bluuebunny/crossref_metadata_2025 huggingface dataset:
THE INFLUENCE OF THE ELECTRON–ION INTERACTION ON THE PHONON FREQUENCIES OF SIMPLE METALS: Na, Al, AND Pb
Authors: Vosko Seymour H. , Taylor Roger , Keech G. Howard
Published: April 2011

The phonon frequencies of simple metals are calculated from an effective interaction between ions arising from the direct Coulomb interaction between ions and the conduction-electron response to the ion motion. The response of the electrons is treated by the many-body perturbation theory. The central quantity in the theory is the scattering amplitude for Bloch electrons from the displaced ions (electron–ion matrix element). The screening effects produced by the electron–electron interaction are taken over from the free-electron theory. The electron–ion matrix element naturally splits into two parts: the potential due to the conduction electrons within the Wigner–Seitz cell and the potential which enters the one-particle Schroedinger equation for the electrons in a periodic lattice. The former is the major term for small momentum transfer, [Formula: see text], and characterizes the magnitude of the screening contribution to the frequencies, while the latter dominates for large momentum transfer. This leads to a fundamental distinction between f c.c. and b.c.c. metals. To make numerical estimates, the electron wave functions are approximated by single orthogonalized plane waves. The importance of the k-dependence of the matrix element is investigated and found to be small for Na and Al, but substantial for Pb. The calculated phonon frequencies agree reasonably well with the experimental results. In addition the magnitude of the observed Kohn anomalies in Pb is explained.
LEVEL DENSITIES IN LIGHTER NUCLEI
Authors: Gilbert A. , Chen F. S. , Cameron A. G. W.
Published: April 2011

There has been discussion in the literature as to whether the cumulative number of levels in light nuclei varies more nearly as exp(const. [Formula: see text]) or exp(const. E), where E is the excitation energy. The question is examined in this paper. It is found that if one constructs "step diagrams" by plotting the cumulative number versus the energy, both formulas represent the data almost equally well. However, additional consideration of levels counted above neutron and proton binding energies shows that exp(const. [Formula: see text]) fails badly to represent the data, whereas exp(const. E) continues to give good fits. In either case E may be measured above an arbitrary ground-state energy E0. If the satisfactory formula is written in the form exp(E–E0)/T, then it is found that the dependence of the slope on mass number may be expressed in approximately the form T−1 = 0.0165A MeV−1, but there are significant deviations from this relation apparently related to shell structure. The intercepts E0 are quite variable but are roughly clustered according to the oddness or evenness of the neutron and proton numbers of the nucleus.
SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: III. ENERGY TRANSFER IN CESIUM–CESIUM COLLISIONS
Authors: Czajkowski M. , Krause L.
Published: April 2011

Collisions of the second kind leading to the transfer of excitation between 6 2P1/2 and 6 2P3/2 states in cesium have been investigated by studying sensitized fluorescence in cesium vapor at pressures in the range 2 × 10−6 to 7 × 10−5 mm Hg, which were not accessible previously to such experiments and at which trapping of resonance radiation is virtually absent. The use of an improved fluorescence tube and of high-resolution interference filters in conjunction with a liquid-air-cooled photomultipler tube permitted accurate measurements of extremely low fluorescent light intensities. The total cross sections for the processes 6 2P1/2 → 6 2P3/2 and 6 2P1/2 ← 6 2P3/2 equal 0.64 × 10−15 cm2 and 3.1 × 10−15 cm2 respectively and are in a ratio of 0.20, which agrees well with the value predicted by the principle of detailed balancing.
ROLE OF THE SYMMETRY ENERGY IN ATOMIC MASS FORMULAS
Authors: Cameron A. G. W. , Elkin R. M.
Published: April 2011

Cameron has interpreted the heavy uranium mass yield curve from the Mike thermonuclear explosion as indicating that conventional atomic mass formulas do not give realistic values of neutron binding energies for neutron-rich nuclei off the valley of beta stability. In this paper two mass formulas are constructed which differ in the treatment of the nuclear symmetry energy. In one, essentially of conventional form, very neutron-rich nuclei become unbound. In the other, of a modified "exponential" form, very neutron-rich nuclei remain slightly bound. The three adjustable coefficients in each formula were determined by least-squares fits to the measured masses near the valley of beta stability; the formulas fit these masses about equally well with nearly the same values of the coefficients. Additional shell and pairing corrections were determined empirically. These corrections suggest a preference for the exponential formula. Some astrophysical applications of these results are qualitatively discussed.
DIELECTRIC ESTIMATION OF HYDRATION AROUND NUCLEIC ACID
Authors: El-Sabeh S. H. M.
Published: April 2011

Microwave dielectric measurements were carried out at 1.26-cm and 3.28-cm wavelengths at 25 °C ± 0.1 °C on a solution of 2% concentration by weight of deoxyribonucleic acids in distilled water. It was found that the solution obeys the Debye equation and that the weight of water which is irrotationally bound to 1 g of nucleic acid is 0.08 ± 0.04 g.
THERMAL EXPANSION OF SINGLE CRYSTALS OF ZINC AT LOW TEMPERATURES
Authors: Channing D. A. , Weintroub S.
Published: April 2011

The linear thermal expansion coefficients αψ of two single crystals of Zn of orientations ψ = 10.8° and 63.9 ° with the hexad axis were measured over the temperature range of about 20–270 °K using an absolute Fizeau optical interference technique. The two principal coefficients, [Formula: see text] and [Formula: see text], corresponding to ψ = 0° and 90 ° respectively, were calculated from the Voigt relation, and their values are compared with previously reported experimental data. Above 60 °K there is good agreement with previous work, and below 60 °K the results confirm, in general, the data obtained by McCammon and White. The Grüneisen parameter γ is essentially constant at about 2.1 in the range 100–270 °K, but below 100 °K γ rises appreciably with decreasing temperature and reaches the value of about 3.5 at 20 °K.
INTERNAL FRICTION STUDY OF ALUMINIUM ALLOY CONTAINING 7.5 WEIGHT PERCENT MAGNESIUM
Authors: Dey B. N. , Quader M. A.
Published: April 2011

Low-frequency internal-friction data were obtained using the torsion pendulum for the aluminium −7.5 wt% magnesium alloy in order to study the effects of quenching and aging on solute atom movements. A damping peak near 120 °C, attributed to the stress-induced reorientation of solute atoms (Zener relaxation), was found to shift to 80 °C on quenching. The activation energy for the peak at 80 °C was found to be 22.3 ± 1.5 kcal/mole, about 3 kcal/mole less than that for the Zener peak. The peak shift was found to be due to movement of solute atoms involving divacancies with reduced relaxation time. Aging of the quenched alloy at room temperature for one day was found sufficient to eliminate the effect of quenching in reducing relaxation time.Another weak damping peak near 40 °C in the as-quenched alloy specimen, attributed to the relaxation involving solute clusters, was found to be more pronounced on aging at room temperature for 24 hours, thereby indicating formation of zones in the quenched alloy during aging at room temperature. It was inferred from the results that about 100 atomic jumps were required to complete the relaxation responsible for this peak.Grain-boundary peaks were also observed in the furnace-cooled and the water-quenched specimens.
GEOMAGNETIC MICROPULSATIONS IN THE AURORAL ZONES
Authors: Wright C. S. , Lokken J. E.
Published: April 2011

This report deals with micropulsation data measured at Fort Churchill and at the near-conjugate stations of Byrd and Great Whale River during the conjugate-point experiment by Stanford University and Pacific Naval Laboratory. All three stations are in the auroral zones; and the data, though discontinuous, cover the period from 1961 to 1963.On the assumption that near-coincidence in time of events should be displayed at two conjugates, attention has been concentrated on the times of occurrence of the relatively numerous polar sudden commencements which often introduce the negative bays. There is a striking and very persistent diurnal variation, with maximum occurrence in the hours 03 to 04 G.M.T., which shows at all three stations, but most clearly at the two conjugates.A small time difference, of about one minute on the average, is apparent between events measured at Byrd and those at Great Whale. There is a tendency for the events to be preceded by a quiet period, and they correspond to sudden changes shown on local magnetograms, and lead to a similar diurnal variation of the magnetic elements H, D, and V. A similar pattern appears in the sudden changes of ionospheric absorption shown on the riometer records from Cape Jones, which is about 180 km from Great Whale Rive; but adequate data for individual time differences are lacking. The coincidence of nighttime active auroras and micropulsation polar-storm commencements measured at the same station seems to be very close. The quiet daytime auroras often show coincident pulsations of light intensity of the same period as the regular (Pc type) micropulsations.
BREAKDOWN OF A RADIO-FREQUENCY DISCHARGE IN THE PRESENCE OF A SUPERIMPOSED d-c. FIELD
Authors: Sen S. N. , Bhattacharjee B.
Published: April 2011

Breakdown voltages have been determined in the case of some rare gases (He, Ne, A) and oxygen at a constant pressure (10 mm Hg) when excited simultaneously by a radio-frequency field (frequency 10 Mc/sec) and a variable d-c. field. It is found in all cases that the breakdown voltage is higher when both the fields are present than when the gases are excited by the radio-frequency field alone and the breakdown voltage gradually increases with the increase of the applied d-c. field. The variation of breakdown field with d-c. field is of the same nature in all of the gases studied. A theoretical expression for the breakdown voltage in the presence of both the r-f. and d-c. fields has been deduced from the theory of electrical discharge by Kihara (1952) together with the expression of equivalent length as deduced by Varnerin and Brown (1950). The theoretical expression cannot explain satisfactorily the experimental results, and the rate of rise of breakdown voltage in the d-c. field as obtained from theory is smaller than that obtained from experimental results. The discrepancy has been ascribed partly to the uncertainty in the values of the numerical constants introduced by Kihara and also to the increase of diffusion caused by the presence of positive ions—a factor which has not been taken into consideration in the present treatment.
LIFETIMES OF THE 16O 6.13-MeV LEVEL AND THE 17O 0.871-MeV LEVEL
Authors: Alexander T. K. , Allen K. W.
Published: April 2011

The mean lifetimes of the 0.871-MeV state of 17O(E2) and the 6.13-MeV state of 16O(E3) have been measured by a new recoil method using a Ge(Li) gamma-ray detector. The data yield mean lifetimes of (2.33 ± 0.27) × 10−10 and (2.5 ± 0.2) × 10−11 sec for the states in 17O and 16O respectively. The recoil method is generally applicable to the measurement of lifetimes greater than about 5 × 10−12 sec and provides a technique for a region of time where neither direct electronic timing nor Doppler-shift attenuation methods are accurate.
VORTICES IN SPHERE WAKES
Authors: Magarvey R. H. , MacLatchy C. S.
Published: April 2011

The formation and structure of vortices characteristic of sphere wakes corresponding to a range of Reynolds numbers extending from 200 to 500 have been examined. The manner in which vorticity is released to the free stream has been deduced from the photographic evidence. It has been found that, over the entire range of Reynolds numbers considered, at least part of the vorticity generated in the boundary layer is transferred to the stream by means of an involved sheet. This sheet is distorted continuously by the backflowing fluid and reappears as the demarcating surface of the vortex elements of the wake. The spiraling path was found to be associated with the asymmetry relative to the upstream–downstream axis of the sphere.
LES COMPOSANTES DE L'IMAGE PRODUITE PAR UN SYSTÈME D'OPTIQUE IONIQUE
Authors: Baril Marcel , Kerwin Larkin
Published: April 2011

Several theoretical studies have been made of the various components of the image formed by a magnetic prism-lens. This paper reports experimental measurements of the image formed by a 90 ° sector magnet. The contributions to the image caused by the finite object width, spherical aberration, chromatic aberration, curvature of fringing field lines, oblique rays, detector slit, and detector response time have been verified quantitatively. When account is taken of image alignment, and focusing locus, and when space charge is absent, the measured resolving power of the system verifies theoretical predictions.
EXPERIMENTAL DETERMINATION OF THE DIPOLE MOMENTS OF THE DEGENERATE STATES OF NH
Authors: Irwin T. A. R. , Dalby F. W.
Published: April 2011

Light from the high-field region of a Lo Surdo discharge in ammonia was focused on the slit of a stigmatic spectrograph. Spectrograms of the 3 360 and 3 240 Å bands of NH and the hydrogen line Hβ were taken simultaneously. From observations of the molecular and atomic hydrogen Stark splittings and intensities the electric dipole moments of the degenerate states of NH were determined to be μ(A3Π) = (1.31 ± 0.03), μ(c1Π) = (1.70 ± 0.07), μ (a1Δ) = 1.49 ± 0.06) Debye, where the signs of μ(c1Π.) and μ(a1Δ) are the same.
ABSORPTION SPECTRUM OF THE CCN RADICAL
Authors: Merer A. J. , Travis D.N.
Published: April 2011

A new transient absorption spectrum, attributed to the CCN free radical, has been discovered in the flash photolysis of diazoacetonitrile, HC(CN)N2; three electronic transitions, between 3 500 Å and 4 700 Å, have been photographed for both CC14N and CC15N. The ground state of the radical is a 2Πr electronic state, and the three excited states observed are A2Δ, B2Σ−, and C2Σ+. The 2Π and 2Δ states show evidence of Renner–Teller interaction between the vibrational and electronic angular momenta, an effect not observed previously for 2Δ states. Theoretical expressions for the vibrational energy levels of linear triatomic molecules in 2Δ electronic states have been derived, in terms of a parameter η associated with the quartic terms in the potential energy. They are compared with the observed pattern in the ν2 = 1 level of the A2Δ state. The principal molecular constants for CC14N (in cm−1) are as follows:[Formula: see text]
VIBRATIONAL FREQUENCY PERTURBATIONS IN THE RAMAN SPECTRUM OF HYDROGEN
Authors: May A. D. , Poll J. D.
Published: April 2011

The influence of the lattice vibrations on the shift of the vibrational Raman lines in solid hydrogen and the influence of nonadditive intermolecular forces on the shift in hydrogen gas are investigated for freely rotating molecules in terms of the adiabatic approximation. It is shown that the experimental value for the shift in the solid (Soots et al. 1965) can be accounted for by introducing a reasonable value for the amplitude of the lattice vibrations. The effect of the nonadditive intermolecular forces on the shift in hydrogen gas is shown to be appreciable at high densities.
THE THERMAL EXPANSION OF ALKALI HALIDES
Authors: Meincke P. P. M. , Graham G. M.
Published: April 2011

Measurements have been made of the coefficient of linear thermal expansion of NaCl, Nal, KCl, and KBr over the temperature range from 7 °K to 300 °K. The measurements were made by monitoring the changes in length of a Fabry–Perot etalon, whose spacer was of the material being studied, as it slowly warmed from liquid-helium temperatures. The detectable change in length of the 2-in. specimen was about 2 Å. The results are analyzed by reducing them to values of the Grueneisen γ. The temperature variation of γ at high temperatures is used to obtain values of γ (2s), which are compared with new calculations on a rigid-ion model to give the best fit to the Born exponent for the non-Coulomb interionic potential. The data for low temperatures are not sufficiently accurate to justify detailed analysis; there is some indication that the apparent low-temperature limit of γ is, in fact, the value at a minimum.
RADIO FADING AND THE NATURAL ELECTROMAGNETIC BACKGROUND
Authors: Duffus H. J. , Boyd G. M. , Kinnear J. K.
Published: April 2011

A comparison is made between the natural geomagnetic background in the frequency range 0.006–0.6 Hz and fluctuations of the difference in received signal strength between the two magnetoionic modes of vertically incident broad-band radio signals in the range 6–16 MHz, observed at a single station near Victoria, British Columbia. At this station the following points were observed:1. During the daytime there is often a spectral component common to the radio-signal fluctuations and to the natural geomagnetic background, even during quiet magnetic times. There is seldom phase coherence, however, except for a few minutes at a time.2. There is a small but highly significant (1%) linear correlation R = 0.33 between all the hourly mean amplitudes of the radio-signal fluctuation level and the hourly mean amplitudes of the natural geomagnetic background. The correlation coefficient rises as high as R = 0.71 at 1400–1500 local time, when only a particular hour of each day is considered. It is concluded that geomagnetic micropulsations in this frequency range are a better indicator of r-f. fluctuations than is the local Kp.3. At night, there is a relationship between the occurrence of Pt's and of r-f. fluctuation, although their frequency components are not usually as closely related as are those of the daytime regimes.It is suggested that geomagnetic micropulsations can couple exospheric or auroral zone fluctuations into the upper E or F regions strongly enough to produce observable radio-signal fluctuations at mid-latitudes, even during magnetically quiet times.Lack of correlation between micropulsations and phase fluctuations of 18 kHz signals observed over an E–W 100-km path, and 80 kHz observed over an E–W 3 300-km path suggests that significant coupling does not extend down to the D region during magnetically quiet times.
ON THE DERIVATION OF THE COLLISION LIFETIME MATRIX
Authors: Gien Tran Trong
Published: April 2011

If the lifetime of a collision is defined as the difference between the times in which a particle moves in free space and under an interaction from a scattering center to the outside (or in the reverse direction), this paper shows that exactly the same relation between the lifetime operator Q and the scattering matrix S as was found by Smith (1960) can be derived. This can be done in a natural way provided that the time operator is defined as [Formula: see text] and the manifold of the asymptotic outgoing (or incoming) states is chosen to be the set of corresponding eigenstates. The part of the time needed for the particle moving freely from the scattering center to R is equal to R/v.
LOW-TEMPERATURE THERMOELECTRIC POWER OF HEAVILY DOPED n-TYPE GERMANIUM
Authors: Hedgcock F. T. , Mathur D. P.
Published: April 2011

A large, temperature-dependent component in the low-temperature thermoelectric power of heavily doped n-type germanium has been observed in the temperature region of liquid helium. All of the samples (6.8–62 × 1017 per cm3) exhibit a negative magnetoresistance in the low-temperature region which saturates at reasonably low magnetic-field values. On the basis of an assumed magnetic scattering, the magnetoresistance and magnetic susceptibility data have been analyzed in order to estimate the magnitude and concentration of the localized magnetic moment of the spin-scattering center, and also to estimate the exchange integral giving rise to the coupling between the mobile carriers and the localized impurity electrons. The resistivity behavior, in both a finite and zero magnetic field, appears to be best described by assuming an antiferromagnetic transition in the region of the thermoelectric anomaly. Attempts are made to interpret the observed temperature dependence of the thermopower. However, as yet, there is no quantitative theory to predict the thermoelectric behavior of a degenerate semiconductor in the presence of antiferromagnetic ordering.
THE NONLINEAR INTERACTION OF A RADIO-FREQUENCY WAVE WITH AN INHOMOGENEOUS PLASMA SLAB: II. NONLINEAR REFLECTION AND TRANSMISSION COEFFICIENTS OF AN INHOMOGENEOUS PLASMA SLAB
Authors: Papa Robert J. , Case Carl T.
Published: April 2011

When a radio-frequency plane wave is incident upon an inhomogeneous, lossy plasma slab, part of the electromagnetic energy is reflected, part is absorbed by the plasma medium, and part is transmitted. At sufficiently high power levels (about 1 watt cm2 at X-band frequencies), the equation of state of the plasma is altered, which produces a change in the effective dielectric constant of the medium. In the high-frequency limit, the effective dielectric constant of the medium is expressed as a function of the electron density and an effective collision frequency. The electron density and effective collision frequency at each point in the medium are functions of the electron temperature. In Part I, the electron temperature (Te) at each point (z) in the slab has been expressed in terms of the local value of E2/ω2, where E = electric field amplitude and ω = signal frequency, i.e., Te = Te(z, E2/ω2). Using the predetermined functional dependence of Te on z and E2/ω2, the electromagnetic field distribution and the net reflection and transmission coefficients of the plasma slab are computed by employing the Runge–Kutta technique to integrate Maxwell's equations numerically step by step. For each value of ω, relatively small changes in the reflection and transmission coefficient are produced as [Formula: see text] is increased up to a critical value of [Formula: see text], where Einc = incident electric field amplitude. For values of [Formula: see text] greater than this critical value, there is a sharp increase in the reflection coefficient and a sharp drop in the transmission coefficient.
THE STRUCTURE OF AGGREGATES—A CLASS OF 20-FACED SPACE-FILLING POLYHEDRA
Authors: Smith F. W.
Published: April 2011

An example is given of a class of partitions of space into polyhedral cells having an average of 20 faces each. The structure is derived from the Voronoi polyhedra of slightly distorted versions of the diamond lattice, which in turn are duals of the Delaunay simplices of the diamond lattice. A particular member of this class is described: it is a 20-faced stereohedron that packs to fill space by isometries including a rotation.
LASER INTERACTION WITH A MERCURY SURFACE
Authors: Silberg Paul A.
Published: April 2011

To understand better the effects produced by the interaction of pulsed laser energy with materials, an experiment was performed with a light pulse from a ruby laser and a mercury surface. No visible arc was observed with the use of a 50-joule 2.5-millisecond laser pulse; however, a mechanical impact was observed and photographed with a framing camera. From the still frames, an estimate of the impact energy was made.Several mechanisms were examined to account for the observed effect. A rapid vaporization process, producing a reaction force into the mercury surface, would seem to account for the observed phenomenon.
THE SPECTRUM OF SiH AND SiD
Authors: Verma R. D.
Published: April 2011

Two new systems of SiH and SiD in the regions around 3 250 Å and 2 050 Å in addition to the well-known 2Δ−2Π system have been recorded in absorption and their rotational analysis (except for the 2Δ−2Π system of SiH) has been carried out. The new states are 2Σ+ at T0 = 30 974.69 cm−1 and 2Δ at T0 = 48 603.46 cm−1. The rotational constants for all the states known in SiD have been determined. The upper limit of the dissociation energy of SiH has been fixed at 24 680 cm−1 by predissociation.
HELICONS IN n-TYPE SILICON AND GERMANIUM
Authors: Wallace P. R.
Published: April 2011

Using the self-consistent field method, the collective modes of the electrons in n-type silicon and germanium in a constant external magnetic field are calculated from the frequency- and wavelength-dependent conductivity tensor σ(ω, q) for simple symmetry directions. Because of the differing orientations of the longitudinal axes of the energy surfaces relative to the direction of the external field, there is, in general, more than one carrier involved, with the result that the helicon spectrum can have more than one branch. The minimum frequencies of the higher ("optical") branches depend on the effective mass parameters in a different way than do the cyclotron resonance frequencies. The frequency spectra of all collective modes are discussed in the long-wavelength limit.
THE IONOLUMINESCENCE OF MgO AND Zn2SiO4:Mn
Authors: Wijngaarden A. van , Bradley D. J. , Finney N. M. A.
Published: April 2011

The luminescence response of MgO and Zn2SiO4:Mn phosphors to bombardment with various ions was determined as a function of ion energy, for energies smaller than 100 keV. The light output of MgO was found to be proportional to the total energy transferred from the projectile to the electrons in the phosphor lattice. The light output of Zn2SiO4:Mn under ion excitation was found to be independent of the population of the electron traps immediately below the conduction band. This suggests that the ionoluminescence was caused by the excitation of the electrons in the host lattice.
ENERGY CONSIDERATIONS IN THE ELECTROSTATIC DISPERSION OF LIQUIDS
Authors: Ryce S. A. , Patriarche D. A.
Published: April 2011

For the dispersion of electrically surface charged liquid drops it is assumed that the final minimum energy state is accessible to the system.Asymmetric division into two drops of radius γ and xr is considered as well as symmetric dispersion into n droplets of equal radius, where n = 2, 3, 4. A parameter y is defined as y = Q2/(16πR3γ), where Q is the charge on the original drop of radius R and surface tension γ. It is shown that if x > 2 in an asymmetric binary division, the smaller of the two droplets formed may be unstable and divide again. Photographic evidence of a secondary division is given. For a symmetric dispersion, at y = 1, the formation of four droplets leads to an energy minimum, with a maximum number, nmax, of allowed droplets of 20. For values of y > 1, nmax rises sharply.Values of y are calculated, below which symmetric division into two, three, or four droplets is forbidden. The conclusion is reached that below y = 0.351 the only permitted process is asymmetric division into two droplets, and that there is no situation for which binary symmetric division leads to a lower final energy of the system than the other modes of dispersion.
THE LONG WAVELENGTH LIMIT IN SCATTERING FROM A DIELECTRIC CYLINDER AT OBLIQUE INCIDENCE
Authors: Wait James R.
Published: April 2011

The previously published exact expressions (Wait 1955) for scattering from a homogeneous dielectric cylinder are reduced to a simple form when the radius is very small compared with the wavelength. It is shown that, for this limiting case, the resonance scattering condition is independent of the polarization and angle of incidence of the incident wave.
THE 2 700 Å BANDS OF THE N3 MOLECULE
Authors: Douglas A. E. , Jones W. Jeremy
Published: April 2011

The 2 700 Å absorption bands found by Thrush in the flash photolysis of HN3 have been studied at high resolution. The rotational fine structure of the strongest band has been analyzed, and it has been shown that the bands arise from a [Formula: see text] transition of the N3 molecule. The bond distance in the ground state of N3 is found to be 1.181 Å.
THE ADMITTANCE OF A LINEAR ANTENNA IN A UNIAXIAL MEDIUM
Authors: Hurd R. A.
Published: April 2011

The admittance of a thin, long linear antenna embedded in a uniaxial medium and inclined at an angle θ to the medium's axis is calculated by solving an integral equation. It is shown that the admittance is roughly the same as for an isotropic region with a suitably modified relative dielectric constant given by Keff = √[K(sin2θ K3 + cos2θ K)], where K and K3 are the components of the relative permittivity tensor. Some numerical results are presented.
HEAT TRANSFER IN GAS-FILLED POWDERS AT LOW TEMPERATURES
Authors: Brodie D. E. , Mate C. F.
Published: April 2011

A cell model is developed for the discussion of heat transfer in uniform gas-filled powders at low temperatures. Calculations from the model are compared with measurements of the (average) thermal conductivity of powdered alumina in helium gas, at helium temperatures, under varying conditions of particle size, gas pressure, temperature, and load supported by the powder. The results at high pressures suggest the presence of a boundary resistance, similar to the Kapitza resistance, at the gas–solid interfaces within the powder.
1001 REACTIONS OF THE Ar AND Kr ION DOUBLETS
Authors: Hussain Masud , Kerwin Larkin
Published: April 2011

Ionization probability curves for Ar and Kr have been examined up to 1.5 eV above the ionization threshold using an electrostatic electron selector. Structure is observed between the Kr+ "ground" doublet levels and beyond the Ar+J = 1/2 level.Some of this structure is found to affect the 1001 collision cross section for these ions, which were measured in the primary ion energy range of 500–1 300 eV. The cross section for the J = 1/2 state is found to be larger than that for the J = 3/2 state in the case of Ar, while the reverse appears to be true for Kr.
A PLANE-WAVE ANALOGUE MODEL FOR STUDYING ELECTROMAGNETIC VARIATIONS
Authors: Dosso H. W.
Published: April 2011

A plane-wave analogue model for studying the effect that various geological structures have on the natural electromagnetic variations observed at the surface of the earth is discussed. The validity of the model is discussed, and measurements of amplitudes and phase angles are obtained for a model flat earth and for cylindrical bodies embedded in the surface layer.
A MULTILAYER CONDUCTING EARTH IN THE FIELD OF PLANE WAVES
Authors: Dosso H. W.
Published: April 2011

A multilayer plane conducting earth in the field of plane electromagnetic waves is treated. Each of several thick layers is divided into a sufficient number of sublayers, with changing conductivity, to represent to a good approximation a continuous change in conductivity. Expressions for the amplitudes and phases of the electric- and magnetic-field components are obtained and evaluated for several different conductivity distributions. The conductivities and frequencies considered are of interest in geophysics. The results obtained indicate that the amplitudes and phases of the varying electromagnetic-field components are affected strongly by the inhomogeneity of the conducting medium.
SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: V. ENERGY TRANSFER IN COLLISIONS BETWEEN CESIUM AND INERT GAS ATOMS
Authors: Czajkowski M. , McGillis D. A. , Krause L.
Published: April 2011

The total cross sections for excitation transfer between the 6 2P1/2 and 6 2P3/2 levels in cesium, induced by collisions of the second kind between cesium and inert gas atoms, have been determined using methods of sensitized fluorescence. The experiments were carried out at a cesium vapor pressure of 1 × 10−6 mm Hg, at which there is no trapping of resonance radiation, and over a range of inert gas pressures extending from 1 to 300 mm Hg. The cross sections Q1(2P1/2 → P3/2) and Q2(2P1/2 ← 2P3/2) are as follows: Cs–He: 5.7 × 10−21 and 3.9 × 10−20 cm2; Cs–Ne: 1.9 × 10−21 and 3.1 × 10−20 cm2; Cs–A: 1.6 × 10−21 and 5.2 × 10−20 cm2; Cs–Kr: 8.3 × 10−21 and 18.4 × 10−20 cm2; Cs–Xe: 7.2 × 10−21 and 27.4 × 10−20 cm2. A mechanism for the excitation transfer is suggested, which involves an interaction between the inert gas atoms and the 6 2P electron in cesium, behaving as a free particle.
PHONON BROADENING OF IMPURITY SPECTRAL LINES: III. DIAGRAM TECHNIQUE
Authors: Barrie Robert , Rystephanick R. G.
Published: April 2011

The theory of the phonon broadening of optical absorption lines associated with impurities in semiconductors is discussed, using the diagram technique for the evaluation of an appropriate two-particle temperature Green's function. The single-particle propagator for an electron moving in the impurity potential and simultaneously in interaction with the phonons is calculated and used. The interaction with the phonons is treated as weak. The line-shape function is found, and a comparison is made between this method of calculation and a previous one based on the decoupling of an infinite hierarchy of equations for double-time temperature-dependent Green's functions.
CORRUGATED-PLATE SPARK COUNTERS
Authors: Eichholz G. G. , Templeton W. M.
Published: April 2011

Stacks of corrugated plates with symmetrical parallel ridges have been employed as spark counters for the detection of alpha particles and neutrons. The counters were operated with various ridge pitches and plate spacings and with different counter gases. Such counters provide simple, rugged detectors with clearly localized corona discharges and are free from microphonics. When the grooves in the plates are filled with a hydrogenous or boron-containing material such counters function as low-sensitivity neutron detectors with negligible sensitivity to gamma radiation. Such detectors are promising for measurements of reactor neutrons.
NUCLEAR SPIN RELAXATION IN GASEOUS H2 AT LOW DENSITIES
Authors: Hardy Walter N.
Published: April 2011

The longitudinal and transverse nuclear relaxation times, T1 and T2, have been measured in normal H2 gas at 77.5 °K in the pressure range 0.05–2 atm. In this region T1 goes through a minimum, and T2 deviates significantly from a linear dependence on the density. Comparison of the experimental data with existing theory establishes the following results for the J = 1 state of ortho-hydrogen: (i) Autocorrelation functions of the molecular angular momentum operators are exponential or nearly so. (ii) The ratio of the correlation times τ1 and τ2 that are associated with operators of the form Jz and 3JZ2 − J(J + 1), respectively, lies within the limits [Formula: see text] (iii) The splitting of the molecular Zeeman levels cannot be neglected as in the original Schwinger theory.
ON THE THEORY OF WAVE PROPAGATION IN A BOUNDED COMPRESSIBLE PLASMA
Authors: Wait James R.
Published: April 2011

The influence of boundaries on wave propagation in a compressible plasma is considered. Although the models chosen are highly idealized, a number of interesting complexities arise that may be significant in actual bounded plasma configurations. For example, it is demonstrated that a perfectly conducting metallic boundary will support a surface wave in the plasma. However, if the boundary is not perfectly rigid, the surface wave will be attenuated even when the plasma is collisionless. Certain aspects of multiple reflections between two parallel boundaries are also treated in the paper.
MÉTHODE GÉNÉRALISÉE DE VARIATION. II
Authors: Fraga Serafín
Published: April 2011

not available
THEORY OF THE INTERACTION BETWEEN THE LATTICE VIBRATIONS AND THE ROTATIONAL MOTION IN SOLID HYDROGEN
Authors: Kranendonk J. Van , Sears V. F.
Published: April 2011

The effects of the interaction between the rotational motion of the molecules in solid hydrogen and the lattice vibrations, resulting from the anisotropic van der Waals forces, have been investigated theoretically. For the radial part of the anisotropic intermolecular potential an exp–6 model has been adopted. First, the effect of the lattice vibrations, and of the anistropic blowing up of the crystal by the zero-point lattice vibrations, is discussed. The effective anisotropic interaction resulting from averaging the instantaneous interaction over the lattice vibrations is calculated by assuming a Gaussian distribution for the modulation of the relative intermolecular separations by the lattice vibrations. Secondly, the displacement of the rotational levels due to the self-energy of the molecules in the lattice is calculated both classically and quantum mechanically, and the resulting shifts in the frequencies of the rotational transitions in solid hydrogen are given. Finally, the splitting of the rotational levels due to the anisotropy of the self-energy effect is calculated. The theory is applied to the calculation of the asymmetry of the S0(0) triplet in the rotational Raman spectrum of solid parahydrogen, and of the specific heat anomaly in solid hydrogen at low ortho-concentrations.
THE ABSORPTION SPECTRUM OF CNC
Authors: Merer A. J. , Travis D. N.
Published: April 2011

The ultraviolet absorption spectrum of the free CNC radical has been discovered in the flash photolysis of diazoacetonitrile, HC(CN)N2. The identity of the radical has been proved from isotopic evidence, using 15N and 13C, together with rotational analysis of the bands. Rotational analyses have shown that the bands of CNC must be assigned to two electronic transitions, A2Δu–X 2Πg, and [Formula: see text]. The sequence bands in the bending vibrations, which are observed in both electronic transitions, show evidence of Renner–Teller interaction in both the degenerate electronic states: this interaction is extremely large in the X2Πg state. The principal constants (in cm−1) of the observed states of CNC are as follows:[Formula: see text]The C—N bond length in the ground state of CNC is found to be 1.245 Å.CNC is isomeric with CCN, whose spectrum has been reported previously; some interesting comparisons are made between the spectra of these two molecules.
THE ELECTRON CAPTURE TO NEGATIVE ELECTRON EMISSION BRANCHING RATIO FOR 142Pr DECAY
Authors: Crocker I. H. , Werner R. D. , Cherrin W.
Published: April 2011

The ratio of electron capture to negative electron emission for the decay of [Formula: see text] has been found to be (1.64 ± 0.08) × 10−4. The half-life for electron capture, relative to the accepted beta emission half-life of 19.2 hours, is 13.3 ± 0.6 years. The ratio was found by mass-spectrometric stable isotope dilution determinations of the quantities of [Formula: see text] and [Formula: see text] produced by the decay.
SOME QUANTITATIVE CHARACTERISTICS OF THE SCHUMANN-ELF NATURAL ELECTROMAGNETIC BACKGROUND
Authors: Shand J. A.
Published: April 2011

Samples of Schumann-ELF natural background recorded in three components at widely separated points have been resolved, both by analogue and digital methods, into their constituent modes for quantitative comparison. ELF bursts display a world-wide coherence and uniform average signal strength to a high degree. Corresponding X and Y component traces are virtually identical at sites separated by 1 000 km or less. In contrast, among stations set in differing geological environments the strength of the vertical magnetic components of the same bursts may vary by orders of magnitude. No evidence of solar, auroral, or other nonlightning sources for natural ELF activity has been found.
ELECTRON COLLISION FREQUENCY IN NITRIC OXIDE
Authors: Mentzoni M. H. , Donohoe J.
Published: April 2011

The conductivity ratio, ρ, together with the electron radiation temperatures, Te, were measured in an NO afterglow, using a microwave wave-guide diagnostic method and noise sampling technique respectively. The normalized values of ρ are plotted versus Te in the electron radiation temperature interval 1 200–12 000 K° for pressures ranging from 0.25 to 4.0 Torr. Assuming the electrons to be Maxwellianized, the total collision frequency can be expressed as νc = N∙1.50 × 10−8u(eV)1/2 within the limits of accuracy of the experiment; however, the relation νc = N∙1.55 × 10−8u(eV)0.4 yields a closer fit to the mean of the experimental data. The electron thermalization is found to be nearly independent of pressure, indicating that metastable interactions may occur; some of these have been included in the discussion.
THE HALL AND SEEBECK EFFECTS IN NONSTOICHIOMETRIC BISMUTH TELLURIDE
Authors: Champness C. H. , Kipling A. L.
Published: April 2011

Detailed measurements of electrical conductivity (σ), Hall coefficient (RH), and Seebeck coefficient (α) were made on seven bismuth telluride samples of composition Bi2Te3+x, with x ranging from −0.06 to +0.48. Above room temperature the slope of RHT3/2 gave an apparent energy gap about 50% higher than that from the σ slope, and the Hall mobility decreased steeply with a T−4 dependence. These effects could be explained by an electron-to-hole mobility ratio (b) near unity, but the magnitude of α at higher temperatures appeared to require a b value of about 2. At the highest temperature the Hall mobility was found to increase with increasing tellurium content. The electron effective mass (mn) was found to be less than that of the holes (mp), at least below room temperature. Both mn and mp increased with extrinsic carrier concentration, and to some extent with temperature. These facts may be due to a stronger warping of the valence band at higher energies than the conduction band. The Hall mobility below room temperature could be explained by acoustic lattice scattering and degeneracy. At the Seebeck coefficient maxima, the value of αT was found to be roughly constant. The temperature slopes of α below the maxima were generally greater than expected classically. Anomalies were found in RH, RHσ, and α above room temperature in a near intrinsic n-type sample.
THE IONOLUMINESCENCE OF Zn2SiO4:Mn UNDER NEGATIVE AND MOLECULAR ION BOMBARDMENT
Authors: Wijngaarden A. van , Hastings L. , Koteles E. S.
Published: April 2011

A Zn2SiO4:Mn phosphor sample was bombarded by H+, H−, O−, O+, O2+, and O2− ions. In the energy range studied (10 < E < 90 keV), the ionoluminescence intensity was independent of the charge on the ion at the moment of impact. When the phosphor was bombarded by a molecular ion (H2, N2, O2, or CO2), the light output was less than the sum of the light outputs of the atomic constituents of the molecule at the same velocity.
THE COLLISION-INDUCED FUNDAMENTAL AND FIRST OVERTONE BANDS OF OXYGEN AND NITROGEN
Authors: Shapiro M. M. , Gush H. P.
Published: April 2011

The collision-induced rotation–vibration fundamental and first overtone bands of oxygen and nitrogen have been observed in the pure gas at pressures of a few atmospheres, and in mixtures of these gases with argon at pressures of a few tens of atmospheres. From the integrated intensities of the bands it is possible to deduce a value for the first derivative of the quadrupole moment with respect to internuclear distance; we find that |Q′| = 1.6ea0 for oxygen, and |Q′| = 0.95ea0 for nitrogen.
POLARIZATION CAPACITANCE OF DOPED POTASSIUM BROMIDE CRYSTALS
Authors: Wintle H. J. , Rolfe J.
Published: April 2011

Measurements have been made of the capacitance and conductance at 200 c.p.s. of a series of potassium bromide crystals doped with divalent anion and cation impurities. The dependence of the space-charge polarization capacity, caused by blocking of current carriers at the electrodes, on the conductivity and diffusion coefficient of carriers has been established. It is concluded that linearized theories of space-charge polarization cannot explain the experimental results.
COMPARISON OF HARMAN AND COOLING COUPLE METHODS FOR Z DETERMINATION
Authors: Muir W. B.
Published: April 2011

A Peltier–Seebeck or Harman type apparatus has been constructed to measure the Seebeclc coefficient, α, thermal conductivity, κ, electrical resistivity, ρ, and the figure of merit, Z, of thermoelectric materials over the range of temperature 150–300 °K while maintaining the sample in an approximately isothermal environment. Errors in the measured values of ρ, Z, α, and κ have been kept within 1, 1.5, 3, and 5% respectively. A comparison of the maximum temperature difference, ΔTmax, measured in a cooling test and the value of ΔTmax calculated from the values of α, κ, and ρ as a function of temperature measured in the Harman apparatus shows that, for five thermocouples, agreement is obtained within 1.2 °K on the average, with the greatest disparity being 2.5 °K.
ION-BOMBARDMENT-INDUCED RADIATION DAMAGE IN SOME CERAMICS AND IONIC CRYSTALS: DETERMINED BY ELECTRON DIFFRACTION AND GAS RELEASE MEASUREMENTS
Authors: Matzke Hj. , Whitton J. L.
Published: April 2011

Single-crystal specimens or polycrystalline sinters of cubic NaCl, KCl, KBr, KI, MgO, CaO, NiO, UC, CaF2, BaF2, UO2, and ThO2 as well as anisotropic TiO2, Al2O3, and U3O8 were bombarded with 40-keV xenon or krypton ions to give integrated ion doses of up to 2 × 1016 ions/cm2. The specimens were examined by reflection electron diffraction for radiation damage in the form of a phase change from the crystalline to a quasi-amorphous state (metamictization). Damage of this kind was observed in all anisotropic crystals; observable lattice disorder without phase change was obtained for MgO. None of the other cubic materials showed any appreciable change in their diffraction pattern, even at the highest dose. The annealing of the disorder in the lattice was correlated with release of the gas at low temperatures for all damaged substances. Significant gas releases at low temperatures were also obtained when much of the gas was in close proximity to the surface. Some other experimental conditions that cause gas release at low temperature are discussed.
EXPERIMENTAL EVIDENCE FOR THE DEFORMATION OF 128Ba
Authors: Pan P. J. , Horowitz Y. S. , Moore R. B. , Barton R.
Published: April 2011

The half-life of the 283-keV gamma transition in 128Ba has been shown to be less than (1.1 ± 0.2) × 10−10 sec, and its multipolarity has been shown to be E2. This E2 transition rate is enhanced by a factor of at least 58 over the single-particle estimates, indicating that the nucleus 128Ba is deformed at least to the extent β = 0.21.
LEAST-SQUARES FITTING OF A STRAIGHT LINE
Authors: York Derek
Published: April 2011

A detailed discussion of the calculation of the "best straight line" by the method of least squares is given. The most general solution is found and the conditions under which certain previously derived special solutions are valid are clearly stated. The "best" slope is shown to be given by the solution of the "Least-Squares Cubic". An example is given to illustrate the method. It is shown that the best slope is not necessarily bounded by values found from the regressions of x on y and y on x.
THE DECAY OVER LONG DISTANCES OF ROCKET-RELEASED LITHIUM DUE TO DIFFUSION, WINDS, AND CHEMICAL REACTIONS
Authors: Gault W. A. , Rundle H. N.
Published: April 2011

An enhancement of atmospheric lithium was observed over Saskatoon during March, 1965, following a rocket release of lithium at Churchill. A diffusion coefficient, an average wind velocity, and upper limits on certain lithium chemical reactions are calculated from the observations after certain assumptions are made. The horizontal diffusion coefficient, applicable over distances of 1 000 kilometers and times of weeks, is larger than diffusion coefficients over shorter distances and times. The vertical diffusion coefficient between 60 and 80 kilometers in height appears to be much lower than the large horizontal coefficients.
BETA–GAMMA ANGULAR CORRELATION IN 74As
Authors: Habib E. E. , Ogata H. , Armstrong W.
Published: April 2011

The A2 coefficient of the beta–gamma angular correlation for the cascade 2−(β+)2+(γ)0+ in the positron decay of 74As to 74Ge has been measured as a function of energy. The values found are 0.015 ± 0.006 at W = 1.8, 0.019 ± 0.004 at W = 2.0, 0.030 ± 0.005 at W = 2.1, and 0.025 ± 0.005 at W = 2.2, where the energy W is measured in mc2 units. The data have been used to examine the structure of the first excited level in 74Ge, using the "modified Bij approximation". Four shell-model configurations, as well as a rotational excitation, have been found to fit the experimental data. The validity of the application of the "modified Bij approximation" to this decay is discussed.