bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Electromagnetic Pulse Response of a Dipole Over a Plane Surface
Authors: Wait James R.
Published: October 2017

Using a surface impedance description, the electromagnetic fields of a vertical electric dipole are considered for a plane earth model. Particular attention is paid to the low-frequency region where the range to the observer may not be electrically large. The consequences in the time domain are also considered. Here, it is shown that the tail of the transient response is sensitive to the traditional low-frequency approximations that are usually accepted without question.
Search for High Energy Gamma Rays From the Sun
Authors: Kim C. Y.
Published: October 2017

An attempt to measure the flux of high energy solar gamma rays was made by comparing the angular distribution of the intensity from the direction of the sun and that of the intensity from the symmetrical direction about the zenith using two stacks of oriented nuclear emulsions flown by balloon on May 16, 1970, from Sioux Falls, South Dakota.

An upper limit to the flux of solar gamma rays was estimated to be 4.3 × 10−4 photons cm−2s−1 in the energy region above 10 MeV. On the day of the flight the sun was moderately active and the relative sun spot number was 161. Three importance-2 flares (2N, 2N, and 2B) and five importance-1 flares were reported during the period of the balloon flight.
A Space Correlation and Its Associated Turbulence Spectral Function
Authors: Samaddar S. N.
Published: October 2017

A space correlation associated with an isotropic turbulence spectral function is derived. A few special cases of this spectral function are also discussed. One of these special spectral functions was proposed previously for some valid physical grounds.
Far-Infrared Optical Absorption of Manganese Fluoride
Authors: Neimanis J. , Timusk T.
Published: October 2017

Optical absorption in MnF2 in the region from 50 to 350 cm−1 was studied. A search was made in particular for multiple-magnon processes previously reported in the literature. While, for example, four-magnon processes can be obtained theoretically from an expansion of the Heisenberg spin Hamiltonion, we found no temperature dependent absorption in the region studied other than the well-known two-magnon peak at 100 cm−1. All the observed peaks above 100 cm−1 could be attributed to phonons.
Electromagnetic Scattering of an Arbitrary Plane Wave by Two Nonintersecting Perpendicular Wire Grids
Authors: Hill D. A. , Wait J. R.
Published: October 2017

A doubly infinite set of linear equations is derived for the currents excited on the pair of planar wire grids by a plane wave of arbitrary polarization. The equations can be solved by perturbation if the two planar arrays are sufficiently separated or by truncation and matrix inversion otherwise. The transmission coefficients are derived including the cross-polarized components, and numerical results are presented to illustrate the effects of various parameters.
Matrix Elements for Many-Electron Atoms: Electrostatic Interaction Energies for One-Open-Shell Configurations
Authors: Karwowski J. , Fraga S.
Published: October 2017

The matrix elements of the electrostatic interaction have been determined and tabulated, in terms of Slater–Condon integrals or Racah parameters, for the states arising from pN, dN, fN, and gN configurations; in particular, the results for gN configurations have never been determined before. The effect of the interaction between states of the same symmetry and multiplicity, arising from a given configuration, is exemplified with numerical results for Pr, 4f36s2.
Molecular Correlation Functions in Liquid Carbon Disulfide and Carbon Diselenide
Authors: Suzuki Kenji , Egelstaff P. A.
Published: October 2017

Neutron diffraction structure factors for liquid carbon disulfide and liquid carbon diselenide have been measured and are analyzed to determine molecular correlation functions using the methods developed by Egelstaff, Page, and Powles. This analysis shows that the parallel molecular configuration is more probable in CSe2 than the T configuration expected from molecular quadrupole interactions. In CS2 the data are related to the carbon–carbon correlation function, which is shown to be similar to that for monatomic liquids.
Long-Range Potential Coefficients From RKR Turning Points: C6 and C8 for B(3ΠOu+)-State Cl2, Br2, and I2
Authors: Le Roy Robert J.
Published: October 2017

Methods of analyzing long-range RKR turning points to determine inverse-power potential coefficients have always required an implicit assumption about the relative magnitudes of higher-power coefficients. However, its effect on the derived constants has never been examined. A generalization of a method of Goscinski is introduced in which this assumption is explicitly introduced as the parameter α. Application of the new procedure to B-state Cl2, Br2, and I2 yields improved estimates of their C6 and C8 constants, but shows that such results may be strongly dependent on the assumed value of α. A search for an a priori estimate of α uncovered the intriguing empirical relationship (C10/C8)/(C8/C6) ≈ 4/3 between the theoretically known potential constants for a certain class of molecular states. However, its origin is not yet understood.
The Mixing Ratio of the (p3/2)−1 → (p1/2)−1 Transition in 15O
Authors: Kean D. C. , Wormald M. R.
Published: October 2017

The mixing ratio of the 3/2− → 1/2−, 6.18 → 0 MeV transition in 15O has been measured using the 14N(p,γγ)15O reaction. The value obtained is −0.141 ± 0.016, confirming previous indications that this mixing ratio is a factor of two larger than is predicted by shell-model calculations which give values consistent with experiment for the corresponding transition in 15N. The discrepancy may be due to uncertainties in the contributions to the E2 strength from the 16O core and to the effect of different thresholds for nucleon emission in the two nuclei. The analysis of the present experiment necessitated a reevaluation of available data regarding M2 strengths in the 1p shell.
Far-Field Potential of a Test Charge in an Inhomogeneous and Magnetized Plasma
Authors: Shukla P. K. , Spatschek K. H. , Yu M. Y.
Published: October 2017

It is shown that a stationary test charge in a magnetized inhomogeneous plasma has a far-field potential which falls off as the inverse cube of the distance between the test charge and an observer who is located in a direction perpendicular to both the density gradient and the external magnetic field. On the other hand, the effect of an external magnetic field parallel to the velocity of a slowly moving test charge in a homogeneous plasma is shown to be insignificant.
On the Kinetic Model Description of Rayleigh–Brillouin Scattering from Molecular Gases
Authors: Tenti G. , Boley C. D. , Desai Rashmi C.
Published: October 2017

We analyze in detail, in the kinetic regime, the behavior of a model kinetic equation previously used by us for the description of the density fluctuation spectrum in molecular gases. We find that over a small range of wavelengths and frequencies the predicted spectrum contains an unphysical feature, namely a shallow dip in the Rayleigh line. This effect is traced to the modelled elastic collision operator and has gone unnoticed in similar models of monatomic gases. We propose a modified model which corrects this feature and which appears to reproduce the details seen in light-scattering experiments.
A Study of Open Orbits in Lead Using the Induced Torque Technique
Authors: Bobier T. D. , Dixon A. E.
Published: October 2017

Open orbits in single crystal lead have been studied using the induced torque method. [Formula: see text]-directed open orbits were observed for all magnetic field directions in the {111} planes, except at the [Formula: see text] directions. Both [Formula: see text]- and [Formula: see text]-directed open orbits were observed for magnetic field directions over a range of 30 ± 1/2° centred on [110]. The torque, with the magnetic field along the [Formula: see text] singular field directions, approached zero. It was also observed that regions of aperiodic open orbits occurred for magnetic field directions within a cone of angle 20° ± 2° centred about the [Formula: see text] directions. The dependence of torque amplitude on both the open orbit direction relative to the sweep plane of the magnetic field and the magnetic field strength was also studied.
Positron Annihilation with Core Electrons in the Noble Metals
Authors: Becker E. H. , Gould A. G. , Senicki E. M. D. , Hogg B. G.
Published: October 2017

Experimental angular correlation curves for identically oriented single crystals of copper, silver, and gold have been obtained using "a point geometry" apparatus. The differences between these angular correlation data are compared to the differences predicted using a simple model of the Fermi surface combined with calculations of the theoretical core distributions.
The ν5 Fundamental Bands of N2H2 and N2D2
Authors: Carlotti M. , Johns J. W. C. , Trombetti A.
Published: October 2017

The infrared absorption spectrum of diimide (N2H2) in the 3.2 μm region has been reexamined at higher resolution than previously, and that of dideuterodiimide (N2D2) at 4.3 μm has been recorded for the first time. The ν5 fundamental (A- and B-type hybrid band) for both isotopic molecules has been analyzed, and a complete set of rotational and centrifugal distortion constants for the ground and ν5 = 1 states have been determined. The rotational constants of the ground states are (cm−1)

[Formula: see text]

and the following geometrical parameters were obtained for the planar trans-conformation of diimide :

[Formula: see text]

From the intensity alternation observed in the J structure of N2H2 spectrum, it is concluded that diimide has a totally symmetric ground state.
Evidence for Spin Isomerism from Proton Magnetic Resonance Studies of (NH4)2PtBr6 and (NH4)2PtCl6
Authors: Armstrong Robin L. , Driel Henry M. Van , Sharp Allan R.
Published: October 2017

Proton line shapes and spin–lattice relaxation times in the laboratory and rotating frames were determined in (NH4)2PtBr6 and (NH4)2PtCl6 over the temperature range 4.2 < T < 296 K. The data are discussed in terms of existing theories. It is clearly shown that a semiclassical model is not adequate to explain the observations. Further it is demonstrated that a satisfactory explanation of the data follows only if it is postulated that quantum-mechanical tunnelling and hence spin isomerism of the NH4 groups is important for these systems.
Experimental Investigation of the Imaging Properties of a Twisted Quadrupole Lens
Authors: Vermeulen F. E. , Chute F. S. , Youssef E. A.
Published: October 2017

A study is made of the imaging properties of an electrostatic quadrupole that has been uniformly twisted about its axis. Such a quadrupole has been built, and it is shown experimentally that the quadrupole identically reproduces the injection coordinates and momenta of a system of particles in a coordinate plane which is located some distance along the quadrupole axis. The experiments have been conducted using a beam of electrically charged micron sized dust particles.
On the Role of Nuclear Spin Symmetry of Symmetric Top Molecules in Gas Phase Nuclear Magnetic Relaxation
Authors: Sanctuary B. C.
Published: October 2017

For symmetric top molecules the role of nuclear spin symmetry is included in the derivation of the nuclear magnetic relaxation rate. It is assumed that this is dominated by a spin-rotation mechanism. Of the three nuclear spin species which exist for ZX3Y' symmetric tops, it is found that the "zero frequency" K = −1 to +1 term results in two of the species relaxing with a different rate from the third. The difference, which allows a direct NMR evaluation of the relative values of [Formula: see text] and [Formula: see text], is enhanced at low temperatures.
Low Frequency Noise in the Trap Free Insulated Diode with Thermal Free Carriers under Critical Condition
Authors: Sharma Y. K.
Published: October 2017

An analytical expression for the spectral intensity of low frequency noise voltage, based on the method of regional approximation, has been calculated for the trap free insulated diode containing thermal free carriers; while current is equal or greater than the critical value. It is shown that the value of noise in the potential minimum gives a very small contribution to the total noise.
Nuclear Structure of 63Ni by IAR
Authors: Ramavataram K. , Mercier G. F. , St-Pierre C. , Sykes D. , Yang C. S. , Ramavataram S.
Published: October 2017

The isobaric analogue resonances of the low excited states of 63Ni have been studied by bombarding targets of 62Ni with protons of energies between 2.5 and 5.0 MeV. Spins as well as the elastic and inelastic widths for some of these states have been determined. The spectroscopic factors that were deduced are compared with shell model predictions.
The Decay of 124Sb
Authors: Johnson J. R. , Mann K. C.
Published: October 2017

The gamma rays, beta rays, and conversion electrons emitted in the beta decay of 124Sb → 124Te have been observed using Ge(Li) and Si(Li) detectors both singly and in coincidence. The measured energies and intensities of the different transitions involved in this decay together with the coincidence results have allowed us to construct the decay scheme. The spin of most of the states and the parity of all of the states of 124Te populated in this decay have been deduced, some of them for the first time, and others as confirmations of previous assignments. We have also been able to assign collective parameters to many of these states, in terms of the vibrational model of nuclei, from the reduced branching ratios calculated from the gamma-ray intensities.
The Ground State of the One-Dimensional Ising Chain
Authors: Jennings B. K. , Bhaduri R. K.
Published: October 2017

We consider a linear spin 1/2 Ising chain with pair interactions extending up to the nth neighbor. The following general theorem is proved: 'The energy of any arbitrary spin sequence may be written as a linear sum of cluster energies, the upper limit of the number of Ising spins in a cluster being 2n'. The term cluster energy here is used to mean the energy of a group of spins in a certain configuration, evaluated as if the same configuration repeated itself throughout the chain.

The structure of the ground state of the system is investigated using the above theorem. It is shown that the ground state is a repetition of a certain cluster, and that the upper limit of the cluster size is 2n, except for some specific combinations of the interaction strengths when the ground state may admit mixing of different clusters.

The possible ground state configurations are worked out explicitly for n = 2, 3, and 4 in the absence of the magnetic field using the above theorem. Previous attempts were confined only up to n = 3.
Analysis of Ion Motion in Ion Cyclotron Resonance Cells
Authors: Knott Thomas F. , Riggin M.
Published: October 2017

The detailed discussion of ion motion in ion cyclotron resonance cells forms the basis of any interpretation of experimental results. We show that the resonance frequency of (quasi-) cyclotron motion is a function of the ion's position in the cell, and that its drift velocity exhibits a similar dependence. These features of the motion are due to the complicated multipole structure of the electric field. In spite of this, we find simple expressions for the ion coordinates as functions of time.
Theory of Ion Cyclotron Resonance
Authors: Bloom M. , Riggin M.
Published: October 2017

A theoretical analysis is given of the most commonly used type of ion cyclotron resonance (ICR) spectrometer, which has a cell of rectangular cross section. Though the equations of motion of the ions in this cell are extremely nonlinear, it has been possible to simplify the analysis by exploiting the facts that the longitudinal oscillations in the trapping potential are approximately decoupled from the cyclotron motion and that the cyclotron frequency [Formula: see text] the trapping oscillation frequency [Formula: see text] the spread of instantaneous cyclotron frequencies in the trap. A method is described for constructing an ensemble of ions appropriate to the mechanism of ion production and to the various drift and trapping voltages employed in the ICR cell. Line shapes are calculated in the collisionless regime. An ad hoc "average ion" model is presented, which simplifies the analysis of the spatial distribution of the ions through the dependence of the effective ICR frequency and line width on cell voltages and dimensions. Finally, an explicit distribution function is derived for the ion kinetic energy in the cell. The effect of a uniform RF electric field at resonance is shown to increase not only the average kinetic energy, but the spread of energies as well. A substantial spread of energies is also produced by the trapping oscillations. The breadth of the kinetic energy distribution complicates the interpretation of energy dependent processes using ICR under conditions normally used up to now. Some improved techniques for the study of energy dependent cross sections are proposed.
Dependence of Ion Cyclotron Resonance on Electrostatic Potentials
Authors: Riggin M. , Woods I. B.
Published: October 2017

The effect of the electron beam and electrostatic cell potentials on the spatial distribution of ions in a standard cyclotron resonance (ICR) cell is experimentally investigated. At low electron currents an "ad hoc" model of Bloom and Riggin accounting for the effect of the spatial distribution on the ICR line width and resonant field is found to describe adequately some of the complexities of the system. The influence of the distribution of initial ionic velocities on the ICR signal is also discussed and one alternate ion production technique is presented.
Line Shape in the 0001–1000 Band of Nitrous Oxide and Carbon Dioxide: Contribution of the "Hot Band" 0111–1110 to its Determination
Authors: Lacome Nelly
Published: October 2017

The deviation of line profile from Lorentz shape in the 0001–1000 band of nitrous oxide and carbon dioxide has been previously studied. Influence of the hot band 0111–1110 on the order of magnitude of this deviation is now pointed out and analyzed.
Significance of Branching Angles in Streamer Discharges
Authors: Nema R. S.
Published: October 2017

The phenomenon of branching at specific angles in streamer breakdown studies is found to be more universal than was ever thought. The angles measured in the breakdown of gases show that the coefficient of field distortion, K, lies in the range from 1 to less than 0.1. The values of K, so obtained agree well with those envisaged in the criterion of the streamer mechanism. It is hoped that branching angles observed in various types of breakdown may, possibly, be explained similarly.
Réalisation expérimentale de l'achromatisme d'un nouveau type de spectromètre de masse
Authors: Baril Marcel , Vallerand Pierre
Published: October 2017

This paper presents a brief examination of the optimum conditions for the use of an achromatic mass spectrometer consisting of a magnetic sector and a plane electrostatic mirror. The design of the apparatus is described. This spectrometer consists of two subassemblies for which the properties are calculated and measured independently. This apparatus permits the measurement of the chromatic effect of the plane electrostatic mirror and the achromatism of the system. The design of a new apparatus is also described which offers a useful compromise between high resolving power and the best energy bandwidth admissible into the spectrometer.
L Subshell Fluorescence Yields and Coster–Kronig Transition Rates at Z = 88 and 94
Authors: Campbell J. L. , McNelles L. A. , Geiger J. S. , Graham R. L. , Merritt J. S.
Published: October 2017

The L2 and L3 subshell fluorescence yields, ω2 and ω3, and the Coster–Kronig transition probability f23 in 88Ra and 94Pu have been deduced from conversion electron L X-ray coincidence measurements. The Chalk River [Formula: see text]-spectrometer was used to select the conversion electrons. X rays were detected in a Si(Li) counter which was calibrated for absolute X-ray detection efficiency. The results are as follows:

[Formula: see text]
Le spectre electronique de la molécule LuD
Authors: Effantin Christiane , D'Incan Jean
Published: October 2017

The electronic spectrum of LuD has been excited in a Lu2O3–Th–Cu hollow cathode filled with argon and traces of deuterium. All the recorded bands, lying in the visible region, belong to six electronic transitions towards the X1Σ+ fundamental state of the molecule. Molecular constants and symmetry properties of these states have been deduced from the vibrational and rotational analyses. The electronic isotope shift has been obtained from data of the H → X system. Finally, the anomalous intensities observed in the Δν = 2 sequences of the E → X and G → X systems are explained in terms of a mutual interaction between pairs of vibrational levels belonging to the E and G states.
Nuclear Mass Dependence of the Dirac–Breit–Pauli Hamiltonian
Authors: Karwowski Jacek , Fraga Serafin
Published: October 2017

The nuclear mass dependent (relativistic, specific, and normal) corrections for many electron atoms are discussed. Numerical values, determined from Hartree–Fock functions for all the neutral atoms from helium through nobelium, show that the relativistic mass correction, never included in actual calculations, is of the same order of magnitude as the specific mass effect.
An Attempt to Measure the Far Infrared Spectrum of the Cosmic Background Radiation
Authors: Gush H. P.
Published: October 2017

A liquid helium cooled two-beam far infrared interferometer has been successfully flown in a Black Brant III B rocket. The detector was a germanium bolometer cooled to a temperature of 0.37 K by a liquid He3 refrigerator. The sensitive range was between approximately 5 and 50 cm−1. Satisfactory cosmic spectra were not obtained because of contamination by radiation from the earth.
Inelastic Collisions Between Excited Alkali Atoms and Molecules X. Temperature Dependence of Cross Sections for 2P1/2↔2P3/2 Mixing in Cesium, Induced in Collisions with Deuterated Hydrogens, Ethanes, and Propanes
Authors: Walentynowicz E. , Phaneuf R. A. , Krause L.
Published: October 2017

The dependence on temperature of the cross sections for 2P1/2 ↔ 2P3/2 mixing in cesium, induced in collisions with various deuterated hydrogen, ethane and propane molecules, has been studied in the range 290–650 K. In the cases of hydrogen and ethane, the behavior of the cross sections was found to depend on the degree of deuteration of the molecules. The very large sizes of the mixing cross sections and the isotope effect observed in their variation with temperature, are ascribed to the phenomenon of electronic to rotational energy transfer.
Neutron Total Cross Sections Between 20 and 45 MeV
Authors: Bubb I. F. , Bunker S. N. , Jain M. , Leonard J. W. , McIlwain A. , Roulston K. I. , Standing K. G. , Wells D. O. , Whitmore B. G.
Published: October 2017

Neutron total cross sections have been measured in the energy range of 20 to 45 MeV for Be, C, Al, Cu, and Zn. The typical accuracy was 1% to 2%. Results are compared with optical model calculations in which the only variable is the surface absorption strength, which is constrained to vary with a linear energy dependence. The calculation is extended to include 13 nuclei with A < 75.
Anomalies in the Scattered Laser Light Spectra of a High Current Carbon Arc Plasma
Authors: Churchland M. T. , Nodwell R. A.
Published: October 2017

The scattered light spectra of a high current carbon arc plasma have been studied. The temperature and density of the arc column were mapped using conventional scattering techniques. Small enhancements in the scattered light spectra were found at several wavelength shifts, including the shift corresponding to the plasma frequency. The dispersion relation of the anomalous waves was studied as a function of the plasma parameters. A theoretical model was constructed with a dispersion relation similar to that observed experimentally.
On the Rapid Numerical Solution of the One-Dimensional Schrödinger Equation
Authors: Wills John G.
Published: October 2017

It is shown that the "new" method of rapid solution of the one-dimensional Schrödinger equation proposed by Newman and Thorson is equivalent to the well known phase–amplitude method.
Correlation Between the Anomalous Pressure Dependence of the Superconducting Transition Temperature in Thallium and the Temperature Dependence of its Knight Shift
Authors: Schratter J. , Williams D. Llewelyn
Published: October 2017

A study of the Knight shift has been carried out on a single crystal of thallium. The isotropic Knight shift decreases with increasing temperature, showing a nonlinear variation which is most pronounced between 50 and 150 K. This behavior is correlated with the anomalous pressure dependence of the superconducting transition temperature at low pressure. From the superconducting data on pure Tl and Tl–Hg alloys, we extract the volume dependence of the electronic density of states, and use it to derive the temperature dependence of the Knight shift. The results agree with the observed data.
Indirect Coupling Constants in a Thallium Single Crystal
Authors: Schratter J. , Williams D. Llewelyn
Published: October 2017

We have measured the angular dependence of the line width in thallium and related it to the second moment to estimate the pseudodipolar and pseudoexchange contributions for the first two shells of neighbors. These values are very different, despite the fact that both shells have nearly the same radius, and this establishes experimentally for the first time an orientation dependence of the indirect coupling constants.
Temperature Dependence of the Exchange Splitting in Ferromagnetic Metals II. The Study of Stoner Excitations by the de Haas–van Alphen Effect
Authors: Edwards D. M.
Published: October 2017

It is shown that the de Haas–van Alphen (dHvA) effect in ferromagnetic metals can give information about the Stoner T2 term in the temperature dependence of the magnetization, without interference from spin wave contributions. In particular, the temperature dependence of the dHvA frequency for a very weak itinerant electron ferromagnet could distinguish clearly between conflicting theories of these materials.
Neutron Scattering from Small Lead Particles
Authors: Novotny V. , Holden T. M. , Dolling G.
Published: October 2017

Neutron diffraction experiments on small particles of lead in the pores of Vycor glass are described. The small particles have a coherence length of (107 ± 20) Å; there is only a slight increase in the lattice parameter as compared with bulk lead, but an analysis of the intensity of the diffraction peaks reveals that there is an increase in the average amplitude of vibration of 28%. At least 80% of the lead in the glass is present in the crystalline state and contributes to the coherent diffraction.
Positron Trapping at Dislocations in Copper
Authors: McKee B. T. A. , Saimoto S. , Stewart A. T. , Stott M. J.
Published: October 2017

Measurements of positron lifetimes in cold worked copper samples show clearly positron trapping by dislocations. The copper crystals were deformed under conditions that would lead to known densities of dislocations in near random arrays and were annealed to remove other defects associated with the deformation. Using a trapping model, the data yields the value of μ = 2.9 × 1015 s−1 for the trapping rate per unit defect concentration, somewhat higher than the rate for trapping by vacancies in copper. The increase in lifetime of positrons trapped at dislocations is 34 ps (26%), about half the change for positrons trapped at vacancies in copper. A discussion of positron trapping at dislocations contrasted to vacancies emphasizes the differences arising from the extended nature of the dislocation. The theoretical picture leads to a trapping rate at dislocations roughly proportional to the binding energy.
Proton Spin Relaxation Study of Order Fluctuations above the Nematic–Isotropic Transition in the Liquid Crystal MBBA: I. Applicability of BPP Theory
Authors: Dong Ronald Y. , Wiszniewska M. , Tomchuk E. , Bock E.
Published: October 2017

The proton spin-lattice relaxation time T1 was used to study the short range orientational order fluctuations just above the nematic–isotropic transition in p-methoxy benzyli-dene p-n-butylaniline at 14, 11, and 4 MHz. This is made possible by calculating the contribution to the spin relaxation rate due to the molecular self-diffusion, which is known to be effective in relaxing the proton spins. The (T1)ef due to the critical order fluctuations at 4 MHz can be interpreted with the theory of de Gennes but not with the simple Bloembergen–Purcell–Pound theory.
Impact Problems for Nonhomogeneous Four Parameter Viscoelastic Rods
Authors: Moodie T. Bryant
Published: October 2017

Several impact problems for nonhomogeneous, four parameter, viscoelastic rods are studied: (i) an oscillatory stress is applied uniformly over the end of a semi-infinite rod, (ii) stresses in the form of Heaviside unit and Dirac delta functions are applied uniformly over the end of a semi-infinite rod, and (iii) the effect of an interface on waves generated by Heaviside impact of a semi-infinite, biviscoelastic rod is examined. In all cases, the rod is initially unstressed and at rest, and the propagation of one-dimensional, longitudinal waves is studied. Formal asymptotic expansions of the solutions are obtained. It is shown how Duhamel's theorem may be used to derive the solution for Dirac delta impact from that for Heaviside impact. For Heaviside impact of the biviscoelastic rod, it is found that reflected waves may be generated at the interface even though the impedance is continuous across it. For Heaviside impact of a rod whose properties satisfy definite functional relationships, the complete expansion is obtained.
Excitation of the 3s3p62S and 3s23p44s2P Levels of Ar+ and the 736 Å Line of Ne by Electrons
Authors: Tan K-H. , Donaldson F. G. , McConkey J. W.
Published: October 2017

Polarization free measurements are presented of the excitation of the 3s3p62S and 3s23p44s2P levels of Ar+ by electron impact. Line intensity measurements yielded relative transition probabilities in good agreement with the recent calculations of Luyken. A double peaked structure is demonstrated to be a common feature of the excitation functions and reasons for this are discussed. Cascade is shown to be an important excitation process for the 4s levels. Comparison is made with other work where available. As a means of calibration of some of the Ar line intensities, a careful measurement was made of the 736 Å Ne excitation function using the Bethe normalization procedure and the known optical oscillator strength.
Rotational Analysis of the lΠ–XlΣ+ System of C80Se
Authors: Stringat René , Bacci Jean-Paul , Pischedda Marie-Hélène
Published: October 2017

The strongly perturbed 1Π–X1Σ+ system of C80Se has been observed in the emission spectrum of a high frequency discharge through selenium and carbon traces in a neon atmosphere. The analysis of five bands yields, for the molecular constants of the ground state, the values Be″ = 0.5750 cm−1, [Formula: see text], αe″ = 0.00379 cm−1, re″ = 1.676 Å, ΔG″(1/2) = 1025.64 cm−1, and ΔG″(3/2) = 1015.92 cm−1. The numerous perturbations in the 1Π state prohibit the simple evaluation of the constants of the perturbed state and of the perturbing ones.
Collision Induced Microwave Absorption in N2, CH4, and N2–Ar, N2–CH4 Mixtures at 1.1 and 2.3 cm−1
Authors: Dagg I. R. , Reesor G. E. , Urbaniak J. L.
Published: October 2017

Collision induced microwave absorption is reported in pure N2, N2–Ar, N2–CH4, mixtures, and in pure CH4 in the 35 and 70 GHz regions (1.1 and 2.3 cm−1) at a temperature of 22 °C. The measurements are accomplished using overmoded high Q cavities capable of pressurization of up to 5000 p.s.i.g. The apparatus and method are described. With the high sensitivity attained, the results in pure N2 from 30 → 250 amagat reveal terms in the square and cube of the density from which the relaxation times are calculated. The linear dependence on frequency of the collision induced absorption up to 2.3 cm−1 is established. Higher order dependence on the density is observed in the N2–Ar and N2–CH4 mixtures. Various estimates of the quadrupole moment of N2 are given, making use of earlier results in other frequency regions.
Impact Parameter Representation for Forward and Backward Scattering of Two Particles
Authors: Allerton J. M. , Bhakar B. S.
Published: October 2017

The Lippman–Schwinger equation is solved to obtain an impact parameter representation for the forward and backward scattering. The Blankenbecler and Goldberger type amplitude is obtained in the high energy limit without any angular restriction. Then, the off energy shell amplitude in the forward and backward cone is obtained, which reduces to Glauber form on the energy shell. Finally, unitarity restriction and the scope of the formalism are discussed.
On the Vibration–Rotation Energy Transfer of Fast Rotating Molecules
Authors: Tam W. G.
Published: October 2017

A semiclassical theory of the vibration–rotation energy transfer of fast rotating molecules is presented. The formulation is based on the same model as that of Shin's classical theory. The semiclassical theory is simpler to derive and more rigorous. We show that it necessarily gives more accurate results than the classical theory. Applications to the systems HF and DF indicate that the two theories agree reasonably well in these cases.
Transport Properties of NbSe2
Authors: Huntley D. J. , Frindt R. F.
Published: October 2017

The Hall coefficient, magnetoresistance, and thermoelectric power of several specimens of NbSe2 have been measured as a function of temperature for various crystal orientations. A range of behaviour of the Hall coefficient has been observed varying from a reversal at 27 K for the purest specimen to no temperature dependence for the most impure. The magnetoresistance shows large deviations from Kohler's rule which are correlated with the Hall reversal. The results are discussed in terms of a possible phase change or a two-band model.
Proton Spin Relaxation in Low Density CH4–He Mixtures
Authors: Lalita Krovvidi
Published: October 2017

The spin lattice relaxation time T1 was measured in CH4–He mixtures at 298 K for two compositions in the density region where T1 goes through a minimum. The data were fitted taking the centrifugal distortion effects into account. The cross section for molecular reorientation due to CH4–He collisions was obtained.
Excitation par impact électronique des états 3s3p6nl de l'argon
Authors: Veillette Paul , Marchand Pierre
Published: October 2017

In the measurement of the photon emission intensity of argon excited by monoenergetic electron impact, as a function of the electron energy, several structures are detected between 24 and 28 eV. They can be attributed to excitation levels of the form 3s3p6nl and to negative ion resonances.
Fraunhofer Line Filling In (3855–1455 Å)
Authors: Harrison A. W. , Kendall D. J. W.
Published: October 2017

Noncoherent scattering of solar radiation, resulting in the filling-in of Fraunhofer lines, has been observed in the day sky spectrum from 3855 to 4455 Å. The filling in shows a continuous and almost constant effect over the wavelength range covered, although there is a tendency for the magnitude to decrease at shorter wavelengths. Observations taken over different terrains and at different times of the day and year show that the filling in tends to be higher for a high ground albedo in winter and for small solar zenith angles.
The Electrostatic Potential in a Finite Ionic Crystal: Orthorhombic Bravais Lattice
Authors: Redlack A. , Grindlay J.
Published: October 2017

Coefficients and polynomials describing the intrinsic potential in a finite ionic crystal are presented for the orthorhombic Bravais lattice.
Fast Neutron Capture in Tl, Hg, Au, and Ta and Gamma Ray Strength Functions
Authors: Earle E. D. , Lone M. A. , Bartholomew G. A. , McDonald W. J. , Bray K. H. , Moss G. A. , Neilson G. C.
Published: October 2017

Gamma ray spectra following the capture of 0.7, 1.7, and 2.6 MeV neutrons in Tl and Hg, of 0.7 and 2.6 MeV neutrons in Ta, and of 2.6 MeV neutrons in Au were measured with a NaI detector. The spectral distributions were obtained by unfolding the detector response function, and γ-ray strength functions were deduced for Tl, Au, and Ta by a spectrum fitting method. The strength functions in Tl and Au, when compared with the Lorentzian predictions, show a strong decrease below ~5 MeV and in Tl there is a resonance-like structure at ~5.5 MeV. No such structure is found in the strength function for Ta. This behavior is qualitatively interpreted in terms of recent particle–hole calculations.
Comments on Papers by Ryce et al. on The Electrostatic Dispersion of Liquids
Authors: Krohn V. E.
Published: October 2017

It is noted that all drops carrying more than one unit of electronic charge (on their surface) are either metastable or unstable and that the energetically most favored mode of binary fission does not result in daughter droplets with charges exceeding the Rayleigh limit, although this limit would be closely approached by the smaller daughter droplet if this mode of fission were induced in drops of low charge relative to the Rayleigh limit. Also, it is suggested that the secondary fission observed by Ryce and Patriarche probably followed a primary fission which was highly asymmetric because of perturbations existing when the original drop was created.
Diffusion of Slow Positrons from Gold
Authors: Pendyala S. , McGowan J. Wm.
Published: October 2017

An attempt has been made to experimentally determine the diffusion length LD of slow positrons (peak energy ~0.1 eV) in gold at room temperature by comparing the slow positron yield with phenomenological models for the yield. The diffusion of the slow positron is assumed to be similar to that of a thermal neutron diffusion in an absorbing and scattering medium. A collision mean free path of the slow positron in the electron gas under the Born approximation is estimated to be ~2 Å. This corresponds to a calculated value of the diffusion length LD ~250 Å. The experimental value is [Formula: see text].
Lifetimes of 7/2− States in 35Cl, 37Cl, and 39K
Authors: Hutcheon D. A. , White D. C. S. , McDonald W. J. , Neilson G. C.
Published: October 2017

Nuclear excited state lifetimes have been determined by direct timing, using a pulsed beam and a Ge(Li) detector in singles. Results are 35Cl (3163 keV), 46 ± 6 ps; 37Cl (3103 keV), 16 ± 9 ps; 39K (2813 keV), 71 ± 5 ps; 39K (3598 keV), 91 ± 27 ps. M2 and E3 transition strengths of the transitions in 35Cl and 37Cl are compared with previous theoretical calculations.
Flux Jumps in Nb3Sn Superconducting Ribbon
Authors: Harrison R. B. , Wright L. S.
Published: October 2017

A magneto-optical study of the flux jumping behavior of samples of vapor deposited Nb3Sn ribbons has been undertaken. Observations have confirmed that the magnetic stability of the superconductor is greatly enhanced by the addition of normal metal claddings; this is demonstrated with tracings taken from photographs which show directly the magnetic flux patterns in the samples.
Exact Analysis of a Spatially Nonequilibrium Knudsen Gas
Authors: Lee C. T.
Published: October 2017

The exact irreversible behavior of a gas of noninteracting particles bouncing elastically from the walls of a rectangular box is studied. The gas is spatially inhomogeneous at the beginning. The results indicate that a dynamic equation invariant under time inversion can give an irreversible solution. The general solution has been applied to the specific example of free expansion. Closed form analytic expressions for the evolution of the distributions of position, momentum, and temperature and for the change of entropy have been obtained. Based on the results of this problem, a more general view of the origin of irreversibility is presented.
Intensities of the Dipole and Quadrupole Rotation–Vibration Spectra of HD
Authors: McKellar A.R. W.
Published: October 2017

The 1–0, 2–0, 3–0, and 4–0 rotation–vibration bands of HD have been studied using a cooled multiple-traversal absorption cell and a grating spectrometer; intensities were measured for one electric quadrupole and 13 dipole transitions. There is particular interest in these intensities because HD has recently been detected on Jupiter by means of the 4–0 dipole band. Since the four bands were studied with the same gas samples and apparatus, possible errors in the measurement of their relative intensities were minimized. A rather large rotational dependence was found for the 1–0 band dipole transition moment. The present results are compared with theoretical intensity calculations, and it is concluded that there is good agreement for the quadrupole transition, but not for the dipole transitions.
K-Shell Autoionization in the Beta Decay of 204Tl
Authors: Ljubičić A. , Martel D. , Jones R. T. , Logan B. A.
Published: October 2017

The K-shell autoionization occurring in the β decay of 204Tl has been measured to be (1.18 ± 0.06) × 10−4 K-shell vacancies per emitted β particle. The result is in agreement with a recent theoretical prediction.
A Study of the Intermediate 5Li Ground State Produced in the 6Li(3He, αp)4He Reaction
Authors: Livesey D. L. , Piluso C. J.
Published: October 2017

An experiment has been performed on alpha–proton coincidences produced by the three body reaction 6Li(3He,αp)4He, at a bombarding energy of 1.25 MeV. Events ascribed to sequential breakup via the ground state of 5Li have been isolated with the aim of measuring the angular distribution of protons derived from 5Li. Difficulties are encountered because the alpha particle spectra in coincidence with the detected protons vary significantly with the proton angle. Possible interpretations of this effect are discussed. A tentative angular distribution, based on a compromise interpretation, shows a pronounced minimum which is shifted away from the 5Li recoil direction. Similar shifts have been detected in the 7Li(d,αn)4He reaction by Heggie and Martin, who explained the directional correlation effects in terms of a compound nucleus model. This model seems to be more applicable to these reactions than models based on stripping and pickup processes.
Analyse du Faisceau de Sortie d'un Laser Multimode
Authors: Bélanger P. A.
Published: October 2017

We present a theory that describes the transverse distribution of a multimode laser beam. The fundamental hypothesis of the theory is an equal partition of energy between each mode (hyperspheroïdal functions) of the resonator. It is shown that the theory is applicable for high gain lasers with large Fresnel numbers.
The Perturbation of Slowly Varying Electromagnetic Fields by Three-Dimensional Conducting Bodies
Authors: Jones F. W.
Published: October 2017

The perturbation of a slowly varying alternating field by conducting bodies of cubic shape is considered. A numerical method is used to determine the fields associated with the induced currents. Current concentrations are produced in the corners of the conductors, and these move inward and decay with time as the source field varies. A cavity region within the conductor further distorts the fields. A comparison is made with two-dimensional models.
Radiative Neutron Capture Study of 203TI
Authors: Colenbrander A. H. , Kennett T. J.
Published: October 2017

The results of a high sensitivity study of the 203Tl(n,γ)204Tl reaction are reported. Attention was focussed upon the detection of low intensity components and the establishment of the absolute intensity for the observed transitions. A technique for deconvolving the spectrum was employed which allows one to transform each spectral component into a simple Gaussian response and to thereby obtain a true representation of the gross spectral shape. The marked deviation of the spectrum from that expected using a simple statistical model is clearly revealed. The neutron separation energy was found to be 6655.8 ± 0.3 keV for 204Tl and 6503.4 ± 0.4 keV for 206Tl.
Light Diffraction Studies of CdS Phonon Masers: Polarization Effects
Authors: Vrba J. , Haering R. R.
Published: October 2017

We have studied polarization effects associated with the diffraction of light from ultrasonic waves present in c-axis phonon masers. Experimental data are presented and compared with a theory which assumes that the ordinary and extraordinary components of the light beam are diffracted coherently.
Wave Propagation in Inhomogeneous Elastic Media with (N + l)-Dimensional Spherical Symmetry
Authors: Clements D. L. , Rogers C.
Published: October 2017

Uniform loading of an (N + 1)-dimensional spherically symmetric inhomogeneous elastic solid is investigated. The governing equations are represented in a matrix form and reduction to the conventional wave equation is sought. Such reduction may be achieved for multiparameter forms of a certain function involving the density and elastic parameters of the material. The reduction to the wave equation allows certain initial/boundary value problems to be readily solved.
Some Aspects of Transverse Momentum Distributions of Particles Produced in High Energy Nucleon–Nucleus Interactions
Authors: Ahmad I. , Zafar M. , Irfan M. , Shafi M.
Published: October 2017

The pt distributions of pions, protons, deuterons, tritons, and 3He produced in interactions of 24 GeV/c protons with heavy emulsion nuclei have been experimentally investigated. The dependence of [Formula: see text] on the shower multiplicity, the angle of emission, and on the mass of the particles has been studied. The characteristics of pions have been observed to be similar to those produced in hadron–hadron interactions. It has been concluded that perhaps the pickup process is responsible for the production of heavier fragments and that most of the pions are produced in the first basic nucleon–nucleon collisions.
Finite Beta Drift Cyclotron Instabilities in an Inhomogeneous Plasma
Authors: Higuchi Yoshihiro
Published: October 2017

The effect of finite beta (the ratio of plasma kinetic pressure to magnetic field pressure) on drift cyclotron instabilities for the nonresonant and ion resonant modes are investigated through numerical analysis of their dispersion relations. For the nonresonant mode, it is found that the two unstable regions are merged into one unstable region, if the steep density gradient is decreased, and there is a new mode which has approximately ion cyclotron frequency due to the effect of finite beta. For ion resonant convective modes (kz ≠ 0), finite beta greatly reduces the instability growth rates, though it does not remove instabilities completely. Furthermore, the effects of magnetic field gradient and curvature are examined. It is found for the nonresonant mode that the maximum growth rates are slightly enhanced. For the ion resonant mode, they are slightly reduced and the wave number of the fastest growing wave is increased as the gradient and curvature drift velocity are decreased.
Theory of the Electron–Phonon Interaction
Authors: Moore R. A. , Perdew J. P. , Vosko S. H.
Published: October 2017

An exact solution to the self-consistent field screening problem is presented in terms of Bloch-state matrix elements of the bare perturbation. This solution is equivalent to one given by Sham and Ziman in terms of Fourier transforms of the bare perturbation, but unlike the latter it avoids the convergence problem in momentum space that arises in the screening of the electron–phonon interaction because of the 'deep' part of the ionic potential. The new form of the solution converts naturally into a pseudopotential formalism. At the same time it provides a framework in which to discuss and extend the two most common calculation schemes for the electron–phonon matrix element, the rigid Schrödinger potential model and the diffraction model. The inverse dielectric tensor is evaluated to first-order in the pseudopotential. Local field effects cause the Q → 0 limit of the electron–phonon interaction to deviate from its conventional value.