bluuebunny/crossref_metadata_2025 huggingface dataset:
AN EMISSION SYSTEM OF THE IO MOLECULE
Authors: Durie R. A. , Legay F. , Ramsay D. A.
Published: April 2011

The "methyl iodide flame bands", lying in the region 4100 to 6300 Å, have been photographed using a 21-ft concave grating spectrograph. The bands are shown to arise from an A2Π → X2Π transition of the IO molecule. Rotational and vibrational analysis of the bands has been carried out and the molecular constants of IO obtained.
SPIN–LATTICE RELAXATION EFFECTS OBSERVED IN THE CONTINUOUS POWER SATURATION OF PARAMAGNETIC LINES
Authors: Marr G. V. , Swarup Prem
Published: April 2011

The dependence of the conventional saturation parameter on the incident microwave power is considered for Lorentzian-shaped paramagnetic lines and applied to a study of the [Formula: see text] transitions of Cr+++ in K3Co(CN)6 and Gd+++ in La(C2H5SO4)3∙9H2O at 9 kMc/sec and 4.2 °K. It is shown that the experimental observations may be explained on the basis of a spin–lattice transition probability which depends on spin–photon interactions. Values of the effective spin–lattice relaxation times are compared with pulse technique determinations and estimates of the corresponding phonon relaxation times are also given.
SPIN LATTICE RELAXATION IN NEODYMIUM ETHYLSULPHATE AT LIQUID HELIUM TEMPERATURES
Authors: Daniels J. M. , Rieckhoff K. E.
Published: April 2011

The optical Faraday effect was used to measure instantaneous magnetization in neodymium ethylsulphate. The spin populations were disturbed by pulses of microwave power, and by adiabatic magnetization and demagnetization, and the approach to equilibrium was studied. The relaxation was found to be exponential and spin lattice relaxation times were measured, for temperatures between 1.3° K and 4.2° K, and for magnetic fields between 80 and 6000 oersted. The relaxation time was found to decrease with increasing magnetic field, and to vary with temperature approximately as 1/T3. No dependence of relaxation time on pulse length was found.
TRANSISTORIZED POWER SUPPLIES FOR A MASS SPECTROMETER
Authors: Russell R. D. , Kollar Frank
Published: April 2011

While a mass spectrometer itself may require a few hundred watts of regulated power for the magnet and only a few watts of regulated power for all other purposes, the regulating supplies often dissipate kilowatts. The construction of more efficient supplies using transistors and magnetic amplifiers results in substantial savings in the physical size of the supplies, the cost of their component parts, and the effort required for maintenance.Circuits and descriptions are presented for a magnet current power supply and a filament emission control that have been used in the mass spectrometer built recently at this laboratory. These illustrate the simplicity possible with transistor-regulated supplies, as well as the savings mentioned above. The mass spectrometer is a 12-in. radius 90° instrument used at mass 250 with a 5000-volt accelerating voltage. The magnet, which supplies a field of more than 5000 gauss over an area of 800 cm2 and across a gap of 1.9 cm, and which weighs three quarters of a ton, is supplied from a regulated supply dissipating about 50 watts. The filament emission control takes about 30 watts from the mains.
HIGH-ALTITUDE COSMIC RAY MEASUREMENTS AT FORT CHURCHILL
Authors: McDiarmid I. B. , Rose D. C.
Published: April 2011

Measurements with rocket-borne Geiger counters have been carried out at altitudes up to 250 km at Fort Churchill, Manitoba. The total primary cosmic ray intensity at a time near a solar maximum has been determined and compared with other measurements taken at times of high solar activity and also with other Geiger counter measurements obtained near a solar minimum. A low-energy radiation was observed whose intensity increased with altitude up to about 25% of the primary intensity at 250 km.
SOME OXYGEN IONS FORMED AT HIGH PRESSURES IN A MASS SPECTROMETER
Authors: McGowan Wm. , Kerwin Larkin
Published: April 2011

The oxygen ions formed by electron bombardment and collision processes in the mass spectrometer at pressures of about 10−3 mm Hg are examined. Mass spectrum lines due to O+, [Formula: see text], [Formula: see text], and O++ as well as Aston bands due to O+, [Formula: see text], and [Formula: see text] are found. Processes leading to these species, as well as abundances and appearance potentials, are considered.
MEAN LIVES OF POSITRONS IN ALUMINUM AND THE ALKALI METALS
Authors: Jørgensen M. H. , Bell R. E.
Published: April 2011

The time distribution of positron annihilations in the metals aluminum, lithium, sodium, potassium, and cesium have been measured with a fast time-to-amplitude converter. The decay curves appear to be complex, with about 5% of the events having a mean life of approximately 5×10−10 sec. The main (95%) components of the decay curves show the following mean lives, in units of 10−10 sec: Al, 1.9 ± 0.2; Li, 2.9 ± 0.2; Na, 3.15 ± 0.2; K, 4.0 ± 0.2; Cs, 4.3 ± 0.2. The results for the alkali metals disagree with the previously published measurements of De Benedetti and Richings (1952). These results are discussed, and the lifetimes for other metals are predicted roughly from them and from the angular correlation measurements of other workers.
AN HYPOTHESIS CONCERNING TURBULENT DIFFUSION
Authors: Bourret R.
Published: April 2011

It is shown that the Goldstein equation for turbulent diffusion implies diffusion currents dependent upon the history of the concentration gradient. An analysis of the stochastic model upon which the Goldstein equation is based reveals that the hereditary function, by which the history is weighted, is the ensemble autocorrelation function of velocity. Heuristic arguments and an appeal to the theory of irreversible thermodynamic processes lead to the postulation of an integro-differential equation for turbulent diffusion involving the velocity autocorrelations of the diffusate particles.
SPECTROSCOPIC TEMPERATURE MEASUREMENTS IN A SHOCK TUBE USING CN AS A THERMOMETRIC MOLECULE
Authors: Parkinson W. H. , Nicholls R. W.
Published: April 2011

Rotational intensity measurements on the CN spectrum, excited through shock excitation of a powdered mixture of NH4Cl, KNO2, and C by helium-driven shock waves in argon have been used to infer "rotational temperatures" of the gas between 6350 °K and 8750 °K. The measured values agree well with gas kinetic temperatures inferred from simple gas dynamic theory and shock-wave velocity measurements.
THE THERMAL NEUTRON CAPTURE CROSS SECTION AND RESONANCE CAPTURE INTEGRAL OF PROTACTINIUM-233
Authors: Eastwood T. A. , Werner R. D.
Published: April 2011

The thermal neutron capture cross section and resonance capture integral of Pa233 to form the 1.2-minute and 6.7-hour isomeric states of Pa234 have been measured using activation methods. The results are as follows:[Formula: see text]Irradiations made with different thicknesses of cadmium cover show the absence of a major resonance for the formation of the 6.7-hour state in the region of the cadmium cutoff. The results are compared with earlier values and some reasons for discrepancies have been studied experimentally.
THE DISTRIBUTION OF RADIO-AURORA IN CENTRAL CANADA
Authors: Forsyth P. A. , Green F. D. , Mah W.
Published: April 2011

Five bistatic v.h.f. radio systems were operated in central Canada during the I.G.Y. for the purpose of detecting auroral ionization. Consistent records were obtained for a period of 5 months and these records have now been analyzed. Two types of events were detected. The nighttime (A) events occur most frequently in the auroral zone and characteristically are observed simultaneously at two points separated by about 300 kilometers. The daytime (5) events occur simultaneously over a much larger area. The time of maximum occurrence of A events becomes later with decreasing latitude whereas the reverse is true for S events. The variation with latitude of the occurrence of A events is similar to that of other auroral phenomena.
THE GROUP VELOCITY OF PLANE SURFACE WAVES
Authors: Mungall A. G. , Morris D.
Published: April 2011

The velocity of transmission of a modulated microwave signal over a dielectric-covered plane conductor has been measured over a range of dielectric thicknesses for which the first order TM surface wave mode is known to propagate. An exact theoretical treatment of plane surface wave group velocity for both TM and TE surface wave modes of any order has been developed and calculations carried out for the first two orders. The experimentally determined signal velocities are in good agreement with the group velocities calculated for the first order TM mode. Effects of possible surface wave propagation on the accuracy of microwave distance-measuring methods are discussed.
AN ABSOLUTE MEASUREMENT OF THE ACCELERATION DUE TO GRAVITY AT OTTAWA
Authors: Preston-Thomas H. , Turnbull L. G. , Green E. , Dauphinee T. M. , Kalra S. N.
Published: April 2011

An apparatus for determining the absolute value of gravity by measuring the distances through which a rule falls in discrete time intervals is described. From the data associated with 64 drops with two non-magnetic stainless steel rules in vacuum, a value of g at the absolute gravity station at Ottawa of 980.6132 cm sec−2 with a possible error of ± 0.0015 cm sec−2 has been obtained. This value is 13.7 ± 2.0 milligal less than the Potsdam value at that position.
CONCENTRATION OF PARTICULATE AIR-BORNE FISSION PRODUCTS AT GROUND LEVEL IN CANADA DURING I.G.Y.
Authors: Wolfson J. L. , Terentiuk F.
Published: April 2011

Daily measurements are reported of the concentration of air-borne fission products at ground level in Canada during the period from late 1957 to the end of March 1959. The measurements, conducted at 14 stations throughout Canada, were part of the Canadian program for the International Geophysical Year and International Geophysical Co-operation. The results are given in the form of charts for each of the 14 stations, and monthly averages for each of the stations are tabulated.
HALF-PERIOD OF Th232
Authors: Farley Thomas A.
Published: April 2011

A redetermination of the half-period of Th232 by ion chamber alpha particle spectroscopy has been made. It was originally undertaken to check the possibility that an error in the half-period of Th232 is responsible for discrepancies in geological ages of rocks determined from Th/Pb ratios as compared with ages determined from U/Pb ratios. A gridded, pressurized, 2 pi geometry ion chamber using an argon–methane counting gas was used as a detector for alpha particles emitted from thin layers of metallic thorium evaporated onto glass plates. The counting rate under the Th232 alpha peak was measured with a 256-channel pulse height analyzer, and corrections of about 1% were made for self-absorption and backscatter by the glass plate and counting gas. The samples were chemically analyzed for thorium content by a spectrophotometric method. The average half-period for 12 samples is [Formula: see text] years, with a standard error of 1%. The result is in substantial agreement with the half-periods of greater uncertainty already reported in the literature, and geological age discrepancies cannot be attributed to error in the half-period of Th232.
CELL TO DENDRITE TRANSITION IN TIN BASE ALLOYS
Authors: Plaskett T. S. , Winegard W. C.
Published: April 2011

The transition from cellular growth to dendritic growth was investigated for dilute binary alloys of zone-refined tin with lead, bismuth, and antimony in terms of the rate of growth R, the temperature gradient in the liquid ahead of the solid-liquid interface G, and the solute concentration C0. It was found that a previous relationship describing the transition for lead base alloys applied, at least to a first approximation, for the low solute concentration tin results. At the high concentrations of solute, however, it was necessary to introduce another variable, namely the cell size at transition dt. The transition relationships only applied for alloy systems with a distribution coefficient k0, less than unity. For systems with k0 > 1 (antimony in tin) a k0 < 1 was used which was equivalent to the k0 > 1. A method is described for determining this "equivalent k0".
A THEORY OF IONOSPHERIC CURRENTS ASSOCIATED WITH AURORAE. II
Authors: Weaver J. T. , Skinner R.
Published: April 2011

The average ionospheric current flowing along a long homogeneous arc, is calculated numerically on the basis of the theory developed in Part I. This is compared with the auroral current necessary to produce the observed magnetic disturbance at Saskatoon (52.1 °N., 106.6 °W.) and Flin Flon (54.7 °N., 102.0 °W.) for an arc which satisfies the conditions required by the theory. A good order of magnitude agreement between the two values is obtained.The theory also shows that, in general, the magnitude of the line current is proportional to the intensity of the arc, but that when the ionospheric wind is directed along the arc, the line current vanishes. Thus a simple explanation of the occurrence of arcs with no associated magnetic disturbance is provided.A relationship between the average magnetic disturbance due to arcs and the ionospheric wind velocity is also established. The hourly variation of magnetic disturbance during aurorally active hours at Saskatoon and Flin Flon is shown to predict ionospheric wind velocity variations which agree well with those obtained by radio measurements.
A LOW TEMPERATURE STANDARD OF TOTAL RADIATION
Authors: Bedford R. E.
Published: April 2011

A standard of total radiation used for the calibration of thermal radiation detectors is described. The black body source is a modified cone operating over the temperature range 40 °C to 150 °C; the detector is located in an isothermal (better than 0.01 °C) environment. For the detectors used a decrease in sensitivity of approximately 1% during the first 24 hours was observed. This is probably due to the slow drying of the receiver surface by the gas used to displace the air. The day-to-day reproducibility of results is about 0.1%, and an over-all accuracy of 0.3% is claimed for radiation measurements made with the instrument. The scale of total radiation defined by four National Bureau of Standards carbon filament standards of thermal radiation probably differs from that defined here by −0.3%.
THE RAMAN SPECTRUM OF METHANE
Authors: Thomas M. A. , Welsh H. L.
Published: April 2011

The Raman spectrum of CH4 was obtained with a spectral resolution of ~0.3 cm−1, and rotational analyses of the ν and ν2 bands were carried out. The B0 values obtained from the ν2 and ν3 bands are 5.240 ± 0.002 and 5.2406 ± 0.0011 cm−1, respectively; the value of ν0 determined from the latter is 1.09403 ± 0.00016 Å. The rotational levels of the ν = 1 state of ν2 are double with B1 values of 5.313 and 5.379 cm−1. The rotational levels of the ν = 1 state of ν2 do not follow the theoretical formulae exactly; the deviations for the 13 branches observed can be expressed by using three different B1 values, 5.178, 5.195, and 5.212 cm−1. The value of ζ3 is 0.054. The band origins are: ν1 = 2916.7, ν2 = 1533.6, and ν3 = 3018.9 cm−1.
RELAXATION IN RUBY
Authors: Armstrong R. A. , Szabo A.
Published: April 2011

The relaxation of the (1↔2) and (2↔3) transitions in chrome-doped Al2O3 (0.015%) has been studied at S-band, using a pulsed microwave method, over a range of crystal orientations in the magnetic field at temperatures of 77 deg;K to 50 deg;K, and at 4.2 deg;K and 1.6 deg;K. A T−7 variation of the relaxation time with temperature was found in the liquid nitrogen range. The relaxation time in this temperature range was found to be independent of crystal orientation, and for the (1↔2) transition was 50 microseconds at 77 deg;K. At liquid helium temperatures, harmonic cross relaxation was present over most of the range of the crystal orientation studied and was observed at harmonic-to-signal frequency ratios of 2:1, 3:2, and 1:2. The harmonic cross relaxation times were typically 10 to 100 times shorter than the lattice relaxation times, and were independent of temperature. At non-harmonic points at 4.2 deg;K, the spin–lattice relaxation could be described by one time constant, a value of 300 milliseconds being typical. At harmonic points anomalously long relaxation times as high as 12 seconds were observed.
ON THE STUDY OF DIFFUSION USING SPIN ECHOES
Authors: Muller B. , Bloom M.
Published: April 2011

The decay of the primary spin echo due to diffusion is governed by the expression [Formula: see text]. This statement is independent of the angles through which the magnetization is rotated by the radio frequency (r-f.) pulses. For the usual range of experimental values, it is also independent of the intensity or homogeneity of the r-f. field, the duration of the r-f. pulse, and the magnitude of the constant field gradient.
BULK PHOTOEFFECTS IN INHOMOGENEOUS SEMICONDUCTORS
Authors: Cox C. D.
Published: April 2011

A photoelectromotive force is observed when a semiconductor is illuminated in the region of a bulk inhomogeneity. A theoretical expression for the bulk photo-e.m.f. is derived which is valid for all levels of illumination in the region of an arbitrary impurity density gradient. With appropriate approximations the complete expression is simplified for the cases of weak and saturation illumination in inhomogeneous extrinsic and nearly intrinsic semiconductors, and in p–n and l–h junctions. The theoretical relation between bulk photo-e.m.f. and photoconductive resistance decrease is examined.Bulk photo-e.m.f. measurements were made on inhomogeneous germanium filaments. These showed the photo-e.m.f. to be linear with weak light illumination. Strong illumination photo-e.m.f. was shown to depend on the impurity distributions adjacent to the illuminated regions. The ratio of bulk photo-e.m.f. to photoconductive resistance decrease was constant at weak illumination in agreement with the theory. Measurements of the photo-e.m.f. as a function of temperature showed a close agreement with the predicted behavior in the near intrinsic range of conductivity.
TEMPERATURE DEPENDENCE OF THE PURE NUCLEAR QUADRUPOLE RESONANCE FREQUENCY IN KClO3
Authors: Vanier J.
Published: April 2011

The resonant frequency of the Cl35 nuclear quadrupole in KClO3 has been measured as a function of temperature in the range 15 deg;K to 77 deg;K; previous work between 77 deg;K and room temperature has been confirmed. Comparison has been made with Bayer's theory based on lattice vibrations and agreement is excellent. The ratio of the quadrupole coupling constant eQqzz of the two isotopes (Cl35 and CI37) has been measured at room and liquid air temperatures; significant changes have been observed in the measurements. Finally the possibility of using this temperature dependence as the basis of a sensitive thermometer has been studied; the accuracy of such a thermometer would be ±0.005 deg;K at 60 deg;K and ±0.05 deg;K at 20 deg;K.
EXPONENTIAL TRANSFER AND DIFFUSION
Authors: Rabinovitch W.
Published: April 2011

The one-dimensional heat equation is solved for exponentially decaying rate of increment and decrement of temperature at the surface of a semi-infinite medium.The diffusion equation is solved for exponentially decaying rate of transfer from a source to a diffusion medium. The two types of sources are: mass initially (a) located at a point, and (b) distributed at interfaces within a porous rectangular parallelepiped or sphere. Solutions for subsequent concentration distribution are stated, and compared with the well-known cases of instantaneous transfer. Numerical evaluation is afforded by the probability integral of complex argument. The treatment is applicable to cases of first-order irreversible chemical reaction and simultaneous diffusion of reaction products.
INTERNAL ATMOSPHERIC GRAVITY WAVES AT IONOSPHERIC HEIGHTS
Authors: Hines C. O.
Published: April 2011

Irregularities and irregular motions in the upper atmosphere have been detected and studied by a variety of techniques during recent years, but their proper interpretation has yet to be established. It is shown here that many or most of the observational data may be interpreted on the basis of a single physical mechanism, namely, internal atmospheric gravity waves.A comprehensive picture is envisaged for the motions normally encountered, in which a spectrum of waves is generated at low levels of the atmosphere and propagated upwards. The propagational effects of amplification, reflection, inter-modulation, and dissipation act to change the spectrum continuously with increasing height, and so produce different types of dominant modes at different heights. These changes, coupled with an observational selection in some cases, lead to the various characteristics revealed by the different observing techniques. The generation of abnormal waves locally in the ionosphere appears to be possible, and it seems able to account for unusual motions sometimes observed.
ON THE RATE OF CONVERGENCE OF THE SPHERICAL HARMONICS METHOD: (FOR THE PLANE CASE, ISOTROPIC SCATTERING)
Authors: Davison B.
Published: April 2011

The rate of convergence of the spherical harmonics method in neutron transport theory, for the plane case with isotropic scattering, is investigated, for an arbitrary number of layers of different materials, and both in the one-group and in the multi-group theory. The attention is centered upon the cases when there is no external supply of neutrons, so that one deals with an eigenvalue problem. The error in the eigenvalue due to the truncation of the spherical harmonics expansion is found to vary essentially as 0(1/N2), where N is the order of the highest harmonics retained. The proof of this result consists of two parts. Firstly it is shown that the use of the spherical harmonics method, under the conditions stated, is strictly equivalent to making a certain approximation in the kernel of the integral equation for the flux; and then the error due to this approximation is assessed.
TE SURFACE WAVES GUIDED BY A DIELECTRIC-COVERED METAL PLANE
Authors: Morris D. , Mungall A. G.
Published: April 2011

Investigations of the phase velocities of TE mode surface waves are described. The surface waves were excited over a sand-covered metal plane and the phase velocities of the first three TE modes determined as a function of the sand depth, at a frequency of about 9300 Mc/sec. A phase comparison system was used for the measurements. The simultaneous existence of two modes with different velocities, predicted theoretically for certain sand depths, was found experimentally.The variation of relative surface wave power carried above the dielectric layer with thickness of the layer is also discussed.
ON THE OPTICAL AND ELECTRICAL PROPERTIES OF SEMITRANSPARENT COPPER FILMS
Authors: Adhav R. S.
Published: April 2011

Simultaneous measurements were made of the optical constants n and k, reflectance R, transmittance T, and of the d-c. conductivity σ, of semitransparent copper films deposited onto quartz by evaporation in vacuo. All depositions were carried out at a pressure p ≈ 10−5 mm Hg and with a deposition rate D = 2 Å/sec. The optical constants were determined by an ellipsometer with a photo-multiplier tube attachment at the wavelengths 435 mμ, 546 mμ, and 630 mμ. The reflectance values were computed from the optical constants. The transmittance values were measured at these wavelengths by a unicam spectrophotometer. The d-c. conductivities were measured by a kohlrausch bridge. These measurements were carried out in the thickness range 60 Å to 455 Å. The disagreement of the results with the Garnett theory and the Fuchs theory is discussed and conclusions regarding the structure and the degree of porosity are drawn.
THE DECAY OF Pm149
Authors: Artna Agda , Law Margaret E.
Published: April 2011

The 52.8-hour activity of Pm149 has been investigated using a high resolution beta spectrometer, a lens type coincidence spectrometer, and a scintillation spectrometer in conjunction with a multichannel analyzer. The beta spectrum was found to consist of two groups with maximum energies of 1.072 ± 0.002 Mev and 0.786 ± 0.004 Mev, and intensities of 97.1 ± 0.4% and 2.9 ± 0.4% respectively. A gamma ray of energy 285.7 ± 0.3 kev was found to be in coincidence with the 0.786-Mev beta group. No other gamma rays with intensities greater than 0.1% were found. The K conversion coefficient for the 286-kev transition was measured to be 0.075 ± 0.008. This together with the values of 6.5 ± 0.7 and 4 ± 1 obtained for the K/L and L/M conversion ratios respectively indicate that this transition is M1 in character with less than 10% E2 admixture.
PROPAGATION OF ELECTROMAGNETIC WAVES ALONG A THIN PLASMA SHEET
Authors: Wait James R.
Published: April 2011

It is shown that a thin ionized sheet will support a trapped surface wave. The effect of a constant and uniform magnetic field is to modify the phase velocity and polarization of the surface wave. The essential features are illustrated by numerical results for selected values of the electron density, collision frequency, and gyro frequency. The effect of locating the plasma sheet near and parallel to a conducting plane is also considered. In this situation other modes of a waveguide type are possible in addition to the surface wave.
A MAGNETIC SUSCEPTIBILITY BALANCE AND THE TEMPERATURE DEPENDENCE OF THE MAGNETIC SUSCEPTIBILITY OF COPPER, SILVER, AND GOLD, 295°–975 °K
Authors: Garber M. , Henry W. G. , Hoeve H. G.
Published: April 2011

A magnetic susceptibility balance is described which has a reproducibility of better than ±0.15%. The temperature dependence of the magnetic susceptibility of copper, silver, and gold from 295° to 975 °K is reported.
THE IDENTIFICATION AND HALF LIVES OF FISSION-PRODUCT Rb92 AND Rb93
Authors: Fritze K. , Kennett T. J.
Published: April 2011

The existence of two new rubidium isotopes, Rb92 and Rb93, has been established and their half lives measured. The half lives of these short-lived fission products were determined using a technique of timed precipitations. The values obtained for Rb92 and Rb93 were 5.3 ± 0.5 sec and 5.6 ± 0.5 sec respectively. The half lives of the strontium and yttrium daughters were also determined. The strontium isotopes were studied by observing the decay rate of a characteristic γ-ray peak. For Sr92, the decay of the 1.37-Mev line gave a value of 2.71 ± 0.02 hr. A γ-ray peak at 590 kev, which was found to be associated with Sr93, decayed with a half life of 7.54 ± 0.06 min. The half lives of the yttrium daughters were determined by β counting. The values found for Y92 and Y93 were 3.53 ± 0.02 hr and 10.1 ± 0.1 hr respectively.
ELECTRON – HYDROGEN ATOM SCATTERING IN BORN APPROXIMATION
Authors: Wu Ta-You
Published: April 2011

The elastic (1s–1s) and the inelastic (1s–2s, 1s–2p) scattering cross sections in the Born approximation at energies of 1, 4, 9, 16 rydbergs have been calculated exactly from the closed formulas of the matrix elements for these transitions. Both the differential and the total cross sections are given here.
BACKSCATTERING FROM A CONDUCTING CYLINDER WITH A SURROUNDING SHELL
Authors: Plonus M. A.
Published: April 2011

Far-field backscattering from a perfectly conducting cylinder with a surrounding shell has been investigated. The spacing of the shell from the cylinder and thickness of the shell are arbitrary. The material in the shell is also arbitrary and is characterized by the propagation constant h. The incident plane wave is at right angles to the cylinder, and is either horizontally or perpendicularly polarized. When the shell is thin in units of wavelength a much simpler expression for the backscattered field coefficient is obtained. It was possible to express this coefficient in a form which resembles the coefficient from the conducting cylinder alone plus a perturbation term due to the shell. Another simplification resulted when the propagation constant h of the shell is much larger than the free-space propagation constant k.It was desirable to see what scattering properties a cylinder with a surrounding shell exhibits. The cylinder was chosen to be large with respect to wavelength and the shell spaced a resonant distance from the cylinder. The scattering cross section, for this particular combination of parameters was then given by a slowly converging series which proved too lengthy for hand-computation, and was then programmed for and computed by the IBM 704. The scattering cross section versus shell spacing is shown in graphical form.
THE CANADIAN STANDARD FREE-AIR CHAMBER FOR MEDIUM QUALITY X-RAYS
Authors: Henry W. H. , Garrett C.
Published: April 2011

A description is given of the Canadian standard free-air chamber for measurement of medium quality X-rays, including measurements of the contribution from radiation scattered from the air and from the diaphragm, and a method for the accurate alignment of the chamber and X-ray source.
THE "REACTOR" NEUTRON CAPTURE CROSS SECTION OF Y91
Authors: Milton Gwen M. , Grummitt W. E.
Published: April 2011

A high specific activity source of Y91, freed from natural uranium and rare earths, was irradiated in a high flux position in the NRX reactor. After further chemical purification, 3.6-hour Y92 was identified in the sample by measurement of the 3.6-Mev β-particle associated with its decay, using a scintillation spectrometer. Two such measurements have established the reactor neutron capture cross section of Y91 to be 1.4 ± 0.3 barns.
A POLARIZED NEUTRON BEAM PRODUCED BY BRAGG REFLECTION FROM CO–FE ALLOY
Authors: Clark M. A. , Robson J. M.
Published: April 2011

A single crystal of Co–Fe alloy is being used to produce a diffracted beam of neutrons with a flux of 2.6 × 106 n/sq. cm sec over an area of 1.5 in. by 1.5 in. This beam contains 92 ± 5% first-order neutrons (λ = 1.37 Å, E = 0.0436 ev), 3 ± 5% second- and higher-order neutrons, and 5% incoherently scattered neutrons. The first-order part of the beam has a polarization of 0.98 ±.01; the second-order part of the beam has a polarization of 0.36 ±.03 in the same direction as the first-order part, and the over-all beam has a polarization of 0.92 ±.05. The neutron spins can be reversed by the magnetic resonance technique with flipping efficiencies of 98% for the first order and 97% for the over-all beam.
THE ELECTRON ASYMMETRY IN THE BETA DECAY OF POLARIZED NEUTRONS
Authors: Clark M. A. , Robson J. M.
Published: April 2011

The coefficient of the angular correlation between the electron direction and the neutron spin direction in the beta decay of the neutron has been measured using a beam of polarized neutrons. The coefficient of this correlation is −0.09 ± 0.05. This implies that CA/CV, the ratio of the axial vector to vector coupling constants in neutron decay, is equal to −1.20 ± 0.12.
ELASTIC WAVES IN TRIGONAL CRYSTALS
Authors: Farnell G. W.
Published: April 2011

In non-isotropic single crystals the normals to the wavefronts of elastic waves are not colinear with the vectors representing either the energy flow or the particle displacement. Calculations have been carried out on the propagation characteristics of sound waves in two particular trigonal crystals, α-quartz and sapphire.The development of the eigenvalue equation for the velocity and the formulae for the components of the displacement and energy-flow vectors are summarized. The assumption that the wave has a plane wavefront normal to a given direction leads to three solutions, one representing a quasi-longitudinal wave and the other two representing quasi-transverse waves. The velocities of propagation, directions of displacement, and directions of energy flow for the three waves have been calculated for many orientations of the wave normal. Detailed results for propagation near one of the pure-mode axes are presented.
SCATTERING BY A GRATING. I
Authors: Millar R. F.
Published: April 2011

Consideration is given to scattering of plane waves by a transmission grating upon whose elements the wave function vanishes. By an application of Green's theorem, the problem is formulated in terms of integral equations for a finite, or infinite, number of elements. The equations are put in a form more suitable for the study of interaction phenomena by the subtraction of a certain series. The modified equations then correspond, more or less, to the excitation of each element of the grating by the incident field, and two plane waves propagated in opposite directions along the grating. A solution is here attempted only for the infinite grating of identical elements. Attention is confined to the region of "Rayleigh wavelengths", where interaction is important, and the variation in spectral intensity for a grating of elements of arbitrary form is discussed in a semiquantitative manner; the existence of anomalies is inferred. An explicit solution is obtained for small scatterers of elliptical cross section, and the behavior of the spectral intensity is considered in some detail.
SCATTERING BY A GRATING. II
Authors: Millar R. F.
Published: April 2011

The analysis of Part I is repeated for the second boundary value problem in which the normal derivative of the wave function vanishes on the elements of the grating; the existence of anomalies is again inferred. The behavior of the spectral intensity near an anomaly for a grating of small elliptic cylinders is considered and found to be much different from the case studied in Part I.The infinite reflection grating is discussed. Weak anomalies are predicted in the spectra for the case in which the wave function vanishes on the grating; strong (Wood) anomalies are found in the spectra for the second problem.The finite transmission grating is treated very approximately. Anomalous behavior, dependent now on the number of elements, is inferred.
THE EFFECT OF QUENCHING AND NEUTRON IRRADIATION ON INTERNAL FRICTION OF ALUMINUM–5% MAGNESIUM ALLOY
Authors: Nilson W. G.
Published: April 2011

Low frequency internal friction data were obtained on the alloy aluminium–5% magnesium to determine the effects of quenching and neutron irradiation on solute movement. A damping peak near 150 °C, attributed to stress-induced reorientation of solute atoms, was found to be shifted to lower temperatures by these treatments. This behavior corresponds to a reduction in relaxation time for the damping process, and is compatible with the idea that the solute atoms act as traps for vacancies.
MAXWELL'S EQUATIONS AND MATRIX ELEMENTS IN QUANTUM ELECTRODYNAMICS
Authors: Venables H. A.
Published: April 2011

Matrix elements of second-order processes in quantum electrodynamics are obtainable directly from the use of Maxwell's and Dirac's equations.
AN ELECTRON SPIN RESONANCE STUDY OF MANGANESE IMPURITY IN BRUCITE
Authors: Pieczonka W. A. , Petch H. E. , McLay A. B.
Published: April 2011

A single crystal of brucite, Mg(OH)2, containing manganese impurity to the extent of 100 parts per million, has been studied by means of the electron spin resonance (esr) technique. The study was made at room and liquid air temperatures. The observed absorption spectrum has been successfully interpreted in terms of parameters found in the appropriate spin-Hamiltonian. The measured values of these parameters at room temperature were found to be:[Formula: see text]
PREDISSOCIATION IN THE HNO MOLECULE
Authors: Clement M. J. Y. , Ramsay D. A.
Published: April 2011

Twelve bands of HNO and 18 bands of DNO in the region 6,000 to 10,000 Å have been photographed in emission during the reactions of hydrogen and deuterium atoms with nitric oxide. Two of the HNO bands and 3 of the DNO bands show a sharp breaking-off in the K-rotational structure, due to predissociation of the molecule in the excited state. Upper limits for the dissociation energies of HNO and DNO are 48.6 kcal/mole and 49.1 kcal/mole respectively.
THE ABSORPTION SPECTRUM AND DISSOCIATION ENERGY OF SH
Authors: Johns J. W. C. , Ramsay D. A.
Published: April 2011

The (2,0) bands of the A2Σ+−X2Π system of SH and SD have been photographed for the first time. More accurate values for the vibrational constants of the A2Σ+ state have been obtained. The dissociation energy of SH in the excited state is [Formula: see text] from which it is possible to deduce that the ground state dissociation energy [Formula: see text] (SH) is 28,480 ± 1000 cm−1 (81.4 ± 2.9 kcal/mole, 3.53 ± 0.12 ev).
THE EXTENSION OF HOUSTON'S METHOD WITH APPLICATION TO DEBYE Θ0
Authors: Betts D. D.
Published: April 2011

Houston's method of integration over the unit sphere of functions of cubic symmetry is extended by developing integration formulas using 9 and 15 values of the integrand. The 3-, 6-, 9-, and 15-term Houston formulas are used to calculate Debye Θ0 values for a number of cubic crystals. The convergence of the results is excellent except for the most anisotropic crystals.
ASYMMETRY IN THE RECOVERY FROM A VERY DEEP FORBUSH-TYPE DECREASE IN COSMIC-RAY INTENSITY
Authors: Rose D. C. , Lapointe S. M.
Published: April 2011

The intensity–time curves for cosmic rays recorded at some 30 stations distributed all over the world are examined for structure in the recovery period from the third in a series of three closely spaced Forbush-type decreases which occurred in the middle of July 1959. It is shown that the structure of intensity peaks is regular and that these occur at each station at the same effective local time. It is found that this is consistent with the hypothesis that recovery from a very deep Forbush-type decrease is first apparent in directions making 15° and 165° with the sun–earth line respectively. The analyses suggest further, that during recovery from this deep Forbush decrease temporary openings appeared in the intensity depressing mechanism which allowed intensity increases in limited directions.
AN ITERATIVE METHOD FOR NEUTRON TRANSPORT PROBLEMS WITH SPHERICAL SYMMETRY
Authors: Conkie W. R.
Published: April 2011

An iterative method developed previously for transport problems with plane symmetry has been extended to problems with spherical symmetry. Particular application has been made to the problem of the neutron distribution for a black sphere embedded in a purely scattering medium with sources at infinity. The results compare favorably with those of other workers for this problem.
THE STATISTICAL BEHAVIOR OF INSTABILITIES IN DISPLACEMENT PROCESSES IN POROUS MEDIA
Authors: Scheidegger Adrian E. , Johnson Edward F.
Published: April 2011

The problem of growth of instabilities (fingers) in displacement processes in porous media is analyzed from a statistical viewpoint. The relative area occupied by fingers is represented as a "saturation", and the equations of motion for this "saturation" are derived. It is shown that these equations are analogous to the Buckley–Leverett equations of immiscible displacement, with a fictitious "relative permeability" being introduced. The latter can be calculated and thus the statistical equations of motion of a fingered-out front can be written down explicitly. These equations of motion can then be solved by the well-known method of characteristics. It is shown that the statistical theory does not lead to any stabilization of the fingers.
EQUIVALENCE BETWEEN CONTINUOUS AND DISCRETE RADIATING ARRAYS
Authors: Ksienski A.
Published: April 2011

The radiation patterns produced by continuous excitation distributions and discrete arrays are compared and the conditions are derived under which one type of source may be substituted for the other with negligible errors. It is shown that the aperture lengths in both cases should be the same but the element spacing is dependent on the type of pattern desired. Examples are computed to demonstrate these relations for both directive patterns and shaped beams.
THE ROLE OF REPULSIVE CORES IN THE PHOTONUCLEAR EFFECT
Authors: Clark John W.
Published: April 2011

The dipole sum rule is used to investigate the effect of nuclear forces on the integrated photonuclear cross section σint of a large nucleus, for a Serber potential containing a hard core. A Jastrow wave function is assumed to describe the nuclear ground state, and the first term in the cluster expansion of the resultant expression for σint evaluated under two different sets of assumptions for the potential and correlation function, corresponding to two different studies of the nuclear matter problem. The presence of a repulsive core in the potential is found to enhance considerably the calculated σint, compared with the result for a potential without a core which fits the same (low-energy) two-nucleon data.
INTERFÉROMÈTRE MICRO-ONDE À FOND COHÉRENT
Authors: Boivin A. , Tremblay R.
Published: April 2011

not available
DÉPHASEUR MICRO-ONDE À PRISMES DIÉLECTRIQUES
Authors: Tremblay R.
Published: April 2011

not available
THE RAMAN SPECTRUM OF METHANE-d4
Authors: Olafson R. A. , Thomas M. A. , Welsh H. L.
Published: April 2011

The Raman spectrum of CD4 at 1 atm pressure was photographed with a spectral resolution of ~0.4 cm−1, and rotational analyses of the ν2 and ν3 bands were carried out. The B0 values obtained from the ν2 and ν3 bands are 2.6330 ± 0.0007 and 2.6328 ± 0.0007 cm−1, respectively; the value of r0 determined from the former is 1.09181 ± 0.00029 Å. The rotational levels of the ν = 1 state of ν2 are split with effective B1 values equal to 2.6894, 2.7351, and 2.7434 cm−1. Thirteen of the fifteen branches of the ν3 band were observed; these also show multiple B1 values. The value obtained for ζ3 is 0.1648. Structure was observed but not analyzed in the ν1, 2ν4, and ν2 + ν4 bands. On the basis of the Raman data the structures of the ν2 and ν3 infrared bands are discussed.
ANALYSIS OF A TYPE OF ROUGH-TRAIL METEOR ECHO
Authors: McIntosh B. A.
Published: April 2011

For a particular type of meteor echo, the variation of echo duration with atmospheric height is examined. Theory based on an initially rough meteor trail is substantiated by showing that atmospheric scale heights calculated from measurements on these echoes are in agreement with generally accepted values.
MAGNETORESISTANCE AND HALL EFFECT IN ORIENTED SINGLE CRYSTAL SAMPLES OF n-TYPE INDIUM ANTIMONIDE
Authors: Champness C. H.
Published: April 2011

Measurements have been made on the angular dependence of the magneto-resistance effect and the Hall effect on oriented n-type indium antimonide samples. The measurements were taken at room temperature and liquid air temperature using a magnetic field strength of about 5000 gauss. Besides evidence of inhomogeneity, the results show directional dependence of the longitudinal magnetoresistance. The largest value was found in the [Formula: see text] direction. This can be explained if, in addition to electrons at the central minimum, there is some filling of the [Formula: see text] minima in k space.
THE 1600 Å BAND SYSTEM OF AMMONIA
Authors: Douglas A. E. , Hollas J. M.
Published: April 2011

The progression of ammonia bands which extends from 1689 to 1400 Å has been photographed in absorption at high resolution. Six bands have been analyzed and found to be of the perpendicular type. The analysis shows that the molecule is planar in the excited state and that vibrational levels observed in the progression are those of the out-of-plane vibration. The excited electronic state is of the E′′ type. In addition to the normal Coriolis interaction of the degenerate levels, a second effect has been observed which behaves like the Coriolis interaction recently described as 'giant l-type doubling' by Garing, Nielsen, and Rao. No clear evidence has been found for any distortion of the degenerate state from D3h symmetry.
RADIO-STAR SCINTILLATIONS AND THE AURORAL ZONE
Authors: Forsyth P. A. , Paulson K. V.
Published: April 2011

A continuous series of observations of scintillations of the radio star, Cassiopeia A, carried out at Saskatoon at a frequency near 53 Mc/s over a period of nearly 4 years has been analyzed. The altitude-angle dependence of the scintillations was very strong in 1955 but weak in 1958. This behavior suggests that the scintillations are not produced in a uniform layer of the atmosphere. It seems more likely that the scintillations arise most strongly in regions of the atmosphere closely associated with the auroral zone and that these regions migrate southward during years of intense sunspot activity.
REPRESENTATIONS OF THE UNITARY GROUP AND WAVE FUNCTIONS
Authors: Venables H. A.
Published: April 2011

A number of wave functions besides the spherical harmonics are obtainable from the irreducible representations of the two-dimensional unitary group.
MICROWAVE NOISE IN ACCELERATED ELECTRON STREAMS
Authors: McFarlane R. A.
Published: April 2011

Measurements have been made of the noise current fluctuations on the electron beam from a space-charge limited diode electron gun, at 1,400 Mc/s, 4,250 Mc/s, and 9,520 Mc/s. Theories which do not consider the finite beam diameter and the multivelocity nature of the stream in the region of the potential minimum are in poor agreement with experiment. The measurements here reported and those of other workers are compared with the results of theoretical calculations in which these two effects are considered. Significant improvement in agreement with experiment is realized.
Zn:Tl PHASE DIAGRAM AT VERY LOW THALLIUM CONCENTRATIONS
Authors: McLaren E. H. , Weinberg F.
Published: April 2011

The Zn:Tl liquidus has been accurately determined from pure Zn (419.505 °C) to the monotectic transition temperature (416.926 °C at 0.42 at.% Tl) using precision resistance thermometry. The upper solidus was determined approximately from measurements of the distribution coefficient (~0.01) and the solid solubility limit (~0.004 at.% Tl) of thallium in zinc. A value 1.53 ± 0.1 kcal/mole for the latent heat of fusion of pure zinc was calculated from the freezing point depressions.
THE ELECTRICAL CONDUCTIVITY OF GELATIN FILM HUMIDIFIED WITH HEAVY WATER VAPOR
Authors: Niven C. D.
Published: April 2011

When protons were replaced by deuterium nuclei in gelatin films, by exposure of dry films in 75% relative humidities, the resistance increased very markedly.
HALF LIFE, Qβ VALUE, AND γ-RAY SPECTRUM OF La143
Authors: Fritze K. , Kennett T. J. , Prestwich W. V.
Published: April 2011

The decay of La143 has been investigated. A half life of 14.0 ± 0.1 min and a Qβ value of 3.3 ± 0.1 Mev were found. The γ radiation is weak and the spectrum is rather complex.
THE EFFECTIVE DIRECTIONAL SENSITIVITY OF COSMIC-RAY NEUTRON MONITORS
Authors: Lapointe S. M. , Rose D. C.
Published: April 2011

The direction of maximum sensitivity of a neutron monitor is calculated numerically for a set of points on the same geomagnetic meridian but extending in latitude from the equator to the pole. This leads to two master curves, one for the longitude, the other for the latitude of this direction. From these curves this direction is obtained in geographic co-ordinates for some 20 cosmic-ray stations. The method of calculation is described taking into account atmospheric absorption and the energy spectrum of the incident particles. The aperture of the sensitive cone, or source width, is also calculated. Finally the accuracy of the results is discussed and the application of the concept of effective direction is described.
MODELS OF AURORAL IONIZATION: PART I. AURORAL IONIZATION MODELS AND THEIR RADIO-REFLECTION CHARACTERISTICS
Authors: Moorcroft D. R.
Published: April 2011

Although radio observations of aurora contain information about the nature of the reflecting ionization, the use of dissimilar models of auroral ionization has led different workers to widely differing conclusions. In this paper several general models of auroral ionization are developed. By considering the ionization as an assembly of individual scatterers, it has been possible to include a unified treatment of both weak scattering and critical reflection. This treatment should provide a basis for resolving some of the difficulties in the interpretation of auroral radio observations. In a second paper the available experimental evidence is examined in the light of this theoretical treatment.