, Tm+(4ƒ136S)3F and 1F, and Yb(4ƒ146S)2S rare-earth ions. In general, the total energy values have an accuracy of seven figures, the virial theorem is satisfied to seven significant digits, and the radial wave functions are self-consistent and without tail oscillations to three decimals. Several Hartree–Fock parameters are also evaluated with these functions.
Domain Configurations, Bloch Walls, and Magnetization Processes in Iron Whiskers from D.C. to 200 kHz. Theory and Experiment. I
Authors: Heinrich B. , Arrott A. S.
Published: April 2011

Bloch walls in iron whiskers have been studied by direct magnetization measurements. Of several types of domain configurations the simplest, the Landau structure, is readily identified from the a.c. permeability. The behavior of this structure over a wide range of frequencies is accounted for by a model which treats the wall as an elastic membrane attached to two springs on its ends. The stiffness is shown to be magnetostatic in origin. The elastic wall is shown to be damped in its motion by eddy currents. The qualitative aspects of the behavior are well accounted for and some numerical consistencies are found.
Schottky-Energy Calculation: Relation between Force-Balance and Energy-Minimization Procedures
Authors: Simpson J. H.
Published: April 2011

An attempt is made to determine whether the variations between results of Schottky-energy calculations in the literature arise chiefly from the parameters used or from the method of attacking the problem. Results of the force-balance and energy-minimization methods of calculating the displacements of the ions surrounding the defect and the dipoles upon them are compared. It is concluded that the differences are small and explicable provided the same set of crystal parameters is used. The reasons for some of the discrepancies in the literature are discussed.
Scattering by Spherically Symmetrical Objects
Authors: Shafai L.
Published: April 2011

The solutions of vector potentials in the presence of spherically symmetric objects are expressed in terms of two auxiliary functions, related respectively to the phase and amplitude of the resulting field. It is shown that these auxiliary functions satisfy first-order differential equations of the radial coordinate, and the scattered field is described by the phase functions alone. Furthermore, the differential equations satisfied by the phase functions are found to be independent of the amplitude functions and are solved numerically by using the well-known initial phase shifts readily obtained from the boundary conditions.
Measurements of Neutron Polarizations for Deuteron Energies from 0.87 to 5.00 MeV
Authors: Smith J. R. , Thornton S. T.
Published: April 2011

Neutron time-of-flight techniques have been used to measure [Formula: see text] polarization angular distributions for several deuteron energies from 0.87 to 5.00 MeV. Liquid helium served as the polarized neutron analyzer. From Legendre polynomial expansions of σ(Θ) and P(Θ)σ(Θ), contour maps of P(Θ) and P2(Θ)σ(Θ) have been produced for the energy range 0.87 to 5.00 MeV. Comparison with previous results and measurement techniques are discussed. Nucleon polarizations from the charge symmetric reactions [Formula: see text] and [Formula: see text] are compared.
Nonleptonic Weak Decays of Hyperons and the Algebra of Currents
Authors: Yakimiw E.
Published: April 2011

It is known that a large parity-violating spurion contribution in the Kumar–Pati theory on nonleptonic weak hyperon decays is not consistent with the theory. We have re-examined the case wherein the spin-3/2+ decuplet and the [Formula: see text] singlet contributions are taken into account. The best χ2 fit in this model leads to an uncomfortably large contribution of the [Formula: see text] to the parity-conserving [Formula: see text] amplitudes, which cannot be lowered by introducing a {27}-plet weak spurion effect. Thus we are faced with the two alternative theories: either the SU(3)-symmetry breaking is negligibly small [Formula: see text], the μ/λ octet weak spurion ratio is low [Formula: see text], and the parity-conserving [Formula: see text] contribution is high (more than 90% of the [Formula: see text] amplitude), or the SU(3)-symmetry breaking is important[Formula: see text], the μ/λ ratio is high [Formula: see text], and the parity-conserving [Formula: see text] contribution is small (less than 30% of the [Formula: see text] amplitude).
Space Groups for Fermi Surfaces
Authors: Jan J.-P.
Published: April 2011

All possible Fermi surfaces, in the repeated zone scheme, have the symmetry of one of 24 symmorphic space groups. These groups are tabulated, and a procedure is given to determine the point symmetry of special positions in the Brillouin zone.
Polarizability of a Bias–Temperature Drifted Species in Thin Film Transistor Structures
Authors: Webb J. B. , Brodie D. E.
Published: April 2011

Instabilities in thin film transistors have been observed and it has been possible to isolate each instability in samples and study its effect separately. An instability involving the trapping and freeing of electronic charges from trapping centers in the bulk of the insulator has been observed. Control over this instability has been achieved with the aid of bias–temperature (B–T) stress cycles, and the transistor performance altered by introducing relatively stable trapping centers into the insulator. By manipulating the charge state of these centers, the polarizability of the drifted species forming the centers in the matrix of the insulator has been determined. This permits the calculation of a classical radius for the trapped electrons in the host insulator and agreement between the experimental value, and the value calculated using a hydrogen-like impurity model is good. The polarizability for sodium in SiOx has been observed to be from 1.1 to 3.4 × 10−36 F/m and 4.8 to 6.3 × 10−36 F/m for sodium in ZnS.
Electric Quadrupole Transitions in Na I, Mg II and Al III
Authors: Tull C. E. , Jackson M. , McEachran R. P. , Cohen M.
Published: April 2011

Theoretical multiplet strengths for electric quadrupole transitions between 2S, 2P0, 2D, and 2F0 levels of Na I, Mg II, and Al III have been calculated using Hartree–Fock wave functions of frozen-core type. The resulting 2S–2D oscillator strengths for Na I are in good agreement with calculations by Bogaard and Orr, Boyle and Murray, and Warner; however, for Mg II there is a discrepancy of a factor of 2 between our results and those of Warner.
The Effect of Contact Annealing on Hall Data for MoS2 Layer Structures
Authors: Souder A. D. , Brodie D. E.
Published: April 2011

The effect of contact annealing on Hall data obtained from thick layer structured samples of MoS2 (i.e. β > 2) is presented. A more meaningful determination of the carrier concentration is obtained from these samples if either the contact is annealed at 800 K for 10 min or the concept of an effective sample thickness is used. The carrier concentration in an n-type natural crystal obtained from Korea is 2.6 ± 0.5 × 1016 cm−3 at room temperature and remains relatively constant down to 100 K.
Spectra of H2–Ne and D2–Ne Van der Waals Complexes in the Collision-Induced Fundamental Bands of Hydrogen and Deuterium
Authors: McKellar A. R. W. , Welsh H. L.
Published: April 2011

Spectra of H2–Ne and D2–Ne Van der Waals complexes accompanying transitions in the collision-induced fundamental bands of hydrogen and deuterium have been obtained with an absorption path of 110 m at temperatures around 27 K in a specially designed multiple-traversal cell. The observed structure is similar to that of H2– and D2–Ar, Kr, and Xe complexes studied earlier, but the number of lines observed for the Ne complexes is fewer because of the shallower intermolecular potential. Well-resolved R and P branches (Δl= ±1, where l is the rotational quantum number of the complex) accompanying the overlap-induced Q1 (0) transitions are analyzed directly to give rotational (B) and centrifugal stretching (D) constants for the complexes. Unlike the other H2– rare gas complexes the spectra accompanying quadrupole-induced transitions show no direct evidence of anisotropy of the intermolecular forces.
Emission Spectrum of the PO Molecule. Part III. Spectrum in the Red Region
Authors: Guha S. , Jois S. S. , Verma R. D.
Published: April 2011

Four new bands in the red region are observed which have been described in terms of A2Σ+–B2Σ+ and F2Σ+–B2Σ+ systems. A rotational analysis together with deperturbation calculation of one band at 6763 Å has shown that A2Σ+ (ν = 7) and F2Σ+ (ν = 0) vibrational levels are involved in a homogeneous perturbation. The rotational structure study of three bands of a new transition I2Σ+–A2Σ+ has been carried out. From the study of heterogeneous perturbations observed in the I vibrational levels, it has been suggested that the perturbing state is a 2Π state arising from the 3d complex.
The Mg2 Potential: A Curve Fitting Study
Authors: Brett Arthur C. , Chan Chorkin
Published: April 2011

Data defining the ground state potential energy curve of the 24Mg2 molecule in the region of the potential minimum have been fitted with Morse, Lennard–Jones 6–12, Lippincott, Morse 6–8, and generalized Lennard–Jones a–b and a–b–6–8 functional forms. The Morse 6–8 function yielded the best fit.
Anomalous Annihilation of Positrons in Several Solid Hydrocarbons
Authors: DeBlonde G. , Chuang S. Y. , Hogg B. G. , Kerr D. P. , Miller D. M.
Published: April 2011

In previous experiments with positrons annihilating in liquid organic materials (Hogg et al.) the measurements of IN (intensity of the low momentum component from angular correlation data) and I2 (intensity of the long lived component from lifetime measurements) have resulted in IN = I2/3 within experimental error.For samples of CH4, C6H6, and C6H12 measurements in the liquid state yield the expected equality between IN and I2/3. However, in the solid state for these substances there is a marked disagreement between IN and I2/3. The value of IN, in all cases, is essentially zero suggesting that no positronium is formed, but the value of I2 remains large.
Nocturnal and Semiannual Variations of the Intensity of 5577 Å Emission of Atomic Oxygen
Authors: Pal S. R. , Shah G. M.
Published: April 2011

The observed features of 5577 Å emission in night glow at Mt. Abu (India) have been presented. The midnight maximum of 5577 Å emission has been associated with the large scale circulations in the lower thermosphere. The seasonal variation of this emission is discussed in relation with the semiannual variation in the thermospheric heating.
Kaon Electromagnetic Form Factor in a Veneziano-Type Representation
Authors: Chia T. C.
Published: April 2011

A simple form of kaon electromagnetic form factor in a Veneziano-type representation is investigated. With the conjecture of Yang et al. and Elitzur's scaling hypothesis for hadronic form factors, the kaon form factor is linked to and compared with high energy K + P → K + P and K + P → K*P scattering data. The results are found to be satisfactory.
Silver Film Atomic Oxygen Sensors
Authors: Thomas Ronald J. , Baker Doran J.
Published: April 2011

Measurements indicate that the initial oxidation rate of a thin film of silver is linearly proportional to the atomic oxygen flux; however, the oxidation coefficient is dependent upon the technique for depositing and chemically reducing the thin film. A model is developed relating the conductance of a thin-film sample to its oxidation. The measurements and the model indicate that the silver film is very promising as a sensor of upper atmospheric atomic oxygen. The model also indicates that the surface recombination coefficient of atomic oxygen depends on the oxide thickness as well as the flux.
On the Hyperon–Nucleon Interaction
Authors: Satoh E.
Published: April 2011

The effect of the ΛΣ conversion on the binding energy of a Λ particle in infinite nuclear matter is estimated by using phenomenological hyperon–nucleon potentials. All the potentials are assumed to be central and are set up to fit the low–energy ΛN and ΣN scattering including the Λp resonance below the ΣN threshold. In these potentials more realistic ranges than those in recent papers are used.
Détermination du Champ de Vitesse du Sillage d'une Sphère Hypersonique à l'Aide de Peignes de Sondes Ioniques
Authors: Sévigny L. , Heckman D. , Emond A.
Published: April 2011

The technique of measuring convection velocity in the hypersonic wake with a pair of in-line probes has been applied on a large scale to the mapping of the velocity field in the hypersonic wake through the use of a transverse survey array containing up to 8 ion-probe pairs. Measurements are reported of the velocity field in the wakes of 2.7 in. diameter spheres flown at 14 500 f/s in ballistic range atmospheres at 7.6 Torr and at 20 Torr of nitrogen. The array technique leads to convection velocity results which are in excellent agreement with the mean wake velocity data obtained by the sequential spark technique in an air atmosphere. In addition, the technique has permitted an extension of the mapping of the velocity field of 15 000 f/s spheres to considerably smaller axial distances than was possible with the spark method because of the difficulty of forming distinct sparks at the higher levels of ambient ionization encountered in the near wake.A comparison of the data obtained at 7.6 Torr and at 20 Torr shows that the amplitude of the velocity distribution in the wake, as defined by the velocity on the wake axis, is higher at higher pressure. Considering the wake width, however, it is found that the width of the velocity distribution is larger at the lower pressure of 7.6 Torr than is the case at 20 Torr, at least in the near wake. However, at axial distances greater than 300 or 400 diameters, the data for the two pressures tend to overlap. These observations appear to be related to other information indicating that for 2.7 in. diameter spheres launched at 7.6 Torr, the wake is not fully turbulent until about 300 or 400 diameters.
Nouvelle Méthode de Mesure de la Visibilité de la Modulation Spectrale pour de Grandes Différences de Marche
Authors: Delisle Claude , Brochu Michel
Published: April 2011

A novel method for determining the visibility of the spectral modulation in a white light interference experiment is described. Essentially, one measures the ratio of the total intensity to the sum of the intensities of the individual beams at the exit of a system composed of two interferometers in series. Contrary to the usual method, the novel one is applicable to any path difference. In practice, the method has been tried for a path difference up to 23 cm. This limit has been imposed by the maximum displacement of the movable mirror of the interferometer. The experiment shows that the visibility of the spectral modulation of a white light source is still very high for a path difference as large as 23 cm.
The Observation of Incipient Phase Transitions in K2PtCl6, K2PdCl6, and K2IrCl6
Authors: Armstrong Robin L. , Driel Henry M. Van
Published: April 2011

Measurements of the temperature dependence of the nuclear quadrupole resonance (NQR) frequencies and spin–lattice relaxation times for the 35Cl nuclei in Cs2PtCl6, Rb2PtCl6, K2PtCl6, and K2PdCl6 provide information on the temperature dependence of two averages of the rotary lattice mode frequency over the-Brillouin zone. An iterative method is introduced to analyze the NQR frequency data and simultaneously yield the static lattice resonance frequencies and the temperature dependence of one of the average rotary mode frequencies. The results show that previous analyses of the data yielded erroneous values of the static lattice resonance frequencies. What is more interesting, the analysis presented clearly indicates incipient phase transitions in both K2PtCl6 and K2PdCl6 but shows that the structures of Cs2PtCl6 and Rb2PtCl6 remain stable to 0 K. The interpretation of the relaxation time data yields the temperature dependence of the second average rotary mode frequency and substantiates the conclusions drawn from the frequency data. A comparison of data for K2PtCl6 and K2IrCl6 reveals an incipient phase transition in the latter substance as well.
Collision-Induced Absorption of H2 and He–A Mixtures near λ = 1 mm
Authors: Cunsolo S. , Gush H. P.
Published: April 2011

The spectrum of compressed H2 and a He–A mixture has been measured from 4 to 50 cm−1. A sudden drop in absorption intensity below 10 cm−1 is attributed to reversal of the dipole moment in successive collisions.
Theory of Electromagnetic Reflection from a Parallel Grid of Dielectric Coated Wires Buried in the Earth
Authors: Wait James R.
Published: April 2011

Using a boundary-value treatment, a solution is obtained for the plane wave reflection from a grid of thin insulated wires buried in a homogeneous conducting half-space. A key step in the analysis is the use of an approximate impedance condition to relate the total current in the insulated grid wires and the axial component of the total electric field. Full account of the interaction of the fields with the air–ground interface is also achieved. The final result, for the specular component of the scattered field, is shown to be consistent with an equivalent transmission line circuit. The latter may also be used to predict the effect of a layer of snow or ice on the ground.
Kinetic Models and Brillouin Scattering in a Molecular Gas
Authors: Boley C. D. , Desai Rashmi C. , Tenti G.
Published: April 2011

Within the framework of the Wang Chang–Uhlenbeck kinetic equation, we propose a model description of molecular gases. The model is related to the models earlier discussed by Hanson and Morse. In our formulation, the model requires no adjustable parameters to analyze the light scattering spectrum from a molecular gas. We apply the model theory to recent Brillouin scattering experiments on hydrogen, deuterium, and hydrogen deuteride and find excellent agreement.
Rotational Analysis of Bands of the Transition of PH2
Authors: Berthou J. M. , Pascat B. , Guenebaut H. , Ramsay D. A.
Published: April 2011

Rotational analyses have been carried out for the 0ν′20–000 bands of the [Formula: see text] electronic transition of PH2 with ν′2 = 1–8. Approximately 1000 lines have been assigned. The earlier analysis of the 000–000 band has been extended and improved molecular constants obtained. The Hamiltonian used for this band does not fit the excited state levels with [Formula: see text]. Term values are therefore given for all observed levels. Empirical formulas are presented which give approximate fits to the higher levels. Numerous rotational perturbations are found in the excited state. Perturbations up to 0.6 cm−1 are also found in the 000 level of the excited state. These latter perturbations can only be caused by the higher vibrational levels of the ground state.
Calculations of Angular Distributions from Metals using Positron Wave Functions with Proper Crystal Symmetry
Authors: Gould A. G. , West R. N. , Hogg B. G.
Published: April 2011

A positron wave function incorporating the proper crystal symmetry is calculated and applied to the determination of that part of the angular distributions arising from the annihilation of core electrons in Cu, Cd, and Zn. The core electrons are treated in the tight binding approximation while the conduction electrons are assumed to be free. The resulting distributions are found to be in better agreement with experiment than those of previous independent particle calculations.
Level Structure of Spin State in the Presence of a Phonon Field
Authors: Savard J.-Y.
Published: April 2011

Calculations are made of a spin manifold in interaction with a single mode phonon field. The effect of the interaction is taken care of by the introduction of a shift operator. An equivalent Hamiltonian is derived which is then diagonalized.
Excitation Transfer Process in Self-Broadening
Authors: Zaidi H. R.
Published: April 2011

The effect of the excitation transfer process on Doppler broadening is investigated in a gas of identical radiators. This effect can be described by a linear transport equation, which also includes the self-broadening. The resulting line shape exhibits shift, asymmetry, and some narrowing. The basic equations can be easily generalized to include the usual collisional narrowing.
The Electrostatic Potential in a Finite Ionic Crystal
Authors: Redlack A. , Grindlay J.
Published: April 2011

An expression is obtained for the electrostatic potential in a system in which similar charges are distributed over all the points of a s.c. lattice, contained within an ellipsoidal surface. The potential consists of two components: one, the intrinsic potential, is (a) a periodic function of position, with the period of the lattice, (b) a function of the geometry of the lattice, and (c) independent of the size and shape of the ellipsoid; the other, the extrinsic potential, is, (a) independent of the geometry of the lattice, (b) a quadratic function of position, and (c) a function of the shape and size of the ellipsoid. The intrinsic potential is shown to be equal to the Ewald transformed potential at high symmetry points (cube corner, face centers, body center).The finite crystal potential results are applied to the case of an electrically neutral point charge model of a cubic ionic crystal. Both the electrostatic potential within the crystal and the electrostatic energy per charge repetition unit prove, in general, to exhibit nonzero extrinsic components. The special cases of the slab-shaped specimen with CsCl. NaCl, and BaTiO3 structure are discussed.Harris and Monkhurst's expression for the energy per ion pair in an infinite diatomic ionic crystal of point charges is shown to be equal to the intrinsic component of the energy per ion pair for the finite crystal.