bluuebunny/crossref_metadata_2025 huggingface dataset:
THE QUANTUM MECHANICAL CALCULATION OF THE SURFACE ENERGY OF SODIUM CHLORIDE— A FIRST APPROXIMATION
Authors: Benson G. C. , Zeggeren F. Van
Published: April 2011

Löwdin's theory for the cohesive energy of alkali halides has been used to calculate a first approximation to the surface energy of a {100} face of sodium chloride. The value found, 187 ergs/cm.2, differs from the experimental value determined by measuring heats of solution (276 ergs/cm.2) but is about 18% higher than the figure obtained from a corresponding classical model. For comparison the surface energies of several other alkali halides have been computed.
THE NUMBER DENSITY OF METEOR TRAILS OBSERVABLE BY THE FORWARD-SCATTERING OF RADIO WAVES
Authors: Pugh Robert E.
Published: April 2011

The number of meteor trails which can be detected by the forward-scattering of radio waves varies with the region of the sky under observation. The number density is determined theoretically, as a function of position relative to the transmitter and receiver.
AN EMISSION SPECTRUM OF THE DIACETYLENE ION: A STUDY OF SCHÜLER'S "T" SPECTRUM UNDER HIGH RESOLUTION
Authors: Callomon J. H.
Published: April 2011

Schüler and Reinebeck have described a new spectrum which was observed in a discharge through a mixture of an inert gas and the vapor of any of a number of organic compounds. This spectrum was labelled "T". Further experiments by the authors provided evidence that the carrier of the "T" spectrum was the diacetylene molecule. The "T" spectrum has now been reinvestigated using both normal and fully deuterated diacetylenes in a helium discharge and photographed on grating instruments with very high resolving powers. Previous vibrational assignments were extended, and the rotational structure was completely analyzed in four bands. The results, together with other evidence, show that the carrier of the "T" spectrum is the diacetylene ion, C4H2+. The vibrational and rotational constants differ but little from those of the diacetylene ground state. The spectrum involves a transition between the first excited state A2Πu(i) and the ground state X2Πg(i) of the ion and is analogous in detail to the well-known Fox, Duffendack, and Barker system of CO2+.
A CONSIDERATION OF RADIO STAR SCINTILLATIONS AS CAUSED BY INTERSTELLAR PARTICLES ENTERING THE IONOSPHERE: PART III. THE KIND, NUMBER, AND APPARENT RADIANT OF THE INCOMING PARTICLES
Authors: Harrower G. A.
Published: April 2011

In Parts I and II, as the result of an analysis of measurements of the scintillations of the radio source in Cassiopeia, it was suggested that interstellar particles, captured by the gravitational field of the Sun, contributed to the observed features. Arguments presented here lead to the conclusion that such particles must be hydrogen atoms. The number of hydrogen atoms reaching the Earth is estimated to be 6 × 1016/m.2/sec. Their energy averages 9 or 22 electron volts, depending on whether or not they are ionized. It is concluded that the effect of this infall on the Earth's ionosphere would be more than adequate to produce scintillations. The location of the radiant, subject to the possibility of some considerable error, is judged to be right ascension 17 hours, declination −30°. Based on this position of the radiant, the velocity of the interstellar hydrogen atoms in the vicinity of the Sun is found to have the components: tangential 28 × 104 m./sec., radial 2 × 104 m./sec., and transverse 0.2 × 104 m./sec, with respect to the plane of our galax
DIFFRACTION OF 3.2 CM. ELECTROMAGNETIC WAVES BY DIELECTRIC RODS: III. LUCITE IN. DIAMETER SEMICYLINDER, FIELDS VERY CLOSE TO SURFACE
Authors: McLay A. B. , Jordan C. E.
Published: April 2011

The diffraction fields near a long, semicylindrical, [Formula: see text] in. diameter rod of lucite, oriented in a nearly plane incident field of 3.2 cm. waves with plane surface towards or away from the source, have been reinvestigated in the region very close to the rod more thoroughly than previously (McLay and Subbarao 1956). The incident field was polarized parallel to the long axis of the semicylinder. In addition, the field near the rod when it was oriented with plane surface aligned with the axis of propagation and the field when the same rod was coated with thin aluminum foil and placed in turn in each of the three above-mentioned orientations have now been observed.A number of features in the diffraction patterns of the uncoated lucite rod have been qualitatively accounted for as resulting from effects of weak radiation after one or more internal reflections, or from evanescent waves close to a part of the surface where internal incidence is at angles greater than critical, superposed on one or more of the incident, directly transmitted and externally reflected radiations. The patterns a little away from the surface of the uncoated rod and the whole patterns of the aluminum-coated one are quite simple relatively and provide evidence of marked near-field diffraction.
CONSERVATION OF PARITY IN STRONG INTERACTIONS
Authors: Gupta Suraj N.
Published: April 2011

The conservation of parity in electromagnetic and mesonic interactions and the non-conservation of parity in the neutrino interactions are discussed on the basis of the principle of invariance under combined space inversion and charge conjugation.
AN ABSOLUTE DETERMINATION OF RESISTANCE
Authors: Romanowski M. , Olson N.
Published: April 2011

An absolute determination of resistance has been completed in the laboratories of the National Research Council, using a bridge which was originally derived as a modification of Campbell's network. It can be shown that this network can also be treated as a special case of the bridge used by Hartshorn for the comparison of equal mutual inductors. This latter aspect is a very valuable feature, for it means that the same basic network can be used for nearly all the a-c. operations, i.e. calibration of inductors in terms of the computed standard, measurement of self-capacitances and intercapacitances, and the inductance bridge. The change from the comparison bridge to inductance bridge is accomplished simply by replacing one of the inductors by one having twice its value and by shunting its primary by an appropriate resistor. By doing so, the very low value of the "potentiometer" in the comparison bridge increases so as to be equal to R1 = 1 Ω, the latter becoming the resistor whose value is to be determined in terms of inductance (length) and frequency (time). The computed value of the standard inductor being equal to 10 mh. nominal, the value 20 mh. is obtained by the addition method on a specially designed inductor.A complete analysis of the circuit, including all small terms (self-capacitances, intercapacitances, residual inductances), is made for all operations: comparisons of inductors, addition of inductances, and finally the main bridge. The methods for the evaluation of these small terms are the most important and are therefore given with some detail. This includes also the evaluation of a ratio of resistances that figures in the equation for R1. This is made by means of a resistance comparator and its auxiliary equipment. A complete measurement is quoted from our laboratory book.A total of over 100 such measurements of R1 in absolute units were made. Their average shows that the unit presently used in the N.R.C. laboratory (deduced from calibrations made on N.R.C. standards by other national laboratories) is about 8 parts in a million smaller than the unit given by our method. This absolute unit agrees very closely with units resulting from similar work done in various other national laboratories.
NOTE ON THE MOTION OF ELECTRONS AND HOLES IN PERTURBED LATTICES
Authors: Haering R. R.
Published: April 2011

A new set of orthogonal, localized functions is discussed. The functions bear the same relation to the functions of Luttinger and Kohn as the Wannier functions bear to the Bloch functions. The new functions are used to give an alternative derivation of the effective mass equation.
MEASUREMENTS WITH A WHOLE BODY COUNTER
Authors: McNeill K. G. , Green R. M.
Published: April 2011

An account is given of work on the measurement of the gamma radioactivity of humans. A steel room has been constructed, in which this gamma activity may be measured to a statistical accuracy of a few per cent in 30 minutes using a 5-in. NaI crystal as detector. The average potassium content of thirty 19-year-old males living in Ontario has been found to be 0.212% of body weight, and the average Cs/K ratio 51 μμc/g K.
POLARIZATION OF RADAR ECHOES FROM AURORA
Authors: Kavadas A. , Glass D. G.
Published: April 2011

Auroral radar echoes at very high frequency received at antennas sensitive to linearly polarized components in directions symmetrical to the plane of polarization of the vertically polarized transmitted wave and the ground plane indicate that the received wave, in addition to an unpolarized component, contains a linear component of polarization tilted in the general direction of the earth's magnetic field lines.
CRYSTAL GROWTH AND THE THERMODYNAMICS OF IRREVERSIBLE PROCESSES
Authors: Kirkaldy J. S.
Published: April 2011

The principle of minimum rate of entropy production is applied to steady-state transport processes in the neighborhood of an alloy crystal face growing into its melt. The procedure gives a satisfactory rationale of observed interface morphology. It is noted that segregation, which occurs in cellular or dendritic growth of alloys, is a direct manifestation of the system's attempt to minimize entropy production by conserving free energy. The general problems of growth of pure and impure single crystals from the melt and vapor are discussed.
SPINS OF EXCITED STATES OF Os188
Authors: King W. J. , Johns M. W.
Published: April 2011

Seven excited states of Os188 populated through the beta decay of Re188 have been studied by gamma–gamma angular correlation experiments. The data for the various cascades fit the following theoretical functions: (all gamma-ray energies are in kev and the description following each cascade refers to the first transition) 478–155 (2–2–0, 99.7% E2, δ +ve), 931–155 (0–2–0), 672–633 (2–2–0), 97% M1, δ −ve or 3–2–0, 94% M1, δ −ve or conceivably 4–2–0), 828–633 (2–2–0, 98% M1, δ −ve or conceivably 3–2–0, 80% M1, δ −ve), 1132–633 (0–2–0), and 1308–633 (2–2–0, 98% M1, δ −ve). Some attenuation occurred in the correlations involving the 155-kev gamma ray. The K-conversion coefficients for the 478- and 633-kev transitions have been measured as 0.023 ± 0.003 and 0.010 ± 0.002 respectively, confirming the E2 character for these transitions obtained by angular correlation. These results, coupled with data concerning log ft values and gamma-ray intensities, lead to the following spin and parity assignments for levels in Os188: 155 (2+), 633 (2+), 1086 (0+), 1306 (2+ or 3+), 1461 (2+), 1765 (0+), 1941 (2+), and 1958 (1+ or 2+).The 631–137 correlation data in Os186 was found to fit an attenuated 2–2–0 function with the first transition 99% E2 and δ −ve. This result supports the established decay scheme for this nucleus.
EFFECTIVE AND THERMAL NEUTRON CAPTURE CROSS SECTION AND RESONANCE CAPTURE INTEGRAL OF Pr-143
Authors: Roy J. C. , Roy L. P.
Published: April 2011

The effective neutron capture cross section,[Formula: see text]; the 2200 meters/sec neutron capture cross section, σ0, and the resonance capture integral, RI, of Pr-143 have been measured by an activation method. The values are: [Formula: see text], σ0 = 89 ± 10, and RI = 190 ± 25 barns respectively. The neutron fluxes have been measured with cobalt monitors. All these values have been calculated according to the Westcott convention, which has been outlined insofar as it can be applied to activation work.
THE CUMULATIVE FISSION YIELDS OF LIGHT MASS FRAGMENTS IN THE THERMAL NEUTRON FISSION OF Pu239
Authors: Fickel H. R. , Tomlinson R. H.
Published: April 2011

The relative cumulative yields of 19 light mass fragments of rubidium, strontium, yttrium, zirconium, molybdenum, and ruthenium formed in the thermal neutron fission of Pu239 have been determined with a mass spectrometer using the isotope dilution technique.The yields of the fission product isotopes of these elements, together with the previously published relative yields of three krypton isotopes, have made possible the determination of the absolute yields of 22 light fragment mass chains.
ON THE SPHERICAL OSCILLATOR NUCLEUS
Authors: Newton T. D.
Published: April 2011

The degree of consistency of an oscillator model of a nucleus is examined by means of a type of Hartree–Fock calculation based on a simple form of internucleon potential valid at low energies. An effective mass equal to 0.757 times the mass of a free nucléon is used. The oscillator wave functions are found to be not far from self-consistent and the oscillator frequency derived is physically reasonable, but the bound on the binding energy is not good. It is also shown that the oscillator wave functions are a good approximation for the state functions of particles bound in a finite potential well having the shape of a cutoff oscillator so that the Hartree–Fock calculation can be used to prescribe a shell model potential.
NEUTRON SOURCES FROM THE BERYLLIUM REDUCTION OF PLUTONIUM DIOXIDE
Authors: Michaud G. G. , Boucher R. R.
Published: April 2011

Sintered neutron sources have been prepared by reacting plutonium dioxide with beryllium metal powder. The reaction, forming a plutonium–beryllium alloy, proceeded very slowly at 750 °C but was nearly complete at 850 °C. Sintered, non-friable agglomerates were obtained by heating the reacted mixtures at 1250 or 1450 °C depending on the beryllium concentration. In the composition range of particular interest, i.e. Be/Pu atom ratios of 13:1 and above, the neutron output from the sintered products were from 93 to 98% of the theoretical neutron yield. The presence of BeO in the sinters was found to have negligible effect on the neutron output of the alloy. Studies of some factors affecting neutron output or sinter quality are also reported.
TABLES OF ROTATIONAL ENERGY LEVELS OF DEFORMED EVEN–EVEN NUCLEI
Authors: Moore R. B. , White W.
Published: April 2011

A digital computer has been used to extend calculations of rotational energy levels of deformed even–even nuclei treated in the manner of Davydov and Filippov. Tables are presented which may be useful for comparison with experimental energy levels of high spin such as are realized in Coulomb excitations by heavy ions.
THE FRICTION OF HEATED BISMUTH
Authors: Niven C. D.
Published: April 2011

An apparatus is described to measure the friction of heated bismuth at loadings up to 640 p.s.i. A coefficient for pyrex glass on bismuth near its melting point of 0.13 was indicated as a fair average value although figures down to 0.1 were also obtained. On surfaces where the metal was molten a value of 0.06 was measured. While bismuth has ice-like friction qualities up to a point, the author failed to prove that bismuth disobeys Amontons' law at high loading in the manner that ice does. To account for this, the crystal structures of bismuth and of ice are compared.
UNE ÉTUDE DU PHOSPHORE ROUGE PAR SPECTROMÉTRIE DE MASSE
Authors: Carette Jean-Denis , Kerwin Larkin
Published: April 2011

not available
APPLICATION OF FOURIER TRANSFORMS TO ANTENNA PATTERN SYNTHESIS
Authors: Villeneuve Alfred T.
Published: April 2011

The two-dimensional Fourier transform of the field quantities is employed to synthesize source distributions over plane rectangular apertures when a field distribution is prescribed at an arbitrary distance from the source. Several examples of application of the technique are included. The approximations involved are discussed.
DETERMINATION OF A PRESSURE COEFFICIENT FOR THE PHOTON COMPONENT OF COSMIC RADIATION
Authors: Bukata R. P. , Chin F. K. , Standil S.
Published: April 2011

A large crystal total absorption spectrometer has been used to obtain a value of (−.62 ±.05)% per nib for photons above 7 Mev and (−.86 ±.20)% per nib for photons above 35 Mev. The mathematical method used is described and a simple absorption model of the atmosphere is presented.
THE THEORY OF LONGITUDINAL PLASMA OSCILLATIONS IN THE FORMATION OF A RUNAWAY ELECTRON STREAM
Authors: Skarsgard H. M.
Published: April 2011

The theory of longitudinal oscillations accompanying the acceleration of electrons in a neutral plasma is investigated. Particular reference is made to an experiment with a plasma betatron supplemented by a strong longitudinal magnetic field. Various stability criteria are derived which show that for runaway electron streams of interestingly large intensity an interval of instability is always encountered during the initial acceleration. Calculations of the fluctuation energy built up during this interval have been made in order to determine the conditions for which the fluctuation energy is not expected to overtake the drift energy. For a two-stream plasma consisting of the runaway electron stream and a slow ion stream, it is found that even for relatively small accelerating electric fields rather intense runaway streams can escape disruption due to the instability (e.g. for E = 2000 volt m−1 runaway beam densities corresponding to currents of about 4000 amp, at relativistic energies, may be expected to escape disruption). However, if relatively few slow electrons are present in the beam the critical runaway beam density is drastically reduced. The effect of finite rise-time for the accelerating electric field is considered.
Excitation of oscillations by an electron current in a weakly ionized plasma
Authors: Pocobelli Gustavo
Published: April 2011

We investigate in the framework of linear kinetic theory the effect of neutrals on plasma oscillations generated by drift of the electrons in a boundless, stationary, homogeneous, Maxwellian plasma. It is assumed that collisions between charged particles and neutrals are dominant with respect to collisions between charged particles. The expected stabilizing effect of these collisions on the critical velocity and growth rate is confirmed and evaluated. Our results reduce to those of Klevans and Primack—the most accurate results to date for ion and electron plasma waves—in the collisionless, driftless case; to those of Bernstein and Kulsrud (with somewhat improved accuracy) in the collisionless case; and to those of Kadomtsev in the case of very high electron–ion temperature ratios and [Formula: see text], the wave number corresponding to the electron Debye length.
The nuclear spin of samarium-155
Authors: Eastwood H. K. , Summers-Gill R. G.
Published: April 2011

Atomic-beam experiments confirm that I = 3/2 for 155Sm.
The freezing points of high-purity metals as precision temperature standards. VIIIa. Sb: Apparatus, freezing techniques, and ingot morphology
Authors: McLaren E. H. , Murdock E. G.
Published: April 2011

This paper describes the apparatus and the freezing techniques that have been developed to determine the liquidus points (630.55 °C) of samples of high-purity antimony to a reproducible precision of ± < 0.0005 °C. Freezing plateaux steady to ± 0.0001 °C for long (hours) durations are readily obtained on freezing curves of high-purity antimony using an outside-nucleated slow induced freezing (ONSIF) technique in a balanced three-winding inconel block furnace. The pressure effect on the freezing temperature of antimony was determined as + 0.000 85 °C for 1 atm, which corresponds to a contraction on Sb solidification of 0.98%; a contraction on freezing is supported by volumetric measurements on the shrinkage pipes in Sb ingots and by observations on decanted and quenched (during freezing) ingots that Sb dendritic solid is more dense than Sb liquid.Metallurgical studies using decanting, quenching, and tracer techniques determined the ingot morphology during freezing and melting to verify that a satisfactory control of the transforming ingot had been attained for liquidus point realizations and to provide auxiliary information on the nature of solute segregation and segregate remelting for the interpretation of alloy melting-range comparisons on several samples of high-purity antimony described in Part VIIIb of this series of papers. Abundant evidence of the fragmentation of masses of large rod dendrites and the surface recontouring of dendrite spines by recalescent remelting was found in both decanted and quenched Sb ingots: the pileup of dendritic solid in the bottom of the crucible does not preclude precise temperature determinations on ONSIF freezes.
Density measurements of compressed solid and liquid argon
Authors: Witzenburg W. van , Stryland J. C.
Published: April 2011

A method is described by which the equation of state of liquids and reasonably soft solids can be determined experimentally. A unique feature of the apparatus is that while the quantity of material occupying a known volume is weighed, pressure and temperature are measured concurrently. First results are reported for solid and liquid argon in the temperature range from 96 to 154 °K and at pressures from about 100 to 2000 kg/cm2. The liquid data determine the PVT surface to within 0.1% for each of the variables. Data for solid argon have so far been limited to a zone of 20-degree width along the melting line. Thermal expansion and compressibility of the liquid are computed. From the volume change on melting it is concluded that the latent heat increases linearly over the full pressure range.
Nonexistence of excitonic insulators in one and two dimensions
Authors: Walker M. B.
Published: April 2011

The Bogoliubov inequality is used to prove the nonexistence of the excitonic insulating phase in one and two dimensions for systems of electrons described by three different many-band models with interactions. The proof is carried through (1) for arbitrary two-particle interactions with an interaction potential which goes to zero faster than [Formula: see text] (n being the number of dimensions) at large [Formula: see text], (2) for two-particle interactions of arbitrary range, provided only the so-called Coulomb and exchange parts of the interaction are retained and the remainder is neglected, and (3) for the simplified isotropic two-band model suggested for the excitonic insulator by Des Cloizeaux.
Electron-density profiles from laser scattering
Authors: Nodwell R. A. , Kamp G. S. J. P. van der
Published: April 2011

The electron density as a function of position within a plasma jet has been determined by measurements of the coherent scattering of laser light. The electron-density profiles thus obtained are compared with those obtained from spectroscopic measurements. It is shown that the width of the satellites observed in earlier work may be accounted for by the electron-density gradients.
Search for low-altitude acceleration mechanisms during an auroral substorm
Authors: McDiarmid I. B. , Budzinski E. E.
Published: April 2011

Two Black Brant rockets were fired simultaneously from Fort Churchill during an auroral substorm. Electron spectra and angular distributions were examined at altitudes up to 800 km in an attempt to observe the effects of acceleration or loss mechanisms acting on the particles at low altitudes. In particular, the variation of the pitch-angle distribution in the loss cone for electrons with energies greater than 40 keV and near 10 keV was examined as a function of altitude. It was found that the distributions within the loss cone at higher altitudes decreased more slowly with pitch angle than expected on the basis of the observed distributions at low altitudes if no forces other than the earth's magnetic field act on the particles. The discrepancy was larger for 10-keV electrons than for 40-keV electrons. It is concluded that mechanisms exist at altitudes below 800 km which can alter the magnetic moments and/or the energies of the particles. No satisfactory explanation of the observed discrepancy has been found. An attempt was made to interpret the results in terms of wave-particle interactions which could give rise to pitch-angle diffusion, but the magnetic-wave amplitude required is at least two orders of magnitude larger than observed values.
Absorption spectrum of the NO molecule. VIII. The heterogeneous (2Σ–2Π) interactions between excited states
Authors: Jungen Ch. , Miescher E.
Published: April 2011

Heterogeneous perturbations 2E+ ~ 2Π of largely different magnitudes are observed with high resolution in the vacuum-ultraviolet absorption and in the infrared emission spectrum of the NO molecule. The rotational interactions between 2Σ+ Rydberg states and levels of the B2Π non-Rydberg state are shown to be "configurationally forbidden", but produced by the configuration interaction between the non-Rydberg levels and 2Π Rydberg states. The latter together with the 2Σ+ Rydberg states form p complexes. In this way the interactions display the l uncoupling in the complexes; they can be evaluated theoretically and can be analyzed fully. The cases of the strong interactions D2Σ+(v = 3) ~ B2Π(v = 16)and D2Σ+(v = 5) ~ B2Π(v = 21) and of the weaker D2Σ+(v = 1) ~ B2Π(v = 11), all three observed as perturbations in ε bands crossing 3 bands, are discussed in detail. It is further shown that perturbations between γ bands and β bands as well as perturbations between analogous bands of higher principal quantum number are absent, and thus the assignment of the A2Σ+ and E2Σ+ states to the s Rydberg series is confirmed.
The mass distributions of meteoroids and asteroids
Authors: Jones J.
Published: April 2011

A theory of the mass distribution of interplanetary particles has been developed and it has been shown that, provided the solid debris resulting from the erosion due to mutual collisions is not important, then the asymptotic mass distribution is a power law. The predictions of this theory are compared with observations, and very good agreement is found in the case of meteor streams and asteroids > 2km in diameter. For sporadic meteoroids it was found that a second process was needed to explain the observed mass distribution, and the condensation of some components of the interplanetary gas is shown to be consistent with observation.
Experimental studies of the magnetic and phonon excitations in cobalt fluoride
Authors: Martel P. , Cowley R. A. , Stevenson R. W. H.
Published: April 2011

The excitations of cobalt fluoride have been studied with the technique of slow-neutron inelastic scattering. A triple-axis crystal spectrometer was used throughout in its constant Q mode of operation. Several of the branches of the phonon spectra were measured and are in reasonable agreement with calculations based on a very simple rigid ion model. The magnetic excitations are of interest because the Co2+ ion has unpaired orbital angular momentum which gives rise to several low-lying energy levels. Excitations have been observed from the ground state to the next three excited states in the antiferromagnetic phase and their dispersion and temperature dependence obtained below, near, and above the Néel temperature. The temperature dependences of the excitations to the different excited states are not the same. The measurements on the magnetic excitation branch of lowest frequency show that, contrary to current theories of magnetism, fairly well-defined magnetic excitations occur to at least 1.5TN Another excitation, which gave a weak scattering intensity, was also observed and it is suggested that this may be associated with a distortion of the crystal structure.
Electromagnetic scattering from cylindrically and spherically stratified bodies
Authors: Latham R. W.
Published: April 2011

A method is developed for calculating the electromagnetic field scattered by certain types of bodies. The bodies consist of inhomogeneous media whose constitutive parameters vary only with the distance from some axis or point of symmetry. The method consists of an extension of the invariant embedding method for treating wave-scattering problems. This method, familiar in the case of plane stratified media, is extended to handle cylindrically and spherically stratified media.
Electromagnetic fields in a spherical cavity with a concentric anisotropic shell system
Authors: Wait James R. , Large David B.
Published: April 2011

The boundary-value problem consisting of a double-sheathed slotted sphere is solved. The inner sphere or core is perfectly conducting except for an infinitesimally thin annular ring which is excited by a voltage V0. Two thin plasma shells are located concentrically about the core. The inner one is effectively isotropic, whereas the outer one is anisotropic by virtue of a d-c. magnetic field whose radial component is assumed constant for present purposes. It is indicated that the cavity resonances of the system are significantly damped by the presence of the inner shell.
Electromagnetic transition strengths in 14C and 14N
Authors: Allen K. W. , Alexander T. K. , Healey D. C.
Published: April 2011

The lifetimes of the 5.10-MeV and 5.83-MeV levels in 14N and the 6.72-MeV level in 14C have been measured using a recoil distance method and the T(12C, nγ)14N and T(12C, pγ)14C reactions respectively. The lifetimes are 12.4 ± 1.4 and 18 ± 2 ps for the 5.10-MeV and 5.83-MeV levels in 14N respectively and 97 ± 15 ps for the 6.72-MeV level in 14C. These measurements are combined with previous determinations of gamma-ray branching and multipole mixing ratios to obtain the strengths of the transitions involved. Comparison of the strengths with recent calculations shows agreement in general. The ground-state E3 transitions from the 5.10-MeV level in 14N and the 6.72-MeV level in 14C are enhanced by 2.2 ± 0.7 and 3.3 ± 0.8 Weisskopf units respectively. The isotopic spin selection rule for E1 and M2 transitions in the self-conjugate nucleus 14N is observed and discussed for some transitions. For example, the allowed M2 transition from the 5.10-MeV to the 2.31-MeV level has [Formula: see text] whereas the isotopic spin forbidden M2 part of the 5.10-MeV to ground-state transition has [Formula: see text]
Densities of interstellar hydrogen clouds
Authors: Ahlborn B.
Published: April 2011

With simple gas dynamical theory one can calculate three properties of plane and steady supersonic discontinuity fronts: the compression ratio ρ2/ρ1, the density of the undisturbed medium ahead, and the power input W per unit area of front. These calculations do not require knowledge of the absorption mechanism or the spectral distribution of the absorbed (or emitted) radiation, but are based on measurements of particle velocity, density, and temperature behind the front. The calculations were applied to radio observations of galactic H II regions by Mezger and Henderson (1967) and Mezger and Höglund (1967). The derived average density for 11 hydrogen clouds surrounding the observed H II regions corresponds to n(H I) = 50 cm−3, assuming complete dissociation. The objects Orion A and IC 434 stand out with n(H I) = 450 and 405 cm−3, respectively (see Table I). The average power input is W = 5 × 10−3 erg/cm2 s.
Many-quantum transitions in conduction electron spin resonance
Authors: Koss T. A. , Alexander S. , Schwerdtfeger C. F.
Published: April 2011

Resonance absorption spectra have been observed which may be interpreted as many-quantum transitions where the quantization is along the effective field in the rotating frame. The spin system used was that of the conduction electrons in Li metal in a crystal of neutron irradiated LiF. An analysis of the experimental results using a modified Bloch equation under the assumptions that [Formula: see text] and that the spin system relaxes towards the instantaneous field is presented. The agreement between theory and experiment is excellent.
Thermoelectric powers of primary solid solutions of Au, Cd, Zn, In, Ge, Tl, and Sb in silver
Authors: Wright L. S.
Published: April 2011

The thermoelectric powers and resistivities of primary solid solutions of Au, Cd, Zn, In, Ge, Tl, and Sb in silver were measured over the temperature range 90–240 °K. The characteristic thermoelectric powers of the impurities have been determined in the diffusion region by the Nordheim–Gorter relation. Furthermore, the straight line (diffusion thermoelectric power versus temperature) arising at high temperatures has been extrapolated into the phonon-drag region and Nordheim–Gorter plots have been made using points from this extrapolation.
Theory of inductive shielding
Authors: Latham R. W. , Lee K. S. H.
Published: April 2011

A mathematical theory of low-frequency electromagnetic shielding is constructed on the basis that an appropriate set of boundary conditions can be derived to duplicate the effect of the shield's wall on the fields within the shield. Shields with electrically thin shells are considered in detail; mathematical methods that are best suited for computational purposes are presented for calculating the shielding effectiveness of such a shield of arbitrary shape. Shells with arbitrary electrical thickness are also treated, but in less detail, since the shielding problem involving this kind of shell is shown to be different from but no more general than the shielding problem involving electrically thin shells. Explicit results are given for shields of particular shape.
Magneto-optical properties of an optically pumped medium
Authors: Verschueren M.
Published: April 2011

The magneto-optical properties of a system subject to an optical and a radio-frequency radiation are calculated. The frequency of both radiations is close to the resonance frequencies of the system and as such they have a strong effect on its properties. The frequency shifts induced by optical radiation are obtained. Relations between the complex index of refraction and the frequency shifts are discussed.
The nature of the photolysis of silver at an oxide semiconductor surface
Authors: Clark W. C. , Vondjidis A. G.
Published: April 2011

The photolytic reduction of silver ions adsorbed from solution on solid oxide surfaces is described. Studies of silver on titanium dioxide exposed to ultraviolet-light irradiation show a photochemical change that is very dependent on the state of hydration of the surface. The diffuse reflectance of the material in the form of compacted powders decreases with exposure. For dry samples it can be shown that the kinetics of the process follows an exponential rate law. The visible and infrared spectral characteristics are investigated and interpreted in terms of a model postulating electronic trapping centers localized at the surface of the oxide. Evidence is presented showing that groups of silver atoms are able to dissociate and rearrange on the solid surface. The nature and mechanism of the interaction with the semiconductor oxide surface is discussed.
Vertically propagating waves in an atmosphere with Newtonian cooling inversely proportional to density
Authors: Lindzen Richard S.
Published: April 2011

The behavior of vertically propagating waves is investigated for an atmosphere with Newtonian cooling, where the cooling rate coefficient is very small near the ground and increases inversely with the atmosphere's density away from the ground. This model for dissipation is unrealistic. However, the results obtained are very similar to those obtained by Yanowitch (1967a, b), who investigated the behavior of waves in a viscous atmosphere where the kinematic viscosity is inversely proportional to atmospheric density. The present calculations are, in general, far simpler than those of Yanowitch, and suggest that many of his results follow from the variation of dissipation with height and not from specific details of the physics. It is suggested that the present calculations may provide convenient estimates of the effects of dissipation in more realistic situations.
Seeming time-reversal violation in higher-order weak interactions
Authors: Leibbrandt G.
Published: April 2011

It is demonstrated within the framework of the intermediate vector boson theory that the interference between purely weak interaction graphs of different orders in g can lead to a seeming violation of time reversal T. This seeming violation is implied by the presence of triple scalar products in experimental cross sections, [Formula: see text], and may occur even if the primary weak interaction Hamiltonian is T invariant. The total scattering amplitude for a set of Feynman graphs is characterized by coefficients Gi. A necessary condition for the appearance of time-odd correlations is that the ratio Gi/Gj be complex.The theory is applied to the scattering of a neutron by an incident high-energy neutrino: νc + n → p + e−. Triple scalar products are shown to arise specifically from the interference between real and imaginary components of the total amplitude, constructed here from second- and sixth-order uncrossed ladder graphs. The essential imaginary components are divergence-free and emerge from poles in the integrand of the eightfold integral (sixth-order graph).Triple scalar products in dσ are proportional to m−6g8 (ln s)/s; there is no cancellation from crossed graphs of order six. Ladder graphs treated on an individual basis do not give rise to J ∙ p1 × p2 terms.
Theoretical prediction of the singlet-triplet intercombination separations for NH, OH+, PH, and SH+
Authors: Cade Paul E.
Published: April 2011

The singlet–triplet (a1Δ–X3Σ−) intercombination separations for NH, OH +, PH, and SH + are predicted to be 1.63, 2.19, 0.95, and 1.16 eV, respectively. These predictions are expected to be good to ~0.1 eV and are based on a quantitative model of the relationship of the united atom and the diatomic hydride, AH. The intercombination separations as calculated via Hartree–Fock energies are corrected for the "change in correlation energy" involved in the transition making use of united-atom changes in the correlation energy.
Hall studies on encapsulated CdSe films
Authors: Brodie D. E. , Yeh G.
Published: April 2011

A technique for encapsulating CdSe films to obtain the flat band condition at the semiconductor surface is discussed and the results of Hall studies on suitably encapsulated films are presented. Results obtained with these films are consistent with a crystallite–grain-boundary model, where the mobility is limited by intercrystalline barriers, when the carrier concentration is not too large.
Electrical resistivity measurements in palladium–hydrogen alloys
Authors: Haywood C. T. , Verdini L.
Published: April 2011

The resistivity of palladium and palladium–hydrogen alloys has been studied in the temperature range 2–300 °K. At low temperatures (10 °K < T < 60 °K), it is found that ρ1 is proportional to Tn with n = 3.1 for pure palladium; but n decreases to 2.3 for an alloy with H/Pd = 0.25. For high concentrations and at low temperatures, the resistivity is found to be dependent upon the time and rate of cooling through the [Formula: see text] transformation. The residual resistivity is lower for faster cooling rates.The increase in resistivity due to 1 at. % hydrogen in palladium is calculated and found to be of the same order of magnitude as that for interstitials in other f.c.c. metals, but less then that found for hydrogen in the b.c.c. transition metals tantalum and niobium at room temperature.
Single electron capture cross sections of the 2P3/2 and 2P1/2 state argon and krypton ions
Authors: Williams J. F.
Published: April 2011

The ionization probability curves of argon and krypton atoms within 1 eV of threshold have been studied for electron impact with an average electron energy distribution of 0.035 eV (FWHM). In krypton, changes in the slope of the ionization probability curves occur at electron energies close to the spectroscopically observed autoionization levels between the 2P3/2 and 2P1/2 levels. Ions which have been formed in such a manner are then used as primary ions in charge-transfer reactions. Total single electron capture cross sections have been measured for 2P3/2 and 2P1/2 state argon and krypton ions incident upon argon and krypton atoms, respectively. Upon the presumption of the applicability of the adiabatic hypothesis, it appears, for single electron capture reactions of krypton ions upon krypton atoms over the relative energy range 500–1500 eV, that (a) the reaction 2P3/2 → 2P3/2 is dominant over the reaction 2P3/2 → 2P1/2, (b) the cross section for the 2P3/2 → 2P3/2 reaction is greater than the 2P1/2 → 2P1/2 reaction cross section, and (c) little information can be deduced for the relative values of the forward and reverse [Formula: see text] reaction cross sections.
A Gödel-type solution of the Einstein–Maxwell equation
Authors: Wilson S. J.
Published: April 2011

A Gödel-type solution of the Einstein–Maxwell equation is presented, using the equivalent Rainich equations.
Three-site correlation functions of the two-dimensional Ising model
Authors: Pink D. A.
Published: April 2011

Three-site correlation functions of a square lattice of the form [Formula: see text] have been analytically calculated for all temperatures. It has been found necessary to evaluate the inverse of t × t Toeplitz matrix as t → ∞, which has been done by using the Wiener–Hopf technique. The results are used to give an expression for the magnetization at any site in a row when one of the bonds in that row is a defect bond, and comments are made upon applications to decorated lattices.
The orthogonality assumption in the Hartree–Fock approximation for 2pn3p configurations
Authors: Fischer Charlotte Froese
Published: April 2011

Hartree–Fock (HF) results for Na+ 2p53p1S and Ne+ 1s2p53p2S are reported. In order for the SCF process to converge, additional orthogonality constraints to the corresponding 2p6 states had to be introduced. The resulting 2p functions were nodeless. Similar calculations were performed for O 2p33p2P and Ne+ 2p43p2P for which standard HF results were available. A comparison of the two methods indicates that, unlike the He 1s2s1S case, the additional orthogonality constraint did not improve the total energy although it removed the extra node from the 2p function.
The absorption spectrum of the free SiH2 radical
Authors: Dubois I.
Published: April 2011

The absorption spectrum of SiH2 in the visible region has been photographed at high dispersion and the rotational structure of three bands has been analyzed. In the lower electronic state 1A1 the HSiH angle is 92° 5′ and the Si–H distance 1.516 Å, while in the upper state these parameters are 123° and 1.487 Å, respectively. The observed bands correspond to excitation of the bending vibration [Formula: see text] in the upper state. In the lower state, only one excited vibrational level, 010, has been observed, yielding [Formula: see text].
Study of moving striations in plasmas. III. The fast type "r" and the determination of the ionization frequency dependence on the electron mean energy
Authors: Šícha Miloš , Drouet M. G.
Published: April 2011

For ionization waves of small amplitude, the linearized equations of conservation for the particles and for the electron energy are applicable. A detailed study of these linearized equations reveals that the value of the ratio De/μe of the diffusion coefficient to the mobility for electrons and the derivative of the ionization frequency with respect to the electron mean energy αi′ may be determined from measurements of the phase difference between the variations of the electron temperature and the electron density in fast moving striations of the type "r". Some measurements are also reported and some values for De/μe and αi′ obtained.
Hyperfine interactions in the J = 5 states of 147Sm and 149Sm
Authors: Robertson R. G. H. , Waddington J. C. , Summers-Gill R. G.
Published: April 2011

The hyperfine interaction constants Ak(5) have been measured in 147Sm and 149Sm. Consideration of the k = 2 results together with Woodgate's values of A2(J) for J = 1 to 4 shows that his nonrelativistic treatment of the electric quadrupole interaction in samarium is inadequate but that a relativistic one gives excellent agreement. The effect cannot be confused with a possible configuration interaction as it can in the case of the magnetic dipole interaction. Allowance for the effects of octupolelike second-order corrections and more precise computation of the dipole- and quadrupole-like corrections markedly affect the published results for the hyperfine constants in the lower J states, but the revision does not improve the agreement with the theoretical expressions. It would appear that Conway and Wybourne's analysis of the breakdown of L–S coupling in the nominally 7F ground term is not adequate, particularly for the computation of the coefficient of the sC2 term.
Self-diffusion in gold single crystals at low temperatures
Authors: Whitton J. L. , Kidson G. V.
Published: April 2011

Self-diffusion in gold single crystals has been studied at temperatures between 335 to 390 °C for times between 15 and 30 min. The concentration profiles, obtained by use of a sensitive sectioning technique, consist of a region that appears to be characteristic of bulk diffusion, followed by a deeply penetrating 'tail' that is structure sensitive. Diffusion coefficients extracted from the initial portion of the curves are somewhat larger than those predicted from an extrapolation of high temperature measurements. The results are interpreted in terms of a combination of normal lattice diffusion and fast diffusion along dislocations.
Electronic absorption spectrum of the NCS free radical
Authors: Dixon R. N. , Ramsay D. A.
Published: April 2011

Absorption bands of NCS between 3300 Å and 4000 Å have been assigned to two electronic band systems, A(2Πi) – X(2Πi) with its origin at 26 054 cm−1, and B(2Σ+) – X(2Πi) with its origin at 26 844 cm−1. Rotational analyses have been carried out for the stronger bands, yielding rotational constants B0 = 0.2036 cm−1 (A state), B0 = 0.1906 cm−1 (A state), and B0 = 0.1969 cm−1 (B state). In addition to vibronic interactions within the two 2Πi states (Renner effect) there is considerable evidence for vibronic interaction between the A(2Πi) and B(2Σ+) states.
Calculation of the transverse conductivity for electrons interacting with waves in strong electric fields
Authors: Spector Harold N.
Published: April 2011

We have obtained the transverse a.c. conductivity for electrons interacting with waves in the presence of strong d.c. electric fields. The presence of the d.c. electric field leads to the introduction of a drifted distribution function for the electrons and a complex, field-dependent temperature. The expression for the transverse a.c. conductivity can be used to find the effects of the electric field on the propagation and absorption of waves in solids which induce transverse electric fields. We have applied our results to the interaction of electrons with transverse optical lattice vibrations and find that for all values of ql, it is the drifted distribution function which leads to the amplification of the waves.
Frozen core approximation for atoms and atomic ions
Authors: McEachran R. P. , Tull C. E. , Cohen M.
Published: April 2011

Properties of the frozen core approximation for atomic systems containing one valence electron in addition to completely filled shells are derived. It is shown that, in addition to computational convenience, the procedure enjoys certain theoretical advantages over the standard Hartree–Fock approximation.