bluuebunny/crossref_metadata_2025 huggingface dataset:
CRYSTAL ORIENTATION IN ICE SHEETS
Authors: Perey F. G. J. , Pounder E. R.
Published: April 2011

Crystal size and orientation in ice sheets frozen under one-dimensional cooling from melts of pure water or melts containing traces of organic additives were studied using a polariscope with a universal stage. The surface layer is found to consist of crystals with nearly vertical optic axes. Horizontal sections cut at various depths show a gradual change of the mean orientation of the optic axes towards the horizontal. The change to horizontal inclinations is almost completed at depths of 4 or 5 cm. under the freezing conditions used, and occurs more rapidly with the melts containing additives. With additives the ice sheet shows another feature also, a transition layer about 0.5 cm. below the surface. In this layer the crystals are much smaller than in the surface layer above them and the number of crystals extending through this layer is small.An explanation of the observations is offered, in terms of preferred growth of an ice crystal in planes perpendicular to the optic axis. This provides a mechanism permitting more rapid growth of crystals with inclined axes.
THE THERMAL-NEUTRON FISSION CROSS SECTION OF Pu240
Authors: Bigham C. B.
Published: April 2011

A measurement of the thermal-neutron fission cross section of Pu240 is described. The value obtained, −0.8 ± 0.7 barn, is compared with other measurements.
A THEORETICAL RATE–AMPLITUDE RELATION IN METEORIC FORWARD-SCATTERING
Authors: Hines C. O.
Published: April 2011

The theory of the forward-scattering of radio waves by ionized meteor trails is applied to the development of a rate-amplitude relation. This relation expresses the anticipated occurrence rate of scattered signals which exceed a chosen amplitude level, as a function of that level. It is compared with preliminary observational data, and found to be in good agreement both qualitatively and quantitatively. Closest agreement is obtained only with an appropriate choice of two scaling factors. These provide an abstract of the observations in a form which is convenient for further study and interpretation.
A NEW BAND SYSTEM OF THE P2 MOLECULE ANALOGOUS TO THE LYMAN–BIRGE–HOPFIELD BANDS OF N2
Authors: Douglas A. E. , Rao K. Suryanarayana
Published: April 2011

Five bands of a new band system of P2 have been photographed at high dispersion and analyzed. The upper state of the system is a 1П0 state and lies lower than any previously known excited singlet state. The lower state of the new system is the ground state of P2 and the analysis of the new bands has given improved constants for this state. The new system appears to be the analogue of the Lyman–Birge–Hopfield bands of N2. The electron configuration of the low excited states of P2 and of related molecules is discussed.
THE FREEZING POINTS OF HIGH PURITY METALS AS PRECISION TEMPERATURE STANDARDS: III. THERMAL ANALYSES ON EIGHT GRADES OF ZINC WITH PURITIES GREATER THAN 99.99 + %
Authors: McLaren E. H.
Published: April 2011

Extensive thermal analyses have been carried out on eight grades of high purity zinc with the suppliers' analyzed impurity contents in the range < 0.5 to <70 p.p.m. The liquidus points have been intercompared with a precision of about 0.0002 °C. and the alloy melting ranges have been examined following different rates of freezing. A melting range parameter may provide a more sensitive index of the purity than the liquidus temperature since the shape of the melting curve is strongly influenced by segregation of impurities due to coring on freezing. Two grades of Russian high purity zinc have liquidus points and melting ranges so close to those of New Jersey S.P. zinc that it is difficult to discriminate among them using precision resistance thermometry. This shows that a reported discrepancy of about 0.1 °C. in the freezing points of zinc between the Russian and Canadian laboratories is not due to different impurity contents of the zincs that were used.
ON THE FRICTION OF INFLATED RUBBER TIRES ON ICE
Authors: Niven C. D.
Published: April 2011

The friction on ice of some small inflated rubber tires was measured on a turntable in a cold room. When rolling-friction force was plotted against load, the relation was either linear or slightly curved away from the load axis; such curvature implies that Thirion's Law does not hold for rolling friction. On the other hand when sliding-friction force was plotted against load the curvature was toward the load axis as would be expected if Thirion's Law applied. The coefficient of friction can go as low as 0.01 or even lower for a hard-pumped tire when the temperature is near 0 °C, but at −1 °C. rolling friction on dry ice is quite appreciable. The results refer only to measurements at very slow speed.
THE RANDOM-WALK MODEL WITH AUTOCORRELATION OF FLOW THROUGH POROUS MEDIA
Authors: Scheidegger A. E.
Published: April 2011

In pursuit of the idea of applying statistical mechanics to the theory of flow through porous media, this paper reports an investigation of the implications of a random-walk model as opposed to random residence-time models. Although the random-walk model is physically not as satisfactory as other statistical models, it has the advantage of enabling one to introduce and to investigate easily the effect of autocorrelation between subsequent time steps. It is shown that, if autocorrelation exists, the mixing process in porous media is governed by a telegraph equation rather than by a diffusivity equation. Expressions for the constants occurring in the telegraph equation are deduced in terms of other dynamical variables.
ELECTRON BEAM FLUORESCENCE PROBE FOR MEASURING THE LOCAL GAS DENSITY IN A WIDE FIELD OF OBSERVATION
Authors: Schumacher B. W. , Gadamer E. O.
Published: April 2011

An electron beam was fired across the field of observation of the UTIA low-density wind tunnel. Along its path gaseous fluorescence was excited and visible light emitted. The total light output per unit length of the electron beam can be assumed to be proportional to the density of the gas if suitable spectral lines are selected. A three-dimensional scan of the field would give the local density for each spot. Visual, photographic, and photometric observation is possible. Some photographs are presented along with approximate data for the light output in air. The spatial resolution of the fluorescence probe is also discussed.
KINETICS OF ALLOY SOLIDIFICATION
Authors: Jackson K. A.
Published: April 2011

Alloy systems are discussed in terms of the theory of interface kinetics which was developed in a previous paper (Jackson and Chalmers 1956). The non-equilibrium equations which are developed reduce to the thermodynamic expressions if the system is in equilibrium. Several types of phase diagrams are discussed. It is shown that a phase diagram gives a reasonably good estimate of the concentrations at an interface if the system is not in equilibrium.
THÉORIE DE LA DIFFUSION AU COURS DU DÉVELOPPEMENT DES COUCHES IONOGRAPHIQUES ÉPAISSES
Authors: Demers Pierre
Published: April 2011

not available
ON THE DISPLACEMENT OF AN ION BEAM IMAGE BY MAGNETIC FRINGING FIELDS
Authors: Kerwin Larkin
Published: April 2011

Some of the methods proposed for calculating the effect of the magnetic fringing field on the image position of an ion beam are reviewed, and applied to the case of a particular instrument. The differences between the calculated corrections and the observed image suggest an improved method of calculating the image position. Applied to the case under consideration, this method gives essentially the correct image position.
THE ELECTRIC STRENGTH AND MOLECULAR STRUCTURE OF HYDROCARBON GASES
Authors: Heylen A. E. D. , Lewis T. J.
Published: April 2011

Precise measurements of the sparking potentials of a number of hydrocarbon gases over a wide range of pressure and electrode spacing are reported. The range has been extended beyond that reported earlier to include the n-paraffins up to n-octane and the olefins up to hexene-1. The effect of the triple bond in acetylene and conjugation in butadiene as well as the effects of cyclization are included. Careful experimental control involving the observation of prebreakdown pulses is an important feature of the measurements, and all the gases tested were of the highest purity.A theoretical argument is given, relating the sparking potentials Vs to the molecular structure of the gases. This assumes a Townsend criterion for breakdown and a particular expression for the Townsend α coefficient. It is then possible to obtain information concerning the relative electron-scattering cross-sections of these hydrocarbons, which are related not to the molecular bonds as has been suggested earlier, but to individual atomic groups. With such a model, CH3 and CH2 groups and groups involving double or triple bonds have characteristic cross-sections. The theory then becomes closely allied to that for the ultraviolet spectra of these hydrocarbons. It appears that the present system of description is a more natural one than that involving bond cross-sections.It is believed that dissociation occurs readily in many hydrocarbons and that photon action is small. This produces a value of γ (the second Townsend coefficient) which is very small (~10−8) in comparison with the value (~10−4) in more common gases. Such a low value can account for the considerable pulse activity observed in these hydrocarbon gases before breakdown occurs. Few pulses were observed in cyclopentane and cyclohexane, which do not dissociate readily, and it appears that a more usual value of γ = 10−4 occurs in these particular gases.
THE THEORY OF COLLISION-INDUCED ABSORPTION IN HYDROGEN AND DEUTERIUM
Authors: Britton F. R. , Crawford M. F.
Published: April 2011

Collision-induced absorptions in the 1–0 vibrational band of hydrogen and of deuterium are calculated by considering interactions during binary collisions. The induced dipole moment, μ, of an interacting molecule-pair is derived by combining a moment, μa, resulting from overlap forces, with a moment, μq, due to the interactions of permanent molecular quadrupole moments. μa consists of two additive parts, an indirect part calculated by van Kranendonk and Bird (1951) and a direct part calculated in this paper. μq is calculated in two different ways: (a) theoretically and (b) semiempirically. Absorption coefficients are evaluated for temperatures 296 ° K. and 80 ° K. For H2 at 296 ° K. the total integrated coefficient obtained by using procedure (a) is 8.6% smaller and by using (b) is 8.2% larger than the experimental value. The experimental ratio of the coefficients of the Q and S branches is in much better agreement with (b) than (a). For T = 80 °K. the experimental value of the total integrated coefficient is only 61% of that calculated by (b). The good agreement between calculated and experimental values of absorption coefficients at room temperature suggests that at low temperatures the classical distribution function used in this paper must be replaced by the quantal pair distribution function. Experimental data for D2 are not available.
A COSMIC RAY INCREASE RELATED TO SOLAR ACTIVITY
Authors: Katzman J.
Published: April 2011

An increase in the intensity of cosmic ray particles of minimum momentum at Ottawa, Canada, of 4.5 × 109 ev/c was observed with telescopes of solid angles 11.5 × 10−4 and 26.0 × 10−4 steradians with increase of solar activity. A large increase in cosmic ray activity for the period September 1956 to February 1957 was observed to accompany a large and sustained increase in solar activity as determined by means of the critical frequency of the F-2 layer.
MEASURED SELF-IMPEDANCE OF A DIPOLE ANTENNA NEAR A CONDUCTING CYLINDER OF ELLIPTICAL CROSS SECTION
Authors: Wong J. Y.
Published: April 2011

This paper presents the results of an experimental investigation of the impedance of an axial dipole antenna located near a conducting cylinder of elliptical cross section. Measurements were carried out for various spacings of the antenna from the cylinder along the major and minor axes, and for four different values of cylinder ellipticity.For a cylinder having a maximum dimension of 0.76 wave length it is found that the impedance (resistive and reactive components) is an oscillating function of the antenna-to-cylinder spacing, having a period of approximately one-half wave length. For spacings greater than one wave length, the impedance is within 5% of the free-space dipole impedance.
THE CROSS SECTION FOR THE REACTION Cs135(n, γ)Cs136
Authors: Baerg A. P. , Brown F. , Lounsbury M.
Published: April 2011

The effective cross section for the reaction Cs135 (n, γ) Cs136 with reactor neutrons is 10.4 ± 0.5 barns. The measured reaction rate under cadmium yields a value of 61.7 ± 2.3 barns for the resonance integral of Cs135. The thermal cross section is 8.7 ± 0.5 barns as obtained by combining the reaction rates for uncovered and cadmium-covered samples.
LOW TEMPERATURE RESISTIVITY OF THE TRANSITION ELEMENTS: RUTHENIUM AND OSMIUM
Authors: White G. K. , Woods S. B.
Published: April 2011

Experimental values are reported for the electrical resistivity of ruthenium and osmium from 2 to 300 °K and for the thermal resistivity from 2 to 140° K. The samples were produced by arc-melting pressed pellets of metallic powder in an inert gas atmosphere. Two osmium samples and one ruthenium sample showed a satisfactorily low residual electrical resistance. By grinding these rods to a regular shape, absolute values of resistivity were obtained and the impurity and thermal components of resistivity derived; at room temperature (295 °K) we deduce that for ideally pure Os, [Formula: see text] and for ideally pure ruthenium [Formula: see text]. The temperature dependence of the resistivity was markedly different for another ruthenium sample but it seems likely that this was not representative of pure h.c.p. ruthenium.
DIFFUSION IN MULTICOMPONENT METALLIC SYSTEMS: I. PHENOMENOLOGICAL THEORY FOR SUBSTITUTIONAL SOLID SOLUTION ALLOYS
Authors: Kirkaldy J. S.
Published: April 2011

Onsager's generalization of Fick's law for diffusion in multicomponent systems is examined with a view to determining the conditions imposed on the diffusion coefficients by the second law of thermodynamics and by "microscopic reversibility." The generalized differential equations with constant coefficients, obtained by combining Fick's law and the continuity equations, are solved for the boundary conditions corresponding to the semi-infinite diffusion couple.
DIFFUSION IN MULTICOMPONENT METALLIC SYSTEMS: II. SOLUTIONS FOR TWO-PHASE SYSTEMS WITH APPLICATIONS TO TRANSFORMATIONS IN STEEL
Authors: Kirkaldy J. S.
Published: April 2011

The generalized differential diffusion equation for multicomponent systems with constant coefficients is solved for an advancing linear, cylindrical, or spherical two-phase interface. Representative numerical calculations for ternary alloys based on the iron, carbon system demonstrate how inhibition of the transformation austenite to ferrite + carbide can occur through the requirement of maintaining (extrapolated) equilibrium at the interface and through the interaction of carbon atoms with the off-diagonal gradients in the diffusion matrix. It is proposed that these interactions are the primary cause of hardenability effects in steel.
DIFFUSION IN MULTICOMPONENT METALLIC SYSTEMS: III. THE MOTION OF PLANAR PHASE INTERFACES
Authors: Kirkaldy J. S.
Published: April 2011

Onsager's phenomenological scheme is adapted to unidimensional diffusion in a multiphase, multicomponent system with constant diffusion coefficients. Subject to initial conditions corresponding to the semi-infinite diffusion couple, an exact solution of the multicomponent equations is obtained from which the planar interface motions can be calculated. The similar but unrelated motion of markers that occurs in the diffusion zone of some single-phase couples is discussed and Darken's phenomenological description for binary alloys is extended to multicomponent systems.
ALPHA DECAY OF SPHEROIDAL NUCLEI
Authors: Pennington E. M. , Preston M. A.
Published: April 2011

A system of coupled differential equations relates the amplitudes of alpha particle waves emitted from a spheroidal nucleus described by the Bohr–Mottelson model. These equations in spheroidal coordinates have been solved for five even–even nuclides with the aid of the electronic computer FERUT. There are four possible cases for each nuclide which are consistent with the boundary conditions. The solutions of the equations are used to calculate the probability density of alpha particles on the nuclear surface for each case. For Case I the peak in the distribution function shifts from the nuclear symmetry axis to the equator with increasing mass number. The probability density for Case II is always peaked between the symmetry axis and the equator, while for Cases III and IV it is always peaked strongly at the equator. The change in the distribution function with increasing distance from the nucleus is considered for a typical case. Barrier penetration factors are calculated and found to differ from those for spherical nuclei by factors of the order of 2 or 3. Comparison with the calculations of an approximation method of Fröman is made for one nuclide.
THE NUCLEAR ABSORPTION OF X-RAYS BY OXYGEN
Authors: Siddiq A. K. M. , Haslam R. N. H.
Published: April 2011

The total X-ray attenuation ratio in water was measured as a function of energy in the region 15–25 Mev, with a view to studying the nuclear absorption process in oxygen. The known energy response characteristics of several "activity detectors" (Zn64(γ, n)Zn63, C12(γ, n)C11, S32(γ, d)P30, O16(γ, n)O15) to bremsstrahlung were employed in these measurements.The experimental values of the attenuation ratios were compared to the predicted values calculated on the basis of various assumptions concerning the nuclear absorption process.The best description of the nuclear absorption process in oxygen appears to be continuous absorption on which relatively small absorption peaks are superimposed.
THE ELECTRICAL CONDUCTIVITY OF MANGANESE ARSENIDE AND ANTIMONIDE
Authors: Fischer Gaston , Pearson W. B.
Published: April 2011

New measurements of the electrical resistivity of MnAs and MnSb are reported as part of a program of relating the electronic and crystal structure of compounds to their electrical properties. Modern experimental methods have been used in an attempt to obtain better samples and to avoid the formation of cracks which greatly influence the measured resistivity. The electrical resistivity of MnAs in the paramagnetic range where it is fairly independent of temperature is about 5 × 10−4 ohm cm. In the ferromagnetic range it is about 2 × 10−4 ohm cm at 0 °C with a temperature coefficient of 5 × 10−3 per °C.
FIELD-INDUCED ABSORPTION IN HYDROGEN
Authors: Crawford M. F. , MacDonald R. E.
Published: April 2011

This paper reports an investigation of the fundamental rotation–vibration absorption induced in hydrogen by an electric field. The integrated absorption coefficients of the first four components of the Q branch have been measured for a range of field strengths at densities of 83.9 and 44.6 Amagat. The integrated absorption coefficient of the S(1) line has been determined at the higher density for one high field strength. The relative intensities of the Q components are in good agreement with the predicted ratios. Accurate experimental values of the matrix element of the mean value of the polarizability, (α)01, and the matrix element of its anisotropy, (γ)01 have been obtained. They are: (α)01 = 0.968 × 10−25 cm3, and (γ)01 = 0.72 × 10−25 cm3 at 83.9 Amagat, and are only slightly dependent on density. The frequencies of the lines have been measured. Only Q(1) and S(1) show a measurable shift with density. The optical collision diameter has been determined and is very small, 0.26 Å.
THE FORWARD-SCATTERED RADIO SIGNAL FROM AN OVERDENSE METEOR TRAIL
Authors: Forsyth P. A.
Published: April 2011

A recently presented expression for the forward-scattered signal from an over-dense meteor trail is tested by applying it to the signals scattered from a single meteor trail. The particular trail was selected carefully in order to permit the derivation of each of its parameters in several different ways. The internal consistency of the derived information is taken as a measure of the validity of the theoretical expression. In particular, the electron line density at each of two reflection points is derived by three different methods, of which two depend upon the new expression, and the other depends only upon well-established theory. The resulting agreement is within the experimental error and suggests that the new expression is an adequate working relation for use in experimental investigations.
LOW TEMPERATURE BEHAVIOR OF DEBYE CHARACTERISTIC TEMPERATURES
Authors: Schiff H. , Horton G. K.
Published: April 2011

The low temperature behavior of the characteristic Debye temperature is investigated using the six- and nine-direction Houston approximation and by way of illustration, the lattice dynamics of Born and Begbie (nearest neighbors only). We study the values of θ0 and B2 for Cu, Au, Ag, Al, and Pb in the formula θT = θ0 θ. The existence in Pb of a shallow maximum before the usual minimum, found earlier by Bhatia and Horton, is confirmed. The method is quite general and may be used for non-metals and with other theoretical models.
CONDENSATION COEFFICIENTS OF SILVER, GOLD, AND COPPER IN VACUUM DEPOSITION
Authors: Chandra S. , Scott G. D.
Published: April 2011

A beam of atoms striking a substrate will in general not condense completely, but some of the incident atoms will re-evaporate. The condensation coefficient– denfined as the ratio of the number of atoms condensing to the total number incident on the substrate–has been determined for silver at substrate temperatures from −30 °C to 170 °C, and for gold and copper at temperatures from 25 °C to 165 °C. For silver at room temperature the condensation coefficient is found to be 0.936, which indicates 6.4% of the incident atoms are re-evaporated or diffusely reflected. By a simple graphical analysis of the results it is shown that the temperature below which complete condensation occurs is 200 °K for silver, 230 °K for gold, and 180 °K for copper.
SOME GEOPHYSICAL APPLICATIONS OF THE ELASTICITY THEORY OF DISLOCATIONS
Authors: Steketee J. A.
Published: April 2011

In this paper some aspects of the elasticity theory of dislocations (E.T.D.) which may be of geophysical significance are discussed. The central position of A- and B-nuclei of strain in this theory is emphasized. Applications to cracks and seismological models are indicated. Some limitations of the E.T.D. for applications to geophysics appear in the discussion of strain energy. Finally the displacement field at the surface of a semi-infinite elastic medium which contains a particular B-nucleus at depth c is discussed. Although the considerations in this paper are in several respects incomplete and of a preliminary character it is expected that the reader may recognize the analogy of the E.T.D. with potential theory and will appreciate the power of the theory to unify several isolated problems on cracks and seismological models and to suggest further applications which are of geophysical interest.
THE THEORY OF FORBIDDEN β-DECAY
Authors: Lee-Whiting G. E.
Published: April 2011

The angular distributions of electrons and of neutrinos and the polarization of the electrons emitted by an oriented source in β-decay of arbitrary forbiddenness are calculated in terms of various angular-momentum coupling constants and of certain generalizations of the well-known combinations of electron radial wave-functions, Lv, Mv, Nv,.... The interaction Hamiltonian used encompasses all five invariants; neither parity conservation nor time-reversal invariance is assumed. A particularly simple procedure for calculating the longitudinal polarization of electrons emitted by an oriented source is pointed out. The polarization is equal to ± v/c, to good approximation, if the two-component neutrino theory holds. Explicit results for various allowed and first-forbidden effects are quoted.
SOME OBSERVATIONS ON THE DEPENDENCE OF STRAIN ON STRESS FOR ICE
Authors: Gold L. W.
Published: April 2011

Observations were made on the longitudinal and transverse strain of rectangular ice samples stressed at the rate of 2 kg/cm2/sec to a maximum stress of 10 kg/cm2. The duration of the stress was kept less than 10 seconds. Under these conditions the ice behaved elastically. The observations indicated that two deformation processes contributed to the measured strain. It is concluded that the two sources of strain are deformation of the grains and slip at the grain boundaries.
ACTIVATION CROSS SECTIONS FOR C12(p, pn)C11, O16(p, α)N13, and F19(p, pn)F18
Authors: Whitehead A. B. , Foster J. S.
Published: April 2011

The activation cross sections for proton-induced nuclear reactions were studied in the region from threshold over a range of about 10 Mev proton energy. The scattering and 180°-focussing technique for proton irradiation was employed to realize improved energy resolution.The reaction O16(p, α)N13 exhibited three large peaks at proton energies of 8.6 Mev, 11.3 Mev, and 14.6 Mev in the laboratory system. The maximum cross sections were 46 mb, 55 mb, and 45 mb respectively.Though not so pronounced as in the oxygen case, minor peaks in the cross section for C12(p, pn)C11 + C12(p, d)C11 modulated the previously smooth curve. These occurred at energies of 19.8 Mev, 20.9 Mev, and 22.2 Mev. The known excitation function for this reaction was extended from 32 Mev to 42 Mev and proved to be flat, thereby clarifying the normalization between the higher- and lower-energy regions.The irradiation of F19 with protons to produce F18 yielded a cross section which was a smooth function of energy, and thus differed in shape from the corresponding carbon curve.
THE NUCLEAR SPIN RESONANCE SPECTRUM OF Al27 IN SPODUMENE
Authors: Robinson L. B.
Published: April 2011

An experimental study has been made of the nuclear spin resonance spectrum of Al27 in a single crystal of spodumene (LiAl(SiO3)2) over a range of external magnetic field H0 wide enough [Formula: see text] to bridge for the first time the gap between pure quadrupole spectra (R = 0) and Zeeman spectra slightly perturbed by quadrupole interactions [Formula: see text]. Experimental results on the resonance frequencies and relative signal amplitudes obtained with an induction type of nuclear resonance spectrometer are described, and are found to be in good agreement with the theoretical predictions given in the preceding companion paper.
A GENERALIZED VARIATIONAL PRINCIPLE FOR TRANSPORT PHENOMENA
Authors: Tauber G. E.
Published: April 2011

A generalized variational principle has been formulated which takes the phonon distribution functions and the external magnetic field into account, is valid for an arbitrary direction of the electric field and polarization of the lattice vibrations, and does not depend on any special form of the energy surfaces. The various transport coefficients, for both thermoelectric and thermomagnetic phenomena, are obtained by the Ritz method in terms of infinite determinants without requiring an explicit solution of the transport equations.
THE TEXTURE OF ZINC AND CADMIUM FILMS DEPOSITED ON FRESH CLEAVAGE FACES OF MICA
Authors: Moorti V. R. Guru , Gharpurey M. K.
Published: April 2011

Zinc and cadmium films condensed from vapor in vacuo on the two sides of mica cleavage exhibit well-matched textures in the corresponding regions on the two sides. In those cases where the deposition is due to the Frenkel mechanism of homogeneous nucleation, there is similarity in the gross features alone. On the other hand, when the condensation is due to the presence of "active" centers of nucleation on the mica surface, there is generally a "one-to-one" correspondence between the crystallites on the two faces.
THE SPECTRUM AND STRUCTURE OF THE HNO MOLECULE
Authors: Dalby F. W.
Published: April 2011

The absorption spectrum of HNO in the region 6500–7700 Å has been photographed on a 35-ft grating. The observed spectrum consists of three bands: an intense one at the long-wavelength end of the spectrum and two weaker bands towards shorter wavelengths. All the bands have extensive rotational structure of the perpendicular type. The spectrum was observed after the flash photolysis of nitromethane, nitroethane, isoamyl nitrite, and mixtures of nitric oxide and ammonia. The "lifetime" of the HNO was about 1/10 second under our experimental conditions. The spectrum of DNO has also been photographed. From the constants obtained from the rotational analysis the molecular geometry has been determined. For the lower electronic state[Formula: see text]For the upper electronic state[Formula: see text]The most probable identification of the observed electronic transition is 1A″ ← 1A′.
THE RELATIONSHIPS BETWEEN THE SECULAR CHANGE AND THE NON-DIPOLE FIELDS
Authors: Whitham Kenneth
Published: April 2011

Using airborne, ground, and repeat magnetic observations in Canada compiled in the isomagnetic and isoporic charts for epoch 1955.0, the drift and decay contributions of the non-dipole field to the observed secular variation have been estimated. The drift rates which produce the minimum residual secular variation were found to be unusually small. It is then confirmed, using the longitude displacement method and isomagnetic data only, that the westward drift of the non-dipole field in recent years in Canada is significantly smaller than the world-wide average. These results clearly demonstrate the large local fluctuations which occur in westward drift.The two different methods were applied to obtain relationships between the Gaussian coefficients in the spherical harmonic analyses of the earth's main field and the secular variation. Calculations show that both methods give the accepted world-wide average value of westward drift, that one half of the world-wide secular variation is produced by westward drift, and in general decay terms are unimportant.
ACCURACY OF OPTICAL PYROMETRY IN THE RANGE 800 °C TO 4000 °C
Authors: Lovejoy D. R.
Published: April 2011

A pair of secondary standard tungsten strip lamps have had a luminance temperature – current calibration, in the range 800 °C to 2200 °C, at a number of national laboratories. An analysis of the calibration results confirms estimates of the accuracy of optical pyrometry in the range 800 °C to 2200 °C and supports the extension of these estimates to 4000 °C. The standard deviation uncertainty of optical pyrometry is shown to be about 1 °C at 800 °C rising to 2 °C at 2200 °C and 10 °C at 4000 °C, being about double this for the calibration of commercial pyrometers unless certain described precautions are taken.The reliability of the secondary standard lamps, when used under well-defined conditions, is confirmed and it is shown that they have a standard deviation calibration uncertainty of about 1 °C for the vacuum-type lamps in the range 800 °C to 1500 °C and 2 °C for the gas-filled lamps in the range 1500 °C to 2200 °C. Most of this uncertainty is due to primary standard optical pyrometer calibration errors. Attention is drawn to the fact that a carbon arc fulfills the requirements of a secondary luminance temperature standard at about 3514 °C.Recent determinations of the gold point and the second radiation constant indicate that the 1948 International Temperature Scale is lower than the thermodynamic scale by an amount varying from 0.8 °C at 800 °C to 12 °C at 4000 °C. This is already greater than the calibration errors of optical pyrometry and, in view of the still greater accuracies presaged by photomultipliers, a revision of the International Temperature Scale is suggested.
THE ELECTRON NEUTRINO ANGULAR CORRELATION IN THE BETA DECAY OF THE FREE NEUTRON
Authors: Robson J. M.
Published: April 2011

The electron neutrino angular correlation coefficient has been measured for the beta decay of the free neutron by measuring the momentum spectrum of the electrons emitted in a restricted angular range from the direction of the recoil protons. Experiments were made for two different angular ranges and yielded a best value for the angular correlation coefficient of +0.07 with an error of ±0.12. This error includes the statistical error in the form of its standard deviation and an allowance for all known systematic errors.
DISCOVERY OF Pr137
Authors: Dahlstrom Carl , Foster J. S. , Thompson A. L.
Published: April 2011

The neutron-deficient isotope Pr137 has been discovered by proton bombardment of natural cerium, chemical separation, and mass determination. Its half-life is 1.5 ± 0.1 hours and the end point of its positron spectrum is 1.7 ± 0.1 Mev. No gamma rays were observed.
SUCCESSIVE DECAYS FROM Pr137 AND Ce137m: DECAY OF ADJACENT PRASEODYMIUM ISOTOPES
Authors: Danby G. T. , Foster J. S. , Thompson A. L.
Published: April 2011

The decay of Pr137 entirely to a 9.0-hour ground state of Ce137 was independently discovered. By allowed electron capture, Ce137 decays predominantly to a low-lying state of La137, with only a 3% branching to a 440-kev excited state. The 440-kev transition is at least predominantly E2 in character.A 34.4-hour isomeric state produced by the La139(p, 3n)Ce137m reaction decays by a 254.5-kev M4 transition to the 9-hour -ground state. A 0.6% branching was found from the isomeric state directly to a small group of apparently high spin states in La137.Studies of mass-separated isotopes confirmed the existence of 1.5-hour Pr137 and 1.0-hour Pr136. The K-capture to positron branching ratios observed in the decay of Pr139, Pr138, Pr137, and Pr136 show that these isotopes decay by allowed transitions to their cerium daughters. Characteristic gamma rays were observed.
THE STAEILITY OF COUETTE FLOW IN AN AXIAL MAGNETIC FIELD
Authors: Niblett E. R.
Published: April 2011

Chandrasekhar's theory of the stability of viscous flow of an electrically conducting fluid between coaxial rotating cylinders with perfectly conducting walls is extended to include the case of non-conducting walls, and it is found that their effect is to reduce the critical Taylor numbers and increase the wavelength of the instability patterns by considerable amounts. An experiment designed to measure the values of magnetic field and rotation speed at the onset of instability in mercury between perspex cylinders is described. The radioactive isotopes Hg197 and Hg203 were used to trace the flow. The results support the theoretical prediction that the boundary conditions can have a large effect on the motion.
PROPERTIES OF CADMIUM SULPHIDE PHOTOCONDUCTIVE CELLS
Authors: Williams R. L.
Published: April 2011

Measurement of the noise spectra of cadmium sulphide photoconductive cells from 10 to 10 Mc/sec has failed to reveal a transition from the 1/f to the 1/f2 noise frequency dependence. This clearly demonstrates a complete lack of dependence of the 1/f noise spectrum on the photoconductive time constant, which is approximately 30 milliseconds.No noise correlation has been observed, indicating a minority carrier lifetime of less than 10−7 seconds.The extreme difference between the minority carrier lifetime and the photoconductive time constant is explained by assuming that most of the recombination takes place at the surface of the film, but that the rate of recombination is controlled by diffusion. Slow diffusion of the minority carriers is a consequence of their very short lifetimes.The noise power and time constants of CdS have been observed to depend on the value of the series resistance used with the cell. The two effects are believed to be related and to arise from the presence of intercrystalline barriers.
SPACE CHARGE RELATIONS FOR THE LOW-FREQUENCY SILENT ELECTRIC DISCHARGE IN HYDROGEN
Authors: Jatar D. P.
Published: April 2011

The current-potential characteristics in hydrogen under the low-frequency silent electric discharge using an all-glass ozonizer are examined from the standpoint of the Child-Langmuir space charge relation and the modified Townsend Werner equation. It is concluded that the three distinct regions in the characteristics correspond to the space-charge-free, the space-charge-limited, and the steady corona regimes.
THE VISIBLE EMISSION SPECTRUM OF Cl2+1
Authors: Rao V. Venkateswara , Rao P. Tiruvenganna
Published: April 2011

Two visible emission band systems attributed to the ionized molecule Cl2+ were studied using the second order of a 21-ft concave grating spectrograph (dispersion 1.25 Å/mm). Rotational analyses have been carried out for six bands of system I and six of system III for which new vibrational analyses have recently been proposed by Haranath and Rao. The rotational analyses of the bands of these two systems are consistent with the vibrational assignments. Rotational constants for the upper and lower states of the two systems have been derived. Both the vibrational and rotational analyses of systems I and III indicate case (c) 1/2–1/2 and 3/2–3/2 transitions respectively for the two systems. Potential energy curves are drawn for the upper and the lower states of each of the two systems. The lower states dissociate into a normal Cl (2P) + Cl+(3P) while the upper states dissociate into a normal Cl (2P) + an excited Cl+ (1D). It is suggested that the lower state of system 111 is probably the normal state of Cl2+ from theoretical and experimental evidence.
PARALLACTIC MEASUREMENTS ON AURORAE OVER CHURCHILL, CANADA
Authors: McEwen D. J. , Montalbetti R.
Published: April 2011

Height measurements on the lower edges of homogeneous and rayed arcs and bands are reported from 404 photographs taken of aurorae over Churchill (58.8° N., 94.2° W.) during the winter of 1957–58 as part of the I.G.Y. programme. The frequency distribution in height of 1975 points measured shows a double peak at 101 and 107 km, and a mean height of 104.8 km. The chief factor affecting height of aurora appears to be that of intensity; the mean height of weak aurorae was found to be 107.7 km, while that of strong aurorae was 100.1 km. No difference in mean height of aurorae before and after midnight was observed. Tidal effects in the upper atmosphere did not appear to affect auroral height greatly. The mean heights of aurorae measured during high and low tide conditions showed no appreciable difference. A mean orientation of 105.5° magnetic azimuth was measured for auroral arcs. Auroral motions with speeds up to 2500 meters per second were observed.
INVESTIGATION OF THE DRIFTS OF THE EFFECTIVE POINT OF RADIO REFLECTION ALONG A METEOR TRAIN
Authors: Rao M. Srirama , Armstrong R. L.
Published: April 2011

The concept of the effective point of radio reflection from a meteor train has been given on the basis of atmospheric turbulence, on a vertical scale of the order of 100 m to 6 km, in the M region. Some experimental evidence has been provided to support the postulate of its drifting along the train, using meteoric body doppler radar records, taken on 30.02 Mc/s at South Gloucester, during the Geminid shower periods of 1948–50. The velocities (Vs) of the above drifts in the case of 90 observations have been calculated, using the ranges of the observed meteors as obtained from the range–time records taken simultaneously on pulsed radar on 32.7 Mc/s at the Metcalfe Road field station (7.5 km distant). It is found that these velocities tend to have higher values in the case of shorter echo durations and vice versa. Theoretical interpretation of the observed results has been attempted. Reasonable assumptions of the ionization distribution along a meteor train and of diffusion rates at different levels in the M region have been made to derive the echo durations from different portions of a meteor train. Variation of these echo durations with position on the train has been taken into account to calculate the theoretical curves of vertical components of Vs vs. total echo durations, in the case of a Geminid shower. The effect of turbulence on echo durations has been taken into account to explain the observed results successfully.
ENERGIES OF GRAIN BOUNDARIES IN SILVER CHLORIDE CRYSTALS
Authors: McCarthy Kathryn A. , Chalmers Bruce
Published: April 2011

The relative energies of grain boundaries in silver chloride crystals have been measured. The measurements were made on tricrystals grown by simultaneously drawing three single crystals vertically from a melt. Tricrystals of three different isoaxial orientations, [Formula: see text], [Formula: see text], and [Formula: see text], were studied. The relative grain boundary energies were measured as a function of the orientation differences between two grains forming a boundary in crystals of each of the orientations given above. From these measurements the following conclusions are drawn: the grain boundary energies of silver chloride follow the equation of Read and Shockley; for small orientation differences, that is, differences less than 10°, the boundary energy is a function of the axial orientation of the grains forming the boundary; for large orientation differences, that is, differences greater than 10°, the boundary energy is not a function of the axial orientation, except when cusps occur; the maximum energy of a boundary made of crystals each with a [Formula: see text] axial orientation equals the maximum energy of a boundary between crystals of [Formula: see text] axial orientations.
HORIZONTAL MOTIONS IN RADAR ECHOES FROM AURORA
Authors: Lyon G. F. , Kavadas A.
Published: April 2011

A systematic motion of 48.2 Mc/sec echoes associated with aurora is found at Saskatoon. The motion is towards the west before midnight and towards the east after midnight, the mean velocity in either direction showing a statistical relation to variations in the earth's magnetic field. No correlation is found between individual echo velocity and magnetic disturbance, and no period of zero velocity is observed. There is also evidence of an ordered relation between motion in the north–south direction and disturbances in the earth's magnetic field.
MEASUREMENT OF THE DIELECTRIC PROPERTIES OF LOW LOSS MATERIALS AT MILLIMETER WAVELENGTHS
Authors: Mungall A. G.
Published: April 2011

Measurement at millimeter wavelengths of the dielectric properties of low loss materials by a free space technique is described. The dielectric constant is determined from the Brewster angle, and the dielectric loss tangent from the attenuation coefficient measured at the Brewster angle of incidence. Results are given for bakelite at wavelengths between 5 and 10 mm. Details of the instrument, which was specifically designed for these measurements, are also given.
THE QUENCHING OF TRIPLET POSITRONIUM BY IONS IN AQUEOUS SOLUTIONS
Authors: Green R. E. , Bell R. E.
Published: April 2011

Measurements of positron lifetimes in aqueous solutions have been performed using a fast time-to-amplitude converter with a resolving time of ~10−9 sec. The lifetime, τ2, of the long-lived component of the complex decay observed in water has been found to decrease when paramagnetic salts are added. The experimental results are interpreted in terms of "pickoff" annihilation to explain the observed τ2 in pure water, and a rapid triplet ↔ singlet conversion process to account for the quenching of the τ2 component. The conversion is caused by the presence of unpaired electrons in the structure of the paramagnetic atoms. Triplet → singlet conversion cross sections have been calculated on the basis of this interpretation and they range from 4.0 × 10−20 cm2 for NdCl3 to 3.8 × 10−18 cm2 for FeCl3.
EXPERIMENTS ON PROCESSING AND MOUNTING OF NUCLEAR EMULSIONS
Authors: Judek B.
Published: April 2011

A mounting procedure for Ilford G.5, 600 μ stripped emulsions which gave very good results on several large and small stacks, totalling about 10 liters of emulsion, is described. Special tests have shown that emulsions can be developed almost immediately after mounting. Delay of processing for a day or longer after mounting offers no special advantage, while it causes fading of the latent image to an extent of about 15%.Experiments on development with a "warm" stage of 50° F indicate a reduction of spurious scattering to about one-half the value usually obtained with a "warm" stage of about 76° F. At the same time the degree of development obtained was comparable with that at 76° F.A better uniformity of development with depth in the emulsion has been obtained by a variation in the usual development procedure.
EFFECTS OF A LIQUID CORE ON THE PROPAGATION OF SEISMIC WAVES
Authors: Duwalo George , Jacobs J. A.
Published: April 2011

Effects of a spherical cavity in an infinite, homogeneous, isotropic elastic solid, containing non-viscous compressible liquid, on the propagation of elastic waves are investigated mathematically. The waves emitted by a simple harmonic point source in the solid are of the types known as SH and P in seismology. The discussion is restricted to the case ka » 1 (ka = 2 π cavity radius/wave length). Series solutions are transformed into contour integrals by Watson's method. Evaluation of these by the method of residues results in expressions describing the P and S components of the diffracted waves.
ROTATIONAL ANALYSIS OF THE β BANDS OF PHOSPHORUS MONOXIDE
Authors: Singh Nand Lal
Published: April 2011

The fine structures of three of the β bands of PO which occur near 3200 Å have been analyzed. The analysis shows that the upper state of this band system is a 2Σ and not a 2Π state as previously believed. The rotational constants of both electronic states have been determined and it is found that the ground state constants, previously determined from the γ bands, are incorrect.
RADIATION AND RECEPTION PROPERTIES OF A WIDE SLOT IN A PARALLEL-PLATE TRANSMISSION LINE: II
Authors: Millar R. F.
Published: April 2011

The study initiated in Part I is continued, with consideration being given to the case in which only a TEM wave is propagated in the parallel-plate region. The reflection and transmission coefficients, and the polar diagram of the radiated field are determined.The amplitude and phase of the propagated wave excited in the line by an incident cylindrical or plane wave are determined by reciprocity arguments.Curves are presented to illustrate the dependence of the field on the slot width and the distance between the parallel plates, for the two field types considered here and in the previous paper.
A METHOD FOR EVALUATING LATTICE SUMS
Authors: Maradudin A. A. , Weiss George H.
Published: April 2011

A rapidly convergent method for evaluating a certain class of lattice sums by the use of asymptotic series is presented, and the method is illustrated by applying it to the evaluation of lattice sums previously studied by Benson and Schreiber.