bluuebunny/crossref_metadata_2025 huggingface dataset:
THE REFLECTION OF WAVES IN A GENERALIZED EPSTEIN PROFILE
Authors: Burman R. , Gould R. N.
Published: April 2011

Epstein (1930) and Rawer (1939) studied the reflection of waves in a stratified medium by transforming the hypergeometric equation into the wave equation. A particular case of the Epstein profile is a symmetrical layer. Considerable attention has been given in the literature to this case as well as to symmetrical layers with certain other profiles of the refractive index. In the present paper a generalized Epstein profile is considered and the reflection and transmission coefficients are obtained. The special case in which the refractive index tends to the same constant value on either side of a layer is then discussed. The symmetrical Epstein profile is a special case of this layer which, in general, is asymmetrical. Particular attention is given to a layer differing only slightly from the symmetrical Epstein layer, a simple approximate formula for the reflection coefficient being derived.
VIBRATIONAL MOTIONS IN DIMETHYL ACETYLENE
Authors: Hougen Jon T.
Published: April 2011

A method is presented for giving a precise meaning to the concept of a "normal mode" in dimethylacetylene for the limiting case of almost free internal rotation. The normal modes so defined are shown to transform according to irreducible representations of the molecular symmetry group discussed in a previous paper. In addition, the effect on the energy levels of Coriolis interaction between the vibrational motion and both the overall rotation and the torsion is discussed for doubly degenerate and quadruply degenerate vibrational states. Selection rules for transitions between the various Coriolis components are presented, which are analogous to the "(+l), (−l) selection rules" for "ordinary" symmetric-top molecules. The effect of a small barrier to internal rotation is discussed briefly.
A LATTICE STATISTICS MODEL DERIVED FROM THE TWO-LAYER ADSORPTION PROBLEM
Authors: Betts D. D. , Hunter D. L.
Published: April 2011

A model is proposed for the physical adsorption of two layers of gas molecules at the sites of a regular lattice with lateral interaction between nearest-neighbor molecules. The model is more complicated than the two-dimensional Ising model. However, for a particular relation among the three energy parameters and at a particular value of the chemical potential the model simplifies considerably. For the simplified model and a square lattice of adsorption sites, high- and low-temperature series expansions for the specific heat have been obtained and the transition temperature estimated.
OSCILLATIONS IN MAGNETICALLY CONFINED COLD-CATHODE DISCHARGES AT VERY LOW PRESSURES
Authors: Redhead P. A.
Published: April 2011

Radio-frequency oscillations in a cold-cathode discharge with magnetron geometry have been observed in the pressure range 10−10 to 10−6 Torr. The discharge exhibited two distinct states. In state I, at low magnetic fields, no stable r-f. oscillations were observed and the low-frequency noise was large. In state II, at high magnetic fields, coherent oscillations of very narrow linewidth were observed in the frequency range 15 to 100 Mc/s. The frequency of oscillation was given approximately by f = (nVa)/(πra2B); (Va is the anode voltage, ra the anode radius, and B the magnetic field). Pressure had little effect on f other than a sudden change in mode number (n) from 1 to 2 at higher pressures. It is concluded that a dense rotating electronic space charge exists even at the lowest pressures examined. Calculations of the frequency of oscillation based on this model are in reasonable agreement with the measurements.
THE ADSORPTION AND REPLACEMENT OF HYDROGEN ON POLYCRYSTALLINE TUNGSTEN
Authors: Rlgby L. J.
Published: April 2011

Desorption spectra have been obtained which show that there are at least three β phases of hydrogen desorbed from a tungsten filament. The β2 phase was desorbed with second-order kinetics. The replacement of hydrogen by nitrogen and by carbon monoxide was observed, and simple replacement mechanisms are proposed for these processes and the replacement of carbon monoxide by nitrogen. When carbon was preadsorbed on the surface, the β1 phase of hydrogen and all the β phases of carbon monoxide and nitrogen were reduced, but the α phase of carbon monoxide was increased. A concept of identical and nonidentical sites is introduced to explain these results.
MEASUREMENT OF THE YIELDS OF 135I AND 140Ba IN THE FISSION OF 233U, 235U, 239Pu, AND 241Pu
Authors: Okazaki A. , Walker W. H.
Published: April 2011

Fission yields of 135I and 140Ba have been measured relative to the yields from 235U for samples of different fissile materials irradiated in the NRU reactor in a flux of 2.7 × 1014 neutrons/cm2 sec for 24 hours. The relative 135I contents of the samples were determined from the reactivity effect of the daughter 135Xe in the Chalk River Pool Test Reactor using a pile oscillator. The relative concentrations of 140Ba were determined by gamma-ray counting of the daughter 140La. The fractional yields, normalized to 0.0625 for both fission products in 235U fission, are:[Formula: see text]In the fission of 233U and 239Pu the cumulative yields to 135I and 140Ba are approximately 20% and 7% less than the mass-spectrometrically-measured cumulative yields to 135Cs and 140Ce respectively. The differences are attributed to direct formation of 135Xe and 140La.
RADIO STAR SCINTILLATION DURING THE JULY 20, 1963, ECLIPSE
Authors: Allen R. S. , Klobuchar J. A. , Kidd W. C. , Whitney H. E.
Published: April 2011

Amplitude scintillations of the radio energy from the galactic radio source Cassiopeia A were examined for the total solar eclipse of July 20, 1963, using the 150-foot parabolic antenna at the AFCRL Sagamore Hill Radio Observatory, Hamilton, Massachusetts. The extent of eclipsing varied along the ionospheric ray path from 100% at about 100 km to about 80% near 500 km. Chart recordings of the amplitude variations of the Cassiopeia A signal were made at frequencies of 29.8, 63, 113, and 228 Mc/s. The extent of variation in amplitude and rate of scintillation was comparable to that on control days. Examination of the frequency dependence showed that the scale size of the irregularities did not change significantly during the period of the eclipse. No effects in the scintillation records could be related uniquely to the reduction of ionizing illumination and subsequent cooling of the medium.
SATELLITE TRANSMISSION MEASUREMENTS OF IONOSPHERIC ELECTRON CONTENT AT A TIME OF LOW SOLAR ACTIVITY
Authors: Lyon G. F.
Published: April 2011

The results of observations of the 54-Mc/s signal from Transit IVA (1961 Omicron 1) during a 12-month period are presented. Total columnar electron content measurements are made by the differential Faraday rotation method. It is shown that the electron content is inversely dependent upon the magnetic-activity index during the summer months but not during the winter. The presence of horizontal gradients in content is sometimes indicated. It is also found that the variation of electron content with solar zenith angle indicates an ionosphere approximating an ideal Chapman layer.
OPTICAL ABSORPTION EDGE BROADENING OF EVAPORATED GERMANIUM FILMS
Authors: Glass A. M.
Published: April 2011

The absorption spectra of evaporated films of germanium, about 5 microns thick, are examined at room temperature and at 90 °K in the spectral range 0.5 to 1.0 eV. An absorption edge, considerably broader than the single-crystal edge and with no line structure, is seen in all cases. The broadening is studied as a function of substrate temperature during the film deposition, evaporation rate, and annealing time, and is interpreted in terms of the internal strains in the evaporated films.It is found that information on the quality of an evaporated film may be obtained from the study of the absorption spectrum.
A SIMPLE METHOD FOR DETERMINING THE LOCAL TIME OF GEOMAGNETIC MIDNIGHT
Authors: Montbriand L. E.
Published: April 2011

A discussion on geomagnetic time is given together with a new method of calculating the local time of geomagnetic midnight quickly and easily. Although this method is new, the ideas behind it are merely a simplification of a method set forth in a paper by A. G. McNish.
EXPERIMENTAL SENSITIVITY STUDY OF A 9-GHz ELECTRON PARAMAGNETIC RESONANCE SPECTROMETER
Authors: Buckmaster H. A. , Dering J. C.
Published: April 2011

The sensitivity of a 9-GHz magnetic field modulation, homodyne, electron paramagnetic resonance (EPR) spectrometer has been calculated as a function of the modulation frequency in the range 10 to 104 Hz from the measured frequency dependence of the parameters describing a selected matched pair of 1N23WE silicon point-contact crystal mixers. The calculated sensitivity was verified to within 3 dB by direct measurement of the signal-to-noise ratio of samples of a free radical (DPPH) containing a known number of unpaired spins in an EPR spectrometer employing the same crystal mixers. Data are also presented to show that the use of modulation frequencies in excess of 0.2 MHz does not result in improved sensitivity if modern crystal mixers are employed.
A COVARIANCE (COHERENCY) MATRIX FOR BACKSCATTERED AND SPATIAL ELECTROMAGNETIC NOISE
Authors: Childers D. G.
Published: April 2011

The covariance (coherency) matrix for both a backscattered electromagnetic process and a spatial-noise process is formulated. The elements of the matrix are the covariance and cross-covariance functions between orthogonal components of the electric field vector at right angles to the direction of propagation.First a backscattered model is developed. The time-varying covariance function for each component of the electric field vector is determined. An approximation is made in order to obtain an expression for the power spectrum of each component of the process. The component covariance function and the component power spectrum are both functions of the probability density that a scatterer will be at range r and time t as well as the transmitted pulse shape. This implies that in order to minimize the component (or total) power, the transmitted signal pulse may not be wide band, but is affected by the probability distribution of the scatterers.Next a stochastic representation for a general polarized, nonisotropic noise process is formulated. The formulation accounts for the three-dimensional aspects of the noise field. The purpose of the formulation is to determine the covariance matrix of the noise.
EFFET DU CHAMP DE FRANGE D'UN PRISME-LENTILLE MAGNÉTIQUE SUR LA POSITION DE L'IMAGE
Authors: Baril Marcel , Kerwin Larkin
Published: April 2011

Using measured values of the fringing-field intensity of a magnetic prism lens at a large number of points, divergent positive rays issuing from a point source may be traced by numerical calculation through the fringing field to a region within the homogeneous field of the prism. The traced rays enable a virtual source to be calculated, which then locates a virtual image by the Herzog method. The real image is found by symmetry. The method produces a theoretical image position closer to the experimentally determined position than other methods.
ELECTRICAL CONDUCTIVITY OF INERT GASES – SEED COMBINATION IN SHOCK TUBES: II. REFLECTED SHOCK MEASUREMENTS IN ARGON
Authors: Lau J. , Mills E.
Published: April 2011

The electrical conductivity of argon behind reflected shock waves in a shock tube was measured and compared with theory. The effect of seeding the argon with cesium chloride smoke was studied. The shock tube and seeding apparatus used was described by Lau (1964), except for a section added ahead of the dump tank where a gate can slide to form the end plate where the incident shock is reflected.
ON THE KELVIN–HELMHOLTZ PROBLEM IN MAGNETOHYDRODYNAMICS WITH FINITE CONDUCTIVITY
Authors: Wentzell R. A.
Published: April 2011

A study has been made of the effect of large but finite conductivity upon Kelvin–Helmholtz-type instabilities in the presence of a horizontal magnetic field. For finite conductivity, the selected Kelvin–Helmholtz-type problem which is stable at infinite conductivity is stable no matter how large the magnetic field. These instabilities grow aperiodically at a rate proportional to (resistivity)[Formula: see text].
ONE-PARTICLE ENERGY SPECTRUM OF AN ELECTRON SYSTEM IN A PERIODIC FIELD
Authors: Matsudaira Noboru
Published: April 2011

The energy spectrum of an electron in the vicinity of the Fermi surface of an electron system in a periodic field is determined approximately by applying the generalized self-consistent field method of Cohen. The main approximation involved may be regarded as an extension of the random phase approximation usually applied to the interelectronic interaction of an electron gas, to the case including a periodic field. The effect of the periodic field is treated by a secondorder perturbation.The result is expressed as[Formula: see text]The correction terms are roughly estimated numerically and are shown to be small for a simple model of a metal, metallic hydrogen. A brief discussion of the extension of the approximation is given.
THE INITIAL CREEP OF COLUMNAR-GRAINED ICE: PART I. OBSERVED BEHAVIOR
Authors: Gold L. W.
Published: April 2011

Previously undeformed columnar-grained ice exhibits a period of increasing or constant creep rate during the transient creep stage when loaded in simple compression perpendicular to the long axis of the columns. It is shown that this behavior is associated with the formation of small-angle boundaries and internal cracks. Creep strain beyond 0.25% for first load tends to a power-law dependence on time. On reload, specimens exhibit a normal transient creep behavior and have, initially, a lower resistance to deformation than for first load. With deformation, this resistance increases so that the reload creep curves cross the first load curves at about 0.2% creep. For reload, creep strain less than about 0.025% and greater than about 0.2% appears to have a power-law dependence on time with exponent about equal to that for first load.
A COMPOSITE NUCLEAR-LEVEL DENSITY FORMULA WITH SHELL CORRECTIONS
Authors: Gilbert A. , Cameron A. G. W.
Published: April 2011

At low excitation energies a "constant nuclear temperature" representation of nuclear-level densities is used, and at high excitation energies the regular Fermi gas formula is adopted. A method is developed for determining the parameters of the Fermi gas formula by using both the pairing and the shell-correction energies found by Cameron and Elkin for their semiempirical atomic mass formula in its exponential form. This procedure determines level densities at neutron-binding-energy excitations subject to an average factor error of 1.8. Methods are also developed for determining the parameters for the lower-energy formula in such a way that it best fits the lower-energy levels and joins smoothly to the Fermi gas formula. Correlations of the resulting parameters with shell and pairing effects are found. A composite prescription is given for calculating level densities in nuclei for which no experimental information is known. Tables give level density parameters for a wide variety of nuclei for which some experimental information is known. Some of the derivations of the Fermi gas formula in the literature were found to be slightly incorrect, so new derivations are presented in Appendixes.
A STUDY OF SOLAR EVOLUTION
Authors: Ezer D. , Cameron A. G. W.
Published: April 2011

Evolutionary sequences of solar models have been calculated using the Henyey method of model construction. These sequences were started at the threshold of stability, at which the released gravitational potential energy of the sun is just sufficient to supply the thermal, dissociation, and ionization energies of the model. It was found that the present solar characteristics were closely reproduced when a mixing length equal to two pressure scale heights was used in the convection theory, and when a solar initial helium abundance, based on solar cosmic-ray measurements, was chosen. The sun was again found to have a high luminosity during its contraction phase and to approach the main sequence in only a few million years. Tables of selected characteristics of some of the models are presented.
SCATTERING PHENOMENA IN DOUBLE-DIRECTION FOCUSING ELECTROMAGNETIC MASS SEPARATORS
Authors: Menat M. , Frieder G.
Published: April 2011

A series of experiments has shown that both elastic scattering and charge-exchange scattering of a directed ion beam by residual gas are dominant factors causing contamination in electromagnetic mass separators. These phenomena are treated numerically for various double-direction focusing machines. The method is based on geometrical considerations and on an appropriate and reliable interaction potential between the ions and the residual gas molecules. Significant expressions for the fractional contaminations as caused by these scattering phenomena are derived. The values depend on such factors as the residual gas molecule concentration, the fractional mass difference, the collector hole area, the magnet radius, a configuration factor, and some constants which appear in the expressions for the differential cross sections. By performing the various integrations in a different sequence, general expressions for the transmission from source to collector are obtained.
SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: IV. ENERGY TRANSFER IN RUBIDIUM–RUBIDIUM COLLISIONS
Authors: Rae A. G. A. , Krause L.
Published: April 2011

Sensitized fluorescence in rubidium vapor has been investigated in order to determine total cross sections for collisions of the second kind between rubidium atoms, leading to the transfer of excitation between the 5 2P1/2 and 5 2P3/2 resonance levels. The experiments were carried out at vapor pressures below 10−5 mm Hg, where there is virtually no imprisonment of resonance radiation. The exceedingly low fluorescent intensities were registered in an automatically programmed sequence of measurements, using photon counting techniques. The cross sections Q1(5 2P1/2 → 52P3/2) and Q2(5 2P1/2 ← 5 2P3/2) equal 53 Å2 and 68 Å2 respectively at 87 °C and 60 Å2 and 72 Å2 respectively at 107 °C. At both temperatures the ratios Q1/Q2 are in agreement with the values predicted by the principle of detailed balancing.
ON THE LINEAR DIELECTRIC PROPERTIES OF FINITE IONIC CRYSTALS
Authors: Grindlay J.
Published: April 2011

The basic equations for determining the linear dielectric constants of a finite ionic crystal with arbitrary basis are derived and shown to be equivalent to those obtained by Born and Huang for an infinite crystal. The derivation is based on the assumption that the relaxation of the interionic spacing at the surface of the crystal merely extends over a few layers of ions. The approach used in these calculations is extended to the description of certain long-wavelength oscillations with shape-dependent frequencies.
THE HELIUM CONTENT OF THE GALAXY
Authors: Truran J. W. , Hansen C. J. , Cameron A. G. W.
Published: April 2011

It is usually assumed in modern theories of nucleosynthesis that the initial composition of the galaxy was pure hydrogen. The large solar and stellar content of helium has appeared to present a difficulty for such an assumption. This paper examines the problem. Numerical studies are made of the time changes in the compositions of stars and the interstellar medium as a result of stellar evolution. It is concluded that the large helium content of the sun and recently formed stars can be produced only as a result of the evolution of stars of approximately solar mass. Hence the initial hydrogen hypothesis requires a large age for the galaxy ([Formula: see text] years). The content of long-lived radioactivities in the interstellar medium is also followed as a function of time. It is found that the ratios of radioactivities are very insensitive functions of time and are approximately those observed in the solar system when the helium content is satisfactory. However, it is also concluded that these ratios give little useful information about cosmochronology.
RADIATION FROM A PHASED LINE SOURCE IN A MAGNETOIONIC MEDIUM
Authors: Tuan H. S. , Seshadri S. R.
Published: April 2011

The radiation characteristics of a phased line source of electric current immersed in a magnetoionic medium are analyzed. The line source is assumed to be parallel to the direction of the external magnetostatic field and the phase constant for the current distribution is assumed to be given by k0/β, where k0 is the propagation constant of free space and β is a dimensionless phase parameter. In general, it is found that two modes are excited. The frequency ranges of propagation of these so-called ordinary and extraordinary modes are examined by means of a construction in the Ω2–R2 parameter space for the case [Formula: see text], where Ω = ω/ωp, R = ωc/ωp, and ω, ωp and ωc are the source, the electron plasma, and the gyromagnetic frequency respectively. The dispersion relations and the frequency spectrum are evaluated. It is found that β = 1 is a special case for which only one mode is excited.
A TEMPERATURE CURVE FOR THE UPPER ATMOSPHERE FROM 80 TO 160 KM BASED ON 3 914 Å N2+ ROTATIONAL TEMPERATURES IN AURORA
Authors: Brandy J. H.
Published: April 2011

Rotational temperatures derived from the 3 914 Å N2+ band in aurora along with simultaneous height measurements have been obtained in 1964 and 1965 for 75 points. The heights range from 82.5 km to 161.5 km and, from the average curve plotted, the gradient above about 95 km is 4.9°/km. Above that height the plot appears to be linear. Large differences in temperature from the average are thought to be considerably in excess of the maximum error expected, and may indicate variations in temperature in this zone for any given height.
ROTATIONAL SPECTRA OF TIF BY THE MOLECULAR BEAM ELECTRIC RESONANCE METHOD
Authors: Ritchie R. K. , Lew H.
Published: April 2011

Measurement of the J = 1 ← J = 0 transitions in TIF by the molecular beam electric resonance method has resulted in the following values for the rotational constants (Mc/sec):[Formula: see text]The internuclear distance for both isotopic species calculated directly from Be = h/8π2μre2 is re = 2.08442 ± 0.00009 Å. The mass ratio of the thallium isotopes is M203/M205 =0.990240 ± 0.000020
SYSTEMATICS OF FISSION BASED ON THE EXPONENTIAL MASS FORMULA
Authors: Cameron A. G. W.
Published: April 2011

A simple function of the fissionability parameter Z2/A is found, which enables fission thresholds to be calculated relative to the exponential mass formula reference surface (with shell and pairing corrections omitted). From these thresholds, systematics of spontaneous fission rates and of the ratios of neutron to fission widths are developed. A discussion is given of multiple neutron capture experiments in the light of these fission characteristics.
ABSORPTION SPECTRA OF MnF2, KMnF3, RbMnF3, AND CsMnF3
Authors: Stevenson Richard
Published: April 2011

Absorption spectra in the 3 000–4 000 Å region are presented for MnF2, KMnF3, RbMnF3, and CsMnF3 at room temperature, liquid-air temperature, and liquid-helium temperature. The spectra are similar at room temperature, but at low temperatures some differences appear. The 4.2 °K spectra of KMnF3 and CsMnF3 show evidence of splittings due to exchange-coupled ion pairs, and an estimate is made of the exchange-coupling constant for the excited states. The spectrum of KMnF3 shows two lines associated with a 4Γ3 level, which may be satellites caused by the magnetic phase transition. The spectra were examined in external magnetic fields up to 100 000 Oe, and no splitting or shiftings of the lines were observed. Crystal field parameters were calculated by fitting the room-temperature spectra.
THE EFFECT OF PRESSURE ON THE FERROMAGNETIC PHASE TRANSITION OF EuO
Authors: Stevenson Richard , Robinson M. C.
Published: April 2011

The compressions of EuO up to 10 000 atm have been measured at 296 °K, 82 °K, and 4.2 °K. The shift in temperature of the ferromagnetic phase transition has been measured as a function of pressure by measuring the mutual inductance of a coil containing the solid. The transition occurs at about 72 °K at 10 000 atm, which is about 5 °K higher than the transition at atmospheric pressure. The results tend to substantiate the molecular field model for EuO proposed by McGuire and Shafer. An estimate is made of the variation of the exchange interaction parameter with lattice parameter, ΔJ1/Δa = −0.62 °K/Å, where J1 refers to interactions between nearest magnetic neighbors.
HELMHOLTZ INSTABILITY OF A VISCOUS COMPRESSIBLE PLASMA
Authors: Bhutani O. P. , Sundaram A. K.
Published: April 2011

An attempt has been made to discuss the Helmholtz instability of a viscous compressible plasma considered to be a perfect electrical conductor. Initially, the plasma is assumed to be in contact with a uniform magnetic field along a plane boundary that is parallel to the field and is assumed to flow with uniform velocity V0 perpendicular to the field. By using the normal mode technique, the amplitudes of the perturbed quantities are obtained. The conditions for the validity of the principle of exchange of stability and overstability are obtained also. Finally, the growth-rate curves for different values of the viscosity parameter λ′ have been drawn and it has been found that the effect of viscosity adds to the stability of the system.
A PRECISE MEASUREMENT OF THE RANGE OF 100-MEV PROTONS IN ALUMINIUM
Authors: Portner P. M. , Moore R. B.
Published: April 2011

The range of 100-MeV protons in aluminium has been determined using the external beam of the McGill synchrocyclotron. The energy and range were determined for a finely collimated pencil beam with an energy spread of 0.12 MeV. Beam energy was measured by the floating-wire technique. Two range determinations yielded values of 9 840 ± 9 mg/cm2 at 99.88 ± 0.08 MeV and 9 768 ± 10 mg/cm2 at 99.58 ± 0.08 MeV. Range straggling was found to be in agreement with theory. The mean excitation potential in aluminium has been estimated from these results to be 156 ± 2 eV.
A NEW METHOD FOR FINDING HETEROGENEOUS ENERGY DISTRIBUTIONS FROM PHYSICAL ADSORPTION ISOTHERMS
Authors: Hobson J. P.
Published: April 2011

A model is described which assumes that a heterogeneous surface has a distribution of adsorption energies ƒ(E) for physical adsorption. A new solution is presented giving ƒ(E) for a number of step-type local isotherms, which are chosen to represent varying degrees of adsorbate–adsorbate interaction. The solution permits ƒ(E) to be obtained quite simply from isotherm data at one temperature. This solution for ƒ(E) may then be used to calculate isotherms at other temperatures. The latter isotherms represent predictions of the model and may be compared with experimental data.
MICROWAVE SCATTERING MEASUREMENTS IN THE RAYLEIGH REGION USING A FOCUSED-BEAM SYSTEM
Authors: Carswell Allan I.
Published: April 2011

This paper describes experimental studies on the scattering of microwaves from bodies whose sizes are much smaller than one wavelength. A focused-beam microwave system operating at a frequency of 8.68 Gc/sec is employed to measure backscattering cross sections as small as 5 × 10−4λ2. An effort is made to investigate the dependence of the radar cross section of small spheres and flat-ended cylinders on such variables as the volume of the scatterer, the length-to-width ratio, and the polarization of the incident wave. Measurements with systems containing more than one small scatterer are also described.
GAMMA TRANSITIONS BETWEEN EVEN-PARITY STATES IN 16O
Authors: Fujii S. , Rose M. E.
Published: April 2011

The large transition rates in the rotational band based on the 0+ state at 6.05 MeV in 16O are studied using Eisenberg, Spicer, and Rose's model for the even-parity states. The transition rates from low-lying 4+ states to low-lying 2+ states and from these 2+ states to the first excited 0+ state are calculated. The calculated values are much smaller than the experimental ones.
GEOMAGNETIC MICROPULSATION RESULTS FROM BYRD STATION AND GREAT WHALE RIVER
Authors: Jacobs J. A. , Wright C. S.
Published: April 2011

Early reports from the near-conjugate stations at Great Whale River and Byrd Station were based on the scanty data available in early 1961 (Lokken et al., Martin et al. 1961). The increased volume of data seems now to justify another preliminary report, in which the chief emphasis is on the time-agreement of the abrupt commencements of the numerous examples of Birkeland's "Polar Elementary Storms". Passing reference only is made to the associations at Byrd between VLF hiss and other ionospheric phenomena that are being reported by Stanford University. In the auroral zones, the magnetic activity is usually so great, even during the IQSY, that magnetograms can be employed usefully to supplement the micropulsation records. Using selected nighttime occasions, when the change in H is so sudden that a reasonable accuracy in the timing of the micropulsations can be achieved, it is found that the time differences between the two conjugate stations average ± 1 minute, although there is clear evidence that the two stations are not conjugate at all times, as evidenced by the lack of similarity of records. It is confirmed that the more abrupt changes in the magnetic field are associated with high-frequency "riders" of the order of 1 c.p.s., and that these events are often seen with the same riders at the same time at our mid-latitude stations. The return currents that show up in these lower latitudes must be taken into consideration when the areas of conjugate station agreement are considered. The daytime regime of regular (Pc) variations did not lend itself to accurate time comparison, except for very long-period oscillations at the two stations, when the maximum excursions were so far apart in time that one could reasonably assume that the indicated phase differences on the records at the two stations were correct. On this assumption, the long-period oscillations are nearly coincident at the two stations. This may usually be true for the shorter-period oscillations also, but, in many cases, considerable phase differences do exist. These, however, may be due partly to differences in the electronic equipment.The general course of the geomagnetic diurnal variation at Byrd is shown, but these data may apply only to the two auroral conjugate stations and to periods of low solar activity.Up to the present time, only two cases of coincident satellite and ground station abrupt commencements have been observed. These were detected readily only by our mid-latitude stations, possibly because the two events occurred when these stations were on the side of the earth facing the solar wind. It is possible that nighttime coincidences will appear chiefly at the two auroral stations.
FINITE AND INFINITE H-PLANE BIFURCATION OF A WAVE GUIDE WITH ANISOTROPIC PLASMA MEDIUM
Authors: Lee S. W. , Lo Y. T. , Mittra R.
Published: April 2011

In this paper, the problem of H-plane bifurcation in a parallel-plate wave guide filled with homogeneous, anisotropic, incompressible plasma is considered. The static magnetic field is assumed to be along the edge of the septum. By using the Wiener–Hopf technique, the complete field solutions are obtained for both semi-infinite and finite bifurcations.
THE SECOND MAXIMUM OF COSMIC-RAY STAR FREQUENCY UNDER LEAD
Authors: Forbes V. M. , McPherson A. I.
Published: April 2011

The transmission of cosmic radiation at 3 392 meters through lead was studied over a range of thicknesses between 10 and 20 cm with intensities measured in terms of star frequency in photographic emulsions. A second maximum was observed between 16 and 17 cm of lead, the transmitted radiation being equal in intensity to the incident radiation.
THE GROWTH OF CORRUGATIONS ON ACCELERATED FLUID SHEETS
Authors: Curzon F. L.
Published: April 2011

The growth of waves or corrugations on sheets of infinitely conducting fluid accelerated by electromagnetic forces is studied. Two cases are considered: circular cylindrical sheets accelerated by constant axial currents and planar sheets accelerated by currents that are constant or increase linearly with time. Only corrugations that are parallel to the magnetic field lines are considered. For the cylindrical model the theory is valid only provided axial motion is very small. For the planar case initial corrugations of any amplitude can be considered, since it is not necessary to linearize the equations of motion in order to obtain solutions in a closed form. It is shown that the validity of the theory is limited by the axial motion of the fluid sheet and that, for sinusoidal corrugations of very small initial amplitude, the theory remains valid until this amplitude increases to λ/2π, where λ is the wavelength of the corrugation.
THE REFLECTION AND DUCTING OF ATMOSPHERIC ACOUSTIC–GRAVITY WAVES
Authors: Pitteway M. L. V. , Hines C. O.
Published: April 2011

A simple form is derived for the differential equations governing the propagation of acoustic–gravity waves in an atmosphere whose temperature and horizontal wind velocity vary in an arbitrary manner with height. The condition for wave reflection is discussed in some detail, and the W.K.B. approximate solutions are derived and examined. Analytic solutions are obtained for exponential and for linear variations of temperature with height, and group velocities for ducted modes are studied with these models.
SOLUTION OF THE PARTIAL-WAVE DISPERSION RELATIONS
Authors: Razavy M.
Published: April 2011

Different methods of solving partial-wave dispersion relations are presented, and special forms of these relations which can be reduced to the solution of the Fredholm integral equation have been examined in some detail. The analyticity of the resulting scattering amplitude in terms of the square of the coupling constant is studied, and the impossibility of generating the complete scattering amplitude from the lowest term of its expansion in powers of the coupling constant has been shown.
THE ELECTRON SPIN RESONANCE OF Fe+3 IN SINGLE CRYSTALS OF SPODUMENE
Authors: Manoogian A. , Holuj F. , Carswell J. W.
Published: April 2011

The electron spin resonance (ESR) spectrum of Fe+3 in spodumene, LiAl(SiO3)2, has been investigated at 24 kMc/sec. One set of five "allowed" transitions between the magnetic sublevels of the 6S5/2 ground state has been detected. The following values have been assigned to the parameters occurring in the spin Hamiltonian (eq. (1)) (bnm in gauss): gx = 2.0086 ± 50, gy = 2.0100 ± 50, gx ± 2.0046 ± 25, b20 = −1 430, b22 = −282, b40 = −20, b42 = 108, b44 = −182. Consideration of electric field gradients measured by methods of electric quadrupole resonance and of the orthorhombic parameters b20 and b22 did not lead to a unique assignment of the Fe+3 impurity to one of the two available cationic sites in spodumene.
AURORAL PHENOMENA IN AN INTEGRAL-INVARIANT COORDINATE SYSTEM
Authors: Waite C. W.
Published: April 2011

Isochasms of auroral phenomena, when plotted in geomagnetic dipole coordinates, are approximately circular and centered on the poles. However, a significant longitude dependence remains. The B, L and R, λ integral-invariant coordinate systems, originated by Mcllwain, have proved successful in ordering satellite measurements of the radiation belts. The spatial occurrence of aurora has been compared with isolines of L but the R, λ system appears better suited to such plots. The evidence for a close relationship between auroral absorption and electron precipitation from the radiation belts is reviewed, and in accordance with this relationship it is shown that the R, λ coordinate system provides a convenient longitude-independent representation of the northern auroral absorption zone.
INDUCED INFRARED ABSORPTION OF NITROGEN AND NITROGEN – FOREIGN GAS MIXTURES
Authors: Reddy S. Paddi , Cho C. W.
Published: April 2011

The pressure-induced fundamental vibration–rotation absorption band of nitrogen was studied in the pure gas and in nitrogen–argon, nitrogen–hydrogen, and nitrogen–helium mixtures at room temperature for pressures up to 1 500 atm. The shapes of the absorption profiles obtained in each case were discussed. The enhancement absorption profiles of nitrogen–argon mixtures exhibited the sharpening of the individual branches of the fundamental band with a small frequency shift, while those of nitrogen–hydrogen and nitrogen–helium mixtures indicated a splitting of the Q branch. Binary and ternary absorption coefficients were determined for pure nitrogen and nitrogen – foreign gas mixtures. The graph drawn with (1/ρa2) ∫α(ν)dν vs. ρa for pure nitrogen and those drawn with (1/ρaρb) (∫α(ν)dν)enhancement vs. ρb for mixtures were found to be straight lines. Except for nitrogen–helium mixtures all these straight lines had negative slopes, and this was interpreted as a partial cancelation of the induced moments due to ternary collisions. Applying the theory of Van Kranendonk and using the known molecular constants, the molecular quadrupole moment Q of nitrogen and its derivative Q′ with respect to the internuclear distance at its equilibrium position were determined. The values of Q and Q′ were obtained as 1.1ea02 and 0.97ea0 respectively; the value of Q is in good agreement with that determined by previous investigators.
LIQUID HELIUM AND THE PROPERTIES OF FINITE BOSE–EINSTEIN ASSEMBLIES
Authors: Goble D. F. , Trainor L. E. H.
Published: April 2011

In order to explain certain properties of thin helium films, Ziman has proposed an ideal gas model in which the bulk liquid is treated as a collection of independent, Bose–Einstein assemblies each a few hundred angstroms in extent. In this paper, an extensive numerical study is made of the thermodynamic properties of such finite assemblies. In particular, the specific heats of thin films have been calculated on the basis of the model and the results compared with the experimental data of Frederikse. It is found that the model predicts a shift of the specific-heat maxima to higher temperatures as the film thickness is decreased, rather than to lower temperatures as required by the observations on actual helium films. The nature of the Bose–Einstein condensation in finite assemblies is discussed in some detail and some general conclusions are drawn concerning Ziman's model.
TABLES OF DEBYE FUNCTIONS
Authors: Howard Roger , Grindlay J.
Published: April 2011

Tables and asymptotic limits of the Debye functions[Formula: see text]are presented for n = 0.5, 1.0, 1.5, 2.0, 2.5. This information may be used to facilitate the calculation of the negative moments of the phonon frequency distribution function from the heat capacity data of crystals.
ABSORPTIVE CORRECTIONS TO THE NUCLEON EXCHANGE TERM IN ELASTIC πN SCATTERING
Authors: Smrz Pavel , von Baeyer Hans C.
Published: April 2011

The absorption model of Gottfried and Jackson is justified in the case of backward elastic scattering. The model is then applied to the nucleon exchange term in π+p scattering at 4 and 8 BeV. It is found that the data can be fitted only if a phenomenological form factor is introduced.
DIRECTIONAL SOLIDIFICATION OF ALUMINIUM–COPPER ALLOYS IN A MAGNETIC FIELD
Authors: Youdelis W. V. , Dorward R. C.
Published: April 2011

The degree of normal segregation, occurring during directional (normal) freezing in a transverse magnetic field of 34 000 oersteds, has been determined for aluminium–copper alloys solidified for rates of [Formula: see text] to 4 inches per hour. For ingots in the composition range 0.5% < %Cu < 4.5%, solidified at rates exceeding [Formula: see text] inch per hour, the magnetic field increased normal segregation, corresponding to a maximum decrease in the effective distribution coefficient ke of approximately 13%. It is shown that the decrease in ke can occur only through a rise in the liquidus of the alloy system, which is in agreement with the theory developed to account for the inverse segregation results obtained for aluminium–copper ingots chill-cast in a magnetic field (previously reported). An increase in ke due to the field was found for 0.5% Cu ingots and also for the 4.5% Cu and 7% Cu ingots. The concentration dependence of ke is related to the concentration gradients and diffusion zone lengths, and is shown to be compatible with the thermodynamic constraints on the system undergoing the irreversible process of solidification in a magnetic field.
VALIDITY OF THE JARMAIN–SANDEMAN SERIES FOR CALCULATING POTENTIAL CURVES OF DIATOMIC MOLECULES
Authors: Davies R. H. , Vanderslice Joseph T.
Published: April 2011

The Jarmain–Sandeman series for the determination of potential curves for diatomic molecules is shown to be absolutely convergent for energies up to the dissociation limit. The rapidity of convergence is also tested, and it is concluded that the series should be reliable for most cases of interest.
THE RATIO OF THE DIRECT TO THE CUMULATIVE YIELD OF 135Xe IN THE THERMAL NEUTRON FISSION OF 233U, 235U, 239Pu, AND 241pu
Authors: Okazaki A. , Walker W. H. , Bigham C. B.
Published: April 2011

The ratio of the direct to cumulative yields of 135Xe produced in thermal neutron fission has been determined by measuring the growth and decay of this nuclide in irradiated 233U, 235U, 239Pu, and 241Pu. After a short irradiation in a low neutron flux, the amount of 135Xe increases and reaches a maximum at about 11 hours after the end of the irradiation. The direct yield of 135Xe modifies the time this maximum is reached. The ratio of the direct to cumulative yields was determined by measuring the time shift of the growth and decay curve. The amount of 135Xe was measured as a function of time after the end of irradiation by counting the 249-keV γ ray accompanying the β decay of 135Xe with a lithium-drifted germanium-diode spectrometer. The ratio of the direct to the cumulative yield was found to be 0.195 ± 0.016, 0.044 ± 0.017, 0.162 ± 0.025, and 0.070 ± 0.040 for 233U, 235U, 239Pu, and 241Pu fission respectively.
WAVE PROPAGATION IN MAGNETOPLASMAS
Authors: Sharma S. R.
Published: April 2011

Wave propagation in a fully ionized unbounded magnetoplasma is considered taking into account the momentum transfer and energy exchange due to collisions. Dispersion relations are examined for wave propagation along and perpendicular to the magnetic field. It is found that there is no additional damping due to temperature relaxation for pure transverse wave propagation. For longitudinal waves dispersion relations are presented which include damping due to temperature relaxation and momentum transfer due to collisions.
SPIN ASSIGNMENTS FOR THREE RESONANCES IN 191Ir
Authors: Bhat M. R.
Published: April 2011

Resonant scattering of neutrons by iridium has been studied with samples of three different thicknesses. The scattering cross section for the 5.36-eV, 30-eV, and 51.3-eV resonances of 191Ir was measured. These measurements combined with the published transmission data and the fact that the target nucleus has a spin of 3/2 give the spins of these resonances. The 5.36-eV resonance is found to have a spin of 2, while each of the other two resonances has a spin of 1.
A METHOD OF DETERMINING CROSS-CORRELATION COEFFICIENTS OF TIME-VARYING SIGNALS
Authors: Palmer F. H. , Lyon G. F.
Published: April 2011

Pulse-counting techniques allow the cross-correlation coefficient between two time-varying signals to be rapidly evaluated, if the two signals are first converted to pulse trains whose repetition frequencies are proportional to the respective amplitudes. Equipment using this technique is described. Estimates are given of the overall accuracy of the device for various types of input signal and for various signal durations. Provided the depth of modulation of the signals is over 50%, their cross-correlation coefficient may be determined to an accuracy of ± 0.05 for sample lengths of 2 minutes. The application of the system to the determination of cross-correlation coefficients of v.h.f. forward-scattered signals received on spaced antennae is also described.
DÉPLACEMENT ISOTOPIQUE RELATIF DES ISOTOPES 238, 235, ET 233 DE L'URANIUM ET MOMENTS QUADRUPOLAIRES INTRİNSÈQUES DES ISOTOPES 238 ET 236
Authors: Gagné Jean-Marie
Published: April 2011

not available
THE CORIOLIS ζ SUM RULES
Authors: Lepard D. W.
Published: April 2011

A review of the theory has shown that the Coriolis ζ sum rules, given previously in several papers, are not applicable to the degenerate symmetry species En−1 of the molecular point groups Dnd and S2n, n even. In this paper the correct ζ sum rules are derived and are included in a table giving the sum rules for all degenerate symmetry species of all symmetric-top point groups.
TIME-DEPENDENT CHARACTERISTICS OF THE HETEROGENEOUS NUCLEATION OF ICE
Authors: Vali Gabor , Stansbury E. J.
Published: April 2011

The dependence of heterogeneous nucleation of supercooled water drops on temperature and on the duration of supercooling has been studied. The rain-sized drops were placed on an oiled aluminium surface; thermoelectric refrigeration was used to provide constant cooling rates and to maintain constant temperatures. Once-distilled tap water and melted snow and hail were investigated. Only the first two of these showed definite time-dependent properties.The experimental results are inconsistent with the hypothesis that all drops have equal probability of nucleation (stochastic hypothesis), and also with the hypothesis that the freezing temperature of a drop is the characteristic temperature of one of the impurities contained in the drop ("singular" hypothesis). The results are interpreted in terms of a model in which the characteristics of a particular nucleating site determine a range of possible nucleation temperatures for that site, and within that range of less than 2 degrees the probability per second for a nucleation event increases rapidly with increasing supercooling.
ESR SPECTRA OF Fe+3 IN SINGLE CRYSTALS OF ANDALUSITE
Authors: Holuj F. , Thyer J. R. , Hedgecock N. E.
Published: April 2011

ESR spectra of Fe+3 in andalusite have been investigated at X- and K-band frequencies at room temperature. They have been interpreted on the assumption that Fe+3 occupies the two inequivalent Al+3 sites in andalusite. The spectra show large zero-field splitting. The constants of the conventional orthorhombic spin Hamiltonian which fit the spectra are as follows: for site I: b20 = 15.0 ± 0.1 kG, b22 = 5.0 ± 0.1 kG, and isotropic g = 2.001 ± 0.002; for site II: b20 = 20.1 ± 0.1 kG, b22 = 0.075 ± 0.010 kG, and isotropic g = 2.004 ± 0.0005. A study of the intensities of ESR signals due to site I follow a pattern predicted by theory. The implications of these results are considered briefly.
ABSORPTION SPECTRA OF HCCl AND DCCl
Authors: Merer A. J. , Travis D. N.
Published: April 2011

A long progression of absorption bands appearing in the region 5 500–8 200 Å has been observed in the flash photolysis of dibromochloromethane, HCClBr2. Observation of chlorine and deuterium isotope shifts, together with the results of the rotational analyses, have shown that the carrier of the bands is the chloromethylene radical, HCCl.The ground state of HCCl is a 1A′ state in which the molecule has an equilibrium angle of ~103°, a C—H bond length of 1.12 Å, and a C—Cl bond length of 1.69 Å. In the upper state, of character 1A″, unusual patterns of the vibrational and K-type rotational energy levels indicate that the molecule, although bent, has a low barrier to linearity and is easily "straightened" by vibration. The vibrational levels of the upper state may be fitted quite accurately, using a potential function for the bending vibration of the type suggested by Thorson and Nakagawa (1960); our calculations show that the equilibrium angle in the upper state is ~135° and that the top of the barrier lies 2 250 cm−1 above the lowest vibrational level.The large change of angle in the transition causes the appearance of subbands with ΔK = 0 and −2 in addition to those allowed by the strict type-C selection rules. The intensities of the forbidden subbands are well explained by the axis-switching mechanism suggested by Hougen and Watson (1965).