bluuebunny/crossref_metadata_2025 huggingface dataset:
The Stress Fields Around Some Dislocation Arrays
Authors: Head AK
Published: May 2011

The stress fields around some edge dislocation arrays have been calculated using the approximation of Leibfried (1951) that the discrete dislocations are replaced by a continuous dislocation density. Haasen and Leibfried (1954) have calculated one such stress distribution (corresponding to (ti) below) via the stress function which they evaluated as a superposition integral over the dislocation distribution of the stress function of an infinitesimal dislocation. The results given here were evaluated directly as the superposition of the stress fields of the infinitesimal dislocations making up the distribution. Like most of the integrals which occur in this approximation, they can be evaluated most readily by contour integration (Haasen and Leibfried 1954). A multiple coordinate system is used and is such that the results can be written compactly and approximations and limiting cases can be easily obtained.
The Optimum Line Width for a Reflection Cavity Maser
Authors: Troup GJ
Published: May 2011

It has been pointed out previously (Troup 1959, hereinafter referred to as I) that there is an optimum line width for the transition used in a reflection cavity maser and that this optimum line width gives maximum bandwidth for a given gain. However, it was not explicitly deduced in I that this optimum line width actually gives the maximum value of (Gain)l xBandwidth product for a given cavity maser system. This note makes the appropriate deduction.
Photoprotons from Tantalum
Authors: Carver JH , Taylor RB , Turchinetz W
Published: May 2011

Photoproton emission from tantalum has been studied by measuring the yield of the 5�5 hr isomer of 180Hf produced in the 181Ta(y,p)180mHf reaction. The experimental arrangements were similar to those used in a previous investigation (Oarver and Turchinetz 1958) of the photodisintegration of tantalum, except that the shielding of the scintillation counter, a It in. diameter by 2 in. long NaI(Tl) crystal, has now been improved along the lines described by Pringle, Hollander, and Seaborg 1958}
A Novel Type of High Power Pulse Transmitter
Authors: Landecker K , Imrie KS
Published: May 2011

A system of generation of radio waves is described which makes use of a symmetrical circular array of condensers charged through resistors and discharged through spark gaps in the manner of the Marx impulse generator. It is shown that exponential wave� trains of very high peak powers, of the order of 10,000 MW, may be radiated. The radiation resistance and radiation field of the structure are given and modification of the field pattern by parasitic elements is considered. Formulae and graphical aids are given which facilitate the design of such transmitters and experiments with various model transmitters are described. Consideration is given to circuit losses, particularly spark losses, and means are described to minimize these losses.
An Interferometer for the Measurement of Radio Source Sizes
Authors: Goddard BR , Watkinson A , Mills BY
Published: May 2011

Modifications have been made to the 85�5 Mc/s cross-type radio telescope at Sydney to permit the measurement of radio source sizes in the range of 10' to l' arc. The basic modification involves the addition of another aerial at a distant site connected by radio link. A new form of automatic gain control ensures very good stability for the system. The modified instrument is described in general terms and calibration techniques are discussed.
A Catalogue of Radio Sources Between Declinations ?20° and ?50°
Authors: Mills BY , Slee OB , Hill ER
Published: May 2011

A catalogue has been prepared of the radio sources observed between declinations _200 and _500 , using the Sydney cross-type radio telescope at a wavelength of 3�5 m ; a total of 892 sources is listed. This supplements an earlier catalogue in the declination zone + 10� to _20�. In addition to the positions and intensities of the sources, angular sizes of 50 of the strongest are given: several are found to have a size less than 15" arc. As before, identifications with bright optical objects have been sought, and a number of galaxies of apparently abnormal radio emission listed. Statistical analyses of the distribution of the radio sources give results very similar to those obtained using the earlier catalogue. \Vithin the uncertainty in the data, the distribution appears uniform in depth and there is a siguificantly greater number of sources of large apparent size than expected from chance blending effects.
Direction?Finding on Diffuse Sources of Electromagnetic Radiation
Authors: Cartwright DG
Published: May 2011

It is shown that, for sources of large angular size, the response of an Adcock type direction�finder is independent of the extent of the source in altitude. On the other hand, the response of a rotating loop does depend on altitude. By combining the characteristics of both types of direction-finder, the position and size of an extended source can be found, provided that a brightness profile can be assumed.
The General Theory of the Motions of Ions and Electrons in Gases
Authors: Huxley LGH
Published: May 2011

In this paper the more important general formulae for the drift velocities and diffusion coefficients of ions and electrons in gases are derived by the application of dynamical principles. These formulae agree with those already established by a proper application of the method of free paths. Formulae for the distribution of speeds of agitation are also derived.
A System for Recording and Integrating Physical Measurements
Authors: Rider NE
Published: May 2011

Many occasions occur when it is required to make recordings of one or more fluctuating physical quantities. When the measurements to be made, either of the same quantity at a number of positions or of various quantities at one position, .exceed quite a small number, continuous recording is not a practical proposition. In any event it may not be necessary. The frequency with which it would be desirable to record a particular measurement will depend on: (a) the expected rate of fluctuation of the quantity concerned having regard to smoothing that may be introduced by the primary sensing device and the recorder in use; (b) the magnitude of the expected fluctuations, again almost certainly modified by the apparatus; (c) the resolution available in a single measurement; (d) the accuracy to which a time mean value is required together with the time over which the mean is to be taken.
n-Diffusion
Authors: Philip JR
Published: May 2011

Transfer processes in which an entity is transferred down a gradient of a concentration- like quantity satisfy the relation q=-A.B, with q the flux density, A dependent on time, concentration and position, and B a function of the concentration gradient, \76.
On Solving the Equation of Radiative Transfer for Conservative Non-uniform Media
Authors: Wilson PR
Published: May 2011

The equation of radiative transfer in a form suitable for non-uniform semi-infinite media in radiative equilibrium is solved for the attenuation coefficient x compatible with models for total intensity J as functions of two variables, subject to the boundary condition of zero inward flux at the surface.
Wavelengths of Krypton 86, Mercury 198, and Cadmium 114
Authors: Bruce CF , Hill RM
Published: May 2011

The vacuum wavelengths and the spectral line profiles of four lines of krypton 86, four lines of mercury 198, and four lines of cadmium 114 have been measured. One line, the radiation 2PlO-5d5 of krypton 86 (6057 At has been used as the reference standard in the wavelength measurements.
The Distribution of Meteor Masses for Sporadic Meteors and Three Showers
Authors: Weiss AA
Published: May 2011

Distributions of maximum line densities (OI:max. electrons/cm) in meteor trails,
and hence distributions of meteor masses, are derived from radio-echo data for sporadic
and shower meteors.
Estimation of the Maximum Temperature in a Radially Constricted Gas Discharge Between Electrodes
Authors: Seymour PW
Published: May 2011

A steady-state deuterium discharge between two electrodes is considered and the free boundary surface of the plasma is assumed thermally insulated when pinched away from the walls of the discharge tube. Cooling is therefore by heat conduction to the electrodes, compared to which bremsstrahlung loss is shown to be negligible if the discharge is not too long. The main question examined is how much the maximum temperature T m can be raised by constricting the cross section of the discharge near the centre.
The Gradation and Inertia of Hurter and Driffield: A Study in Theory
Authors: Candler C
Published: May 2011

In a deep emulsion the shape of the D-Iog E characteristic depends on two quantities, the photon number P, which is determined by the number of photons required to form a development centre, and the ratio K of the absorption cross sections of a silver halide crystal before and after development. The position of the curve on the exposure axis is determined by the mean reaction cross section 8 of the crystals. In a coating a fourth quantity enters, the" opacity before development" of Hurter and Driffield, here called the exposure ratio R of front to back surface.
Resolution of Bremsstrahlung Experiments
Authors: Thies HH
Published: May 2011

This paper investigates how mathematical approximations and statistical errors are transmitted into computed cross sections in the analysis of experimental bremsstrahlung yield data. The resolution of bremsstrahlung experiments is defined in analogy with optical resolution and an expression for the practical evaluation of resolution is derived. Methods of cross-section computation, and smoothing and curve-fitting are discussed.
Vertical Velocities in the Solar Chromosphere
Authors: Giovanelli RG , Jefferies JT
Published: May 2011

A t A birefringent filter has been used to photograph the chromosphere at various wavelengths across the HI)( line. A process of photographic subtraction has then yielded photographs of velocity distributions. At all chromo spheric depths, there is a close correlation between the intensity of the granules in HI)( and the vertical velocity, the darker granules falling.
A Sky Survey of Neutral Hydrogen at l 21 cm. I. The General Distribution and Motions of the Local Gas
Authors: McGee RX , Murray JD
Published: May 2011

A survey for neutral hydrogen of the whole sky visible from Sydney has been carried out with a multichannel H-line receiver and a 2�.2 aerial beam. A sample of the profiles obtained has been analysed to present the disposition of local hydrogen in terms of three schematic diagrams: (1) the distribution of N H, the number of hydrogen atoms in a line-of-sight column of 1 cm" section, (2) a diagram of representative line halfwidths, and (3) the observed distribution of profile peak radial velocities.
The 5577 Å OI Emission Line of the Airglow at Brisbane
Authors: Danziger IJ
Published: May 2011

During the four-month period from April to July 1960, a two-colour airglow photometer of the Huruhata type (Huruhata, Nakamura, and Tanabe 1957), recorded intensities of the night-sky emission at 5577 and 5300 A at Brisbane (geographic latitude 27� 30' S., longitude 153� 06' E., and geomagnetic latitude 35� 06' S.). A total of 156 hr of recording during 19 nights was obtained. A complete sky survey was made each 16 min. The corrections for van Rhijn variation and atmospheric extinction were applied in the analysis.
Charged Particle Trajectories in Static Electric and Magnetic Fields
Authors: Ausburn KJ
Published: May 2011

A trajectory passing through a given point in a given direction is completely determined if its curvature and torsion are known functions of its arc length. Relativistic expressions for the curvature and torsion in terms of the electric and magnetic field distributions are derived below. Besides their intrinsic interest these expressions may be useful in the analytical solution of some simple trajectory problems.
An Exact Solution to a Problem in Heat Transfer
Authors: Johnson CHJ
Published: May 2011

In order to determine the complete temperature history in problems concerning the transfer of heat from a moving fluid to a solid body one is obliged, in general, to solve both the flow and heat transport equations for the fluid and the heat conduction equation for the solid. Analytical solutions to this problem cannot in general be given owing to the (non-linear) way in which the flow and heat transport equations for the fluid are coupled.
Phenomena Accompanying the Birth of Sunspot Pores
Authors: Loughhead RE , Bray RJ
Published: May 2011

Disturbances in the photospheric granulation accompanying the birth and development of some sunspot pores are illustrated (Plate 1) and described. The disturbances last for about 3 hr and take the form of a number of dark lanes lying between two groups of pores whose location with respect to the rest of the spot group suggests that they are of opposite magne1;ic polarities.
Deviations from Matthiessen's Rule for Platinum
Authors: Klemens PG , Lowenthal GC
Published: May 2011

An analysis of the resistivity-temperature relationship down to liquid helium temperatures of 17 platinum resistors as determined in various laboratories shows that deviations from Matthiessen's rule can be classed roughly into three groups. One of them follows the pattern predicted by Sondheimer and Wilson's theory. The other two cannot be fully explained in this way, and may be due to the sensitivity of the electronic band structure of transition metals to small concentrations of impurities. The behaviour of a resistor thus depends on the nature as well as the total amount of impurities and imperfection~. In low temperature platinum resistance thermometry the resistors should be selected with regard to the type of residual impurity as well as total impurity content.
Luminescence in KI:Tl
Authors: Alderson JE , Williams SE
Published: May 2011

Freshly cleaved single crystals of KI:TI containing various concentrations of Tl have been irradiated in a vacuum monochromator in the 2800-1100 A region at temper. atures between -140 and 45 �0. The relative luminescence efficiencies in the Tl absorption bands and the host crystal fundamental absorption show that energy is transferred from host crystal to impurity centre to produce luminescence at room temperatures. To the high energy side of a threshold, which appears to depend on activator concentration, the luminescence efficiency is superlinear above about 15 �0 for KI:Tl (0�0005%).
The Radio Brightness Distribution on the Sun at 21 cm from Combined Eclipse and Pencil?Beam Observations
Authors: Krishnan T , Labrum NR
Published: May 2011

A study of the brightness distribution on the Sun at 21-cm wavelength on April 8, 1959, is described. High resolution observations were made of the partial eclipse on that day with a simple radiometer of high sensitivity. The brightness distribution of the uneclipsed Sun at the same wavelength was obtained using a cross-grating interferometer, which enabled the bright regions to be located accurately.
A High Resolution Galactic Survey at 19·7 Mc/s
Authors: Late CA Shain The , Komesaroff MM , Higgins CS
Published: May 2011

An extensive strip of the Southern Milky Way has been surveyed at 19� 7 Mc/s, using a Mills Cross with a pencil beam 1� 40 wide. The radio contours show a number of dark areas whose positions agree with those of optically-observed H II regions which at this frequency are soon in absorption. In addition, an intensity minimum along the galactic equator appears to represent the effect of absorption due to many H II regions extending to great distances in the galactic plane.
Free Convection in a Vertical Tube with a Linear Wall Temperature Gradient
Authors: Donaldson IG
Published: May 2011

The paper discusses convection in a vertical tube closed at both ends in which the temperature of the walls is arranged to increase linearly with depth. For the purposes of the theory, the convective flow is assumed to be radially symmetrical about the axis of the tube.
Evidence for the Transfer of Corpuscles to Distant Parts of the Sun Following a Solar Radio Burst
Authors: Mullaly RF
Published: May 2011

The brightness distribution of 21-cm radiation over the Sun's surface has been studied for the past four years with the Christiansen crossed-grating interferometer (Christiansen et al. 1961) at Fleurs near Sydney. The observations described here were made using one arm of this cross as a simple grating interferometer, providing a transit instrument with a fan beam of about 2' of arc resolution to half-power points in the east-west direction and very low resolution north-south. The Sun was scanned repeatedly from east to west at time intervals of approximately 4 min.
Errors Due to Diffusion in Drift Velocity Measurements
Authors: Lowke JJ
Published: May 2011

An analysis is made of errors which occur due to diffusion in measurements of the drift velocity of electrons in gases using the methods of Bradbury and Nielsen, Pack and Phelps, and Hornbeck. This analysis includes an account of the influences of back diffusion and the effect of the boundary condition imposed by the receiving electrode. It is shown that, in the case of the method of Bradbury and Nielsen, effects due to diffusion can lead to spuriously high measurements of the drift velocity intro ducing a relative error of the order of 3/h(W/D) (h being the distance between the shutters and WID the ratio of the drift speed to the diffusion coefficient).
Wide?Band Bursts of V.L.F. Radio Noise (Hiss) at Hobart
Authors: Dowden RL
Published: May 2011

Wide-band bursts of radio noise from the upper ionosphere or exosphere have been observed at frequencies from 100 cIs to 250 kc/s. The observed intensity [Wm-2 (C/S)-I] ranges from nearly 10-9 at 100 cIs to 10-19 at 250 kc/s. However, the intensity at the source (above the ionosphere), deduced by subtracting the losses suffered in the ionosphere and below the ionosphere, shows a relatively flat spectrum at a level of the order of 10-10 Wm-2 (C/S)-I.
Statistical Mechanics of Almost One-dimensional Systems
Authors: Barker JA
Published: May 2011

A method is described whereby the classical configuration integral of statistical mechanics can be evaluated with any desired accuracy for almost one� dimensional systems with forces of finite range. The systems contemplated are those in which the molecules or atoms can in any given configuration be ordered serially in such a way that a given molecule may be considered as mteracting only with a definite number of neighbours. This kind of model would be appropriate for example for adsorption of gas molecules in very fine Clipillaries. The results are also of importance in connection ith the " tunnel" model for dense fluids and may have other applications as a basis for approximate treatments of real three�dimell8ional systems.
Heat Transfer and Mass Transfer from the Sphere at Low Reynolds Numbers
Authors: Johnson CHJ
Published: May 2011

Expressions for steady state rates of heat transfer and of mass transfer from a sphere immersed in a parallel flow of fluid consisting of two non.reacting component chemical species are derived. The Reynolds number is much less than unity and free convection is absent. Also, changes in sphere radius are neglected. Heat transfer due to thermal conduction and mass diffusion and mass transfer due to thermal diffusion, as well as transfer by convection, are taken into account. After linearizing the flow equations by supposing changes in flow quantities to be small compared to the flow quantities them� selves expressions for generalized Nusselt and Sherwood numbers are derived.. These expressions show clearly the interactions between the transfer processes, and, in the case of pure heat transfer or pure mass transfer yield, expressions for the usual Nusselt nd Sherwood numbers for a sphere, these expressions having the correct value of unity when the Reynolds number is zero.
Wavenumber Reproducibility of the Radiation 2p10?5d5 of Krypton 86
Authors: Bruce CF , Hill RM
Published: May 2011

The vacuum wavenumber of the radiation 2PlO-5d5 (6056 A) of krypton 86 emitted by a hot cathode Engelhard-type discharge lamp has been established for the temperature range 58-70 oK and current density range 0-1' 0 A/cm'. Wavenumbers relative to the value for the unperturbed state of the radiation have been measured with a reliability of 1 part in 109 using a photoelectric recording and electromechanical scanning FabryPerot interferometer. However, this reproducibility is not possible for different lamps without a more exact specification for the form and operation of the lamp and for the interferometric system used. With the present international specification for the lamp, the reproducibility of this new primary standard of length is better than 1 part in 108.
Simple S and D Deuteron Ground State Wavefunctions Assuming Central and r?2 Tensor Potentials
Authors: Nicholson AF
Published: May 2011

The coupled wave equations for the Sand D parts of the deuteron ground state in the presence of central and tensor forces are shown to reduce to one equation if the tensor potential has an r-2 radial dependence. One wavefunction is then a multiple of the other. It is shown that a simple Hulthen wavefunction may be adjusted to give the observed electric quadrupole moment together with a D-state probability having any desired value between 0�1 and 5�6%.
Bound States and Scattering in an r?2 Potential
Authors: Nicholson AF
Published: May 2011

The bound-state and scattering wavefunctions for a particle moving in a central r-2 potential are investigated. There are no discrete bound states: the discrete states which result when an infinite repulsive core is introduced are specified. The scattering wavefunctions which satisfy physical requirements such as zero net outflow of particles from the scattering region are found. The phase-shifts at are independent of energy and for large I to go to zero as (21+ 1)-1.
On the Relative Position and Origin of Harmonics in the Spectra of Solar Radio Bursts of Spectral Types II And III
Authors: Smerd SF , Wild JP , Sheridan KV
Published: May 2011

Observational results are given concerning the relative positions on the Sun's disk of the fundamental and second-harmonic emissions of solar radio bursts of spectral types II and III. Contrary to simple theory, the results indicate that it is common for the harmonic emission in type II bursts to arrive from directions corresponding to much lower heights in the solar atmosphere than the fundamental. The results for type III bursts are inconclusive but suggest the same trend.
Spread?F and the Perturbations of the Maximum Electron Density of the F Layer
Authors: Singleton DG
Published: May 2011

An analysis has been made of spread-F data obtained from LG.Y. f-plots for several ionosonde stations grouped about longitude 75� W. to establish whether there is any connection between the severity of frequency-spreading (ilJ) and the time of day, season of the year, magnetic activity, height of the F layer, critical frequency of the F layer, and the latitude of the ionosonde station. The diurnal variations of the severity of frequency spreading are found to vary considerably with latitude and season and no clear pattern emerges. Magnetic activity affects the value of ilf but again in a complex way which varies with latitude. The magnitude of ilf seems to be greatest when the layer is high and descending at low and middle latitudes but not at high latitudes. At all latitudes the magnitude of ilf is greatest when the critical frequency is lowest. This is considered to be the dominant effect having a profound influence on the diurnal and seasonal distributions of ilf. These results are discussed in terms of the hypothesis that frequency spreading is due to the availability of a range of values of N IDJ1x. at the maximum of the F2 layer. This range of values is thought to correspond to a system of irregularities each involving an enhancement or a deficiency of electron density relative to the background ionization. The extra ionization involved in the irregularities is estimated to be of the order of 10' electrons/c.c. and is found to vary little with season, magnetic activity, and latitude.
The Relation Between Isophotal Diameters and Redshift of Extra Galactic Nebulae
Authors: Van der Borght R
Published: May 2011

In a recent paper, Sandage (1961) considers the problem of using the angular diameters of extra galactic nebulae in order to decide between various world models. In his approach Sandage uses formulae derived from the field equations, as given by Mattig (1958), under the assumption that both the pressure and cosmological constant are zero.
Singularities in Daily Rainfall
Authors: O'Mahony G
Published: May 2011

Investigations are made of the observed singularities in January daily rainfall means at a number of Australian. stations. Simple graphical methods throw doubts on the random nature of a number of the series, and these doubts are strengthened by results of a significance test involving the parameters of the statistical distribution of daily rainfall. Further work will be necessary to decide whether the observed peaks are due to other than chance, because (i) in the January data the apparent effects were not observed at all the stations studied, and (ii) in a brief survey of some December and. February data the series appeared to be completely random.
On the Use of Lunar Occultations for Investigating the Angular Structure of Radio Sources
Authors: Scheuer PAG
Published: May 2011

It is shown that it is possible, in principle, to recover the strip distribution of brightness aeross a radio source from the Fresnel diffraction pattern which is observed. as a. source is occulted. Practically useful methods of approximating to this ideal 8.1'&. indicated. Rather surprisingly, the resolution attainable in the presence of a given noise level is not related to the angular width of the first Fresnel zone, but is just the same, as it would be if geometrical optics were valid.
Radio Source Interferometry at 1427 Mc/s
Authors: Twiss RQ , Carter AWL , Little AG
Published: May 2011

Interferon18ter measurements at 1427 Me/s of amplitudes and phase angles are tabulated for eight radio sources. The interferometer spacing, orientation, and polarization were all varied.
A Study of Phase Fading of Ionospheric Reflections
Authors: Monro PE
Published: May 2011

Pulsed 2�28 Mc/s radio waves were transmitted imd measurements were made on the first-hop, vertically-incident reflections from the ionosphere. A method of continuously recording the changes of phase difference between the signals at two aerials is described. The general features of the records are described and it is shown that the quasi-periodic type of fading can be explained in terms of two component rays being reflected from two reflecting areas of the ionosphere and interfering at the receiving aerials. The horizontal separation of the two regions is about 50 km in the case analysed. The direction of arrival of the radio waves, the velocity of the amplitude pattern over the ground, and the statistical distribution of the phase difference are also discussed for this type of fading.
Some Effects of Nuclear Explosions on the Ionosphere
Authors: Bowman GG
Published: May 2011

Examination of spread-F conditions at Brisbane and other stations adjacent to the Pacific area, together with an investigation of h'F2 and foF2 changes at the time, suggest that three disturbances propagated from the site of the nuclear explosion at Johnston I. on August 1, 1958. Somewhat similar variations of ionospheric parameters occurred after the explosion on the same site on August 12, 1958. The average speeds of these disturbances were 1666, 647, and 333 m/s.
On Klemens and Lowenthal's Paper on Deviations from Matthiessen's Rule
Authors: Berry RJ , Lovejoy DR
Published: May 2011

In a recent paper on deviations from Matthiessen's rule for platinum Klemens and Lowenthal (1961) classified the deviation patterns, calculated for a number of different platinum resistance thermometers, into three groups, and reported that only one of these groups followed the pattern predicted by Sondheimer and Wilson's (1947) two-band conduction theory. They suggested that if resistors belonging to one particular group (though no matter which group) were selected for use in low temperature platinum resistance thermometry then the resistance-temperature relationship could be expressed accurately by a relatively simple formula. We believe that Klemens and Lowenthal's method of classifying the resistors into groups is open to serious objection and that consequently some of their important conclusions are not necessarily valid.
Proton?Capture Gamma Rays from Nitrogen?13
Authors: Parker AW , Shute GG
Published: May 2011

From a recent experiment in this laboratory (Shute et al. 1962) on the elastic scattering of protons from 12C, resonance levels (E13N, J1t) of 13N were obtained at the laboratory bombarding energies (Ep) shown in Table 1. To confirm these results, an investigation of the yield and angular distribution of gamma rays from the reaction 12C(p'YO)13N and 12C(p'Yl)13N was undertaken. Accordingly, the theoretical angular distributions, W(8), for the gamma ray (Yo) to the ground state of 13Na-) and also for the gamma ray (Yl) to the 1st excited state of 13Na+) were evaluated on the assumptions that overlap of levels in 13N is small and lowest order multipoles are involved. As angular distributions are parity insensitive, these were found to be identical for the two gamma rays expected. The simpler of these angular distributions are also shown on the table. The expected angular distributions indicate that 90� is a suitable angle for yield curves.
Electrical Scanning and Low Pass Filtering in Radio Astronomy
Authors: Bracewell RN
Published: May 2011

In previous studies of aerial smoothing in radio astronomy it has been supposed that the scanning is produced by mechanically moving the aerial. However, the introduetion of a phase gradient across the aperture permits electrical scanning, and the theory of this is an interesting aspect of the general aerial smoothing problem.
Isophotal Contour Maps of Sunspots
Authors: Bray RJ , Loughhead RE
Published: May 2011

Maps are presented showing the complex intensity distribution in the umbrae and penumbrae of two large spots. The umbral isophotes show several points of minimum intensity, in one of which the temperature is some 500 oK below the average for the umbra. This extra-dark region, or "core", is only a few seconds of arc in diameter and is located near one end of the umbra.
Method of Measurement of Electron Energies and Other Data from Spectrograms of V.L.F. Emissions
Authors: Dowden RL
Published: May 2011

It has been shown that the detailed frequency-time shape of discrete very low frequency emissions from the exosphere can be closely fitted on the electron-cyclotron theory by suitably choosing the electron parameters. Additional support for the theory has since been obtained in the verification of its prediction. It is shown here that the fitting process can be reversed so that these parameters can be deduced from the observed spectrograms. These are: the energy and helical pitch of the emitting electrons, the field line which guides them, the instant of their passing through the equatorial plane, and the electron density of the medium. Nomograms are given allowing calculation of these with occasional use of a slide rule and simple arithmetic.
High Temperature Electrical Breakdown in Sodium Chloride
Authors: Hanscomb JR
Published: May 2011

Doubt exists as to the mechanism responsible for electrical breakdown in alkali halide crystals at temperatures where the breakdown strength has generally been found to fall with rise in temperature. As thermal breakdown may be involved, experiments designed to examine this possibility in sodium chloride at 350 �0 have been conducted. It is shown that when linearly rising voltage transients are applied the dependence of breakdown strength on electrical conductivity, time, and energy input is in agreement with the impulse thermal theory for times to breakdown of the order of milliseconds. Conduction of heat is found to be an important factor as the time to breakdown is increased. Effects, such as dendrite growth, which are seen after breakdown with 10-second transients, are also discussed.
Scintillations of Radio Sources and Geomagnetic Activity
Authors: Slee OB
Published: May 2011

The relationship between variations in the Earth's magnetic field and radio source scintillation has been somewhat obscure since the first observation by Little and Maxwell (1952) that, for sources observed through the Northern Auroral Zone, the scintillation rate, but not the amplitude, was closely correlated with the planetary K index. Since then a number of observers, mainly situated in high northern latitudes, also found no relation between the scintillation amplitude and geomagnetic activity. It is the purpose of the present communication to show that at southern temperate latitudes a relationship does exist between these quantities.
Measuring the Linearity of Radio?Astronomy Receivers
Authors: Komesaroff MM , Mathewson DS
Published: May 2011

A convenient practice which is frequently adopted in observational radio 'astronomy is to express all aerial temperatures in terms of the temperature produced by a " point source" of known flux density. A difficulty with this procedure is that, with large telescopes and modern low-noise receivers, the aerial temperatures due to any of the better-known discrete sources are usually comparable with or greater than the receiver noise temperature.
A Study Of The Reaction 12C+12C
Authors: Seaman GG , Quinton AR
Published: May 2011

The reaction 120 +120 has been studied at an incident laboratory energy of 123 MeV. Angular distributions of the emitted oc-particles and protons have been obtained. These angular distributions yielded values of 2�6 �O �3 barnsr and 1�5 �O . 2 barns for the total cross sections for oc-particle and proton production respectively.
On the Existence of an Ionized Layer about the Galactic Plane
Authors: Hoyle F , Ellis GRA
Published: May 2011

The radio frequency spectrum observed in directions towards the galactic pole shows a maximum near 5 Mc/s. It seems unlikely that the synchrotron process responsible for the emission can give such a maximum and it is suggested that the observed fall in the flux density at lower frequencies is caused by absorption in an ionized layer parallel to the galactic plane.
Equilibrium Models of Stars Composed of Pure Helium
Authors: Van der Borght R , Meggitt S
Published: May 2011

Nine equilibrium models of pure helium stars have been calculated for a range of 1 to 17 solar masses. It is shown that for stars larger than two solar masses radiation pressure cannot be neglected. The main effects are a marked reduction in luminosity and a larger core. The change in luminosity does not alter the "main sequence" line in the Hertzsprung�Russell diagram, but shifts the masses down along this line. There is a small decrease in radius accompanied by a corresponding increase in central density.
The Radio Emissions from Jupiter and the Density of Jovian Exosphere
Authors: Ellis GRA
Published: May 2011

The properties of cyclotron radiation from bunches of electrons trapped in a Jovian exosphere are discussed. It is shown that, if the polar magnetic field intensity is 15 gauss and the magnetic axis is inclined 10� to the rotation axis, the calculated properties agree with those observed for the decametric radiation providing Jupiter is surrounded by an extensive exosphere. The electron density of the exosphere varies mainly as the magnetic field intensity and at l'5Rj is equal to 103/cm3.
On the Accuracy of the Tan hl Distorted Wave Approximation for Scattering Phase-Shifts
Authors: Swan P
Published: May 2011

The distorted wave approximation for tan ?l involves a wave function distorted from its asymptotic form at r � 8 by a form factor g1(r). Schwinger's variational principle is adapted to show that increasing the number of variable parameters in g1(r) does not necessarily improve the firs
The Thermal Expansion of an Almost Linear Chain
Authors: Lloyd P , O'Dwyer JJ
Published: May 2011

A linear chain model of a close-packed line of atoms in a solid has been constructed. The model differs from usual linear chain models in that the chain is not strictly one-dimensional, the individual atoms being free to move in three dimensions. To account for the interaction of the chain with its surroundings an effective potential has been introduced. When the thermal expansion of solid argon is calculated, satisfactory agreement with experiment is obtained in the classical region.
The Reflection Coefficient of the Night-time Ionospheric F Region
Authors: McGilvray JP
Published: May 2011

Night-time records of Fa reflections at normal incidence have been made at three frequencies, 2�28, 3�84, and 5�8 Mcls, using a swept-gain technique. The reflection coefficient of the F region has been measured from these records. The reflection coefficient is appreciably lees than unity at all frequencies for a large part of the recording period. Resolved trace measurements show the absorption to occur in the deviative region. There is some suggestion of the reflection coefficient, measured at 2�28 and 3; 84 Mcls, depending on season, monthly K" sum, and true height of reflection. The reflection coefficient measured at 5�8 Mcls appears to be independent of these parameters. There is 8 suggestion that the reflection coefficient is related directly to i.E, for K indices=5, and inversely to the operating frequency.
Correction to the Paper "Precision in a Scanning Interferometer"
Authors: Hill RM , Bruce CF
Published: May 2011

It has been brought to the authors' attention (Hanes, personal communication) that the results obtained for the limiting precision in a scanning optical interferometer (Hill and Bruce 1U62) are invalid for the particular conditions examined. Although there does exist a photon noise distinct from the shot noise in the photodetector its effect is very small. The transmittance of the Fabry-Perot interferometer was incorrectly evaluated and when allowance is made for this the limiting precisions of the Michelson and Fabry-Perot interferometers are about equal.
A Quantum Mechanical Correction to the Statistics of the Almost One-dimensional Chain
Authors: Lloyd P , O'Dwyer JJ
Published: May 2011

A series expansion in powers of Planck's constant is adapted to yield the quantum mechanical correction to the classical statistics of an "almost one�dimensional" system. The result is of validity at the high temperature end only of the specifically quantum temperature region. Application to the thermal expansion of solid argon gives reasonable agreement with experiment.
The Design and Characteristics of Highly Ionized Hydrogenous Laboratory Plasma Sources
Authors: Brennan MH , Lehane JA , Millar DD , Watson-Munro CN
Published: May 2011

The design and construction of two highly ionized hydrogenous plasma sources are described. Details are also given of the measurements that have been made to investigate the formation, density distribution, and decay of plasmas.
Damped Waves Associated with Thermal Convection
Authors: Bosworth RCL , Groden CM , Wecksler OS
Published: May 2011

Damped temperature-time oscillations associated with thermal convection are analysed and the energy of thermal inductance is identified with the free energy of entropy flow from the convection chimney.
Observations of Radio Emission from Normal Galaxies
Authors: Mathewson DS , Rome JM
Published: May 2011

The results of observations of 37 normal galaxies using the 21O-ft steerable reflector of the A.N.R.A.O. at 1410 and 408 Mcls are presented. All southern galaxies brighter than tenth magnitude were studied. Twenty galaxies were detected, fourteen of which were new identifIcationis. Sc galaxies were found to have a mean radio index at 1410 Mcls of +3�3 with an r.m.s. deviation of 0�6. The ratio of optical to radio emission was signifIcantly higher for irregular and early type galaxies than for Sb and Sc galaxies_ Contrary to general belief, no constant relationship was found between the optical and radio sizes of spiral galaxies. Two discrete radio sources were detected in the Pegasus I cluster, one of which may be identified with the El galaxy, NGC 7626. The radio source found in Pegasus II coincided in position with the E3 galaxy, NGC 7501, in the cluster.
Massive Stars with Uniform Composition
Authors: Van der Borght R , Meggitt S
Published: May 2011

It is the purpose of the present paper to derive a set of tables which greatly facilitate the construction of models of massive stars with uniform composition, to show how these tables can be used and finally to apply the method to derive models of stars composed of pure hydrogen in which a small amount of 12C is present.
Electron Energy Loss at Collision in Current-maintained Plasmas
Authors: Somerville JM
Published: May 2011

In an important class of laboratory plasmas, the plasma is maintained in existence by the passage of a steady direct current through it. Energy taken from the electric field which drives the current maintains the ionization in the plasma against losses of charged particles by diffusion or recombination. This energy is initially supplied chiefly to the electrons, which can drift rapidly in the field, and the majority of it is ultimately transferred to the heavy plasma particles by means of electron-heavy-particle interactions. In the steady state the energy input to the plasma from the field is balanced by the energy lost from the plasma by various means, including radiation, thermal conduction and the diffusive transport of ionization, excitation, and dissociation energy. Such current-maintained plasmas may exist under a very wide range of conditions with variations of the order of ten decades each in pressure, current density, and ionization density.
The Refractive Index of Methyl Chloride at 10 Gc/s
Authors: Burton CH , Lasich WB , Noon JH , Parsons RW
Published: May 2011

The dielectric behaviour of gases in an electromagnetic field has been studied theoretically by Van Vleck and Weisskopf (1945). They found expressions for the contributions to the absorption coefficient a and the refractive index n at a frequency v arising from transitions between quantum states j and i. If v is much less than the natural frequency Vii associated with the transition, and if the line width is also small compared with Vii' their results give:
The Drift Velocities of Free and Attached Electrons in Water Vapour
Authors: Lowke JJ , Rees JA
Published: May 2011

The drift velocities of free and attached electrons in water vapour have been determined as functions of the parameter E/p at a temperature of 293�K. The results are compared with those of other workers and With theoretical predictions. Measurements of the drift velocity of free electrons in mixtures of hydrogen and water vapour are also presented.
The Damping of a Fluctuating Concentration by Continuous Sampling Through a Tube
Authors: Philip JR
Published: May 2011

Concentrations in turbulent fields may be measured by sampling through a tube leading to a continuous analyser. This technique has important applications in geophysics and chemical engineering.
The Influence of a Charge on a Charged Particle Flux
Authors: Telford J
Published: May 2011

The variations in intensity of a charged particle flux when observed from a position adjacent to a point charge have been calculated. This was done to estimate the effect of a Coulomb field on charged particles in space. It is shown that for repulsion a region of complete shadow occurs which has a width, at a particular radius, dependent on the particle energy, the radial distance, and the magnitude of the scattering charge
Determination of Diffusion Coefficients from Observations on Grenade Glow Clouds
Authors: Johnson ER , Lloyd KH
Published: May 2011

Glows have been observed at Woomera when grenades ejected from Skylark rockets have been detonated in the altitude range 90-170 km. Using results obtained from these glows by a special scanning photometer located on the ground, an estimate has been made of the diffusion coefficient in the region 120-160 km. The theoretical model which is used to describe the behaviour of the explosion products incorporates the assumptions of molecular diffusion, a Gaussian distribution of particle density, and an optically thin cloud. The effects of consumption of the cloud particles are included in the model.
General Characteristics of pc-type Pulsations
Authors: McNicol RWE , Mainstone JS
Published: May 2011

An analysis of geomagnetic micropulsations of the pc type, i.e. continuous pulsations detectable for several hours at a time, recorded at Brisbane (35�S. geomagnetic latitude) from May to October 1962 has shown that the frequency spectrum was usually spread over several octaves even when the waveform shown on the chart records was quasi-sinusoidal. The greatest spread was around midday, being from about O� 02 to O� 08 c/s on days of mild magnetic activity (Kp = 3). Generally pc occurred most strongly between about 0600 and 2000 L.M.T., but on occasions were recorded throughout the whole 24 hours. A striking feature was the sudden change in activity which frequently took place within an interval of a few minutes. Good correlation was obtained between both the amplitude and the highest frequency in the pc spectrum, and Kp
Distribution of Auroras in the Southern Hemisphere. III. Comparison with Northern Hemisphere
Authors: Bond FR , Jacka F
Published: May 2011

While the distribution of auroras in the southern hemisphere is well represented n terms of each of the parameters 81, 82, and 83 (introduced in Part II), the northern emispheres distribution is not satisfactorily represented in terms of 81. In terms of 2 or 83, and within the limits of accuracy of the data, the distributions in the two hemispheres are conjugate. To carry this investigation further, much more accurate data and more refined concepts are required.
A Low Resolution Hydrogen-line Survey of the Magellanic System. I. Observations and Digital Reduction Procedures
Authors: Hindman JV , McGee RX , Carter AWL , Holmes ECJ , Beard M
Published: May 2011

A survey of neutral hydrogen in the Clouds of Magellan has been made using a digital recording system in conjunction with a multichannel receiver and a 21 ft aerial. The system has been developed for use with the 210 ft radio telescope of the Australian National Radio Astronomy Observatory at Parkes, N.S.W.
Effect of Magnetic Anomalies on Very Low Frequency Discrete Emissions
Authors: Dowden RL
Published: May 2011

The author has suggested (Dowden 1962) that. the spectrogram (frequency v. time) shapes of V.L.F. discrete emissions can be explained as Doppler-shifted cyclotron radiation from electrons spiralling along a geomagnetic field line away from the observer. The emission frequency is given by Eidman (1958),
Thermal Properties of Systems Exhibiting Optimum Countercurrent Heat Exchange
Authors: Bosworth RCL , Groden CM
Published: May 2011

Heat flow in heat exchange systems, operating at constant pressure, is.considered in relation to the thermodynamical measure of entropy called by Keenan. the availability. The ratio of the maximum attainable mechanical work from two.systems (1) and (2) is shown to be equal to the ratio of the two availabilities or.l:1B1/l:1Bg, and this reasonably approaches unity only when the exchanger involves.countercurrent flow. The temperatures and temperature differences may be plotted against the linear dimension along the exchanger. The temperature difference will pass through one or more stationary values associated with a temperature T*. At such a pivotal point, we may define enthalpies, l:1H;, l:1H; and specific heats (c;, c;) of the two streams in which the following relations hold:
Luni-solar Variations in the Ionosphere
Authors: Duncan RA
Published: May 2011

Neutron-gamma-ray coincidence measurements have been made in the reaction 19F(d,ny),oNe at bombarding energies between 500 and 700 keV. Time offlight determination of neutron energy indicates a new energy level in .oNe at lO� 31 �O' 07 MeV. From angular distributions of the neutrons, and observation of the gamma� decay spectrum of the MeV state, spin and parity of 1 + are inferred for this state.