bluuebunny/crossref_metadata_2025 huggingface dataset:
Contributions by RG Giovanelli to the Study of Magnetic Field Structures
Authors: Livingston W
Published: June 2013

R. G. Giovanelli was appointed as a Visiting Scientist at Kitt Peak National Observatory for six months in both 1975 and 1979, and then for an entire year in 1981. These times proved fruitful to him as well as to the Observatory. The Vacuum Telescope and its 512-channel magnetograph had been completed and were operational. Complementing this was a new powerful 2D image analysis machine called the Interactive Picture Processing System (IPPS). For the first time, solar surface features could be quantitatively observed, usually to a seeing limited resolution composed of arcsec pixels, and then readily analysed as pictures. As is often the case, those who built the instruments remained preoccupied with their perfection, and it fell to Giovanelli to put these new tools to effective use. He did this in a series of research efforts reviewed in the present paper. Happily, he drew many of us in Tucson into his projects, injecting us with enthusiasm and enlarging our knowledge of solar physics in the process.
The Possibility of a Photospheric Dynamo
Authors: Wilson PR
Published: June 2013

Several recent observations are discussed which suggest that the current model for the emergence and decay of photospheric flux does not provide a complete account of all the processes involved.An elementary two-dimensional dynamo is discussed and it is shown how this may be adapted tophotospheric conditions in order to provide a plausible kinematic account of these observations.
The Sunspot Cycle and Solar Magnetic Fields. I. The Mechanism as Inferred from Observation
Authors: G Giovanelli Ronald
Published: June 2013

Observations of solar magnetic and velocity fields can be used to derive the course of events involved in the solar cycle. These differ in three important respects from those of conventional dynamo theories: (i) Polar field reversal. Following the outbreak of a new cycle, magnetic flux released by sunspots diffuses initially by Leighton's random-walk process, but this is soon dominated by the observed poleward flow of about 20 m s - 1 which carries flux to polar regions in about 12 months. Since follower spots lie about 2� higher in latitude than leaders, follower flux arrives in polar regions some two weeks ahead of leader flux, providing a net inflow of follower polarity there until sunspot maximum, reversing the polar field from the previous sunspot cycle and building it up to a maximum. After sunspot maximum, the flux arriving in polar regions is predominantly of follower polarity until or unless spots occur at latitudes so low that flux can diffuse towards and across the equator, predominantly from the lower latitude leader; the effect is doubled by a complementary migration from the opposite hemisphere. This prevents the change in polar flux over the cycle from dropping to zero, and leaves the polarity there reversed at the end of the cycle. (ii) The sunspot cycle. A slow, deeper counterflow, essential for continuity, carries flux strands down in the polar zones and then equatorwards. The concentration of strands is increased continually by differential rotation, and they are dragged continually into contact. Reconnection occurs rapidly except between tubes that are inclined at very small angles. This results in the formation of ropes of flux strands twisted very gently. At some stage they are large enough to float, forming sunspots. The mean sunspot latitude decreases continuously as the flux is carried equatorwards, dying out as the flux ropes become exhausted. The whole process repeats, once again reversing the polar and spot group magnetic fields. Hale's polarity laws follow immediately, and Sporer's law requires only minor adjustments to the predicted velocity of the deep equatorward counterflow. The estimated velocity of this flow is compatible with the observed sunspot and magnetic cycles of 11 and 22 years. (iii) The torsional oscillation. Shear by differential rotation increases the concentration of flux strands; the reaction to strongly sheared flux strands is a tendency to reduce differential rotation. This results in cyclic variations of differential rotation, the phase with respect to sunspot formation being in good agreement with the torsional oscillation observations of Howard and LaBonte (1981) at all latitudes up to 50-55�.
The LT-4 Tokamak. II. MHD Activity
Authors: Cheetham AD , Hamberger SM , How JA , Kuwahara H , Morton AH , Sharp LE
Published: June 2013

An extensive experimental program has been carried out on the MHD activity occurring in the LT-4 plasma during ohmic heating discharges, under.a wide range of reproducible conditions, for 3�6 > q(a) > 2�5. Perturbations are studied by using large arrays of individually monitored magnetic coils, distributed both poloidally and toroidally, and two toroidally separated soft X-ray poloidal arrays. The results show that the behaviour can be broadly classified into four distinct regimes within each of which the observable MHD phenomena are remarkably reproducible, and whose boundaries can be very well described by the single parameter q(a). Although most of the observations conform with those on other tokamaks, some appear inconsistent with the usual interpretation, for example, the assumption of rigid toroidal rotation. Further, while internal m/ n = 1/1 and m = 0 sawteeth activity at the q = 1 surface are clearly defined, the magnetic signals usually ascribed to a 2/1 mode when q( a) .;; 3 are clearly shown to have a predominant 3/1 structure, while activity at the q = 2 surface appears relatively weak
Dielectric Tensor of Weakly Relativistic Electron Distributions Separable in Momentum and Pitch Angle
Authors: Robinson PA
Published: June 2013

The dielectric tensor of a weakly relativistic, magnetized plasma is derived for distributions separable in momentum and pitch angle by using an expansion in powers of the Larmor radius. The results are initially expressed in terms of an integral over the electron pitch angle distribution which is itself unrestricted apart from a single symmetry condition. These results include relativistic and finite Larmor radius effects contributed by harmonics s with - 2 .;;; s .;;; 2 for all propagation angles and thus provide a useful framework for both numerical and analytical investigation of electron cyclotron phenomena (propagation and absorption of waves, maser action, current drive etc.) in a wide variety of isotropic and anisotropic plasmas. Explicit results are presented for the dielectric properties of isotropic, loss cone, anti-loss cone and hollow beam distributions, and for wave propagation perpendicular to the magnetic field. In these cases the pitch angle integrals are performed in terms of functions related to the standard plasma dispersion function.
Finite Element Calculations for Non-radial Oscillations of Stars
Authors: Fiedler RAS , Andrew AL
Published: June 2013

Application of the finite element method to a variational principle of Chandrasekhar, although not suitable for computing stable g modes of non-radial oscillation of stars, is found to be satisfactory for unstable g modes as well as f and p modes
Flux Densities, Spectra and Variability of Pulsars at Metre Wavelengths
Authors: Slee OB , Alurkar SK , Bobra AD
Published: June 2013

We present the results of two-frequency flux density measurements of 74 pulsars with the Culgoora circular array. We show that the spectral index of a typical pulsar steepens markedly from 80 to 1400 MHz, but we found no significant relationship between the metre-wave spectral index and the published pulsar parameters
The Dependence of Measured Drift Velocity on Shutter Open Time in the Four Gauze Time-of-Flight Method
Authors: Williams OM , Elford MT
Published: June 2013

Measurements of ion transit time by the four gauze time-of-f1ight method have been shown previously to have a small dependence on the shutter open time. This effect has been investigated for the case of Kr + ions in Kr and found to be due to the combined effects of diffusion and the injection of asymmetric ion pulses into the drift space. The cause of the asymmetry and procedures for checking for the presence of an error from this source are discussed. It is estimated that the error incurred can be reduced to within the experimental scatter of the measured mobility; that is, to less than �0�15%.
Alternative Scheme of Spontaneous Chiral Symmetry Breaking
Authors: Christos GA
Published: June 2013

We develop an alternative scheme of spontaneous chiral symmetry breaking which is characterized by four-quark condensates instead of (7jq),*O. In this scheme the Nambu-Goldstone bosons acquire a mass squared - m~uark' in comparison with mquark in the usual scheme. The quark mass ratios and the parameters of the scheme are determined by an application to the pseudoscalar nonet spectrum (including 'lT0_'Yj_'Yj' mixing). The decays Iji -+('lT0 , 'Yj, 'Yj}y and Iji' -+ 1ji('lT0 , 'Yj) are also considered. The results do not promote the alternative scheme.
Finite Larmor Radius Modifications to the Magnetoionic Wave Modes and Their Effects on Electron Cyclotron Maser Emission
Authors: Ball LT , Hewitt RG
Published: June 2013

Auroral kilometric radiation, Jupiter's decametric and Saturn's kilometric radio emissions, solar microwave spike bursts and microwave emissions from some flare stars have all been attributed to the electron cyclotron maser instability. The maser instability is usually assumed to involve the generation of magnetoionic waves. We investigate the modifications to the magneto ionic wave modes due to finite Larmor radius (FLR) corrections arising from a 'warm' background electron plasma with a Maxwellian distribution. We then consider the effects of these modifications on maser emission at frequencies near the fundamental of the electron cyclotron frequency fl e. The FLR effects are found to be small; the maximum temporal growth rate generally differs by ~ 10% from that for emission occurring in the magnetoionic modes. Small shifts occur in the frequencies and propagation angles corresponding to the maximum growth rates.
Full CI Extrapolation: Application to H2O with a Double Zeta Basis Set
Authors: Gray PD , Burton PG
Published: June 2013

A previously reported full CI (configuration interaction) extrapolation procedure based on multireference single and double CI, which gave excellent results for H20 at the equilibrium geometry, is extended to two other geometries for which explicit full CI results are known. The technique is shown to provide good results for cases where the SCF (self-consistent field) configuration is not strongly dominant, although degradation of performance is noticeable in these cases. The technique is also used to predict a full CI result for the 21 Al state of H20 with the double zeta basis.
Investigation of the Interaction of Electrons and Lattice Vibrations Using Glassy Metal Thermopower
Authors: Kaiser AB , Christie AL , Gallagher BL
Published: June 2013

We calculate the electron-phonon enhancement effect in thermopower using several different models for the Eliashberg function a2 F(E) which describes the interaction of electrons and lattice vibrations. The behaviour of a 2 F(E) at low energies determines whether the predicted thermopower enhancement shows a peak at low temperatures, but the enhancement is rather insensitive to the detailed spectral shape of a2 F(E) at higher energies. The calculations are able to give a good account of the thermopowers of several glassy metals measured by Gallagher and Hickey (1985), with slightly better agreement obtained for a smooth rather than a Debye-like a2 F(E).
Polariton Modes in Superlattices of Uniaxial Crystals
Authors: Shi Hang , Tsai Chien-Hua
Published: June 2013

We present results of a study of the polariton modes, retarded or non-retarded, in superlattices consisting of alternating layers of uniaxial crystalline and isotropic materials. Novel features not existing in superlattices consisting solely of isotropic materials are predicted.
A Least Squares Computational Method for the Scattering Amplitude
Authors: Das JN
Published: June 2013

A new least squares computational method for the scattering amplitude is proposed. This may be applied without difficulty to atomic and other scattering computations. The approach is expected to give converged results of high accuracy and also to be free from major numerical instabilities. As an example a numerical computation is carried out following the method and some results are presented in partial support of the claim.
Profile Data Acquisition for the JCPDS?ICDD Database
Authors: Jenkins Ron
Published: June 2013

The principal advantage offered by a fully digitised diffraction pattern is the retention of all features of the experimental pattern, including the line width and shape, the form and distribution of the background, etc. A file containing this type of reference data would in the future allow the use of techniques yet to be developed and of data processing, such as peak location, background subtraction and a2 stripping. The availability of digitised reference patterns would also allow the use of pattern-recognition techniques for qualitative phase analysis, as well as offering interesting possibilities for quantitative work. Until recently most commercially available automated powder diffractometers were limited to 10-20 Mbytes of disc storage and since a single fully digitised pattern requires about 10 kbytes, the provision of a file for thousands of digitised single phase reference patterns has not been possible. The recent advent of compact disc-read only memory (CD-ROM) systems providing in excess of 500 Mbytes now offers a low cost data storage capability. Plans are now in place for a new version of the Powder Diffraction File consisting of fully digitised patterns. Because of the need to maintain the database for years to come, it is most important that the stored data be as accurate and complete as possible.
Validity of the Structure Factor Formalism
Authors: Harada Jimpei
Published: June 2013

Where density ftuctuations in a crystal are very large as a result of proximity to a structural phase transition, contnbutions to the diffraction data associated with critical scattering (CRS) can make it difficult to determine the average structure with any great precision. This matter is discussed on the basis of the structure factor formalism.
The Anharmonic Temperature Factor in Crystallographic Structure Analysis
Authors: Kuhs WF
Published: June 2013

The most widely used formalisms to describe anharmonicity and disorder in crystallographic structure refinements are presented and their properties are reviewed. Their limitations are discussed and their range of applications is indicated. A comparative study on the lattice anharmonicity in Zns using different models is presented. The importance of measuring Bragg intensity data sufficiently far in reciprocal space is stressed. Some indications concerning the interpretation of the results are given and the decorrelation of electronic and atomic deformations is briefly discussed.
Concerning Single Crystal Reflectivity Curves
Authors: McL Mathieson A
Published: June 2013

The extinguished reflectivity curve of a Bragg single crystal reflection represents the basic experimental evidence for the determination of accurate structure factors. In normal measurement procedures of one-dimensional (ID) 'counter' profiles, information on such curves is obscured by the presence of other, more dominant components. It is therefore difficult to separate out these curves so that a realistic correction for extinction can be applied. By considering the 'shape' of a Bragg reflection in the plane of diffraction from the ~w, ~2e viewpoint, procedures have been deduced for practical zero wavelength dispersion measurement of reflectivity curves for virtually any e value and, with these curves, corrections can be applied to produce extinction-free structure factor values. Attention is drawn to the fact that the width of the experimental reflectivity curve (say at half maximum) can provide a valuable criterion to assist in attaining the 'kinematical limit'.
Determination of Structure Factors by the Pendellosung Effect for Imperfect Crystals
Authors: Olekhnovich NM
Published: June 2013

An investigation of thickness dependence of the X-ray integrated intensity of monochromatic linearly polarised X-ray radiation in a symmetrical Laue-case diffraction reveals that the method of determination of structure factors f from thickness oscillations can be extended to real crystals with a static distribution of Coulomb-type defects or dislocations. The f E value (where E is the static Debye-Waller factor) is determined from the oscillation period, while E is determined from the tilt-angle tangent of the oscillation axis of the reduced integrated intensity.
Dependence of Zero-field Ion Mobilities on Well Depth and Minimum Position in the Ion-Neutral Interaction Potential
Authors: W Harland Peter , GAR Maclagan Robert , W Simpson Richard
Published: June 2013

The dependence, at fixed temperature, of the zero-fielci ion mobility on well depth E and minimum position r m in the ion-neutral interaction potential is explored. For large values of r m the mobility is very sensitive to small changes in E, but at small r m the mobility varies only slightly from the Langevin value.
Momentum Transfer Cross Section for Electrons in Krypton Derived from Measurements of the Drift Velocity in H2?Kr Mixtures
Authors: England JP , Elford MT
Published: June 2013

Measurements of electron drift velocities have been made in 0�4673% and 1�686% hydrogenkrypton mixtures at 293 K and values of E/ N from 0�08 to 2�5 Td with an estimated uncertainty of <�0�7%. The data have been used in conjunction with the H2 cross sections of England et aL (1988) to derive the momentum transfer cross section for krypton over the energy range 0�05 to 6�0 eV. The drift velocity data have also been used to test the Kr momentum transfer cross sections of Koizumi et aL (1986) and Hunter (personal communication 1988). The cross section of Koizumi et aL is clearly incompatible with the present measurements while the cross section of Hunter has been used to predict these measurements to within 1% to 3%.
Riemann-Hilbert Problem with Higher Order Poles for Self-Induced Transparency with Degenerate Energy Levels
Authors: Roy Chowdhury A , De Mrityunjoy
Published: June 2013

We have analysed the inverse problem for self-induced transparency with degenerate energy levels (DSIl) via the Riemann-Hilbert methodology with second order poles. The required formulae are deduced in detail and the corresponding soliton solutions are obtained. It is noticed that the profile of the single soliton is not of the usual sech type.
Observation of Spatial Variations in the Energy Distribution Function for Steady-state Townsend Discharges
Authors: Wedding AB , Kelly LJ
Published: June 2013

Spatial variations of the relative excitation rates for two electronic states of molecular nitrogen have been measured for a point source Townsend discharge. The ratio of these rates shows a spatial dependence which is explained in terms of an electron con,centration gradient expansion of the energy distribution function. The electronic states were chosen to have quite different thre hold energies such that the ratio would be sensitive to small changes in the electron energy distribution. A model for secondary electron production is used to explain the significant influence of secondary ectrons in the outer regions of the discharge.
Structural Differences between RbMnCl3 and RbMnBr3
Authors: Ali EM , Felimban AA
Published: June 2013

The crystal structures of RbMnCl3 and RbMnBr3 were determined to be hexagonal P63/mmc. The differences between these two structures are that in RbMnCiJ there are six close-packed layers while there are two close-packed layers in RbMnBr3. Moreover, in the latter structure the Mn-Br octahedra share opposite faces to form infinite chains of composition (MnBr3) parallel to the c-axis, while in the RbMnCl3 structure such an infinite chain does not exist
H2O Masers in the Galactic Plane. II. Longitudes 260° to 326°
Authors: Caswell JL , Batchelor RA , Forster JR , Wellington KJ
Published: June 2013

We present details of 53 H20 masers located in the galactic plane between longitudes 260� and 326�. Twenty-one of these are new ones found at the sites of recently discovered OH masers. The properties of the individual masers are discussed, in particular the variability of sources known for several years and the high velocity emission exhibited by some masers. The association of H20 and OH masers has been investigated and out of 36 OH masers in this region of sky, a remarkably high number (34) have nearby H20 masers.
High Pressure Studies of the Superconducting Transition in (Bi, Pb)2Sr2Ca2Cu3O10
Authors: Lusk J , Freeman TE , Erdman DA , Driver R , Macfarlane JC
Published: June 2013

The superconducting transition for a bismuth-lead superconductor has been investigated t helium pressures to 500 MPa. The form of the resistance transition is similar at all ressures and shows a marked discontinuity at -107�5 K for the material nvestigated.
Field Enhanced Intrinsic Fluctuations in Highly Oriented High Tc Thin Films
Authors: Smith CB , BelI JM , Savvides N , Filipczuk S , Andrikidis C
Published: June 2013

Experimental resistance versus temperature plots measured in various magnetic fields up to 7 T in strength are presented for highly oriented YBaCu oxide thin films deposited onto crystalline zirconia. Possible broadening mechanisms are summarised and a detailed analysis made for three models which involve processes intrinsic to the ideal superconducting material. It is shown that two distinct potentials may be needed to understand flux pinning in different temperature ranges below Te. These two potentials have quite different temperature and field dependence.
Effect of Small-scale Inhomogeneities on the Dispersive Properties of a Plasma
Authors: Melrose DB , Percival DJ
Published: June 2013

A theory is developed to describe the effect of small�scale inhomogeneities or 'ripples' in an unmagnetised plasma on the properties of transverse waves with wavelength long compared with the scale length of the ripples. The procedure used is ased on a covariant version of nonlinear plasma kinetic theory. A simpler theory, which is more physically transparent, is explored in an appendix, and is found to reproduce the results of the more rigorous theory only in the simplest limiting cases.
Static and Dynamic Moments of the 7Li Nucleus
Authors: Barker FC , Kondo Y , Spear RH
Published: June 2013

The data of Weller et al. (1985) on the tensor analysing powers for elastic and inelastic Coulomb scattering of aligned 7U ions have been reanalysed in order to obtain information on the values of the four 7U moments Q, B(E2)j, Til and T12. It is shown that a single set of values, chosen primarily to be consistent with the value of Q measured by molecular techniques and the values of B(E2)T and TI2 required to fit unpolarised 7U data, and also with the theoretical constraint Til "" -I Tl2I, gives a good fit to the aligned 7U data.
Spectral Distortions of the Relic Radiation from Pregalactic Dust and Decay of the Unstable Particles
Authors: Nasel'sky PD , Novikov ID
Published: June 2013

Results are presented of calculations of the cosmic background radiation spectral distortions due to the pregalactic dust being heated by the decay of unstable particles.
Flat-spectrum Radio Sources from the Parkes 2· 7 GHz Survey ? A Study of a Complete Sample
Authors: Savage Ann , L Jauncey David , L White Graeme , A Peterson Bruce , Peters WL , Gulkis Samuel , Condon JJ
Published: June 2013

We describe our complete sample, taken from the Parkes 2�7 GHz catalogue, of flat-spectrum radio sources with flux densities > 0�5 Jy. The sample covers all right ascensions and declinations from +10� to -45�, excluding the galactic plane (lhI < 10�) and contains 403 sources. Attention is drawn to the advantages of radio surveys over optical surveys. The survey is used to highlight some selection effects found in optical surveys. We also discuss how this sample can be used to give us information on the early universe
Auger Photoelectron Coincidence Spectroscopy
Authors: Thurgate SM
Published: June 2013

Auger photoelectron coincidence spectroscopy (APECS) involves measuring an Auger line in coincidence with the corresponding photoelectron line of an X ray excited spectrum. Such spectra are free of many of the complicating features of conventional data and display the correlations that exist between the lines. APECS has been used to study a number of fundamental aspects of Auger spectroscopy, such as the removal of complicating effects due to Coster-Kronig transitions in the LZ.3 VV spectra of Cu. We have been able to show similar behaviour in the Auger spectra of Co. In principle, APECS can also be used to make measurements of surface core level shifts, to examine the process of electron scattering in solids, and it holds some promise as a technique for the routine examination of materials. The coincidence technique discriminates against secondary electrons in the background, the Auger and photoelectron peaks appear on a flatter background, and this helps to make the interpretation of Auger data collected in coincidence more straightforward. A number of successful APECS experiments have been constructed, using either X ray tubes or synchrotrons as sources. When an X ray tube is used as a source, the principal problem has been with the length of time needed to acquire a sufficient number of counts. We have recently completed construction of a novel spectrometer that goes someway towards overcoming this problem, however the challenge still remains to produce an instrument that will permit routine measurement of these features.
A Study of L2 Approximations in Atomic Scattering
Authors: Stelbovics AT , Winata T
Published: June 2013

The approximation of Coulomb continuum functions by an L 2 basis is studied using a Laguerre� function basis which can be extended to completeness. Also studied is the convergence rate of L2 approximations to Born matrix elements for electron impact ionisation as a function of basis�set size. This important class of matrix elements occurs in pseudo�state close-coupling calculations, accounting for scattering to the three�body continuum. Convergence rates in both cases are derived analytically and confirmed numerically. We find that the rate of pointwise convergence of L2 expansions to the continuum function is slow, and of conditional type; however, it is proven that the corresponding ionisation matrix elements converge geometrically, Our result agrees with the behaviour observed in pseudo�state calculations.
A LEED Fine Structure Study of Oxygen Adsorption on Cu(001) and Cu(111)
Authors: Hitchen C , Thurgate S , Jennings P
Published: June 2013

LEED fine structure features are due to an interference between the measured beam (usually the specular) and a pre-emergent beam. This pre-emergent beam is internally reflected at the surface potential barrier and is subsequently diffracted by the substrate into the same direction as the beam under observation. As a result of the long-range image nature of the barrier potential, a rydberg-like series of peaks, converging on the emergence energy of the pre-emergent beam, is produced. Fine structure features, or threshold effects, occur at very low incident beam energies (typically <40 eV) and are extremely sensitive to the surface order of the crystal. The changes that occur to the fine structure features when atoms are adsorbed onto the surface contain information regarding the nature of the chemisorption process. In some cases it is possible to infer adsorption sites. In this work measurements are made of the fine structure features for the (001) and (111) surfaces of copper as a function of oxygen exposure. Analysis of these data shows that oxygen adsorption on (u(111) takes place in a disordered manner and results in a roughening of the surface, while for (u(OOl) the adsorption produces an ordered overlayer with oxygen atoms in the 2-fold bridge sites.
Foreword
Authors: Weigold Erich , Cahill Reg
Published: June 2013

In July 1990 a meeting on Quantum Structures was held in Adelaide. The meeting was in honour of Ian Ellery McCarthy on the occasion of his sixtieth birthday. Ian, who is currently Professor of Physics and Associate Director of the Electronic Structure of Materials Centre at Flinders University, has had an enormous influence on the development of physics and physicists within Australia. He has always been interested in and active in promoting good physics and good young physicists. He was also instrumental in establishing the physics department at Flinders University and ensuring that it was very successful in its research activities. Those of us who have known Ian for some time have always admired him for his great enthusiasm for physics, for Australian Rules Football and for life in general.
Soliton Matter
Authors: Dodd LR
Published: June 2013

Although quantum chromodynamics is generally accepted as the fundamental theory of the strong interactions, there exist no solutions to the theory which describe the binding of quarks to form the observed particles of nuclear physics. Soliton bag models of hadronic matter attempt to capture the main features of quark confinement, while remaining amenable to calculation. In the context of the non-topological soliton model, nuclear matter is regarded as a collection of quark clusters arranged on a regular lattice in bag-like soliton structures. The conjectured phase transition of nuclear matter to quark plasma at high densities is then modelled as the melting of the soliton crystal under compression. This paper reviews some recent results on multi-soliton solutions of the linear sigma model in one space and one time dimension. Remarkably, exact periodic soliton solutions can be derived in terms of complete Jacobi elliptic integrals for arbitrarily large lattices. The conditions for a phase transition in the model, and implications for more realistic calculations are discussed.
Composite Mesons in Self-confining Chiral Solitons
Authors: Tandy PC , Frank MR
Published: June 2013

Most quark-meson models for formation of a baryon as a bag or soliton solution begin with elementary local meson fields including a classical scalar configuration that provides repulsion of valence quarks from the vacuum. We explore aspects of the very different formation mechanism that operates in a model where chira\ effective meson fields are composite objects generated from bilocal qq fluctuation fields and the dynamical quark mass can be self-confining. Speculations are made on whether this viewpoint can motivate meson-nucleon relativistic field models containing intrinsic cutoffs for use in nuclear physics.
The Quantum Mechanical Inverse Scattering Problem at Fixed Energy and Some Recent Applications
Authors: Allen LJ
Published: June 2013

Much of the information on electronic, atomic, nuclear and particle physics is obtained in scattering experiments. The inverse scattering problem is to deduce the interaction between the colliding particles, or what their constitution is, from the observed data. Inverse scattering techniques at fixed energy which have lent themselves to practical application are reviewed. Some recent applications, in particular to electron-atom scattering, are discussed. New results for e-He scattering at 30 eV are presented.
The Development of Electron Momentum Spectroscopy
Authors: Weigold Erich
Published: June 2013

The study of the valence electronic structure of atoms and molecules by (e,2e) spectroscopy, or EMS as it is now known, began in the early 1970s with a series of measurements at Flinders University. The first measurements were on argon, and they showed the importance of correlation effects in the inner valence 3s shell. The first molecular experiments were on methane, and they showed the sensitivity of the momentum distributions to details of the orbital wavefunctions. Until recently all EMS measurements were made on ground state targets with random orientations. We have, however, now made successful EMS measurements on excited states and oriented targets. Sodium atoms in the 32S1/2(F=2) ground state are optically pumped by right-handed circularly polarised light to the excited 32P3/2(F'=3, 1'111"=3) state. Thus the excited atoms are all in the I .e=l, me=l} state. These measurements are discussed in some detail.
Experimental Study of Quantum Structures in Solids
Authors: J Nygaard Kaare
Published: June 2013

The object of the experiment is to measure electron binding energy spectra in solids at a series of selected bound electron momenta. The present apparatus is based on developments in atomic and molecular spectroscopy and uses a 10 keY electron beam incident on a thin (80 A) amorphous carbon film. The exit electrons in the (e,2e) reaction are studied in a symmetric coplanar geometry using hemispherical analysers and position-sensitive detectors. The resultant coincidence count rate is proportional to the probability of finding a target electron with a given binding energy and momentum. Data were obtained with binding energies from 0 to 40 eV with momentum as parameter. Contributions from the rr and u bands are clearly demonstrated. Future investigations in a new experimental system will be devoted to single crystals of metals, semiconductors and macro-molecules.
Growth and Properties of Large Single Crystals of YBa2Cu3O7-d from BaCuO2/CuO Flux
Authors: Hunter BA , Town SL , Matthews DN , Russell GJ , Taylor KNR
Published: June 2013

Large single crystals of YBa2Cu307-o have been grown using a BaCu02/CUO flux whose composition lies close to the eutectic in the Y-Ba-Cu-o phase diagram. While the largest crystals produced were '" 20x20xO� 7 mm3, the average size of the remaining crystals was approximately 10x10xO� 5 mm3. These crystals, both as-grown and oxygen annealed, have been characterised using susceptibility measurements, optical and scanning microscopy and X-ray and neutron diffraction techniques.
Quark Mass Thresholds in Quarkonium Systems
Authors: Gorman RM , HJ McKellar Bruce
Published: June 2013

We consider the role of quark mass thresholds in quarkonium systems, which are formed by the binding of heavy quark-antiquark pairs and are manifest in the IfJ and Y families of mesons. Such systems provide a probe of the interactions of quarks in a region accessible to the predictions of perturbative quantum chromodynamics (QCD), as well as in the long range region where the interaction is expected to show confining behaviour consistent with our knowledge of light quark systems. A prescription for deriving an interaction linking these two limits has been developed by Buchmiiller, Grunberg and Tye (1980, 1981) and has been successfully applied to the IfJ and Y systems, leading them to suggest a value for the QCD scale parameter AMS" of 500 MeV. In this work we extend this formalism by incorporating the effects of allowing the virtual quarks which contribute to the interaction to have finite masses. These masses must be considered energy dependent, and it is found that while the properties of IfJ and Y states are insensitive to the detailed way in which the masses vary, the presence of mass thresholds has the effect of weakening the ability of this model to set the value of AMS ' with 500 MeV becoming an approximate lower bound.
Nuclear Equation of State as Determined by the Quantum Virial Expansion
Authors: Sperber Daniel , Srinivas Smita , Zielinska-Pfabé Malgorzata
Published: June 2013

The quantum virial expansion is used to investigate the properties of neutron matter in the temperature range 20 < kT < 60 MeV. The pressure as a function of temperature is determined for various densities of neutron matter. Also the stiffness, the energy and the coefficient of volume expansion all as a function of temperature and density are studied.
Origins of the Molonglo Radio Observatory ? The Cross and the MOST
Authors: Mills BY
Published: June 2013

The history of the Molonglo Radio Observatory is reviewed from initial steps in 1960 through the construction of the Cross and its conversion to the MOST. Some of the problems are discussed and the reasons behind various design decisions are explained. A selection of early scientific programs carried out with the Cross is briefly described.
Compact Structure in Continuum Radio Sources
Authors: Schilizzi RT
Published: June 2013

Present-day VLBI networks make observations of compact structure in a wide variety of radio sources. Examples are shown of milli-arcsecond scale structures in radio galaxies, quasars, stars and supernova remnants.
Ca? and Its Elusive Properties
Authors: R Peterson James
Published: June 2013

The historical progression of theoretical and experimental information on the properties of the two electronic states of the Ca- ion is reviewed. New results are described that have revealed a shape resonance and a Cooper minimum, and have yielded a much lower electron binding energy for the ground state Ca- 2p of only 18�4�2�5 meV compared with the previous value of 43�7 meV, and have also confirmed earlier observations of the metastable 4p state. Some important uncertainties still exist and are noted.
Numerical Modelling of Star Formation in Giant Molecular Clouds
Authors: Lattanzio JC , Monaghan JJ
Published: June 2013

We review some of the difficulties associated with understanding star formation, and discuss some numerical approaches. In particular we describe a method which seems to hold promise for future studies.
The Ratio DT/µ for Electrons in a 0·5% Hydrogen?Krypton Mixture
Authors: Elford MT , Brennan MJ , Ness KF
Published: June 2013

The ratio DT / J1. for electrons in a 0�4673% H2-99 . 5327% Kr mixture at 295 K has been measured by the Townsend-Huxley method in order to obtain data for use in the derivation of the momentum transfer cross section for krypton. The values of E/N and pressures sed ranged from 0�025 to 1� 4 Td and 13�43 to 68 �16 kPa respectively. At a given value of E/N and pressure the derived values of DT / J1. were found to depend on the choice of the mathematical expression which relates the measured current ratio to DT/J1.. However, the values obtained using each of the expressions, when extrapolated to infinite pressure, agreed to within 0�5% for all E/N values ~0�07 Td.
Generation via Limiting Procedures of New Solutions in a Nonsymmetric Gravitational Theory
Authors: Vlachynsky EJ
Published: June 2013

New electromagnetic Bianchi type I solutious with nonzero cosmological constant, which satisfy the field equations of a nonsymmetric gravitational theory, are obtained from static solutions. This is achieved by taking a limit of the nonsymmetric tatic solutions.
Some Remarks on the Use of Effective Charges in the Study of Electron Impact Ionisation Processes
Authors: T Whelan Colm , Walters HRJ , Dreizler RM
Published: June 2013

The first-order effective charge description of the electron impact ionisation of H(ls) is considered. The effect of imposing the Peterkop relation on the charges occurring therein is discussed. A special case corresponding to high energy asymmetric geometry is considered and values for the effective charges deduced by comparison with the most accurate available theoretical and experimental data.
Electron Liquid in Double-layer Structures
Authors: Swierkowski L , Neilson D , Szymanski J
Published: June 2013

Two layers of electrons or holes trapped at the adjacent interfaces of a gallium arsenide heterostructure can interact through the Coulomb interaction; this leads to a rich phase diagram of ground states, some of which are inhomogeneous in density. The cause of this is associated with each layer's acting as a polarisable background for the other, making it much easier for inhomogeneous configurations to be stable. Even in the uniform liquid phase the presence of a second layer can qualitatively change the nature of the low lying excitation spectrum and lead to large many-body effects in the spectrum, even at very long wavelengths.
Introduction
Authors: White Guy
Published: June 2013

This issue of the Australian Journal of Physics and the preceding Festschrift Symposium on 'Electrons in Solids-The 1990s and Beyond', held at Monash University on Friday 11th December 1992, honours the career of Geoffrey Charles Fletcher, a distinguished theoretical physicist who celebrated his 70th birthday earlier in 1992. Geoff Fletcher has contributed to solid state physics in Australia for thirty-five years, the first eight being spent in the Department of Applied Mathematics at Sydney University and the rest at the Physics Department of Monash University. In both centres, Geoff has been a stimulating and willing helper to many of us.
High-temperature Thermodynamics of the Hubbard Model
Authors: Oitmaa J , Henderson JA
Published: June 2013

Recently derived 10th-order high-temperature expansions for the Hubbard model are used to obtain the ferromagnetic susceptibility and specific heat at high temperatures. Numerical results are obtained for the simple cubic and face-centred cubic lattices by using Pade approximants to sum the series. The results are compared with two solvable limiting cases, namely the non-interacting limit U = 0 and the strongly-correlated or atomic limit t = O.
Magnetic Moment Distribution in Ferromagnetic Co?Mn Alloys
Authors: Hicks TJ , Wildes AR
Published: June 2013

Using the magnetic environment model, the moment distributions for ferromagnetic COl_xMnx alloys in the composition range (0 < x < 0�25) were calculated from the mean saturating moments of the alloys. The calculation also gives the mean moment of each species as a function of concentration. The predictions correspond extremely well with the existing experimental data. In particular, the increase in the correlation length close to the ferromagnetic critical concentration is clear in the cross section data and model.
Modulational Interactions of Two Monochromatic Waves and Packets of Random Waves
Authors: Vladimirov SV , Popel SI
Published: June 2013

The modulational instability of Langmuir waves in unmagnetised plasmas is reviewed for the cases when a pump consist of two monochromatic or a large number of random modes. It is demonstrated that the correct theory for the modulational instability operates with 'renormalised' equations for the linear dielectric function as well as for the effective third-order plasma response. This renormalisation is due to so-called interference terms. The appearance of interference terms is a specific feature of the multi-mode modulational instability in comparison with the well-known instability of a single mode. All calculations use a simple and universal formalism including new methods developed for description of the modulational effects in arbitrary media. The modulational instability of two pump Langmuir modes is considered for the case of comparatively small instability rates, when 'renormalised' expressions for linear and nonlinear plasma polarisation responses provide the maximum effect on the instability development. For instabilities of the broad spectra of random waves, the integral equations are presented for perturbations of wave field correlation functions. In the description of the modulational instability of random wave packets these equations play the same role as the set of coupled equations for the fields of modulational perturbations in the case of two monochromatic pumps. Rates and thresholds of the instabilities are found in various limits.
The Physics of Tachyons III. Tachyon Electromagnetism
Authors: L Dawe Ross , C Hines Kenneth
Published: June 2013

A new formulation of the theory of tachyons using the same two postulates as in special relativity is applied to electromagnetism. Tachyonic transformations of the electromagnetic fields E and B are rigorously derived from Maxwell's equations and are shown to be the same as for bradyonic transformations. Tachyonic transformations of current density, charge density, scalar and vector potentials are also derived and discussed. Tachyonic optics and the four-potential of a moving tachyonic charge are also discussed, along with generalised four-vector transformations and electromagnetic four-tensors in extended relativity. Use is made of a switching principle to show how tachyons automatically obey the law of conservation of electric charge in any inertial reference frame, even though the observed tachyon electric charge is not an invariant between observers. The electromagnetic field produced by a charged tachyon takes the form of a Mach cone, inside which the electromagnetic field is real and detectable, while outside the cone the field generated by the tachyon is imaginary and undetectable.
Eulogy to John G Bolton
Authors: Wild JP
Published: June 2013

We are gathered here to pay tribute to a very special man. I think that John Bolton will be remembered first and foremost for his contributions to astronomy and to human knowledge. He was the pioneer of extragalactic radio astronomy and therefore also the person who set off the great revolution in astronomy which has occupied the second half of the 20th century. In that revolution astronomers have studied, and opened up, the far regions of the Universe by discovering galaxies and objects of extremely high energy and luminosity.
Extragalactic Radio Sources and the Role of Relativistic Jets
Authors: V Bicknell Geoffrey
Published: June 2013

This paper summarises some of the ideas surrounding the role of relativistic jets in radio galaxies and quasars and describes work presented in two recent papers (Bicknell 1994a,b) relating relativistic jets to the Fanaroff~Riley classification of radio galaxies. I conclude with some speculation on the evolutionary connection between Fanaroff~Riley Class I and Class II radio galaxies and the relationship between mergers and radio galaxies, an idea which was discussed at the time of the discovery of Cygnus A and Ccntaurus A.
Solitary Magnetosonic Waves in Relativistic Plasma
Authors: Mukherjee Joydeep , Roy Chowdhury A
Published: June 2013

We have analysed the formation of solitary magnetosonic waves propagating in a direction perpendicular to the magnetic filed in a relativistic two component plasma. Our approach is that of the effective potential. Variations of the effective potential and the solitary wave in relation to the Mach number and other parameters are discussed.
Self-focusing of Nonlinear Waves in a Relativistic Plasma with Positive and Negative Ions
Authors: Mukherjee Joydeep , Roy Chowdhury A
Published: June 2013

We have analysed the phenomenon of self-focusing of nonlinear waves in a relativistic plasma consisting of both positive and negative ions, which are assumed to be hot. We also consider the effect of the inertia of the relativistic electron by treating it dynamically. A modified form of reductive perturbation is used to deduce a nonlinear Schr�dinger equation describing the purely spatial variation of the nonlinear wave. Self-focusing of the wave can be ascertained by analysing the transversal stability of the solitary wave. It is shown that the zones of stability of the wave may become wider due to the mutual influence of various factors present in the plasma, thus favouring the process of self-focusing.
Frequency Variation of the Mean Energy of rf Electron Swarms
Authors: Robson RE , Maeda K , Makabe T , White RD
Published: June 2013

Starting from the general momentum and energy balance equations for charged particle swarms in a gas, as furnished by momentum-transfer theory, we obtain expressions for mean velocity and mean energy of an electron swarm in an r.f. electric field under spatially uniform conditions, in the frequency range WTe > 1, where Te is the energy collisional relaxation time. If Te is a decreasing function of energy, it is shown that the cycle-averaged mean energy reaches a maximum at a certain frequency. Physical arguments are provided to support this result and the prediction is verified for a constant elastic cross section model by direct numerical solution of Boltzmann's equation.