bluuebunny/crossref_metadata_2025 huggingface dataset:
THE ANGULAR DISTRIBUTION OF γ-RAYS FROM Mn54 ORIENTED IN ANTIFERROMAGNETIC CoCl2.6H2O
Authors: Daniels J. M. , Griffiths D. J.
Published: April 2011

The angular distribution of γ-rays from Mn54 nuclei, included as an impurity in antiferromagnetic CoCl2.6H2O, was measured at temperatures between 0.03 °K and 0.18 °K. Three γ-ray counters were placed, one each along the crystallographic a, b, and c axes, and the angular distribution was analyzed into a series of spherical harmonics. The aspheric component of the γ-ray distribution was found to be proportional to [Formula: see text], where θ and [Formula: see text], are polar co-ordinates; the polar axis is the crystallographic b axis, and the origin of [Formula: see text] is 46° from the a axis in the obtuse angle between the a and c axes. This result is discussed in terms of present knowledge of the antiferromagnetic ground state configuration of CoCl.6H2O and of present ideas of the mechanism of nuclear alignment in antiferromagnetic materials, but no satisfactory explanation is found.
NUCLEAR ORIENTATION OF Mn54 IN MnSiF6∙6H2O
Authors: Daniels J. M. , Griffiths D. J.
Published: April 2011

Mn54 was oriented in a single crystal of MiiSiF6∙6H2O, and the anisotropy of emission of γ-rays relative to the trigonal axis of the crystal was measured as a function of temperature in the range 0.06° K to 0.12° K. The anisotropy exhibited the expected I/T3 dependence in this temperature range. From these measurements, a value of −0.034 ± 0.005 cm−1 was deduced for the value of the constant D which occurs in the spin-Hamiltonian [Formula: see text].
CONDUCTIVITY OF ELECTRONS IN GASES WEAKLY IONIZED BY X RAYS
Authors: Carruthers J. A.
Published: April 2011

Results are reported for oxygen and air at 1–10 mm Hg pressure irradiated by 100-kvp X rays at about 4300 roentgens/hour. Measurement of both terms of the complex conductivity of the gas at 50 Mc/s by a bridge technique, with modulation of the X-ray source at 120 c/s, gives data on the collision frequency v, the electron density n, and the dependence of collision frequency on the electron energy u ev. The limit of sensitivity is about one electron per cc. For dry air the data agree well with recent drift tube results by Pack and Phelps represented by v(u) = 1.38 × 10−7N(air) u sec−1, where N(air) is the air density in molecules/cc. For O2 fair agreement with v(u) = 7 × 10−8N(O2)u sec−1 is observed, but the power of u may be greater than unity. The electron densities are consistent with three-body attachment of the electrons to neutral O2 molecule with the coefficient 2.8 × 10−30 cm6/sec reported by Chanin et al. for thermal electrons.
FRANCK–CONDON FACTORS AND r-CENTROIDS TO HIGH VIBRATIONAL QUANTUM NUMBERS FOR THREE BAND SYSTEMS OF CO+ AND ABSOLUTE BAND STRENGTHS FOR THE COMET-TAIL SYSTEM
Authors: Nicholls R. W.
Published: April 2011

Franck–Condon factor and r-centroid arrays computed to high vibrational quantum numbers for Morse potentials are displayed for the CO+ comet-tail (A2Πi–X2Σ+), first negative (B2Σ+–X2Σ+), and Baldet–Johnson (B2Σ+–A2Πi) band systems. Estimates of band strengths are made for CO+ comet-tail bands.
CYCLOTRON RESONANCE IN ANTIMONY AT 35 Gc/sec AND 70 Gc/sec
Authors: Datars W. R.
Published: April 2011

Single-crystal antimony has been investigated by means of cyclotron resonance using the Azbel'–Kaner geometry and microwave frequencies of approximately 35 Gc/sec and 70 Gc/sec. Electropolished or cleaved crystal surfaces that contained principal crystal planes were used in the study. The results have been analyzed and the mass tensor components of the Shoenberg model of the electron Fermi surface were found to be m1′ = 0.043, m2′ = 1.46, m3′ = 0.070, tilt angle = 36°, which are in close agreement with values measured by Shoenberg using the de Haas – van Alphen effect. Signals, which were interpreted to be cyclotron resonance at limiting points of the electron Fermi surface, suggested nonellipsoidal features of the electron Fermi surface and were interpreted using Cohen's nonellipsoidal model of the bismuth-type structure with rotation symmetry. Evidence of the presence of holes consisted of two Azbel'–Kaner resonances for each magnetic-field direction and suggested the existence of a nonellipsoidal energy surface in the valence band of antimony. The hole-cyclotron mass values that were observed are reported.
THERMAL ORIGIN OF NONOHMIC MAGNETORESISTANCE EFFECTS IN SEMIMETALS
Authors: Eastman P. C. , Datars W. R.
Published: April 2011

The magnetoresistance in antimony, bismuth, and arsenic samples immersed in liquid helium has been investigated. With a helium bath at 4.2° K, the nonohmic resistance, observed when the sample power dissipation exceeded 0.5 watt/cm2, was correlated with a sample temperature that was above the bath temperature. The temperature rise is explained on the basis of film-boiling at the solid-liquid interface. The elimination of this thermal effect is necessary for the observation of the nonlinear effect observed by Esaki in bismuth.
SPECTRUM AND STRUCTURE OF THE FREE HNCN RADICAL
Authors: Herzberg G. , Warsop P. A.
Published: April 2011

A widely spaced perpendicular band at 3440 Å observed in the flash photolysis of diazomethane is ascribed to the free HNCN radical. The study of the fine structure of this band for HNCN, DNCN, and HNC13N has yielded information about the geometrical structure of the molecule in both the upper and lower (ground) state. For the lower state[Formula: see text]The N—C—N group is very nearly linear, but the exact position of the C atom on this line could not be determined. The electronic transition is of the type 2A′–2A″, the transition moment being perpendicular to the plane of the molecule.
THE MODE THEORY OF VLF RADIO PROPAGATION FOR A SPHERICAL EARTH AND A CONCENTRIC ANISOTROPIC IONOSPHERE
Authors: Wait James R.
Published: April 2011

The theory of the propagation of electromagnetic waves in the space between a spherical conducting earth and a concentric ionospheric reflecting layer is treated. The problem is idealized to the extent that, at the boundaries of this spherical wave guide, the tangential field components are related in a prescribed way. In the case of the ground, the relation involves a scalar surface impedance while, for the ionosphere, it is necessary to employ a reflection coefficient or surface impedance in the form of a matrix. On this basis a solution is sought for the total field produced by a vertical electric dipole. Explicit results are obtained under the assumption of azimuthal symmetry. By applying the Watson transformation a representation in terms of guided waves is obtained. This form of the solution was used previously by the author to obtain specific results.
EXCITATION CURVES FOR THE REACTIONS Al27(n, α)Na24 AND Mg24(n, p)Na24
Authors: Butler J. P. , Santry D. C.
Published: April 2011

Excitation curves for the reactions Al27(n, α)Na24 and Mg24(n, p)Na24 have been measured by the activation method from near threshold energies to 20.3 Mev. The measurements are relative to the known cross section for the reaction S32(n, p)P32. Monoenergetic neutrons were obtained from the D(d, n)He3, T(d, n)He4, and the T(p, n)He3 reactions employing a Tandem Van de Graaff accelerator or 125-kev accelerator. Cross sections for both reactions rise above the minimum detectable value of 0.02 mb near 5 Mev and reach maximum values of 126 mb for the Al(n, α)Na24 reaction and 205 mb for the Mg24(n, p)Na24 reaction at 13.5 Mev. Above this energy both cross sections decrease. From the excitation curves effective cross-section values for a fission-neutron spectrum have been calculated as 0.61 ± 0.03 mb for the (n, α) reaction and 1.34 ± 0.07 mb for the (n, p) reaction.
THE LOSS OF FREE ELECTRONS IN IRRADIATED AIR
Authors: Young B. G. , Johnson A. W. , Carruthers J. A.
Published: April 2011

The loss of free electrons in air, nitrogen, and oxygen is studied as a function of pressure by continuously irradiating the gases with high-energy electrons and measuring the equilibrium electron densities with a microwave probe. At low pressures (1–10 mm Hg) electrons are lost by free diffusion to the chamber walls before cooling. At intermediate pressures (10–100 mm Hg) electrons cool rapidly without loss to thermal energy and then disappear by three-body attachment in air and oxygen, and by electron–ion recombination in nitrogen. At high pressures (100–1000 mm Hg) the electron density increases with irradiation time and the controlling loss mechanism is uncertain.
NUCLEAR CHARGE DISPERSION IN THE HIGH-ENERGY FISSION OF URANIUM
Authors: Davies J. H. , Yaffe L.
Published: April 2011

The independent formation cross sections of Cs130, Cs132, Cs134, Cs136, Cs138, Rb86, Nb95m, Nb96, and Nb97 produced in the fission of natural uranium by protons have been measured radiochemically at incident proton energies ranging from 10 Mev to 85 Mev. The excitation functions correlate well with those obtained by Friedlander, Friedman, Gordon, and Yaffe (1963). Charge dispersion curves were constructed at 20, 36, 50, 65, and 80 Mev. The curves broaden with increasing proton energy and the most probable charge approaches the line of β-stability. An explanation for both of these effects is given in terms of spallation–fission competition.
RADIATION FROM A CURRENT FILAMENT CLAD BY AN ANISOTROPIC PLASMA SHEATH
Authors: Ohba Yujiro
Published: April 2011

The radiation field from a plasma-clad filament carrying a current I0 exp (−jkzz + jωt) is calculated. The plasma, which is finite in thickness, is magnetized in the direction parallel to the current filament. The field outside the plasma sheath is expressed by a combination of TE and TM modes, and in general the field is elliptically polarized. The conditions for circular and linear polarization in the far field are related to the thickness of the plasma sheath and the wave constants of the plasma.
CRITERIA FOR THE ASSOCIATION OF SOLAR FLARES WITH GEOMAGNETIC DISTURBANCES
Authors: Jenkins R. W. , Paghis Irvine
Published: April 2011

The statistical relation between solar flares of importance [Formula: see text] and the onset of geomagnetic disturbances was studied for 1949–61. Disturbances were defined as an increase in ap[Formula: see text], occurring within 12 hours or less, and these disturbances include both gradual and sudden commencement events. Associated radio noise bursts at frequencies below 300 Mc were used to select 240 major-burst flares, and the effects of flare importance, time of solar epoch, and associated polar-cap-absorption (PCA) events were considered in turn. A detailed examination was made of the effect of flare heliographic location. There is a strong positive correlation between the occurrence of major-burst flares and geomagnetic disturbances 1 to 3 days afterwards. The degree of correlation is approximately doubled when the major-burst flare is associated with a PCA event. The most probable time delay between flares and disturbances is 1.5 to 2.0 days, and this timing is relatively constant over a wide range of conditions.The dominance of northern storm-flares (Bell 1961) was confirmed for 1949–61. Detailed analysis shows that the effect is strongest for heliographic latitudes above 15 °N. In addition to this effect, there was a consistent western bias of the storm-flares in both the northern and southern hemispheres, for flares associated with either gradual or sudden commencement (SC) events, with maximum concentration occurring at 10 °W. to 15 °W. Major-burst flares associated with PCA events also show this western bias; the data suggest that there is a systematic increase in east–west asymmetry in going from major-burst storm-flares to major-burst PCA flares to PCA flares accompanied by ground-level cosmic-ray increases. The corresponding longitudes of maximum concentration of the associated flares are about 10 °– 15 °W., 45 °W., and 75 °W.
THE ISOTHERMAL PELTIER COEFFICIENT AND PHONON-DRAG IN COPPER
Authors: Henry W. G.
Published: April 2011

An apparatus is described for making direct measurements of small Peltier coefficients of the order of 1 mv and less below room temperature. The Kelvin relationship between the thermopower and the isothermal Peltier coefficient is shown to hold for the copper–lead couple from 77.4° to 298° K.
CONCENTRATION OF NATURAL AND ARTIFICIAL AIRBORNE ACTIVITIES NEAR GROUND LEVEL AT WINNIPEG
Authors: Connor R. D.
Published: April 2011

Concentrations of radon, thoron, and particulate fallout have been evaluated on a day-to-day basis from December 1958 to May 1962. The results are given in detail for the period linking the International Geophysical Year (I.G.Y.) to the program of the Radiation Protection Division (R.P.D.) of the Canadian Department of National Health and Welfare, and for the period subsequent to the Russian tests in the fall of 1961. The efficiency of the filter type 934-AH for the collection of aerosols carrying the active deposits of radium and thorium has been determined as 98.2 ± 0.8%. The magnitude and extent of the corrections applied to the data are discussed in detail and the published results for the fallout concentration at Winnipeg during the I.G.Y. and R.P.D. programs are compared with the present data. The decay of fresh fallout has been followed for periods of up to two months and a correlation between the date of explosion and the occurrence of a peak in the fallout concentration is indicated.
THE ABSORPTION SPECTRUM OF 35Cl2 FROM 4780 TO 6000 Å
Authors: Douglas A. E. , Møller Chr. Kn. , Stoicheff B. P.
Published: April 2011

The discrete absorption bands of gaseous chlorine which lie between 6000 Å and the dissociation limit, near 4780 Å, have been photographed at high resolution with a 10-meter concave-grating spectrograph. This complex spectrum has been simplified by the use of the separated isotopic species 35Cl2 and by cooling the cell. An analysis of all the strong bands has been achieved. The principal constants of the ground state are Be = 0.24407, α = 0.00153, ωe = 559.71, ωexe = 2.70, [Formula: see text], and re = 1.9878 Å.
STOPPING CROSS SECTIONS IN CARBON FOR LOW-ENERGY ATOMS WITH
Authors: Ormrod J. H. , Duckworth H. E.
Published: April 2011

The electronic stopping cross sections in carbon for atomic projectiles with [Formula: see text] have been determined in the energy interval from 10 to 140 kev. In doing so a Monte Carlo calculation was used to subtract from each experimentally observed cross section the contribution which arises from nuclear scattering. The trend of the results thus obtained agrees well with theory. In addition, however, a periodic dependence of Sε on the atomic number of the projectile is observed.
ACCELERATION AND DECELERATION OF PLASMAS IN ELECTROMAGNETIC SHOCK-TUBES
Authors: Cormack G. D.
Published: April 2011

The applicability of snowplough theory for the description of the motion of plasmas in electromagnetic shock-tubes is studied. The effects of various means of mass pickup and of various wave forms of driving current are included in the analysis. A comparison of the theoretical predictions with experimental results reveals the importance of materials eroded from the components of the driver. Snowplough theory is also found to predict the observed motion of the decelerating plasma fairly accurately when the initial pressure in the shock tube is low and the mass of the driver gases large. The proposed model for the decelerating plasma is suggestive of one reason, a large mass of driver gases present, why various workers have obtained different values for β in the often-quoted relation [Formula: see text].
NUCLEAR MAGNETIC RESONANCE STUDY OF FERROELECTRIC LITHIUM HYDRAZINIUM SULPHATE, Li(N2H5)SO4
Authors: Cuthbert J. D. , Petch H. E.
Published: April 2011

The proton and Li7 nuclear magnetic resonance signals have been investigated in powdered samples and single crystals of lithium hydrazinium sulphate, Li(N2H5)SO4, which is known to be ferroelectric from −15 °C to above 80 °C.The quadrupolar splitting of the Li7 resonance, which was examined over the temperature range from −70 °C to +205 °C, undergoes rapid but continuous change between 80 °C and 160 °C indicating a crystal phase transition from a low to a high temperature polymorph. This transition is of the second-order type and completely reversible. The Li7 spectrum was examined in detail in the low and high temperature polymorphs at room temperature and +205 °C, respectively. The results have been analyzed and the quadrupole coupling constants, the asymmetry parameters, and the orientations of the principal axes of the electric field gradient tensors at the Li7 sites are reported.The second moment of the proton resonance in powdered Li(N2H5)SO4 at −183 °C was found to have a value of 39 ± 2 gauss2 which is consistent with the N2H5+ group existing as the hydrazinium ion NH2—NH3+ in an effectively rigid state. In the region of −130 °C, the second moment decreased rapidly to a little more than a third of its value at the temperature of liquid air. This effect is interpreted as resulting from the onset of rotation of the —NH3+ group about the N—N axis. As the crystal temperature was increased from −70 °C, the second moment remained virtually constant at 16.5 ± 0.5 gauss2 over a wide temperature range, began to decrease at +50 °C, paused slightly at a value of 8.8 ± 0.5 gauss2 at 150 °C, and again decreased rapidly to 0.74 ± 0.14 gauss2 at 210 °C. Our interpretation of the rapid decrease of the second moment between 50 °C and 150 °C is that it is caused by the onset of rotation of the —NH2 group about the N—N axis, which triggers the transition observed in the Li7 study. The very low value of the second moment at high temperatures indicates that the protons become highly mobile, probably diffusing by transfer from one hydrazinium ion to another along the c axis.The fine structure of the proton resonance obtained with a single crystal at room temperature was studied at selected crystal orientations. From these measurements, the H—H distances were inferred to be 1.67 ± 0.01 Å in the —NH3+ group and 1.64 ± 0.02 Å in the —NH3+ group. Assuming tetrahedral bond angles, this implies N—H distances of 1.03 ± 0.01 Å and 1.01 ± 0.01 Å in the —NH2 and —NH3+ groups, respectively.A possible mechanism for the ferroelectric behavior of lithium hydrazinium sulphate is suggested.
MEASUREMENT OF THE COMPLEX DIELECTRIC CONSTANT AT 8 mm: THE INTERFEROMETRIC AND STANDING-WAVE METHODS
Authors: Rao V. Muralidhara
Published: April 2011

An interferometric method has been developed for the measurement of ε′ and ε″ at 8.3-mm wavelength. The values obtained by the method are compared with those obtained by the standing-wave method. The agreement is fair.
MUTUAL NONLINEAR INTERACTION OF A NUMBER OF ELECTROMAGNETIC WAVES IN A PLASMA
Authors: Sodha Mahendra Singh , Palumbo Carl J.
Published: April 2011

In this communication the authors have obtained an expression for current density in a slightly ionized uniform plasma in the presence of a number of electric fields of different frequencies by solving the appropriate Boltzmann's equation. This expression along with the wave equation has been used to investigate the nonlinear mutual interaction of a number of electromagnetic waves, propagating in a plasma. Limitations of the present analysis have also been indicated and the physical significance of the results has been discussed. The technique has also been applied to investigate the mutual interaction of amplitude-modulated waves, and the results express a generalization of Luxembourg effect to a number of strong modulated waves.
CALCULATION OF THE PRESSURE TENSOR IN A FULLY IONIZED PLASMA
Authors: Shkarofsky I. P.
Published: April 2011

The tensor part of the pressure arising from gradients in flow velocity is calculated from the Fokker–Planck equation by using the Cartesian tensor expansion in direction cosines of the intrinsic velocity vectors and the Laguerre expansion for the magnitude of the intrinsic velocities. Wavelike perturbations and magnetic fields are included and both the electron and ion pressure tensors are investigated. The results are compared with those derived by other approaches.
CONSISTENT MODEL FOR PbS PHOTODETECTORS: I. EXPERIMENTAL RESULTS
Authors: Giroux Guy
Published: April 2011

An experimental study on PbS photodetectors—of the Ektron type—is reported. The results show that the ratio of the responsivity over the conductance multiplied by the time constant is temperature-independent between 300° K and 80° K. This is shown to be consistent with the experimental results obtained on different types of PbS cells and explained by either the number or the barrier theory. The actual contradictions are removed by a new model to be proposed in Part II of this study.
INVESTIGATIONS DURING 1962 OF THE ALERT ANOMALY IN GEOMAGNETIC VARIATIONS
Authors: Law L. K. , DeLaurier J. , Andersen F. , Whitham K.
Published: April 2011

Magnetic variations measured at three stations across the strike of the anomaly in electrical conductivity of the earth's mantle suggested by Whitham and Andersen (1962) near Alert, Ellesmere Island, have been analyzed by simple potential theory. The anomalous internal contributions to the magnetic variation vector show striking confinement consistent with an underground current in a northeast–southwest direction at a depth between 50 and 70 km, a few kilometers southeast of Alert. If the anomalous conductor is approximated by a uniform infinite cylinder, the horizontal field response as a function of frequency can then be explained with a conductivity of [Formula: see text] e.m.u. and a cylindrical radius of about 50 km. The vertical field response is, however, an unsatisfactory fit to this model. A possible asymmetry is noted based on the hourly range data: this could be explained by the dipping of the real conductor under Ellesmere Island.Preliminary earth potential measurements show that, as expected, the electric field variations are abnormally low at Alert.The gravitational consequences of the cylindrical model are discussed and compared with two profiles from the same region. A Bouguer anomaly is found in the predicted region if certain regional gradients are assumed, but its magnitude is smaller than that predicted from the cylindrical model in hydrostatic equilibrium. It is clear that approximate agreement can be obtained with crustal thinning of some 20 km.The significance of the thermal anomaly thought to be responsible for the electrical conductivity anomaly is discussed briefly.
EFFECT OF HIGH PRESSURES ON THE INFRARED AND RED ATMOSPHERIC ABSORPTION BAND SYSTEMS OF OXYGEN
Authors: Cho C. W. , Allin E. J. , Welsh H. L.
Published: April 2011

Absorption intensities in the 0–0 and 1–0 bands of the infrared [Formula: see text] and the 0–0 band of the red [Formula: see text] band systems of oxygen were measured in the pure gas in the range 50 to 150 atm and in O2–N2, O2–A, and O2–He mixtures up to 3000 atm total pressure at 25 °C. The integrated absorption coefficient of each band is expressed as a power series in ρO2 and ρf, the Amagat densities of oxygen and the foreign gas, respectively. The coefficient of the linear term AρO2 is a measure of the intrinsic (magnetic dipole) absorption of the O2 molecule; it is much greater in the red than in the infrared system. The quadratic term, BρO22, gives the induced absorption in O2–O2 pairs; B is about ten times greater in the infrared than in the red system. These results explain intensity anomalies which have been observed in condensed oxygen. Induction effects in O2–N2 and O2–A pairs are much smaller than in O2–O2 pairs, and scarcely observable in O2–He pairs. The significance of these results is discussed.
SPIN-ORBIT SPLITTING AMONG CERTAIN LIGHT NUCLEI DUE TO THE TWO-BODY SPIN-ORBIT POTENTIAL
Authors: Kunz P. D.
Published: April 2011

The separation of doublet levels in the mass 5, 6, 14, 15, and 17 systems is calculated from recent semiphenomenological potentials. Shell-model harmonic-oscillator functions are used to represent the nucleons. These wave functions are modified by means of correlation functions which vanish whenever any two nucleons approach closer than the hard-core radius and approach the unmodified oscillator function for large nucleon separations. It is found that the two-body spin-orbit potentials give 50 to 70% of the experimentally observed splittings.
NOCINTOGRAPH
Authors: Kulkarni P. V. , Barnes J. C.
Published: April 2011

A new instrument called a Nocintograph (Nocturnal Intensity Recorder) is described. This instrument scans the entire dome of the sky and records the intensities of the night sky radiations in four wavelengths several times during a night according to a predetermined program. Test records obtained on this instrument are presented and briefly discussed.
NUCLEAR SPIN RELAXATION IN GASES AND LIQUIDS: III. MOMENTUM-DEPENDENT INTERACTIONS
Authors: Oppenheim I. , Bloom M. , Torrey H. C.
Published: April 2011

A momentum-dependent interaction has been used by Torrey to explain the Xe129 nuclear spin relaxation measurements of Carr and co-workers. T1 is calculated here for this interaction for gases and liquids using the constant-acceleration approximation. The gas results are in good agreement with Torrey's exact calculation for a gas of hard spheres, and have the advantage of being usable with more realistic interatomic potentials. The results for the liquid are in good agreement with experiment.
A MODEL OF GEOMAGNETIC MICROPULSATIONS WITH LONG PERIODS
Authors: Jacobs J. A. , Watanabe T.
Published: April 2011

A physical process whereby a hydromagnetic oscillation of a magnetic line of force passing through the auroral zones gives rise to a system of ionospheric currents is described in this paper. Geomagnetic micropulsations, at least in middle and low latitudes, are claimed to be due to ionospheric currents thus produced. Observational evidence in support of this viewpoint for micropulsations in the daylight hemisphere is provided by the solar eclipse effect that the intensity of micropulsations is weakened in the eclipsed zone. The phase relationship between micropulsations in the north–south component and oscillations in the received frequency of a radio wave which is emitted from a station with a stable frequency of the order of several to tens of megacycles, and is propagated through the ionosphere, is correctly interpreted by the above theory.
A SOLAR RADIO POLARIMETER OPERATING AT 74 MC/S
Authors: Bhonsle R. V. , McNarry L. R.
Published: April 2011

A time-sharing radio polarimeter operating at 74 Mc/s is described. A cross-polarized equatorially mounted Yagi antenna is used and by means of electronic switching techniques suitable phase delays are introduced in the r.f. system to yield six components of polarization. Using these data, it is easy to calculate the Stokes parameters, which completely define the state of polarization of the incoming radiation. Originally the bandwidth used was 100 kc/s, but recently it was reduced to 10 kc/s. Some polarimeter recordings of solar noise bursts made at the Algonquin Radio Observatory are discussed.
THE Sr88(d, p)Sr89 REACTION
Authors: Preston R. L. , Sampson M. B. , Martin H. J.
Published: April 2011

Thirteen energy levels in Sr89 were excited by the Sr88(d, p)Sr89 reaction. The excitation energies of the levels are 0, 1.04, 2.00, 2.44, 2.67, 3.18, 3.45, 3.74, 4.10, 4.44, 4.60, 4.97, and 5.38 Mev. The ground-state Q-value is 4.15 ± 0.04 Mev. Angular distributions were measured for protons leaving Sr89 in the first three levels and for the 3.74-Mev state. Spin assignments were made using the shell model and the DWBA stripping theory. The assignments are 2d5/2 for the ground state, 3s1/2 for the 1.04-Mev state, 2d3/2 for the 2.00-Mev state, and [Formula: see text] for the 3.74-Mev state. The results are compared with analogous data on Zr91 levels.
THE SELF-CONSISTENT MATHIEU PROBLEM
Authors: Vail J.
Published: April 2011

The one-dimensional many-fermion system with weak attractive interaction, which is known to have self-consistent Hartree solutions corresponding to either uniform or spatially periodic mass density, is discussed as a physical model and as a mathematical problem. The Hartree problem for sinusoidal mass density leads to the self-consistent Mathieu problem, which is analyzed for the case where the first Brillouin zone boundary does not necessarily coincide with the Fermi surface (no energy gap between ground and single-particle excited states). The Mathieu equation is solved in the weak-binding approximation in the vicinity of the two lowest band gaps, the self-consistency condition is analyzed in detail, and the N-particle energy is calculated for various cases. The results suggest that the periodic state will not have lower energy than the uniform state unless the first gap in the one-particle spectrum lies near the Fermi surface. The fact that self-consistency can be obtained for a considerable range of periodicities suggests that the periodic solutions may be of importance in some many-fermion systems.
ROTATIONAL STRUCTURE OF SINGLET–TRIPLET TRANSITIONS IN NEAR SYMMETRIC TOPS
Authors: Hougen Jon T.
Published: April 2011

Expressions are presented for the intensities of the rotational lines in singlet–triplet transitions in molecules which belong to asymmetric-top point groups, but which are nevertheless near symmetric tops. The general selection rules for the rotational branches in such singlet–triplet transitions are: ΔN = 0, ± 1, ± 2 and ΔK = 0, ± 1, ± 2. They differ from the selection rules for singlet–singlet transitions in near symmetric tops by the occurrence of branches with ΔN = ± 2 and ΔK = ± 2. For certain asymmetric-top molecules, it is possible to divide transitions into two mutually exclusive types: those characterized by the selection rules ΔK = 0, ± 2 and those characterized by ΔK = ± 1.
RELAXATION TIME AND SOLUTION OF GUERNSEY–BALESCU EQUATION FOR HOMOGENEOUS PLASMAS
Authors: Rosenberg R. L. , Wu Ta-You
Published: April 2011

The kinetic equation of Guernsey–Balescu for spatially homogeneous plasmas is solved as an initial value problem in the linearized approximation. The distribution functions F1 for the electrons and the positive ions are expanded in series of associated Laguerre polynomials in the momentum, with coefficients which are functions of the time. The solution of the (infinite) systems of linear equations for these coefficients leads to the "spectrum of relaxation times". The damping constants vary from 10−4 to 0(1) in units of (v/rD3)ω, where v is the "volume per particle", rD is the Debye length, and ω is the plasma frequency of the electrons ω2 = 4πe2/vm. Numerical results are given for a few finite numbers of terms in the expansions of F1. For a homogeneous plasma with a given initial velocity distribution, the asymptotic approach, after an initial rapid damping, to the Maxwellian distribution has a relaxation time of the order 104(rD3/vω).The results of the present calculation and the question of the appropriateness, in the case of ionized gases, of the use of the Bogoliubov "initial condition" and "functional Ansatz" in the formulation of a theory of irreversible processes are discussed.
PROTON MAGNETIC RESONANCE IN PARAMAGNETIC AND ANTIFERROMAGNETIC CoCl2∙6H2O
Authors: Sawatzky E. , Bloom M.
Published: April 2011

The transition temperature TN of CoCl2∙6H2O was measured as a function of applied field and crystal orientation using the proton resonance lines, since they are very sensitive functions of temperature near TN. TN was found to be a complicated function of the applied field and crystal orientation, which cannot be described by the molecular field approximation. The transition is gradual rather than sudden and coexistence of the NMR spectra associated with the paramagnetic and antiferromagnetic phases was observed over a temperature region of about 10−2 °K. Short-range order effects were observed near TN in the form of anomalous broadening of the magnetic resonance lines. The magnetic susceptibility in zero field was measured along the preferred axis of antiferromagnetic alignment. This, together with specific heat data from published literature, was used to show a mutual consistency between thermodynamic variables and the dependence of TN on H in low fields as obtained by NMR. The treatment follows that of Buckingham and Fairbank for the λ transition in liquid helium. The sublattice magnetization in the antiferromagnetic phase was measured as a function of temperature. It was found to depend logarithmically on (TN – T), for all values of applied field.
THE DISINTEGRATION OF VORTEX RINGS
Authors: Magarvey R. H. , MacLatchy C. S.
Published: April 2011

The mechanism by which a mature ring is obliterated as it collides with a plane, rigid surface parallel to the plane of the ring is inferred from photographic sequences. The absence of turbulent mixing at the surfaces demarcating the layers makes it possible to trace the deformations throughout the entire process. The predominant feature of the changing geometry is the sharpness of the bounding surfaces. The violent disintegration process is not only interesting in its own right, but information regarding the nature and structure of the layers and the ring itself is obtained from an examination of the events leading to its destruction.
THE MEASUREMENT AND ANALYSIS OF TRIPLE CORRELATIONS
Authors: Smith Philip B.
Published: April 2011

The measurement and analysis of the intensity–direction correlation of gamma rays emitted in cascade following heavy-particle capture are treated. A procedure is discussed which is based upon the expansion of the triple-correlation intensity in terms of the set of angular functions orthogonal over the space of the emission (or absorption) directions. This is in contrast to the usual method which expresses the correlation in terms of Legendre polynomials. In the analysis procedure proposed, the population parameters are found directly from the original data, with the gamma-radiation mixing ratios assigned. The least-squares equations representing the best fit to the data contain the population parameters linearly and are solved by a standard computer program which also gives the value of χ2. The true solution is then found by varying the mixing ratios until a minimum in χ2 is reached. In addition to the determination of the population parameters of the decaying state and the mixing ratios of the gamma rays in the cascade, the calculation of the error matrix of these quantities, and the calculation of the formation parameters in simple capture, are described.
ON THE TIME-DEPENDENT BOLTZMANN EQUATION FOR ELECTRONS AND PHONONS
Authors: Simons S.
Published: April 2011

It is shown that the solution of the time-dependent Boltzmann equation for an arbitrary initial distribution tends to the stationary-state solution with the passage of time. The explicit time variation of the distribution is obtained in certain cases, and the significance of the results is discussed.
NONLINEAR GROWTH OF THIRD HARMONIC OF AN ELECTROMAGNETIC WAVE IN A PLASMA
Authors: Sodha Mahendra Singh , Palumbo Carl James
Published: April 2011

Using the recent results of Rosen (1961), the authors have obtained an expression for the nonlinear current density in a slightly ionized plasma due to an electric held E = E1 exp (iωt) + E3 exp (3iωt). This expression has been substituted in the wave equation and the resulting nonlinear differential equations have been solved by the method of successive approximations, to obtain an explicit expression for the growth of the third harmonic of an electromagnetic wave in a plasma.
ANNIHILATION OF POSITRONS IN LIQUID HELIUM AND THE POSITRON–HELIUM BOUND STATE
Authors: Khare H. C. , Wallace P. R. , Bach G. G. , Chodos A.
Published: April 2011

It is shown that it is possible for a positron to form a bound state with a helium atom, with a binding energy of about 0.55 electron volt. The lifetime of positrons in liquid helium is substantially longer than the predicted lifetime for annihilation from this state, indicating that capture into such a state takes a time considerably longer than the annihilation lifetime. On the other hand, the observed lifetime implies an electron density at the positron larger than the mean electron density in the material, consistent with the expected attraction of the positron toward the helium atom.
THE EXACT SOLUTION OF SOME LATTICE STATISTICS MODELS WITH FOUR STATES PER SITE
Authors: Betts D. D.
Published: April 2011

Statistical mechanical ensembles of interacting systems localized at the sites of a regular lattice and each having four possible states are considered. A set of lattice functions is introduced which permits a considerable simplification of the partition function for general nearest-neighbor interactions. The particular case of the Potts four-state ferromagnet model is solved exactly in two dimensions. The order–disorder problem for a certain quaternary alloy model is also solved exactly on a square net. The quaternary alloy model has the interesting property that it has two critical temperatures and exhibits two different types of long-range order. The partition function for the spin-3/2 Ising model on a square net is expressed in terms of graphs without odd vertices, but has not been solved exactly.
HOLLOW ANODE LITHIUM LAMP
Authors: Sullivan H. M.
Published: April 2011

A hollow anode source of resonance radiation providing a brilliant stable illumination at a wavelength of 6708 Å is described. Such a source is suitable for calibration of photometers employed to study twilight lithium phenomena or for rocket cloud experiments in which atomic lithium is released. Linewidths are narrow enough to reveal easily the doublet nature of the lines, and self-absorption effects appear to be small, so that the lamp should be useful for studying isotopic compositions. Minor modifications render it possible to observe lines other than those of lithium, thus extending the field of usefulness of this type of lamp construction.
AN APPARENT ANOMALY OF THE BAROMETRIC COEFFICIENT FOR THE NUCLEONIC COMPONENT OF COSMIC-RAY INTENSITY
Authors: Lapointe S. M.
Published: April 2011

A statistical analysis, based on three and one-half years of observational data, previously published by Lapointe and Rose (1962), produced a larger barometric coefficient for the nucleonic intensity in the standard neutron monitor at Sulphur Mountain (altitude 2283 meters) than at Ottawa (same geomagnetic latitude, sea level station).To explain this apparent anomaly, a simple theoretical model is presented which reproduces the results of this statistical analysis. The model treats the nucleonic component as consisting of two distinct cascades of nucleons, one "hard", characterized by a greater attenuation length and smaller pressure coefficient, and one "soft", characterized by a shorter attenuation length and larger pressure coefficient. The validity of the model is discussed.
OPTICAL ENERGY-GAP VARIATION IN InAs–InSb ALLOYS
Authors: Woolley J. C. , Warner J.
Published: April 2011

Homogeneous samples of InAs–InSb alloys have been produced by very slow directional freezing and zone recrystallization methods, and used for the determination of values of the optical energy gap Eg by standard infrared transmission measurements. Room-temperature values of Eg have been obtained in the composition ranges 0–20 and 55–100 mol % InSb and the variation of Eg with temperature from 90 °K to 360 °K for alloys in the composition ranges 0–20 and 80–100 mol % InSb. Approximate room-temperature values of Eg for alloys in the range 20–55 mol % InSb have been obtained by diffuse reflectivity measurements on annealed powders.The value of Eg is found to fall as either compound is added to the other and the room-temperature values show a minimum of 0.10 eV at approximately 60 mol % InSb.
CRYSTAL STRUCTURE OF ZIRCONIUM TRICHLORIDE
Authors: Swaroop B. , Flengas S. N.
Published: April 2011

The crystal structure of zirconium trichloride was determined from X-ray diffraction patterns. Zirconium trichloride belongs to the [Formula: see text]space group. The dimensions of the main cell at room temperature are: a = 5.961 ± 0.005 Å and c = 9.669 ± 0.005 Å.The density of zirconium trichloride was measured and gave the value of 2.281 ± 0.075 g/cm3 while, from the X-ray calculations, the value was found to be 2.205 g/cm3.
EXCHANGE CORRECTIONS AND THE CONVERGENCE OF THE PERTURBATION EXPANSION FOR THE MOMENTUM DISTRIBUTION FUNCTION FOR AN INTERACTING ELECTRON GAS AT METALLIC DENSITIES
Authors: Geldart D. J. W. , Houghton A. , Vosko S. H.
Published: April 2011

The ground-state momentum distribution of an interacting electron gas at metallic densities is investigated by means of many-particle perturbation theory. Approximation methods and computational techniques are developed for the evaluation of the leading exchange corrections to the Random Phase Approximation. It is concluded that the straightforward perturbation expansion, which includes only single direct and exchange self-energy insertions, does not converge at the lower metallic densities and that it is necessary to include "higher-order" effects by renormalizing the electron propagator. When this is done, a large gap at the Fermi surface remains in the momentum distribution even for rs ~ 6.
THE DISTRIBUTION OF IONIZATION ALONG UNDERDENSE METEOR TRAILS
Authors: Rice D. W. , Forsyth P. A.
Published: April 2011

Attempts to use the decay of radio signals reflected from individual meteor trails to study the upper atmosphere have revealed a puzzling inconsistency in the signal behavior. An earlier paper pointed out that this inconsistency remained even when the previously postulated sources of error were eliminated. As a result, an irregularly ionized trail model was proposed and shown, by calculation of signal characteristics, to be capable of accounting for the observations. This paper presents results of a new experiment which permitted the determination of the ionization profiles as the meteor trails were formed. The predicted irregularities were found, even for trails which exhibited apparently "ideal" underdense signal characteristics.
RADIATION FROM A SOURCE NEAR A PLANE INTERFACE BETWEEN AN ISOTROPIC AND A GYROTROPIC DIELECTRIC
Authors: Seshadri S. R. , Hessel A.
Published: April 2011

The radiation from a line source of magnetic current situated in free space near a plane interface between a semi-infinite free space and a semi-infinite gyrotropic dielectric is investigated for the case in which the gyrotropic axis is parallel to the line source. In addition to the space waves, it is found that in general two unidirectional surface waves are excited along the interface. The dispersion relations for the space and the surface waves are thoroughly examined. Both surface waves have different high-frequency cutoff but no low-frequency cutoff. The characteristics of these surface waves are investigated. An asymptotic evaluation of the total electromagnetic field is carried out for a particularly simple choice of the source frequency. For this frequency, the dependence of the efficiency of excitation of the surface waves on the distance of the source from the interface is determined. The radiation patterns are plotted for various values of the static magnetic field and the position of the source.
ON THE THEORY OF DIFFUSION IN A MAGNETIC FIELD
Authors: Youdelis W. V. , Colton D. R. , Cahoon J.
Published: April 2011

Diffusion in the weakly paramagnetic aluminum (rich) – copper system has been investigated in a magnetic field. Aluminum – aluminum/3% copper solid diffusion couples were diffusion annealed in a magnetic field of 30 and 20 kilo-oersteds, and then analyzed for diffusion using a microhardness technique. A statistically significant 25% decrease in the diffusivity was found for the couples annealed in a 30-kilo-oersted field applied perpendicular to the diffusion direction. However, from the accuracy of the results it is not possible to determine whether the field affects only the frequency factor D0, the activation energy E, or both factors. A theory based on the plasma–agnetohydrodynamic properties of the alloy system is developed to explain the results. According to the theory, the magnetic field decreases the diffusivity by the factor 1/(1 + ωce2/νe2), where ωce and νc are the cyclotron and collision frequencies respectively of the diffusion-transported electrons. The plasma-oscillation screening effect is discussed, and it is shown that the field does not significantly affect charge screening. It is thus proposed that the diffusivity is decreased through the frequency factor D0, and not through the activation energy of the atom-vacancy jump process.
A SURFACE LAYER MODEL FOR THE TOTAL RESISTIVITY OF THERMOMETRIC-GRADE PLATINUM WIRE
Authors: Lovejoy D. R.
Published: April 2011

A model for the temperature dependence of the total resistivity of thermometric-grade platinum wire is developed. The evidence supports as a basic model the two-electronic conduction-band theory of Sondheimer and Wilson. However, in the small-diameter (~80 μm) wire, here considered, surface contamination would lead to deviations from the simple model. A theory of multiple conduction bands, due to surface contamination, has been developed. The theory enables us to infer, from known calibration data on platinum resistance thermometers, that there are two regions of contamination. One is a region of heavily concentrated impurity over a few atomic layers at the surface, which accounts for variations in resistivity near 700 °K. The other is a subsurface layer about 0.1 μm thick with about 0.1% impurity level, which accounts for variations in resistivity in the region of 90 °K.
QUANTUM AND CORRELATION CORRECTIONS TO THE THOMAS–FERMI POTENTIAL
Authors: Viswanathan K. S. , Achar B. N. Narahari
Published: April 2011

The paper studies the correction to the Thomas–Fermi potential arising from the exchange, inhomogeneity, and correlation effects. An alternative derivation of the Baraff equation is given, based on simple physical considerations. Starting from the Baraff equation and making use of the simple analytical formula of Tietz for the Thomas–Fermi potential, analytical expressions for the correction to the Thomas–Fermi potential are given (a) within the radius of the atom applying the Gellmann–Brueckner high-density formula for the correlation energy of an electron gas and (b) outside this range wherein the correlation energy can be approximated by the Wigner low-density formula. It is found that the main contribution to the solution of the Baraff equation arises from the inhomogeneity, screening, and the exchange terms.
SCATTERING BY A CYLINDRICAL GAUSSIAN POTENTIAL: EXACT SOLUTION
Authors: Brysk Henry , Buchanan Mary L.
Published: April 2011

The scalar wave equation has been solved exactly for scattering by a repulsive cylindrical Gaussian potential, the phase shifts being evaluated and summed for backscatter on an IBM 7094 computer for a number of values of potential strength and range. The results are displayed in comparison with various approximations. Some implications for the interpretation of meteor-trail scattering are explored.
THE ABSORPTION SPECTRUM OF NO2 IN THE 3 700–4 600 Å REGION
Authors: Douglas A. E. , Huber K. P.
Published: April 2011

An investigation of the absorption spectra of both 14NO2 and 15NO2 has revealed a long progression of red-degraded bands in the region 3 700–4 600 Å. The rotational analysis shows that these bands are the Ka = 0 ← 1 subbands of the electronic transition 2B1 ← 2A1. The interpretation of the bands is discussed, and a few remarks concerning the onset of predissociation at 3 979 Å are added.
IMPROVED ATOMIC PHYSICS CALCULATIONS
Authors: Conkie W. R.
Published: April 2011

A method is developed for calculating the energy of a definite state of an N-electron system. The method uses a form of the Bethe–Goldstone equation to calculate the correlation energy of an interacting electron pair moving in the nuclear Coulomb field and in the average field of the other electrons. A calculation on the ground state of the lithium atom gives an energy which differs from the accurate value by less than 0.1%.