bluuebunny/crossref_metadata_2025 huggingface dataset:
The vacuum ultraviolet spectrum of the bromine molecule
Authors: Venkateswarlu Putcha
Published: April 2011

The absorption spectrum of bromine has been photographed in the first and higher orders of a 10.7-m. concave vacuum grating spectrograph in the region 1700–1170 Å.A number of band systems have been obtained in the region 1510–1170 Å, most of which correspond to Rydberg transitions. In addition, an extensive band system with closely-spaced bands degraded to longer wavelengths has been recorded in the region 1700–1500 Å. Among the Rydberg systems, five series have been found to converge to 85 165 ± 80 cm−1 which represents the ionization potential of the molecule leading to the 2Π3/2g state of the molecular ion. They arise due to transitions from the ground state to [σg2πu4πg32Π3/2g]npσu, [σg2πu4πg32Π3/2g]npπu, [σg2πu4πg32Π3/2g]nfσu, [σg2πu4πg32Π3/2g]nfπu, and [σg2πu4πg32Π3/2g]nfδu configurations where n takes the running values 5, 6, 7, … etc. The first few members of four similar series corresponding to the transitions to the states involving the [σg2πu4πg32Π1/2g] core have been identified and the ionization limit of these series is estimated to be at 88 306 ± 80 cm−1. Two of the remaining band systems have been found to be very likely due to transitions to the Rydberg states with the configurations [σg2πu3πg42Π3/2u]5sσg and [σg2πu3πg42Π1/2u]5sσg, respectively. Three of the observed systems which do not involve Rydberg states appear to have for their upper levels the 1Πu(1u), 3Π(1u), and 3Π(0u+) states arising from the configuration σgπu3πg4σu2.
Ranges of nitrogen ions in Se and energy losses of alpha particles in Al, Ni, Se, Ag, and Au
Authors: Nakata Hiroshi
Published: April 2011

The range–energy relation of N in Se was obtained from an energy-loss curve in the energy region of 1–12 MeV. The results are slightly smaller than expected by theory. In view of medium dependence, selenium tends to differ from other media, and it has also been confirmed by energy-loss measurements of alpha particles.
Construction d'une base antisymétrique dans l'espace idéal
Authors: Simard P. A.
Published: April 2011

An antisymmetric basis has been set up in the ideal space as a combination of one boson and one ideal quasi-particle state; in this way a three quasi-particle system may be studied. The knowledge of solutions of linearized equations for two quasi-particles is a requisite for the setting up of this basis. The exclusion principle is thus introduced correctly. The spurious states coming from the non-conservation of the number of particles are separated out and can be rejected easily. The method can be used only in QTD approximation. The one-shell case is discussed as a verification of the method.
Studies of the ionic ferromagnet (LaPb)MnO3 I. Growth and characteristics of single crystals
Authors: Morrish A. H. , Evans B. J. , Eaton J. A. , Leung L. K.
Published: April 2011

Single crystals of La1−xPbxMnO3 with 0.25 < x < 0.45 have been grown by the flux technique. X-ray fluorescence, wet chemical, and electron microprobe analyses indicate the crystals are homogeneous and stoichiometric. The crystal structure was determined to be a rhombohedrally distorted perovskite with double cell edges.
Energy levels of Nd(IV) and Er(IV) in Y2O3
Authors: Narayana P. A.
Published: April 2011

The free-ion energy levels of Nd(IV) and Er(IV) in Y2O3 are expanded in a Taylor series, taking the effects of both linear and nonlinear configurational interactions into account. Numerical values of the partial derivatives of the energy levels with respect to F2, F4, F6, ξ, α, β, Y(22,1), and Y(22,3) are tabulated. The r.m.s. deviation in the case of Nd(IV) is improved from 90 cm−1 to 48 cm−1 and, in the case of Er(IV), the r.m.s. deviation is improved from 61.5 cm−1 to 43 cm−1. The improvements are the result of the inclusion of the extra parameters.
Comparison of reaction theories for multilevel interference—the 14C + p reactions
Authors: Tindle C. T. , Vogt E.
Published: April 2011

A comparison is made between the R-matrix and S-matrix theories of low-energy compound nucleus resonances for the particular case of two-level interference. The (p,γ) and (p,n) cross sections of 14C for proton energies between 0.7 and 1.5 MeV are analyzed using both theories. The 15N compound nucleus in this region exhibits strong two-level interference. The two theories provide equally good fits to the data, but the parameters describing the compound-nucleus levels are quite different. A general analytic method of relating the two sets of parameters is derived and shown to give good agreement with the results obtained by curve-fitting procedures. Remarks are made concerning the general behavior of the parameters under strong interference conditions and also on the inclusion of many channels into the analysis.
Spin–spin interaction in f5 electron configurations
Authors: Malli Gulzari , Saxena K. M. S.
Published: April 2011

The complete matrix of the spin–spin interaction for the f5 electron configuration is evaluated for general usage. The results of the diagonal matrix elements are tabulated here in terms of the corresponding spin–spin splitting factor for usage in the first-order perturbation calculations. These are used to evaluate the Hartree–Fock values of the splitting factors for Pm(4f5), Sm3+ (4f5), Tb(4f9), and Dy3+ (4f9).
Some observations of the sidelight and plasma impedance changes induced by a CO2 laser beam
Authors: Crane R. A.
Published: April 2011

The effect of 10.6 μ radiation, in CO2 laser plasmas, on the spontaneous emission at 2.4 μ and the plasma impedance is studied by a phase-lock technique. The results reveal the influence that collisions between molecules in the primary laser cycle and excited states have on the properties of the discharge.
The field induced in a two-layer conductor by a magnetic dipole
Authors: Weaver J. T. , Thomson D. J.
Published: April 2011

The integral solutions giving the electromagnetic field induced within the upper layer of a two-layer conductor by a vertical magnetic dipole are evaluated using an asymptotic expansion suggested by Wait. The method is shown to be applicable when the height of the dipole is a large number of "upper-layer skin depths" above the surface of the conductor, and an expression is derived which gives an estimate of the error involved in retaining only the first term of the expansion. The results are presented in a dimensionless form which depends only on the ratio of the conductivities in the layers. Graphs depicting the variation of the field components within the upper layer of the conductor are plotted for the special case of seawater over dry rock, a situation of practical importance when submerged recording instruments are used to measure geomagnetic field variations at sea. The curves show that a layer of seawater has a strong screening effect on the horizontal magnetic component, but that the vertical magnetic and electric components undergo only a slight attenuation beneath the sea.
Calculation of some thermomagnetic coefficients in degenerate semiconductors for mixed scattering by acoustical phonons and ionized impurities
Authors: Kužel R. , Sharma S.
Published: April 2011

In this paper, the authors have calculated the variation of the transverse Nernst–Ettingshausen coefficient, the transverse Righi–Leduc coefficient, and the Ettingshausen coefficient with impurity parameter. The influence of adiabatic thermomagnetic effects on the Hall and Nernst–Ettingshausen coefficients has also been studied. It has been shown that a correction term due to adiabatic effects can reach considerable values especially for the Nernst–Ettingshausen coefficient.
Electrical characteristics of ion implanted boron layers in silicon
Authors: Shannon J. M. , Tree R. , Gard G. A.
Published: April 2011

Sheet resistance and Hall measurements have been made on boron layers implanted into [Formula: see text] and [Formula: see text] silicon at energies between 15 and 60 KeV. The features of the annealing curves are discussed. Hall measurements indicate that the large reverse annealing effect observed in several samples implanted at room temperature is due to a rapid fall off in the density of an acceptor level between annealing temperatures of 400 and 600 °C. It is suggested that this level is associated with substitutional boron.Conducting layers formed by implants at high doses (6 × 1015 cm−2) and low annealing temperatures are shown to be sensitive to specimen temperature during implantation and dose rate. This sensitivity is associated with the formation of an amorphous layer.The conductivity of layers implanted at temperatures of 400–500 °C is shown to be lower than corresponding room temperature implants followed by annealing.
Regions of validity for Debye and inverse third-power models for shielding of test charges
Authors: James C. R. , Vermeulen F.
Published: April 2011

The shielding potential for a test charge in a plasma is derived for the case in which the velocity of the charge is much less than the thermal velocity. This potential is an analytical expression valid for any angle in space. The potential contains the Debye term and also a term which is due to the particle's motion. At large distances from the test charge the latter term asymptotically becomes proportional to the inverse third power of the distance. On the other hand, as the distance to the test charge approaches zero, this term vanishes and the potential becomes the Coulomb potential. It is shown that, although the inverse third-power term dominates at very large distances, the Debye term dominates over the very important region out to at least several Debye lengths.
Passive element high power transmitters
Authors: Litva J. , Fulford J. A.
Published: April 2011

Landecker and Imrie describe a high power pulse transmitter of novel design using a simple radiating mechanism. A prototype, following their design, has been constructed at this laboratory. This note describes the triggering process and suggests a possible method of overcoming the difficulty of obtaining uniform triggering necessary for the transmitter to operate as designed.
De Haas–Van Alphen frequency variations and curvature of the Fermi surface
Authors: Perz John M.
Published: April 2011

The angular variation of the extremal cross-sectional area of a surface formed by revolving an arc of a circle about an axis has been calculated for various ratios of arc radius to radius of revolution. By comparing with these results experimental rotation diagrams for portions of Fermi surfaces of metals which are approximately surfaces of revolution, values of local radii of curvature averaged over an extremal orbit can be deduced.
Conduction bands of GaxIn1−xAs and InAsxSb1−xalloys
Authors: Coderre William M. , Woolley John C.
Published: April 2011

Measurements of Hall coefficient and electrical conductivity have been made on alloys of the systems GaxIn1−xAs and InAsxSb1−xover a range of temperature from 200 up to 950 °K or to 20° below the solidus temperature of the particular specimen, whichever was lower. These data have then been analyzed in terms of equations involving all the occupied conduction and valence bands in the manner described previously by Coderre and Woolley. The results give the variation of the energy separation from the valence band of the (000) conduction-band minimum as a function of the composition and temperature for both alloy systems. For a certain range of x in the InAsxSb1−x alloys, a transition to the gray-tin band structure is observed at high temperatures.
23Na quadrupole relaxation in sodium nitrate using double resonance
Authors: Hughes D. G. , Reed K. , Snyder R. E.
Published: April 2011

The 23Na spin system in a single crystal of NaNO3 at room temperature has been studied using a double-resonance method. The ratio of the quadrupole relaxation probabilities W2/W1 is found to be 0.963 ± 0.012 at θ = 0°.
Ionospheric propagation experiments using rockets and satellites
Authors: Palmer F. H. , Doan J. W. , Forsyth P. A.
Published: April 2011

Rocket-borne and satellite-borne radio transmitters have been used to investigate ionospheric irregularities. The amplitude, phase, and polarization of the radio waves as received on the ground can provide important information about the spatial gradients of ionization through which the waves have travelled. In particular it has been possible to derive quite detailed ionization profiles by two independent methods; angle-of-arrival and Faraday rotation measurements. The good agreement obtained between the two methods for a certain range of scale sizes where both methods are valid suggests that outside this range where one or other method is to be preferred, it can be used with confidence.
Photosensitive tunneling in superconductivity
Authors: Radhakrishnan V.
Published: April 2011

Theoretical treatment of the model proposed by Giaever for his experiment on the photosensitive tunneling in superconductors is examined. New relations are derived which connect the photoconductive property of the barrier and the tunneling current. These relations are helpful to check the model and to determine the density of states for the trapped holes at the hole Fermi level.
Approach to steady state for stimulated thermal Rayleigh scattering
Authors: Enns R. H.
Published: April 2011

In this paper we derive a theoretical expression for the backscattered stimulated thermal Rayleigh scattering intensity which is valid for all times and all gains. In the appropriate limit our result reduces to that reported by Rother et al. Some implications for future transient experiments are discussed.
Interferometric measurement of line widths and frequencies of the S0(0) and S0(l) rotational Raman lines of H2
Authors: Cooper V. G. , May A. D. , Gupta B. K.
Published: April 2011

The line shape and change in frequency of the line center have been accurately determined for the S0(0) and S0(1) rotational Raman lines of normal H2 at densities from 2 to 38 amagat, and for the S0(1) line for mixtures of normal H2 in helium and argon at total densities from 7 to 85 amagat. For pure H2 the absolute Raman displacement extrapolated to zero gas density was also measured for both rotational lines. The accuracy obtained, ± 0.002 cm−1, results from the application of interferometric techniques to Raman spectroscopy and represents about an order of magnitude improvement over earlier measurements.
A spectroscopic determination of the nuclear moments of bismuth
Authors: Crooker A. M. , Shipley George
Published: April 2011

The nuclear magnetic moment μ, and the electrostatic quadrupole moment Q, were obtained from the spectra of Bi II, III, and IV. μ, derived from the one-electron hyperfine structures of Bi III, was 4.23(0.10) nuclear magnetons. μ, derived from hyperfine structures of sl configurations of Bi II and Bi IV, was 3.7(0.5) nm. Q, derived from sl configurations of Bi II, was −0.4(0.1) b; hyperfine structures of Bi IV yield values from 0.79 to −20 b. Three new "A" factors for Bi II are also presented.
Appraisal of near-field solutions for a Hertzian dipole over a conducting half-space
Authors: Chang David C. , Wait James R.
Published: April 2011

Various approximations to the exact formal integral representations of the near-field and the impedance are considered. A new approximate form is obtained which appears to be valid even when the dipole is near a poorly conducting earth. Numerical comparisons with the exact integral formula verify some of the conjectures. The result shows that the ground has a significant influence on the input impedance of the dipole, particularly for low heights.
Remarks on the modulation of low-rigidity particles in cosmic radiation
Authors: Sandor T.
Published: April 2011

The flux of low-energy positrons of radioactive origin in cosmic radiation has been estimated from collisions of the B, C, N, O, Na, Mg, Tr, Cr, Fe, Ni, Co, and Cu nuclei with protons of interstellar matter. The estimations are not compatible with a residual solar modulation of the form exp (−η/Rβ) (where η, R, and β are the modulation parameter, rigidity, and velocity, respectively) for the values of R smaller than ~0.3 BV.
Weakly ionized field-free plasmas enclosed in emitting surfaces
Authors: Ekbote D. D. , Schott L. , Whitfield D. W. A.
Published: April 2011

Calculations are presented for the spatial charge-density distribution in a stationary, weakly ionized, low-pressure plasma which is enclosed in plasma-emitting surfaces. Solutions are given for the cases that the emitting boundaries are two infinite parallel planes, an infinite cylinder, a sphere, and a cylinder of finite length with absorbing end faces. The theoretical results for the finite cylinder are compared with experimental data on helium, argon, and nitrogen at pressures between 0.1 and 0.5 Torr using a new plasma source. The plasma is produced by a discharge in a region between two concentric cylinders; the inner one, the anode, is perforated and a quiescent diffusion-plasma free of electric fields and electric currents is formed in its interior with densities between 108 and 1011 cm−3 and electron temperatures of 0.3 to 0.5 eV. Qualitative agreement between the observed and calculated density distributions has been found in certain cases.
Effect of the change of electrostatic constraints on the phase transitions of some phenomenological models of ferroelectrics
Authors: Huang C. C. , Grindlay J.
Published: April 2011

The effects of changes of electrostatic constraints on the ferroelectric phase transition are described. The discussion is based on a system consisting of a parallel-plate condenser with a dielectric slab insert. The material of the slab is assumed to be a ferroelectric with an equation of state, in the direction normal to the plates, of the form E = A(θ − θ0)D + ξD3 + ζD5. As the plate separation of the condenser is changed, the nature of the phase transition may change. The results are presented in the form of phase diagrams.
Calculation of the magnetostriction and thermal expansion of an itinerant-electron ferromagnet
Authors: Meincke P. P. M.
Published: April 2011

The magnetostriction and thermal expansion of a Stoner itinerant-electron ferromagnet are calculated with the aid of the grand partition function. It is shown that the volume distortion is proportional to the square of the magnetization and that the magnetostriction and thermal expansion can be thought of as arising from changes in the magnetization brought about by changes in magnetic field and temperature.
Lifetime of the 77 keV level in 32P
Authors: Boulter J. F. , Prestwich W. V.
Published: April 2011

A delayed coincidence measurement of the half-life of the 77 keV level in 32P populated by the 31P(n,γ)32P reaction has been performed. The results obtained using slope, third moment, and two centroid shift analysis procedures are presented, and the mean value of 10 runs performed under different experimental conditions is T1/2 = 253 ± 25 ps.
An improved optical resonator for measuring time-dependent electron densities
Authors: Curzon F. L. , Funk L. W.
Published: April 2011

The performance of an optical resonator used for measuring time-dependent electron densities in the collapse phase of a Z pinch has been improved by the introduction of a simulated concentric mirror system, which reduces problems due to gradients in the refractive index inherent in the nonconcentric configuration, and by the introduction of a rotating quartz block, which modulates the resonator length, increasing the temporal resolution by a method analogous to the fractional-fringe techniques of conventional interferometry.
Cross sections for the scattering of massless particles by graviton exchange
Authors: Peet F. G.
Published: April 2011

The gravitational scattering of various types of massless particles is considered. Cross sections are given for the gravitational scattering of scalar particles by: scalar particles, photons, four component neutrinos, and two component neutrinos; of photons by: photons, four component neutrinos, and two component neutrinos; of four component neutrinos by four component neutrinos; and of two component neutrinos by two component neutrinos. The cross section given by Barker et al. and by Boccaletti et al. for the scattering of photons by photons is confirmed. The cross section for the scattering of scalar particles by scalar particles given by DeWitt and the cross section for the scattering of photons by scalar particles given by Boccaletti et al. are found to be in error.
Laser-induced dielectric breakdown and mechanical damage in silicate glasses
Authors: Sharma Bhim S. , Rieckhoff Klaus E.
Published: April 2011

Dielectric breakdown and mechanical damage in silicate glasses under high-intensity laser radiation are investigated in detail. From thermoelastic considerations a criterion for the validity of possible damage mechanisms is established. It is shown that stimulated Brillouin scattering cannot give rise to an effective absorption of 50 cm−1 in the focal volume as required by the thermoelastic considerations. It is proposed and established that the mechanical damage is caused by the acceleration of primary electrons produced by multiphoton ionization, leading to a fully developed instability in a few nanoseconds. At this electron density, the absorption in the focal volume is 105 cm−1, and is responsible for the complete absorption of the laser pulse at intensities above the threshold for breakdown. The diffusion and recombination of electrons are found to be negligible, the only rate-limiting process being the loss of electron energy to the lattice. The variation in the threshold intensity for breakdown in different glasses is due to the variations in the elastic scattering cross section.
Spectrum of the CN molecule. I. Absorption in the vacuum ultraviolet
Authors: Lutz Barry L.
Published: April 2011

The vacuum ultraviolet absorption spectrum of CN is observed for the first time revealing a weak band system between 1490 and 1820 Å. Rotational and vibrational analysis shows the upper state to be the known E2Σ+ state. Four new vibrational levels are reported, resulting in the following molecular constants for the E state (cm−1):[Formula: see text]The strength of the absorption and its significance in astrophysics is discussed. The dissociation limits and the electron configurations of all known electronic states of CN are also discussed, and a tentative assignment of a previously unassigned 2Π state is proposed.
Far-infrared absorption in bulk samples of superconducting niobium and tantalum
Authors: Hemming D. , Sati R. , Leslie J. D.
Published: April 2011

Measurements have been made of far-infrared absorption in bulk samples of superconducting niobium and tantalum at 1.41 °K. The results indicate a gap width 2Δ of 23.8 ± 0.2 cm−1 for niobium and 10.3 ± 0.2 cm−1 for tantalum. The measured values of the critical temperature, Tc, for these samples are 9.38 ± 0.04 °K for niobium and 4.33 ± 0.02 °K for tantalum. In terms of these values of Tc, 2Δ is 3.66 ± 0.05 kTc for niobium and 3.43 ± 0.08 kTc for tantalum. These values of 2Δ are in good agreement with those obtained by other methods, unlike earlier far-infrared absorption measurements on bulk niobium and tantalum that indicated anomalously low values of 2Δ.
Annihilation of positrons in helium, neon, and argon
Authors: Montgomery R. E. , LaBahn R. W.
Published: April 2011

The electric field dependences of the direct annihilation rates for positrons in helium, neon, and argon are calculated. This is done by using a systematic description of the scattering process. The momentum transfer and direct annihilation cross sections are calculated within the framework of the polarized-orbital method which has worked well for electron–atom scattering. The cross sections are then used in the appropriate diffusion equation to determine the experimentally observable annihilation rates appropriate to the exponential decay region of the spectrum. The resulting annihilation rates are found to be extremely sensitive to the low-energy behavior of the cross sections. Best agreement between calculated and experimental annihilation rates is obtained for helium where fairly rigorous calculations of the cross sections are available. Good agreement between theory and experiment for neon and argon is obtained only by making judicious choices for the components of the distortion included in the calculations. It is thus concluded that the positron–atom scattering process is considerably more sensitive to the details of the mutual distortion interaction than is observed in the corresponding electron–atom collision process.
Latitude variation of radar aurora with local substorm activity
Authors: Harris F. R. , Kavadas A.
Published: April 2011

Radio aurora detected at Prince Albert advances farther south with increasing magnetic activity. The latitude vs. magnetic activity relation for radio aurora is compared with similar relations for ionospheric currents. The effect of aspect sensitivity is discussed.
Quadrupole interaction of 181Ta in HfO2
Authors: Gardner P. R. , Prestwich W. V.
Published: April 2011

Studies are presented of the static quadrupole interaction of the 482 keV level of 181Ta in a polycrystalline HfO2 source, made using a differential perturbed angular correlation (PAC) method. The experimental procedure and method of analysis are described and the results obtained for the following interaction parameters are: the transition frequencies ω0 = 819 ± 10, ω1 ± 1483 ± 25, ω2 = 2350 ± 50 Mrad/s, the quadrupole interaction frequency ωQ = 125.8 ± 1.9 Mrad/s, the asymmetry parameter η = 0.283 ± 0.027, and the electric field gradient at active lattice sites Vzz = 13.1 ± 0.6 × 1017 V/cm2. These results are compared with those recently obtained by other workers in this field.
Electron spin resonance studies of Cr3+ impurities in soda alum
Authors: Manoogian A. , Danilov A. G.
Published: April 2011

The electron spin resonance of Cr3+ impurities was studied in two types of crystals which grew out of a saturated solution containing a mixture of sodium sulfate, aluminum sulfate, and chromium sulfate dopant. One of the crystals was identified as soda alum, NaAl(SO4)2∙12H2O, which has cubic symmetry, while the other was a monoclinic crystal of undetermined structure. In soda alum, four differently oriented, but otherwise equivalent, magnetic complexes of chromium were found. Each complex exhibited an axial distortion along one of the crystal body diagonals. In the monoclinic crystal, two differently oriented, but otherwise equivalent, magnetic complexes of chromium were found. Each of the complexes exhibited a strong rhombic distortion but none of the magnetic axes coincided with the crystallographic axes. However, the complexes were related by twofold symmetry to the monoclinic b axis. The ESR results of the two crystals were fitted to suitable spin Hamiltonians and the pertinent parameters were determined. The crystallographic parameters (a, b, c) of the monoclinic crystal were determined by X-ray analysis.
Thermal conductivity and electrical resistivity of pure silver between 80 and 350 K
Authors: Matsumura T. , Laubitz M. J.
Published: April 2011

We report the results of precise determinations of the thermal conductivity and electrical resistivity of high purity silver in the temperature range 80 to 350 K. At the higher temperature end, our results are in excellent agreement with those previously reported by Laubitz, while at the lowe end our values agree very well with the values given by White and Woods. The ideal Wiedemann–Franz ratio, computed from the results of the latter and from our own, shows a dip in the range 60 to 80 K, which is not observed in either copper or gold.
On threshold resonances
Authors: Tindle C. T.
Published: April 2011

A comparison is made of the way R-matrix and S-matrix theories analyze the threshold resonances which occur in the scattering of neutral particles by a square well. Both approaches are found to provide very good approximate formulas. However, modifications of the usual S-matrix expansions must first be made. The behavior of the energy of the threshold level is quite different in the two alternatives. By comparing the two theories in their interpretation of the low-energy neutron cross sections of 1H, 16O, and 208Pb it is concluded that.R-matrix theory provides a better interpretation for unbound levels and S-matrix theory is preferable when the threshold level is bound.
Lattice frequency spectra of Pb and Pb40Tl60 by neutron spectrometry
Authors: Roy A. P. , Brockhouse B. N.
Published: April 2011

Lattice frequency spectra of Pb and Pb40Tl60 have been measured at 90 °K by inelastic coherent scattering of slow neutrons from a polycrystalline specimen. The results compare favorably with the tunneling measurements of Rowell, McMillan, and Feldman. In Pb40Tl60 we see direct evidence of energy smearing arising from the finite lifetimes of the phonons caused by force-constant disorder in the alloy.
Electromagnetic fields in the presence of cylindrical objects of arbitrary physical properties and cross sections
Authors: Shafai L.
Published: April 2011

Approximate solutions for two-dimensional problems of electromagnetic fields in the presence of cylindrical objects have been found by approximate evaluation of a scattering matrix. The equations are derived for cylindrical objects of arbitrary physical properties and cross sections and a procedure for evaluation of the matrix elements is discussed. The elements of permittivity and permeability tensors are assumed to be analytic, but otherwise arbitrary functions of the transverse coordinates.
Duration of energy storage following a discharge in xenon
Authors: Timpson P. R. , Anderson J. M.
Published: April 2011

It has been shown that the afterglow following a discharge in xenon consists of two parts: (1) the resonance line, whose intensity initially decays exponentially in agreement with Holstein's theory; (2) an accompanying distributed radiation, experimentally a continuum, extending to about 1900 a.u. The intensity of this continuum decays exponentially at the same rate as the population of the lower metastable state at all wavelengths and each pressure studied. All departures from an exponential decay seem to be caused by repopulation of states by ionic recombination and are current dependent. Electron disappearance is due to ambipolar diffusion at low pressures and ion recombination at high pressures. The value of the ambipolar diffusion coefficient indicates that the afterglow positive ion is Xe2+ for pressures greater than 0.3 Torr. No phenomena which could be due to interchange of population between metastable states have been found in xenon.
Backscattering of light atomic projectiles from thin Au films in the energy range 50–110 keV
Authors: Wijngaarden A. van , Brimner E. J. , Baylis W. E.
Published: April 2011

Thin gold films, vacuum deposited onto a beryllium substrate, have been irradiated by projectiles of 1H, 4He, 7Li, and 11B in the energy range 50–110 keV and the backscatter intensity measured at a laboratory scattering angle of 136.4°. An analytic expression for the scattering cross section in a shell-shielded Coulomb potential has been derived and is found to be in good agreement with the present experimental results. For thin films the observed backscatter yield is not proportional to the film thickness, but increases more rapidly. The enhancement in the yield can be explained by small-angle multiple deflections. It has been corrected for, using estimates for the angular divergence of a beam passing through a thin stopping region.
Veneziano model and the finite energy sum rules
Authors: Vasavada Kashyap V.
Published: April 2011

We sum explicitly the left-hand side of the finite energy sum rules for the Veneziano amplitude. This shows that, for sufficiently large cutoff, the finite energy sum rules are satisfied with the leading contribution only. The actual sum contains other non-leading contributions.
On the uniqueness of the quadratic action Lagrangian in general relativity
Authors: Gogala Borut
Published: April 2011

A procedure, suitable for translation into computer language and analogous to the uniqueness proof of Einstein's field equations in vierbein formulation, is developed for finding the most general quadratic action Lagrangian density in general relativity that satisfies the requirement of covariance and of invariance under coordinate dependent frame reorientation. It is found that this Lagrangian is identical with the most general linear combination that can be made up out of the three scalars formed by bilinear combinations of the Riemann curvature tensor.
Dipole polarizability of the hydrogen molecule: a single-center calculation
Authors: Cohen M. , Southern B. W.
Published: April 2011

The leading terms in a single-center expansion of the static dipole polarizability tensor of the hydrogen molecule has been calculated by means of perturbation theory.
Directional correlations of gamma rays in 152Sm and 152Gd measured by means of two Ge(Li) counters
Authors: Barrette J. , Barrette M. , Boutard A. , Lamoureux G. , Monaro S.
Published: April 2011

Directional correlation measurements have been performed with two Ge(Li) counters on several γ rays in coincidence with the 121.78 and 334.31 keV γ transitions which de-excite the first 2+ levels in 152Sm and 152Gd, respectively. A total of 20 γ−γ directional correlations, 13 in the 152Sm nucleus and 7 in the 152Gd nucleus, was measured simultaneously. Several of the γ−γ directional correlations involved gamma transitions of weak intensity, for example the (688.66−121.78), (1457.4−121.78), and (1528.16−121.78) keV cascades in 152Sm and the (586.29−334.31) and (1089.73−334.31) keV cascades in 152Gd. Among the various results which could be extracted from these measurements, the most interesting appears to be the determination of a nearly pure E2 character for the 688.66, 964.01, 1112.04, and 867.33 keV gamma transitions. The first two γ rays de-excite the 2+ β- and γ-vibrational levels to the 2+ ground-state rotational level at 121.78 keV in 152Sm, whereas the last two γ rays de-excite the3+ γ-vibrational level to the 2+ and 4+ (at 366.44 keV) ground-state rotational levels in 152Sm.
Lattice dynamical effects in the frequency analysis of the infrared and Raman spectra of solid parahydrogen
Authors: Noolandi J.
Published: April 2011

The frequency perturbations of the rotation–vibration levels in solid H2, due to the modulation of the anisotropic and vibrational intermolecular interaction by the lattice vibrations, are calculated. The lattice vibrations are treated in the self-consistent harmonic (SCH) approximation with short-range correlations, and the intermolecular interaction is expanded in terms of the quantum crystal phonon operators. The discrepancy between previous calculations of the effective quadrupolar coupling constant and the experimental values is resolved when the roton–phonon interaction is properly renormalized to take into account the long-range phonon correlations. The energy of the induced dipoles in the quadrupolar field of all the H2 molecules in the crystal (dielectric screening energy) is considered, and in particular the effect of this induction energy on the roton band energies is calculated. The frequencies of the infrared and Raman S0(0) lines are analyzed, taking into account the frequency shifts due to the roton–phonon interaction and the dielectric screening energy, and a value of the effective quadrupolar coupling constant which is consistent with other experimental values is derived. New values of the crystalline field constants ε2C and ε4C are given. The shift and splitting of the S1(0) Raman line is recalculated, taking into account the interaction with the lattice vibrations, and the splitting of the S1(0) + S1(0) doublet in the overtone infrared spectrum is calculated using a different perturbation scheme from the previous calculations. The limitations on the frequency analysis due to the uncertainty in the roton–phonon coupling parameters are discussed.
Decay of 90Kr and 90Rb
Authors: Mason J. F. , Johns M. W.
Published: April 2011

The decay of 32 s 90Kr and 154 s 90Rb has been studied using NE102 beta detectors and NaI(Tl) and Ge(Li) gamma-ray detectors, singly and in coincidence. Thirteen excited states of 90Rb involving 35 transitions have been identified with excitation energies of 0.1064, 0.1215, 0.2419, 0.3557, 0.6144, 0.6610, 0.7408, 0.8375, 1.2402, 1.6740(1+), 1.7798(1+), 2.1261(1+), and 3.0937(1+) MeV. The 256 s isomeric state at an excitation of 0.1064 MeV (probably 4–) feeds high spin states of 90Sr at 2.2068, 2.4972, 2.5712, 2.9275, 3.5835, 4.1485, 4.3355, and 5.0397 MeV with a total intensity of 12%. The 154 s ground state of 90Rb feeds many low spin states in 90Sr, including the levels at 0.8315, 1.6555, 1.8921, 2.5271, 3.0385, 3.3833, 3.4497, 3.8985, 4.0325, 4.0360, 4.1360, 4.3660, 4.6466, 4.891, 4.921, 4.974, 5.070, 5.091, 5.163, 5.1876, 5.2540, 5.285, and 5.3336 MeV. Sixty-four transitions in 90Sr have been classified in this manner. The decay energy of 90Kr is 4.41 ± 0.03 MeV.
Visible emission bands of molecular oxygen
Authors: Findlay F. D.
Published: April 2011

Emission bands at 4784, 5165, and 5788 Å have been observed in the afterglow of an electrical discharge through oxygen. From a comparison with liquid-oxygen spectra these bands have been assigned to double electronic transitions involving the 1Δg and 1Σg+ excited states of oxygen. The relative intensities of these bands have been measured under conditions where the concentrations of these excited species were varied by three different methods. The results support the original assignment of these bands.
Nonlinear frequency shift in whistler and hydrodynamic propagation
Authors: Frey Jean-Pierre , Roux Alain
Published: April 2011

Nonlinear effects for the electronic and ionic cyclotron modes propagating in the magnetosphere are studied by using the Vlasov equation; the frequency shift is deduced to the third order.Going to the case of a cold plasma for the whistler mode, we find that frequency shift vanishes, a result in agreement with Tidman and Stainer, based on the moments equations, but in contradiction with Watanabe's results derived from the Vlasov equation.For the hydromagnetic waves the effect does exist, but is not sufficient to explain the frequency–time displays ("sonagrams") of the so-called "pearl" events.
Molecular orbital approach to the spectra of the Co2+ ion in tetrahedral crystals with axial distortion
Authors: Jugessur S. , Savard J.-Y. , Rai R.
Published: April 2011

The semi-empirical LCAO–MO method has been utilized to study the electronic spectra of the Co2+ ion embedded in host crystals of CdS, ZnS, and ZnO. The crystals are assumed to have an axial distortion, thereby changing the Td symmetry to C3v. One-electron energy levels and state vectors are evaluated by the MO method. The results are used to analyze the fine structure of the optical bands of the Co2+ ion in those environments, and to calculate the anisotropic [Formula: see text] and [Formula: see text] and the zero-field splitting D. It is found that the molecular orbitals are good basis functions and that the spin–orbit coupling constant λ, less than the free ion value, is required for a proper assignment of the fine-structure bands.
Realizations of chiral transformations: explicit forms
Authors: Charap John M.
Published: April 2011

The parallel approaches to the general problem of giving nonlinear realizations of chiral SU(n) [Formula: see text]SU(n) appropriate to phenomenological field theories as derived by Callan, Coleman, Wess, and Zumino on the one hand, and by Barnes and Isham on the other, are reviewed and compared. Explicit expressions are given for the nonlinear functions of the pseudoscalar meson field variables which arise in these methods.
Calculation of the vibration spectra of isotopic alloys using the Green's functions method
Authors: Klvaňa F.
Published: April 2011

Three methods are developed for the calculation of the inverse Green's function of alloys. One is a perturbation method using an expansion in powers of the concentration; the other two are nonperturbational and one of these is self-consistent. Methods are developed for lattices with both short- and long-range ordering.
Use of single planar Ge(Li) detectors as gamma-ray polarimeters
Authors: Litherland A. E. , Ewan G. T. , Lam S. T.
Published: April 2011

The polarization sensitivity of a single rectangular Ge(Li) detector 40 × 25 × 3.5 mm has been studied as a function of energy using gamma rays of known linear polarization produced in (p,p′γ) reactions. The counting rates in the total absorption peaks were measured with the 40 × 25 mm face perpendicular [Formula: see text] and parallel [Formula: see text] to the plane defined by the ion beam and gamma-ray direction. The asymmetry ratio [Formula: see text] was measured using E2 gamma rays with known polarization. From these results the following values of Q for complete polarization were deduced for a series of energies: 0.847 MeV (16.4 ± 1.0)%, 1.368 MeV (13.1 ± 1.0)%, 1.779 MeV (12.4 ± 1.5)%, and 4.43 MeV (6.4 ± 1.0)%. These results were in quantitative agreement with calculations made using the Klein–Nishina formula. A large volume detector 60 × 35 × 6.5 mm was studied in a similar manner. The corresponding results for complete polarization are: 0.847 MeV (16.4 ± 1.0)%, 1.368 MeV (14.3 ± 2.0)%, 1.779 MeV (11.6 ± 1.2)%, and 4.43 MeV (5.8 ± 1.5)%. These values are slightly higher than those obtained in calculations. Tests were also made with a lead collimator 6.25 cm long with an aperture of 1 cm in front of the larger polarimeter. The results for complete polarization are: 1.779 MeV (14.0 ± 1.5)% and 4.43 MeV (9.0 ± 1.0)%. Some recent applications of high-resolution Ge(Li) linear polarimeters are briefly discussed.
Sum rules and symmetries
Authors: Gunson J. Russell
Published: April 2011

The results of saturating sum rules are shown to be the same as those obtained by Fulco and Wong in their bootstrap model. It is also shown how these models tie in with the intermediate coupling theory of Kuriyan and Sudarshan, which explains why higher symmetry results are obtained from these models. We then demonstrate how certain amplitudes correspond to specific t-channel spin, in the p-wave limit. Because of this, spin-symmetric results are obtained. Finally we present a soluble model in which the mass of the isobars is linear in isospin.
On a duality invariant action principle in vacuum electrodynamics
Authors: Levman G. M.
Published: April 2011

Although Maxwell's vacuum field equations are invariant under the so-called duality rotation, the usual Lagrangian density for the electromagnetic field, which is bilinear in the first derivatives of the electromagnetic potentials, does not exhibit that invariance. It is shown that if one takes the components of the electromagnetic field tensor as field variables then the most general Lorentz invariant Lagrangian density bilinear in the electromagnetic fields and their first derivatives is determined uniquely by the requirement of duality invariance. The ensuing field equations are identical with the iterated Maxwell equations.
Amorphous substances and liquids—the existence of energy gaps in their one-dimensional analogs
Authors: Leung M. L. C. , Tong B. Y.
Published: April 2011

The model of a one-dimensional liquid or amorphous material is represented by a linear chain of symmetric, localized, but otherwise arbitrary, potential cells, each of which consists of a central core, the same in all cells, surrounded by two regions of zero potential of varying extent. The physical restriction that cell sizes are bounded is applied. The present article gives the proof for the existence of gaps in such a model. It is also hinted that the proof can be generalized to the real situation where the central core potentials may be slightly different from one another.
Auroral ionization and incident magnetospheric electrons
Authors: Catchpoole J. R.
Published: April 2011

A model is studied in which the supply of energetic electrons from a spiralling magnetospheric path to auroral atmospheric heights is considered. In particular, a calculation is made of the effect on atmospheric penetration which might be expected as a result of the combined influence of two magnetospheric accelerating mechanisms: (a) magnetic line convergence and (b) the superposition of a parallel electric field. This determination depends on details of energy and pitch angle distributions for precipitated electrons, and is made with reference to an isotropic distribution in the equatorial plane. Results indicate the significant control by magnetospheric electric fields on auroral ionization.
Table of EO conversion probability electronic factors
Authors: Bell D. A. , Aveledo C. E. , Davidson M. G. , Davidson J. P.
Published: April 2011

This paper presents, in tabular form, the electronic factor of the electric monopole conversion probability as a function of the atomic charge number Z and transition energy k for K, LI, and LII shells. The table lists factors over a range of k/mc2 from 0.1 to 5.0 units in increments of 0.1 units and from Z = 40 to Z = 102 in steps of ΔZ = 2. The factors are calculated relativistically and include corrections for finite nuclear size and bound state atomic screening.
Microwave scattering from dielectric structures
Authors: Sen K. , Fedotowsky A. , Rouillard M.
Published: April 2011

This paper deals with the scattering of plane electromagnetic waves of arbitrary polarization and angle of incidence by inhomogeneous dielectric structures. A theoretical model for such scattering is developed. Also presented is the description of an experimental facility using microwaves and the comparison of measured scattering patterns with calculations using exact solutions and proposed approximate formulations.
Hole mobility in Cu2O.I. Scattering by lattice vibrations
Authors: Kužel R. , Weichman F. L.
Published: April 2011

The hole mobility in Cu2O was measured using guard ring and Hall current techniques over a temperature range of +200 to −125 °C. For samples with highest mobility the temperature dependence was found to be approximately exponential with different activation energy above and below +60 °C. The results are explained on the basis of the known vibrational spectrum of Cu2O with polar scattering by an optical phonon of 0.0795 eV and nonpolar scattering by optical phonons of 0.139, 0.023, and 0.0185 eV predominating. Variations in mobility due to changes in dielectric constant are also discussed.
Magnetic resonance and quadrupole coupling in vanadium–oxygen compounds
Authors: Segel S. L. , Creel R. B.
Published: April 2011

51V nuclear magnetic resonance has been observed in M(VO3) where M = Li, Na, K, Cs, Ba, and Ca. Vanadium magnetic resonance has also been observed in Na3VO4, KVO31H2O, and KVO3–glass. The 23Na has been observed in the sodium salts and 7Li in LiVO3. A graphical technique has been developed which allows the determination of the quadrupole coupling, the asymmetry parameter in the electric field gradient, and the chemical shift parameters and avoids the necessity of computer fits to the line shape. A simple model, using only nearest-neighbor interactions, is successful in illustrating the sensitive dependence of the asymmetry parameter on crystal structure parameters.
Directional correlations of gamma-ray cascades in 103Rh
Authors: George M. C. , Mukerji Ambuj
Published: April 2011

The directional correlations of the 557–53-keV and the 444–53-keV gamma-ray cascades observed in the decay of 103Ru have been studied. Dilute liquid sources (RuCl2 in HCl) of varying activity and of predetermined correlation times τc were used. The unperturbed angular correlation functions were evaluated to be:[Formula: see text]Spins and parities of the 650- and 537-keV levels of 103Rh deduced from the analysis of the experimental data and consistent with the restriction of the 53-keV gamma as an M1 transition, indicated by internal conversion coefficient results, are discussed.
Hyperfine field at 181Ta nuclei in a nickel lattice
Authors: Cameron J. A. , Gardner P. R. , Prestwich W. V. , Zamori Z. , Santry D. C.
Published: April 2011

The value of the hyperfine field on Ta nuclei implanted in a nickel lattice was determined at room temperature by time-differential perturbed angular correlation measurements both with and without an external polarizing magnetic field. The value is −89.9 ± 1.0 kG.