bluuebunny/crossref_metadata_2025 huggingface dataset:
Generalized turbulence space-correlation and wave-number spectrum-function pairs
Authors: Shkarofsky I. P.
Published: April 2011

A new generalized pair of space-correlation and wave-number spectrum functions, which has properties indicated by fluid dynamics and by intuition, is proposed. In contrast with previously used combinations, both are analytic functions and smooth and cover the complete range of their arguments. For example, the spectrum form can apply to all wave numbers rather than to any limited portion, such as the inertial range. Whenever convolution is necessary, it becomes a routine computer calculation. Furthermore, the correlation function has a zero first derivative and a negative second derivative at the origin, giving both an integral scale and a microscale for the turbulence. The spectrum function can have an inertial region with some power-law decay for intermediate wave numbers and has an exponential decay for very large wave numbers. There are three adjustable parameters, determined by experiment, namely, the spectral power-law decay index, the turnover point where this power law starts, and the turnover point where the power dependence changes to an exponential decay. A library of such spectrum functions is not required, since the single proposed function, with its adjustable parameters, can be made to fit most data. One can also allow any even power of wave number for the spectral dependence in the limit of zero wave number. Simple anisotropic functional forms can readily be incorporated. It is indicated that two inertial falloffs with different power laws can be provided and the resultant correlation function is derivable by convolution. The results are applied to simplified versions of plasma electron density fluctuations and to velocity fluctuations of the background fluid. Various scales of turbulence and the related pressure-correlation function are derived. Expressions of correlation functions of amplitude and phase over parallel-line-of-sight propagation paths are also deduced.The proposed pair of functions should only be considered as a generalized model of Tatarski's form, which allows easy conversion from the correlation to the spectrum function and vice versa. Perhaps even more realistic forms can be invented.
An improved theory of gravitation. Part I
Authors: Rastall Peter
Published: April 2011

A theory of gravitation is developed from assumptions that differ as little as possible from those of special relativity and the Newtonian theory of gravitation. As in special relativity, one assumes the existence of preferred coordinate systems (Newtonian charts) in which the nondiagonal components of the metric vanish, and in which the spatial, diagonal components are equal. The metric is determined by a single real function, the gravitational potential, which is assumed, as in the Newtonian theory, to be arbitrary to the extent of an additive constant. A uniqueness theorem is proved for Newtonian charts, and the functional dependence of the metric on the gravitational potential is determined (apart from two constants, which are later fixed by requiring that the equations of motion of a particle have the correct, nonrelativistic limit, and that the potential due to a fixed particle have the Newtonian form at great distances). By a simple change in the units of space and time, the geometry is made Minkowskian. A similar change in the units of mass makes the theory formally similar to special relativity. Particle dynamics is developed. The red shift and the deflection of light by a star are calculated, and agree with the Einstein results. The combination of the assumptions that the potentials due to particles are additive and that the potential due to a fixed particle is not proportional to 1/r, is shown to lead to difficulties. The weight of a simple system is found to be proportional to its total energy, including its gravitational interaction energy. Continuous, static mass distributions are considered. A field equation is derived for the static gravitational potential, and an expression for the energy density of the static gravitational field. The field equation is modified by assuming that the gravitational energy density is itself a source of the gravitational potential. The potential due to a static, spherically symmetric body is calculated, and the perihelion advance of a planet is found to be 11/12 of the Einstein value, in good agreement with the results of Dicke.
High energy levels of 144Nd excited in the decay of 144Pm
Authors: Barrette J. , Monaro S. , Santhanam S. , Markiza S.
Published: April 2011

Gamma–gamma coincidence measurements, carried out with a 7.6 cm × 7.6 cm NaI(Tl) crystal and a 30 cm3 Ge–Li detector, have been performed to look for excited states in 144Nd higher than the known level at 1789 keV. These measurements definitely establish the existence of a level at 2093.11 keV and suggest the placing of another level at 2204.74 keV. Furthermore, an E3 transition deexciting the 1510.14-keV level seems to be present.
Transformation of spin coordinates and the solution of the spin Hamiltonian for an orthorhombic paramagnetic center in a rigid lattice
Authors: McClung R. E. D.
Published: April 2011

The analysis of many spin problems is greatly simplified by the use of coordinate transformations prior to quantization of the spin operators. To illustrate the use of these transformations, the eigenvalues and eigenvectors are obtained for the spin Hamiltonian describing an electron spin [Formula: see text] interacting with a single nuclear spin I in an orthorhombic magnetic environment.
Continuum eigenfunctions for a hard-sphere gas
Authors: Rahman M. , Sundaresan M. K.
Published: April 2011

The singular integral equation resulting from the linearized Boltzmann equation for a hard-sphere gas in the continuous region is reduced to two Fredholm equations of first and second kinds using the theory of singular integral equations with Cauchy-type singularities.
A new band system of copper hydride in the far ultraviolet
Authors: Ringström Ulf
Published: April 2011

The absorption spectrum of CuH has been studied in the region 2270–2740 Å. The lines can be grouped into 22 bands of a 1Σ+–1Σ+ transition, involving the vibrational levels ν = 3,4,..., 11 of the excited state, E1Σ+.In the E1Σ+ state the molecule has a large internuclear distance and an anomalous dependence of the vibrational quanta and the rotational constants on the vibrational quantum number. E1Σ+ resembles the first excited states of the alkali hydrides in which the anomalous behavior is caused by an interaction with an ionic state.There are numerous perturbations by a 3II state. Rough values for the rotational constants, the spin–orbit coupling constant, and the zero positions of two vibrational levels of this state have been estimated from the positions of the perturbation maxima.
Fission of Ag and Br nuclei in 20 GeV/c proton interactions
Authors: Deka G. C. , Deka K. C.
Published: April 2011

In the analysis of a sample of 1424 stars produced in nuclear emulsion by 20 GeV/c protons, 107 stars are found to contain short dense tracks, which have been interpreted as due to nuclear fission. The mean range and velocity of the fission fragments are estimated to be ~9.9 μ and ~0.047 c respectively, compared with ~4.8 μ and ~0.026 c respectively for the residual recoils of ordinary stars. The average space angle between the products of binary fission is found to be 128°.
Lifetime of the 267-keV state in 93Zr
Authors: Prestwich W. V. , Arad B. , Boulter J. , Fritze K.
Published: April 2011

The lifetime of the 267-keV state in 93Zr has been determined by delayed coincidence studies using scintillation detectors. The value measured is T1/2 = (1.45 ± 0.05) × 10−9 s. The B(E2) value for this transition is approximately equal to that for the one-phonon ground-state transitions in 92Zr and 94Zr. This result indicates that the 267-keV level is probably a member of a core-excitation multiplet.
The thermal neutron activation cross section of 59Co
Authors: Merritt Janet S. , Green R. E.
Published: April 2011

The 2200 m/s neutron activation cross section of 59Co has been determined with respect to 197Au by irradiating gold and cobalt foils in a thermal neutron flux. The result for the production of 5.261-year 60Co both directly and through 60Com is[Formula: see text]based on a value of σ0 = 98.7 b for, 197Au. Allowing for the 60Com that decays directly to levels in 60Ni yields a value for the 2200 m/s capture cross section of[Formula: see text]The standard deviation of the mean value of seven determinations was ± 0.06 %. The quoted error of ± 0.27 b has been derived from estimates of systematic errors that are discussed.
Comment on paper by Bhartendu, "A study of atmospheric pressure variations from lightning discharges"
Authors: McCrory R. A. , Holmes C. R.
Published: April 2011

Bhartendu uses two types of microphones to provide the time series for his power spectral investigations of thunder, the hot wire microphone and a wide-range crystal microphone with amplification provided by a sound-level meter. He then takes power spectra calculated from these time series and states conclusions regarding the power spectrum of thunder. Data and discussion are presented here to demonstrate that one cannot use a single-grid hot-wire microphone for power spectral analysis without introducing spurious spectral components.
Toller pole parameters in Δ++(1236) production at high energy
Authors: Nath L. M. , George David J.
Published: April 2011

We have attempted to fit the experimental data on Δ++(1236) production by using the expression derived previously by Nath and Korthals Altes based on 0(3, 1) symmetry and the concept of Toller poles. We show that the fitted parameters have the interesting property that the j0 = 0 and the j0 = 1 residues are equal when expressed in units of the pion mass.
The dipole moment of water in the first hydration shell of a monovalent ion
Authors: Ross Dieter K.
Published: April 2011

The mean dipole moment of the water molecules in contact with a monovalent ion is estimated. The first hydration shell of a spherical ion is assumed to contain either four or six coordinated water molecules, while the water molecules outside this shell are replaced by a continuous medium whose dielectric constant is that corresponding to bulk water at 25 °C. It is found that the dipole moment induced in the attached water molecules is comparable with its permanent dipole moment.
The Shubnikov – de Haas effect in dilute lead-in-bismuth alloys
Authors: Woo On-Ting , Balcombe R. J.
Published: April 2011

The differential Shubnikov – de Haas effect has been studied in samples of bismuth containing up to 50 parts per million of lead. The results indicate that the only effect of alloying on the band structure of bismuth is to shift the Fermi energy; the sizes of the various pieces of the Fermi surface are changed, but their shapes are not distorted. The ratio of the change in net carrier concentration to the concentration of lead atoms is found to be only 0.4, which is anomalously low, compared with values of about 1.0 found for dilute alloys of other metals in bismuth.
Influence of modulus on the magnetic effect in a short-range ordered alloy
Authors: Karim Anwar-ul
Published: April 2011

Thermally activated motion of jogged screw dislocations has been used as the rate controlling mechanism in creep. Apparent activation energies for creep in a Fe – 7.5 at. % Si alloy have been experimentally determined by the temperature cycling technique over both the ferromagnetic and the paramagnetic temperature ranges. The result shows that there is a sudden change in the free energy of activation for self-diffusion at the Curie temperature and this is in agreement with a similar change in Young's modulus.
Theory of spin–lattice relaxation in anharmonic crystals
Authors: Kranendonk J. Van , Walker M. B.
Published: April 2011

The theory of nuclear quadrupole spin–lattice relaxation in anharmonic crystals is developed, both in terms of ordinary perturbation theory and in terms of phonon Green functions. The important relaxation processes are shown to be the direct, first-order Raman, and anharmonic Raman (aR) processes. The aR process is a second-order process due to a combination of the linear spin–lattice coupling and the cubic anharmonic lattice forces, and can be interpreted as arising from the second-order self-energy term in the single-phonon Green function. The effect on the relaxation of the higher-order phonon self-energy and lifetime effects is investigated and shown to be of minor importance. A new method of treating polarization mixing in the Dyson equation for the phonon Green functions is presented. The theory is applied to nuclear quadrupole relaxation in alkali halide crystals and the aR process is shown to be dominant. Nuclear electric dipole and electron paramagnetic relaxation are also discussed.
Discrete relaxation modes for a hard-sphere gas
Authors: Rahman M. , Sundaresan M. K.
Published: April 2011

The discrete spectrum of a linearized Boltzmann equation for a hard-sphere gas is studied, and the results of Kuščer and Williams (1967) for a spherically symmetric state are rederived by a more elementary method. Extension is made to nonisotropic states, and it is shown that the discrete spectrum is empty for [Formula: see text].
Generalized superconvergence relations for KN and scattering
Authors: Vasavada Kashyap V.
Published: April 2011

Generalized superconvergence relations for KN and [Formula: see text] scattering are used to deduce parameters of the rho meson trajectory. Results are found to be in reasonable agreement with those from previous analyses using different methods.
Characteristics of particle production in the interaction of 22.8 GeV/c protons with light nuclei in emulsion
Authors: Bhowmik B. , Shivpuri R. K.
Published: April 2011

The present work is aimed at the study of the characteristics of particle production in interactions between proton and light nuclei. The features studied are angular distribution, inelasticity, transverse momentum, and center-of-mass momentum of the secondary particles. In order to determine the contribution of multinucleon collisions, the results have been compared with those of proton–nucleon interactions. It has been found that, whereas the features of low-multiplicity events closely resemble the similar events from p–N collisions, those of high-multiplicity events are somewhat modified by the occurrence of intranuclear interactions.
Hall effects on thermal instability in a rotating layer of a conducting fluid
Authors: Rai Lajpat
Published: April 2011

This paper discusses the effects of Hall currents on the convective instability of a rotating layer of a conducting fluid in the presence of a vertical magnetic field. It is found that the Hall currents are always destabilizing in the absence of rotation but tend to stabilize the flow as soon as the rotation exceeds certain limits. An analytical condition for nonexistence of overstability is also derived.
Dipole radiation in a periodically stratified medium
Authors: Casey K. F.
Published: April 2011

A formal, exact solution is obtained for the electromagnetic field radiated by a dipole antenna of electric or magnetic type oriented normal to the striations of a periodically stratified dielectric medium of fairly arbitrary profile. The scalar potential functions appropriate to each excitation are evaluated asymptotically by the saddle-point technique. The case of magnetic dipole excitation of a sinusoidally varying medium is studied as an example. It is found that, for frequencies greater than some minimum value, the emitted radiation is characterized by the presence of caustic surfaces which confine most of the radiated power in the broadside direction. The caustics increase in number and colatitude angle with increasing frequency.
Gravitational instability with Hall effect in a plasma
Authors: Sen Amiya K. , Chou Chih Kang
Published: April 2011

It is shown that the new modes introduced by the inclusion of the Hall effect in the gravitational stability problem of a plasma are stable. However, an old mode (which is stable in the absence of a Hall current) becomes unstable. We conclude that the Hall current has a destabilizing effect and that the Jeans criterion for stability is adversely affected by its presence. However, the growth rate of the Hall instability is found to be negligible for any astrophysical system.
Cancellation of the orthogonality charge from the structure-dependent energy of a metal
Authors: Ballentine L. E.
Published: April 2011

The orthogonality charge is defined as the difference between the square of the true wave function and the wave function of the pseudopotential equation. It is shown that the various contributions of the orthogonality charge to the structure-dependent energy of a metal can be grouped so that they cancel out of the final result. Several papers in the literature dealing with ion–ion potentials, crystal structures, or phonon frequencies have not included all of these contributions.
Performance of an electrodeless conductivity probe in anisotropic plasma
Authors: Savic P. , Stock F. T. , Goldman T. J.
Published: April 2011

Following the method of an earlier paper, Maxwell's equations for the magnetic field of a filamentary coil around an infinite circular cylinder of plasma under the action of an axial magnetic field have been solved, and the resulting integral transforms representing the complex coil impedance evaluated on a digital computer. For experimental confirmation, a cylinder of phosphorus-doped silicon was used with a short coil wound around it, and the impedance change of this was determined as a function of the app led axial magnetic field. These impedance changes were used to deduce values of longitudinal conductivity and Hall coefficients of the cylinder were determined, in agreement with estimated values for the solid core.
Optical model analysis of elastic scattering of 100-MeV protons from light nucle
Authors: Li T. Y. , Mark S. K.
Published: April 2011

Elastic scattering cross sections for the interaction of 100-MeV protons with 6Li, 7Li, 9Be, and 12C have been analyzed using the optical model. The experimental differential cross sections are reasonably reproduced. It has been found that no average set of geometrical parameters can provide a quantitative fit to the experimental data for all of these light nuclei; they must be treated individually, with optimum optical potential parameters fluctuating from one nucleus to another. Other features revealed in this analysis include: (1) the spin–orbit radius parameter is smaller than those of the real and imaginary parts of the potential, (2) surface and volume absorption potentials give equally good fit to the experimental results, (3) the radius parameters of the real and imaginary potentials differed from each other, and (4) the radius parameter of the real part of the potential is larger than those used for heavy nuclei.
Transverse momentum distribution of pions in two and six prong events from π−–p collisions at 7.0 GeV/c
Authors: Ijaz M. A. , Campbell J. E. , Naeem A.
Published: April 2011

We have measured the transverse momentum distribution (pt) of the pions produced in the BNL 80″ liquid hydrogen bubble chamber. The bubble chamber was exposed to a 7.0 GeV/c negative ipon beam. We have measured 1000 two prong and 2000 six prong events. The pt distribution for low multiplicity events represents production process via peripheral interactions whereas most of the high multiplicity events may correspond to collisions with large four momentum transfer to the nucleon. The p1 distribution of the pions has been fitted with an expression in the Hagedorn model forp,. The effective temperature obtained from a least square fit of the pion pt distribution for the two and six prong events is 132 ± 9 and 120 ± 3 MeV respectively. If we are justified in analyzing the pt distribution of the low multiplicity events with the Hagedorn model, we find that there is no significant difference in the temperature of the 'peripheral' and 'central' region of the interaction volume. The temperature increases with an increase in the energy of the interaction.
Calculation of anisotropic photoionization cross sections. I. Hydrogen atom
Authors: Lin Sheng Hsien
Published: April 2011

The differential and total cross sections of photoionization of the hydrogen atom from the states 1s, 2s, 2pm, 3pm, 3dm, and 4dm are calculated for the photoelectron kinetic energy E from E = 0.01 atomic unit to E = 2.00 atomic unit. It is found that when the magnetic sublevels of the initial state are equally populated, the angular distribution of photoelectrons has the behavior[Formula: see text]and, besides 1s and 2s states, the angular distribution of photoelectrons from np state, nd state, etc. will become isotropic at a particular photoelectron kinetic energy. The angular distribution of photoelectrons for the case in which the magnetic sublevels of the initial bound state are unequally populated is also discussed.
Electroreflectance of InAs
Authors: Kwan Clarence C. Y. , Thompson Alan G. , Woolley John C.
Published: April 2011

Electroreflectance measurements with the electrolyte technique have been made on various p-type and n-type InAs specimens. The behavior of the spectra and the changeover from p-like to n-like characteristics of the n-type specimens has been studied for various carrier concentrations, electrolytes, and d.c. biasing voltages. The E1 transitions of GaxIn1−xAs alloys close to InAs have then been remeasured and a parabolic variation of E1 and E1 + Δ1 with x obtained.
Hexadecapole deformation in the nuclear 2s–ld shell
Authors: Turner R. J. , Trainor L. E. H.
Published: April 2011

It is shown that the 5/2+ spins of the ground states in 25Al and 25Mg are evidence for hexadecapole contributions to the Nilsson model for the self-consistent field.
Ranges of nitrogen ions in Al, Ni, Ag, and Au
Authors: Nakata Hiroshi
Published: April 2011

Energy loss curves for 14N ions passing through Al, Ni, Ag, and Au have been observed at E(14N) = 1–12 MeV, and the range–energy relations have been obtained. The present results are a little lower than the theoretical values. This is partly due to the fact that the parameters k and μ are large in these cases.
Properties of the 4.038 MeV state in 25Al
Authors: Röpke H. , Anyas-Weiss N. , Litherland A. E.
Published: April 2011

The 4.038 MeV state in 25Al, which is also the Ep = 1.824 MeV resonance in the 24Mg(p,γ) reaction, has been investigated using the 24Mg(p,y) reaction. The γ-ray decay scheme is given and a limit of [Formula: see text], is obtained for the inelastic proton scattering width. Angular distribution measurements of deexcitation γ rays confirm previous values of radiation mixing ratios, but cannot remove the Jπ = 9/2+, 5/2+ ambiguity in the spin–parity assignment. A Doppler shift attenuation measurement of the4.038 MeV deexcitation γ ray yields ƒ(τ) = 0.91 ± 0.02, corresponding to a lifetime of τ(4.038) = 22 ± 6 fs. The particle widths are derived using the lifetime and a previous measurement of the γ-ray yield at the 24Mg, Ep = 1.824 MeV resonance. On the basis of the particle width, arguments are given for a Jπ = 9/2+ assignment to the 4.038 MeV state.
Light scattering by phonons in the presence of a heat flow
Authors: Griffin Allan
Published: April 2011

If the temperature in an insulating crystal decreases in the z-direction, there are more phonons with momentum qz > 0 than with qz < 0. The resulting difference between the Stokes and anti-Stokes Brillouin intensities is proportional to the mean free path of the phonon involved and to the temperature gradient. The effect should be observable by either neutron or photon scattering.
Heat capacities of O2, N2, CO, and NO at low temperatures
Authors: Burford J. C. , Graham G. M.
Published: April 2011

The heat capacities of O2, N2, CO, and NO have been measured in the temperature range from 4.2 °K to about 0.8 °K. No anomalous behavior was found. The results were fitted to the Debye expression (assuming 3 degrees of freedom per molecule) to yield the following values for Θ0: O2, 104.5 ± 1.0 °K; N2, 83.5 ± 1.0 °K; CO, 103.0 ± 1.0 °K; NO, 122 ± 2 °K. The results are discussed in terms of the residual entropies of CO and NO.
Intraband Faraday and Voigt effects in lead telluride
Authors: Chandler K. K. , Wallace P. R.
Published: April 2011

The Faraday and Voigt coefficients—rotation of the axis of polarization, and the ratio of minor to major axis of the elliptically polarized transmitted wave—have been calculated at frequencies up to and beyond the intraband plasma frequency, and for magnetic fields up to 120 kG. The behavior of these coefficients is simply related to the spectrum of normal modes of the coupled system of electrons, ions, and electromagnetic fields.
Application of the nonuniform-field treatment to the infrared properties of LiF
Authors: Beaulieu A. J.
Published: April 2011

The "nonuniform-field treatment" developed earlier for infinitely thick crystals is applied to the LiF crystal. Comparison with experimental results both at 45° and at small angles of incidence gives good quantitative agreement only when the ratio of the longitudinal optical frequency to the transverse optical frequency is assumed to be 1.7 instead of 2.2 as predicted by the Lyddane–Sach–Teller relation. An extension of the treatment to thin films is presented and the comparison of the results with Berreman's experimental values indicates that the asymmetry and the amplitude of the features which could not be explained before can be predicted in terms of the nonuniform-field treatment, again provided the optical phonon frequency ratio is 1.7.
Perturbation theory of fluids and deviations from classical behavior
Authors: Kim S. , Henderson D. , Barker J. A.
Published: April 2011

The effects of quantum deviations from classical behavior of simple fluids are examined using the recently developed perturbation theory of fluids. The free energy is expanded in powers of Planck's constant and in powers of the strength of the attractive potential about an unperturbed system of hard spheres whose diameter is chosen to take into account the softness of the repulsive potential. Using the 6:12 potential, the theory is applied to gaseous helium and hydrogen with good results, and to liquid neon with satisfactory results.
A finite formulation of perturbative field theory
Authors: Eoll Christopher K.
Published: April 2011

A formalism is set up for obtaining the perturbative S-operator for an arbitrary field theory, "renormalizable" or "nonrenormalizable". Ultraviolet divergences never appear. The basic assumptions of the theory are Bogoliubov causality and TCP invariance of the S-operator. Interpolating fields are never used.In this formalism, calculations are based on a uniqueness theorem, rather than on an explicit prescription for the coefficients in the normal expansion of the S-operator. However, there is manifest Lorentz covariance at each stage of the calculations. Boundary conditions are considered in some detail.Example calculations using the present formalism are carried out for the [Formula: see text] theory and for the Fermi interaction involving the muon, electron, and neutrinos. Third- and even fourth-order perturbative results can be obtained without great difficulty, at least for cubic interactions.
Spin effects in pion charge-exchange scattering on nuclei
Authors: Charlton Lowell , Eisenberg J. M.
Published: April 2011

The differential cross section for pion charge-exchange scattering from 12C is calculated using sum-rule techniques in order to investigate possible spin-dependent effects in proton–neutron correlations. The resulting cross section proves to be quite insensitive to such effects under the usual assumptions concerning the correlation function.
Fine structure in the region of symmetric mass distribution for cumulative fission yields
Authors: Thind K. S. , Tomlinson R. H.
Published: April 2011

It is predicted that there should be fine structure in the cumulative mass yield curve in the symmetric mass region where major discontinuities in the neutron emission vs. mass curve exist. In the case of low-energy neutron fission of 238U, this fine structure takes the form of a pronounced depression in the region of mass 125. Under similar conditions for 232Th, the fine structure may take the form of depressions in the region of mass 110 and 125 so that the cumulative mass yield curve appears to have a central peak.
Thermodynamic properties of crystalline NaCl
Authors: Kwon T. H. , Henkel J. H.
Published: April 2011

The pair model is introduced in the lattice dynamics to obtain normal mode frequencies for crystalline NaCl. By means of the direct summation over the N normal mode frequencies allowed in the first Brillouin zone, the thermodynamic functions of crystalline NaCl are evaluated, and the convergence of these functions with respect to N is examined as N is allowed to approach infinity. Rapid convergence is obtained for temperatures ranging up to the melting point, and the converged results are compared with the experimental data along with the calculations by others. The results indicate that the direct summation over the normal mode frequencies in the first Brillouin zone is a much more practical method of evaluating the thermodynamic functions than is the customary procedure involving integration over the frequency spectrum.
Magnetic susceptibility of Mn2P2O7
Authors: Fowlis D. C. , Stager C. V.
Published: April 2011

The susceptibility of Mn2P2O7 has been measured from 4.2 to 300 °K. Mn2P2O7 is antiferromagnetically ordered below 14 °K with a spin direction in the ac plane at an angle of 22° to the a axis. A simple calculation of the anisotropy energy fails to predict the spin direction.
Excitation function of the N2+ Meinel band by electron impact
Authors: Srivastava B. N. , Mirza I. M.
Published: April 2011

Excitation cross sections of the N2+ Meinel bands by electron impact have been determined and are compared with the theoretical values obtained from the Franck–Condon factors of the excitation.
Paramagnetic impurities in an itinerant antiferromagnet. Theory
Authors: Behera S. N. , Viswanathan K. S.
Published: April 2011

The effects of 3-d paramagnetic impurities in an itinerant antiferromagnetic metal are investigated using the Wolff–Clogston model. The changes in the Néel temperature TN, the energy-gap parameter, and the density of states are evaluated in the Hartree–Fock approximation and in the lowest order in the impurity concentration. The results on the changes in TN are compared with the experimental findings on V, Mn, Fe, Co, Ni, Mo, and W impurities in chromium. The agreement between theory and experiment suggests that the changes in TN are essentially due to three mechanisms: (a) the effect due to changes in the electron–atom ratio, (b) the spin-dependent scattering due to paramagnetic impurities, and (c) the changes in the intra-atomic coulomb potential at the impurity site. In the case of Mo and W, the last effect explains the observed decrease in TN in Cr.
Summary of experimental verification of the flux and energy spectrum of secondary electrons at high altitudes in the atmosphere
Authors: Verma Satya Dev
Published: April 2011

A brief summary of the measurement of the flux and energy spectrum of secondary electrons at balloon altitude over Fort Churchill is given. These measurements are compared with two calculations, one by Perola and Scarsi and the other by the author. A correction is made to an error of Beedle and Webber in plotting the results of the author's calculations.
Phonon-assisted absorption in crossed electric and magnetic fields in direct-band semiconductors. II
Authors: Batra I. P.
Published: April 2011

In polar semiconductors with direct energy gaps, optical absorption is observed for photons with energies well below that corresponding to the energy gap. It is now established that the absorption tail (Urbach's law) is due to indirect phonon-assisted optical transitions involving the absorption of one or more optical phonons of energy kΘ. In the present paper we have considered the effect of crossed electric and magnetic fields on the optical absorption in that region of the Urbach tail where second order processes are dominant. The experimentally favorable situation involving a weak electric field is investigated. A new perturbation expansion in terms of a dimensionless parameter is developed in this connection and is used to obtain the weak electric field limit. Such a study may be useful in exploring the Landau level structure of the valence and conduction bands separately.
Linearly polarized monochromatic radiation from a water-vapor laser at 118.6 microns
Authors: Brannen Eric , Hoeksema Maaike , Sarjeant W. J.
Published: April 2011

A water-vapor laser has been operated in the far infrared region with a reflection grating as one end mirror. The radiation was monochromatic at 118.6 μ and strongly linearly polarized. In terms of intensities, the degree of polarization of the laser output was approximately 99.8%.
Immersions of space-time
Authors: Rastall Peter
Published: April 2011

It is shown that space-time can be regarded as a 4-dimensional subspace of a conformally flat, 6-dimensional space, or of a flat, 8-dimensional space. The group of isometries of the tangent spaces of the 6-dimensional space is O(4, 2), which has recently been used to describe elementary particles.
Electron effective-mass values in GaxIn1−xSb alloys
Authors: Aubin Marcel J. , Thomas Mathew B. , Tongerloo Eric H. van , Woolley John C.
Published: April 2011

Room-temperature measurements of Faraday rotation, magneto–thermoelectric power, and infrared reflectance have been made on homogeneous coarsely polycrystalline n-type samples of GaxIn1−xSb alloys produced by the horizontal Bridgman technique. Using these data and a Kane equation for the (000) conduction band, values of the bottom of the band effective mass m00* have been determined over the composition range 0 < x < 0.85, i.e. the range in which the subsidiary [Formula: see text] minima make no contribution. The results from the three different techniques show very good agreement. From the data, values are obtained also for the square of the matrix element P2, the high-frequency dielectric constant ε∞, and the scattering parameter s for the various alloy specimens.
Estimation of number of degrees of freedom of nuclear reaction widths distributions
Authors: Lycklama H. , Kennett T. J. , Hughes L. B.
Published: April 2011

The effects of small sample sizes have been studied in estimating the number of degrees of freedom of nuclear reaction widths distributions using the method of maximum likelihood, the method of moments, and the method of minimization of variance. It is found that the estimates are biased as a function of the sample size and the number of degrees of freedom of the widths distribution. Bias is reduced somewhat by applying the estimation techniques to the finite sample transformation of the chi-squared distribution, the beta distribution. The efficiency of each estimation technique is indicated by comparison of the variances of the estimates to the minimum variance obtainable. A modified maximum likelihood estimator is found to be unbiased and efficient.
CP violation with an intermediate weak vector boson
Authors: Gourishankar Radha , Kamal A. N.
Published: April 2011

A model of CP violation due to the existence of a neutral intermediate weak vector boson is studied. It is found that all leptonic and semileptonic decays are CP conserving; however nonleptonic decays are all CP violating to order [Formula: see text]. The CP-violating decays also preserve the [Formula: see text]. An estimate of the electric dipole moment of the nucleon based on such a model gives μe ≈ 10−29 e cm. The electric dipole moment of the electron is zero.
Atmospheric vertical energy flux due to a ground disturbance
Authors: MacKinnon Robert F.
Published: April 2011

Evaluations are given of the nett mean vertical energy flux due to small oscillations at several altitudes caused by a ground disturbance in a wind- and temperature-stratified atmosphere. A theoretical model is assumed which consists of an inviscid perfect gas above a flat nonrotating earth. Results are given for various wind and temperature profiles. It is found that winds can appreciably affect the energy flux due to long-period waves at great heights. The importance of the temperature structure in the vicinity of critical levels is demonstrated. The significance of 'leaky' modes is discussed with regard to the relationship between the discrete and continuous spectra of waves. A simple approximation to energy flux associated with acoustic waves of short periods is found to apply for certain ground disturbances. The relevance of the results to traveling ionospheric disturbances is discussed.
Levels populated in 193Ir from the beta decay of 193Os
Authors: Price R. H. , Johns M. W. , Ahmed N. M. , Habib E. E.
Published: April 2011

The beta and gamma ray transitions involved in the decay of 193Os have been studied using Ge(Li) and Nal(Tl) detectors and magnetic spectrometers, singly and in coincidence. Fifty-four gamma ray transitions have been observed and all but one classified on the basis of energy fit and β−γ and γ−γ coincidence measurements. The internal conversion coefficients of 25 of the stronger transitions were determined with a magnetic spectrometer operating at a resolution of ~0.1% in momentum, and multipole mixing ratios determined. The energies and spins of levels in 193Ir have been determined as follows: 0 (3/2+), 73.006 (1/2+), 138.887 (5/2+), 142.125 (+), 180.00(3/2+), 357.7 (7/2+), 361.79 (5/2+), 440.95 (+), 460.46 (3/2+), 557.29 (1/2+), 559.22 (5/2+), 660.09 (+), 667.13, 695.06 (3/2+), 712.08 (3/2+), 778.50,784.13, 848.94, 874.45, 891.57.
Triplet-odd nucleon–nucleon interaction and spin-orbit splitting
Authors: Pearson J. M. , Saunier G. , Trudeau F. , Desgrolard P.
Published: April 2011

Three different triplet-odd N–N potentials, all of which have some measure of conformity to meson theory, are shown to lead to approximately correct spin-orbit splittings in several dcs ± 1 nuclei.
Effect of finite ion Larmor radius on the stability of rotating superposed fluids
Authors: Kalra G. L.
Published: April 2011

The effect of finite ion Larmor radius on the gravitational instability of two superposed fluids in uniform rotation is investigated for interchange perturbations, using the macroscopic equations of motion, where the finite ion Larmor radius effect is incorporated through off-diagonal terms in the pressure tensor. It is found that the region of stable wavelengths is enhanced due to the simultaneous presence of finite Larmor radius and a uniform rotation. A similar conclusion is also arrived at for the situation when a vortex sheet is present between the two superposed fluids.
Common approximations in many-body systems
Authors: Revzen M. , Trainor L. E. H.
Published: April 2011

A new way of presenting the random phase and ladder approximations is introduced which provides a convenient, probabilistic classification scheme and makes the fundamental nature of these approximations transparent. The physical interpretation of these approximations is reviewed in the light of this new method of presentation and the natural propagators to be associated with each approximation are discussed.
Diffusion in multicomponent metallic systems. X. Diffusion at and near ternary critical states
Authors: Kirkaldy J. S. , Purdy G. R.
Published: April 2011

The thermodynamics of ternary solutions near critical states is given a new formulation and the inferences for the ternary diffusion matrix are developed therefrom. Recognizing with Onsager that the diffusion matrix is proportional to the product of the mobility matrix and the Hessian of the Gibbs' free energy, it is demonstrated that for all ternary critical states (d2F = d3F = 0) the determinant of the diffusion matrix is stationary and zero while all the elements of the matrix are stationary as well. At a ternary critical point, if it exists, all elements of the matrix are zero.
High temperature dielectric constant of KI
Authors: Chandra Suresh
Published: April 2011

The dielectric constant of KI crystal has been measured at 23.6 GHz from room temperature to near the melting point. A K-band microwave standing wave ratio technique was used for this purpose to avoid complex polarization effects. It was found that the dielectric constant of KI increases more rapidly than for KCl and KBr, presumably due to its larger thermal expansion coefficient at high temperatures.
Cross section for the reaction 16O(γ,n0)15O at giant resonance energies
Authors: Khan T. A. , Hewitt J. S. , McNeill K. G.
Published: April 2011

The cross section for that photoneutron reaction in 16O which leaves 15O in its ground state has been measured for photon energies ranging from 17 to 30 MeV, i.e. at energies corresponding to giant resonance excitations in 16O. Time-of-flight methods, yielding resolutions equal to 100 keV at a neutron energy of 6 MeV, were used to measure neutron spectra emitted at an angle of 98° when targets of ordinary and heavy water were irradiated with pulsed bremsstrahlung. The differential cross section at 22.3 MeV excitation was found to be 1.00 ±.05 mb/sr, assuming a photodisintegration cross section at 98° equal to 55.3 μb/sr (laboratory system) for deuterium, this latter value having been derived from calculations which have been substantiated experimentally to within ± 10%. The results are discussed with reference to other photodisintegration experiments and to recent theoretical work.
Specific heat below 3 °K of a gold–zinc and a gold–indium alloy
Authors: Martin Douglas L.
Published: April 2011

Face-centered-cubic alloys of gold with 10 atomic % zinc (divalent) and 10 atomic % indium (trivalent), respectively, were measured in the range 0.4 to 3.0 °K. The coefficients of the nuclear specific-heat term were 1.80 ± 0.07 μcal °K/g atom for AuZn and 1.29 ± 0.06 μcal °K/g atom for AuIn (95% confidence limits). For a gold–10 atomic % silver (monovalent) alloy (Martin 1968) the nuclear term was 0.44 μcal °K/g atom. These results show that electric field gradients in alloys are not simply proportional to the valence difference of the components, a conclusion which may be drawn from NMR results. For the AuZn alloy the electronic specific-heat coefficient (γ) is 153.4 ± 0.7 μcal/°K2 g atom and the limiting value of the Debye temperature (θ0c) is 177.0 ± 0.5 °K. For the AuIn alloy γ is 185.9 ± 0.7 μcal/°K2 g atom and θ0c is 159.1 ± 0.3 °K.
Crystal dynamics of nickel–iron and copper–zinc alloys
Authors: Hallman E. D. , Brockhouse B. N.
Published: April 2011

Using inelastic scattering of slow neutrons, the frequency-wavevector dispersion relations for the lattice vibrations in the face-centered cubic alloys Ni3Fe, Ni0.5Fe0.5, Ni0.3Fe0.7, and Cu3Zn have been measured at 296 °K. Measurements were also made at 573 °K for the Ni0.3Fe0.7 alloy. The results for the nickel–iron alloys are very similar to those for nickel, with mean frequency ratios (alloy/nickel) of 0.990, 0.950, 0.953 for the Ni3Fe, Ni0.5Fe0.5, and Ni0.3Fe0.7 alloys respectively. Significant deviations of the limiting slopes of the dispersion curves for Ni0.3Fe0.7 from velocities reported by Alers et al. from ultrasonic measurements are thought to be caused by magnetic contributions which are small at the frequencies measured here. The temperature dependence of the frequencies for Ni0.3Fe0.7 is consistent with that observed for nickel. For Cu3Zn, the results are similar to those for copper; except that the mean frequency ratio (alloy/copper) is 0.932. A neutron diffraction method was used to characterize the homogeneity and composition of the alloys. Born – von Kármán fits to the data, the frequency distributions, and Debye temperature vs. temperature relations are also given.
Radiative capture of neutrons by the 5.2 eV resonance in 109Ag
Authors: Ing H. , Gameson J. J. , King J. D. , Taylor H. W.
Published: April 2011

The reaction 109Ag(n,γ)110Ag has been studied through the capture of neutrons by the 5.2 eV resonance in 109Ag. The gamma rays were observed with a 33 cm3 Ge(Li) detector and a 2048-channel pulse-height analyzer. A level diagram spanning the range 0-2 MeV is proposed for 110Ag and compared with the level diagram based on the gamma transitions produced by capture of thermal neutrons. The distribution of partial radiative widths was obtained and was found to be in good agreement with the Porter–Thomas distribution.
Dependence of the r.m.s. nuclear radius on the deformation parameters
Authors: Cusson R. Y. , Castel B.
Published: April 2011

The concept of "nuclear compressibility under deformation", introduced by Fradkin and others in their experimental studies of isotope shifts, is analyzed. It is shown that in the harmonic-oscillator model Fradkin's compressibility parameter ξ can occur in a natural way. Theoretical estimates of ξ are obtained, using spherical and deformed oscillator models, as ξ = −5/4π and −5/16π respectively. They bracket the experimental value [Formula: see text]. Possible improvements of these estimates are discussed.
Electrohydrodynamic instability of a cylindrical viscous jet
Authors: Michael D. H. , O'Neill M. E.
Published: April 2011

The electrohydrodynamic instability to small axisymmetrical surface wave disturbances of a circular, cylindrical, electrically conducting, viscous jet, which is projected along the axis of a circular conducting cylinder, is considered for the cases when the charges or potentials remain unaltered. The discussion given is applicable for arbitrary viscosities and it is shown that points of transition from stable to unstable modes of oscillation, or vice versa, are the same as for the inviscid jet.
Specific heat of pure single-crystal and polycrystalline copper below 3 °K
Authors: Martin Douglas L.
Published: April 2011

Within the error limits of the measurement there is no difference between the specific heats of pure single-crystal and pure polycrystalline copper below 3 °K. It is suggested that previous observation of such a difference was because the single crystal had not been degassed before measurement.
The K-conversion coefficient of the 35.6 keV transition in 115In
Authors: Campbell J. L. , Kirk J. P.
Published: April 2011

The K-conversion coefficient of the 35.6 keV transition in 115In has been re-measured by a coincidence technique employing Ge(Li) detectors. Previous measurements differ widely among themselves, a factor of almost three existing between extreme values. The present result, 8.50 ± 0.35, which is free from many of the uncertainties present in previous work, is slightly lower than the value of 9.2 given by the self-consistent-field calculations of Hager and Seltzer.
Stimulated thermal scattering in isotropic media
Authors: Batra I. P. , Enns R. H.
Published: April 2011

A rigorous theoretical treatment of stimulated thermal scattering for an isotropic medium is presented. A phenomenological damping term is introduced into the electromagnetic field equation and then this equation is simultaneously solved with the equations describing the medium. As the set of equations is nonlinear, the solutions have been obtained under suitable approximations. The implications of these approximations, as far as performing the experiments is concerned, are thoroughly discussed. The nonlinear nature of the problem is responsible for saturation, and the optical-loss term gives rise to depletion. Both these phenomena have been included in our treatment. Whereas the 'saturation' is always present in a real system, 'depletion' can be an important effect in a medium involving a large linear optical absorption coefficient α. The experimental relevance of both these effects is discussed. Furthermore, we have derived the threshold condition on the laser field intensity. In the appropriate limits, our results reduce to those already reported in the literature.
On the propagation of a pulse through an antipode
Authors: Wait James R.
Published: April 2011

The time domain response of the fields in the vicinity of an axial caustic is calculated. The idealized model is a spherical concentric cavity with perfectly conducting walls. It is shown that the transient field, in the vicinity of the antipode of a dipole source, exhibits a strong distortion in the pulse shape.