bluuebunny/crossref_metadata_2025 huggingface dataset:
Sequential-impact mass spectrometry; pressure dependence of ion currents from trapped-ion sources
Authors: Redhead P. A.
Published: April 2011

Positive ions can be trapped by electron space–charge fields in the ion-source of a mass spectrometer resulting in electron–ion collision sequences. With high electron current density (~0.5 A cm−2) and potential barriers to prevent ion escape along the axis of the electron beam, the trapping time can be increased sufficiently so that collision sequences with as many as 12 steps are observed.A simple model of the behavior of a trapped-ion source has been developed and solutions for the ion currents as a function of pressure obtained. The predictions of the model are compared with experimental results for neon and argon and approximate agreement obtained. Approximate values of cross sections for ionization and excitation of ions can be obtained by fitting the predictions of the model to the measured ion current vs. pressure curves.
New exact solutions of the Dirac equation
Authors: Lam Lui
Published: April 2011

Exact solutions of a Dirac electron in constant crossed electric and magnetic fields are found and given explicitly. The case of Klein–Gordon particles is shown to be a special case of ours.
Field dependence of carbon electrotransport in gamma iron
Authors: Falquero E. A. , Youdelis W. V.
Published: April 2011

The effect of field strength at constant temperature on the effective charge of carbon in gamma iron in electrotransport experiments is determined. At 950 °C the total effective charge is 4.5 for a field of 0.106 V cm−1, rising to a value of 13.6 at approximately 0.028 V cm−1, and falling rapidly at lower fields. Similar results are encountered at 920 and 980 °C; the temperature dependence of the total effective charge is not marked. It is proposed that carbon transport occurs by two processes: vacancy transport, which is activated by a field of approximately 0.028 V cm−1 but is field independent at higher fields, and interstitial transport, the rate of which is proportional to the applied field. The rate of vacancy transport is determined by an activation energy of 42 kcal/mole. The effective charge for purely interstitial carbon electrotransport is strongly temperature dependent; charge values of 2.5, 1.5, and 0.6 were obtained at 920, 950, and 980 °C respectively.
Afterglow gain measurements in CO2–He–N2 mixtures at pressures up to 1 atmosphere
Authors: Robinson A. M.
Published: April 2011

A CW 10.6 μm CO2 laser has been used to measure the small-signal gain as a function of time in transversely excited capacitive discharges in CO2–He–N2 mixtures at pressures up to 1 atm. The gain of the amplifier and the average gain coefficient were measured. Different gas mixtures were investigated and the general effect of N2 and He on the gain was observed. The gain invariably increased with reduction of pressure and amplifications of greater than six were measured in an amplifier length of 2.45 m. The gain increased with the voltage applied to the discharge condenser. Deflection of the laser beam by the discharge and the production of acoustic waves in the gas were attributed to gas heating.
Magnetic field perturbations in the magnetotail associated with polar magnetic substorms
Authors: Camidge F. Paul , Rostoker Gordon
Published: April 2011

Using data from the IMP-A and IMP-B satellites, it is shown that when a polar magnetic substorm onset is observed at the earth's surface, there is a pronounced effect in the magnetotail at approximately the same time. This magnetotail perturbation appears as a temporary reduction in the tail field reflecting primarily a reduction in the component of the field pointing along the sun–earth line parallel to the neutral sheet. Large perturbations in the component of the magnetic field perpendicular to the ecliptic plane which are observed around 24RE suggest that reconnection of magnetic field lines is the physical mechanism responsible for the observed effects. It is suggested that substorms act as a safety valve limiting the size of the magnetotail by periodically bleeding magnetic flux from the tail into the inner dipole configuration.
Studies of the ionic ferromagnet (LaPb)MnO3. V. Electric transport and ferromagnetic properties
Authors: Searle C. W. , Wang S. T.
Published: April 2011

Resistivity and magnetoresistance data obtained from 77 to 700 °K are presented. These data suggest an interpretation based on a strongly spin-polarized conduction band. A model is developed based on this interpretation which can consistently describe the present data and previously published data.
Measurements of the shape of ionospheric irregularities using satellite transmissions
Authors: Dixon A. F. , Forsyth P. A.
Published: April 2011

Amplitude and phase scintillations were observed in the radio signals propagated at a frequency of 40 MHz from a satellite to two stations on the ground separated by a distance of about 10 km. By comparison of the signal fluctuations at the two stations the size and shape of F-region ionospheric irregularities were deduced. The lengths of irregularities oriented along the magnetic field ranged from 3 to 30 km with axial ratios of 11 to 60.
Gauge invariance and the charge operator in the Heisenberg picture
Authors: Pugh Robert E.
Published: April 2011

The transformations of the renormalized interpolating fields generated by the gauge transformation of the free asymptotic fields restrict the interpolating fields to satisfying certain commutation rules. These commutation rules, in turn, give a non-phenomenological charge operator for the interpolating Heisenberg fields. Redundant states and the eigenvalue problem with the indefinite metric are discussed.
Hall effect and anisotropic relaxation times in α-phase AgCd, AgIn, AgSn, and AgSb alloys
Authors: Alderson J. E. A. , Hurd C. M.
Published: April 2011

The Hall resistivities of polycrystalline samples of the series Ag(Cd → Sb) have been measured in the temperature range 4.2–80 °K, and in the field range 2–15.17 kG. The solute concentration ranges between 273 and 6715 atomic p.p.m. Special consideration was given to the establishment of the low-field condition, for which the negative Hall coefficients of the Ag(Cd → Sb) series at 4.2 °K are found to be 9.49, 9.59, 9.67, and 9.77 × 10−11 m3 A−1 s−1 respectively, with an accuracy of ± 0.04 in these units. Using the model of Dugdale and Firth, the corresponding values of the ratio τN/τB are 0.64, 0.57, 0.52, and 0.47 respectively. It is shown that there is qualitative agreement between the dependence of τN/τB upon solute valence and that expected from the known electronic structure of the solutes. The paper also includes results for the field dependence of the transverse magnetoresistance shown by the samples at 4.2 °K, which have been used to establish the low-field condition.
Collisional narrowing of the vibrational Raman band of nitrogen and carbon monoxide
Authors: May A. D. , Stryland J. C. , Varghese G.
Published: April 2011

Observations of the pressure narrowing of the vibrational Raman bands in N2 and CO are presented. For both gases a pressure of about 200 atm reduces the half-width of the bands by a factor 2. This behavior is explained in a semiquantitative way by the theory of motional narrowing. Motional narrowing occurs when the frequency of rotationally inelastic collisions reaches the magnitude of the frequency separation of the individual band components.
Superconducting magnet suspension systems—persistent mode operation
Authors: Atherton David L.
Published: April 2011

The lift force generated by a rectangular superconducting magnet operating in the constant flux (persistent mode) and moving over an infinite conducting plane is derived from the lift equation for such a magnet operating in a constant current mode.
A charged particle Stern–Gerlach experiment
Authors: Enga Eric , Bloom Myer
Published: April 2011

It is shown that a charged particle Stern–Gerlach experiment can be performed in a magnetic field geometry which is similar to that used in accelerators of the strong-focusing type. In particular, we analyze the helical quadrupole system. The analysis is based on an extension of the theory of the transverse Stern–Gerlach experiment to time-independent, inhomogeneous magnetic fields. The effect of the Lorentz force is reduced by using orthogonal inhomogeneous electric fields.
Application des miroirs électrostatiques à l'élimination de l'effet chromatique dans les spectromètres magnétiques. Deuxième partie: les aberrations
Authors: Baril Marcel
Published: April 2011

In the first part of this series, the first-order theory for the correction of the chromatic effect in magnetic spectrometers by an electrostatic mirror was given. In this second part, aberrations are studied. It is shown that in many cases at least two main aberration terms could be eliminated. Resolving powers have been discussed and calculated, including intensity distribution and valley-over-peak ratio effects.
Growth of liquid droplets in metastable Van der Waals vapor
Authors: Strickfaden W. B. , Sobrino Luis de
Published: April 2011

The growth of liquid droplets in metastable vapor is studied by means of a microscopic model for a nonequilibrium Van der Waals gas. Results showing the initial growth of very small droplets (~20 Å) are given. The results are in qualitative agreement with the behavior to be expected on the basis of our experimental knowledge of the phenomenon of condensation.
Veiling glare due to multiple reflections between surfaces
Authors: Naylor Antony G.
Published: April 2011

The intensity of the veiling glare due to multiple reflections between optical surfaces of an optical instrument was determined using a ray trace method. It is shown that the increase in the ratio veiling glare to real image intensity for decreasing apertures is due mainly to the difference in the entrance pupils of the main and reflected beams, and not to the increase in diffraction; also that the internal reflection within a lens causes significant contributions to the veiling glare for bright off-axis objects which are out of the normal field of view. The veiling glare intensity patterns are shown for an on-axis object for a Cook triplet using various apertures.
Magnetic circular dichroism and moments for A2 → E transition in C3ν defect centers
Authors: Sati R. , Inoue M. , Wang S.
Published: April 2011

The spectral line shape of the magnetic circular dichroism (MCD) for the A2 → E transition is investigated. The dynamic Jahn–Teller effect is taken into account by two different methods, i.e. (i) in Franck–Condon and adiabatic approximation and (ii) method of moments. The line-shape function for the magnetic circular dichroism is calculated without using the rigid shift approximation. A comparison of this line shape with the one obtained in the rigid shift shows the two line shapes to be different. General closed expression for the nth order moment is obtained, in the absence and the presence of an externally applied magnetic field, by making use of (i). Zeroth-, first-, and second-order and the change in the third-order moments have been obtained using (ii). The moments up to the second order and the change in the third-order moment have the same expressions as obtained by (i) and (ii). The MCD line shape and the different order moments have also been obtained for the 3A2 → 3E electronic transition in the R′ center.
Electrodynamics of strong-coupling superconducting alloys in high magnetic fields
Authors: Usadel Klaus D.
Published: April 2011

The electromagnetic response of superconducting alloys in the electron–phonon model is investigated for situations where the electric field is parallel to the static magnetic field. It is shown that for ordinary microwave frequencies strong-coupling only renormalizes physical quantities, but does not change the form of the weak-coupling response function.
Localized canting model for substituted ferrimagnets. II. Doubly substituted YIG systems
Authors: Rosencwaig A.
Published: April 2011

The localized canting model has been extended to the doubly substituted YIG systems. Canting criteria have been developed which indicate the possibility for localized canting in both sublattices for some of these systems. Application of this model to a doubly substituted YIG system with a known cation distribution has resulted in a determination for YIG of Jdd/Jad ~ 0.22 and Jaa/Jad ~ 0.07 in close agreement with the results obtained in Part I. The localized canting model has also been used to establish the cation distribution for various doubly substituted YIG systems. In particular, this model has been applied to the AI- and Ga-substituted YIG's providing interesting information about the magnetic structures of these systems.
Radio-frequency heating of a plasma
Authors: Cross R. C.
Published: April 2011

If a uniform plasma is surrounded by a heating coil in the presence of a steady axial magnetic field, it is shown that a considerable increase in power absorption may be expected if the operating frequency is chosen to be close to a magneto-acoustic resonance of the plasma column. This effect is due to a very large increase in the oscillating field at the center of the plasma column. For an initially cool plasma, heating is due to a combination of ohmic and collisional heating, while at higher temperatures, collisional heating by magnetic pumping is the dominant heating mechanism.
Infrared absorption due to H− ions in sodium and potassium halides. II. Impurity induced absorption in the far-infrared region
Authors: MacPherson R. W. , Timusk T.
Published: April 2011

Measurements and calculations of the impurity induced far-infrared absorption due to H− ions in the sodium and potassium halides are presented. The defect model which was previously determined from theoretical fits to experimental local mode and anharmonic side band data is used to predict the absorption spectrum in the far-infrared region below the reststrahlen frequency. The agreement with the observed absorption spectra is good. It is shown that certain features may be interpreted as Van Hove singularities in the unperturbed density of states of the host crystals and that other peaks in the KBr and KI spectra are due to localized resonances.
Amplitude-dependent and thermally activated mechanisms for extended dislocations
Authors: Blair D. G. , Hutchison T. S. , Rogers D. H.
Published: April 2011

This paper examines the general problem in which a system "jumps" between two potential wells. The conditions governing the "rate equation" are applied to a model in which an extended dislocation jumps about a pinning agent. The environment seen by the model under a cyclic stress of amplitude σ0 and at temperature T can be represented by a point (σ0, T) on an activation diagram. Regions of different behavior of the model can also be represented on the diagram.
Coherence transfer between the 2P1/2 and 2P3/2 states in sodium, induced in collisions with helium atoms
Authors: Elbel M. , Niewitecka B. , Krause L.
Published: April 2011

The Hanle effect, which is commonly exhibited by atoms that emit resonance fluorescence while in a magnetic field, has been observed in sensitized fluorescence of sodium vapor. The sodium atoms were excited by σ+ polarized D1 radiation which produced a vector polarization in the 32P1/2 state, and were then transferred to the 32P3/2 state by collisions with helium atoms. The fluorescence was observed at an angle of 325° to the direction of excitation, and the magnetic field was perpendicular to the directions of the exciting and fluorescent light beams. The addition of helium resulted in the appearance of a circularly polarized D2 component in the fluorescent light. The polarization of the sensitized fluorescence decreased with increasing field as in the ordinary Hanle effect but the width of the Hanle signal was smaller than that observed in resonance fluorescence. The observed narrowing effect is in good agreement with theoretical predictions.
Collisional depolarization of light alkali atoms excited to their lowest 2P levels
Authors: Elbel M.
Published: April 2011

Transition matrix elements connecting the Zeeman sublevels of the lowest p doublets in light alkali atoms have been derived using methods of steady-state collision theory. The matrix elements generally consist of two parts which, under rotations of the quantization axis with respect to the scattering plane, behave like components of a first rank and a second rank tensor, respectively. Only the second rank tensor components lead to the selection rule j, mJ↔j, −mj, whereas the first rank tensor components do not. The latter can be ascribed to a formal interaction term which is proportional to the inner product of the orbital angular momenta of the valence electron and the colliding atoms, respectively, thus accounting for molecular coupling phenomena during the collision. Finally, the transition matrix elements are used to calculate the depolarizing cross sections from the van der Waals potential.
Experimental Determination of Changes in the Fermi Surface of Metallic Tin Produced by Uniaxial Tension
Authors: Perz J. M. , Hum R. H.
Published: April 2011

The effects of tension on seven extremal areas normal to [001] in white tin have been studied by measuring the changes in phase of de Haas van Alphen oscillations. All areas have been found to depend linearly on stress over the whole range of tension used, which corresponded to a maximum fractional volume increase of 0.5 × 10−4.
Body Force Density in the Elastic Dielectric
Authors: Grindlay J. , Redlack A.
Published: April 2011

The laws of conservation of linear and angular momentum are shown to impose certain integral conditions on the body force density in an elastic dielectric which is in static equilibrium.An equation of state, quadratic in the variables Di, Di;j, Ei, Ei;j, is postulated for the body force density. In the case of nonpiezoelectric cubic material symmetry it is found that, within the quadratic approximation, the integral condition imposed by the law of conservation of linear momentum is satisfied only if the body force of this form vanishes.
Scattering from a Particular Class of Conducting Corrugated Cylinders
Authors: Shafai Lotfollah , Tse Stanley S. H.
Published: April 2011

The electrostatic equipotential surfaces of n identical strips intersecting azimuthally along an axis constitute the surfaces of certain corrugated cylinders. The cross sectional geometry of the corrugations varies from the limiting form of the intersecting strips to a circular cylinder at large distances from the intersecting axis. The problem of two-dimensional scattering of electromagnetic waves by these geometries is considered and numerical solutions are found by using two separate methods—a matrix formulation and an integral equation method. The special case of four intersecting strips illuminated by plane electromagnetic waves polarized parallel to the intersecting axis is considered in detail and the numerical results for the surface currents and the scattered fields are evaluated.
On the Existence of Wave Operators in Time-Dependent Potential Scattering for Long-Range Potentials
Authors: Manoukian E. B. , Prugovečki E.
Published: April 2011

The existence of physical asymptotic states and wave operators is derived for potentials which for r → ∞ decrease faster than r−α for some α > 1/2 and α > 3/4, respectively.
Rotational Invariance in the Centrifugal Stretching of Deformed Nuclei
Authors: Trainor L. E. H. , Gupta Raj K.
Published: April 2011

An explicit model is developed for the rotational and quasi-rotational states of heavy deformed nuclei. It is assumed that the effective mass contributing to the rotational inertia lies outside a central, geometric core which is rotationally invariant. The effective mass is modified as a result of nuclear stretching which is assumed to take place against harmonic restoring forces. Good agreement with experiment is obtained for the so-called hard rotators and even for the neutron deficit and transition nuclei. Explicit expansions are obtained for the energy spectra and the effective moments of inertia in the form of asymptotic series in the angular momentum variable. These series give better convergence for low angular momenta and hard rotators.
High Current Density Superconducting Magnets Using Heavy Currents
Authors: Atherton D. L.
Published: April 2011

This note reports on three 5 cm inside diameter superconducting magnets generating 66 kG at 1250 A, 64 kG at 1360 A, and 56 kG at 1890 A, with current densities of 27 200 A/cm2, 30 500 A/cm2, and 42 000 A/cm2, respectively. Fine filamentary conductors are used. Charge rate sensitivity is reported.
Confirmation of the Existence of a 2044.1 keV State in 102Ru
Authors: Taylor H. W. , Singh B.
Published: April 2011

The primary transitions deexciting a 2044.1 keV level in 102Ru proposed earlier have been observed in singles and coincidence spectra, confirming the existence of the level. From a comparison of the population and decay modes of this state with those of the nearby 2+ state at 2037.5 keV, the spin–parity of the 2044.1 keV state is inferred to be 3−.
Scattering and Tunneling of Electronic Excitations in the Intermediate State of Superconductors
Authors: Demers Jacques , Griffin Allan
Published: April 2011

We give a systematic discussion of the anomalous scattering of Bogoliubov excitations at sharp N–S and S–N boundaries as well as quasi-particle tunneling in N–S–N and S–N–S geometries. The relation between the transmission resonances (E > Δ) and the bound states (E < Δ) in N–S–N and S–N–S geometries is explicitly exhibited. We also work out the extra thermal resistance due to scattering by a normal layer imbedded in a superconductor and by a superconducting layer imbedded in a normal metal, with results different from that obtained by Shikin.
Electron Spin Resonance of Gd in Mg Metal
Authors: Ehara Shaw
Published: April 2011

ESR of Gd in dilute Mg(Gd) has been studied by Das et al. in order to understand the resistance anomaly observed in this alloy. A value for g = 2.03 ± 0.005 has been obtained for ESR of Gd in Mg(Gd).The positive s–f exchange interaction indicated in our ESR experiment accords with the sign of s–f exchange interaction obtained from the resistance curve according to Kondo's theory. At the lowest temperature the magnetic ordering in this alloy is suggested.
Padé Approximant Calculation of p-Wave π–π Scattering with a σ Model Lagrangian
Authors: Elias D. K.
Published: April 2011

A π–π it interaction via a scalar I = 0, σ exchange is considered. The contribution of the t and u channel exchanges of the σ to the p-wave, I = 1 amplitude is calculated using Padé approximants. A p-wave resonance, interpreted as the p meson, the width of which depends on the mass of the input a meson, is found; for a certain range of values of the σ mass the ρ width compares not unfavorably with similar calculations using a [Formula: see text] interaction. However, for the range of masses considered the width is considerably smaller than the experimental value. The I = 0, d-wave channel is also considered and a resonance, interpreted as the ƒ0(1260), is found.
Heating of the Electron Component of Magnetoplasma by Magnetic Perturbations
Authors: Shukla P. K. , Singh R. P. , Singh R. N.
Published: April 2011

The Boltzmann transport equation has been solved for the change in the assumed Maxwellian distribution of electron velocity in response to certain magnetic perturbations. The heating of the electron component of the fully ionized and weakly ionized magnetoplasma has been studied. The effect of propagating and localized magnetic perturbations has been considered. Electron heating has been estimated for certain adopted magnetic perturbation and magnetoplasma parameters. The feasibility of devising a laboratory experiment for electron heating has been argued.
Nonlinear Damping of Longitudinal Ion Modes
Authors: Pocobelli Gustavo
Published: April 2011

The nonlinear damping rate of an ion mode in an infinite, homogeneous plasma is calculated for [Formula: see text] by means of the Vlasov–Poisson system (Te and T1 indicate the electron and ion temperature, respectively). It is found that after the well-known linear stage [[Formula: see text], τe ≡ (m/eAk)1/2; A ≡ amplitude of the mode at t = 0], a nonlinear-electron linear-ion stage sets in [[Formula: see text], τ1 ≡ (M/eAk)1/2], during which the electron contribution to the damping rate diminishes substantially. The ions still give a linear contribution. Eventually, in the nonlinear ion stage [Formula: see text] the damping rate of the mode phase-mixes to zero.
High Resolution Study of the Energy Levels of 27Al
Authors: Doekes C. , Kean D. C. , Elliott R. V. , Spear R. H.
Published: April 2011

The energy levels of the nucleus 27Al have been studied with an energy resolution of about 6 keV by magnetic analysis of the protons from the 27Al(p, p′)27Al reaction. A number of previously unreported levels have been observed.
Approximate Analytic Eigenvalues of Lennard–Jones Potentials
Authors: Eu Byung Chan , Guerin Herve
Published: April 2011

Approximate analytic expressions of eigenvalues for Lennard–Jones (10,6) and (12,6) potentials are obtained. The eigenvalues obtained from such expressions are compared with the WKB or numerical eigenvalues for the estimation of accuracy.
A 4He Discharge Light Source and Optical System for the Optical Pumping of 23S13He
Authors: Daniels J. M. , Timsit R. S. , May A. D. , Yuen Virginia L. S.
Published: April 2011

Details are given of the construction and performance of a 4He discharge lamp and optical system for optical pumping of 23S13He. The lamp is made of fused quartz and is water cooled. It is excited by 160 MHz radio-frequency power applied to internal electrodes. The first part of the light gathering system is built into the lamp as an integral part of the cooling jacket. For a radio-frequency input of 600 W, 1.4 × 1017 circularly polarized photons s−1 are delivered in a cone of half angle 30° to the specimen to be optically pumped. The width of the 1.083 μ line emitted is about 0.087 cm−1. This lamp has behaved satisfactorily during extensive life tests.
The Expected Performance of an Optical Pumping Light Source, and the Kinetics of Optical Pumping of 23S13He
Authors: Daniels J. M. , Timsit R. S.
Published: April 2011

A practical light source for optical pumping necessarily excites transitions other than those which it is desired should be excited. It is shown that a pumping light source for 23S13He may be characterized by three parameters, which describe the transition rates for Δm = ±1, and 0, transitions under standard conditions. Expressions are derived relating these parameters to the geometry of the light source. The equation which describes the flow of angular momentum into 3He is formulated, using these parameters, the light flux, the lifetime of the metastable atoms, and collisional mixing in the 23P states. This equation is solved to give the polarization which may be attained, and the rate at which the polarization is built up. A modification of this equation is also given, which takes into account moderate trapping of resonance radiation. An expression is also derived which relates the polarization of 3He to the intensity of the scattered pumping light.
Nuclear Relaxation of 3He Gas on Various Solid Surfaces
Authors: Timsit R. S. , Daniels J. M. , May A. D.
Published: April 2011

The nuclear spin–lattice relaxation time of 3He gas in contact with metallic and glass surfaces has been measured. The relaxation time of the gas in the presence of a glass surface is strongly dependent on both the permeability of the glass to helium and the concentration of paramagnetic impurities in the glass. Two relaxation mechanisms may in this case be distinguished, relaxation due to the diffusion of the gas into the glass and relaxation induced during the adsorption of the helium on the glass surface. A phenomenological model to account for these observations is proposed.The mechanism responsible for the relaxation of 3He on metallic surfaces remains obscure.
A Large Volume Homogeneous Low Field Electromagnet
Authors: Daniels J. M. , Kiang A. K. C. , Kirkby P.
Published: April 2011

An electromagnet is described which generates low fields, typically 10 G, that are homogeneous over a large volume. The magnet is constructed of 12 coils lying on the surface of a sphere 1 m in diameter, and 18 coils lying on the surface of a concentric sphere 1.5 m in diameter. Both the measured and calculated field gradients show that (∂H/∂z)/H < 10−3 cm−1 for distances of 20 cm from the common center of the spheres along the common axis. Measured field gradients across the equator show that (∂H/∂x)/H and (∂H/∂y)/H < 2 × 10−4 cm−1 for distances of 30 cm from the common center. The currents in the coils on the outer sphere are in opposition to those in the coils on the inner sphere, in order to cancel the external magnetic field. This feature allows the magnet to be placed inside a close fitting magnetic shield, without interaction between the magnet and the shield. Design formulas, constructional details, and tests on the completed magnet are given.
Charge Equilibrium Fractions and Charge-Exchange Cross Sections for Fast Ions in Nitrogen and Argon
Authors: Ormrod J. H. , Michel W. L.
Published: April 2011

Charge equilibrium fractions and charge-exchange cross sections have been measured in nitrogen and argon targets for ions with Z ≤ 11 and energies 20–80 keV. A lower bound to the stopping by charge exchange was calculated using these measurements. At constant velocity, this calculated minimum rate of energy loss from charge-changing collisions varies with atomic number in the same periodic manner as the electronic stopping cross sections and the charge-exchange contribution may account for most of the variation.
The A.C. Josephson Effect in Nb–Hg Contacts
Authors: Angadi M. A. , Graham G. M.
Published: April 2011

Some experiments with Nb–Hg contacts are described which suggest that these may be the basis of practical microwave systems.
Theory of Damping due to Thermally Assisted Unpinning of Dislocations
Authors: Blair D. G. , Hutchison T. S. , Rogers D. H.
Published: April 2011

By algebraic methods, this paper obtains expressions for the decrement and modulus defect due to the breakaway of a dislocation from a row of equally spaced pinning points, using expressions for the activation energy given in an earlier paper. The model is that of Teutonico, Granato, and Lücke, but incorporating a pinning force of general shape. The plane, representing the complete range of values of temperature T and stress amplitude σ0, is found to consist of five regions (A to E) of qualitatively different behavior. In regions B, C, and D, breakaway (from the whole row) is activated at a single pin, as in the Granato–Lücke model; in A and E, breakaway is activated over a group of several pins. In A and B, few of the dislocations break away during a stress cycle; in C and E, nearly all do. As one moves from the "few-all" boundary into a "few" region (A or B) by decreasing T or σ0, the decrement decreases rapidly in an exponential fashion. As one moves into an "all" region (C or E), it decreases, but not rapidly. For [Formula: see text] (short loops), only two regions, A and E, exist; here, β = LcU0/Cr2, where Lc is the distance between pins, U0 is the maximum binding energy between a dislocation and a pin, C is the tension of the dislocation, and the pinning force has its maximum at a displacement of order r, the "range". Region D differs from the other regions in that there the activation energy for unpinning remains effectively constant during the cycle; the theoretical damping peak of Koiwa and Hasiguti lies in D. Region D exists only when [Formula: see text] (very long loops); here, νt is the effective attack frequency for unpinning, ω is the angular frequency of the applied stress, and the pinning force varies as y−γ−1 at large displacements y. The peak decrement, which is constant along the "few-all" boundary except near region D, drops by a factor of 2.5 when D is entered. All the boundaries between the five regions are obtained. Within each region, expressions for the decrement and modulus defect are given, which are accurate at least in limiting cases; stresses near the mechanical breakaway stress are also discussed. Generalized forms of these expressions are also given, applying to a class of damping mechanisms possessing symmetry of the breakaway type. The theory is related to experimental results of Hutchison and Rogers, and Koiwa and Hasiguti.
Beta Decay of 35Ar
Authors: Geiger J. S. , Hooton B. W.
Published: April 2011

The gamma radiations from the decay of 35Ar have been studied using Ge(Li) γ-ray detectors. Evidence is found for previously unreported β feeds to the 35Cl levels at 2695 and 3003 keV. The percentage β feeds to 35Cl levels are the following: 0 keV, 98.3 ± 0.2; 1220 keV, 1.22 ± 0.20; 1763 keV, 0.22 ± 0.05; 2695 keV, 0.16 ± 0.04; and 3003 keV, 0.11 ± 0.03. The 35Ar half-life is found to be 1.787 ± 0.012 s. The present results support the findings of Wick et al. that the vector coupling constant determined from the 35Ar ground state beta decay is significantly larger than the values inferred from other super-allowed decays.
Gravitational Field Equations
Authors: Rastall Peter
Published: April 2011

An earlier, scalar theory of gravitation is assumed to be valid for a class of static gravitational fields. The theory is written in tensor form, and generalized to the case of an arbitrary gravitational field. The interaction between the field and its sources is discussed, and the linearized form of the field equations is derived. Some possible alternative field equations are considered which are compatible with the linearized Einstein equations.
Study of the Ep = 1.724 MeV Resonance in the 27Al(p, γ) 28Si Reaction
Authors: Lam S. T. , Litherland A. E. , Azuma R. E.
Published: April 2011

The 13.245 MeV level in 28Si has been populated by resonant proton capture at 1.724 MeV in the 27Al(p,γ)28Si reaction. Gamma-ray angular distributions and linear polarizations have been measured respectively with a coaxial and a planar Ge(Li) counter. Branching ratios have been extracted from the angular distributions. Spins have been assigned to the levels of 28Si with the help of the angular distribution and linear polarization results. The spin and parity of the 13.245 and 9.699 MeV levels are most probably 5− with T = 1 and 0 respectively. The assignment Jπ = 4− for the 8.411 MeV level is in agreement with the present data. A spin and parity of 3− for both the 13.245 and 9.699 MeV levels also fits the data but with more adjustable parameters. Arguments are presented to show that these assignments are unlikely. Relative measurements of the gamma-ray yields from a thick target give a value of (7.5 ± 1.5) eV for (2J + 1)ΓγΓp/Γ of the resonance. The M1 transition strength between the 13.245 and the 9.699 MeV levels is then deduced to be (0.7 ± 0.15) W.u. The known properties of the 9.699 MeV level suggest that it may be associated with an E5 oscillation of the ground state of 28Si.
Study of Delayed States in 94Nb, 108Ag, and 110Ag
Authors: Gujrathi S. C. , d'Auria J. M. , Korteling R. G.
Published: April 2011

The lifetimes and energies associated with low-energy gamma transitions from the 93Nb(n,γ)94Nb, 107Ag(n,γ)108Ag, and 109Ag(n,γ)110Ag reactions have been studied using a high-resolution Ge(Li) X-ray spectrometer. New weak transitions are observed in the decay of 110Ag at 30.84, 38.19, 41.78, and 136.65 keV, while intense gamma transitions at 105.6, 235.8, and 266.95 keV are resolved into doublets. The half-life of the state involving the intense 117.47 keV transition in 110Ag and the 215 keV transition in 108Ag is confirmed as 36.5 ± 2.0 ns and 54 ± 8 ns, respectively, while a new delayed state associated with the gamma transition of 99.404 keV (T1/2 = 30 ± 5 ns) in 94Nb is observed for the first time. The upper limits for the half-lives involving most of the intense transitions in all the three isotopes are also reported. A level scheme is proposed and discussed for 108Ag.
Determination of the Electrical Radius ka of a Circular Cylindrical Scatterer from the Scattered Field
Authors: Boerner W. M. , Vandenberghe F. H. , Hamid M. A. K.
Published: April 2011

The inverse problem of scattering for a circular cylindrical scattering geometry is considered. The transverse far field components are related to the Fourier coefficients of the circular cylindrical wave expansion in terms of the scattered field matrix. The associated determinant which describes the scattering geometry is formulated in closed form. To achieve nonsingular matrix inversion, a novel, determinate optimization procedure for the measurement aspect angles is derived and proved. Measurement techniques or experimental results are not presented. Yet, it is shown analytically that the unknown expansion coefficients can be recovered with standard double precision matrix inversion techniques to the degree of accuracy dictated only by any suitable measurement technique. Assuming the required set of expansion coefficients {an}TM and/or {bn}TE is found, it is shown that the electrical radius ka of the scatterer can be determined from four contiguous expansion coefficients in the TM as well as the mixed TM–TE cases. Only the TE case is an exception for which a more elaborate formulation exists. The relationships between contiguous expansion coefficients of both electric and magnetic type are relevant to the general cylindrical inverse problem, since the electrical radius can be directly recovered from the scattered field data. Furthermore, the scattered field can be uniquely expressed in terms of only one set of expansion coefficients associated with either the electric or magnetic vector wave functions.
Comment on Ion-Acoustic Waves in the Auroral Plasma
Authors: Unwin R. S. , Knox F. B.
Published: April 2011

Correction is made to a statement concerning a deduction about the cause of radio aurora. A possible way is suggested of reconciling the conflict of evidence for and against the occurrence of the ion-acoustic instability in the evening.
On the Theory of Guided Electromagnetic Waves on a Non-Ideal Cylindrical Structure
Authors: Wait James R.
Published: April 2011

A perturbation procedure is employed to derive expressions for the effective surface impedance and propagation constant for a circular rod with an uneven surface. The Leontovich or impedance boundary conditions are assumed to apply in a local sense. It is shown that the roughness leads to attenuation of the guided wave on the structure.
Calculations of Some Transport Coefficients in Simple Semiconductors at Low Temperatures and High Electric Fields
Authors: Kamal Jyoti , Sharma Satish
Published: April 2011

In this paper the authors have calculated Hall mobility, drift mobility, and Hall constant for a non-degenerate simple model semiconductor at low temperatures for an arbitrary electric field strength. Following Paranjape the modified distribution of phonons has been taken into account. The difference between the calculations of transport coefficients made by taking into account the modified phonon distribution and by not taking it into account is quite appreciable at high electric field. Calculations also show that for Ne = 1016/cm3 the mobility of electrons remains temperature dependent.
Raman Spectrum of Gypsum
Authors: Krishnamurthy N. , Soots V.
Published: April 2011

The Raman spectrum of an oriented single crystal of CaSO4∙2H2O has been recorded from 20 to 3600 cm−1 at 300 °K and 77 °K using polarized laser excitation. The symmetries of the observed Raman lines have been determined and the spectrum has been analyzed in terms of external lattice vibrations, internal vibrations of the SO4 and H2O groups, hydrogen bond vibrations, and combinations of these vibrations. The translatory and rotatory lattice modes of the H2O molecules have been identified and the latter have been correlated with the principal moments of inertia of the water molecule. The hydrogen bond vibration was observed at 210 cm−1 at 300 °K and 217 cm−1 at 77 °K. The assignments of the internal modes were found to be consistent with the results of previous workers. Several overtone and combination frequencies were observed, especially in the region of the ν1 and ν3 vibrations of H2O.
Studies of the Kerr Effect in High Resolution Spectroscopy
Authors: Brown J. M. , Buckingham A. D. , Ramsay D. A.
Published: April 2011

The general theory of the Kerr effect in the region of absorption bands is described. Expressions are derived for the Kerr constants B[=(nz − nx)ω/2πcFz2] and B′[=(kz − kx)ω/2πcFz2] for symmetric top molecules at frequencies close to transitions involving levels with K ≠ 0. The application of the theory to asymmetric top molecules and the inclusion of second-order effects are discussed.Kerr spectra of the 3390 Å band of formaldehyde and of the 3821 Å band of propynal have been photographed under high resolution. The most prominent lines in these spectra are those which show predominantly first-order Stark effects. Photoelectric methods are described involving (a) a rotating quarter-wave plate and (b) a rotating polarizer; they permit the recording of the pure birefringence (B) and pure dichroism (B′) respectively.
Far Infrared Spectrum of CsMnF3 at Low Temperatures
Authors: Shapiro M. M.
Published: April 2011

The absorption spectrum of crystalline CsMnF3 has been observed at 5 and 85 °K, in the region 40–180 cm−1 (250–56 μ). Three phonon lines, three 2 magnon lines, and two magnon assisted phonon difference lines are identified by their temperature dependence.
Application of Circuit Transformations to Systems of Lenses
Authors: Otis G. , Tremblay R.
Published: April 2011

The discrete elements comprising a series of lenses or an optical resonator can be treated as transmission line circuit elements. This gives an easy method to follow the paths of light rays in such structures. The usual circuit transformations can also be applied to the optical elements thus yielding a simple way to find an equivalent resonator to a complex resonator.
Self-diffusion Measurements in Pure Liquids using Spin Echoes
Authors: Sandhu H. S.
Published: April 2011

Measurements of the coefficient of self-diffusion D have been carried out in oxygen-free samples of CH2Cl2, CH2Br2, and CH2I2 using spin echoes. The results show that the plots of In D vs. 1000/T are linear. The coefficients of self-diffusion decrease with increase in molecular weight and the activation energies of self-diffusion increase with increase in molecular weight. The results appear to be in agreement with the significant structure theory developed by Eyring and Ree.
Velocity of Sound and Acoustic Attenuation in Pure Gallium Single Crystals
Authors: Lyall K. R. , Cochran J. F.
Published: April 2011

The velocity of sound for both transverse and longitudinal waves has been measured in single crystals of pure gallium. These velocity data have been used to calculate a complete set of elastic constants for gallium at 273, 77, and 4.2 °K. A survey has also been made of the acoustic attenuation in gallium at approximately 5 MHz over the range 1.5–300 °K. The measurements were made using a transducerless method which utilizes the direct electromagnetic generation of acoustic waves at the surfaces of a metal to excite standing sound waves in a slab-shaped specimen. It is demonstrated that this technique is both convenient and sensitive: changes of 1:106 in the velocity of sound in gallium were found to be readily measurable over the range 1.5–300 °K.
The Diffusion and Thermalization of an Electron Cloud Injected into an Afterglow Plasma
Authors: Andel H. W. H. Van
Published: April 2011

The steady state distribution function for a suprathermal electron cloud injected into a cylindrical plasma is found as a function of position and velocity by solving the Boltzmann equation numerically in the Fokker–Planck approximation with an added term taking into account electron-neutral collisions. The injection is assumed to take place at one end of the cylinder, and an axial magnetic field is assumed present. A number of representative solutions are given for various choices of the parameters of the problem.
Decay of 142La
Authors: Tong S. L. , Prestwich W. V. , Fritze K.
Published: April 2011

The energies of the gamma rays following the beta decay of 92.5 min 142La have been precisely measured, and a coincidence measurement with a NaI(Tl) and Ge(Li) system was made by gating the NaI(Tl) at 641 keV. With these results, the decay scheme of 142Ce derived by Prestwich and Kennett was modified. The beta branching ratios of the decay of 142La to the ground and excited states of 142Ce have also been obtained by simultaneous gamma and 4π beta countings with a 3 in. × 3 in. NaI(Tl) detector and a 4π-proportional counter.
Spectrum of AsS. I. Analysis of the A′2Π3/2–X2Π3/2 Band System
Authors: Shimauchi Midori
Published: April 2011

The emission spectrum of the AsS radical, excited in a quartz tube by a 2450 MHz oscillator, was photographed on a high resolution spectrograph from 2450 to 6900 Å. Seven bands around 6000 Å showing clear rotational structures were chosen for the first rotational analysis of the AsS spectrum. The bands were found to arise from a 2Π3/2–2Π3/2 transition. The rotational and vibrational constants of the two states derived from the present work are consistent with the previous vibrational analysis of the A′2Π3/2–X2Π3/2 system. The constants of the upper doublet component of the ground state, X2Π3/2, are ωe = 562.40 cm−1, ωexe = 2.02 cm−1, re = 2.0216 Å; the constants of the A′2Π3/2 state are ΔG′(1/2) = 403.37 cm−1, ν0,0 = 18 621.21 cm−1, re = 2.2500 Å.
Positive-Parity Bands in 29Si
Authors: Pilt A. A. , Spear R. H. , Elliott R. V. , Kuehner J. A.
Published: April 2011

A study has been made of several high spin members of the ground state (Kπ = 1/2+) and first-excited state (Kπ = 3/2+) rotational bands in the presumed oblate nucleus 29Si. Gamma-ray angular distribution and linear polarization measurements have confirmed the spin and parity of the 4081 keV level to be 7/2+, and levels at 4742 and 5283 keV have been shown to have Jπ = 9/2+ and (7/2+, 3/2+) respectively. Branching and mixing ratios for the transitions from these states have also been determined; in conjunction with previously measured lifetimes, transition strengths are calculated. The results are compared with the predictions of a Nilsson-model calculation including the effects of coriolis mixing of the low-lying positive parity bands.
Méthode d'Alignement au Moyen d'une Mire à Foyers Multiples à Phase Inversée
Authors: Boivin Germain , Gagnon Remi
Published: April 2011

We propose the use of a multiple-focus target to perform the alignment of a given number of points along a given axis. The target consists of several parts of Soret zones plates whose focusing properties are well known. The focal length of each zone plate is determined from the Gaussian form of the lens equation. Experiment showed that over a distance of 12 m the alignment can be done with an accuracy of a few microns.
Phase Transitions in Two-Dimensional Spin Systems
Authors: Betts D. D. , Elliott C. J. , Ditzian R. V.
Published: April 2011

The first nine coefficients have been derived in the exact high temperature expansion of the fluctuation in the long range order in the XY model on the triangular and square lattices. For the triangular lattice seven coefficients have also been obtained in the expansion of the fourth-order fluctuation. The method of conformal transformations has been developed in a form suitable for the analysis of series of this type. Clear evidence is obtained in favor of a phase transition for which the critical index of the fluctuations is γ ≈ 3/2. The critical temperatures kTC/J for the triangular and square lattices are 1.500 ± 0.006 and 0.900 ± 0.006 respectively.
Reliability of Shell Model Calculations using the Dispersion Relation Approach
Authors: Hodgson R. J. W.
Published: April 2011

Two techniques for deriving the Born approximation from the two-nucleon phase shift data in states having l ≤ 4 are employed to study the influence of the high energy form of the phase shifts in deducing two-body matrix elements and shell model spectra. A comparison is made with results obtained by other approaches.