bluuebunny/crossref_metadata_2025 huggingface dataset:
FORBIDDEN TRANSITIONS IN DIATOMIC MOLECULES: IV. THE a′3Σ+ ← XlΣ+ AND e3Σ− ← X1Σ+ ABSORPTION BANDS OF CARBON MONOXIDE
Authors: Herzberg G. , Hugo T. J.
Published: April 2011

Two examples of forbidden electronic transitions in heteronuclear molecules, 3Σ+ – 1Σ+ and 3Σ− – 1Σ+, are studied in the spectrum of the CO molecule. The bands have been obtained in absorption in the region 1750 to 1230 Å with absorbing paths up to 400 cm-atm., using the fourth and fifth orders of a 3 meter vacuum spectrograph. In most of the 3Σ+ – 1Σ+ bands all four predicted branches are observed. For the 3Σ− – 1Σ+ bands, a somewhat unusual structure is predicted: two branches of O and S form and three branches of Q form. In the best-resolved bands, four branches are observed which closely fit the predicted branches, two of the Q branches being very nearly coincident and unresolved in the present spectra. The rotational and vibrational constants of the upper states, a′3Σ+ and e3Σ− of the two band systems have been determined. Some of these data had previously been obtained from perturbations in other band systems of CO. On the whole, the perturbation data agree satisfactorily with the more precise data obtained directly in the present study.
THE INTENSITY AT THE BOTTOM OF THE FRAUNHOFER D LINES
Authors: Scrimger J. A. , Hunten D. M.
Published: April 2011

The line profiles were measured by scanning a photomultiplier and exit slit in the second order of a 21-ft. grating. The large distortions resulting from finite resolution were evaluated by means of an absorption cell containing sodium vapor with helium at a pressure of 170 mm. This produced an artificial line whose central intensity was known to be zero. By matching its profile carefully to that of the solar line the central intensities of D1 and D2 were found to be (5.0 ± 0.6)%and (4.8 ± 0.6)% in terms of the nearby continuum.
ENERGY AND ANGULAR DISTRIBUTIONS OF PHOTONEUTRONS PRODUCED BY 70-MEV. X-RAYS
Authors: Dixon W. R.
Published: April 2011

The angular distributions of the photoneutrons produced by 70-Mev. X-rays in seven elements have been measured with a zinc sulphide – lucite scintillation detector. For the heavy elements the distributions are essentially isotropic, indicating the predominance of the evaporation process, while for the light elements there is also an anisotropic component peaked at 90°. The energy distributions of the photoneutrons produced in copper and lead targets have been determined with nuclear emulsions. It is shown that most of the neutrons can be attributed to an evaporation process which is governed by a constant nuclear temperature, the temperature found for copper being 1.2 Mev., and for lead being 1.0 Mev. A high-energy tail on the energy distributions is attributed to direct interactions.
THE ZERO-POINT KINETIC ENERGY OF LIQUID HELIUM
Authors: Henshaw D. G. , Hurst D. G.
Published: April 2011

The zero-point kinetic energy of liquid helium has been calculated from the interatomic potential, the latent heat of vaporization, and atomic distributions derived from neutron diffraction measurements. Calculations were carried out for two liquid temperatures and several published interatomic potential functions. The resulting values of the "zero-point temperature" lie between 9.0°K. and 12.6°K.
THE SPECTRUM OF THE Si2 MOLECULE
Authors: Douglas A. E.
Published: April 2011

Two band systems attributed to the Si2 molecule have been excited in a discharge tube. The first of these is a 3Π – 3Π system of red-shaded bands with heads at 3489, 3556, 3626, and 3696 Å. The second is an extensive system of 3Σ–3Σ bands in the visible and near ultraviolet region. High resolution spectra have been analyzed and the rotational and vibrational constants have been determined.
HIGH RESOLUTION RAMAN SPECTROSCOPY OF GASES: V. ROTATIONAL SPECTRA OF ALLENE, ALLENE-d4, AND ALLENE-1,1-d2
Authors: Stoicheff B. P.
Published: April 2011

The pure rotational Raman spectra of allene, allene-d4 and allene-1,1-d2 were photographed in the second order of a 21 ft. grating. Two plates of each spectrum were analyzed yielding the following values for the rotational constants:[Formula: see text]These constants lead to the value r0(C=C) = 1.3088 ± 0.001 Å. Also if a value of r0(C—H) = 1.07 ± 0.01 Å is assumed, then [Formula: see text]. It is noted that the length of the carbon–carbon double bond in allene is significantly shorter than that in ethylene.
SOME EXACT SOLUTIONS OF THE LORENTZ INVARIANT PROBLEM OF THE MOTION OF TWO ELECTRIC FLUIDS
Authors: Gibbons J. J.
Published: April 2011

Methods of generating exact steady-state solutions for the flow of superimposed positive and negative fluids are developed for the cases of linear and cylindrical motion. The two fluids are assumed to be subject only to body forces arising from the total E and B fields. It is shown that the only axially symmetric solutions are of cylindrical symmetry, i.e. rotating spheres or rings of charge cannot satisfy the equations where the two fluids overlap.
A STANDARD OF MUTUAL INDUCTANCE
Authors: Henderson J. T. , Romanowski M.
Published: April 2011

A primary standard of mutual inductance of the Campbell type has been constructed by the National Research Council to serve as an ultimate standard of reference for electrical quantities in Canada. The electrical value is computed from its measured physical dimensions. A detailed description is warranted in view of its national importance. The value of the standard is 0.010,007,24s henry with an error not larger than 13 p.p.m.
CONSIDERATIONS ON THE PRIMARY WINDING OF THE CAMPBELL STANDARD INDUCTOR
Authors: Romanowski M. , Fraser P. A.
Published: April 2011

The effect of the presence of the quartz cylinder on the mutual inductance of the N.R.C. standard is examined using the expression for the energy of the circuit made of the primary and the secondary connected in series. The analysis and the computation show that the volume susceptibility of the quartz, equal to −4π × 0.39 × 10−6 (in m.k.s. rationalized units), produces a decrease of the mutual inductance of the order of 2 parts in 106. In the second section the effect of the finite cross-section of the primary wire is examined. The assumption that the current is concentrated in the central filament of the wire was in several past cases considered as sufficient. The computation given here shows that this effect is not negligible and on the actual N.R.C. standard amounts to 3 or 4 parts in 106.
THE GEOMAGNETIC LATITUDE EFFECT ON THE NUCLEON AND MESON COMPONENT OF COSMIC RAYS AT SEA LEVEL
Authors: Rose D. C. , Katzman J.
Published: April 2011

Measurements have been taken on the changes in intensity of the nucleon and meson components of cosmic rays during a cruise of the Canadian Naval Icebreaker Labrador into the Arctic, through the North West Passage, and circumnavigating the North American Continent. The geomagnetic latitudes covered extend from 18°N. to 89°N. The latitude knee is clearly shown at a geomagnetic latitude of about 52° in the case of the nucleon component and less definitely between 40° and 50° in the case of the meson component. The rigidity of particles arriving in a vertical direction at 52° is 2.1 Bv. and at 45° is 3.7 Bv. Meyer and Simpson have shown that changes in the primary spectrum between 1948 and 1954 probably extend up to these rigidities and such changes should, therefore, be observable at sea level. The longitude effect at low latitudes is clearly shown by differences in intensity between the measurements on the east and west sides of North America. In the case of the meson component, the magnitude of the longitude effect at these longitudes was found to be greater than that shown by Millikan and Neher in 1936. The interpretation of the meson component results above the knee is complicated by difficulties in temperature correction. In the case of the nucleon component, an apparent longitude effect exists above the knee in that there was a small difference in the intensity at high latitudes in the eastern and western parts of the North American Arctic. No satisfactory explanation is offered for this. The diurnal variation of the nucleon component at high latitudes is shown but no unusual features were found. Appreciation is expressed to the Royal Canadian Navy for making these measurements possible.
RADIATION RESISTANCE OF DIPOLES IN AN INTERFACE BETWEEN TWO DIELECTRICS
Authors: Wait James R.
Published: April 2011

Exact expressions are derived for the radiation resistance of electric and magnetic dipoles located in the plane interface between two semi-infinite lossless dielectrics.
TRANSIENT FIELDS OF A VERTICAL DIPOLE OVER A HOMOGENEOUS CURVED GROUND
Authors: Wait James R.
Published: April 2011

Expressions are derived for the transient fields of a short vertical antenna, situated on a smooth spherical conducting earth, and energized by a current which is discontinuous in time. When the antenna current is a linear function of time, the radiation field on a flat perfectly conducting earth is of step-function form. The departure from the step shape of the field is shown to be due to the finite conductivity and dielectric constant of the ground, the induction and static fields of the antenna, and the curvature of the earth.
METEOR ECHO DURATIONS AND VISUAL MAGNITUDES
Authors: Millman Peter M. , McKinley D. W. R.
Published: April 2011

The statistical relation between the radio echo duration and the visual magnitude has been investigated for approximately 3300 meteors observed on the combined Dominion Observatory–National Research Council program at Ottawa. Both echo durations and visual magnitudes were reduced to absolute values, defined as those for a meteor in the zenith at a height of 100 km. For meteors in the absolute magnitude range +5 to −5 a straight line relation exists between log absolute duration and absolute magnitude, longer durations corresponding to brighter meteors. Applying current meteor theory to these data indicates that a meteor of absolute magnitude +5 produces 2 × 1012 electrons per cm. of path length. For Perseid meteors the ratio between ionization produced and visual luminosity is almost constant in the range +5 to −5 absolute magnitude. For other meteors this ratio seems to decrease somewhat for the brighter objects. These results lead to higher electron densities for the bright meteors than had previously been estimated.
THE DECAY OF Re186 AND Re188
Authors: Johns M. W. , McMullen C. C. , Williams I. R. , Nablo S. V.
Published: April 2011

The energies and intensities of 13 gamma rays in Re188 have been measured by studying their external conversion spectra with a high resolution beta-ray spectrometer. An analysis of the beta-ray spectrum reveals groups with end points 2116 kev. (79%) and 1961 kev. (20%), and several low energy groups whose total intensity is of the order of 1%. The observed data can be consistently accounted for in terms of a decay scheme involving the following levels of OS188: 0.0, 155.0, 633, 1086, 1306, 1461, 1765, 1941, and 1958 kev. This scheme is firmly supported by coincidence measurements. The spins of the first three levels listed are 0+, 2+, and 2+ and that of the 1461 kev. level is probably 0+.The decay of Re186 is accompanied by gamma rays of the following energies and quantum intensities: 122.9 kev. (0.6%), 137.2 kev. (10%), 630.8 kev. (0.024%), and 768.2 kev. (0.024%). These values are in good agreement with those quoted in the literature, except for the intensities of the last two radiations.
THE SPECTRUM OF CN IN THE VACUUM ULTRAVIOLET
Authors: Carroll P. K.
Published: April 2011

The spectrum of the CN radical has been investigated in the Schumann region using a three-meter vacuum spectrograph in the fourth order. A hollow cathode discharge through streaming helium, to which a trace of cyanogen was added, was used as source. Three new systems of bands were found in the region 1650–2100 Å. These involve two hitherto unknown states: a 2Σ state designated by E, which gives rise to the transitions E2Σ → X2Σ and E2Σ → A2Π, and an inverted 2Δ state designated by J, which gives rise to the transition J2Δ → A2Π. Rotational analyses of the bands have been made and the molecular constants evaluated. The new data, although not decisive, support the higher value (8.2 ev.) for the dissociation energy of CN.
THE EFFECT OF GROWTH CONDITIONS UPON THE SOLIDIFICATION OF A BINARY ALLOY
Authors: Tiller W. A. , Rutter J. W.
Published: April 2011

This investigation provides both a theoretical and an experimental analysis of the factors which affect the mode of solidification of a binary alloy. These factors are: (i) the concentration of solute in the melt (C0); (ii) the rate of solidification (R); (iii) the temperature gradient in the melt at the solid–liquid interface (G). Extremely high purity lead was produced by zone refining and, from this material, crystals containing known concentrations of tin, silver, and gold were grown under a range of well-controlled growth conditions. The mode of solidification was investigated by a careful study of the change in appearance of the solid–liquid interface with a change in growth conditions. For a crystal containing a specific C0 of solute it was observed that (a) the transition from a smooth interface to a cellular interface occurred at a critical ratio of G to R; (b) the width of the cells varied inversely as G and inversely as R; (c) the transition from a cellular interface to a dendritic interface exhibited a large orientation dependence, and for a constant orientation breakdown occurred at a critical ratio of G to [Formula: see text]. The experimental observations confirm both the existence of a solute-rich layer of liquid adjacent to the solid-liquid interface and its quantitative features. From this agreement with theory the diffusion coefficients of tin, silver, and gold in liquid lead at 327 °C. are determined. This work serves to illustrate the effect of extremely small amounts of particular solutes upon the development of substructures during solidification. A technique is proposed for obtaining a measure of the purity of low impurity content alloys.
OBSERVATIONS ON STARS AND HEAVY PRIMARIES RECORDED IN EMULSIONS FLOWN IN VIKING ROCKET NO. 9
Authors: Yagoda Herman
Published: April 2011

Methods for the preparation of fresh nuclear emulsions for use in the study of cosmic radiation by rocket exposures are described. Shattering and mechanical damage is minimized by substituting transparent plastics for the glass support. By casting the emulsion on a temporary microporous medium such as plaster of Paris, emulsions 2 mm. thick can be dried in about six days without appreciable loss of sensitivity. Strong, thin-walled housings for the emulsions are described. The star production rate in emulsions flown in the mesosphere to a peak altitude of 217 km. is 1180 ± 280 cc.−1 d.− 1 and is 1.45 ± 0.17 times greater than similar measurements in the stratosphere (30 km.). The augmentation of nuclear disintegrations can be accounted for by the opening up of the effective solid angle for star-producing radiation during the rocket flight. Energetic stars with three or more shower particles record with a frequency of 278 ± 30 cc.−1 d.−1, about three times greater than in a balloon flight at the same geomagnetic latitude. For large showers Ns = 6, the N/P ratio is about 0.17. The observational ratio of M to H nuclei based on a spectrum of 238 heavy primary tracks is 2.66. When corrected for fragmentation in surrounding matter this ratio is reduced to 2.5 ± 0.5. The omnidirectional flux of heavy primaries [Formula: see text] at the top of the atmosphere is 7.62 meter−2 sec.−1 sterad.−1. An analysis of the zenith angle distribution of the heavy primaries shows that the unidirectional flux is in fair agreement with geomagnetic theory for zenith angles < 60°. The directional flux for θ > 60° is about two times greater than predicted by theory.
THE POSSIBILITY OF A PHASE CHANGE IN NUCLEAR MATTER
Authors: Trainor L. E. H. , Dixon W. R.
Published: April 2011

The possibility is discussed that Livesey's hypothesis of a constant nuclear temperature at low excitations is indicative of a phase change in nuclear matter.
GROWTH TWINS IN GERMANIUM
Authors: Bulling G. F. , Rutter J. W. , Tiller W. A.
Published: April 2011

The occurrence of growth twins in germanium was investigated as a function of the thermal, constitutional, and crystallographic conditions of solidification; it was found to be very markedly dependent upon these growth conditions. In every case the nucleation of a twin could be traced to a condition of supercooling, either absolute or constitutional, during solidification. A new type of substructure was also observed to form under certain growth conditions.
THE PHOTODISINTEGRATION OF OXYGEN NUCLEI INTO FOUR ALPHA-PARTICLES
Authors: Dawson W. K. , Livesey D. L.
Published: April 2011

A total of 323 four-prong stars found in photographic plates exposed to bremsstrahlung of maximum energy 70 Mev. have been identified as due to the disintegration of O16 nuclei into four alpha-particles. The excitation function of the reaction exhibits pronounced peaks at 22.5 Mev. and 32.5 Mev. as well as maxima at intermediate energies, and the integrated cross sections for various energy ranges have been estimated. The mechanism of the process has been investigated and most of the disintegrations proceed via known excited levels in C12 and various states of Be8.
HIGH-ENERGY FORBIDDEN β-RAY TRANSITIONS FROM Cs134 (2.3 yr.), Co60 (5.3 yr.), Sc46 (84 d.), and Hg203 (47.9 d.)
Authors: Wolfson J. L.
Published: April 2011

Beta-ray transitions of energies 1478 ± 6 kev. from Co60 (5.3 yr.) and 1475 ± 6 kev. from Sc46 (84 d.) were observed with intensities of (1.0 ± 0.2) × 10−4 and (3.6 ± 0.7) × 10−5 β-rays per disintegration respectively. Forbidden spectrum shapes were obtained for both transitions. No evidence was obtained for the β-ray transition of energy 1451 kev. from Cs134 (2.3 yr.), nor for the transition of energy 473 kev. from Hg203 (47.9 d.), and upper limits of 5 × 10−5 and 3 × 10−4 β-rays per disintegration respectively are placed upon the intensities of these transitions. The log f0 t values are > 14.5, 14.0 ± 0.1, 13.0 ± 0.1, and > 11.3 for the transitions referred to from Cs134, Co60, Sc46, and Hg203 respectively.
THE RADIATION FORCE ON A SPHERICAL OBSTACLE IN A CYLINDRICAL SOUND FIELD
Authors: Embleton T. F. W.
Published: April 2011

The corresponding problems of the radiation forces acting on a spherical obstacle in a plane or spherical progressive sound field have been examined previously by King (Proc. Roy. Soc. (London), A, 147:212.1934) and Embleton (J. Acoust. Soc. Amer. 26:40. 1954) respectively. In these cases the sound field and scattering obstacle both have symmetry of revolution about the line joining the center of the obstacle to the origin of the sound field, but for a cylindrical sound field there exists only a much lower degree of symmetry. A general expression has been obtained for the radiation force in terms of the complex amplitudes of spherical harmonics required to synthesize the incident sound field—for the cases of greatest symmetry this reduces to the simpler expression previously obtained. The first 20 non-zero amplitudes have been evaluated for a cylindrical sound field and it is shown that the force is one of attraction near to the source, becomes zero at a certain distance, and is a force of repulsion at a greater distance. Qualitatively, this force is the same as for spherical waves but for any size of obstacle and frequency of the sound field the point of zero force is always nearer to the source in a cylindrical wave.
EVAPORATION NEUTRONS FROM COSMIC RAY NUCLEAR INTERACTIONS IN VARIOUS ELEMENTS
Authors: Geiger K. W.
Published: April 2011

Production of evaporation neutrons from nuclear interactions by cosmic rays is investigated in C, Al, Fe, Cu, Pb, and Bi. Boron trifluoride counters in a paraffin moderator in which the element under study is placed serve to detect the evaporation neutrons. A cosmic ray telescope allows the consideration of ionizing neutron-producing particles separately and it is found that of the total neutrons 14.6% are produced by ionizing particles. The mean neutron multiplicities are worked out and they show an increase with the two-thirds power of the atomic weight of the element in which the interactions take place. Also, the rate of interactions is calculated and this gives the relative interaction cross-sections which are found to increase slightly more with atomic weight than expected if the cross-section is geometric. An estimate of the intensity of the N-component is made and discussed in connection with measurements published by other authors.
THE BEHAVIOR OF FERROMAGNETICS UNDER STRONG COMPRESSION
Authors: Stacey F. D.
Published: April 2011

Specimens in the form of thin disks have been subjected to strong compression simultaneously with high magnetic fields by means of a new design of permeameter, with which their magnetizations have been measured. Magnetization curves extending to saturation have been plotted for a number of materials at (non-hydrostatic) pressures up to 10,000 atmospheres. The most interesting result is the strong increase in saturation magnetization shown by nickel and the nickel–copper alloys.
METEORIC ECHOES OBSERVED SIMULTANEOUSLY BY BACK SCATTER AND FORWARD SCATTER
Authors: McKinley D. W. R. , McNamara A. G.
Published: April 2011

Simultaneous observations of back-scatter and forward-scatter meteoric echoes have been made by means of a high-power 33 Mc./sec. pulse transmitter at Ottawa, with identical receiving systems at Ottawa and at Scarboro, 337.8 km. distant. Two-way transmissions, employing a low-power transmitter at Scarboro, were also used to measure absolute time delays. The approximate position of each meteor was plotted from the observed time delays, which enabled corrections to be applied to the echo durations for variations in antenna patterns and other factors, and which also determined the forward-scatter angle, [Formula: see text], for each meteor. In the majority of cases an enhancement was observed in the forward-scatter duration relative to the back-scatter duration. The data were divided into a short-duration or underdense group and a long-duration or overdense group. Assuming a theoretical forward-scatter enhancement proportional to [Formula: see text], it was found that the exponent, m, was 1.73 for the underdense group and 1.13 for the overdense group.
SPIN ECHOES IN ALCOHOLS AND DERIVATIVES
Authors: Crawford G. J. B. , Foster J. S.
Published: April 2011

The spin echo technique has been employed to measure the relative chemical shifts and the indirect spin–electron–spin coupling constants between protons at different structural sites in ethyl, propyl, isopropyl, butyl, isobutyl, and amyl alcohols and certain of their derivatives at a Larmor frequency of 29.0 Mc./s. The separation between the two r-f. pulses applied to the sample increases regularly in accurately known steps which are controlled electronically. Thus the frequencies modulating the echo envelope have been readily measured with a precision as high as 4% in favorable cases. Relative chemical shifts found by slow passage experiments have been checked with higher accuracy, particularly for the primary alcohols. Encouraged by the implications of these earlier data, we have here analyzed the longer hydrocarbon chains on the basis of the theoretical computations of Hahn and Maxwell for only two groups of non-equivalent protons. This more precise investigation confirms the assumptions made as to where the major shifts and couplings do and do not exist in the molecular structures. In the halide molecules, it is found that the observed relative chemical shifts are linearly proportional to the paramagnetic fields arising from the valence orbits of the halogens polarized by the external field. Evidence for the particular J-coupling to the hydroxyl group in the alcohols suggests that this bond is effectively stronger in the heavier molecules which are only slightly soluble in water.
THE OSCILLATING SPHERE AT LARGE AMPLITUDES IN LIQUID HELIUM
Authors: Benson C. B. , Hallett A. C. Hollis
Published: April 2011

Measurements of the damping of the oscillations of a sphere which decay from an initial deflection ~ 10 radians show that two critical amplitudes, denoted by [Formula: see text] and [Formula: see text], may be defined in liquid helium II. The decrement is constant at amplitudes below [Formula: see text] (a few tenths of a radian), and is caused by the damping due to the viscosity of the normal fluid. [Formula: see text] is found to be proportional to the square root of the period of oscillation. Above [Formula: see text] the decrement increases, the superfluid becoming involved in the motion, until it attains another constant value, which is attributed to the viscosity of a single fluid whose density is equal to the total density (ρn+ρδ) of liquid helium II. At a larger amplitude [Formula: see text] (~ 2 radians) the decrement begins to increase linearly with amplitude, and this behavior, which is also found in liquid helium I and in helium gas at 4 °K., is attributed to the onset of turbulence. Reynolds numbers calculated at [Formula: see text] are ~ 200 for helium II, helium I, and helium gas at 4 °K.
CORRELATION TENSORS IN STATISTICAL HYDRODYNAMICS IN POROUS MEDIA
Authors: Scheidegger A. E.
Published: April 2011

The author's statistical theory of flow through porous media, based upon an extremely simple model in which pressure fluctuations are being neglected, has been criticized because velocity correlation tensors had not been introduced as dynamical variables. It is shown in the present paper that the introduction of such variables is not useful in the author's theory. This is due to the particularly simple nature of the model employed and does not imply that the use of correlation tensors may not lead to something useful in other conceivable statistical theories.
A DOUBLE MAGNETIC FIELD MODULATION PARAMAGNETIC RESONANCE SPECTROMETER
Authors: Buckmaster H. A. , Scovil H. E. D.
Published: April 2011

A high sensitivity, wide or narrow band, double magnetic field modulation type paramagnetic resonance spectrometer operating at a wavelength of 1.25 cm. for use at liquid helium temperatures (4 °K.) is described. The spectrometer employs a transmission type, cylindrical resonant cavity excited in the H111 mode. The magnetic field is modulated simultaneously at 60 c.p.s. and 465 kc. A resonance from 10−11 mole of diphenyl trinitro phenyl hydrazyl has been observed with a signal-to-noise ratio of 2:1 at 290 °K. in wide band operation (8 kc.) indicating that a sensitivity of O(10−15) mole should be possible in narrow band operation (1 c.p.s.) at 4 °K. because of its inherent high stability.
A SCHEMATIC MODEL FOR (p, xn) CROSS SECTIONS IN HEAVY ELEMENTS
Authors: Jackson J. D.
Published: April 2011

A schematic model for the description of (p, xn) reactions in heavy elements is presented. Reactions are divided into two steps, a prompt multiple collision process, followed by an evaporation stage. The various prompt processes are given by the results of Monte Carlo calculations, while the evaporation processes are described by a simplified model assuming constant nuclear temperatures and only neutron evaporation. The resulting (p, xn), and to a minor degree (p, pxn), cross sections are compared with the experimental data of Bell and Skarsgard (1956) in the energy range up to 100 Mev. With an average neutron binding energy of around 7.3 Mev., a nuclear temperature of about 1.8 Mev., and a nuclear radius of 8.0 × 10−13 cm., a reasonable over-all fit can be made to the data for Pb206, Pb207, Pb208, and Bi209. Characteristic fluctuations in the experimental results for the (p, 2n), (p, 3n), and (p, 4n) reactions for all targets seem to be attributable to variations in the total reaction cross section, and are not reproduced by the present model.
A HOMOGENEOUS DIELECTRIC SPHERE AS A MICROWAVE LENS
Authors: Bekefi G. , Farnell G. W.
Published: April 2011

A homogeneous dielectric sphere illuminated by a small external source of electromagnetic radiation will be free, because of its special symmetry, from all off-axis aberrations such as coma and astigmatism. If the only monochromatic aberration, namely spherical aberration, is not too excessive or if it is partially corrected by a suitably designed source, a sphere could be used for purposes of rapid scanning of a microwave beam through an angle of 360° of arc without moving the lens. This possibility was investigated by computations based on geometrical optics and on the diffraction theory of optical aberrations. The results suggest that a sphere of fairly small refractive index and less than about 30 wavelengths in diameter will produce a good diffraction image of a point source. Methods are also discussed of designing appropriate sources for use with larger spheres.
THE STRENGTHS, WIDTHS, AND SHAPES OF INFRARED LINES: I. GENERAL CONSIDERATIONS
Authors: Benedict William S. , Herman Robert , Moore Gordon E. , Silverman Shirleigh
Published: April 2011

A discussion is given of methods by which the strengths, widths, and shapes of spectral lines may be derived from measurements obtained with spectrometers whose resolving power is sufficient to separate individual spectral lines but is insufficient to portray accurately the true line contour. The Lorentz shape for collision broadened lines is taken as a first approximation to the true line shape for most of the discussion. Numerous corrections that should be taken into account in interpreting experimental data are included. These arise from instrumental effects, overlapping of the individual lines, and deviations from the Lorentz shape. The three types of measurements discussed in some detail are the measurements of the "equivalent width," of the apparent breadth of a line at high optical density, and of the apparent extinction of a line or group of lines at the troughs between lines and in the wings. It is shown how these various types of measurements can be combined to yield the line strength, width, and shape.
THE STRENGTHS, WIDTHS, AND SHAPES OF INFRARED LINES: II. THE HCl FUNDAMENTAL
Authors: Benedict William S. , Herman Robert , Moore Gordon E. , Silverman Shirleigh
Published: April 2011

The methods described in Part I are applied in detail to the determination of strengths, widths, and shapes of the vibration–rotation lines of the 1–0 bands of HCl35 and HCl37 observed at 300°K. The variation of the line strengths with rotational quantum numbers is compared with theory to yield a value of the ratio of the permanent electric dipole moment to the product of the effective charge and the equilibrium internuclear distance of + 0.988 ± 0.022. The band strength was found to be 130 cm−2 atm−1 which should be good to ~ 5%. A marked variation of line width with rotational quantum number has been found which follows approximately the Boltzmann population distribution. This result is compared with a theory that considers resonant dipole–dipole and billiard ball interactions. The line widths were found to vary from ~ 0.25 cm−1 atm−1 for J = 3 to ~ 0.07 cm−1 atm−1 for J = 13. Evidence is obtained that at distances greater than ~ 1.5 cm−1 from the line centers the absorption is greater than is given by the Lorentz line shape. In the wings of the lines the absorption is better represented by a line shape varying as (ν –ν0)−η where η ~ 1.8.
THE REFLECTION OF SLOW ELECTRONS FROM TANTALUM AND COPPER
Authors: Hobson J. P.
Published: April 2011

Targets of tantalum and copper on tantalum have been bombarded by electrons with energy 0–40 ev., and the ratio of the number of back-scattered to incident electrons measured. Particular emphasis has been placed on the range 0–10 ev. of primary energy where elastic reflection is dominant. The reflection coefficient for tantalum in this range was found to decrease monotonically as the primary energy fell, approaching a value less than 0.05 as the energy approached zero. This result differs from that of Warnecke below 3.7 ev. The reflection coefficient of copper was found to contain maxima and minima below primary energies of 25 ev. in general agreement with the results of Farnsworth.
PRODUCTION AND PROPERTIES OF C15
Authors: Douglas R. A. , Gasten B. R. , Mukerji Ambuj
Published: April 2011

Uniform thin C14 targets on 2500 Å nickel backings were prepared in a discharge tube containing acetylene (enriched to 28.8% C14). A NaI (Tl) crystal was used to measure the yield of C15 (2.25 ± 0.05 sec. half life) from C14(d, p)C15 from Ed = 1.3 to 3.0 Mev. A 7.5 ± 1.5 sec. activity was also observed, presumably N16 produced by C14(d, γ)N16. The C15 gamma-ray spectrum indicates only a 5.3-Mev. transition. A plastic scintillator was used to measure the C15 beta spectrum. End-point energies of 9.5 ± 0.3 and 4.5 ± 0.2 Mev. with a branching ratio of 4 to 1 favoring the lower energy component were observed. The results are consistent with a spin and parity assignment of 1/2(+) for the C15 ground state.
ABSOLUTE PAIR PRODUCTION CROSS SECTION OF LEAD AT 2.76 MEV.
Authors: Standil S. , Moore R. D.
Published: April 2011

A value has been obtained for the absolute pair production cross section of lead for the 2.76 Mev. gamma rays of Na24. A collimated beam of these gamma rays was made to fall on a specially constructed target and the positrons produced in the target were detected by counting two-quanta annihilation events by means of two scintillation spectrometers in coincidence. The strength of the Na24 source was measured by a coincidence counting technique and the counter detection efficiency for annihilation radiation was measured with a calibrated Na22 source. The effect of absorption of the 0.511 Mev. annihilation radiation in the target was measured in a separate experiment. The value obtained for the cross section was 2.38 ± 0.62 barns.
ON FULLY DEVELOPED TURBULENT FLOW IN CURVED CHANNELS
Authors: Marris A. W.
Published: April 2011

Formulae for the radial distribution of velocity and vorticity for the case of fully developed turbulent flow in the channel between concentric and infinitely long cylinders are developed on a similarity vorticity transfer theory, by postulating an Eulerian mixing length function dependent on both position and radius of curvature. The theoretical results obtained for the mean velocity distribution across the channel compare satisfactorily with existing experimental data when the curvature dependent parameters are given appropriate numerical values.
FERMI DIAD 10°0 AND 02°0 OF NITROUS OXIDE
Authors: Rao K. Narahari , Nielsen Harald H.
Published: April 2011

Measurement of the fine structure of the bands ν1 and 2ν20 of nitrous oxide has led to an evaluation of the centrifugal stretching constants of the Fermi diad 10°0 and 02°0. It was found that as compared to the value in the ground state, the change in the centrifugal stretching constant of the 02°0 level is much more than in the 10°0 level. This result has been discussed in relation to the theory of Nielsen, Amat, and Goldsmith (1956). The following revised values have been obtained for some of the molecular constants of N214O16:[Formula: see text]
HALF-LIFE DETERMINATION OF SOME RADIONUCLIDES
Authors: Merritt W. F. , Campion P. J. , Hawkings R. C.
Published: April 2011

The half-lives of the following nuclides have been determined by absolute counting techniques using a 4π beta proportional counter. The period over which the observations were made is indicated in brackets. The errors quoted are the statistical counting errors.[Formula: see text]A review of previous determinations is included.
NUMERICAL ANALYSIS OF A UNITARY PARTICLE MODEL
Authors: Kaempffer F. A. , Kennedy Edith M.
Published: April 2011

A classical unitary field model describing a family of electrically uncharged heavy particles is analyzed numerically. A reasonable mass spectrum is obtained. Limitations of the model are stated.
MULTILAYER PROBLEMS IN THE SPHERICAL HARMONICS METHOD
Authors: Davison B.
Published: April 2011

In applying the spherical harmonics method to multilayer problems it is necessary to invert certain matrices. It is shown, for the cases of plane and spherical symmetry, that these inverse matrices can easily be written down explicitly, so that there is no need for numerical matrix inversion.
THE EMISSION SPECTRUM OF AlF IN THE VACUUM ULTRAVIOLET
Authors: Naudé S. M. , Hugo T. J.
Published: April 2011

Two vacuum ultraviolet band systems of aluminum monofluoride, the B1Σ+–X1Σ+ and C1Σ+–X1Σ+ systems, are described. The rotational analyses of a few bands in each system are given and the rotational and vibrational constants of the X1Σ+ and B1Σ+ electronic states are determined. Accurate Te−values for the A1Π, B1Σ+, C1Σ+, and D1Δ states are given.
THE SPECTRUM OF SILICON HYDRIDE
Authors: Douglas A. E.
Published: April 2011

The 0–0, 1–0, 2–1, and 2–2 bands of the 2Δ–2Π band system of SiH have been photographed under high dispersion and analyzed. The vibrational and rotational constants have been determined and the dissociation energy has been found to be 3.19 ± 0.25 ev. A list of SiH lines which may occur as interstellar absorption lines is given.
THE FREEZING POINTS OF HIGH PURITY METALS AS PRECISION TEMPERATURE STANDARDS: I. PRECISION MEASUREMENTS WITH STANDARD RESISTANCE THERMOMETERS
Authors: McLaren E. H.
Published: April 2011

The techniques and difficulties encountered in measuring temperatures to the highest precision with platinum resistance thermometers are discussed. It is shown that the relative drift of the resistance coils in the Mueller resistance bridge used for these measurements is less than a part per million per year. The intrinsic resistance of a platinum thermometer is comparatively unstable, and results showing some effects of cold work and heat treatment on several thermometers are given.As each precision temperature determination involves the resistance of the thermometer at the triple point of water, extensive measurements have been carried out to obtain information on: (a) the reproducibility of temperature in particular cells, (b) the variation in temperature among cells, and (c) the long term stability of cell temperatures.The limiting uncertainties in temperature measurements due to variation in the bridge, the thermometers, and the triple point cells are each of the order of 10−4 °C.
PROPERTIES OF GALLIUM INDIUM ANTIMONIDE
Authors: Blakemore J. S.
Published: April 2011

Electrical conductivity and Hall effect are measured for p-type specimens of polycrystalline GaSb.InSb with impurity concentration about 1017 cm.−3. Analysis of these data suggests that μn/μp = 11, and that the intrinsic gap varies linearly with temperature from 0.265 ev. at 0° K. Measurement of the photoconductive limit at various temperatures shows that the gap widens on heating, though the electrical data seem difficult to reconcile with the large gradient of +1.1 × 10−3 ev./°C. indicated by the optical data.
SELECTIVE REFLECTION FROM MERCURY VAPOR AT HIGH PRESSURES
Authors: Welsh H. L. , Galt J. A.
Published: April 2011

Selective reflection from mercury vapor in the region of the 2537 Å resonance line was investigated at pressures up to 340 atm. using reflection cells of special design. The results were interpreted on the basis of the classical theory of reflection from an absorbing medium. By fitting calculated curves to the experimental reflection contours, values of the oscillator strength, f, and the damping constant, γ, were determined. The f values so obtained are density-dependent and at high pressures are approximately equal to one half the value for the free atom. As predicted by theory, the damping constant varies directly as the density of the atoms in the vapor. This result contradicts the earlier work of Welsh, Kastner, and Lauriston (1950) in which it was concluded that γ varies as the square root of the density. A subsidiary reflection maximum was observed at 2540 Å; it is attributed to Hg2 molecules which occur in relatively large concentrations at high densities. Some preliminary observations on the selective reflection at the 1850 Å resonance line were made up to 4.4 atm.
INFLUENCE OF FOREIGN GASES AT HIGH PRESSURES ON THE SELECTIVE REFLECTION FROM MERCURY VAPOR
Authors: Welsh H. L. , Galt J. A.
Published: April 2011

The influence of the foreign gases hydrogen, helium, nitrogen, and argon on the selective reflection from mercury vapor at 2537 Å was studied at pressures up to 1500 atm. The results were interpreted on the basis of the classical theory of reflection from an absorbing medium. The damping constant was found to vary linearly with foreign gas density as predicted by collision broadening theory. Frequency shifts and collision diameters determined from selective reflection data agree fairly well with values measured in absorption by other workers.
IONIC MOBILITIES IN ARGON AND HELIUM LIQUIDS
Authors: Williams R. L.
Published: April 2011

The mobilities of ions and electrons have been measured in liquid argon at 90° K., and in liquid helium from 4.2° to 1.4° K. The electron behavior in liquid argon can be explained in terms of gas kinetic theory, while the positive ion behavior in both liquids cannot. Stokes' law predicts the ionic behavior at the boiling points of the two liquids. Electrons in liquid helium have very small mobilities, approximately one-quarter the value for the positive ions, suggesting a wide departure from the electron behavior in argon. Below 2.19° K. both the electronic and ionic mobilities become temperature and electric field dependent.
MOMENTUM DISTRIBUTION OF METALLIC ELECTRONS BY POSITRON ANNIHILATION
Authors: Stewart A. T.
Published: April 2011

The angular correlation of photons from the two-photon decay of positrons has been measured for positrons annihilating in some 34 elements, mostly metals. These data give the momentum distribution of photons and hence of the center of mass of the annihilating electron–positron pairs. The momentum distributions are discussed in terms of the velocity dependence of the annihilation probability. It is concluded that the observed momentum distributions are primarily the momentum distributions of the conduction electrons in the metals. A higher momentum component is observed, which is attributed to ion core effects.
A "FREE SPACE" ABSORPTION CELL FOR MICROWAVE SPECTROSCOPY
Authors: Costain C. C.
Published: April 2011

The absorption cell consists simply of a pyrex tube with a polystyrene lens and microwave horn at each end to couple to the standard microwave components. The lenses also serve as the vacuum windows. The attenuation at 8.5 mm. wavelength is 3.4 db. for a 250 cm. cell. Since there are no metal surfaces, this type of cell is very suitable for the investigation of reactive molecules. It can readily be employed in a high temperature microwave spectrometer for the investigation of corrosive substances with low vapor pressures, or in a Zeeman modulation spectrometer for the study of free radicals.
THERMAL AND ELECTRICAL CONDUCTIVITY OF RHODIUM, IRIDIUM, AND PLATINUM
Authors: White G. K. , Woods S. B.
Published: April 2011

Measurements are reported of the thermal and electrical conductivities of the transition elements Rh, Ir, Pt in a state of high purity; the rapid rate of decrease of the "ideal" thermal and electrical resistivities with temperature, particularly in Rh and Ir, suggests that s–d transitions are not a dominant resistive mechanism at low temperatures in these metals, in contrast to palladium, iron, and nickel, which were studied previously. The electrical resistivity of platinum is in general agreement with the earlier results of de Haas and de Boer (1934); the quadratic dependence on temperature observed below about 10° K. suggests that electron–electron collisions may well be an important factor in this metal.
THE ELECTRICAL RESISTANCE OF SOME METALS AND ALLOYS BELOW 1° K.
Authors: Dugdale J. S. , MacDonald D. K. C.
Published: April 2011

Measurements of electrical resistance below 1° K. are described, including experiments to estimate the thermal contact resistance between the paramagnetic salt and gold wires which were subsequently used as secondary thermometers. The resistance of a dilute copper alloy, a lithium–magnesium alloy, and a sodium specimen was measured. No change was found in the resistance of sodium which might be correlated with the specific heat anomaly previously reported by Rayne. The resistance below the minimum in the gold and copper specimens showed a marked contrast in behavior below 1° K. No minimum was found in the resistance of the lithium–magnesium alloy.
A FAST AURORAL CAMERA
Authors: Montalbetti R.
Published: April 2011

A movie camera is described which photographs an auroral display at a speed of one or more frames per second. The fast optical system and wide angular field of view are obtained with an f/0.71 objective and a spheroidal mirror. The camera has been found very useful in the study of auroral motions.
ON THE PRODUCTION OF SINGLE CRYSTALS OF NAPHTHALENE AND ANTHRACENE
Authors: Lipsett F. R.
Published: April 2011

Furnaces for the growth of naphthalene (m.p. 80 °C.) and anthracene (m.p. 217 °C.) crystals from the melt by the Bridgman method are described and discussed. The advantages of long furnaces are emphasized. A seeding technique may be used to produce long crystals, and has been successful in producing naphthalene crystals [Formula: see text] feet long. A technique for polishing the crystals which gives flat, smooth surfaces is described. Methods of determining the orientation of the crystals by cleavage and by examination of the isogyres or birefringence in a polarizing microscope are given. A simple method for producing anthracene crystals by recrystallization from solution in N,N-dimethylformamide is given, and apparatus for producing very thin sublimation crystals of anthracene is described. The procedures may also be employed to produce mixed crystals.
A HIGH-FREQUENCY 500-KILOVOLT COCKCROFT-WALTON ACCELERATOR
Authors: Lorrain Paul , Béique René , Gilmore Paul , Girard Paul-Emile , Breton Alain , Piché Pierre
Published: April 2011

The 500-kilovolt accelerator described is of the Cockcroft–Walton type and is operated at a frequency of 32 kc. It is pressurized for compactness. The circuit comprises 24 stages and is terminated by an inductive load which increases the output voltage by a factor of 1.5. The rectifier filaments are heated by utilizing the current flowing through the stray capacitances of the rectifiers. The circuit calculations are given and the design is described briefly.
THE EMISSION OF IONIZING RADIATION DURING A SPARK DISCHARGE
Authors: Prowse W. A. , Bainbridge G. R.
Published: April 2011

A high voltage pulse lasting 0.35 microsecond is applied to a pair of delay lines, so that two pulses can be picked up from adjustable points of connection on the lines. One is applied to an irradiating gap and the other to a longer test gap, the gaps being so arranged that only mid-gap irradiation occurs. The sparking probability, P, of the test gap is used to indicate the presence of ionizing radiation. Variations of P with the time interval between the two pulses are recorded. They indicate that ionizing radiation is emitted in repeated short flashes. Photographic observations support this view.
HIGH RESOLUTION RAMAN SPECTROSCOPY OF GASES: VIII. ROTATIONAL SPECTRA OF ACETYLENE, DIACETYLENE, DIACETYLENE-d2, AND DIMETHYLACETYLENE
Authors: Callomon J. H. , Stoicheff B. P.
Published: April 2011

The pure rotational Raman spectra of acetylene (C2H2), diacetylene (C4H2 and C4D2), and dimethylacetylene (C4H6) have been photographed with a 21-ft. grating spectrograph. The rotational constants were found to be B0(C2H2) = 1.1769 cm−1, B0(C4H2) = 0.14689 cm−1, B0(C4D2) = 0.12767 cm−1, and B0(C4H6) = 0.1122 cm−1. An analysis shows that r0(C—H) in diacetylene is shorter than in acetylene and cyanoacetylene; in dimethylacetylene at least one of the carbon–carbon bonds is longer than in the closely related molecule methylacetylene.