bluuebunny/crossref_metadata_2025 huggingface dataset:
Lifetimes and Oscillator Strengths in Atomic Barium
Authors: Dickie L. O. , Kelly F. M.
Published: April 2011

The lifetime of the 5d6p1P1levelatomic barium has been determined from a measurement of the Hanle resonance in the 3501 Å line. The lifetime of this level is 12.17 ± 0.09 × 10−9 s. The lifetimes of a number of levels of atomic barium are collected and absolute oscillator strengths are calculated and compared.
B(E2) of the First 2+ Level of 150Sm
Authors: Cameron J. A. , Zámori Z.
Published: April 2011

The cross section for the inelastic scattering of 4He ions exciting the first 2+ state of 150Sm was compared with the cross section for elastic scattering. From the measured ratios at 9 and 10 MeV bombarding energy, the reduced transition probability was found to be[Formula: see text]
Vibrational Spectrum and Specific Heat of Tantalum
Authors: Pal Satya
Published: April 2011

The vibrational spectrum and specific heat of tantalum are calculated on the basis of the lattice dynamical model of Sharma and Joshi. The calculated specific heat and the corresponding equivalent Debye temperature show fair agreement with the experimental data of Clusius and Losa.
Distributions of the Initial Fragment Kinetic Energy in Binary and Ternary Fission
Authors: Vitta P. B.
Published: April 2011

The statistical theory of nuclear fission was originally developed to deal with binary fission. An attempt is made to extend the theory to the case of ternary fission. The probability of a fission mode, given that the nucleus divides into three fragments, is first calculated. Attention is thereafter focused only on the probability distribution of fission modes representing the various possible allocations to the fragment translational motion and internal excitation of the energy available for both translation and excitation. This leads to ternary-fission distributions of the initial kinetic energy (and to complementary distributions of the initial excitation energy) of the fissioning nucleus. Our results show that the ternary-fission distributions of the initial kinetic energy are wider with peaks at higher values of kinetic energy than the corresponding binary-fission distributions obtained previously. The (spontaneous-) ternary-fission distributions are peaked at energies of the order of 1 MeV and have full-widths-at-half-maximum (FWHM) in the neighborhood of 3 MeV. These figures are of experimental interest, since they may be used to predict the energy spectra of the fission fragments in ternary fission.
Lifetimes of the 26 and 110 keV levels in 56Mn
Authors: Boulter J. F. , Prestwich W. V.
Published: April 2011

Using thermal-neutron capture on natural manganese targets, delayed coincidence lifetime measurements have been made for the 26 keV level: T1/2 = 8.65 ± 0.50 ns, and the 110 keV level: T1/2 = 5.08 ± 0.15 ns in 56Mn. A systematic error in the 26 keV lifetime measurement, which arises when the 26 keV level is populated by a γ ray which has cascaded through the delayed 110 keV level, has been examined. The experimental reduced M1 and E2 transition probabilities were calculated for the 26 and 84 keV transitions. The reduced M1 strength for the 26 keV transition and the ground-state magnetic dipole moment of 56Mn have been compared with theoretical results obtained using the magnetic moments of neighboring odd-A nuclei as the base states.
Electrode Ablation in a Spark Discharge
Authors: Sharah A. , Cormack G. D.
Published: April 2011

The entry of electrode material into an immobile spark discharge is studied. The ablation time tb of several electrode materials having a wide range of thermal and physical properties was measured in both hydrogen and argon atmospheres using spectrophotometric techniques. Gas pressure, kind of gas, and current magnitude had virtually no effect on tb over the range of parameters studied. While cathode ablation was always present, anode ablation was found to be immeasurably small. Generally experimental and theoretical values of ablation time agreed, the latter being calculated from the hot-spot model for ablation.
Franck–Condon Effects in the Luminescence of CdS
Authors: Malm H. L. , Haering R. R.
Published: April 2011

In CdS the interactions between the lattice and the electronic excitations which luminesce can be understood in terms of a Franck–Condon model. Calculations for the value of the electron – LO phonon interaction parameter S done by Toyozawa for a bound carrier are extended to include the free exciton, the bound exciton, and the bound to bound transition. Experiments showed that Ŝ for excitons varied inversely with exciton size in agreement with theory. Calculations which showed that [Formula: see text] for the bound to bound transitions varied with the donor–acceptor separation were verified by experiment.
252Cf Fission Fragment Energy Loss Measurements in Elementary Gases and Solids as Compared with Theory
Authors: Hakim M. , Shafrir N. H.
Published: April 2011

Energy loss of 252Cf fission fragments in 15 gases and solids, representing a wide range of atomic numbers throughout the periodic system, has been measured using a calibrated Si surface barrier heavy ion detector. The data are used for a detailed and systematic comparison with existing theoretical treatments of the electronic energy loss mechanism showing that none of them gives overall good agreement for all stopping substances.The Bohr expression for heavy stopping substances, which shows consistent deviation from experiment for the entire range of stopping media, suggests that based on this approach, a semi-empirical modification can be derived.
Utilisation d'un Facteur de Boltzmann dans l'Etude des Propriétés Thermodynamiques de Liquides Polaires
Authors: Brusset Henry , Depeyre Dominique , Herpe Irène
Published: April 2011

A study on interaction potential between polar molecules is made for fitting the potential. A solution is proposed for returning to a potential that is independent of molecule orientation. This solution uses a weighted Boltzmann factor in the calculation of potential energy. The method of calculation is given.
An Infrared Spectrum of CO2 Dimers in the "Locked" Configuration
Authors: Mannik L. , Stryland J. C. , Welsh H. L.
Published: April 2011

The two components of the (ν1, 2ν2) Fermi doublet of gaseous CO2 in an absorption path length of 56 m at 192 °K show a complex structure. When the allowed C16O18O absorption and the pressure-induced CO2 absorption are removed by computational procedures, the residual spectrum consists of two similar symmetric patterns of five maxima. These are interpreted in terms of the rotation and vibration of (CO2)2 dimers held by quadrupole–quadrupole interaction in the locked T position at an intermolecular distance of 4.1 Å.
Microwave Phase Measurements Associated with the Goos–Hänchen Shift
Authors: Arthur L. , Read A. , Dagg I. R. , Reesor G. E.
Published: April 2011

Microwave phase measurements, using the Robertson homodyne detection method, have been made in the field outside a dielectric prism after microwave energy has experienced total internal reflection. The phase changes that occur in this case are explained by extending Artmann's theory of the Goos-Hänchen effect to microwave optics. Satisfactory agreement between the theory and measurements has been obtained for angles of incidence from 40 to 50° on a dielectric boundary for which the critical angle is 36.4°.
Higher-Order Corrections to the Optical Potential for Kaonic Atoms
Authors: Eisenberg J. M. , Guy Reed
Published: April 2011

Second-order corrections to the optical potential for kaonic atoms are evaluated in the form of an approximate, local potential which takes into account an isovector correlation function but omits Pauli and hard-core correlations. The corrections are found to be very small, a result not appreciably modified when rough estimates of the consequences of Pauli correlations are considered.
The Vibration–Rotation Spectrum of Ammonia Gas. II. A Rotational Analysis of the 6450 A Band
Authors: McBride J. O. P. , Nicholls R. W.
Published: April 2011

A rotational analysis of the 5ν1 (6450 A) band in the vibration–rotation spectrum of ammonia is presented here. The QP, QQ, and QR branches of a parallel transition are observed for values of J′ and K′ less than 6. Members of the SQ and OQ branches are observed with very low intensity. The molecular constants of the molecule in the (5, 0, 0, 0) vibrational level were determined; the N–H bond length is 1.015 ± 0.005 A and the bond angle is 112.0 ± 0.8° for this vibrational level. The potential energy to inversion of the molecule by excitation of the ν1 vibration only is 51 800 ± 1200 cm−1. The width of individual rotational lines increases with increase in J′ and K′. This increase in width is characteristic of a tunnelling mechanism. It may be due to the interaction between the normal modes of vibration at large vibrational energies. This analysis should improve the usefulness of the 6450 A band of ammonia for monitoring the temperature and pressure of the Jovian atmosphere.
Rotational Analysis of the A2Π–X2Σ+ Band System of the BeCl Molecule
Authors: Colin R. , Carleer M. , Prevot F.
Published: April 2011

A rotational analysis has been performed on the 0–0, 1–1, 1–0, and 2–1 bands of the A2Π–X2Σ+ band system of the BeCl molecule photographed at high resolution in emission from a microwave discharge. The following principal molecular constants have been obtained.[Formula: see text]Inspection of the low J value lines shows that the A2Π state is a regular state derived from the electronic configuration σ2σ2π4π although the Λ-doubling constants p and q are of opposite sign.
The Stokes' Shift in Impurity Spectral Lines. II. Relationship to the Adiabatic Approximation Approach
Authors: Barrie Robert , Sharpe I. W. , Jones B. L.
Published: April 2011

The derivation of the Stokes' shift has been performed without making the adiabatic approximation. A canonical transformation is used to show the relationship between that method and the more usual one in which the adiabatic approximation is made.
Characteristic Parameters of a Beam with a Gaussian Irradiance Distribution
Authors: Lit John W. Y. , Boulay Russell
Published: April 2011

This describes a simple method to find two important characteristic parameters of a beam with a Gaussian irradiance profile—the position of the plane of the beam waist and the value of ω0 in that plane. It is necessary to observe the positions of maximum or minimum irradiances along the beam axis in the field diffracted by a circular aperture. These positions occur at places where the direct geometric-optical wave is in phase or out of phase with the boundary-diffraction wave.
Analysis of Counting Distributions with a Complex Exponential Character
Authors: Lichtenberger P. C. , Stevens J. R. , Newton T. D.
Published: April 2011

The analysis of counting distributions which can be analytically represented by a sum of exponential functions convoluted with a "prompt instrumental resolution function" has attracted much attention in the past. Because of the difficulty of unfolding the prompt resolution function from the experimental data, experimentalists have analyzed that part of the distribution which occurred at times longer than the time at which the peak of the distribution occurred. A model is proposed which permits the prompt resolution function to be unfolded and the entire counting distribution analyzed in cases where the prompt resolution function can be approximated by a double-sided exponential. The model is tested on Monte-Carlo simulated data. An algorithm which combines the best features of the gradient search and the Taylor-series search is used to obtain a least-squares estimation of the nonlinear parameters. Since the correct parameters are known, a realistic estimation of the errors associated with the analysis is obtained.
Search for Structure in 3He
Authors: Skopik D. M. , Shin Y. M.
Published: April 2011

The results of measurements on the 3He(e,e′d)1H reaction are presented. No evidence for structure in 3He has been observed over the energy region 16–27 MeV.
Pulse Duration of a Mode-Locked Nd–Glass Laser Varying the Cavity Length and the Dye Transmission
Authors: Busca G. L. , Bergeron M.
Published: April 2011

A recently introduced technique, the ultrahigh-speed photography of ps light pulses, was used to study the dependence of the pulse duration of a passively Q-switched Nd +3–glass laser on the cavity length and the dye transmission. A constant duration, within the experimental error, was found.
On the Validity of Tietz Potential Functions for Diatomic Molecules
Authors: Rai S. B. , Sharma V. N. , Rai D. K.
Published: April 2011

The potential energy curves for several diatomic molecules have been calculated by using Tietz potential energy functions and the values thus obtained have been compared with that of RKRV. It is found that in some cases this empirical form is a good approximation to the true curve.
Total Scattering Cross Sections in Two-Body Strong Interactions Calculated by an Algebraic Approach Using the Group SU(1,3)
Authors: Kalman C. S.
Published: April 2011

A method is developed for the calculation of total scattering cross sections in two-body strong interactions by an algebraic approach using the group SU(1,3). A general discussion of the method, its historical development, and a possible theoretical basis is presented. Total cross sections for a total of 95 events based on 8 parameters are predicted. Only 19 of these cross sections have been experimentally measured. Of these, 7 consist of only l experimental measurement and so cannot be used. The remaining cases are sufficient only to show that the predictions seem to be of the correct order of magnitude.
Absorption Spectrum of HSiI
Authors: Billingsley J.
Published: April 2011

A new absorption spectrum in the region 4600–5600 Å has been discovered in the flash photolysis of silyl iodide, SiH3I. A rotational analysis, together with the observation of a deuterium isotope shift, has shown that the spectrum is due to the HSiI radical.The lower electronic state of HSiI is a 1A′ state with a bond angle of ~103°, and the upper state is 1A″ with angle ~116°. Axis-switching effects, due to the increase in bond angle, cause the appearance of ΔK = 0, ± 2 subbands, in addition to the ordinary ΔK = ± 1 subbands.
Response Time of the Magnetosphere to the Interplanetary Electric Field
Authors: Rostoker Gordon , Lam Hing-Lan , Hume William D.
Published: April 2011

Data from the IMP-1 satellite are used to determine the lag time between the response of the index of geomagnetic activity AE to fluctuations in the azimuthal component of the interplanetary electric field as measured in the solar ecliptic coordinate system. The lag time is found to lie in the range 30–50 min. The magnitude of the lag time is related to the average energy content of the magnetosphere.
Experimental Data Concerning the Quadruplet Correlation Function of Simple Liquids
Authors: Egelstaff P. A. , Wang S. S.
Published: April 2011

The second derivative with respect to pressure of the liquid structure factor for neon is obtained from the data of de Graaf and Mozer. After testing these data for physical significance, we conclude that they are related to an integral over the quadruplet correlation function. It is shown that local arrangements of four atoms determine this derivative.
Calculated Rydberg States of the PO Molecule
Authors: Ackermann F. , Lefebvre-Brion H. , Roche A. L.
Published: April 2011

The Rydberg States of the PO molecule, converging to the ground state of the PO+ ion, are calculated using the LCAO–MO SCF orbitals of the molecular ion core. An adjustment between the observed and calculated values for the energy of the first Rydberg A2Σ+ state gives a value of about 66 400 cm−1 for the ionization potential of PO. The agreement between the experimental and calculated values is very good for the other observed Rydberg states. In the 5300–3800 Å region, no more than four 2Σ+ Rydberg states are expected, which supports the "deperturbation" procedure carried out by Verma. A comparison is made between the p, d, and ƒ complexes in PO and NO. The B2Σ+ state appears to be a valence state corresponding to the electron excitation from an antibonding (vπ)* orbital to a weakly antibonding (uσ)* orbital.
Field-Ion Microscopy of Tungsten Bombarded by Low-Energy Argon Ions
Authors: Gregov B. , Lawson R. P. W.
Published: April 2011

The investigation of low-energy ion radiation damage in tungsten by field-ion microscopy is discussed. An experimental arrangement is described in which prepared field-ion microscope specimens may be bombarded in situ by ions from an ion gun. The background pressure in the range of 10−11 Torr allows bombardment to be carried out while the high voltage is off. Results of specimens bombarded with Ar+ ions in the 150–450 eV range at 63 °K are described. Diffusion of self-interstitials upon annealing the irradiated specimen from 63 to 78 °K has been observed. Besides point defects, clusters of vacancies and interstitials have been observed on specimens bombarded with 400 and 450 eV Ar+ ions. The irradiation-induced defect density on the side of the microscope specimen facing the ion beam is approximately double that on the far side.
Electronic Structure of Liquid Metals from Nonlocal Energy-Dependent Model Potentials
Authors: Chan T. , Ballentine L. E.
Published: April 2011

Calculations of the density of electronic states and related quantities are reported for liquid Bi, In, and Hg. The nonlocal nature of the pseudopotentials is fully taken into account, and their energy dependence is approximated by an effective mass so that the Green function method is applicable. The density of states of Bi is found to be smoother than in a previously published calculation which used a local pseudopotential. The density of states of In is found to be nearly free-electron-like, indicating that an explanation of the photoemission spectrum must be sought elsewhere. A modest dip in the density of states of Hg is found, but it is much smaller than that conjectured by Mott.
On the Interaction of Positrons with Argon
Authors: Hewson Peter W. , Jones Garth , Vogt Erich W.
Published: April 2011

A semi-phenomenological model of the interaction of positrons with atoms is outlined, and some model properties—enhancement factors, effective mass, and effective charge—are calculated using a local density approximation. These properties are used with a one parameter polarization potential to predict the electric field dependence and the temperature dependence of the positron annihilation rate in argon gas. Comparison of these predictions with experimental data shows good agreement for the electric field dependence, but the predicted temperature dependent effect is less than published experimental results. The model is also applied to helium, with unsatisfactory results, and a prediction of the electric field dependence of the positron annihilation rate in krypton is made.
Vibrational Energy Transfer in Carbon Monoxide
Authors: Dawson P. H. , Tam W. G.
Published: April 2011

The role of V–V processes in vibrationally excited CO systems in the longitudinal and transverse flow chemical lasers is studied. Initial vibrational energy distributions of CO formed by the O + CS reaction are deduced from chemiluminescent data using calculated values of the vibration energy exchange probabilities. The time evolution of the population distributions is then obtained by computer simulation. The results are compared with experimental measurements. The effects of excess oxygen and of "cold" CO on the population distributions are also discussed.
Solution of the Bethe–Goldstone Equation in Finite Nuclei from N–N Phase Shift Data
Authors: Hodgson R. J. W.
Published: April 2011

An approach is outlined wherein the Bethe–Goldstone wave function may be computed in a shell-model basis from a knowledge of the harmonic-oscillator matrix elements. These in turn may be derived from the N–N phase shifts by a number of different methods. The Pauli operator is treated exactly in the space of two-particle shell-model states. The method is applied to a calculation of the levels of 18O and 18F and results obtained using different two-body matrix elements are compared.
Comparison of Plane-Wave Approximations in Potential Scattering
Authors: Ebden John R. , Darewych J. W.
Published: April 2011

We compare four different plane-wave approximations for scattering by short-range potentials. These four are the first and second Born approximations, the plane-wave Schwinger approximation and a restricted form of Ford's renormalized Born approximation. For the Yukawa and Gaussian potentials, the differential and total cross sections are calculated in the energy range [Formula: see text] (arbitrary units) and for dimensionless coupling constants ranging between 0.1 and 10. The first Born and renormalized Born are 'first-order' approximations, requiring an order of magnitude less calculational labor than the second Born and Schwinger approximations. The results suggest that the restricted renormalized Born approximation is rarely better than the ordinary first Born approximation. The Schwinger plane-wave approximation is always better than the second Born approximation and since these two involve the evaluation of identical expressions, the Schwinger approximation is always to be preferred over the second Born. The Schwinger plane-wave approximation gives quite consistently the best results of the four methods considered, but even it is not be be trusted for calculating differential cross sections at large angles or for reproducing "resonance structure" in total cross sections.
Measurement of Temperature and Density in the Upper Atmosphere Using an Electron Beam
Authors: DeLeeuw J. H. , Davies W. E. R.
Published: April 2011

Rotational temperature and density measurements from 75 to 150 km at Fort Churchill, Manitoba, have been made from observations of the local fluorescence produced by a rocket-borne electron gun in the 0–1 band of nitrogen's first negative system.The engineering aspects of the experiment are discussed together with a presentation of the results from the electron beam apparatus and hot cathode ionization gauges.
Conduction Band Parameters in GaSb from High-Temperature Transport Measurements
Authors: Basinski Joseph , Kwan Clarence C. Y. , Woolley John C.
Published: April 2011

Measurements of resistivity and Hall coefficient as a function of magnetic field (0–3.2 Wb/m2) and temperature (25–200 C) have been made on samples of Te-doped GaSb. The results have been analyzed in terms of a two-conduction-band model with minima at Γ1 and L1, using the method reported by Kwan et al. This analysis yields a value for the Γ1–L1 band separation of 0.097 ± 0.002 eV, when linearly extrapolated to 0 K, and a temperature coefficient of −3.4 × 10−5 eV/K. The measurements of the Hall coefficient at 0.87 Wb/m2 and the zero-field resistivity have been extended to 360 C. These data have been analyzed using a four-band model (Γ1, L1X1, and Γ15 V), thus giving the temperature dependence of electron mobility in the Γ1 and L1 bands. The electron mobility values for the L1 band have then been fitted to a semiempirical relation, obtained by assuming appropriate scattering mechanisms.
Electronic Structure for a Distorted Chain
Authors: Wong T. C. , Tong B. Y.
Published: April 2011

A linear chain with impurities randomly distributed along it is studied by means of the node counting method. The host atoms as well as the impurity atoms are represented by negative δ-function potentials with different strengths. The solvent atoms are distorted in a specific manner about each impurity atom. The integrated density of states are calculated near a band gap for different impurity concentrations and for various degrees of distortion. It was found that without distortion the gap remains practically structureless, whereas with distortion the energy levels diffuse into the gap. The results are qualitatively similar to that of a model liquid.
Nonlinear Eigenvalue Problem of a Self-Sustained Electrical Discharge
Authors: Wilhelm H. E.
Published: April 2011

An analytical solution is presented for the nonlinear boundary-value problem of a one-dimensional, electrical model discharge, in which the production of plasma by ionization is balanced by the plasma losses due to recombination and diffusion. The maximum value [Formula: see text] of the electron–ion density in the center of the discharge is given as the positive-real eigenvalue of a transcendental equation resulting from the boundary conditions. It is shown that a self-sustained, steady-state discharge exists if the dimensionless discharge number [Formula: see text] is numerically equal to a certain function [Formula: see text] of the dimensionless eigenvalue [Formula: see text]. For example, it must be (i) [Formula: see text] for [Formula: see text], i.e. when recombination is neglected, α = 0, and (ii) [Formula: see text] for [Formula: see text], i.e. when recombination is considered, α > 0 (a = half wall distance; ε, D, α = ionization, diffusion, and recombination coefficients respectively). Plots of the eigenvalue [Formula: see text] versus Z and of the density distribution n(x) of the charged particles are given.
Nucleon Separation and Pairing Energies, Decay Energies, and Atomic Masses for
Authors: Meredith J. O. , Barber R. C.
Published: April 2011

A set of 45 precise determinations of doublet spacings in the mass spectra of rare-earth chlorides has been combined with existing nuclear reaction and decay Q values and atomic mass data in a least-squares adjustment of atomic mass differences. For nuclides in the region [Formula: see text] the following quantities have been calculated: separation energies for the last pair of neutrons and for the last neutron (S2n, Sn), the neutron pairing energy (Pn), separation energies for the last pair of protons and for the last proton (S2p, Sp), the proton pairing energy (Pp), Q values for α and β− decays, and the masses. The systematic variations of these quantities are illustrated and discussed.
Pulse Distortion by Anisotropic Plasmas
Authors: Bachynski M. P. , Gibbs B. W.
Published: April 2011

Experimental measurements have been performed of electromagnetic pulses transmitted through a plasma under conditions of strong interaction (strong heating of the electrons) between the incident wave and the plasma. Severe pulse distortion depending on the plasma density and pulse shape can occur. The leading edge of the pulse does not always show maximum penetration through the plasma.
Combined Rayleigh and Kelvin Instability of a Hall Plasma with a Vertical Magnetic Field
Authors: Bhowmik G. , Talwar S. P.
Published: April 2011

The problem of Rayleigh–Taylor and Kelvin–Helmholtz instability for an electrically conducting incompressible Hall plasma supported by a nonconducting and uniformly streaming compressible gas is investigated with an ambient vertical magnetic field. The resistivity and the finite ion Larmor frequency are both found to have a destabilizing effect as also the streaming speed and the compressibility of the gaseous medium.
Oscillatory Spectral Distribution of the Photoelectromagnetic Effect Associated with Direct Interband Transitions in Germanium
Authors: Barbarie A. , Fortin E.
Published: April 2011

A rather simple and straightforward experimental method of studying direct interband optical transitions between Landau levels in semiconductors is achieved by observing the oscillatory spectral distribution of the photoelectromagnetic effect resulting from a quantizing magnetic field. The method is applied here to germanium at a temperature of 6 K, over the energy range 0.9–1.1 eV, using linearly polarized light parallel and perpendicular to magnetic fields of up to 70 kG applied along the [111] direction of the crystals. The spectral oscillations are analyzed in terms of current magneto-optical theories to give a value for the direct band-gap energy (Eg = 0.888 ± 0.001 eV) for the ground state exciton binding energy (Eex = 1.5 ± 0.3 meV) and an estimate of nonparabolicity and excitonic effects on higher-order transitions. A possible relationship between the oscillation amplitude and the bulk mean free path of the carriers is also examined.
Drude Theory of Electromagnetic Waves in an Inclined Magnetic Field. I. One-Band Model of Charge Carriers
Authors: Halevi P.
Published: April 2011

Magnetoplasma waves propagating at an angle to a static magnetic field are investigated for an isotropic system of carriers. The dispersion relations and polarizations are presented in graphical form, and useful expressions are derived for limiting cases. The longitudinal and transverse modes interact, leading to coupled modes in the vicinity of the plasma frequency. Damping and nonlocal effects are also discussed.
Observable Many-Body Effects of the Two-Body Unobservable Potential
Authors: Wong N. N. , Razavy M.
Published: April 2011

A two-body transparent potential, which produces no observable phase shift in two-particle scattering, is constructed explicitly. This potential is used to calculate the energy of infinite nuclear matter by applying the perturbation theory and its effects on the many-body system are investigated.
Use of 155Eu in the Measurement of Gd L Subshell Yields
Authors: Douglas D. G.
Published: April 2011

The subshell fluorescence yields ω2 and ω3 and the Coster–Kronig yield f23 have been measured for Gd by the method of coincidence study of the X rays emitted by 155Eu.The result is ω2 = 0.182 ± 0.008, ω3 = 0.187 ± 0.006, and f23 = 0.223 ± 0.011. The values for ω2 and ω3 are close to theoretical predictions and to the experimental results of other workers on the neighboring element Tb. However, there is serious disagreement in the f23 values.
Effect of Biquadratic Exchange upon Ferromagnetic Two-Magnon Bound States
Authors: Pink D. A. , Tremblay P.
Published: April 2011

We have calculated the effects of an isotropic biquadratic exchange term having a coupling constant of moderate size [Formula: see text] upon the two-magnon bound state spectrum of an otherwise Heisenberg ferromagnet, with or without single-ion anisotropy, at zero temperature. The bound states are labelled by a wave vector q which we have taken to be in the [111] direction. The two principal results found are: (i) The large effect that K/J has in localizing the '"exchange coupled" bound state, S1 for all values of q above the two-magnon band, when it is sufficiently negative and the spin or pseudo-spin magnitude is of sufficient size. (ii) The change in the value of the wave vector, as K/J changes, at which the one-magnon spectrum crosses that of the "single-ion" bound state, S0.
Spectroscopie par Source Laser. I. Etude Expérimentale des Intensités et Largeurs des Raies de la Transition 0001–(1000,0200)I de CO2
Authors: Arié Eric , Lacome Nelly , Rossetti Colette
Published: April 2011

The 0001–(1000-0200)I band of CO2 has been studied by a spectroscopic method using a monochromatic, single mode stabilized laser source. Half-width and integrated intensity values have been deduced for every line.
The Use of Coherent States in the Theory of Quantum Crystals
Authors: Noolandi J. , Kranendonk J. Van
Published: April 2011

The coherent state formalism is applied to the calculation of the phonon frequencies in quantum crystals. The normal mode frequencies are determined using an expansion in powers of the displacements of the centers of the single-particle distributions rather than of the particles. The known results of the RPA and of Meissner's inversion of the displacement–displacement correlation function are derived in a simple way, and the connection with Feynman's method for liquid helium is discussed. The method of constant short-range correlations is introduced and compared with the recent work of Koehler and Werthamer.
Bombardment-Induced Amorphization in WO3 and its Use in Deducing Mean Damage Ranges (Studies on Bombardment-Induced Disorder. VI)
Authors: Lam Nghi Q. , Kelly Roger
Published: April 2011

WO3, though at first sight simply another example of an anisotropic oxide subject to bombardment-induced amorphization, has particular importance in that the depth of the amorphization (Ra) can be estimated with great accuracy. The procedure is based on preparing anodic WO3, crystallizing it on its metal substrate at 350 or 450 °C, bombarding it, and then making direct use of the brilliant interference colors. Only Kr impact was studied, the values of Ra being found to lie in the region of 50 to 390 Å for Kr energies of 4 to 35 keV. It is argued that such values of Ra can be used to deduce [Formula: see text], the mean damage range. One postulates that the fraction of atoms initially displaced at Ra is unique but otherwise unspecified. This means that the quantity γ ≈ (Bt) exp (−ξ2/2), where Bt is the dose, ξ stands for [Formula: see text] and [Formula: see text] is the mean damage straggling, should be invariant for a given bombardment energy. In solving this equation advantage can be taken of the fact that the ratio [Formula: see text] tends to be constant (1.6 ± 0.2) for intermediate mass ratios and low energies. The result was a series of estimates of [Formula: see text] which could be shown to be closely similar to the exact Thomas–Fermi values of Winterbon.
External Conical Refraction of Elastic Waves in Crystals
Authors: Nayar S. R. Prabhakaran , Viswanathan K. S.
Published: April 2011

The existence of 'special points' in the section of the wave surface by the principal planes is investigated for tetragonal and cubic classes of crystals. It is shown that the special points are determined by a cubic equation, and a condition, which should be satisfied by the elastic constants, so that external conical refraction can occur in the principal plane for any crystal, has been derived. The direction of the wave normals for which external conical refraction will occur has been calculated for several crystals of the tetragonal and cubic classes, and the results are tabulated in two tables.
The Repulsive Part of the Potential Between Hg Atoms and Light Atomic Projectiles
Authors: Wijngaarden A. van , Miremadi B. , Baylis W. E.
Published: April 2011

Interatomic potentials are studied by means of a crossed beam apparatus consisting of a target chamber in which a monoenergetic beam of H, He, B, and N ions of energies E < 70 keV interacts with a thermal beam of Hg atoms. Angular distributions for the scattering of all charge states of 1H, 4He, 11B, and 14N are measured in the range of 17° < θL < 60°. All measured cross sections are in good agreement with the theory for scattering in a Thomas–Fermi potential to which Lindhard's theoretical estimates are shown to be quite accurate approximations. A Padé approximant is derived for the Thomas–Fermi potential and is used to calculate tables of Thomas–Fermi scattering parameters.
Neutron Activation Resonance Integral of 74Ge and 76Ge and Evaluation of the 74Ge keV Neutron Radiative Capture Cross Section and Resonance Integral
Authors: Ricabarra M. D. , Turjanski R. , Ricabarra G. H.
Published: April 2011

Values of the reduced activation resonance integral relative to the thermal cross section I′/σ0 of 74Ge and 76Ge were determined relative to gold by measuring cadmium ratios in a reactor spectrum.A lithium-drifted germanium γ-ray spectrometer was used to resolve the activities of the samples.The results for 74Ge are I′/σ0 = 1.514 ± 0.031 and I′ = 0.681 ± 0.123 b with an assumed σ0 = 0.45 ± 0.08 b; for 76GeI′/σ0 = 12.00 ± 0.16 and I′ = 1.992 ± 0.359 with an assumed σ0 = 0.166 ± 0.030 b.The values obtained for I′ are in serious disagreement with the values calculated with neutron resonance parameters and confirm previous results obtained in similar keV average resonance spacing isotopes.Due to this fact a careful evaluation of the keV neutron radiative capture cross section and resonance integral for 74Ge was undertaken.The evaluation and comparison with the experimental value of the resonance integral shows first that for nuclides with an average resonance spacing of keV the unresolved resonance integral has been seriously underestimated in many evaluations, and second that between 10 and 100 keV, resonance integrals calculated with smooth low resolution activation cross sections give a better calculation of neutron captures than that obtained with neutron resonance parameters.
On the Inverse Problem of Scattering from a Perfectly Conducting Elliptic Cylinder
Authors: Vandenberghe F. H. , Boerner W. M.
Published: April 2011

The inverse problem of electromagnetic scattering from a perfectly conducting elliptic cylinder for the low-frequency case is considered. The approach is based on the model technique presented in Boerner and Vandenberghe, conjecturing that the salient features of the scatterer can be determined from the far scattered field via matrix inversion. This follows the low-frequency formulation of the scattered field as given by Udagawa and Miyazaki rather than from an expansion in the elliptic cylindrical wave functions. It is then shown that the characteristic parameters of the ellipse, i.e. the principal axes a′ and b′ and the numerical eccentricity ε, can be directly recovered from the expansion coefficients associated with circular cylindrical wave functions, as is presented in Udagawa and Miyazaki.
The Decay of 117Cd and 117Cdm
Authors: Gregory P. R. , Johns M. W.
Published: April 2011

The energy levels of 117In have been investigated following the β decay of 3.4 h 117Cdm and 2.5 h 117Cdg. Using high resolution Ge(Li) detectors singly and in coincidence, 127γ transitions have been observed. Eighty-five of these transitions have been classified by both coincidence data and energy fit, 29 weak transitions by energy fit alone, and 12 remain unclassified. Thirty-seven levels in 117In have been established; of these, 24 are low spin states fed from the ground state and 13 are high spin states fed from the isomer. Spin and parity assignments for the newly established levels are discussed.
q-Equivalent Hamiltonian Operators
Authors: Razavy M.
Published: April 2011

From the equation of motion and the canonical commutation relation for the position of a particle and its conjugate momentum, different first integrals of motion can be constructed. In addition to the proper Hamiltonian, there are other operators that can be considered as the generators of motion for the position operator (q-equivalent Hamiltonians). All of these operators have the same classical limit for the probability density of the coordinate of the particle, and many of them are symmetric and self-adjoint operators or have self-adjoint extensions. However, they do not satisfy the Heisenberg rule of quantization, and lead to incorrect commutation relations for velocity and position operators. Therefore, it is concluded that the energy first integral and the potential, rather than the equation of motion and the force law, are the physically significant operators in quantum mechanics.
Circularly Polarized Waves in Magnetoplasmas Containing Negative Ions
Authors: Hung Nguyen The , Paquette G.
Published: April 2011

We present a systematic investigation of the right-hand waves propagating along a uniform magnetic field in a homogeneous, unbounded plasma made up of electrons, positive ions, and negative ions. It is shown first that negative ions give rise to a new resonance, a new stop-band, a new ion whistler, and an ion cyclotron wave in the right-hand mode of propagation. We study also the thermal effect of the plasma, comparing the dispersion characteristics for three distributions: the Lorentz, Cauchy, and Maxwell distributions. Numerical results for the dispersion relation of a Lorentzian plasma are obtained for the whole range of frequencies and for several values of the particle density, the plasma temperature, and the negative ion concentration.
Comments on Paper by A. Manoogian: Interpretation of Ti3+ Electron Spin Resonance Spectra in Alums
Authors: Dionne Gerald F.
Published: April 2011

The argument that Ti3+ ions produce 12 magnetic complexes when substituted for Al3+ in CsAl (SO4)2∙12H2O (Cs alum) is supported neither by experimental evidence nor a realistic physical model. The uniform intensity of the superhyperfine structure in Rb(TiAl) alum disproves the idea that titanium nuclei are involved because the natural abundance of nuclear magnetic isotopes is only 13%. In addition, the magnitudes of the splittings are too small to represent electron–nuclear spin interactions within the Ti3+ ions.
Transition Radiation from a Plasma Boundary
Authors: Seshadri S. R.
Published: April 2011

The transition radiation emitted by a point charge moving with a uniform velocity across a plane interface separating a half-space of plasma from another half-space of free space is investigated. The transition radiation is partly in the form of space waves and partly in the form of surface waves. The characteristics of these waves are discussed with the help of some typical numerical results. The surface-wave power is shown to be many orders larger than the space-wave power and near the surface-wave resonant frequency an increase in the particle velocity is found to decrease the surface-wave power.
Elastic and Plastic Anisotropy of White Tin
Authors: Brar N. S. , Tyson W. R.
Published: April 2011

The effect of elastic anisotropy on the modes of plastic deformation of white tin is studied. The shear modulus for [Formula: see text] slip decreases markedly with temperature, and this is reflected in calculations of the ideal strength, dislocation strain energy, and lattice friction stress. Predictions of relative ease of slip are in broad agreement with experiment, although experimental data is scattered and incomplete.
Binding Energy of Neutron Star Matter
Authors: Ellis Dale , Sprung Donald W. L.
Published: April 2011

The energy per particle of neutron star matter is calculated using reaction matrix elements deduced from Reid's potential. These are parameterized so that the calculation is presented in a simple form. A maximum concentration of nearly 9% protons is found at about twice normal nuclear matter density.
Spurious Structure from Approximations to the Dyson Equation
Authors: Blomberg Clas , Bergersen Birger
Published: April 2011

The method of calculating electron spectral properties by substituting perturbation theoretic results for the self-energy into the Dyson equation is investigated for a model of a deep electron level in which exact results are known. The method gives wrong results in the most important range and also predicts spurious structure. On the other hand, if a perturbation expansion is made directly for the spectral function after extracting the appropriate energy shifts no such difficulty arises.
Measurement of Stopping Powers for 4He, 16O, and 35Cl ions at ~1 to ~3 MeV per Nucleon in Ni, Ge, Y, Ag, and Au
Authors: Ward D. , Graham R. L. , Geiger J. S.
Published: April 2011

Stopping powers have been measured for 4He, 16O, and 35Cl ions at energies of ~1 to ~3 MeV per nucleon in Ni, Ge, Y, Ag, and Au foils. The absolute accuracy is of the order of ± 4%. The results are compared with the semiempirical values tabulated by Northcliffe and Schilling and with previous experimental values.
Umklapp in the Electrical Resistivity of Alkali Metals
Authors: Black J. E.
Published: April 2011

The contribution to electrical resistivity by Umklapp processes is calculated for lithium, sodium, potassium, and rubidium under conditions of constant volume and constant (zero) pressure for temperatures ranging from 0 °K to the melting point.
Electromagnetic Wave Propagation Along a Buried Insulated Wire
Authors: Wait James R.
Published: April 2011

Propagation along a thin dielectric coated wire parallel to the interface between two homogeneous half-spaces is considered. The solution accounts for the presence of the interface provided the coating radius is small compared with the distance to the interface. The final results are simplified in form when dealing with long insulated antennas buried in the earth and operating at low frequencies. Some numerical data are provided for a representative set of conditions. It is found that the presence of the air/earth interface will modify the propagation constant; in some cases the attenuation rate may be increased over that for an infinite medium.
Dynamical Properties of the Three-Dimensional XY Model. II. Singularity Structure of the Frequency Dependent Susceptibility
Authors: Mattingly S. R. , Betts D. D.
Published: April 2011

Twenty coefficients are presented in the exact high frequency, high temperature expansion of the perpendicular susceptibility of the spin-1/2 XY model on the f.c.c. lattice. Padé approximant analysis reveals a weak high frequency, temperature independent singularity at ω ≈ (14 ± 2)J/h which we identify with a "quasi-atomic" resonance at ω = 12J/h. We also find a strong singularity at a lower frequency which decreases with decreasing temperature, and for which we have not yet found a satisfying explanation.
New Configurations in Triply Ionized Indium(In IV)
Authors: Bhatia Kuldip S. , Jones W. E. , Crooker A. M.
Published: April 2011

The emission spectrum of triply ionized indium has been photographed over a spectral range from 340 to 7000 Å using disruptive electrodeless discharge and spark in helium sources. In addition to corrections and revisions of previous analyses, new configurations have been identified. The analysis is extended to include terms belonging to 4d95d, 4d85s2, and 4d9ns (n = 5, 6, and 7). Tentative values are given to several levels of 4d85s5p, 4d94f, 4d96p, and 4d96d. Houston's theory of intermediate coupling has been applied to 4d9ns terms. The double limit of In IV is calculated from the 4d9ns series. In all, 67 energy levels have been established to classify a total of 340 lines.
Resonances in the 15N(α,γ)19F Reaction Between Eα = 1.68 and 2.72 MeV
Authors: Rogers D. W. O. , Beukens R. P. , Diamond W. T.
Published: April 2011

Using the 15N(α,γ)19F reaction, the properties of 6 levels between 5.3 and 6.2 MeV in 19F have been studied. In conjunction with previously reported restrictions on spins for these levels, measurements of branching ratios, radiative widths, and angular distributions have been used to make the following spin–parity assignments; 5618 keV, 3/2−; 5938 keV, 1/2+; 6070 keV, 7/2+; 6088 keV, 3/2−; 6160 keV, 7/2−. The properties of these levels and that at 5336 keV have been compared in detail to the various shell model calculations done for 19F. The properties of the third Jπ = 7/2+ level at 6.07 MeV can be used to clear up some of the confusion caused by the first two Jπ = 7/2+ levels in 19F and the properties of the Jπ = 3/2− levels confirm the fact that the weak coupling model does not explain the negative parity states outside the K = 1/2− band.
Density Dependent Potentials in Simple Liquids
Authors: Egelstaff P. A. , Wang S. S.
Published: April 2011

The density dependence of effective pair potentials may be studied through the density dependence of the liquid structure factor. For a liquid alkali metal (Rb) it is suggested that the ρ1/3 behavior of the Fermi wave-number of the electron gas explains the ρ1/3 behavior of the liquid structure factor recently discovered by Egelstaff et al. For the Lennard-Jones fluid and for liquid neon it is suggested that a near ρ-independent potential gives rise to ρ-dependent changes in the liquid structure factor corresponding to changes in the number of nearest neighbors in real space. This suggestion is tested by comparison with experiment.
Dimer Concentrations in Supersonic Free Jets
Authors: Yealland R. M. , Deckers J. M. , Scott I. D. , Tuori C. T.
Published: April 2011

Measurements have been made of the concentration of dimers produced during the expansion from a supersonic nozzle. The gases studied were: Ar, N2,O2, CO, CO2, C2H4, and N2O. It is shown that an effective specific heat ratio of the expanding gas offers a means of correlating the dimer concentration in terms of the source gas pressure and temperature. The two nozzles employed had opening diameters of 0.14 mm and 0.065 mm. An attempt to obtain a universal dependence for all gases in terms of reduced source parameters was partially successful. Source temperature was varied between 90 °K and 295 °K.