bluuebunny/crossref_metadata_2025 huggingface dataset:
A Monte Carlo Study of Radiation Trapping Effects
Authors: Williams J. F. , Wang J. B. , Carter C. J.
Published: June 2013

A Monte Carlo simulation of radiative transfer in an atomic beam is carried
out to investigate the effects of radiation trapping on electron–atom
collision experiments. The collisionally excited atom is represented by a
simple electric dipole, for which the emission intensity distribution is well
known. The spatial distribution, frequency and free path of this and the
sequential dipoles were determined by a computer random generator according to
the probabilities given by quantum theory. By altering the atomic number
density at the target site, the pressure dependence of the observed atomic
lifetime, the angular intensity distribution and polarisation of the radiation
field is studied.
Magnetic Behaviour of Systems with a Quasi-doublet Ground State
Authors: Gubbens P. C. M. , Mulders A. M.
Published: June 2013

In this paper we will present a study of several Tm and Pr compounds, where
the rare earth atoms have as their two lowest energy levels a quasi-doublet
ground state. These compounds are also compared with Er and/or Dy
compounds, which have a Kramers doublet as ground state. Four compounds
(TmNi5, TmCu2, TmCuAl and
PrRu2Si2) are discussed in
sequence, where the energy separation of the two levels of the quasi-doublet
ground state doublet is increasing. These compounds were studied with rare
earth Mössbauer spectroscopy and µSR as the main measuring
techniques.
57Fe Mössbauer Experiments of Doped (La0·67Ba0·33)(Mn0·9Fe0·1)O3
Authors: Osthöver C. , Sauer C. , Arons R. R.
Published: June 2013

We report on Mössbauer effect (ME) experiments on the compound
(La0·67
Ba0·33)(Mn0·9
Fe0·1)O3 with the simple
perovskite-like structure in the range from 4·2 to 300 K. From 190 to
300 K the spectra are described by a single quadrupole split doublet with a
total splitting of e2
qQ/2 = 0·38
mms-1. This indicates that the local environment of the
Fe3+ ions is not cubic, in contrast to the X-ray
diffraction result on the same sample. At 4·2 and 25 K complex
hyperfine (hf) split spectra are obtained. At least eight magnetically split
subspectra with different hf fields must be used for describing these spectra
adequately. From about 50 K up to 150 K the ME spectra reflect a relaxation
process, indicating that the Fe moments fluctuate with frequencies in the
range of the Larmor frequency in this temperature range. By describing the
latter ME spectra by a magnetically split six-line spectrum with average hf
fields and strongly broadened linewidths, the Fe moments are found to order
below about 110 K. This value is much lower than the Curie temperature of
Tc = 190 K obtained from
our magnetisation measurements. The fluctuations of the Fe moments observed
down to low temperatures might be responsible for the fact that the
metal-semiconducting transition, which usually occurs at
Tc according to the double
exchange model, is shifted from Tc
= 190 K down to 140 K.
Nuclear Spin-system Dynamics affected by Double Inhomogeneity under Multipulse Excitation in Statistical Tensor Formalism
Authors: Shakhmuratova L. N.
Published: June 2013

New coherent transient effects formed due to double inhomogeneity, i.e.
inhomogeneity in the main precession frequency (Larmor inhomogeneous
broadening) and of the rf amplitude expressed in frequency units (Rabi
inhomogeneous broadening), in˚uencing the nuclear spin- system dynamics
during rf pulse excitation, have been predicted and investigated by use of the
method of concatenation of perturbation factors (CPF) in statistical tensors
(ST) formalism. Multiple pulse excitation under double inhomogeneity is
examined when the repetition period of a pulse sequence is shorter than
T1.
Progress of Electron Momentum Spectroscopy in China
Authors: Chen X. J.
Published: June 2013

Developments in the application of electron momentum spectroscopy (EMS) in
China are described. Particular attention will focus on our progress in
applying various generation EMS spectrometers to atomic and molecular targets
of interest. Results from these experiments are presented.
Helium Double Photoionisation: An Accurate Solution of a Three-body Coulomb Problem
Authors: Kheifets Anatoli S. , Bray Igor
Published: June 2013

We present here the solution of the helium double photoionisation problem by
the convergent close-coupling (CCC) method. This method allows us to obtain
the most detailed description of the double photoionisation process in the
form of the fully resolved triply differential cross section (TDCS). The
accuracy of our model is tested by calculating the TDCS in the three different
forms of the electromagnetic operator which produces essentially identical
results. We compare our calculation with the most accurate experimental and
theoretical data available to date.
Sporadic E Structures and Pressure Oscillations at Ground Level
Authors: Khan MSH
Published: June 2013

This paper describes a method for obtaining rapid measurements of the phase differences between signals from the ionosphere at two pairs of aerials. Measurements were made, during quiet ionospheric conditions, on the first hop near-vertical reflections using a pulsed 1� 98 MHz radiowave transmitter.
OH1667 Line Absorption at 2° <lII <4°, ?0°30' <bII <1°
Authors: McGee RX , Brooks JW , Sinclair MW , Batchelor RA
Published: June 2013

The OH absorption line at 1667 MHz has been traced from III = 2� to 4�15' near the galactic plane. Line profiles and contours of apparent opacity are presented. The measurements have completed the general picture of absorbing hydroxyl gas in the vicinity of the galactic centre and suggest the existence of a gradient of radial velocities of values near -136 km sec-1 at III = 359� to values near + 41 km sec-1 at III = 3�30'.
Australian Journal of Physics Astrophysical Supplement
Authors: Hoskins DG , Murdoch HS
Published: June 2013

The results of the Molonglo fan beam survey are given for the region lOh 30m to ISh 30m and 0� to - 39�. Improved right ascensions and 408 MHz flux densities are given for Parkes sources in the region. Other sources :> 2 flux units are listed with a few sources down to 1� 6 flux units. Oomparisons are made with the Parkes accurate positions.
Cosmological Theory Based on Lyra's Geometry
Authors: Halford WD
Published: June 2013

Using a Robertson-Walker metric in a modified Riemannian manifold, a cosmological theory is obtained which gives rise to nonstatic perfect-fluid world models. The cosmological equations are formally identical to those of the normal relativistic theory with cosmological constant A.
Exact Solution of a One-dimensional Spin System
Authors: Gibberd RW
Published: June 2013

The partition function and the Gibb's free energy are calculated exactly in the thermodynamic limit, using techniques which are well known in the theory of superconductivity. This calculation illustrates explicitly the similarity between the phase transition in superconductivity and the molecular field transitions in spin systems.
On the Validity of the Two-term Approximation of the Electron Distribution Function
Authors: Robson RE , Kumar Kailash
Published: June 2013

The Boltzmann equation for electrons moving in a neutral gas under the influence of an externally applied field is solved by expanding the electron distribution function in terms of Legendre and Sonine polynomials. The solution is given in terms of infinite matrices which have elements ordered by the Sonine polynomial index, and which are dependent upon the field strength. From the structure of the formulae, it is possible to infer that truncation of the Legendre polynomial expansion after two terms is a good approximation at all field strengths. This is supported by calculations of the electron drift velocity at low field strengths, which show that the error introduced by making the two-term approximation is small, even when the deviation from equilibrium is significant. The convergence of the Sonine polynomial expansion is shown to be strongly depende:r;J.t upon field strength, and large matrices are required in the drift velocity formula at even small field strengths.
Generalized Solutions of Steady Crossed-field Magnetohydrodynamic Channel Flows
Authors: Cashman JD
Published: June 2013

Solutions for the flow in an MHD interaction are presented and compared when the fluid is a perfect gas, a singly ionizing monatomic gas, and a gas for which no thermodynamic model is specified. The separate effects of a changing duct area, body force, and addition of heat are presented and interpreted.
The Polarization of Extended Radio Sources at 6 cm Wavelength. I. Extragalactic Sources
Authors: Gardner FF , Whiteoak JB
Published: June 2013

Maps are presented of the linear polarization distributions over eight extragalactic radio sources. They were obtained at 6 cm wavelength with a 4' arc resolution. Low brightness extensions show polarization of up to 70% with magnetic fields aligned perpendicular to their elongations.
Parallel Viscous Modification of the Resistive "Tearing" Instability in a Cartesian Model of the Hard-Core Pinch
Authors: Marinoff GM
Published: June 2013

There is continuing interest in the possibility that a diffuse pinch may be used to achieve plasma containment in the laboratory, and ultimately lead to a successful thermonuclear reactor. Such a system is likely to be stabilized against hydromagnetic modes by strong magnetic field shear, but the question of stability against resistive modes remains. In this note, a Cartesian model is adopted, and the influence of "parallel" viscosity (Stringer 1970) on the resistive "tearing" instability in the hard-core pinch is examined. Previously, purely resistive calculations of growth rates in this configuration have been reported by Hosking (1967) and Lister and Hosking (1970).
2700 MHz Observations of 4C Radio Sources in the Declination Zone +4° to ?4°
Authors: Wall JV
Published: June 2013

Most sources in the 40 catalogue with declinations between +4� and _4� have been observed at 2700 MHz. Accurate positions, flux densities, and the results of a search for optical identifications are presented. A brief comparison is made with results from other investigations.
On the Theory of Anisotropic Diffusion of Electrons in Gases
Authors: Huxley LGH
Published: June 2013

It is now recognized that when electrons move in a steady state of motion in a gas in an electric field the process of diffusion is in general anisotropic with a coefficient of diffusion DL along or against the electric force eE that is not the same as the coefficient D for directions normal to eE. A theoretical discussion of this phenomenon based upon the Maxwell?Boltzmann equation is given which also entails consideration of related matters such as the distribution function for an isolated travelling group, the distribution of number density n, the equation of continuity and current density, and the relation of the theory of the travelling group to that of the steady stream.
Short Communications Relationship Between Es and the Earth's Magnetic Field at Middle Latitudes
Authors: Goodwin GL
Published: June 2013

Attempts have been made, with some success, to find an association between changes in the intensity of Es ionization and in the intensity of the Earth's magnetic field (Wilkie and McNicol 1962; Fatkullin 1965; Goodwin 1965; Ovezgel'dyyev 1965). Nevertheless, the overall results of these investigations have not revealed a consistent relationship between Es and the Earth's field. This is partly due to the fact that daytime and night-time data, or data for the different seasons, were generally not treated separately. In the present paper an analysis of new observations is presented and the results of some previous analyses are also reappraised. A consistent relationship is found between night-time Es observations and the geomagnetic field.
A General Formulation of the Transfer Equation. II. Line Formation with General Redistribution
Authors: Cannon CJ
Published: June 2013

The multidimensional equation of transfer for spectral line radiation under a general redistribution law is studied. It is shown that the equation may be rewritten as a system of equations of the "Feautrier" form, which are known to be exceedingly stable and efficient under numerical reduction. It is also shown that the inclusion of a multidimensional differential macroscopic velocity field does not alter the functional form of the equations obtained and therefore may also be treated by the general Feautrier technique.
Radiation from Accelerated Point Dipoles in Circular and Keplerian Orbits
Authors: Monaghan JJ , Shapcott CM
Published: June 2013

The frequency spectrum of electromagnetic radiation from accelerated magnetic dipoles is computed for circular and Keplerian motion. For circular motion three orientations of the dipole are considered: (1) parallel to the velocity vector, (2) parallel to the radius vector, and (3) perpendicular to the plane of the circle. For Keplerian motion the orientation is taken as perpendicular to the orbit. Expressions that are valid for velocities arbitrarily small and arbitrarily close to the velocity of light are derived. The mean power radiated is determined numerically.
The Redshifts of 27 Radio Galaxies
Authors: Whiteoak JB
Published: June 2013

A series of spectroscopic observations of galaxies believed to be associated with radio sources was carried out with the 74 in. reflector of the Mt. Stromlo Observatory during the period September 1968 to September 1969. As a result, redshifts have been determined for 27 radio sources, the majority of which are located at southern declinations.
Acoustic Radiation Pressure Forces and Torques from Elastic Scattering
Authors: Smith WE
Published: June 2013

A generalized theory of radiation pressure forces for arbitrary non-dissipative acoustic systems is applied to the calculation of the force and torque exerted on a body elastically scattering an incident plane wave. The theory leads to the Westervelt and Maidanik formulae for force and torque respectively. Alternative forms for the Maidanik formula are generated by application of the generalized optical theorem.
Physical Theory of Fluid Interfaces Near the Critical Point
Authors: Sarkies KW , Richmond P , Ninham BW
Published: June 2013

A continuum theory of surfaces is developed for fluids near their critical points. The free energy of the fluid interface is considered to consist of two terms: the self free energy of inhomogeneity and an energy of interaction across the interface due to van der Waals forces. This second term is computed via the principles of Lifshitz theory and gives a physical basis to Widom's modification of the Cahn?Hilliard theory of surfaces. The scaling laws as derived by Widom are recalculated, and several differences from the original laws emerge. The theory permits calculation of absolute values of surface tensions and interface widths near the critical point from experimental dielectric and free energy data. Furthermore, the fluids considered are not necessarily simple fluids where only pairwise forces are important.
Dependence of Helicon Wave Radial Structure on Electron Inertia
Authors: Boswell RW
Published: June 2013

An analytic expression for the dispersion of travelling helicon waves in a uniform non-resistive plasma is used to show the effect of electron inertia on the radial structure of the wave in a cylindrical plasma bounded by perfectly conducting walls.
The Present Status of the Townsend - Huxley Experiment in Theory and Practice
Authors: Crompton RW
Published: June 2013

Many theoretical investigations have been made of the Townsend–Huxley lateral diffusion experiment but only the most recent have included the spatial variation of the energy distribution function and anisotropic diffusion. Nevertheless, almost without exception, self-consistent and apparently accurate experimental results have been obtained using formulae resulting from these earlier analyses even though, as is now known, these analyses were based on inadequate theoretical foundations. This paradoxical situation has been further confused by the fact that some of the analyses have been based on apparently unrealistic boundary conditions while others have contained an error or a fallacy. A review of the development of the theory up to the present time is given here with the aim of clarifying the position and demonstrating the validity of the data published from a number of laboratories.
Hydrogen Recombination Line and Continuum Observations at 5000 MHz of 13 Southern HII Regions
Authors: Caswell JL
Published: June 2013

Hydrogen 109a recombination line observations are presented for 13 southern HII regions. For four of these and for one additional HI! region new continuum observations at 5000 MHz are also given. Four of the HII regions had previously been incorrectly categorized as supernova remnants. For a number of the other HII regions comparisons are made between the HII velocities and those of associated OH detected in either emission or absorption.
Positions and some Identifications for 111 Sources of about 1 Flux Unit at 408 MHz
Authors: Hoskins DG , Murdoch HS , Hazard C , Jauncey DL
Published: June 2013

Radio positions with an accuracy of ~ 5 sec arc have been measured for a sample of 111 sources that have flux densities in the range 0�6 to 5�5 f.u. at 408 MHz but which are not listed in the 4C catalogue. An investigation of the random background rates for both galaxies and BSO's shows that the expected chance identification rate is small for galaxies brighter than 19m and for BSO's to the plate limit. A comparison of optical and radio positions shows that radio?optical separations of up to 15 sec arc are common for galaxies of 18m or brighter, but rare for BSO's. The identification content, corrected for chance associations, is 16% BSO's and 20% galaxies.
The Radio Continuum of the Large Magellanic Cloud. IV. Spectra of Sources
Authors: McGee RX , M Newton Lynette
Published: June 2013

The continuum radio sources in the direction of the Large Magellanic Cloud are classified in terms of their spectral indices. Of 52 sources for which spectral data were available three distinct classes exist: (1) sources with spectral indices = ?0�20, of which 21 out of 23 have been identified with HII regions in the Henize catalogue; (2) sources with spectral indices < ?0�20 that have been identified with Henize objects, of which it is possible that many are supernova remnants; and (3) sources with spectral indices < ?0�20 that have not been identified with optical objects and are considered to be outside the LMC. Six "double sources" with one member belonging to class (1) and the other to class (2) were found. The background continuum radiation is also discussed.
A Note on the Longitudinal Diffusion of Electrons in Argon
Authors: Robertson AG , Rees JA
Published: June 2013

It has been shown both experimentally and theoretically that the diffusion of electrons subject to the influence of an applied electric field is often significantly different in directions parallel and normal to the electric field (Wagner, Davis, and Hurst 1967; Parker and Lowke 1969; Lowke and Parker 1969; Skullerud 1969). Lowke and Parker (1969) showed that the ratio of the diffusion coefficients (DL parallel to the electric field and DT normal to the field) is particularly sensitive to rapid variations with energy of the momentum transfer cross section of the electrons. It is to be expected therefore that for electrons in argon the Ramsauer?Townsend minimum in the momentum transfer cross section at energies of ~ 0�3 eV will have a marked influence on the value of DL.
Australian Journal of Physics Astrophysical Supplement
Authors: Wall JV
Published: June 2013

A series of observations to determine the spectra of sources in the �4� declination zone of the Parkes 2700 MHz survey is described. The observations have yielded flux densities for 370 sources at 5009 MHz, 300 sources at 1403 and 468 MHz, and 450 sources at 635 MHz, while additional flux densities for many of the sources have been obtained from published measurements from other observatories. Spectral data have also been tabulated for some of the sources found in the Parkes 2700 MHz deep surveys of selected regions. The spectra of a number of the sources are illustrated and discussed. Several of the sources appear to be variable at high frequencies.
Optical Potentials and Eikonal Approximations
Authors: Williamson Jr W
Published: June 2013

An intermediate and high energy scattering approximation is developed by approximating the sum of intermediate states of the target system and expanding the free particle propagator. The resulting expression plays the role of an optical potential and reduces to the eikonal approximation if the average of the excitation energy for the intermediate states is negligible in comparison with the energy of the incident particle.
The 5·80 MeV State of 32S
Authors: Gardner PR , Moss CE , Spear RH , Carlson LE
Published: June 2013

Studies of the reaction 29Si(a, n?)32S indicate that the 5 �80 MeV state of 32S has an excitation energy of 5798� 2�1� 0 keV, a mean lifetime of 14�7 fs, and a spin of 1. Particle?gamma coincidence studies of the reaction 32S(p,p'?)32S indicate that the state decays 100% to the 0+ ground state, with all other possible transitions having intensities ? 2% of the ground state transition. The properties of the state are shown to be consistent with those expected for the 1? member of the negative parity quintuplet predicted by the coupled quadrupole?octupole vibrator model.
Spin Determination from Compound Nuclear Reaction Yields
Authors: Carlson LE , Davidson WF , Zuk WM , Najam MR
Published: June 2013

The relative population of the 2+ levels at 243 and 288 keV and the 3+ levels at 390 and 426 keV in 62Cu via the 62Ni(p, n)62Cu reaction has been compared with the theoretical prediction of the Hauser?Feshbach statistical compound nuclear reaction model. Whereas the yields of the 243, 288, and 426 keV levels are in accord with the Hauser?Feshbach calculations, the observed yield of the 390 keV 3+ level is anomalously low by a factor of six to seven.
Second-order Solutions for Steady Magnetohydrodynamic Channel Flow with Anisotropic Conductivity
Authors: Panton DM
Published: June 2013

Further investigation of steady magnetohydrodynamic flow through a straight channel of arbitrary cross section with nonconducting walls is considered, in the presence of anisotropic conductivity due to the Hall effect, where no restriction is made on the Reynolds number or magnetic Reynolds number. An approximate solution is provided by a perturbation expansion in terms of the Hall parameter, assumed small. Corrections are made to the first-order solutions established by Panton and Hosking (1971) and the solutions are then extended to the second order for a square channel. It is found that both the Reynolds number and magnetic Reynolds number terms have a significant influence on the mass transport, the former far outweighing the contribution to the flow established by Tani (1962) for the values of the flow parameters assumed.
AB Initio Calculations for Helium-4 of Thermodynamic and Transport Properties of the Gas and the Ground State Energy of the Liquid
Authors: Snook IK , Watts RO
Published: June 2013

A potential energy curve for the 4He diatom obtained from a perturbation theory solution of the Schr�dinger equation is used to calculate the viscosity, thermal conductivity, self-diffusion coefficient, and second virial coefficient of gaseous 4He. In addition, the ground state energy of the zero-temperature liquid is obtained by a variation procedure using a trial wavefunction in conjunction with the Monte Carlo method. The results are in good agreement with experiment.
Linear Polarization and Spectrum of PSR 0833?45 and the Effects of Scattering
Authors: Komesaroff MM , Hamilton PA , Ables JG
Published: June 2013

Linear polarization characteristics as well as pulse shape have been measured at Parkes for the average of many pulses from PSR 0833?45 at several frequencies between 300 and 1410 MHz. These confirm a previous conclusion, which was based on pulse shape measurements alone, that the change of pulse character with decreasing frequency can be explained in terms of interstellar scattering. The inferred effect of the scattering medium is explained on the assumption that it comprises many layers of weak uncorrelated density inhomogeneities. Also, some evidence is found for a weak "precursor" pulse, and the possible implications are discussed.
On the Statistical Theory of Nuclear Reactions
Authors: Bertram WK
Published: June 2013

The statistical theory of energy-averaged reaction cross sections is examined using the pole expansion of the S-matrix. Exact expressions for the average cross sections in terms of the parameters of the S-matrix are derived for the case when there are two open channels. It is shown that when the number of channels exceeds two, the average cross sections can be evaluated provided the poles of the S-matrix are evenly spaced.
Rapidity Space Distribution of Multiparticle Production by Proton?Nucleon Collisions at 70 GeV/c
Authors: Daftari IK , Bhattacharyjee DK , Naha SC , Roy J , Ghosh DC , Roy Chowdhury A , Roy T
Published: June 2013

Statistical analyses of the rapidity space distribution for 70 GeV/c p-p collisions in photoemulsion plates lend support to the view that multiparticle production due to hadron-hadron interactions proceeds via an intermediate cluster state.
Quantum Mechanics in Finite Dimensions
Authors: Santhanam TS , Sinha KB
Published: June 2013

This paper contributes to a recent series discussing quantum mechanics defined on a finite-dimensional Hilbert space in which Weyl's commutation relation for unitary operators holds. In an earlier paper, Santhanam and Tekumalla (1976) showed that the commutation relation for hermitian operators with a bounded spectrum tends to Hdsenberg's standard canonical commutation relation as the spectrum becomes continuous and the dimension n -> 00. The present paper offers a formulation which is coordinate free in the limit n -> 00 and makes the limiting procedure especially ransparent.
p-p??n Scattering at Fermilab Energies
Authors: Saleem M , Iftikhar Ahmad M , Rafique M
Published: June 2013

By a phenomenological choice of the residue function, a very good fit with experiment is obtained on a simple Regge pole model using a linear A2 trajectory and energy-independent parameters.
A Parafermion Generalization of Poincaré Supersymmetry
Authors: Jarvis PD
Published: June 2013

The space-time Poincare algebra is extended by introducing a four-spinor generator whose components satisfy certain trilinear parafermi commutation relations. The spin content of the irreducible multiplets is analysed in the massive and massless cases, and weight diagrams constructed, for arbitrary order p of the parastatistics. The supersymmetry algebra of Wess and Zumino, and of Salam and Strathdee, is exhibited as the special case of order p = 1 in this formulation.
Flux Conservation, Magnetohydrodynamic and Force-free Approximations for Relativistically Streaming Plasmas
Authors: Burman RR
Published: June 2013

The purpose of this paper is to clarify the flux conservation, magnetohydrodynamic and force-free approximations, for plasmas whose component species may be relativistically streaming, by paying particular attention to the conditions for their validity and to their interrelationships. All three approximations involve consideration of inertial effects, either in the generalized Ohm law or in the equation of motion of the plasma as a whole. All three imply that the electric field component parallel to the magnetic field is small. The significance of the approximations for pulsar magnetospheric theory is commented on.
A Study of Solar Flare Continuum Events Observed at Metre Wavelengths
Authors: Robinson RD
Published: June 2013

This paper presents observations and an interpretation of solar flare continuum radiaHon. Two types are distinguished: FCM which often precedes a moving type IV burst, and FCII which often follows a type II burst. Theoretical models are proposed for the two types of flare continuum event. For FCM events, the electrons are assumed to be injected into coronal arches, where they are confined by Coulomb scattering and wave-particle interactions. The radiation is due to either gyrosynchrotron or Langmuir wave processes. For FCII events, the electrons are assumed to be accelerated by large amplitude Alfvenic turbulence, the resultant radiation being caused by the conversion of Langmuir waves to electromagnetic radiation at the fundamental.
Absorption of Curvature Radiation
Authors: Zheleznyakov VV , Shaposhnikov VE
Published: June 2013

The reabsorption of curvature radiation, i.e. radiation from relativistic electrons moving along curved magnetic field lines, is discussed. The optical depth for the ray path is calculated by use of the Einstein coefficients. It is shown that the optical depth becomes negative (maser effect) if transitions between Landau levels are absent. However, maser action is ineffective if the energy density of the relativistic particles is less than that of the magnetic field. For pulsar radio emission the magnetic energy density is assumed to exceed the particle energy density, so the observed emission cannot be coherent curvature radiation.
Gamma-ray Studies using a Solid Argon Target: Properties of States in 40K and 40Ar
Authors: Beale DJ , Poletti AR , Southon JR
Published: June 2013

The Doppler shift attenuation method was used to deduce lifetimes of levels in 40 Ar and 4�K populated by the reactions 40 Ar(p, n)4�K and 40 Ar(p, p')40 Ar. Spins and mixing ratios in 4�K were also deduced from angular distribution measurements. The target used was solid argon at a temperature of 66 K. Substantial agreement with other recent work has been found. The results are interpreted using a weak coupling calculation and a simple t5 function interaction model.
Photon Fission in Intense Laser Fields and in the Coulomb Field of a Nucleus
Authors: Lindsey JF , Perlman HS , Troup GJ
Published: June 2013

A calculation of the photon fission cross section in the Coulomb field of a nucleus reveals that the real part of the transition amplitude is the predominant contributor for photon energies up to 2 MeV. Since it is just this part that is associated with the fourth-order vacuum polarization process, it is suggested, given the present developmental state of laser technology, that coincidence experiments with photon fission might well afford a test of higher order quantum electrodynamics.
4? Particle?Hole States in 16O
Authors: Henderson RS , Spicer BM , Svalbe ID , Officer VC , Shute GG , Devins DW , Friesel DL , Jones WP , Attard AC
Published: June 2013

4 - states of 160 at excitation energies of 17�79 and 19�80 MeV (T = 0) and 18�98 MeV (T = 1) are observed to be strongly excited in inelastic scattering of 135 MeV protons at momentum transfers of 200-500 MeV/c. The previous ambiguity in the spin and parity assignments for the 17�79 MeV state is removed.
Low Temperature Transport Properties of the Group V Semimetals
Authors: Issi J-P
Published: June 2013

The group V semimetals are first introduced by comparing their particular band structure with the more familiar typical metals or semiconductors. Recent results on the electrical resistivity, thermal conductivity and thermopower of bismuth, antimony and arsenic are reviewed, with particular emphasis on measurements performed at low and ultralow temperatures. The data are analysed in terms of the peculiar features of the electron and phonon scattering, and reference is made to the band structure and rhombohedral symmetry. Recent improvements in the interpretation of the results are discussed.
Application of the Frahn Scaling Formula to the Analysis of the Excitation of 1- States in 40Ca by 9Be Scattering
Authors: S Eck John , Ophel TR , Weisser DC , Clark PD
Published: June 2013

The simple scaling formula derived by Frahn for the heavy-ion inelastic cross section of excitation of 1 - states in even--even nuclei has been applied to the excitation of the 1 - states in 40Ca at 5�91 and 6� 94 MeV by 45 and 60 MeV 9Be projectiles.
The Non-statistical Population of the 11·10 MeV (4+) State in 160 by 12C(6Li,d)
Authors: Kemper KW , Ophel TR
Published: June 2013

When compound nucleus calculations are normalized to the 13�88 MeV (4+) 12C(6Li, d) 160 cross section it is found that the population of the 11�10 MeV (4 +) state is underpredicted by a factor of 4. This result means that the anomalous population of the 11�10 MeV (4+) state in 160 by the 12C(6Li, d) reaction is not compound nuclear in origin.
Dipole Pomeron and Proton-Proton Elastic Scattering at High Energies
Authors: Saleem Mohammad , Aleem Fazal-e , Kamran Mujahid
Published: June 2013

The differential and total cross sections for high energy pp elastic scattering in the energy range 30�8:;;; st :;;; 62 GeV, with -t extending up to 8 (GeV/c)2, have been fitted with a dipole pomeron model.
Velocity Measurement with Speckle and Speckle-like Photography
Authors: Baker PL , Ninio F , Troup GJ , Bryant R
Published: June 2013

The criteria for image structure and film properties for velocity measurement by speckle-pattern photography are discussed. Even with low intensity light sources, holographic film is unnecessary, and Plus-X-Pan film will record sufficient detail (in multiple exposures if necessary) to form diffraction pattern fringes. Speckle photography techniques can also be applied to appropriately prepared, incoherently illuminated surfaces, so long as the camera image has the correct speckle-like granular structure. Experiments verifying these ideas are described.
The Distribution of Time Intervals Between Cosmic Ray Showers ? A Study of the Randomness of Cosmic Ray Arrival Times
Authors: Clay RW , Gerhardy PR
Published: June 2013

It has recently been reported that cosmic ray showers arrive in an appreciably nonrandom manner with an excessive number of short time intervals between showers. We have investigated the distribution of time intervals between showers of size Ne ;;:; 105 and find that if there is any excess of short intervals it must be ;S 5 %.
Flow Dynamics in Pulsar Magnetosphere Models with Particle Inertia
Authors: Burman RR
Published: June 2013

Steadily rotating neutron star magnetospheres, with the Lorentz force balanced by inertia, are studied. It is assumed that charged particles leave the star with nonrelativistic speeds and that any returning are decelerated so as to be nonrelativistic on impact. No assumptions are made as to where in the magnetosphere substantial acceleration occurs or as to the degree of charge separation. It is found that the main qualitative features of the flow dynamics for the general oblique rotator can be understood by regarding the poloidal speed Vp as a parameter for the azimuthal speed v and Lorentz factor y of a species, and then considering flow curves that represent the variation of v;/c2 along each poloidal streamline. There are two possible flow branches--solutions for v and y-for each curve. One is applicable where the dimensionless non-corotational electric potential 1 -1/x2 there, but is never valid where 1. The flow branches can meet, with infinite gradients of v and y, corresponding to failure of the dissipation-free flow.
The Diffusion Coefficient for Thermal Electrons in Mercury Vapour at 470 K
Authors: Hegerberg R , Crompton RW
Published: June 2013

The diffusion coefficient for thermal electrons in mercury vapour has been measured using the CavaIIeri electron density sampling technique. The result indicates that the average momentum transfer cross section for electrons is ~27 x 10−16 cm2, a result which favours previously derived cross sections from drift velocity data over recent theoretical calculations.
Simple Theory of the ?Negative Residual Linewidth? in Reflection Spectroscopy of Magnetically Concentrated Local Moment Systems
Authors: Stewart AM
Published: June 2013

A mathematically improved analytical approximation is obtained to the solutions of the phenomenological equations of H. Hasegawa that describe the electron spin resonance of local moments in metals and the bottleneck effect that frequently occurs. The approximation shows that at all temperatures above the Curie point () the Iinewidth is proportional to T -- () for any degree of bottlenecking, and not to temperature T. The solution also reveals that the g shift remains explicitly independent of temperature down to the Curie point. The expressions obtained take into account explicitly the direct local moment spin lattice relaxation rate and show that it is effective in breaking the bottleneck.
Nonlinear Double-diffusive Convection in a Moderate Prandtl Number Fluid
Authors: Riahi N
Published: June 2013

Recent work on nonlinear double-diffusive convection in a low Prandtl number fluid is extended to the case of a moderate Prandtl number G'. The boundary layer method is used by assuming a large Rayleigh number R for different ranges of the diffusivity ratio -c and the solute Rayleigh number R; It is found that the heat and solute fluxes F and F; increase with G', Rand n;', and that F; F- 1 is independent of G'. The flow is shown to have a solute layer of thickness proportional to F-1-2, The horizontal wavenumber which maximizes F is found to be independent of G', but it increases with Rand R;1
Mathematical Modelling of the Modulation Transfer Function of X-ray Film/Screen Systems
Authors: K Benke Kurt
Published: June 2013

An exponential equation can be used to characterize the line spread function (LSF) of the X-ray film/screen combination. The analytic Fourier transform of the LSF yields the modulation transfer function (MTF). Predictions using the theoretical model show good agreement with results btained by numerical Fourier transformation. A single figure of merit parameter may be assigned to the film/screen system. This parameter determines the system spatial frequency response.
The Regge Pole Model and Forward Elastic Data at High Energies ? An Analysis
Authors: Kamran Mujahid
Published: June 2013

Using O"to" Re/lm and relevant forward differential cross-section data up to the highest available energies we determine the P, f, p, OJ, A2 intercepts and forward residues in nN, NN and KN scattering. We find evidence for low-lying contributions in the nN and NN non-flip amplitudes including the 0" trajectory in the nN case. We also test various phenomenological notions like exchange degeneracy (EXD) , p universality, OJ universality etc. against our parameter values. Comparison is made with other works.
Neutron Diffraction Determination of Mean-square Atomic Displacements in InAs and GaSb
Authors: Tibballs JE , Feteris SM , Barnea Z
Published: June 2013

Integrated intensities for Bragg reflection of neutrons from single crystals of the III-V compounds InAs and GaSb have been measured at room temperature. The data were collected at two wavelengths, 0'947 and 1�241 A, in order' to establish the adequacy of a correction for moderate to severe anisotropic extinction. Data were also obtained for InAs at four temperatures from 408 to 933 K. Corrections for thermal diffuse scattering were applied. The results were analysed in the one-particle potential perturbation approximation with terms to fourth order in the atomic displacements u == (ut, U2, U3)' At 296 K, the mean-square components <u;) determined were: In, 0'0116(2) A2; As, 0'0102(1) A2; and Ga, 0,0120(3) A2; Sb, 0,0107(3) A2. The third-order coefficients for InAs are comparable with those for Si and Ge, while those for GaSb are comparable with those for zinc cha1cogenides. Below 400 K, the mean-square displacements in InAs decrease faster than predicted by the present perturbation approach.
Doppler Shift of Radio Signals Transmitted between Orbiting Satellites
Authors: Dyson PL , Bennett JA
Published: June 2013

A general expression, applicable at VHF and above, is derived for the Doppler shift of radio signals transmitted between two satellites embedded in the ionosphere. The Doppler shift is made up of several contributions which depend on (a) the rate of change of the free space path between the satellites, (b) the components, perpendicular to the line of sight between the satellites, of both the mean velocity of the satellites and the electron concentration gradients, (c) the moment of the perpendicular electron concentration gradients and the deviations from the mean of the individual satellite perpendicular velocities, (d) the velocity components along the line of sight between the satellites, and the electron concentration values at each satellite, and (e) changes occurring in the ionosphere with time.
Corrigendum: Excitation of the 9·50 MeV (9/2+) State of 13C in Intermediate Energy Scattering Experiments
Authors: Rikus L , Collins SF , Amos KA , Spicer BM , Shute GG , Morrison I , Officer VC , Smith R , Devins DW , Friesel DL , Jones WP
Published: June 2013

(l) In the last three lines of p. 9, and in Fig. 2 (p. 16), the reference should be to a high total angular momentum (I = 4) transition and a lower (I = 2) total angular momentum transition, rather than to L, which implies orbital angular momentum only.
Parametric Instabilities in a Magnetized Plasma
Authors: K Shivamoggi Bhimsen
Published: June 2013

This paper makes a study of stimulated Raman scattering and stimulated Brillouin scattering of an incident electromagnetic pump wave in a magnetized plasma. The background magnetic field is taken to be parallel to the pump electric field. The growth rates of the two stimulated-scattering instabilities are found to be reduced in the presence of the background magnetic field.
Statistical Thermodynamics of Nonideal Plasma
Authors: Wilhelm HE , Khalfaoui AH
Published: June 2013

Based on the Debye model, the free energy of a nonideal electron-ion plasma is calculated for interaction parameters 0 < Y < Ye below the critical solid state value Ye (y = Ze2n1/ 3/KTis the ratio of mean Coulomb interaction energy to thermal energy), which takes into account the energy eigenvalues of (i) the thermal translational particle motions, (ii) the random collective electron and ion motions, and (iii) the static Coulomb interaction energy of the electrons and ions in their oscillatory equilibrium positions. From this physical model, the interaction part of the free energy is derived, which consists of a quasi-lattice energy, depending on the interaction parameter Y, and the free energies of the quantized electron and ion oscillations (long-range interactions).
Corrigendum: An Investigation of the Accuracy of Numerical Solutions of Boltzmann's Equation for Electron Swarms in Gases with Large Inelastic Cross Sections
Authors: D Reid Ivan
Published: June 2013

An error has been found in the computer codes used in the Monte Carlo simulations. The correction for this error alters some of the values of Dol by up to several per cent. The conclusions presented in the paper are however not affected.
Stepwise Electron?Laser Excitation Studies of Atoms
Authors: McLucas CW , MacGillivray WR , Standage MC
Published: June 2013

A new stepwise excitation technique is presented in which single-mode laser excitation is used to probe isotopic effects in inelastic scattering processes between electrons and mercury atoms.
The Pulsed Electron Beam Time-of-flight Method for Measuring Absolute Total Cross Sections: Atomic Helium
Authors: K Jones Robert , Bonham RA
Published: June 2013

Improvements in a previously reported experimental method have made it possible to obtain absolute total electron-scattering cross sections with a predicted accuracy of better than � 2 % (10') for certain electron kinetic energies. As a first example of the application of the new procedures the cross section for helium is reported from O' 8 to 50� 0 eV. Error estimates for all known sources of uncertainty are discussed in detail. The results confirm the earlier work of Kennerly and Bonham and the agreement is, on the average, better than 1 % with no changes in the cross-section shape.
Electron Coincidence Spectroscopy: An Introduction to Momentum Space Chemistry
Authors: Weigold Erich
Published: June 2013

The application of electron coincidence or (e,2e) spectroscopy to obtaining detailed information on the dynamic structure of atoms and molecules is discussed. The technique obtains separation energy spectra and spherically averaged electron momentum distributions for each molecular orbital in the valence region. A brief discussion of molecular orbital density functions in momentum space is given. The results using Hartree-Fock wavefunctions for atomic orbitals and LCAO-MO wavefunctions for molecular orbitals are compared with (e, 2e) data. The sensitivity of the data to electron correlations in either the initial or final ion many body states is discussed and examples are given.
The 55Mn(p,?)56Fe and 55Mn(p,n)55Fe Cross Sections
Authors: Mitchell LW , Sargood DG
Published: June 2013

The cross section of the reaction 55Mn(p, y)56Pe has been measured in the energy range 0�80-2�04 MeV and of the reaction 55Mn(p, n)55Pe from threshold to 2� 04 MeV. Statistical model calculations reproduce the (p, n) cross section to within a factor of 1� 4, but with the (p, y) reaction they fail by a factor ;;;:2 over a significant part of the energy range. Thermonuclear reaction rates are calculated from the data for temperatures in the range (1-5) x 109 K.
Coronal Hole Dynamics
Authors: Summers D
Published: June 2013

The dynamics of high speed streams of solar plasma emanating from a coronal hole is investigated by use of a two-fluid model with polytropic equations of state. Steady outflow is considered along a flow tube which has a radial orientation with respect to the Sun, and a cross-sectional area proportional to r' where r is the heliocentric radius and s is a divergence parameter (~2). All the flow variables are assumed to be functions of r only. The equations of continuity, momentum and state may be used to obtain a single, nonlinear, ordinary differential equation for the outflow velocity, and the problem reduces to the numerical solution of three pairs of simultaneous algebraic equations. It is found that the velocity profiles are generally highly dependent on the divergence parameter s, as well as the polytropic indices. Numerical results are given for a variety of cases most relevant to the solar corona. As s increases from 2, the value appropriate to purely spherically symmetric expansion, the outflow velocity increases throughout the range from the coronal base out to infinity, over a certain parameter range. Although the terminal outflow speed for s > 2 may be far in excess of the purely spherically symmetric value, we find that high speed streams emanating from coronal holes cannot be accounted for by geometrical effects alone. The results may have important applications in the general theory of stellar winds.
Structural Transformations and Their Precursors
Authors: Finlayson TR
Published: June 2013

For a number of materials which exhibit a change of structure on being cooled below a certain temperature Tm, some physical properties display anomalous behaviour at temperatures above Tm. The particular structural transformations in mind have been broadly classified as 'martensitic' and the anomalous physical properties as 'precursive phenomena'. Some debate exists regarding the role of the precursive phenomenon in the kinetics of the structural transformation. The most direct evidence for 'martensite precursors' is obtained from electron diffraction, although various indirect evidence is contained in X-ray, neutron and y-ray diffraction and various physical properties, for example, elastic constants and thermal expansion. In this paper current understanding of 'martensite precursors' is reviewed and examples of data from the A15 structure compounds V 3Si and Nb3Sn,. In-TI and TiNi alloys are discussed.