bluuebunny/crossref_metadata_2025 huggingface dataset:
SCATTERING OF ELECTROMAGNETIC WAVES BY A SINUSOIDALLY STRATIFIED HALF-SPACE: I. FORMAL SOLUTION AND ANALYTIC APPROXIMATIONS
Authors: Tamir T. , Wang H. C.
Published: April 2011

A detailed investigation of the scattering of a plane wave incident on a periodically stratified medium is presented. The periodic medium occupies the x > 0 region, and the stratification occurs along the z direction and is produced by a sinusoidal modulation of the dielectric constant. By choosing the polarization parallel to the y coordinate, the fields in the stratified medium appear as solutions of a wave equation of the Mathieu type. The geometry employed herein is shown to serve as a basic configuration for a large number of applications dealing with optical–acoustic interactions, reflection gratings, periodic antennas, and others. The modulated half-space therefore represents a canonical problem which leads to rigorous solutions for the present polarization and to good approximations for the alternative polarization.By viewing the solution in terms of waves of the Floquet type, it is shown that the field consists of modes that travel independently and are coupled to each other only at the air–dielectric interface. The coupling mechanism is represented in terms of an equivalent network which lends insight into both qualitative and quantitative aspects of the diffracted field. Graphical constructions using dispersion diagrams, which greatly facilitate the understanding and interpretation of various field properties, are presented. Explicit analytic results are obtained for small modulation and it is shown that the field is then given primarily in terms of only three modes. When only one mode propagates in each half-space region, the interface network reduces to a simple circuit with interesting properties. While possessing considerable interest by themselves, the present results also form the basis for an extensive investigation of the field behavior at the Rayleigh and Bragg regimes. The latter aspects will be discussed in Part II of this study.
A COMPLETE VARIATIONAL WAVE FUNCTION FOR THE GROUND STATE OF 3H AND 3He
Authors: Banville Marcel , Kunz P. D.
Published: April 2011

The three-body wave function for particles of equal mass is expanded in a systematic way by making use of a hyperspherical coordinate system. Apart from the center-of-mass coordinates, three of the variables are the usual Euler angles describing the orientation of the plane defined by the three particles. The other three variables, which describe the shape of the triangle, are represented in terms of a radial coordinate and two angular coordinates. The kinetic energy for these last three coordinates is separable and allows one to expand the three-body wave function in a complete set of orthogonal functions based upon the angular variables. The particular symmetry of the internal part of the wave function under permutations of the three particles is easily represented in terms of the set of functions for one of the angular variables. By choosing a particular set of radial functions one can then obtain the upper limit on the binding energy for the three-body system through the Rayleigh–Ritz variational procedure. The advantage of this particular coordinate system is that all but a few of the variational parameters occur linearly in the wave function, and the minimum energy can be obtained by diagonalizing a small number of the energy matrices. The method is applied to find the lower limit to a standard spin-independent potential of Gaussian shape.
THE SCREENING FUNCTION OF AN INTERACTING ELECTRON GAS
Authors: Geldart D. J. W. , Vosko S. H.
Published: April 2011

The screening function of an interacting electron gas at high and metallic densities is investigated by many-body perturbation theory. The analysis is guided by a fundamental relation between the compressibility of the system and the zero-frequency small wave-vector screening function (i.e. screening constant). It is shown that the contribution from a graph not included in previous work is essential to obtain the lowest-order correlation correction to the screening constant at high density. Also, this graph gives a substantial contribution to the screening constant at metallic densities. The general problem of choosing a self-consistent set of graphs for calculating the screening function is discussed in terms of a coupled set of integral equations for the propagator, the self-energy, the vertex function, and the screening function. A modification of Hubbard's (1957) form of the screening function is put forward on the basis of these results.
LOW-TEMPERATURE NEUTRON-IRRADIATION DAMAGE AND ITS RECOVERY IN HIGH-PURITY GERMANIUM
Authors: Swanson M. L.
Published: April 2011

Neutron-irradiation damage at 1.9 and 4.2 °K and its recovery to 300 °K were investigated in high-purity germanium by means of photoconductivity measurements. It was observed that the photoresistivity increased linearly with the irradiation time up to doses of 5 × 1012 fission–neutrons/cm2 for samples containing approximately 7 × 1013 impurity atoms/cm3, but that some saturation occurred for less pure samples (containing 1015 impurity atoms/cm3). Almost complete recovery of the irradiation-induced changes in photoresistivity of the higher-purity n- and p-type samples occurred in three stages, centered at 32, 95, and 180 °K. The results were independent of the method and degree of carrier excitation. The damage rates and recovery were explained in terms of the recombination of photocarriers through the simple vacancy and interstitial-type defects which were created by the irradiation and were subsequently removed by thermal migration.
INTERNAL GRAVITY-SHEAR WAVES IN THE TROPOSPHERE: I. PHASE VELOCITIES
Authors: Naito Keikichi
Published: April 2011

The theory of internal gravity-shear waves in the troposphere is examined for two- and three-layer models of air density and horizontal velocity. It is shown that models having continuity in air density across the internal boundaries are not satisfactory for analysis involving first-order perturbations. The complexity of the analysis increases rapidly with the introduction of a gradient in the model density, and with additional layers in the model. The phase velocities of internal waves of wavelength between 100.m and 10 000 m are calculated for three simple models; the long-wavelength predictions agree favorably with observations by Gossard and Munk. No comparison is available for the shorter wavelengths.
THE LOW-TEMPERATURE THERMAL CONDUCTIVITY, ELECTRICAL RESISTIVITY, AND THERMOELECTRIC POWER OF DILUTE SILVER ALLOYS WITH MANGANESE
Authors: Malm H. L. , Woods S. B.
Published: April 2011

Low-temperature measurements of electrical resistivity, thermal conductivity, and thermoelectric power on silver alloys containing 0.005, 0.067, 0.11, and 0.31 at.% of manganese are reported. The same specimens were used for the measurement of all properties over the temperature range from 2 to 25 °K. The well-known minimum and maximum are observed in the electrical resistivity of the three more concentrated alloys and the minimum is visible in the most dilute alloy near the lowest temperatures of measurement. Associated effects are observed in the other properties and their possible relationship to theoretical electron scattering mechanisms, particularly that of Kondo, is discussed.
RADIATION FROM A SPHERICAL ANTENNA WITH AN ANISOTROPIC PLASMA SHEATH
Authors: Wait James R.
Published: April 2011

The boundary-value problem for a concentric spherical system consisting of an infinitesimally thin shell of magnetoplasma surrounding a source-excited slotted sphere is solved. The solution is carried out in some detail under the assumption that the properties of the sheath do not vary with the angular coordinates. It is indicated that the anisotropy of the sheath introduces a cross-polarized component of the radiated field. The extension to a sheath, with a spatial variation of its properties, is outlined briefly.
ELECTRON PARAMAGNETIC RESONANCE OF Ti3+ IONS IN TlAl(SO4)2∙12 H2O
Authors: MacKinnon John A. , Dionne Gerald F.
Published: April 2011

The paramagnetic resonance spectrum of Ti3+ ions in thallium alum (TlAl(SO4)2∙12 H2O) single crystals has been studied in the {100} planes at 4.2 °K with an X-band microwave spectrometer. The spectrum is an analogue of that reported by Dionne for Ti3+ ions in rubidium alum (RbAl(SO4)2∙12 H2O), but differs in that the lines occur at lower values of the magnetic field, and that no superhyperfine splitting was observed. As in the case of Rb alum, the spectrum was explained by considering a model of 12 magnetic complexes, the complexes being related to each other through the symmetry elements of the [Formula: see text] point group of the alum lattice. The three g factors for the spin Hamiltonian with [Formula: see text] were found to be 1.938, 1.834, and 1.790—within an accuracy of ± 0.005. The three different g factors were taken as evidence for a crystal electric field of orthorhombic symmetry. The orbital energy-level splittings required to give the observed g factors were calculated by a degenerate perturbation method. Since the crystals were colorless and since no value for 10 Dq is available in the literature, a unique set of splitting parameters could not be obtained. By giving the spin-orbit coupling constant λ values between 150 and 110 cm−1, a range of crystal-field energy-level splittings was determined, all of which predict that the cubic splitting 10 Dq is in the ultraviolet region of the frequency spectrum.
THE (n, p) CROSS SECTIONS OF TITANIUM ISOTOPES FOR NEUTRON ENERGIES BETWEEN 13.6 MeV AND 19.5 MeV
Authors: Pai H. L.
Published: April 2011

Using enriched titanium samples, the activation (n, p) and (n, pn; n, np; n,d) cross sections have been measured for the five isotopes of titanium in the neutron energy range from 13.6 to 19.5 MeV. The results were compared with calculations based primarily upon Bodansky's theory (1962), where the first proton emission cross section was taken to be the sum of (n, p) and (n, pn). The (n, pn) cross section was separated from the experimental (n, pn; n, np; n, d) cross section by a multiple-emission calculation. Using the nuclear temperature derived from the experimental data, good agreement was achieved between experiment and theory. It was found that the parameters of Bodansky's equation for the titanium isotopes could be adopted directly from the mass parabolas (Dewdney 1963). It was also found that the (n, p) cross sections were not influenced appreciably by the neutron closed shell.
ELECTROMAGNETIC FIELDS OF A DIPOLE OVER AN ANISOTROPIC HALF-SPACE
Authors: Wait James R.
Published: April 2011

An oscillating electric dipole located over a homogeneous anisotropic conducting half-space is considered. The conductivity tensor is taken to have a simple diagonal form which is appropriate for a finely stratified medium. Expressions for the electromagnetic fields are derived for both vertical and horizontal dipole excitation. It is shown that the horizontally polarized fields are independent of the vertical component of the conductivity. On the other hand, the vertically polarized fields are influenced both by the horizontal and the vertical components of the conductivity. The results have possible application to electromagnetic investigations of the earth's crust and in radio propagation studies.
CALCULATION OF THE ELECTRONIC STRUCTURE OF LIQUID METALS
Authors: Ballentine L. E.
Published: April 2011

The density of states and momentum distribution of conduction electrons in liquid metals are calculated for Al, Zn, and Bi. The theory used is a perturbation expansion of the Green function in the independent particle model. The structure factor a(K) is taken from X-ray (Al, Zn) or neutron (Bi) scattering experiments, and the screened-ion model potential u(K) of Heine and Abarenkov (1964) is used. The results indicate that if the zero of u(K) is very near the main peak of a(K), as in Al and Zn, the electronic structure is nearly free-electron-like. But if u(K) is significantly large at the peak of a(K), as in Bi, there will be significant departures from the nearly free electron model.
GRAVITATIONAL COLLAPSE AND WEAK INTERACTIONS
Authors: Arnett W. David
Published: April 2011

The behavior of a massive star during its final catastrophic stages of evolution has been investigated theoretically, with particular emphasis upon the effect of electron-type neutrino interactions. The methods of numerical hydrodynamics, with coupled energy transfer in the diffusion approximation, were used. In this respect, this investigation differs from the work of Colgate and White (1964) in which a "neutrino deposition" approximation procedure was used. Gravitational collapse initiated by electron capture and by thermal disintegration of nuclei in the stellar center is examined, and the subsequent behavior does not depend sensitively upon which process causes the collapse.As the density and temperature of the collapsing stellar core increase, the material becomes opaque to electron-type neutrinos and energy is transferred by these neutrinos to regions of the star less tightly bound by gravity. Ejection of the outer layers of the star can result. This phenomenon has been identified with supernovae.Uncertainty concerning the equation of state of a hot, dense nucleon gas causes uncertainty in the temperature of the collapsing matter. This affects the rate of energy transfer by electron-type neutrinos and the rate of energy lost to the star by muon-type neutrinos.The effects of general relativity do not appear to become important in the core until after the ejection of the outer layers.
MUTUAL DIFFUSION IN POLAR–NONPOLAR GASES: KRYPTON – SULPHUR DIOXIDE AND KRYPTON – DIETHYL ETHER
Authors: Srivastava B. N. , Saran Anil
Published: April 2011

The interdiffusion coefficients for the gas mixtures of Kr–SO2 and Kr–(C2H5)2O have been measured in the temperature range 1 to 45 °C by the two-bulb technique of Ney and Armistead using radioactive 85Kr as tracer. A scintillation counter has been used for analyzing the concentration of 85Kr at different times. A mass correction was applied to get the normal diffusion coefficients for both the systems.The experimental D12 values have been employed to get the unlike interaction parameters on the Lennard-Jones (12:6) potential and compared with those obtained by using the combination rules for a polar–nonpolar system and the force constants of the polar gas from viscosity as well as from second virial data. For interpreting second virial data for polar gases the assumption of an off-center dipole is found to yield better interaction parameters.
ANISOTROPY OF THE ENERGY GAP IN SUPERCONDUCTING LEAD–BISMUTH ALLOYS
Authors: Campbell C. K. , Dynes R. C. , Walmsley D. G.
Published: April 2011

Tunneling techniques have been applied to a study of the remanent anisotropy of the energy gap in superconducting Pb–Bi alloys. The relationship between anisotropy and mean free path L is discussed for situations in which L is well inside the "dirty" superconductor limit (L ~ ξ0).
FREE-FALL DIFFUSION IN A DISCHARGE AFTERGLOW
Authors: Gregory B. C.
Published: April 2011

The afterglow decay of the number density and electron temperature of a plasma in which collisions between electrons and molecules are rare is studied both theoretically and experimentally. The theoretical approach, using the first three moment equations solved in a one-dimensional geometry, predicts non-exponential decay profiles in time for both density and temperature. Experimental results are obtained using a cylindrical mercury vapor discharge tube at pressures where the mean free path of the electrons is much larger than the transverse dimensions of the tube. The average electron number density is measured by a surface-wave cavity method and the electron temperature by means of Langmuir probes. The theoretical and experimental results are in good agreement, especially for the density decay.
RADIATION EFFECTS IN PRECISION RESISTANCE THERMOMETRY: II. ILLUMINATION EFFECT ON TEMPERATURE MEASUREMENT IN WATER TRIPLE-POINT CELLS PACKED IN CRUSHED ICE
Authors: McLaren E. H. , Murdock E. G.
Published: April 2011

The heating effect of normal laboratory illumination on the sensors of standard platinum resistance thermometers immersed in a standard water triple-point cell packed in crushed ice has been investigated. This study shows that the absorption by the platinum sensors of luminous and near-infrared radiation transmitted through the ice pack could easily amount to temperature errors as large as 0.000 5 °C. Any illumination error must be eliminated by making all measurements in the dark or under adequate radiation shielding.
THE DECAY OF 89Rb
Authors: Kitching J. E. , Johns M. W.
Published: April 2011

The decay of 14.9-minute 89Rb to levels in 89Sr has been studied by use of Ge(Li) detectors, NaI(Tl) detectors, and a magnetic beta-ray spectrometer. Fourteen gamma rays have been studied by γ−γ and β−γ coincidence experiments and establish levels at 0, 1.031, 2.000, 2.277, 2.567, 2.708, 2.770, 3.225, and 3.500 MeV. The Q value is 4.486 ± 0.012 MeV. The γ−γ and β−γ data were analyzed by a nonlinear least-squares fitting technique, which is described.
ELECTRON MICROSCOPE OBSERVATION OF ATOMIC PLANES AND ATOMIC POSITIONS IN GERMANIUM
Authors: Parsons J. R. , Hoelke C. W.
Published: April 2011

One factor limiting the resolution of crystal lattice planes in the electron microscope is hydrocarbon contamination of the specimen during observation. This problem was minimized by rebuilding the Siemens Elmiskop 1 vacuum system. With the new system the best operating vacuum attainable in the microscope was improved from 1 × 10−5 Torr to 1.2 × 10−7 Torr. The corresponding contamination rate was reduced from 2 Å/second to 0.1 Å/second. Using this vacuum system and operating the microscope at 100 kV with pointed filaments, both single and crossed lattice images of atomic planes in germanium were obtained. Single lattice images were obtained in which the 3.26 Å spacing of the (111) planes was resolved. Atomic positions were revealed in the crossed lattice images by the intersection of two sets of (111) planes and one set of (200) planes of spacing 2.83 Å.
BANDE DE VIBRATION–ROTATION ν1 + ν4 DE L'IODURE DE MÉTHYLE TRIDEUTÉRIÉ VERS 4 500 cm−1 : MISE EN ÉVIDENCE D'UNE RÉSONANCE DE FERMI
Authors: Joffrin C. , Thanh Nguyen Van , Barchewitz P.
Published: April 2011

The perpendicular band (ν1 + ν4) of CD3I was recorded with a Czerny-type spectrometer, the resolving power of which was about 80 000 in the spectral range. Some rotational constants have been found, and the Fermi resonance between the ν1 + ν4 and ν4 + 2ν5 components pointed out.
CONDUCTION BAND OF GaSb
Authors: Harland H. B. , Woolley J. C.
Published: April 2011

Measurements of transverse magnetoresistaiice and Hall effect have been made on various single-crystal n-type samples of GaSb at magnetic fields of up to 2.4 W/m2 and temperatures in the range 4.2–300 °K. An analysis of the results gives values and the temperature dependence for electron concentration n and electron mobility μ for both (000) and [Formula: see text] minima of the conduction band, the energy separation ΔE of (000) and [Formula: see text] minima, and a value for the effective mass m1* of electrons in the [Formula: see text] minima. Values of ΔE0 = 0.084 eV, d(ΔE)/dT = +0.8 × 10−4 eV/°C and m1* = 0.43 me are obtained, while the ratios of the electron mobilities μ0/μ1 lie in the range 5–21. The total number of observed electrons in the two bands, n0 + n1, is found to vary with temperature, and this result is interpreted in terms of an impurity level above the (000) minimum.
ELECTRON SPIN RESONANCE OF Fe+3 IN CORDIERITE
Authors: Hedgecock N. E. , Chakravartty S. C.
Published: April 2011

ESR spectra of Fe+3 located at one of the aluminium sites in cordierite have been investigated at X- and K-band frequencies at room temperature. The spectra exhibit large zero-field splitting and have been fitted to a spin Hamiltonian of orthorhombic symmetry, having constants b20 = 14.6 ± 0.1 kG, b22 = 8.5 ± 0.1 kG, and isotropic g = 2.004 ± 0.002.
DEPENDENCE OF CRACK FORMATION ON CRYSTALLOGRAPHIC ORIENTATION FOR ICE
Authors: Gold L. W.
Published: April 2011

Observations are reported of crack propagation in columnar-grain, polycrystalline ice subjected to constant compressive load applied perpendicular to the long axis of the columns. About three-quarters of the cracks observed were transcrystalline and the remainder occurred at grain boundaries. The plane of the cracks tended to be parallel to the direction of the applied load. Transcrystalline cracks tended to propagate either parallel or perpendicular to the basal plane. At least two-thirds of the grain boundary cracks were associated with boundaries for which the slip plane of one or both of the adjacent grains was close to parallel or perpendicular to the boundary. It is shown that the observations are consistent with the hypothesis that a minimum number of independent slip systems are required for a grain to conform to an arbitrary deformation under constraints imposed by neighboring grains.
METHOD OF REDUCING SIDE LOBES OF DIRECTIVE ANTENNAS
Authors: Lader Leon J. , Winderman Jay B.
Published: April 2011

The appropriate treatment of the surface of a directional antenna with an r-f. absorption material makes available an additional variable for smoothly tapering the phase and amplitude distribution of a directive antenna, and consequently for controlling the beam pattern. This loss taper, where system considerations warrant it, may be used for the reduction of side lobes in existing antennas, or it may be included, initially, as a factor in design.In support of the concept, analysis and limited experimental investigations were carried out. A 5.5-dB reduction in the side-lobe level of an optimally focused paraboloidal antenna was accomplished with a modest experimental effort. In accord with the analysis, greater improvements should be achievable.
ON THE DEGENERACY PROBLEM IN SU(3)
Authors: Chew C. K. , Sharp R. T.
Published: April 2011

The recent suggestion of Macfarlane, O'Raifeartaigh, and Rao that mixed Casimir operators be used to resolve the external degeneracy problem is applied to the group SU(3). The significant operator is the part of the cubic mixed Casimir operator which is antisymmetric with respect to the two factor spaces and also with respect to starred and unstarred variables. The matrix of this operator is derived with respect to a convenient set of functions and is found to have a simple form. The eigenfunctions are simply related to the usual symmetric and antisymmetric functions in the case of degeneracy 2 with equal factor representations.
ELECTRON TRANSPORT AND THERMOELECTRIC PROPERTIES OF N-TYPE Bi1.75Sb0.25Te3
Authors: Muir W. B. , Chiang P. T. , Champness C. H.
Published: April 2011

The Seebeck and Hall coefficients, the electrical and thermal conductivities, and the figure of merit, Z, have been measured as a function of dopant concentration of n-type CuBr-doped Bi1.75Sb0.25Te3. A maximum room-temperature value of Z = 2.65 × 10−3 °K−1 was obtained for a 0.08 wt % CuBr dopant concentration. The lattice thermal conductivity calculated by using exact statistics and assuming acoustic lattice scattering had a value of 0.011 W cm−1 °K−1. It was confirmed that each CuBr molecule donated a single electron to the conduction band and that about 2 × 1019 cm−3 residual acceptors were present in the alloys. The electron concentration and effective mass were independent of temperature between 100 and 300 °K and the effective mass was independent of carrier concentration between 5 and 60 × 1018 electrons cm−3. The conductivity mobility had a value of 480 cm2 volt−1 sec−1 at 300 °K which was independent of carrier concentration, and a T−3/2 temperature dependence between 100 °K and 300 °K.
APPROXIMATE MOLECULAR ORBITALS: I. THE 1sơg AND 2pơu STATES OF H2+
Authors: Cohen M. , McEachran R. P.
Published: April 2011

Simple analytic representations of the wave functions of the lowest even and odd σ states of H2+ have been obtained using perturbation theory. Their accuracy is demonstrated by comparing the values of a number of molecular quantities computed using the approximate functions with the corresponding exact values.
PLANE WAVE SPECTRA IN GRATING THEORY: V. SCATTERING BY A SEMI-INFINITE GRATING OF ISOTROPIC SCATTERERS
Authors: Millar R. F.
Published: April 2011

Integral relations satisfied by the scattering function for a semi-infinite grating of isotropically scattering elements are obtained by specializing the results of earlier work. It is shown that the scattering function for the grating may be expressed simply in terms of a function f of one complex variable which satisfies a nonlinear integral equation analogous in form to Chandrasekhar's integral equation. The function f is proportional to the scattering function for the first element of the grating; it also satisfies a more simple functional equation for which a solution has been given elsewhere. The relationship between the present work and the recent analysis of Hills and Karp is examined; except for one minor point, general agreement is found. The difference between the scattering functions for an element in the semi-infinite grating and the corresponding element in the infinite grating is investigated, and its order of magnitude as a function of position in the structure is estimated. An explicit solution (which may be identified with the Sommerfeld half-plane solution) is obtained in the limit as the spacing between elements tends to zero. The scattered far field is examined, special attention being given to the limiting forms in circumstances which correspond to the Rayleigh wavelengths of the infinite grating. It is demonstrated that the form of f depends radically upon whether or not the grating constant is a multiple of a half-wavelength of the incident plane wave; in each case, the behavior of f near its singularities is determined. Some required properties of the scattering function for an element in the infinite grating are obtained. In particular, it is shown that if the grating constant is less than a half wavelength, then this function has poles at certain complex angles of incidence which depend both on the cross-sectional dimensions of a cylinder and on the grating constant. These poles might correspond to resonances in the grating.
GUIDED WAVES SUPPORTED BY LAYERS OF A LOSSY COMPRESSIBLE PLASMA
Authors: Galejs Janis
Published: April 2011

A planar slab of isotropic compressible lossy plasma is bounded either by free space on both sides or by free space and a ground plane, and is excited by line sources. After the dispersion relations have been established, the power carried by the waves is calculated. The total power of the many waves which depend on the resonances of the plasma waves in the transverse dimension of the slab is about two orders of magnitude lower than the power of the surface waves guided along the plasma boundary for frequencies which are somewhat higher than the plasma frequency. The excitation efficiency of the transversely resonant waves is decreased for thick layers of a lossy plasma, but the losses can be neglected if the layer thickness is of the order of the free-space wavelength and the loss tangent of the plasma is less than 0.01.
THE EFFECT OF CRYSTALLINITY AND BOMBARDMENT DOSE ON THE PENETRATION OF 40-keV XENON IONS IN IONIC CRYSTALS AND CERAMICS
Authors: Whitton J. L. , Matzke Hj.
Published: April 2011

The range and depth distributions of 40-keV xenon ions in single crystals of NaCl, KBr, MgO, SiO2 (α quartz), in sintered UO2 and in fused silica, have been measured by the sectioning techniques of vibratory polishing and chemical dissolution. Channeling is observed in the single crystals when the [Formula: see text] is oriented parallel to the incident beam of the ions. This effect is similar to that previously reported for some metal single crystals. High bombardment doses produce a factor of 2–5 decrease in penetration depth in MgO and SiO2, materials which are known to be damaged by ion bombardment. This decrease is smaller in materials that do not show gross ion bombardment damage, such as NaCl, KBr, and UO2. Thus, the study of ranges is shown to be another means of detecting gross radiation damage.
DIFFRACTION BY AN IMPEDANCE HALF-PLANE IN AN ANISOTROPIC PLASMA
Authors: Breithaupt R. W.
Published: April 2011

The problem solved previously by Jull (1964) for a perfectly conducting half-plane is extended to the case of an impedance half-plane. As assumed by Jull, the direction of the incident wave is normal to both the magnetostatic field and the diffracting edge. The plasma is characterized by a permittivity tensor; and only the TM incident field is considered, as the anisotropy does not affect an incident TE wave. The impedance boundary condition is found to introduce unidirectional surface waves propagating at some angle into or away from the surface, as well as the usual radiated far fields.
REFLECTANCE OF GaAs, GaP, AND THE GaAs1−x Px ALLOYS
Authors: Thompson A. G. , Woolley J. C. , Rubenstein M.
Published: April 2011

The reflectance of GaAs, GaP, and the GaAs1−x Px alloys has been measured between 2.5 eV and 20 eV at room temperature and between 2.5 eV and 6 eV at liquid-nitrogen temperature. The transitions E1, E1 + Δ1, Ecp, E0′, E2, E1′, E1′ + Δ1′, and d1 have all been observed and their behavior as a function of alloy composition is presented. The data have been used to give a more detailed picture of the band structure of GaAs and GaP and of the way in which the band structure varies with alloying. In particular, the spin-orbit splittings of the valence band are discussed and the relevance of the 2/3 spin-orbit splitting law considered.
ON THE PROPAGATION OF ELECTROMAGNETIC WAVES IN A PLASMA WITH NEGATIVE IONS
Authors: Teichmann Jiří
Published: April 2011

Small-amplitude electromagnetic wave propagation has been studied in a collisionless plasma containing electrons and positive and negative ions having a different charge-to-mass ratio. The Chew–Goldberger–Low approximation is used for an unbounded, homogeneous plasma in a uniform magnetic field under the assumption of charge neutrality. The analysis of the dispersion relation shows new branches of oscillations, in the zero-temperature limit as well. The classification of waves is presented using the Clemmow–Mullay–Allis diagrams calculated for several plasmas of interest: the laboratory Cs+ Cl− and Cl+ Cl− plasmas and plasma forming the D layer in the ionosphere. New resonances and stop bands have been found for the right-hand polarized wave and the extraordinary wave in the low-frequency region. The isotropic wave propagation at the crossover frequencies and for degenerate plasma is discussed.The dynamics of particles is discussed and the frequency regions in which the positive and negative ions move in opposite phase are given.
THE TEMPERATURE DISTRIBUTION PRODUCED BY ACOUSTIC ABSORPTION: II. BOLTZMANN EQUATION APPROACH
Authors: Simons S.
Published: April 2011

A calculation is given of the time-independent temperature distribution produced by the absorption of an acoustic wave under conditions in which the mean free path of the thermal particles is of the order of the specimen dimensions. Results are obtained for plane geometry by solving the relevant Boltzmann equation with a relaxation time approximation for the collision term. The results suggest an experimental method for obtaining the mean free path of electrons in metals at low temperatures, similar in some respects to the method of conduction in thin films.
THE FORBIDDEN I1Σ−–X1Σ+ ABSORPTION BANDS OF CARBON MONOXIDE
Authors: Herzberg G. , Simmons J. D. , Bass A. M. , Tilford S. G.
Published: April 2011

The forbidden I1Σ−–X1Σ+ transition of CO has been observed in absorption at high resolution in the vacuum ultraviolet region. As expected for a 1Σ−–1Σ+ transition, the bands consist of single Q branches, in which the lines of lowest J are either missing or very weak. Although the selection rule prohibiting Σ−–Σ+ transitions is rigorous for dipole radiation at zero rotation, the I1Σ−–X1Σ+ transition can occur for higher rotational levels because of Coriolis interaction with the A1Π state, which lies very close to the I1Σ− state.Eight bands of the I–X system have been analyzed and from them the rotational and vibrational constants of the I1Σ− state have been determined. Previous information on this state was based entirely on the study of perturbations in the A1Π state. The corresponding perturbations in the I1Σ− state have now been observed. In addition, small "vibrational" perturbations in the ν = 4 and 5 levels (probably caused by interactions with the a3Π state) are found.
THE VELOCITY OF ELASTIC WAVES IN IODINE
Authors: Leith R. M. , Critchlow P. R.
Published: April 2011

The velocities of longitudinal and transverse elastic waves have been measured in iodine at 5 and 10 Mc/s. Using a pulse technique, measurements were made in the temperature range between 1 and 373 °K. The temperature dependence of the velocities is as expected, the transverse velocity being essentially constant while the longitudinal velocity increases with decreasing temperature. The elastic constants have been calculated from the velocity data. A value for the Debye characteristic temperature is evaluated and compared with that deduced from the available specific-heat data.
THE STRUCTURAL BASIS OF FERROELECTRICITY IN COLEMANITE
Authors: Hainsworth F. N. , Petch H. E.
Published: April 2011

The complete structure of colemanite, CaB3O4(OH)3∙H2O, in both its nonpolar and ferroelectric phases, has been determined by neutron diffraction. This work shows that one of the hydrogen atoms of the water molecule and the hydrogen of an adjacent hydroxyl group, which are in a state of dynamic disorder in the nonpolar phase, settle into ordered noncentric positions in the ferroelectric phase. The ordering of the hydrogen atoms is accompanied by small displacements of the other atoms from the positions they occupy in the nonpolar phase. Assuming reasonable charge assignments, the magnitude of the spontaneous polarization calculated from the observed positional changes is of the same order of magnitude as the experimental value. On the basis of these results, a model for the atomistic mechanism of the transition to the ferroelectric state is advanced.
CHARGE DENSITIES AT THE NUCLEUS
Authors: Malli Gulzari , Fraga Serafin
Published: April 2011

The electronic densities and their derivatives at the nucleus for neutral atoms, positive ions, and negative ions (for Z = 2–36) have been evaluated, using analytical Hartree–Fock functions. These values confirm the discussion given in regard to the selection of the basis sets to be used in the expansion of the orbitals.
SPIN-LATTICE RELAXATION BY THE DIRECT PROCESS OF Fe3+ IN POTASSIUM COBALTICYANIDE
Authors: Weissfloch C. F.
Published: April 2011

The spin-lattice relaxation time of dilute potassium ferricyanide was measured as a function of the orientation of the static magnetic field in three orthogonal planes at 9.4 GHz and 1.75 °K.A calculation of the spin-phonon Hamiltonian applicable to the case of three Kramer doublets degenerate with respect to the cubic component of the crystalline bond is given. The theory was applied to the ferricyanide on the basis of Van Vleck's point-charge model.Despite the fact that the ferricyanide complex is known to be considerably covalent, it is found that the theory gives a satisfactory prediction of the observed angular dependence.
ON AN AMBIGUOUS INTEGRAL IN QUANTUM ELECTRODYNAMICS
Authors: Pugh Robert E.
Published: April 2011

An integral that appears in several contexts in quantum electrodynamics is evaluated without the usual ambiguity. The result is applied to (1) the contribution of vacuum polarization to the interpolating photon field, (2) wave-function renormalization, and (3) a gauge-independent formulation of quantum electrodynamics. In the first two cases the expected results are obtained, while in the last case the particular formulation is shown to be, in fact, not gauge invariant.
THE ORTHOGONALITY ASSUMPTION IN THE HARTREE–FOCK APPROXIMATION
Authors: Froese Charlotte
Published: April 2011

Several procedures are considered for maintaining orthogonality between one-electron functions of the nsn's1S excited states as well as orthogonality to a lower state. The results are compared with those obtained without any orthogonality constraints.
ELECTRON DENSITIES OF 8–100 ELECTRONS CM−3 DEDUCED FROM ALOUETTE II HIGH-LATITUDE IONOGRAMS
Authors: Hagg E. L.
Published: April 2011

Alouette II topside ionograms recorded at high latitudes (L ≈ 6 or greater) and high altitudes (1 500–3 000 km) show an interference pattern between the electron gyro and the electron hybrid resonance spikes, when the electron density at the satellite is very low.This interference pattern can be used to determine the electron number density at the satellite, to an accuracy of better than 10% when the electron density is less than about 100 electrons cm−3. Preliminary results show that electron densities less than 30 electrons cm−3 occur over the region north of about 60 °N. geomagnetic latitude and that the southern boundary of the region where the very low electron densities are observed shifts south by about 8° between noon and midnight.
ALPHA–BETA PHASE TRANSITION IN Mn2+-DOPED Mg2P2O7
Authors: Melkvi Z. , Stager C. V. , Calvo C.
Published: April 2011

The specific heat of (Mg1−XMnx)2P2O7 was measured in the vicinity of the alpha–beta phase transition for [Formula: see text]. The temperature and character of the phase transition were found to depend on the composition of the sample and the method of preparation. The results are discussed with relation to the crystal structures of Mg2P2O7 and Mn2P2O7.
A 9-GHz, SINGLE-KLYSTRON, EPR SPECTROMETER USING SUPERHETERODYNE DEMODULATION
Authors: Buckmaster H. A. , Dering J. C.
Published: April 2011

A 9-GHz electron paramagnetic resonance (EPR) spectrometer, which features superheterodyne demodulation using a single klystron as the source of both the sample cavity and local oscillator (LO) power, is described. It uses a reflection cavity as part of a balanced bridge and operates in the absorption mode. The LO power is derived from the microwave carrier power source by a ferrite single side-band generator driven at a very low intermediate frequency (IF) 0(103–106) Hz. This spectrometer uses triple synchronous demodulation at the microwave, intermediate, and field modulation frequencies to overcome the instability usually associated with superheterodyne instrumentation. The sensitivity of the resulting demodulation system has a stability that is essentially independent of fluctuations in the degree of bridge balance and the instantaneous sample cavity resonant frequency, provided that the microwave power source is simultaneously phase-locked to a high stability, MHz crystal oscillator and to the instantaneous resonant frequency of the sample cavity. The sensitivity has been found to remain within 5% of a constant value for periods in excess of 30 days. No readjustments were necessary during this period because of the system stability inherent in this design. The environmental temperature of the spectrometer was maintained at 20 ± 2 °C. Experimental details are given and the results of a sensitivity study are presented graphically.
IONIZATION ENERGY AND IMPURITY BAND CONDUCTION OF SHALLOW DONORS IN n-GALLIUM ARSENIDE
Authors: Basinski J. , Olivier R.
Published: April 2011

Hall effect and resistivity measurements have been made in the temperature range 4.2–360 °K on several samples of n-type GaAs grown under oxygen atmosphere and without any other intentional dopings. The principal shallow donor in this material is considered to be Si. All samples exhibited impurity-band conduction at low temperature. Electron concentrations in the conduction band were calculated, using a two-band model, and then fitted to the usual equation expressing charge neutrality. A value of 2.3 × 10−3 eV was obtained for the ionization energy of the donors, for donor concentration ranging from 5 × 1015 cm−3 to 2 × 1016 cm−3. The conduction in the impurity band was of the hopping type for these concentrations. A value of 3.5 × 1016 cm−3 was obtained for the critical transition concentration of the impurity-band conduction to the metallic type.
ESR STUDY OF THE EFFECT OF UNIAXIAL STRESS ON THE BAND STRUCTURE OF CdS:I
Authors: Slagsvold B. J. , Schwerdtfeger C. F.
Published: April 2011

The shift with uniaxial pressure in the g value of the ESR signal obtained from conductive iodine-doped CdS has been measured at ≈ 1.7 °K. For pressures parallel to the c axis, an average change in the g tensor of ≈ 9.4 × 10−7 cm2/kg was found, while for perpendicular pressures [Formula: see text] shifted an average of ≈ 4.4 × 10−7 cm2/kg. These shifts have been ascribed to a change in the energy gap separating the conduction-band minimum from the valence bands. They, as well as the change in the optical band gap with hydrostatic pressure as measured by Langer (1960), could be fairly well described by the approximate values 6.3 eV/unit longitudinal strain and 1.8 eV/unit transverse strain of the deformation potential constants for the gap.
ON THE ASYMPTOTIC KINETIC EQUATION FOR INHOMOGENEOUS PLASMAS
Authors: Guernsey Ralph L.
Published: April 2011

The equations for the pair correlation of a slightly inhomogeneous plasma obtained under two different forms of Bogolubov's assumptions are solved and the results are shown to be identical. The results are then compared with the corresponding result for the initial value problem. The contribution of the latter to the kinetic equation is shown to relax slowly [Formula: see text] to the asymptotic (in the sense of Bogolubov) result. The present result differs from that of Wu and Rosenberg, who appear to have linearized their equations improperly.
PHOTOIONIZATION AND ABSORPTION COEFFICIENTS OF NO IN THE 600 TO 950 Å REGION
Authors: Metzger P. H. , Cook G. R. , Ogawa M.
Published: April 2011

Absolute photoionization and absorption coefficients of nitric oxide gas have been measured in the 600 to 950 Å region, using a 1-meter Seya-Namioka scanning vacuum ultraviolet monochromator. The Hopfield helium continuum background source was used with photoelectric detection of the dispersed light. Numerous peaks in both the photoionization and absorption spectra were observed at wavelengths that agree well with those of a higher-resolution photographic spectrum. Underlying continua were separated into the ionization and dissociation continua, and the efficiencies for preionization were estimated for those bands previously identified. Weak fluorescence was observed when the wavelength of the incident light was shorter than 677.4 Å. The wavelength of the emitted radiation was found to fall between the cutoff of LiF and quartz.
ENERGY-GAP VARIATION IN MIXED III–V ALLOYS
Authors: Thompson A. G. , Woolley J. C.
Published: April 2011

Values of E0, the lowest direct optical transition, are available for several III-V alloy systems, from measurements of optical absorption, electroreflectance, electroluminescence, etc. It is shown that in all available cases the variation of E0 with composition can be fitted very well to an equation of the form E0 = A + Bx + Cx2, where x is the mole fraction of one component compound. Such a relation is expected from a virtual-crystal type of analysis.If E0m is the mean of the energy gaps of the component compounds of the system, it is found that an empirical relation of the form [Formula: see text] appears to hold where α is approximately 0.3 eV3/2.
THE V × B INTERACTION OF A SATELLITE WITH ITS ENVIRONMENT
Authors: Osbokne F. J. F. , Kasha M. A.
Published: April 2011

An earth satellite moving through the upper ionosphere interacts with the earth's magnetic field and the ambient plasma in such a way that a region of perturbed plasma, or "V × B" sheath, is formed around the vehicle. This paper analyzes the formation of such a plasma sheath, with particular reference to topside sounder satellites, and proposes a method for minimizing the adverse effects of such sheaths on the operation of the satellite or the experiments carried thereon.An account is given of the requirements necessary for the simulation in the laboratory of an earth satellite environment, at an altitude of approximately 1 000 km. The various diagnostic techniques used for the investigation of a simulated environment produced in a laboratory apparatus are described and the simulation conditions are shown to be satisfied.Experiments are described which are designed to test the theoretical model of the satellite in its environment, and specifically, to test the operation of the proposed technique for the elimination of the adverse effects of the V × B plasma sheaths formed around the instrumented body of a satellite carrying large antennas.
HEAT FLOW IN DIELECTRIC MATERIALS IN THE BOUNDARY-SCATTERING LIMIT
Authors: Matthews P. W.
Published: April 2011

The theory of Casimir (1938) for steady-state heat flow in the boundary-scattering limit for cylindrical samples is extended to include time-dependent effects. This shows that a term of the form (∂3T/∂x2∂t) is the first correction term which should be added to the usual thermal diffusion equation, the range of validity of the theory being restricted by the condition that the wavelength of the disturbance, [Formula: see text], where L is the mean free path of phonons in the bulk material and a is the radius of the cylinder. The dispersion relation is derived, and, as an example, dispersion curves are computed for liquid helium as the dielectric medium, contained in a tube of 1-cm radius. At high frequencies the velocity of the temperature wave is reduced below the value predicted by the diffusion equation.
THE ELECTRICAL RESISTIVITY OF THERMOMETRICALLY PURE PLATINUM BELOW 11 °K
Authors: Kos J. F. , Lamarche J. L. G.
Published: April 2011

A method is developed to obtain an interpolation of the resistance versus temperature function of pure platinum to an accuracy of about 0.01 °K in the range 4.2 to 10 °K, when calibration points below 4.2 and above 10 °K are available for a given sample. A study is made of the application of the two-band model to platinum in the range 1.5 to 11 °K. It is found that the accepted expressions for the ideal resistivity and for the Sondheimer–Wilson correction term do not describe the experimental results satisfactorily. Calculations of the ratio of the residual resistivity of band 2 to that of band 1, and of the ratio of the ideal resistivity of band 2 to that of band 1 indicate that electrons in the second band contribute significantly to the conductivity of platinum. A new expression for the ideal resistivity is proposed to account for the conductivity of the second bands
THERMALIZATION TIME OF POSITRONS IN METALS
Authors: Carbotte J. P. , Arora H. L.
Published: April 2011

The thermalization rate of positrons in metals is computed as a function of the electron density parameter r, for the entire range of metallic density 2 < rg < 5.7. The calculation is based on the propagator technique of many-body perturbation theory. In this formalism the rate of energy loss is essentially determined by the imaginary part of the positron self-energy operator which we treat both in the random phase approximation and the Hubbard approximation. In general, we find that the time required for the positron to drop to an energy of 0.025 eV is not as short as is commonly believed, although at room temperature there can be little doubt that complete thermalization has occurred. For aluminium at 100 °K, however, the thermalization time is longer than the annihilation time and it is suggested that this effect should be detectable in an experiment similar to Stewart and Shand's recent positron effective mass experiment in sodium.