bluuebunny/crossref_metadata_2025 huggingface dataset:
21 cm Observations of NGC 45
Authors: Lewis BM
Published: June 2013

Observations of NGC 45 have been made at a wavelength of 21 cm using the radio telescope at Parkes. Line profiles have been measured for a grid of 44 points spaced at intervals of 6' arc. From the measurements the mass of neutral hydrogen is calculated to be 8�2 � 108 M?, assuming a distance of 3 Mpc. A simple self-consistent model is determined by computing line profiles to compare directly with the observations. This enables the rotation curve to be corrected for the first-order effects of beam smoothing and results in a total limiting mass of 2�5 � 1010 M?.
On the Drift Velocity of Electrons in a Gas
Authors: Paveri-Fontana SL
Published: June 2013

In a recent paper, Crompton, Elford, and Robertson (1970; hereafter referred to as CER) considered certain questions concerning the steady-state distribution of electrons moving in a neutral gas under the influence of a uniform electric field E. The present communication comments on some aspects of the error discussion in the Appendix of the paper by CER. The analysis will be restricted to the case of isotropic scattering.
Indexing Powder Patterns for High Pressure Sulphur, Phases I and III
Authors: Roof RB
Published: June 2013

Three high pressure phases of sulphur have been reported by Geller (1966). The material designated fibrous sulphur (phase II) was indexed by Geller on the basis of single crystal type photographs, first (Geller 1966) as C-centered ortho-rhombic and later (Geller and Lind 1969) as monoclinic. The structure of this material has also been determined (Lind and Geller 1969). However, no unit cells or structures have been proposed for phases I and III.
Corrigenda
Authors: Munro REB
Published: June 2013

Observations at 408 MHz of radio sources from the 4C catalogue. By R. E. B. Munro "I. Declination range ?7� to ?3�." pp.263-91 "II. Declination range ?3� to 0�." pp. 617?30 Owing to an error in the computer program used to produce Table 4 of Part I and Table 1 of Part II, the quoted declination errors are generally too small. A first-order correction may be effected by multiplying the quoted errors by (secz)/(secd), where z is the zenith angle and d the declination. This correction factor leads to a slight overestimation (= 12%) for the stronger sources.
Australian Journal of Physics Astrophysical Supplements Number 22, May 1972
Authors: Munro REB
Published: June 2013

Observations at 408 MHz of radio sources from the 4C catalogue. IV. Declination range 20� to 0�. By R. E. B. Munro Abstract. Radio positions and flux densities measured at 408 MHz with the Molonglo radio telescope are given for 1392 sources from the Fourth Cambridge catalogue in the declination range 20� to 0�. The mean spectral indices between 178 and 408 MHz are also considered in the light of these improved flux densities.
The Boundary Condition Parameter in R-Matrix Theory
Authors: Barker FO
Published: June 2013

In the general R-matrix theory of nuclear reactions, all measurable quantities such as the cross sections scc' should be independent of the choice of the boundary condition parameters Bc although the values of the level parameters E? and ??c depend on the Bc. For applications involving only a finite number of levels ?, it is not obvious that this is still the case as completeness arguments can no longer be used. It is shown here that scc' can be made independent of the choice Bc of for any finite number of levels and any number of channels, and the resulting formulae giving the dependence of E? and ??c on Bc are derived. An application is made to the pair of 5/2- levels of 7Li near 7 MeV excitation.
Transformation of Bremsstrahlung Photoneutron Data to Data Corresponding to Monochromatic Gamma Excitation
Authors: Thies HH , Barrett RF , Lee F , Kooh R , Crawford DM , Thomas BW
Published: June 2013

Using the count-ratio technique described by Thies and B�ttcher one can coarsely measure with a multi-BF3-counter neutron detection system the 4p-integrated neutron spectrum, neutron mean energies, and related functions in photoneutron experiments using bremsstrahlung, It is shown here how the bremsstrahlung photoneutron data can be used to calculate the equivalent data that correspond to an idealized experiment using monochromatic ?-rays. Simple formulae are derived which permit an estimate to be made of the accuracy of the transformed neutron data.
Observations of the Backscatter of Ultrasonic Waves from a Rough Water Surface
Authors: Dexter PE
Published: June 2013

An experiment is described in which measurements are made of the Doppler frequency shift imposed on an acoustic signal by resonant backscatter from a wind-generated rough water surface. In particular, for the case where the water waves have plane wave fronts and move in a single direction across the surface, the effects on the Doppler shift of varying the horizontal angle of incidence of the acoustic beam with respect to this direction of movement are studied. Some simple theoretical concepts are invoked in an attempt to explain the apparent dependence of the Doppler frequency shift on the azimuth angle measured from the acoustic beam radial direction. Because of the analogy which exists between the scattering of acoustic and electromagnetic waves from the sea surface, it is proposed that a model employing a procedure similar to that described here would be of use in interpreting data gained in large-scale ocean backscatter experiments.
The Absorption by the Interstellar Medium of 80 MHz Radio Emission from Galactic Supernova Remnants
Authors: Dulk GA , Slee OB
Published: June 2013

High resolution 80 MHz observations of 20 galactic supernova remnants have been made with the Culgoora radioheliograph. More than half of the sources have an unexpectedly low flux density at 80 MHz, probably as a result of free?free absorption taking place in the inner arms of the Galaxy. The observations imply an r.m.s. electron density of about 0�1?0�5 cm?3 along the line of sight. This large value for the electron density seems to require a greater ionizing flux than that which occurs in the solar vicinity.
Australian East?West Baseline Interferometer Observations at 2·3 GHz
Authors: Gubbay JS , Legg AJ , Robertson DS
Published: June 2013

In 1967 the two Australian stations of the NASA?JPL Deep Space Network, DSS41 at Island Lagoon near Woomera and DSS42 at Tidbinbilla near Canberra, were operated as an intensity interferometer (Gubbay and Robertson 1967). At the operating frequency of 2�3 GHz, the baseline is 9 � 106 wavelengths in extent and runs 15� south of east from DSS41. In the work reported by Gubbay and Robertson, the flux from the radio source 3C 273 was found to be partially correlated. This note concerns later measurement over the same baseline using an intermediate interferometer (Clark 1968).
Detailed Calculations of Correlations Occurring in Light-Particle-Accompanied Spontaneous Fission
Authors: de L Musgrove AR
Published: June 2013

Detailed trajectory calculations are made for (a-particle-, triton-, and proton- accompanied fission of 252Cf. Comparison between experimental values of the quantity and those deduced from the classical three point charge model suggests either that the initial Coulomb potential energy at scission has a narrow distribution (a result found by Feather 1971) or that a high degree of anticorrelation occurs between the initial potential energy and the initial kinetic energy of the fissioning system. In the latter case, the initial potential energy may be much broader.
Mathematical Model for a Group of Electrons Drifting Between Plane Parallel Electrodes
Authors: Huxley LGH
Published: June 2013

A mathematical model for a group of electrons drifting in a gas in a uniform electric field is proposed. The relevance of this model for the assessment of the errors that arise from forward and backward diffusion to anode and cathode in time of flight measurements of drift velocity is discussed. The theory of steady streams from pole and dipole sources is related to that of the travelling group.
Calculated Self-Diffusion Coefficients for Liquid Argon
Authors: Fisher RA , Watts RO
Published: June 2013

The method of molecular dynamics has been applied with the Barker?Bobetic pair potential for argon interactions to calculate the self-diffusion coefficients of liquid and dense gaseous argon. These self-diffusion coefficients are compared with experimental values and with values obtained from the Lennard?Jones potential. There are significant differences between the calculated and experimental values at high densities.
Classification of Supernova Remnants and HII Regions from their Recombination Line Emission
Authors: Dickel JR , Milne DK
Published: June 2013

H109a, recombination line observations are used in an attempt to classify 46 galactic radio sources as either supernova remnants or HII regions. Long integrations at the H109a line frequency on two well-known supernova remnants (IC 443 and 3C 391) provide improved upper limits on the line emission from these objects. From these results the electron temperature in IC 443 is estimated to be in excess of 1�6 � 104 K.
The Radio Continuum of the Large Magellanic Cloud. I. The Sources at 6 cm Wavelength
Authors: McGee RX , Brooks JW , Batchelor RA
Published: June 2013

The Large Magellanic Cloud has been surveyed in the radio continuum at a wavelength of 6 cm with the 4' are beam of the Parkes radio telescope. A catalogue of 95 sources and diagrams of their brightness contours are presented here.
The Radio Continuum of the Large Magellanic Cloud. III. The Sources at 11 cm Wavelength
Authors: McGee RX , Brooks JW , Batchelor RA
Published: June 2013

A catalogue is given of radio sources observed in the Large Magellanic Cloud at 11 cm wavelength. A map of the radio brightness in the 30 Doradus region is included. The observations were made with a low-noise correlation radiometer and the Parkes 64 m radio telescope.
De-excitation Gamma Rays Following Photodisintegration of 28Si
Authors: Thomson JEM , Champion ND , Stewart RJJ , Thompson MN
Published: June 2013

Integrated cross sections for the population of excited states of 27AI and 27Si following photodisintegration of 28Si are presented. Consistency with particle pickup reactions is claimed as evidence of the single-particle nature of the photonuclear reaction in the giant resonance region.
A Thermodynamic Treatment of Anisotropic Diffusion in an Electric Field
Authors: Robson RE
Published: June 2013

Non-equilibrium thermodynamics is used to analyse the diffusive processes associated with a swarm of charged particles (ions or electrons) drifting in a neutral gas under the influence of an electric field. A simple approximate phenomenological relationship connecting components of the diffusion tensor with the drift velocity of the swarm is derived and the utility of the formula is illustrated in several cases where previous analyses have been carried out using the Boltzmann equation.
Optical Properties of Thin Germanium Films
Authors: Denton RE , Tomlin SG
Published: June 2013

The refractive and absorption indices of thin amorphous germanium films have been obtained from measurements, at normal incidence, of reflectances and transmittances over a wide range of wavelengths. The optical constants derived were in general agreement with the results of Tauc et al. (1964) except in the long wavelength region beyond the absorption edge. The absorption followed the law for indirect transitions from 0�72 to 1�1 eV, and the same law, but with a change in the slope of the curves, from 1�1 eV to the limit of our measurements at about 1�5 eV. The results are consistent with the view that the energy band structure of amorphous germanium is not essentially different from that of the crystalline material, except that the random structure eliminates the restriction that allows only direct transitions with the result that the absorption law for amorphous films is of the same form as for indirect transitions in crystals.
3+ States of 8Be
Authors: Barker FC , Ferdous Nasima
Published: June 2013

Level parameters for the 3+ doublet at about 19 MeV in "Be are obtained from a two-level R-matrix fit to the 7Li+p 5P3 phase shift, using the restrictions of the two-state isospin mixing model. The energy of the lower level is appreciably below the accepted value. Predicted contributions from the 3 + levels to the cross sections for the reactions 7Li(p, n), 7Li(p, y), lOBed, ex) and 9Be(d, t) are compared with measured values, and qualitative agreement is obtained. The new values of the level parameters give agreement with values of the isospin mixing matrix element and of the excitation energy difference of the 3 +, T = 1 states in "Li and "Be, calculated assuming that the charge-dependent nteraction is purely Coulomb.
Energy Loss by Energetic Test Ions in a Plasma
Authors: Hamada T
Published: June 2013

A study is made of the energy loss by an energetic (but nonrelativistic) test ion of charge Ze to plasma electrons in thermal equilibrium at temperature T. The classical region KT <{ Z2 Ry and the quantum region KT ~ Z2 Ry are both considered. The loss rates are given in closed form in terms of known functions of the ion speed. May's earlier work concerning the classical region is revised. Certain limiting cases are discussed in connection with the Bohr-Bethe-Bloch theory of the stopping power of ordinary matter.
Vibrations of Finite Linear Chains of Molecules
Authors: Mahany J , Deo BB
Published: June 2013

Szigeti's (1961) method for obtaining the vibration frequencies of a finite chain (representing a long-chain molecule) from those of an associated infinite chain is analysed by a matrix partitioning technique. It is shown that this method has the advantage of reducing the dimensionality of the secular determinant. The approach is illustrated by an example.
Aspects of the Exceptional Group E8
Authors: Wybourne BG
Published: June 2013

Methods for calculating branching rules and Kronecker products for the exceptional group E8 are developed. In particular, tables of branching rules for E8 -> SU9 , E8 -> SU2 X E7 and E8 -> SU3 X E6 are given. The third and fourth symmetrized powers of the adjoint representation of E8 are also resolved. The relevance of E8 to unified theories of strong, electromagnetic and weak interactions is briefly considered.
keV Neutron Capture Cross Section of 170Yb
Authors: Allen BJ , Cohen DD
Published: June 2013

The neutron capture cross section of 17�Yb has been measured relative to gold in the neutron energy range 10-70 ke V. The 30 ke V average cross section is 790 � 60 mb. The astrophysical significance of this result is discussed with respect to the 176Lu_176Hf cosmochronometer.
Mathematical Theory of One-dimensional Isothermal Blast Waves in a Magnetic Field
Authors: Lerche I
Published: June 2013

An investigation is made of the self-similar flow behind a one-dimensional blast wave from a planar explosion (situated on z = 0) in a medium whose density and magnetic field vary with distance as Z-W ahead of the blast front, with the assumption that the flow is isothermal. It is found that; if OJ OJ > 0 the governing equation possesses a set of movable critical points. For a weak, but nonzero, magnetic field it is shown that the value of the smallest critical point does not lie in the physical domain z > O. The post-shock fluid flow then cannot intersect the critical point, and is smoothly continuous. It is shown that to be physically acceptable, the fluid flow speed must pass through the origin. It is also shown that OJ must be less than t for the magnetic energy swept up by the blast wave to remain finite. The overall conclusion from the investigation is that the behaviour of isothermal blast waves in the presence of an ambient magnetic field differs substantially from the behaviour calculated for no magnetic field. These results point to the inadequacy of previous attempts to apply the theory of self-similar flows to evolving supernova remnants without making any allowance for the dynamical influence of magnetic field pressure.
LEED Peak Widths: a Fabry-Perot Etalon Analogue
Authors: Payling Richard , Ramsey JA , Turner RG
Published: June 2013

An analogy is drawn between the theory of the Fabry-Perot etalon for multiple reflections between two mirrors and that of the reflections between atomic layers with absorption in LEED. The analogy leads to an estimate of the LEED 'finesse', which in turn explains the widths and low intensities of LEED intensity versus voltage features. It is also shown that this explanation is consistent with the widely accepted Uncertainty Principle explanation.
Some Predictions from the Mean Field Equations of Magnetoconvection
Authors: Riahi N
Published: June 2013

Nonlinear magnetic convection is investigated by the mean field approximation. The boundary layer method is used assuming large Rayleigh number R for different ranges of the Chandrasekhar number Q. The heat flux F is determined for wavenumbers CXn which optimize F. It is shown that there are a finite number of modes in the ranges Q ~ R2/3 and R2/3 ~ Q ~ R, and that the number of modes increases with increasing Q in the former range and decreases with increasing Q in the latter range. For Q = 0(R2/3) there are infinitely many modes, and F is proportional to Rl/3 While the optimal F is independent of Q for Q ~ Rl/2, it is found to decrease with increasing Q in the range Rl/2 ~ Q ~ R and eventually to become of 0(1) as Q -> OCR), and the layer becomes stable.
The Haus-Tanaka Model for the Ice VII-Ice VIII Phase Transition
Authors: Ho-Ting-Hun J , Oitmaa J
Published: June 2013

The high temperature susceptibility series of the model proposed by Haus and Tanaka (1977) to account for the transition of the orientationally disordered ice VII phase to the orientationally ordered ice VIII phase does not provide evidence for the possible occurrence of a first-order transition, as predicted by the mean field approximation, but gives a second-order transition instead.
Cosmic Rays in the Galactic Centre
Authors: Yoshimori Masato
Published: June 2013

The cosmic ray flux in the galactic centre region is predicted from the observed data for high energy y rays, y-ray lines and massive molecular clouds. The predicted cosmic ray fluxes above 1 GeVand below 100 MeV are two and four orders of magnitude respectively larger than the value in the neighbourhood of the solar system. The corresponding energy density of cosmic rays is estimated to be 100 eV cm- 3 ? Such a concentrated stream of cosmic rays could accelerate the dense and massive molecular clouds by transfer of their momentum.
D(d,n)3He Differential Cross Sections from 18 to 26 MeV
Authors: Jones AB
Published: June 2013

Angular distributions of the D(d, n)3He reaction have been measured for incident deuteron energies of 18, 20, 22, 24 and 26 MeV. The data provide no evidence for the proposed broad level in 4He at approximately 30 MeV.
Some Characteristics of the Interactions of 1·9 GeVn-1 Iron Nuclei with Photographic Emulsion
Authors: McCusker CBA
Published: June 2013

We have scanned 18 �06 m of track of [�9 OeV n- 1 iron nuclei accelerated at the Bevalac and passing through Ilford 05 nuclear research emulsion. From the 233 interactions found, details are given here of mean free paths and fragmentation parameters for various types of event.
Relation Between Polynomials Orthogonal with Respect to a Class of Gaussian Weight Functions
Authors: Kumar Kailash
Published: June 2013

Polynomials of a three-dimensional vector x, orthogonal with respect to a weight function ~exp( -tx2) and expressed in spherical polar coordinates, are called Burnett functions. The matrix relating the Burnett functions of x = IX(C- W) to those of c is constructed for the case where IX is a real nonsingular 3 x 3 matrix and W is a real vector. These matrices are infinite dimensional, block lower triangular representations of the group whose elements (IX, W) satisfy the composition law
Is Nuclear Physics the Molecular Physics of Coloured Quarks?
Authors: Freeman Geoffrey , HJ McKellar Bruce
Published: June 2013

We show that nuclear physics provides evidence against the existence of hadronic Van der Waals forces between nucleons.
Neutron Diffraction ? The Total Powder Pattern
Authors: Sabine TM
Published: June 2013

The value of the ordinate of a neutron powder pattern is expressed as the sum of Bragg scattering, due to the existence of an average lattice, and diffuse scattering, due to local deviations from the average lattice. In this form the calculated pattern can be refined by least squares methods against the observed pattern to give both average structural parameters and disorder parameters. Significant advantages over the use of only Bragg scattering for the determination of structural parameters are: (1) a powerful limit on the value of the temperature factor is imposed by the condition that neutrons removed from Bragg peaks must be accounted for in the diffuse scattering; (2) correlation between partially occupied sites can be found. The cross sections for Bragg and disorder scattering are given.
Accretion of Planetesimals within a Gaseous Ring
Authors: Prentice AJR
Published: June 2013

An analytical study is made of the accretion of planetesimals by a planetary embryo within the framework of a modem Laplacian theory for the formation of the planetary system. The equation of motion of the particle, which is initially comoving ahead of (or behind) the growing planet on the same circular Keplerian orbit about the Sun, is examined both in the presence and abseflce of a gaseous torus which is also centred on the same mean orbit. The gas density in the torus is taken to be uniform and the drag exerted on the particle is assumed to vary as the square of the relative velocity, corresponding to motion at high Reynolds number. It is found that the gas acts as a damper to the coriolis acceleration due to the Sun in the rotating frame of reference of the embryo, which tends to pull the particle off the mean circular orbit, thus preventing accretion. In the absence of the gaseous drag, less than 1 % of particles lying well inside the so-called sphere of gravitational influence of the embryo are accreted, whilst if the gas drag is included nearly all of these particles are captured. In all instances the accreting particles impart a spin angular momentum to the embryo which is prograde with the orbital motion. The actual spin rate decreases with increasing gas drag and is found to be lowest for the innermost planets Mercury and Venus, where the gas density is greatest. A more detailed numerical study is probably required to determine the rotational period of larger planets and planetary cores which possess an outer atmosphere, not included in the p$ent study, and where nonlinear effects in the particle's equation of motion cannot be ignored.' 'r.'
Quantum Theory of Energy Loss by Test Ions to Plasma
Authors: Hamada T , Nakamura Y , George EP
Published: June 2013

A fully quantum theoretical calculation is carried out for the average energy loss rate by test ions released in a plasma. The calculation is based on the divergence-free kinetic theory of Kihara and Honda. The rate is given in terms of several auxiliary functions which may be evaluated numerically for a given test ion once the Maxwellian temperatures and densities of each plasma species (electrons and ions) are specified. The examples considered earlier by Sigmar and Joyce are re-evaluated and the accuracies of their approximate calculations are found to be generally quite good. Several new quantitative results are presented.
Numerical Modelling of Climate
Authors: Hunt BG
Published: June 2013

Numerous ways of modelling climate exist, ranging from a single, simple mathematical equation up to complex global atmospheric--oceanic coupled models which explicitly forecast the basic weather elements such as temperature, pressure, wind velocity etc. These models, known as general circulation models, currently provide the most comprehensive and credible representations of climatic systems. The structure of these models is briefly outlined, and results from a number of models are presented to illustrate their versatility. A number of other simpler modelling approaches to climate are discussed to emphasize the opportunities which this problem presents for creative and rewarding research.
Colour?Spin Matrix Elements for Multiquark Systems
Authors: Bickerstaff RP , Wybourne BG
Published: June 2013

Tensor operator methods have been developed for calculating the matrix elements of the two-particle colour-spin operator that arises in the calculation of the quark-gluon interaction in the MIT bagmodel treatment of the S-wave colour singlet states of multiquark hadrons. A group classification scheme for multi quark states which distinguishes the nonstrange and strange quarks, and thus avoids the occurrence of hidden strangeness ss pairs, is constructed. This scheme has the added advantage of avoiding any need to approximate the strangeness dependence of the relevant interaction integrals. The colour-spin matrix elements for all the q4 if colour singlet states and for the strangeness - 2 states of q6 are given by way of examples. A number of checking procedures have been developed to ensure the correctness of the calculated matrix elements.
Electron Transport in Argon - Hydrogen Mixtures
Authors: Haddad GN , Crompton RW
Published: June 2013

The transport coefficients υdr and D⊥/μ have been measured in mixtures of 0.5 % and 4 % hydrogen in argon. All measurements were made at 293 K. It is shown that for these mixtures the use of the solution of the Boltzmann equation based on the two-term Legendre expansion of the velocity distribution function introduces no significant error in the analysis of the transport data. All the experimental data have been predicted to within � 3.5 % using previously published cross section data.
A New Deconvolution Method for Data Analysis in Translational Spectroscopy
Authors: Goh SC
Published: June 2013

A new method is presented for the deconvolution of molecular dissociation data obtained by translational spectroscopy, and this is applied to the 1000 eV collision-induced dissociation of H2+ and HeH+.
Boundary Effects in Solution of Boltzmann's Equation for Electron Swarms
Authors: Robson RE
Published: June 2013

The combined effect of interaction of electrons with walls, neutral molecules and an electrostatic field is considered through analytic solution of Boltzmann's equation. In the first instance, we discuss a half-range decomposition in velocity space, corresponding to electrons moving to and from the walls, which is valid for all types of electron-molecule interactions. The half-range equations are solved in the steady state for zero field and the constant mean free path model, and it is shown that the familiar full-range 'two-term' approximation equations are adequate in this case, as far as estimating bulk properties of the electrons is concerned. For the nonzero field, again in the steady state, the full-range equations are solved for the constant collision frequency model.
The Effects of Anisotropic Scattering on Electron Transport
Authors: Haddad GN , Lin SL , Robson RE
Published: June 2013

The recently developed theory of Lin et al. has been used to make a systematic study of calculated electron drift velocities and diffusion coefficients. Differences between the usual two-term solution and the converged results are calculated for a number of cases to demonstrate the effects of anisotropic scattering on the interpretation of swarm experiments.
The Photoneutron Cross Section of 44Ca
Authors: Harty PD , Thompson MN
Published: June 2013

Measurement of the photoneutron cross section 44Ca(y, n,) has been made over the photon energy range 11-26 MeV. Comparison with the 44Ca(y, p) cross section shows evidence for isospin splitting of the giant dipole resonance (GDR) in agreement with predictions. Some evidence has also been found for deformation splitting of the'44Ca GDR.
Resonance Neutron Capture in 86,87Sr
Authors: Hicks GC , Allen BJ , de L Musgrove AR , Macklin RL
Published: June 2013

The neutron capture cross sections of 86.87Sr have been measured with high energy resolution from 3 to 200 keY at the 40 m station of the Oak Ridge Electron Linear Accelerator. Individual resonances were analysed to 37 keY for 86Sr and to 14 keY for 87Sr, and average resonance parameters were deduced on the basis of assumed divisions between s- and p-wave resonances. The average radiative widths obtained on this basis are consistent with a capture mechanism which is predominantly statistical
The Giant Dipole Resonance Effect in Coulomb Excitation of 10B
Authors: Vermeer WJ , Zabel TH , Esat MT , Kuehner JA , Spear RH , Baxter AM
Published: June 2013

Coulomb excitation of the O' 718 MeV, In = 1 +, first excited state of lOB has been studied using projectile excitation by 208Pb and observing the backward scattered particles. The results give a clear indication of the virtual excitation of the giant dipole resonance (GDR) as a second-order effect. The observed magnitude is consistent with the usual hydrodynamic model estimate and with a recent shell-model calculation.
The Theory and Computational Implementation of Quadratically Convergent Hartree-Fock Orbital Optimization Methods and Their Relationship to the Time-dependent Hartree-Fock and RPA Methods
Authors: B Bacskay George
Published: June 2013

The theory of quadratically convergent Hartree-Fock or self-consistent field (QC-SCF) orbital optimization is presented using the language of second quantization. Two methods that are appropriate for the computational implementation of QC-SCF are described: the Newton-Raphson method and an approximate super configuration interaction (CI) approach, both of which can be implemented such that no four-index transformation is necessary.
An Algebraic Description of Perturbation Theory in Quantum Electrodynamics
Authors: Wright JD
Published: June 2013

We use an algebraic formulation of the electromagnetic field, in which various quantization procedures can be described, to discuss perturbation calculations. We show that the Feynman rules and the second order calculation of the self-energy of the electron can be developed on the basis of the Fermi method of quantization. The algebraic approach clarifies the problems in defining the vacuum and other states, which are associated with calculations in terms of field algebra operators. We demonstrate that the 'vacuum' state defined on the field algebra by Schwinger leads to incorrect results in the self-energy calculation.
Nuclear Magnetic Resonance Imaging
Authors: Pope JM
Published: June 2013

The principles of two new techniques of medical physics, nuclear magnetic resonance (NMR) imaging and topical magnetic resonance, are outlined. Progress in the development of these techniques and their application in clinical trials is reviewed. Advantages of NMR methods over existing imaging modalities are discussed. Finally some safety aspects are considered.
The Spatial Alfvén Resonance in a Collisional Plasma
Authors: Donnelly IJ , Clancy BE
Published: June 2013

The structure of wave fields at the spatial Alfven resonance in a cylindrical collisional plasma is studied using both a WKB analysis and a numerical solution of the wave equations. At high plasma density and low temperature the Alfven resonance leads to ohmic dissipation of wave energy in a narrow resistive layer. The enhanced b. fields in this layer allow detection of the Alfven resonance position by magnetic field probes. An experiment which reports the observation of the spatial Alfven resonance has been analysed with good agreement between the calculated and the measured fields.
The Effect of Lattice Discreteness on the Linewidth of the Electron Spin Resonance of Local Moments in Metals
Authors: Stewart AM
Published: June 2013

Solutions of the Hasegawa-Bloch equations for the electron spin resonance of local moments in metals are obtained which take account of the discrete nature of the lattice. The most notable result derived is that the resonance linewidth is proportional to T - () for any degree of bottlenecking, where () is the paramagnetic Curie temperature calculated with lattice discreteness. An alternative derivation of the appropriate Hasegawa-Bloch equations is also given.
A Fast-response EBIC System
Authors: Rossouw CJ , Maher FJ , Panjkov AA
Published: June 2013

The application of the EBIC technique in the study of electrical activity of defects in semiconductors is discussed, with particular reference to instrumentation. A fast-response current amplifier, built in our Division, is shown to be more than adequate for most EBIC applications. Some examples of EBIC analysis are presented.
The Excitation of Ion-acoustic Waves by a Magnetic Pump in Cylindrical Geometry
Authors: Cramer NF , Donnelly IJ
Published: June 2013

The modulational, parametric and purely 8rowing mode instabilities of a magnetic pump with a finite radial wavenumber in cylindrical geometry are investigated. The modulational instability is compared with the instability of a parallel propagating pump wave, and the growth rates are found to be similar. The growth rate of a pair of ion-acoustic waves is shown to be zero for a collisionless plasma, in agreement with less general results found previously. The growth rate in the collisional case is found to be nonzero. The purely growing mode growth rate is calculated for excitation of ionacoustic plus torsional Alfven waves.
Phonon Dispersion Relations for Caesium Thiocyanate
Authors: Irving MA , Elcombe MM , Smith TF
Published: June 2013

Room temperature phonon dispersion relations for frequencies below 2 THz have been measured, along the three orthorhombic axes and selected diagonal directions by neutron inelastic scattering, for caesium thiocyanate. These curves, which represent 13 acoustic modes and 11 optic modes of vibration, do not agree with the dispersion behaviour calculated from the rigid-ion model developed by Ti and Ra to describe their Raman scattering observations.
Examination of a Proposed Technique for the Economical Detection and Analysis of Ultra-high Energy Cosmic Ray Showers
Authors: Clay RW , Dawson BR
Published: June 2013

A study has been made of a recently suggested scheme for the economical detection and analysis of ultra-high energy cosmic ray showers. It is demonstrated that the scheme should be feasible, particularly if detectors are used to sample the y-ray component of the showers.
Proton Inelastic Scattering in the Interacting Boson Model: Formalism and Application to the Ge Isotopes
Authors: Bauhoff W , Morrison I
Published: June 2013

The application of the interacting boson model to the coupled channel description of inelastic proton scattering is studied. The radial shape of the transition potentials is determined by analogy to the usual geometrical models, whereas the reduced matrix elements are calculated from the boson Hamiltonian. The general formalism is applied to scattering from the Ge isotopes. We find a better description for the heavier isotopes in terms of an O(6)-symmetric model than for a vibrational model.
The Steady Currents Driven in a Conducting Sphere Placed in a Rotating Magnetic Field
Authors: Hugrass WN , Kirolous HA
Published: June 2013

The steady currents (and the associated steady magnetic fields) generated in a conducting sphere placed in a rotating magnetic field are calculated in the weakly nonlinear limit. It is found that the steady driven current has a poloidal and a toroidal component. The steady toroidal magnetic field associated with the driven poloidal current has opposite senses above and below the equatorial plane; the net toroidal flux is zero. The relevance of this result to some recent observations in the Rotamak experiment is discussed.
Pulsed Field Gradient Nuclear Magnetic Resonance as a Probe of Liquid State Molecular Organization
Authors: Callaghan PT
Published: June 2013

The imposition of magnetic field gradients on a nuclear magnetic resonance experiment imparts a spatial tag to the molecules via the Larmor frequencies of the nuclei (commonly protons) within. A sensitive measure of changes in the frequency distribution is afforded by detecting the loss of phase coherence in a spin-echo experiment performed in the presence of gradient pulses. Here the molecular displacements may be measured over the duration given by the pulse separation. Pulsed field gradient nuclear magnetic resonance (PFGNMR) employs timesca1es of tens of milliseconds and has a displacement sensitivity of the order 100 nm.
Changes in the Frequency Distribution Characteristics of Ionosonde Es Parameters During Major Meteor Activity
Authors: Baggaley WJ
Published: June 2013

The probability of occurrence of both 10 E, and Ib Es in excess of ionosonde limiting frequency has been examined for two Southern Hemisphere stations at periods of recurrent annual meteor shower activity and periods of no shower influx. The analyses show that marked changes occur in probabilities for high values of!o Es and Ib Es indicating structural modifications to Es layers.
Gyromagnetic Emission and Absorption: Approximate Formulas of Wide Validity
Authors: Robinson PA , Melrose DB
Published: June 2013

Approximate formulas of wide validity are derived for gyro magnetic emission and absorption of gyromagnetic waves by mildly relativistic electrons. An averaged emissivity is defined by replacing the sum over harmonic number by an integral and averaging over the pitch angle distribution of the radiating particles. A method for performing the average over pitch angle without approximation to the Bessel functions is developed and the resulting expressions are then approximated using Wild-Hill formulas which interpolate between the non-relativistic and ultra-relativistic limits.
Bound on the Number of Flavours
Authors: Christos GA
Published: June 2013

If one imposes the permutation symmetry S. (n is the number of lepton flavours) reducibly on. the different families (e, /1, r, ... ), it follows that at least two leptons have the same mass if n > 6. If equal lepton masses are excluded, this implies a bound on the number of flavours.
The Room Temperature Elastic Behaviour of CsH2PO4
Authors: Prawer S , Smith TF , Finlayson TR
Published: June 2013

The components of the elastic constant matrix of monoclinic caesium dihydrogen phosphate (CDP) have been determined using ultrasonic velocity measurements to be Cl1 = 28� 83 � 0 '43, C22 = 26�67 � O� 37, C33 = 65 �45 � 0'48, C44 = 8 .1O� 0,15, Css = 5 �20� 0,24, C66 = 9�17 � 0,22, C12 = 1l'4�3'6, C13 = 42�87�1�58, CIS = 5'13�0'67, C23 = 14�5�4�4, C 2S = 8'4�4'3, C3S = 7�50�0�81 and C46 = -2�25�0�31 GPa. Calculations of the velocity surfaces, ray directions, Young's modulus surfaces and linear compressibility show marked elastic anisotropy, which has been correlated with the chain and layer-like structure of CDP.
Neutron Diffraction Studies of CsSCN above Room Temperature
Authors: Irving MA , Elcombe MM , Smith TF
Published: June 2013

Neutron diffraction studies have been made on the orthorhombic phase of caesium thiocyanate for temperatures below the order-disorder phase transition at 470 K. The structure, as determined at 453 K by elastic neutron diffraction, is found to be very similar to that at room temperature. This behaviour is contrasted with that of potassium thiocyanate. The temperature dependences of the acoustic phonon dispersion branches, as determined by inelastic neutron diffraction, are also presented for temperatures up to 463 K. No evidenq: of significant mode softening was observed.
Quantum-statistical Analysis of Low Energy Sputtering
Authors: Wilhelm HE
Published: June 2013

Low energy surface sputtering of polycrystalline metals is explained theoretically by means of a three-body sputtering mechanism involving the impinging ion and two metal atoms. By means of quantum-statistical methods, a formula for the number S(E) of atoms sputtered on the average by an ion of energy E is derived from first principles. The theory agrees with experimental sputtering data in the low energy region above the threshold. As an application, mercury-metal atom scattering cross sections are determined by quantitative comparison of the theoretical and experimental S(E) values for sputtering mercury ions from various metals.
Dynamics of a Nonlinear Diatomic Chain. II. Thermodynamic Properties
Authors: Henry BI , Oitmaa J
Published: June 2013

We compute the free energy density of a nonlinear diatomic model for a solid which may undergo a displacive structural phase transition using (i) a two-component transfer integral operator equation and (ii) an ideal gas phenomenology incorporating the stable solutions of the coupled Euler-Lagrange equations as elementary excitations. The agreement between the two calculations formally establishes that the low temperature excitation spectrum is dominated by both the familiar linearized phonon solutions and by nonlinear domain wall or kink soliton solutions. The ideal gas phenomenology is then used to compute the kink density, order parameter correlation functions, and the kink contribution to the dynamical structure factor. The dynamical structure factor is found to exhibit a central peak.
Dynamics of a Nonlinear Diatomic Chain. III. A Molecular Dynamics Study
Authors: Henry BI , Oitmaa J
Published: June 2013

We investigate the dynamics and the statistical mechanics of a nonlinear diatomic model for a solid which may undergo a displacive structural phase transition (DSPT), using the molecular dynamics (MD) technique. Snapshots of the lattice displacement pattern reveal the presence of kinks at low temperatures. MD collision experiments show that the kinks exhibit soliton-like behaviour. Phonon wave packets are observed to pass through kinks and kinks and anti-kinks interact with one another with little distortion. The MD data are used to calculate the dynamical structure factor for the displacement fields in the diatomic chain. The dynamical structure factor is found to exhibit a central peak when the lattice displacement pattern is dominated by kinks. At small but finite wave vectors the central peak splits producing a new excitation branch in addition to the usual soft-mode phonon side-band. The central peak does not arise from self-consistent phonons but is dependent on the presence of kinks. The height of the peak increases and the width of the peak decreases as the temperature goes to zero.
Bianchi Type I Cosmological Models with Perfect Fluid and Magnetic Field
Authors: Roy SR , Narain S , Singh JP
Published: June 2013

We investigate Bianchi type I cosmological models containing a perfect fluid and with an incident magnetic field directed along the x axis. The solutions obtained represent an expansion scalar B bearing a constant ratio to the anisotropy in the direction of a space-like unit vector At.
Atomic Charges and Electron Density Partitioning
Authors: Maslen EN , Spackman MA
Published: June 2013

Atomic charges are derived from two dissimilar methods of partitioning the electron density of diatomic molecules. The results given by both methods are similar, with the exception of those for molecules containing lithium; factors responsible for this discrepancy are explored. The charges derived are correlated closely with electronegativity differences and with dipole moments. They follow chemically sensible trends and have reasonable magnitudes. The partitioning methods used in the derivation can also be applied to the analysis of diffraction data for crystalline solids.
Determination of B(E3; 01+ ? 31-) Values for the Stable Isotopes of Cadmium
Authors: Fewell MP , Spear RH , Adam GK , Esat MT
Published: June 2013

Values of B(E3; ot --+31) for the stable isotopes of Cd have been determined from particle spectra obtained using Coulomb excitation by 160 projectiles. The results are: 0�16 �O �04 e2 b3 (106Cd), 0.150�0.01O e2 b3 (108Cd), 0.1l5�0.013 e2 b3 (llOCd), 0.1l4�0.009 e2 b3 e12 Cd), 0.131 �0�015 'e2 b3 (114Cd) and 0-l00�0.01l e2b3 (1l6Cd). The corresponding E3 strengths are 34, 31,23,22,24 and 18 single particle units (s.p.u.) respectively. Examination of these and other data reveals no evidence for shell effects in B(E3; ot --+31) values near the Z = 50 proton shell, in contrast to the situation for B(E2; ot --+2 t) values.
Reflection of Magnetoionic Waves from a Steep Density Gradient. II. Incident Ordinary Mode
Authors: Hayes LM
Published: June 2013

We consider the case of an ordinary mode wave incident on a density discontinuity in an anisotropic plasma. The relative magnitudes of the two transmitted and two reflected modes produced by the incident 0 mode are calculated, and the dominant secondary mode is determined for different incident wave parameters and plasma parameters. An application of this work to the interpretation of the polarization of certain solar radio bursts is considered.
Oscillations in Sunspots
Authors: H Thomas John
Published: June 2013

Recent observational and theoretical work on oscillations in sunspots is reviewed. The characteristic 3-minute umbral oscillations and flashes are reSonant modes of the sunspot itself, whereas the 5-minute oscillations in the umbra are a passive response to forcing by p modes in the surrounding convection zone. The observational evidence suggests that the fundamental cause of the 3-minute oscillations is the photospheric fast-mode resonance, with chromospheric slow-mode resonances perhaps producing additional oscillation frequencies in the chromosphere. Observations and theoretical models of the interaction of 5-minute p-mode oscillations with a sunspot offer a means of probing the structure of a sunspot magnetic flux tube beneath the solar surface. The observed differences between running penumbral waves in the chromosphere and in the photosphere may be explained by the effect of the Evershed flow on trapped magneto-atmospheric waves in the penumbra.
Superallowed Fermi b Decays, CVC and Universality
Authors: Jaus W , Rasche G
Published: June 2013

A review is given of the present status of superallowed Fermi /3 decays including a short discussion of the radiative corrections of order a, Za2, Z2a 3 and of nuclear effects. We also point out that the interaction of the emitted positron with the magneto static field of the spectator nucleons induces additional corrections of about 0�1 % to the ft values. Despite refinements in the calculation of the theoretical corrections, there is a remaining discrepancy between the It values which is even larger than the theoretical uncertainties. This behaviour of the It values is not understood at present.
The Application of Blanc's Law to the Determination of the Diffusion Coefficients for Thermal Electrons in Gases
Authors: Lj Petrovic Zoran
Published: June 2013

Blanc's law is exactly applicable when the momentum transfer cross sections for electrons in each constituent of a gas mixture have the same energy dependence in the relevant energy range. This condition is rarely satisfied even for thermal energies. In this paper the magnitude of the errors arising from the applications of Blanc's law is examined for some cases where the condition is strongly violated, and a procedure developed for obtaining useful data from its application even under these circumstances.
The Large Numbers Hypothesis and a Relativistic Theory of Gravitation
Authors: Lau YK , Prokhovnik SJ
Published: June 2013

A way to reconcile Dirac's large numbers hypothesis and Einstein's theory of gravitation wasrecently suggested by Lau (1985). It is characterized by the conjecture of a time-dependentcosmological term and gravitational term in Einstein's field equations. Motivated by thisconjecture and the large numbers hypothesis, we formulate here a scalar-tensor theory in terms of an action principle. The cosmological term is required to be spatially dependent as well as time dependent in general. The theory developed is applied to a cosmological model compatible with the large numbers' hypothesis. The time-dependent form of the cosmological term and the scalar potential are then deduced. A possible explanation of the smallness of the cosmological term is also given and the possible significance of the scalar field is speculated.