bluuebunny/crossref_metadata_2025 huggingface dataset:
INVESTIGATIONS ON THE DIFFUSION OF MINORITY CARRIERS FROM A POINT ON SILICON
Authors: Champness C. H.
Published: April 2011

The field-free diffusion of minority carriers injected at a point in silicon has been studied and the time from injection to the maximum of the collector signal due to the arriving carriers measured for various emitter–collector distances. Firstly, it was found that for 2-ohm-cm, 6-microsecond, n-type material the time to maximum was proportional approximately to the emitter–collector spacing raised to the power 1.2 for flat surfaces and to the power 1.6 for 3- and 6-degree wedge samples. The power 1.6 was also found for a 17-degree wedge of 120-ohm-cm, 100-microsecond, p-type silicon. Secondly, decay times following the maxima appeared to increase with emitter–collector spacing. No adequate two-surface theory is available but comparison with a one-surface theory revealed serious disagreements. It would appear that the results may be explained qualitatively by assuming that the effective lifetime is dependent on the excess carrier density and decreases as the emitter point is approached.
ON THE RELATION BETWEEN THE OLD AND THE NEW DEFINITION OF THE INTERNATIONAL METRE
Authors: Hart K. H. , Baird K. M.
Published: April 2011

In October, 1960, the Eleventh General Conference of Weights and Measures adopted as the new definition of the International Metre, 1,650,763.73 wavelengths in vacuum of the unperturbed .606 μ line of Kr86. The present paper reports measurements, in terms of the new definition, on four copies of the metre which were well known in terms of the former International Metre prototype. They indicate no significant discontinuity in the metre, as a result of the transition to the new definition, and they demonstrate the accuracy to which the metre based on the old definition was realized in practice.
GAMMA-RAY ANGULAR CORRELATIONS FROM ALIGNED NUCLEI PRODUCED BY NUCLEAR REACTIONS
Authors: Litherland A. E. , Ferguson A. J.
Published: April 2011

Two general procedures for the measurement and analysis of angular correlations of gamma radiations from nuclear reactions are described which have wide applications in nuclear spectroscopy for the determination of spins and gamma-ray multipolarities. Cases can be studied by these methods when the reaction proceeds through a compound state too complex to allow the usual analysis to be made, for example where several levels overlap or where direct interaction is dominant. The basis of these procedures is to exploit the simplifications brought about by making the reacting system axially symmetric. A sharp gamma-ray-emitting state formed in such a system can be regarded as aligned and described in terms of a relatively small number of population parameters for the magnetic substates. In the first procedure, a state Y* is prepared by a nuclear reaction X(h1h2) Y* in which h2 is unobserved. The state Y* has axial symmetry about the beam axis. From coincidence angular correlation measurements of two cascade gamma rays from Y*, the unknown population parameters for Y* together with the nuclear spins and gamma-ray multipolarities can be determined. In the second procedure, h2 is measured in a small counter at 0° or 180° relative to the incident beam. It is then shown that the quantum numbers of the magnetic substates of Y* which can be populated do not exceed the sum of the spins of X, h1, and h2. In cases where the sum of the spins does not exceed [Formula: see text], the angular correlation of the gamma rays from the aligned state depends only upon the properties of the states in the residual nucleus. Theoretical expressions for angular correlations from aligned states are given, together with a method whereby existing extensive tables of coefficients can be used to calculate them. The results of two recent experiments are discussed as examples.
A PSYCHROMETER TABLE FOR HEAVY WATER HUMIDITIES
Authors: Niven C. D.
Published: April 2011

A psychrometer table for use in atmospheres humidified with heavy water has been constructed by calculation from data on the vapor pressure and latent heat of vaporization of heavy water, between 10° and 40 °C. The relative humidity is quite markedly lower in the low temperature end of this range when heavy water is used instead of ordinary water, for the same wet and dry bulb readings.
A 1Σ−–3Πr SPECTRUM OF SiO
Authors: Verma R. D. , Mulliken R. S.
Published: April 2011

A new 1Σ−–3Πr (case a) spectrum is identified in the region 4200–4300 Å for the SiO molecule. The rotational analysis of the spectrum gives the following constants for the lower and upper states in cm−1.[Formula: see text]A discussion of electron configurations is given.
LOW-LYING ENERGY LEVELS IN Cl-35
Authors: Storey R. S. , Oleksiuk L. W.
Published: April 2011

The reaction Cl35(p,p′γ)Cl35 has been observed by the gamma radiation arising from the first two excited levels of chlorine-35. Excitation functions for these radiations were measured for a range of proton energies from 2.3 to 3.25 Mev. Many sharp resonances are observed, of which a dozen are prominent. Angular distributions of the gamma rays from the 1.22-Mev and the 1.76-Mev excited levels of Cl35 have been measured over six resonances. The distribution functions, together with additional measurements by other investigators, yield spin assignments of 1/2 and 5/2 for the levels at 1.22 and 1.76 Mev respectively.
THEORY AND DESIGN OF A COAXIAL SUPPORTING BEAD MADE OF COMPOSITE DIELECTRICS
Authors: Owyang Gilbert H.
Published: April 2011

The effect due to the presence of a single supporting bead made of composite dielectrics in a coaxial line is being studied. A formula correlating the standing wave ratio caused by the bead and the physical parameters of the bead is derived. A bead of this type may be designed to have very low voltage standing wave ratio (VSWR) over a very wide band of frequency. A typical design using quartz and air as dielectrics is given, and the calculated VSWR is below 1.003 over a bandwidth whose maximum to minimum frequency ratio is as high as 13:1.
THE CRYSTAL STRUCTURE OF K2TiCl6
Authors: Bland J. A. , Flengas S. N.
Published: April 2011

The crystal structure of K2TiCl6 was determined from the X-ray diffraction pattern. K2TiCl6 is cubic, space group Fm3m, and has a cell side of 9.792 ± 0.005 Å. The interatomic distances are: Ti–Cl, 2.35 ± 0.03 Å, and K–Cl, 3.46 ± 0.03 Å.
VERTICAL DISTRIBUTION OF SODIUM IN THE UPPER ATMOSPHERE
Authors: Bullock W. R. , Hunten D. M.
Published: April 2011

The sodium twilight has been observed over the period October 1958 to December 1959 with a birefringent photometer. Abundances and vertical distributions have been found for 120 twilights. The abundance variation is similar to that found previously but is more nearly symmetrical about the solstices. A small seasonal variation in peak height is found, 3 to 5 kilometers with maximum in March. In general, changes in abundance cannot be correlated with changes in distribution; however, a few exceptions to this were found in June and July, when a large overnight increase in abundance accompanied a large decrease in the height of the whole distribution.
RADIO-FREQUENCY EREAKDOWN CONTROLLED BY DRIFT OF ELECTRONS IN AN INHOMOGENEOUS MAGNETIC FIELD
Authors: Shepherd L. T. , Skarsgard H. M.
Published: April 2011

A study has been made of r-f. breakdown in which the controlling loss mechanism arises from the drift of electrons in an inhomogeneous magnetic field. The study was carried out using a toroidal system with parallel r-f. electric and steady magnetic fields. An approximate average-electron theory of drift-controlled breakdown is presented. Experimental measurements of breakdown r-f. electric field versus magnetic field were made at various pressures from 1.25 to 6.0 × 10−3 mm of Hg, using hydrogen and helium gases. A radio frequency of 8 Mc/sec was used. Magnetic fields up to 2000 gauss were employed. The r-f. breakdown field was found to vary as the inverse square root of the magnetic field as predicted by the theory.
THE PRESSURE PULSE PRODUCED BY A LARGE EXPLOSION IN THE ATMOSPHERE
Authors: Weston V. H.
Published: April 2011

The pressure pulse produced by a large explosion in the atmosphere is investigated. The explosion is represented in terms of the excess pressure and normal velocity on a closed surface, outside of which the hydrodynamical equations are linearized. The pulse is represented in terms of a Fourier transform of the associated harmonic frequency problem, for which a ring-source Green's function is obtained in terms of an expansion of the discrete modes. It is shown that the excess pressure may be represented in terms of an integral (containing the Green's function) over the surface surrounding the source. The gravity wave portion of the pressure pulse at the ground is computed for various ranges from the source, which is located at various altitudes, and for three models of the atmosphere. In calculating the head of the pulse a new asymptotic technique is introduced which gives very good results for intermediate and long ranges.
GAMMA-ACTIVE FALL-OUT IN ONTARIO 1958–60
Authors: McNeill K. G. , Trojan O. A. D. , Dawson D. J.
Published: April 2011

Measurements have been made of the Cs137 content of man and of milk and of the Zr95 and Cs137 activity of air-borne dust. They show that the Cs137 content of man went through a maximum of 67 μμc/g K in the fall of 1959, and that the Cs137 content of milk reached a low of 7.5 μμc/g K in September 1960. The results suggest stratospheric and tropospheric residence times of 2 years and 2 months respectively.
ON MEASUREMENT OF THERMAL CONDUCTIVITY AT HIGH TEMPERATURES
Authors: Laubitz M. J.
Published: April 2011

A method is given for exact mathematical analysis of linear heat flow systems used in measuring thermal conductivity at high temperatures. It is shown that a popular version of such a system is very sensitive to the alignment of its components, which seriously limits the temperature range of its satisfactory use.
THE CRYSTAL STRUCTURE OF Bi2Te2Se
Authors: Bland J. A. , Basinski S. J.
Published: April 2011

The crystal structure of Bi2Te2Se has been determined by X-ray single crystal methods. The unit cell is trigonal, space group [Formula: see text] with hexagonal cell edges a = 4.28 ± 0.02 Å, c = 29.86 ± 0.10 Å, and there are three formula units per unit cell. The structure is of the C33 type and a comparison is made with other C33 structures, Bi2Se3, Bi2Te3, and Bi2Te2S. An important common feature of these compounds is that the atom on the center of symmetry has a relatively large contact distance with each of its six Bi neighbors.
WAVES IN A RAREFIED IONIZED GAS PROPAGATED TRANSVERSE TO AN EXTERNAL MAGNETIC FIELD
Authors: Watanabe Tomiya
Published: April 2011

Waves being propagated in a rarefied and fully ionized gas and transverse to an external magnetic field have been studied, particularly hydromagnetic waves. Three modes of waves, in which the perturbed magnetic field is parallel to the external magnetic field, are found to be propagated. In a high-frequency limit, they tend to electromagnetic waves, electron sound waves, and ion sound waves. In the condition that the Alfvén velocity is greater than the ion sound velocity but smaller than the light velocity, the last mode tends to a hydromagnetic wave in the low-frequency limit. The other two modes of waves can be propagated only at frequencies higher than the critical frequencies, both of which almost equal the electron plasma frequency. The condition that hydromagnetic waves should be attenuated severely due to collisions between electrons and ions has been derived.
PROTON SPIN–LATTICE RELAXATION IN POLYATOMIC GASES
Authors: Bloom M. , Lipsicas M. , Muller B. H.
Published: April 2011

The proton spin–lattice relaxation time T1 has been measured in gaseous samples of methane, ethylene, and ethane as a function of pressure at room temperature and also at 193° K for methane. In the pure gases T1 is proportional to density, p, at low densities indicating that intramolecular interactions couple the spin systems to the lattice, as is the case in hydrogen gas. T1/p at low densities gives information on the mean square angle through which the molecules are rotated per collision. Relaxation due to paramagnetic O2 is observed at higher densities when oxygen gas is added as an impurity. The relaxation probability per collision with an oxygen molecule is about 5 times larger for the ethylene–oxygen system than for the other two systems studied. This anomaly is discussed in terms of the theory of Oppenheim and Bloom. It is shown that a study of the temperature dependence of T1 due to O2 impurities provides a new way of obtaining detailed information on the Lennard–Jones parameters for the interaction between O2 and the solvent molecules.
A BALLOON-BORNE SPECTROMETER FOR STUDY OF THE AIRGLOW BEYOND 2.0 μ
Authors: Noxon J. F. , Jones A. Vallance
Published: April 2011

An account is given of the design, construction, and flight of a balloon-borne infrared spectrometer intended for the study of the night airglow spectrum in the 2.2- to 3.5-μ region. This region is not accessible from the ground because of the strong thermal emission from the lower atmosphere. The spectrometer employed a 64 × 64 mm plane diffraction grating and a liquid-oxygen-cooled PbS detector. The spectral slit width was 700 Å and the noise-equivalent differential brightness was about 2 × 10−8 watt∙cm−2∙sterad−1∙micron−1. The observations permitted an upper limit of about 700 kR (kilorayleighs) to be placed on the zenith brightness of the 1–0 OH band; this value is very close to that predicted by Chamberlain and Smith. No emission was observed between 2.3 and 2.7 μ. This establishes an upper limit on the zenith brightness of emission features in this region at 200 kR, for features narrow compared to the spectral slit width, and at about 3000 kR/micron for the differential brightness of any continuous emission. The general design of spectrometers for this wavelength region is considered and a discussion is given of improvements suggested by the results of this experiment.
NEW EMISSION BANDS OF ,
Authors: Tanaka Y. , Namioka T. , Jursa A. S.
Published: April 2011

Thirty-eight new bands of nitrogen were observed in the region 2050–3070 Å in an a-c. condensed discharge of neon mixed with a small amount of nitrogen. It was determined that these bands result from the transition [Formula: see text] of [Formula: see text].
SELF-DIFFUSION IN BODY-CENTERED CUBIC ZIRCONIUM
Authors: Kidson G. , McGurn J.
Published: April 2011

Self-diffusion coefficients of crystal-bar zirconium have been measured between 1500 °C and 1100 °C, using radioactive Zr95 as a tracer. The results may be represented by[Formula: see text]The pre-exponential factor is about three orders of magnitude smaller than that measured in most close-packed systems and the activation energy about one-half that anticipated from an empirical correlation with the melting point. The results, however, are similar to those of a few other recently studied body-centered cubic (BCC) systems, and agree quantitatively with work in the Soviet Union on zirconium. There is considerable evidence that the diffusion process occurs via vacant lattice sites.
ANGULAR DISTRIBUTION OF FAST PHOTONEUTRONS
Authors: Baker R. G. , McNeill K. G.
Published: April 2011

The angular distributions and the yields of the high-energy neutrons emitted in photodisintegration have been studied by silicon detectors (25 elements) and aluminum detectors (6 elements). With the silicon detectors systematic variations are apparent in the coefficient a2 of W(θ) = a0(P0 + a2P2), and these variations are interpreted in terms of the Wilkinson shell model of photonuclear reactions.
CROSS SECTIONS OF (p,pxn) REACTIONS IN Au197
Authors: Kavanagh T. M. , Bell R. E.
Published: April 2011

Cross sections of (p,pn), (p,p2n), and (p,p3n) reactions in Au197 have been measured by the activation method for incident proton energies up to 86 Mev. The curves of cross section as a function of energy have similar shapes for the three reactions. They rise from apparent thresholds at about 16, 21, and 30 Mev, respectively, to peak values of 180, 145, and 150 mb at proton energies about 30 Mev higher than the apparent threshold energies. The cross sections are much larger than those predicted from the statistical and cascade-evaporation theories, and they are interpreted in terms of two-body collisions in the diffuse surface of the target nucleus. A combination of these results with measured (p,xn) cross sections yields an approximation to the total reaction cross section of a heavy nucleus.
THE RATIO OF THE RESONANCE INTEGRAL TO THE THERMAL NEUTRON CROSS SECTION FOR Sm152
Authors: Walker W. H. , Green R. E.
Published: April 2011

Cadmium ratio measurements have been made in similar lattice positions in ZEEP with thin foils of Sm152 and gold. From a comparison of these cadmium ratios we find[Formula: see text]If gσ0 is assumed to be 212 ± 12 barns, then I′ = 3100 ± 200 barns. On the assumption that only one resonance in Sm152, at 8 ev, contributes appreciably to both the resonance integral and the thermal cross section, it follows that g = 1 and that Γ, the width at half-maximum of the total cross section resonance, is 193 ± 5 milli-ev. Because of the appreciable disagreement between this value and one reported earlier, a new time-of-flight measurement of the resonance parameters has been made, and it is reported in the next paper (Chrien 1961).
RESONANCE PARAMETERS FOR THE 8-ev LEVEL OF Sm152
Authors: Chrien R. E.
Published: April 2011

The joint BNL–AECL Fast Chopper Facility operating at the NRU reactor at Chalk River has been used to determine the resonance parameters of the 8-ev level of Sm152. Using a resonance shape analysis method, the following parameters were obtained: E0 = 8.02 ± 0.02 ev, Γ = 205 ± 15 milli-ev, and Γn = 79 ± 3 milli-ev. With these values, a reduced resonance capture integral of 3090 ± 220 barns is calculated, in agreement with recent cadmium ratio measurements.
THE EFFECTS OF ENERGETIC TRAPPED PARTICLES ON MAGNETOSPHERIC MOTIONS AND IONOSPHERIC CURRENTS
Authors: Fejer J. A.
Published: April 2011

It is shown that the temporary distortion of a previously stable belt of energetic charged particles, trapped in the earth's magnetic Held, results in a system of ionospheric currents and magnetospheric motions. The currents are caused by the charge separation which occurs in the course of the subsequent adiabatic motion of the energetic particles. The resulting current system closely resembles the well-known Ds current system. The polarization fields, which drive these currents, give rise to magnetospheric motions similar to those of Axford and Hines and the implications of their work then also result. The distortion of the belt could be caused either directly, by the introduction of a new group of trapped particles mainly on the day side of the magnetosphere, or indirectly, through the relatively sudden compression of the earth's field on the day side, caused by the arrival of a neutral stream of charged particles from the sun.
TRANSITION RANGES FOR THREE-DIMENSIONAL WAKES
Authors: Magarvey R. H. , Bishop Roy L.
Published: April 2011

The motions set up in a liquid due to the passage of a drop of an immiscible liquid have been examined for a number of liquid–liquid systems. Wake configurations corresponding to Reynolds numbers between 0 and 2500 have been photographed, and the transition ranges between the various wake configurations have been determined. Several liquid–liquid systems were used in obtaining data on wake patterns, and it was found that identical patterns correspond to approximately the same Reynolds numbers regardless of the system. However, the exact transition number cannot be determined for the general case as drop deformations depend on the physical characteristics of a particular system. The range of Reynolds numbers corresponding to a transition from one wake pattern to another is somewhat less than 20.
SUBSTRUCTURES AND DISLOCATIONS PRODUCED DURING SOLIDIFICATION OF ALUMINUM
Authors: Biloni Heraldo
Published: April 2011

The substructure and the dislocation arrangement produced during polycrystalline solidification of 99.99% aluminum has been studied using the decanting method for the interruption of the solidification. Etching techniques to reveal individual dislocations and the method of thin epitaxial layers of aluminum oxide to reveal changes in impurity concentration have been employed simultaneously. The development of the structure towards the interior of the solid was studied by successive electrolytic polishings. In this way it was possible to show that the "cell substructure" formed by dislocations originates in areas where "microsegregation" of impurities has occurred. Towards the interior of the solid a dislocation rearrangement into a "macromosaic" substructure which is closely related to the cellular substructure occurs. At the same time a substructure of "macrosegregation" occurs, arising from the original grain boundaries. The results are interpreted in the light of recent theories of solidification.
THE AZIMUTHAL DISTRIBUTION OF ULTRA-HIGH FREQUENCY RADAR ECHOES FROM AURORA
Authors: Kelly P. E. , Hansen D. R. , Forsyth P. A.
Published: April 2011

The distribution in range and azimuth of auroral echoes obtained with an ultra-high frequency radar at Prince Albert is examined. Such distributions may be controlled (i) by the effect of volume integration in the auroral configurations, (ii) by the geographical distribution of aurora, and (iii) by aspect sensitivity of the auroral scatterers. With the radar parameters chosen for this experiment, (i) can be neglected. Of the remaining two effects, (ii) appears to be more important in the period immediately before local midnight and (iii) in the period immediately following local midnight.
GENERAL FORMULA FOR THE SECOND VIRIAL COEFFICIENT
Authors: Kranendonk J. Van
Published: April 2011

A simple derivation is given of the quantum mechanical expression for the second virial coefficient in terms of the scattering phase shifts. The derivation does not require the introduction of a quantization volume and is based on the identity R(z)−R0(z) = R0(z)H1R(z), where R0(z) and R(z) are the resolvent operators corresponding to the unperturbed and total Hamiltonians H0 and H0 + H1 respectively. The derivation is valid in particular for a gas of excitons in a crystal for which the shape of the waves describing the relative motion of two excitons is not spherical, and, in general, varies with varying energy. The validity of the phase shift formula is demonstrated explicitly for this case by considering a quantization volume with a boundary the shape of which varies with the energy in such a way that for each energy the boundary is a surface of constant phase. The density of states prescribed by the phase shift formula is shown to result if the enclosed volume is required to be the same for all energies.
ON THE STATISTICAL PROPERTIES OF SOME TRANSPORT EQUATIONS
Authors: Scheidegger Adrian E.
Published: April 2011

It is shown that, whenever a system is a linear combination of a large number of fluctuating component systems and in the "large" system a certain quantity is a constant of the motion, under equilibrium conditions that quantity is canonically distributed in the component systems and, under non-equilibrium conditions (assuming linear regression of the fluctuations and microscopic reversibility), the quantity in question is subject to a diffusivity equation with a symmetric diffusivity tensor. Application of the above to porous media hydrodynamics immediately yields the equations for miscible displacement which were laboriously obtained earlier from a special statistical model. Similarly, the corresponding equations for suspended sediment transport in rivers and for the mixing of a pollutant in air are shown to be the result of an application of the above general statement. Finally, the theory is also applied to the inertial frequency range in the statistical theory of turbulence.
STUDIES IN CHROMATOGRAPHIC TRANSPORT: I. A SIMPLIFIED THEORY
Authors: Tudge A. P.
Published: April 2011

A simplified but accurate treatment of the theory of adsorption chromatography is presented. The resulting transport equations (which apply to single and multiple adsorbates) are easy to comprehend and apply. Several useful methods are discussed for determining quantitatively the transport of concentration shocks.
VALUES OF THE TRANSPORT COEFFICIENTS IN A PLASMA FOR ANY DEGREE OF IONIZATION BASED ON A MAXWELLIAN DISTRIBUTION
Authors: Shkarofsky I. P.
Published: April 2011

Values are presented for the electronic conductivity for any degree of ionization, radio frequency, and d-c. magnetic field strength, and various electron speed power law variations of the electron collision frequency with neutral particles. Also, the other transport coefficients, such as electron current due to electron density gradients and temperature gradients, and energy flow due to an electric field and due to density gradients and temperature gradients, are tabulated.The analysis is based on substitution of the usual series expansion of Laguerre polynomials into the Fokker–Planck equation for Coulomb collisions and into the Boltzmann equation for electron collisions with neutral particles. For Coulomb effects, the expressions are the same as those derived by Landshoff. Collisions of electrons with neutral particles are included in addition to ions, and a-c. electric fields are treated as well as d-c. magnetic fields. In the limit of a completely ionized gas, the results also agree with those of Spitzer and Harm and of Kaufman. For a slightly ionized gas, the results are compared with Allis' treatment and with calculations using the Dingle integrals. It is found that the Laguerre convergence is inadequate for large angular frequencies when the power law is less than −2 and for small angular frequencies when the power law is greater than 1.The final results can be put in a form which yields two factors, multiplying, respectively, the average collision frequency and radian frequency, to give correct results from simple equations. These factors are usually of order one, and are functions of three parameters, proportional to angular frequency, ratio of electron–neutral to ion averaged collision frequency, and ion charge number.
THE RAMAN EFFECT IN GASEOUS HYDROGEN AT HIGH PRESSURES
Authors: May A. D. , Degen V. , Stryland J. C. , Welsh H. L.
Published: April 2011

The Raman spectrum of hydrogen as a pure gas and in mixtures with helium and argon was studied in the pressure range 100 to 2000 atmospheres at room temperature. Frequency shifts and half-widths of the vibrational Q1 lines and the rotational S0(0) and S0(1) lines were measured at a series of gas densities with a high-dispersion grating spectrograph. The perturbations in ωe and B0 are represented as power series in the density with linear and quadratic terms. The linear term for Δω0 is positive for H2–He, slightly negative for H2, and more negative for H2–A. These results are discussed in terms of an anharmonic oscillator model for the H2 molecule, a polarizability model for the dispersion forces, and the classical pair distribution function. The rotational lines show additional perturbations which are not accounted for in this treatment.
STEREO-PROJECTION SYSTEMS FOR AURORAL HEIGHT MEASUREMENTS
Authors: Shepherd G. G. , Paulson K. V. , Nilson J. A.
Published: April 2011

In the past, auroral heights have been obtained analytically from parallactic photographs. Even though much of the calculation can be replaced with graphical aids, the method is still slow, and somewhat indirect. This paper discusses two stereo-projection systems from which auroral heights can be scaled directly. These and other methods are compared and discussed.
SCINTILLATION SPECTRA FROM THICK SOURCES
Authors: McNeill K. G. , Green R. M.
Published: April 2011

Graphs are presented showing the variation of different characteristics of scintillation spectra when the thickness of the source is altered. Correlation curves between the valley-to-peak ratio and the other characteristics enable tests to be made to decide whether or not changes such as the apparent change in resolution of a spectrum from the resolution obtained with a point source is due to the thickness of the source or to the presence of secondary gamma rays.
POLAR-CAP ABSORPTION FOLLOWING THE SOLAR FLARE OF JULY 16, 1959
Authors: Ziauddin Syed
Published: April 2011

The polar-cap absorption event following the solar flare of July 16, 1959, is examined. Short-term recoveries of the cosmic noise level, associated with auroral disturbances, were observed at Saskatoon and Ottawa during the PCA event. It is suggested that these recoveries were due to a magnetic screening mechanism resulting from the interaction of the aurora producing plasma with the geomagnetic field.
A PROPOSAL TO USE MICROWAVE CAVITIES TO STUDY THE SURFACE PROPERTIES OF HIGH DENSITY PLASMAS
Authors: Curzon F. L. , Howard Roger
Published: April 2011

It is suggested that the resonant properties of a cylindrical microwave cavity containing a highly conducting axial plasma rod could be used to obtain information about the dynamic properties of such a plasma. Two applications of the method are considered: an investigation of electrically exploded wires, and a study of the dynamics of the conventional z-pinch during its initial stages.
YOUNG'S MODULUS FOR SEA ICE
Authors: Langleben M. P.
Published: April 2011

A study is made of the dependence of Young's modulus for small samples of sea ice on their brine content. Young's modulus is determined from the velocity of ultrasonic waves through the samples and the brine content from their salinity and temperature. It is found that, over a range of brine content of about 0.01 to 0.1 as a fraction of the total volume, Young's modulus decreases linearly with increasing brine content. Its value is 10.0 × 1010 dyne cm−2 when the brine content is 0 and 6.5 × 1010 dyne cm−2 for a brine content of 0.1.
THE RAMAN SPECTRA OF LIQUID AND SOLID H2, D2, AND HD AT HIGH RESOLUTION
Authors: Bhatnagar S. S. , Allin Elizabeth J. , Welsh H. L.
Published: April 2011

The Raman spectra of liquid (~18° K) and solid (~2° K) n-H2, p-H2, n-D2, o-D2(80%), and HD were photographed with a reciprocal linear dispersion of 3 to 6 cm−1 per mm. The S0 rotational lines show broadening of a few cm−1 but the Q1 vibrational lines are very sharp. The S0(0) transition of p-H2 and o-D2 is a triplet of sharp lines, but the corresponding transition in HD is not split. The vibrational frequencies in the liquid are lowered by 7 to 9 cm−1 and in the solid by 8 to 11 cm−1 from the gas values. The Raman spectrum of p-H2 has been discussed in detail by Van Kranendonk. In the present communication the vibrational shifts in the various solids are correlated by representing them as the sums of shifts due to dispersion forces, overlap forces, and vibrational coupling.
THE A-C. CONDUCTIVITY OF AIR AT TEMPERATURES OF 300–12,000° K IN THE PRESENCE OF A STATIC MAGNETIC FIELD
Authors: Shkarofsky I. P.
Published: April 2011

The a-c. conductivity is calculated for high temperature air as a function of gas temperature (300–12,000° K), gas density (1 to 10−3 times atmospheric), angular radio frequency, and cyclotron frequency. It is shown that the simple conductivity matrix applies between 6000–8000° K, depending on gas density.
LATTICE DYNAMICS OF CALCIUM FLUORIDE: PART II. THERMAL EXPANSION OF CALCIUM FLUORIDE
Authors: Ganesan S. , Srinivasan R.
Published: April 2011

With the model which explained the specific heat, the thermal expansion of calcium fluoride is calculated. Using the data on the temperature variation of the Raman line and the elastic constant C44, the Gruneisen parameter γi = −∂log ωj/∂log V is calculated as a function of ω for the optical and acoustic branches along [100], [111], and [110] directions. The thermal expansion coefficient is evaluated using Houston's method. The calculated values are in good agreement with the measured values of Valentiner and Wallott. Calculations reveal that γ0 = βV/χCv will increase with decreasing temperature, the rise starting in the liquid hydrogen region of temperature. The thermal expansion of this crystal can be measured up to liquid helium temperature to verify the result of these calculations.
REFRACTION SPECTRUM OF GASES IN THE INFRARED INTENSITIES AND WIDTHS OF LINES IN THE 2–0 BAND OF HCl
Authors: Jaffe J. H. , Kimel S. , Hirshfeld M. A.
Published: April 2011

Intensities and widths of lines in the 2–0 band of HCl have been determined from the refraction spectrum. A hollow prism refractometer was used together with a monochromator of high resolving power. Fairly elaborate corrections for instrumental effects were applied to the observations. A band intensity of 3.68 cm−2 atm−1 was obtained. The vibration–rotation constant θ was found to be 0.97. Both these values agree well with recent results for HCl obtained from the absorption spectrum.
COLLISION-INDUCED ABSORPTION OF SUBMILLIMETER RADIATION BY NON-POLAR ATMOSPHERIC GASES
Authors: Heastie R. , Martin D. H.
Published: April 2011

The recent development of spectroscopic techniques for extreme infrared frequencies, below 100 cm−1, has enabled us to observe collision-induced absorption in non-polar gases, viz. oxygen, nitrogen, air, and helium–argon mixtures. This absorption results from the modulation of the distortion dipole moment of each pair of colliding molecules by their rotational and translational motions. It is of the kind observed previously at higher frequencies by Kiss, Gush, and Welsh using hydrogen gas. By making measurements at pressures up to 120 atmospheres, the absorption coefficients have been determined over the frequency range 30–100 cm−1.Attention is drawn to the possibilities that such processes may play a role in atmospheric energy balance and might give rise to significant attenuation if beams of infrared radiation were used for communications.
RADAR ANGELS IN THE LOWER TROPOSPHERE
Authors: Hay D. R. , Reid W. M.
Published: April 2011

A study of radar angels at 6800 Mc/s has been carried out at London, Canada, over a period of 1 year. Examination of the clear-air reflections from heights between 300 and 1500 meters above the vertically directed radar has shown that persistent angels occur for surface air temperatures between 30° and 50° F, and that transitory angels are present for surface temperatures above 20° F that are outside of this range. The maximum incidence of angels increases with type of air mass in the order cA, mA, mP, mT, although the most common duration is approximately the same in these air masses. If the angel is due to reflection at a horizontal flat stratum, the power reflection coefficient of the stratum lies between 10−16 and 10−14 for transitory angels and is as large as 10−11 for persistent angels. It is shown that transitory angels may arise through eddy mixing in the lower troposphere when refractivity contrasts of about one part per million occur, but that the reflecting stratum must be no more than a few centimeters in depth. It appears that persistent angels are associated with a high concentration of moisture at the ground, but their physical origin is not clear.
THE TRANSVERSE STERN–GERLACH EXPERIMENT
Authors: Bloom Myer , Erdman Karl
Published: April 2011

It is shown theoretically in this paper that if a beam of neutral spin [Formula: see text] particles incident along the z axis is passed through an inhomogeneous, time-dependent magnetic field of the form[Formula: see text]the beam is split into two beams in the x–y plane when the resonance condition, ω = γH0, is satisfied. The properties of the beams are similar to those obtained in the ordinary Stern–Gerlach experiment. They represent spins in the two eigenstates of Sx in a co-ordinate system rotating at the Larmor frequency about the s axis. For particles of angular momentum [Formula: see text], the beam would be split into 2J + 1 beams. For atoms with unequally spaced energy levels Ei and eigenfunctions ψi in the field H0k, two beams are split off from the main beam when the resonance condition hω = Ei–Ej is satisfied. For an initially un-polarized beam, these two beams have eigenfunctions (1/√2)(ψi ± ψj). Magnetic resonance measurements similar to those made using the Rabi modification of the Stern–Gerlach experiment may be performed with the transverse Stern–Gerlach experiment. For charged particles of spin [Formula: see text] the resonance frequency is γH0–ωc where ωc is the cyclotron frequency. The transverse Stern–Gerlach experiment may be used to measure the magnetic moments of charged particles and an experiment on free electrons is being carried out. Magnetic resonance spectroscopy of ions may be studied with this technique. Another interesting application is in the production of beams of polarized nuclei. Since this may be done with nuclei in ions, it may be possible to produce polarized beams of high intensity in a form useful to nuclear physics experiments.
A CALORIMETRIC DETERMINATION OF THE HALF-LIFE OF THORIUM-230 AND A CONSEQUENT REVISION TO ITS NEUTRON CAPTURE CROSS SECTION
Authors: Attree R. W. , Cabell M. J. , Cushing R. L. , Pieroni J. J.
Published: April 2011

The half-life of Th230 (ionium) has been measured by a calorimetric method and was found to be 75,200 years with a standard error of ± 1,600 years.In the light of this measurement, previously published values for the 2200 m/sec neutron capture cross section and the resonance capture integral (from 0.5 ev to ∞) of Th230 have been amended to 22.7 ± 0.6 barns and 996 ± 40 barns respectively.
DIFFUSION IN MULTICOMPONENT METALLIC SYSTEMS: V. INTERSTITIAL DIFFUSION IN DILUTE TERNARY AUSTENITES
Authors: Kirkaldy J. S. , Purdy G. R.
Published: April 2011

A statistical calculation of the interstitial diffusion flux in a face-centered cubic lattice containing one dilute interstitial component and one substitutional component leads to a relation between the on-diagonal and off-diagonal diffusion coefficients,[Formula: see text]where the [Formula: see text]'s are pair interaction energies and N is the mole fraction. Alternatively, we may combine the thermodynamic relation obtained by neglecting thermodynamic forces due to off-diagonal chemical potential gradients,[Formula: see text]with a nearest-neighbor, regular solution calculation of the thermodynamic activities to obtain the same result.The latter thermodynamic relation is put to the experimental test for the ternary systems Fe–C–Si and Fe–C–Mn by substituting empirical thermodynamic data and comparing with values of D12/D11 obtained by means of a "transient equilibrium" diffusion experiment. In both systems the deviations lie within the experimental and analytical errors.
MEASUREMENT OF γ-RAY DIFFRACTION ANGLES TO ± 0.02 SECOND OF ARC WITH A DOUBLE FLAT CRYSTAL SPECTROMETER
Authors: Knowles J. W.
Published: April 2011

An optical method is described for the precision determination of the relative angle between the diffraction planes of two crystals of a double flat crystal spectrometer. An angular precision, probable error ± 0.02 second of arc, is achieved. Measurement of relative angles are made by reference to a standard ruled scale. Absolute angles are determined by combining these measurements with measurements of the optical geometry. The factors which influence the precision measurements are discussed in detail. It is concluded that γ-ray energies between 0.5 and 2 Mev can be compared with a precision of a few parts in 105.
REALIZATION OF LONG-TERM MAGNETIC STABILITY OF 10−5 PER MONTH FOR A PERMANENT MAGNET ASSEMBLY
Authors: Zingery W. L. , Wirt T. M. , Belland A. , Reeves T. V.
Published: April 2011

An experimental study was directed toward the realization of long-term permanent magnet stability of 10−5 per month. This degree of stability of an inhomogeneous magnetic field was an order of magnitude beyond any previous measurement. Novel instrumentation of the required long-term precision was conceived and developed. Data are presented which evaluate the long-term behavior of various magnet materials and processes. By utilization of the inherent stability offered by higher coercive force materials and by accelerating the magnetic aging through processing, the required stability was achieved.The event of assembly of two magnets into a magnetic circuit was found to induce long-term instability. Processing after assembly wiped out the history of assembly. Proper processing before assembly stabilizes against the assembly effect, but improper processing may lead to even greater instability. The stabilizing processes include high- and low-temperature cycling, a-c. field demagnetization by several methods, and the use of soft iron semikeepering.
THE TOTAL INTERNAL CONVERSION COEFFICIENT OF THE 279-kev TRANSITION FOLLOWING THE DECAY OF Hg203 AS MEASURED BY A NEW COINCIDENCE METHOD
Authors: Taylor J. G. V.
Published: April 2011

Using a new coincidence method, the total internal conversion coefficient for the 279-kev transition following the β-decay of Hg203 has been measured with a standard deviation of about 1%. The method which employs a 4πβ–γ coincidence arrangement is based on the differential absorption of β-particles and conversion electrons in 4π geometry. For determining the absolute efficiencies of γ-ray spectrometers or ion-chambers, the method has the advantage of yielding directly the number of γ-ray quanta emitted per Hg203 disintegration without requiring any knowledge of the K:L:M conversion ratios. Likely sources of systematic error have been investigated and their effect has been shown to be smaller than the quoted standard deviation. The value obtained is α = 0.2262 ±.0019 or γ/β = 0.8155 ±.0015, in excellent agreement with the recent β-ray spectrometer measurements of Nijgh et al. This is of interest because a number of widely differing values of conversion coefficients for this transition have been reported. If the K/(L+M+N) conversion ratio of 2.60 ±.06 found by Nijgh et al. is combined with our total conversion coefficient, a value αK = 0.1633 ±.0017 is obtained.
THE CAPTURE OF PROTONS BY DEUTERONS
Authors: Griffiths G. M. , Larson E. A. , Robertson L. P.
Published: April 2011

The cross section and angular distribution of gamma rays for the reaction D(p,γ)He3 have been measured for proton energies from 275 kev to 1.75 Mev. For 275-kev protons the total cross section is 0.97 ± 0.11 microbarns and for 985-kev protons it is 3.5 ± 0.38 microbarns. The angular distribution has the form (sin2θ+b) where b is small. b is found to increase with decreasing proton energy, contrary to some previous results from this laboratory, and the energy dependence of b and of the cross section suggests that the sin2 θ part of the cross section is due to the capture of p-wave protons and the b part is due to s-wave proton capture.
STRUCTURE OF THE BAND SPECTRUM OF CuCl MOLECULE: II. ROTATIONAL STRUCTURE OF THE F–X BAND SYSTEM OF Cu65Cl35
Authors: Rao P. Ramakoteswara , Asundi R. K. , Brody J. K.
Published: April 2011

The F–X band system of Cu65Cl35 extending from 3700 to 4200 Å has been photographed in emission under high resolution. Rotational analysis of the (3,0), (2,0), (1,0), (0,0), (0,1), and (0,2) bands of the system has been made. The electronic transition involved is found to be 1Π–1Σ. The Λ-type doubling in the 1Π state is negligible. The principal molecular constants obtained are as follows (cm−1 units)[Formula: see text]
STRUCTURE OF THE BAND SPECTRUM OF CuCl MOLECULE: III. ROTATIONAL STRUCTURE OF THE B AND C SYSTEMS OF Cu65Cl35
Authors: Rao P. Ramakoteswara , Asundi R. K. , Brody J. K.
Published: April 2011

The B and C band systems of Cu65Cl35 lying in the region 4600–5200 Å have been photographed in emission under high resolution. Rotational analysis of the (1,0), (0,0), and (0,1) bands of each system has been made. The analysis shows that the B and C systems involve transitions 1Π(B1Π)–X1Σ and 1Σ (C1Σ)–X1Σ respectively. Due to the influence of the closeby C1Σ state, the B1Π state shows appreciable Λ-type doubling. It is found that the B1Π and C1Σ states provide an instance closely resembling the case of Van Vleck's "pure precession". The principal molecular constants obtained for the initial states of the B and C systems of Cu65Cl35 are as follows (cm−1 units):[Formula: see text]
THE PRESSURE PULSE PRODUCED BY A LARGE EXPLOSION IN THE ATMOSPHERE. PART II
Authors: Weston V. H.
Published: April 2011

The pressure pulse produced by a large explosion in the atmosphere is investigated. A realistic model for the vertical temperature is taken, with two temperature ducts and the large temperature gradient in the thermosphere. The first three dominant modes or "free waves" are computed for the low-frequency range. The contribution of these modes to the head of the pressure pulse produced by a large explosion is calculated for a particular range. It is shown that the "high-frequency" phenomena previously observed is a superposition of relatively low-frequency modes. An increase in the altitude of the source produces a corresponding decrease in relative intensity of the higher order modes, so that for an intense explosion at high altitudes, the low-frequency gravity wave mode is dominant.
GRAVITY AND ACOUSTICAL WAVES
Authors: Weston V. H.
Published: April 2011

The spectrum of the gravity and acoustical waves are discussed for two general types of models of the atmosphere. The main emphasis is placed upon the discrete set of modes which are important in the propagation of energy, long distances around the earth, from large explosions in the atmosphere.
RELATION OF COERCIVE FORCE TO STRUCTURAL PROPERTIES OF ELECTROPLATED FILMS
Authors: Lloyd J. C. , Smith R. S.
Published: April 2011

Coercive forces (He) of Fe–Ni films were observed to depend on thickness, Fe/Ni ratio, and preferred crystal orientation in accordance with predictions based on the Behringer–Smith model. Annealing induces marked crystal growth and orientation of [111] axis normal to the plane in the Ni-rich films (> 80% Ni), but only moderate growth in the Fe-rich (< 80% Ni) films. He for Ni-rich films increases markedly while He for iron-rich films decreases slightly due to annealing. Variations of the anisotropy field, Hk, due to applied stress, indicate that reduction of He for the Fe-rich films results from moderate crystal growth while the increase of He for the Ni-rich films is due to the preferred orientation.
SPECTROSCOPIC STUDIES OF HELIUM AND ARGON PLASMAS PRODUCED BY ELECTROMAGNETICALLY DRIVEN SHOCK WAVES
Authors: Barnard A. J. , Cormack G. D. , Simpkinson W. V.
Published: April 2011

An electromagnetic shock tube of new design was used to produce highly ionized helium and argon plasmas. The electron number density ne was determined spectroscopically from line broadening and line shifts, while the temperature kT was found from the relative intensities of HeI and HeII lines and of AII and AIII lines, respectively. The spectroscopic values were compared with predictions from shock theory. It was assumed that the shock-heated plasma reached thermal equilibrium before the first spectroscopic measurements were made (i.e. in a time of order 1 μsec after the onset of luminosity). For helium, with a shock speed of 4.8 cm/μsec and an initial particle density of 1.2 × 1016 cm−3, the spectroscopic temperature (3.7 ev) is in good agreement with the value expected from shock theory (3.8 ev). Line broadening indicates ne = 5 × 1017 cm−3, which is much higher than the shock theory value (1.5 × 1017 cm−3). For argon, with a shock speed of 1.9 cm/μsec and an initial particle density 2.1 × 1016 cm−3, the electron number densities (8, 6 × 1017 cm−3) agree within the experimental errors, but the spectroscopic temperature (2.5 ev) is substantially lower than the shock temperature (3.3 ev).