bluuebunny/crossref_metadata_2025 huggingface dataset:
THE THERMODYNAMICS OF DILUTE TERNARY AUSTENITE SOLUTIONS
Authors: Kirkaldy J. S. , Purdy G. R.
Published: April 2011

A model based on nearest-neighbor interactions and regular behavior is used to calculate the thermodynamic activity of dilute ternary solutions of austenite (face-centered cubic iron) containing an interstitial and a substitutional component. The results, based on a standard state at infinite dilution, are[Formula: see text]and[Formula: see text]where N1and N2 are the mole fractions of the interstitial and substitutional solutes, respectively, and the [Formula: see text]'s are pair interaction energies. The symmetry relation existing between the coefficients in the above draws attention to a symmetry relation existing for an arbitrary empirical expansion of the activities for dilute solutions. The two-parameter relation for a1 accurately represents the data for Fe–C–Mn, Fe–C–Si, and Fe–C–Ni in the dilute range.
DESIGN OF RADIO TELESCOPES FOR EXTRAGALACTIC SURVEYS
Authors: Harrower G. A.
Published: April 2011

In order to make best use of the economic resources available for the construction of a radio telescope, it is usually desirable to design the instrument so that the number of sources resolved, Nr, will equal the number of sources detected, Nd. This paper presents expressions for Nr as a function of antenna diameter D, and for Nd as a function of the receiver parameters and the antenna area A and gain G. The condition Nr = Nd leads to the required values of A/D2 as a function of both wavelength and beam angle. The choice of a long wavelength for extragalactic observations is shown to have several advantages, including large Nd and small A/D2 values.
A MULTIPLE-PROBE MICROWAVE SYSTEM FOR PLASMA STUDIES
Authors: Osborne F. J. Fitz
Published: April 2011

This paper describes a fast-acting microwave diagnostic system which was developed for use with non-repetitive plasmas, such as those in shock tubes and pulsed discharges, and which has proved useful in a wide variety of experimental configurations. The system may be used for either reflection or transmission measurements and gives a polar display of phase and amplitude in conjunction with timing marks. Some of the principal features are wide dynamic range, expansion of high attenuation regions of the display, and a presentation of data which is readily assessed visually. The system has been used at microwave frequencies of 9.2 kMc, 9.7 kMc, 23.5 kMc, and 34.5 kMc, with sampling periods from 0.1 msec to 0.1 μsec at 50% duty cycles.
RAPID MEASUREMENT OF N2+ ROTATIONAL TEMPERATURES IN AURORA
Authors: Hunten D. M. , Rawson E. G. , Walker J. K.
Published: April 2011

A description is given of a photoelectric "temperature photometer" which gives a temperature reading from aurora in about one second. It uses two narrowband interference filters to measure the intensity in two parts of the bright N2+ band at 3914 Å, and a third to allow a background measurement. The reading is presented on a meter and is independent of the auroral intensity over a wide range. Observations of aurora have permitted construction of a temperature profile for the atmosphere from 95 to 170 km, showing a gradient of 6.0° K/km. A lowest temperature of 140 ± 20° K was observed for a period of several minutes. Diffuse surfaces appear from their temperatures to occur anywhere from 100 to 160 km.
DIURNAL AND SEASONAL VARIATIONS IN D-REGION ELECTRON DENSITIES DERIVED FROM OBSERVATIONS OF CROSS MODULATION
Authors: Barrington R. E. , Thrane E. V. , Bjelland B.
Published: April 2011

Pulsed cross modulation, arising in the region from 60 to 80 km, has been observed during undisturbed days in the spring, summer, and fall of 1960. The manner in which these observations were obtained and the uncertainties associated with the electron-density profiles determined from them are discussed.Average electron-density profiles for each hour of quiet spring days have been deduced. These show that the most rapid changes in electron density occur within one hour of ground sunrise and sunset. Around sunrise a rather uniform layer of about 100 electrons/cc is created almost simultaneously throughout the entire region from 60 to 80 km. As the day progresses, the average electron density between 70 and 80 km changes by a factor of about 10, while the average density between 60 and 70 km changes by only a factor of 2.These features of the D region are discussed in the light of theoretical predictions which assume that cosmic rays and solar Lyman-alpha radiation account for the normal ionization in this region.
PROBE STUDIES OF HELIUM AFTERGLOWS DOMINATED BY COULOMB INTERACTIONS
Authors: Olson O. D. , Skarsgard H. M.
Published: April 2011

Probe measurements of electron energy and density decays have been carried out in low-pressure helium afterglows. The plasma was contained in a toroidal chamber. A weak, azimuthal magnetic confining field of 40 gauss was used. Strict criteria have been satisfied to ensure reliable operation of the double probe employed for the measurements. Pressures used were in the range from 18 to 61 microns. The decay of electron density was found to be controlled by a type of ambipolar diffusion dominated by electron–ion collisions. The decay of electron energy is predominantly an equipartitioning process between the energetic electrons and the less energetic helium ions and atoms; electron–ion interactions account for the greater part of the cooling. Within certain limits the results confirm the applicability of the statistical theory employed to describe electron–ion interactions. They also provide a test of the probe technique employed for the measurements.
A STUDY OF AURORAL ABSORPTION AT 30 MC/S
Authors: Hartz T. R. , Montbriand L. E. , Vogan E. L.
Published: April 2011

The occurrence of auroral absorption, as observed over a two-year period at six Canadian stations extending in a north–south line between Resolute Bay and Ottawa, is discussed. On the average, the zone of maximum occurrence of auroral absorption is located near 63° geomagnetic latitude but tends to shift several degrees farther south during periods of strong magnetic activity. The occurrence falls off rapidly to the north of the zone maximum and there is no indication of an inner zone of auroral absorption activity. Contour plots are used to illustrate occurrence as a function of geomagnetic latitude and mean geomagnetic time. The resulting pattern shows a principal maximum near 0800 hours and a secondary maximum an hour or two before geomagnetic midnight. The pattern appears to fit the theoretical model of high-latitude disturbances as developed by Axford and Hines, and the possibility is discussed that there are two distinct phases in this disturbance pattern that correspond to the two diurnal maxima in the auroral absorption data.
THE EFFECT OF ENERGY AND INTEGRATED FLUX ON THE RETENTION AND RANGE OF INERT GAS IONS INJECTED AT KEV ENERGIES IN METALS
Authors: Brown F. , Davies J. A.
Published: April 2011

Two experimental factors limiting the use of ion-bombardment techniques in atomic range studies have been investigated: namely, the fractional retention of the incident beam, and the target saturation phenomenon. The fractional retention, or sticking factor, has been measured for Xe133 in Be, Al, Ni, Zr, Ag, Ta, W, and Au, and for Ar41 and Kr85 in Al and W, as a function of bombardment energy from 1 to 150 kev. The results indicate that, below about 5 kev, range measurements are of doubtful significance; in some cases, this energy limit for a reliable range measurement is considerably higher than 5 kev. A qualitative interpretation of the observed sticking factors is given. The saturation phenomenon in aluminum has been studied by injecting radioactive Xe in trace amount, either before, after, or during a bombardment with one of the stable Xe isotopes, and measuring the final distribution of the embedded radiotracer. The results provide information on the mechanism of target saturation. Bombardment with 2–3 μg of xenon/cm2 is found to reduce markedly the observed penetration depth of a 30-kev beam, thereby indicating the necessity of trace bombardments for accurate range measurements in this energy region.
PHONON BROADENING OF IMPURITY SPECTRAL LINES: I. GENERAL THEORY
Authors: Nishikawa Kyoji , Barrie Robert
Published: April 2011

The theory of the phonon broadening of impurity spectral lines is discussed within the framework of a Kubo-type formulation of the adiabatic dielectric susceptibility and the subsequent calculation of this using double-time Green's functions. The interaction of the bound electron (or hole) with the lattice vibrations is assumed to be weak and is treated as a small perturbation of the independent systems of electron and vibrating lattice; the use of the adiabatic approximation is thereby avoided. The cases in which the bound carrier states are degenerate and nondegenerate are discussed separately. The results are compared with previous work in the field.
CALCULATION OF THE SURFACE ENERGY OF THE {110} FACE OF SOME CRYSTALS POSSESSING THE FLUORITE STRUCTURE
Authors: Benson G. C. , Claxton T. A.
Published: April 2011

A method of calculating the surface energy of an ionic crystal is outlined and illustrated by application to the {110} face of crystals having the fluorite structure. Numerical results are given for CaF2, SrF2, and BaF2, and are compared with values calculated previously for the {111} face of these crystals.
THE OCCURRENCE AND CHARACTERISTICS OF RADAR AURORAL ECHOES AT 488 AND 944 MC/S
Authors: Blevis B. C. , Day J. W. B. , Roscoe O. S.
Published: April 2011

Radar backscatter observations of auroral ionization have been made from Ottawa on two similar systems operating at 488 and 944 Mc/s. These systems, as nearly scaled as was practicable, were operated almost continuously during the period from May 1959 to April 1961, inclusive.Narrow-beam transmitting and receiving antennas were used. They were each fixed in position to intercept the ionosphere at auroral heights in the region where the orthogonality condition for specular reflection is most nearly satisfied. A magnetometer recorded the magnetic disturbance at ground level at a point under the echoing region. Measurements were made of the time, amplitude, range, and frequency spectrum of the auroral echoes on each of the two frequencies, at both the transmitted and orthogonal polarizations.The data obtained indicate a double-peaked night time maximum in the occurrence of auroral echoes. A slight but distinct minimum appears just before local midnight. Equinoctial maxima are observed in the seasonal variation. The probability of occurrence of echoes increases rapidly with increasing magnetic disturbance. The average Doppler frequency shift of the echoes exhibits a systematic diurnal variation. There is a reversal in the direction of apparent motions, coincident with a change in sign of the average magnetic disturbance, and occurring at about the same time as the night time minimum in occurrence. From the two frequency data, echo cross section is found to vary as about the seventh power of the wavelength. There is no distinct evidence of depolarization or rotation of the plane of polarization of the echoes.Observations of the Doppler frequency shifts are interpreted in terms of the motions of auroral ionization. The wavelength dependence of auroral echoes is used to infer certain properties of the scattering medium.
THE EFFECT OF THE ELECTRON CORRELATION ON THE ELECTRICAL RESISTIVITY OF LIQUID METALS
Authors: Endo Hirohisa , Suekane Shota
Published: April 2011

An elementary theory of the electrical resistivity of monovalent liquid metals is given. On using the theory of the plasma oscillations of conduction electrons, the electron–ion interactions are separated into two parts: one gives the effective electron–ion interactions which are screened as the result of the effects of the plasma oscillations of the conduction electrons and contributes directly to the electrical resistivity; the other describes the interactions between the ions and the plasma oscillations. The screened electron–ion interaction is defined as the pseudo-potential of the ion.The theory constructed on the basis of the free-electron model is applied in the first instance to estimate the electrical resistivity of liquid sodium near the melting point. Callaway's potential and the correlation function of ions determined from neutron diffraction experiments are used and the mean free path of a conduction electron is calculated numerically. Therefore, in our theory, the "plasma term" and the "structure term" of Ziman's theory are not treated separately.
NUCLEAR SPIN RELAXATION IN GASES AND LIQUIDS: II. MOLECULAR HYDROGEN
Authors: Bloom Myer , Oppenheim Irwin
Published: April 2011

T1 and T2 in H2 are expressed in terms of correlation functions of the intamolecular interactions in the Schwinger model. A relationship between these correlation functions and correlation functions of the intermolecular interactions is derived. An approximate theory of the influence of higher rotational states is given.
PLANE WAVE SPECTRA IN GRATING THEORY: I. SCATTERING BY A FINITE NUMBER OF BODIES
Authors: Millar R. F.
Published: April 2011

A scalar plane wave is incident on a grating of N cylinders. A solution of the scattering problem, useful when N is large, is the ultimate goal. It is suggested that this may be accomplished by solving first the problem for a semi-infinite grating; this may be solved in terms of the scattering properties of an infinite grating, which, in turn, depend on the properties of an isolated cylinder.In the present paper, attention is confined to certain aspects of scattering by a few (in particular, one or two) cylinders. The field scattered by the cylinders is expressed as a sum of continuous plane wave spectra with amplitudes unknown, the scattering amplitude functions being considered as given for each cylinder in isolation. The field is studied, both outside the grating and between the elements. The convergence of the integral representation for the scattered field is treated in detail. Consequences of analyticity in the spatial variables of the scattered field are discussed; it is shown that the integral representation provides the continuation of the solution into a scatterer up to the convex hull of singularities of the field scattered by an isolated cylinder. Integral equations relating the scattering functions for cylinders in the grating and in isolation are derived. The uniqueness of the solution of these equations under a variety of boundary conditions is discussed by an indirect method; the case of two cylinders is treated in detail. It is inferred that there is at most one solution whose growth in the complex plane of the angle of observation is appropriate to scattering by a physical body.
NEUTRON DIFFRACTION DETERMINATION OF THE HYDROGEN POSITIONS IN NATROLITE
Authors: Torrie B. H. , Brown I. D. , Petch H. E.
Published: April 2011

Neutron diffraction data obtained with single crystals of natrolite, Na2Al2Si3O10.2H20, have been analyzed using Fourier difference synthesis arid least squares methods. The details of the aluminosilicate framework were found to be in agreement with the results of earlier X-ray diffraction studies. The oxygen atom of the water molecule is linked by bent hydrogen bonds to two oxygen atoms in the framework, making an O—O—O angle of 134°. Lying almost in the O—O—O plane, the hydrogen atoms are located at distances of 0.94 ± 0.03 and 0.98 ± 0.02 Å from the oxygen of the water molecule and make with it an H—O—H angle of 108°. Natrolite thus provides an excellent example of the ability of the water molecule to resist the influence of the environment in opening the H—O—H angle.
SPECTRA AND STRUCTURES OF THE FREE HSiCl AND HSiBr RADICALS
Authors: Herzberg G. , Verma R. D.
Published: April 2011

Intense spectra of HSiCl and HSiBr in the region 6000 to 4100 Å have been obtained in the flash photolysis of SiH3Cl and SiH3Br, both in absorption and in fluorescence. They consist of progressions of bands with very wide K structures and very narrow J structures. A detailed fine structure analysis of these bands has been carried out and the geometrical structure of the molecules in both the upper and the lower states has been established. For the lower state, probably the ground state of HSiCl, it is found that[Formula: see text]and similarly for HSiBr[Formula: see text]In the excited states the angles are appreciably larger (see Table XI).A striking feature of the band structure in both HSiCl and HSiBr is the occurrence of branches of subbands with ΔK = ± 2, in addition to those with ΔK = ± 1 and 0, and furthermore, the presence of a subband with K = 0 in the branch with ΔK = 0. These anomalies can be accounted for by the assumption that the electronic transition is a triplet–singlet transition, more specifically 3A″–1A′ (or possibly 1A′–3A″). However, no triplet splitting has been resolved in the spectrum.
HIGH-LATITUDE BOUNDARY OF THE OUTER RADIATION ZONE AT 1000 KM
Authors: McDiarmid I. B. , Burrows J. R.
Published: April 2011

Particle detectors on the Alouette satellite have been used to determine the average high-latitude boundary of the outer radiation zone at 1000 km as a function of local time. The boundary for electrons with energies greater than 40 kev is approximately symmetrical with respect to the noon–midnight meridian and occurs at the highest latitude near local noon, shifting between 4° and 5° to its lowest value near local midnight. There is very little difference in the average boundaries of so-called trapped and precipitated electrons. The results are discussed in terms of measurements of electrons with similar energies in the equatorial plane and models of the earth's magnetic field.
ATMOSPHERIC WAVES FROM U.S.S.R. NUCLEAR TEST EXPLOSIONS IN 1962
Authors: Bhartendu  , Currie B. W.
Published: April 2011

Photographic reproductions of the records of the A1 wave systems at Saskatoon (52.1 °N., 106.6 °W.) from five nuclear test explosions in Novaya Zemlya during the summer of 1962 are given. Notable differences exist between some of the records. These may be due to differences in the heights of the explosions. Dispersion curves of group velocity against period are shown. Waves ranged in period from 6.0 to 0.8 minutes; group velocities from 275 to 313 m/sec.
RANGE OF ENERGETIC Xe125 IONS IN MONOCRYSTALLINE SILICON
Authors: Davies J. A. , Ball G. C. , Brown F. , Domeij B.
Published: April 2011

An electrochemical "peeling" technique for dissolving thin (40–600 Å) uniform layers from the surface of a silicon crystal has been developed and calibrated. Using this technique, range distributions of 5–80 kev Xe125 ions in monocrystal-line silicon have been measured as a function of the crystallographic direction. The ranges were found to depend strongly on the initial direction of ion motion, with the observed order being:[Formula: see text]These results for a diamond-type lattice are in qualitative agreement with the recent computer studies of Robinson and Oen (1963). Even for the least penetrating directions, the observed range is about three times the value expected in the absence of crystal lattice effects. At ion bombardments exceeding 1012 Xe+/cm2, the observed penetration decreased significantly; this sensitivity to rather low levels of ion bombardment suggests that bombardment induces a change in crystal structure.
RADIATION FROM SOURCES IMMERSED IN COMPRESSIBLE PLASMA MEDIA
Authors: Wait James R.
Published: April 2011

Boundary value problems involving dielectric and compressible plasma media are considered. The geometrical configurations are idealized to the extent that Maxwell's equations, when combined with continuum theory of fluid dynamics, are separable. The specific problems considered are motivated by a need to understand radiation of sources immersed in compressible isotropic ionized media. Various results for cold plasma configurations are recovered when the (electron) acoustic velocity is allowed to approach zero. Some attention is given to phenomena related to the resonance in the dielectric cavity which contains the sources. In particular, it is shown that the resonant conditions are modified appreciably by the finite compressibility of the surrounding plasma.
EFFET DES CHARGES D'ESPACE ÉLECTRONIQUES SUR LES COURBES DE PROBABILITÉ D'IONISATION DES GAZ
Authors: Marmet P.
Published: April 2011

In electron impact studies, the difference between the ideal ionization probability curve which would be obtained with monoenergetic electrons and the experimental curve produced with a certain energy distribution is usually interpreted using the Maxwellian distribution of thermally emitted electrons and assuming that the electronic space charge and accelerating potential do not modify the energy distribution. Several recent papers (e.g. Hartwig and Ulmer 1963) mention contrarily that there is a redistribution of energy after a relaxation time. It will be shown that the influence of this redistribution of energy on ionization efficiency curves is different for different ion sources. It devolves that several instrumental effects can be explained, and that the electron energy distribution cannot be simply deduced from the sharpness of the discontinuities in the ionization efficiency curve.
STUDIES IN THE ACTIVE DEPOSIT OF ACTINIUM: PART II: THE DECAY OF 211Pb (AcB)
Authors: Cothern C. R. , Connor R. D.
Published: April 2011

Studies of the active deposit of actinium using a Siegbahn–Slatis beta-ray spectrometer and scintillation counters together with gamma–gamma coincidence work and gamma–gamma angular correlation measurements have led to the establishment of a new decay scheme for 211Pb and a level scheme for 211Bi involving five excited states.The gamma rays have the following energies and absolute intensities:[Formula: see text]Conversion-line studies yielded energy values for the transitions marked with an asterisk as 403.3 ± 0.5 and 426.5 ± 0.5 keV respectively. The K conversion coefficients of the 400- and 430-keV transitions have been determined as 0.091 ± 0.018 and 0.117 ± 0.024 respectively.Fermi analysis yields 1.378 MeV as the highest end-point energy of the beta partial spectra. The remaining end points and the component intensities as deduced from the level scheme are as follows:[Formula: see text]The much less accurate results from Fermi analysis of the complete active deposit are in reasonable agreement with these data.Angular correlation studies of the 430–400- and 706–400-keV gamma-ray cascades have yielded spins for the levels concerned: ground level (9/2), 400-keV level (7/2), 830-keV level (9/2), and 1 100-keV level (7/2). These spins are the only ones consistent with the experimental evidence and the theoretical arguments presented.
A STUDY OF SUPERCONDUCTIVITY IN LEAD–BISMUTH ALLOYS USING ELECTRON TUNNELING TECHNIQUES
Authors: Adler J. G. , Ng S. C.
Published: April 2011

Some of the properties of superconducting lead–bismuth alloy films have been investigated using electron tunneling techniques. The superconducting energy gaps and transition temperatures as well as the effective tunneling density of electron states near the end point of the phonon spectrum have been measured for various compositions of this alloy system. It was found that pure bismuth films as well as bismuth films containing small amounts of lead are not superconducting above 1 °K. The results also indicate that for alloys with bismuth concentrations between about 35% and 75%, superconductivity is due partially to a proximity effect.
TRAJECTORY-COMPUTED VERTICAL THRESHOLD RIGIDITIES FOR 85 NEUTRON MONITOR STATIONS
Authors: Kodama M.
Published: April 2011

As an extension of the trajectory calculations for asymptotic directions of cosmic-ray particles done by Hatton and Carswell (1963), the vertical threshold rigidities for 85 cosmic-ray stations have been determined with an accuracy of 0.1 GV. It is shown that the differences of the new threshold rigidities from those of Quenby and Wenk are not negligibly small for particular stations, and also that they are fairly sensitive to the difference of the geomagnetic field simulation adopted for the computation. The new rigidities are evaluated by applying them to typical cosmic-ray-disturbance events throughout the last solar cycle, namely a Forbush decrease in July, 1959, and two solar-flare particle increases in February, 1956, and November, 1960.
TEMPERATURE DEPENDENCE OF THE PHOTOSENSITIVITY OF THE NON-SELF-MAINTAINED LOW-FREQUENCY ELECTRIC DISCHARGE AND THE JOSHI EFFECT IN HALOGENS
Authors: Venugopalan M.
Published: April 2011

The temperature dependence of the photosensitivity of an electric discharge with 50-cycle potentials in halogen-filled Siemens' tubes has been studied at constant gas pressure p as well as at constant mass conditions. The potential width of the photosensitive non-self-maintained region and the onset potentials of the self-maintained region of the discharge increased at constant p with the temperature T > 100 °C. In the self-maintained region of the discharge, irradiation by external light produced the familiar photoreduction of the discharge current i, viz. the negative Joshi effect, −Δi, which increased very little with T at constant p and applied potential V and reversed sign, depending on V, at 100–120 °C to the positive Joshi effect, +Δi, i.e., the photoincrease of i.Oscillographic studies of the current structure at [Formula: see text], the breakdown voltage in the dark, confirmed the co-occurrence of both +Δi and −Δi at T < 100 °C. They confirmed also that −Δi was absent at T > 100 °C. An integrating current detector which measured the resultant Δi showed that for a given p and T, +Δi increased with [Formula: see text] to a maximum; above Vm, +Δi decreased and reversed sign to −Δi as V was increased. At constant mass conditions, the Δi−V curve shifted towards the increasing potential axis by an increase in T. The potential at which +Δi was maximum and the potential at which the sign reversal of Δi occurred increased with T; the maximum magnitude of +Δi also increased with T > 100 °C.
A LARGE-VOLUME, COAXIAL, LITHIUM-DRIFT, GERMANIUM GAMMA-RAY SPECTROMETER
Authors: Malm H. L. , Tavendale A. J. , Fowler I. L.
Published: April 2011

A high-resolution, germanium p-i-n diode gamma-ray spectrometer has been made using the coaxial method of lithium drift. The detector described is ~ 16 cm3 in sensitive volume, three to four times that of the largest "planar" drifted diodes of this type described to date. Its performance as a spectrometer is comparable with that of smaller diodes; resolutions (fwhm) of 3.3 and 4.8 keV were obtained at γ-ray energies of 122 and 1 333 keV respectively with a detector bias of 1 000 to 1 500 V. Typical γ-ray spectra obtained with sources of 57Co, 60Co, 137Cs, and Th(B + C + C″) are shown. Also shown are curves of intrinsic full-energy peak efficiency over a range of energies. This efficiency is 2.5% at 1 300-keV γ-ray energy—comparable to that of a NaI scintillation spectrometer 1 in. in diameter by 1 in. long.
THE INITIAL CREEP OF COLUMNAR-GRAINED ICE: PART II. ANALYSIS
Authors: Gold L. W.
Published: April 2011

Observations on the initial creep behavior of columnar-grained ice are analyzed by assuming that the creep strain at a given time has a power-law dependence on the applied constant compressive stress. The exponent for the stress was time-dependent during transient creep. For first load it started at a low value, increased to a maximum of about 2.23 approximately 75 minutes after the application of the load, and decreased thereafter. For reload it started at a high value and decreased continuously to a constant value of 1.46 by 100 minutes after the application of the load. Creep rates at a given time, calculated from the observed power-law dependence of the creep strain on stress, also had a power-law dependence on stress for time greater than about 25 minutes after the application of the load. The observations are shown to be in agreement with observations by Krausz (1963) on the deflection rate of ice beams and by Steine-mann (1954) and Glen (1958) on the stress-dependence of the minimum creep rate during secondary creep. The observations indicate that the creep rate during secondary creep varies approximately as t−0.5.
SIZE-DEPENDENT ERRORS IN Z DETERMINATION USING THE HARMAN METHOD
Authors: Champness C. H. , Parekh P. C.
Published: April 2011

The effect of sample size on the measured thermoelectric figure of merit (Zm) determined by the Peltier–Seebeck or Harman method has been studied by progressively halving the area (As) and length (ls) of bismuth telluride alloy samples. Measurements were carried out with As values from 1 to 0.01 cm2, la values from 2 to 0.5 cm, and three different gauges of current leads (cross-sectional area Aw). The relative decrease of Zm was found to vary approximately as sech [Formula: see text] with Aw and ls constant, as In Aw with As and ls constant, and as T4/s2 with Aw and As constant, where T is the absolute temperature. The variation with As and Aw appears to be due to conduction along the sample leads, while the variation with ls is well accounted for by radiation to and from the sample. With 40 A.W.G. wires, the error in the measured figure of merit is estimated to be about 5% for a sample of dimensions 0.5 × 0.5 × 1 cm and around 50% for a sample of size 0.1 × 0.1 × 2 cm.
A DETERMINATION OF THE INTERMOLECULAR POTENTIAL PARAMETERS OF THE INERT GAS SOLIDS FOR THE MODIFIED BUCKINGHAM EXP–6 POTENTIAL
Authors: Brown J. S.
Published: April 2011

The intermolecular potential parameters of solid Ne, Ar, Kr, and Xe are calculated for a modified Buckingham exp–6 potential using crystal data of the sublimation energy and lattice spacing extrapolated to 0 °K. The parameters ε and σ in the exp–6 potential[Formula: see text]are compared for selected AN ("all neighbor") models with those calculated by Mason and Rice (1954) from gaseous data.
INVESTIGATION OF NOISE SIGNALS IN PULSED DISCHARGE DEVICES
Authors: Medley S. S. , Curzon F. L. , Daughney C. C.
Published: April 2011

The mechanisms responsible for emission of electromagnetic noise signals by pulsed discharge circuits have been studied. The investigation has led to an improved discharge system which minimizes the production of noise signals through the use of a photon-triggered pulse generator and coaxial or parallel plate current-carrying leads. The residual noise signals are due principally to the spark-gap switches required in the discharge system. The discharge current in the improved system is measured with a simple and inexpensive Rogowski coil apparatus into which delay lines are incorporated. This measuring apparatus provides oscillograms of the discharge current that are completely noise free, and obviates the use of costly isolation transformers and screened rooms for producing clean oscillograms. The frequency response of the measuring apparatus is flat to 5 Mc and 3 dB down at 7 Mc.
SCINTILLATION DECAY IN CALCIUM TUNGSTATE
Authors: Sayer M. , Hardy W. R.
Published: April 2011

Measurements of the luminescence decay time have been made for a number of single crystals of calcium tungstate for excitation by cathode rays, α and γ radiation. The value of the decay time was found to depend both on the crystal used and on the nature of the excitation. For γ-ray excitation, the decay time was in the range 6.1 to 6.8 μ sec. The values obtained for cathode-ray excitation were, in general, 20–30% higher for all crystals, while for α excitation, several crystals showed no change in decay time, while others showed a decay time 20% faster. Measurements of the temperature dependence of the decay time and thermoluminescence experiments indicate that these differences in behavior can be attributed to differences in the density of energy traps and nonradiative centers in the crystal and to a rise in temperature in the excited channel.
THE NONLINEAR INTERACTION OF A RADIO-FREQUENCY WAVE WITH AN INHOMOGENEOUS PLASMA SLAB: I. KINETICS OF HIGH-TEMPERATURE AIR IN THE PRESENCE OF AN ELECTROMAGNETIC FIELD
Authors: Papa Robert J. , Case Carl T.
Published: April 2011

A radio-frequency wave is normally incident upon an inhomogeneous plasma slab. The plasma slab is composed of partially ionized high-temperature air corresponding to the characteristics of the plasma sheath surrounding hypersonic reentry vehicles. The isotropic part of the electron velocity distribution function is Maxwellian because of electron–electron collisions. The electromagnetic wave is intense enough to heat selectively the electron gas, altering the various electron production and loss processes. The high-frequency limit is considered, and expressions are obtained for the electron number density and effective collision frequency as a function of electron temperature. The effective collision frequency takes into account the effects of electron–neutral and electron–ion collisions for momentum transfer. From an energy balance equation, the electron temperature is found to be a function of both the frequency and field strength of the wave. The electron temperature is found also to exhibit an instability that gives rise to a hysteresis effect.
COMPOSITION OF MATTER IN NUCLEAR STATISTICAL EQUILIBRIUM AT HIGH DENSITIES
Authors: Tsuruta Sachiko , Cameron A. G. W.
Published: April 2011

Various properties of dense matter in nuclear statistical equilibrium are studied for densities and temperatures in the range [Formula: see text] and [Formula: see text]. With increasing density the stability shifts to more and more neutron-rich nuclei. With increasing temperature the general tendency is that nuclei of smaller charge become more abundant, and the abundances of nuclei near a peak tend to become nearly as large as that of the peak nucleus. The shifting of the most stable region with change of density or temperature takes place rather abruptly from one neutron closed shell region to the next. For densities [Formula: see text], the ordinary iron group nuclei are most stable until the temperature becomes about 5 × 109 °K; for higher temperatures matter in equilibrium consists of almost pure helium. For higher density, this transition to a helium phase takes place at a somewhat higher temperature, and the equilibrium configuration for temperatures below the helium transition point shifts to the neutron-rich side of the valley of beta stability. When [Formula: see text], matter consists of almost pure neutrons at all densities. Rates of beta reactions and neutrino emission generally increase with increase of density and temperature. At a typical temperature of about 5 × 109 °K, the neutrino energy emission rate increases from about 2 × 1011 ergs/g sec at ρ ~ 106 g/cm3 to about 2 × 1017 erg/g sec at ρ ~ 3 × 1011 g/cm3.
THE ANGULAR DISTRIBUTION OF 5.6-MeV GAMMA RAYS FROM THE CAPTURE BY 124Sn OF 62-eV NEUTRONS
Authors: McNeill K. G. , McConnell D. B. , Firk F. W. K.
Published: April 2011

Angular distribution measurements have been made on the near-ground-state gamma-ray transitions from the state in 125Sn excited by the capture by 124Sn of 62-eV neutrons. The distribution is essentially isotropic. In conjunction with other evidence, it is concluded that the capturing state is a p 1/2 state.
DETECTING MICROMETEOROIDS ACOUSTICALLY FROM ROCKETS
Authors: Wlochowicz R.
Published: April 2011

Two models of acoustic micrometeoroid detectors were flown piggyback on several Canadian rockets, one of which was launched in the spring of 1963 and the others in the winter and fall of 1964 from the Churchill Rocket Range. The micrometeoroid detecting systems and the calibration technique based on the elastic impact of polystyrene spheres are described. The detector response is found to be proportional to m0.8ν1.1. Responses recorded during six flights are presented and analyzed. The analysis is developed in detail to illustrate the uncertainties in interpreting the data and to establish qualitatively the accuracy of the results. Responses attributed to impacts of micrometeoroids are treated collectively. An average impact rate of 1.4/m2 sec and a threshold mass of 10−11 g at 30 km/sec are ascribed to the data. A high density of small particles is apparently indicated. Impact rates for successive 5-km intervals to a height of 167 km indicate a variation with height. Regions of increased activity, roughly double the average rate, are observed centered on the height intervals 145 to 150 km and 125 to 130 km. A region of slightly less activity exists near 90 km, and a sharply defined region appears at the 105 to 110 km interval. The relative stability of all or any of these active regions has yet to be established.
THERMONUCLEAR REACTIONS IN MEDIUM AND HEAVY NUCLEI
Authors: Truran J. W. , Hansen C. J. , Cameron A. G. W. , Gilbert A.
Published: April 2011

A method is outlined by which thermonuclear reaction rates can be determined from the statistical properties of nuclei. Assuming that the contribution to the cross section of a given resonance is given by the Breit–Wigner single-level formula, the total rate is determined by integrating the product of the cross section, weighted by the nuclear level density, and the velocity over energy. The nuclear radiation widths were calculated on the assumption that electric-dipole transitions are dominant. The particle widths were determined by approximating the nuclear strength function by that value calculated for a black nucleus. Nuclear cross sections calculated in this manner are compared with experiment both for charged-particle reactions on lighter nuclei and for neutron-capture reactions proceeding on nuclei in the mass range A > 60. Good agreement is obtained in both cases.
THE ELECTRONIC EMISSION SPECTRUM AND MOLECULAR CONSTANTS OF IODINE MONOFLUORIDE
Authors: Durie R. A.
Published: April 2011

Observation by the author (Durie 1951) of a well-developed band system in the emission from an iodine–fluorine flame provided the first evidence for the existence of iodine monofluoride (IF), the last of the six possible diatomic inter-halogen compounds to be detected. The spectrum, which lies in the region 4 300 to 7 600 Å, has since been photographed under high resolution using a 21-ft concave grating spectrograph. The rotational structure of the bands is shown to be consistent with an A3Π0+ → X1Σ transition in the IF molecule. A rotational and vibrational analysis of the bands has been carried out and the molecular constants evaluated for IF. The results are as follows:[Formula: see text]The present evidence relating to the value of the dissociation energy of IF is discussed.
THE LAW OF CORRESPONDING STATES AND COLD NEUTRON SCATTERING BY LIQUIDS
Authors: Sears V. F.
Published: April 2011

Although the law of corresponding states can be used in the practical analysis of cold neutron scattering data from liquids only if quantum effects are negligible, it is of interest, nevertheless, to have a quantum mechanical derivation of this law, because it is only then that one can discuss, in a completely consistent way, the conditions under which quantum effects are negligible. Such a derivation is given in the present paper. We also present an extension of the law of corresponding states to the velocity spectrum of an atom in a simple liquid and indicate how this can be used to check the consistency and extend the range of applicability of theoretical models of the velocity spectrum.
AN INTERMEDIATE DONOR LEVEL IN N-TYPE GALLIUM ARSENIDE
Authors: Basinski J.
Published: April 2011

The activation energy and corresponding concentration of an unknown donor level in high-mobility n-type gallium arsenide has been determined. The energy and concentration have been found by fitting a suitable theoretical expression to results of Hall Effect measurements in the range 77–360 °K. The energy found is 0.158 eV below the conduction band.
THE GRAVITOKINETIC FIELD AND THE ORBIT OF MERCURY
Authors: Scott J. C. W.
Published: April 2011

A new Lorentz-invariant gravitational field theory is introduced according to which space–time is always flat. The gravitational field is of Maxwellian form with potential and kinetic components analogous to the electric and magnetic components of the electromagnetic field. New mathematical entities named scaled tensors are developed. While the electromagnetic force is represented by an unsealed tensor, the gravitational force is properly described by a scaled tensor. The precession of the orbit of the planet Mercury establishes the scale of the gravitational force as −5. Since the force on a body is found to be proportional to its total mass, the null results of Eötvös and Dicke are confirmed. However, the theory requires that the force depend on velocity so that new very small effects analogous to electromagnetic phenomena are predicted. In a following paper, "Photons in the Gravitational Field", the gravitational red shift and the gravitational deflection of a light ray are deduced correctly.
A GROUP-THEORETICAL TREATMENT OF VIBRATIONAL, TORSIONAL, AND ROTATIONAL MOTIONS IN CH3—C≡C—SiH3
Authors: Hougen Jon T.
Published: April 2011

A set of coordinates is described for methylsilylacetylene which allows a separation of the molecular wave function into a vibrational part, a torsional part, and a rotational part. The transformation properties of these coordinates, and vibrational, torsional, or rotational wave functions containing them, are discussed in terms of a double group of the molecular symmetry group appropriate for the classification of the overall wave functions of the molecule. Particular attention is given to the symmetry properties of vibrational symmetry coordinates and normal modes, since these symmetry properties are rather different from those encountered in molecules without free internal rotation. An exact and an approximate rotational–torsional–vibrational kinetic-energy operator is derived. Selection rules on symmetry species and also on angular-momentum quantum numbers are presented for electric dipole transitions.
THEORY OF COLD NEUTRON SCATTERING BY HOMONUCLEAR DIATOMIC LIQUIDS: II. HINDERED ROTATION
Authors: Sears V. F.
Published: April 2011

The partial wave expansion of the cold neutron scattering cross section for a homonuclear diatomic liquid in terms of the angular momentum transfer, which was introduced in a previous article for the case of free rotation, is generalized to include hindered rotation. The cross section is expressed in terms of an orientational distribution function that is the rotational analogue of the Van Hove self-correlation function. The rotational scattering function for the lth partial wave is shown to be the Fourier transform of a rotational relaxation function, Fl(t), which is also the lth coefficient of the expansion of the orientational distribution function in terms of spherical harmonics. The functions Fl(t) are calculated for the limiting cases of free rotation and rotational diffusion. The problem of neutron diffraction by homonuclear diatomic liquids is also investigated, and it is shown that the small angle scattering is determined by the isothermal compressibility. This is a generalization of the well-known result for monatomic liquids.
FLUORESCENCE, DEFECT FLUORESCENCE, AND PHOSPHORESCENCE SPECTRA AT 4.2 °K OF UNDOPED AND β-METHYLNAPHTHALENE-DOPED NAPHTHALENE CRYSTALS
Authors: Lipsett F. R. , Macpherson G.
Published: April 2011

Fluorescence, defect fluorescence, and phosphorescence spectra were obtained at 4.2 °K from undoped crystals containing unwanted impurities and from crystals deliberately doped with β-methylnaphthalene. The doped crystals included normal and fully deuterated naphthalene and β-methylnaphthalene in all combinations. Fluorescence attributable to physical defects, analogous to that recently reported for anthracene, was found in all crystals. This fluorescence consisted of bands rather than lines, and occurred in the spectral region between fluorescence (singlet emission) and phosphorescence (triplet emission). The excitation spectrum (intensity of the fluorescence as a function of excitation wavelength) showed one of two forms depending on the fluorescence band chosen, which indicated that the defect fluorescence may be excited either directly or by energy transfer, similarly to other modes of luminescence. The decay time of the defect fluorescence was < 0.01 second, indicating that the defect states are probably disturbed naphthalene singlet states.Moderately intense phosphorescence consisting of lines was found in all of the doped crystals. Assignments of the lines could not be made because of the large number of lines present. However, probable values of the triplet 0–0 levels of normal and deuterated naphthalene and β-methylnaphthalene were deduced from the present and related experiments. The undoped crystals showed a few very weak phosphorescence lines superimposed on a weak continuum of fluorescence. Those crystals with the fewest lines were the purest, and showed a decay time of line plus continuum < 0.01 second, confirming that pure naphthalene is not phosphorescent at 4.2 °K. Phosphorescence excitation spectra, decay times, and temperature dependences were found. For the doped crystals, the decay times ranged from < 0.01 to 18 seconds and the phosphorescence intensity at 10–12 °K fell to half the value at 4.2 °K, indicating an activation energy of about 37 cm−1. The phosphorescence excitation spectrum, decay time, and temperature dependence of naphthalene-d8 doped with β-methylnaphthalene were dissimilar to those of the other doped crystals, for reasons which are not yet understood.The fluorescence spectra consisted of lines for both undoped and doped crystals. The results were tabulated and compared with those of other research workers. It was not possible, however, to assign each line, to either a particular material or a particular vibrational mode.
THEORY OF THE SPIN-LATTICE INTERACTION IN PARAMAGNETIC SALTS OF IRON-GROUP IONS
Authors: Kranendonk J. Van , Lee Y. Y.
Published: April 2011

The form of the spin-lattice coupling in hydrated salts of the iron-group ions is derived in terms of the lattice vibrational coordinates and the effective spin variable, using general symmetry arguments. The most important coupling terms for octahedral and spherical symmetry are given, and the role of the breathing and rotational modes is discussed, as well as the concept of adiabatic and non-adiabatic coupling. This work forms the basis of the semiclassical theory of phonon radiation processes and phonon multipole fields and interactions to be presented in a subsequent paper. Finally, explicit expressions for the coupling constants in terms of the electronic structure of the ions are also derived, for the case of a nondegenerate ground orbital level.
NEUTRON POTENTIALS FOR NUCLEI IN AN ISOTOPIC SEQUENCE
Authors: Sood P. C. , Sood N. K.
Published: April 2011

The shell model and the optical model potentials over wide ranges of nuclei can be represented satisfactorily as V0 ± V1 (N − Z)/A, the plus sign corresponding to the proton potential and the minus to the neutron potential. The proton potentials for nuclei in an isotopic sequence agree with the above expression, but the corresponding neutron potentials are found to deviate. The deviations are attributed to the departures from the line of beta stability, and it is suggested that the neutron potentials for these cases should be represented by the expression[Formula: see text]Nst being determined from the semiempirical mass formula. The results for Sn isotopes are cited illustrate the phenomenon.
ON THE FERMI SURFACE OF BETA BRASS
Authors: Jan J. -P.
Published: April 2011

Results of de Haas – van Alphen effect measurements on ordered β′-CuZn (50 at.% Zn) provide the area of contact of the Fermi surface with the faces of the second (dodecahedral) Brillouin zone. If the energy gaps at the faces of the first (cubic) Brillouin zone are ignored, a 12-cone model can be worked out. An energy gap of 3.49 eV at the second-zone faces and an effective mass m* = 1.045me, provide the best fit between the 12-cone model, the area of contact, and the measured electronic specific heat. The gap is in good agreement with present band-structure calculations. The first-zone gaps do give rise to de Haas – van Alphen oscillations, but their neglect in the present model should not affect the calculated electronic specific heat appreciably.