bluuebunny/crossref_metadata_2025 huggingface dataset:
A Relation Between Snow Cover, Cirrus Cloud, and Freezing Nuclei in the Atmosphere
Authors: Bowen EG
Published: May 2011

It is reasonable to suppose that observations like that of cirrus cloud in the upper air and heavy falls of snow in relatively warm latitudes correspond to the presence of a large number of freezing nuclei in the atmosphere. A 300-year record of snow covering the ground at Tokyo and a 10-year record of cirrus cloud in Western Australia are examined and compared with one year's measurement of freezing nucleus concentration. The curves show a high degree of correlation, and all three tend to maximize on certain calendar dates.
January Freezing Nucleus Measurements
Authors: Bowen EG
Published: May 2011

Measurements of the concentration of freezing nuclei in the atmosphere have been made in widely separated parts of the globe during January in one or more of the three successive years 1954, 1955, and 1956. The results of all three sets of observations are summarized and it is shown that high freezing nucleus counts tend to occur on dates which are identical or nearly identical with those on which unusually heavy falls of rain have previously been shown to occur. The results are discussed in relation to the possible connexion between meteoritic dust and world rainfall.
Counts of Atmospheric Freezing Nuclei at Pretoria, January 1956
Authors: Mossop SC , Carte AE , Heffernan KJ
Published: May 2011

An account is given of freezing nucleus measurements made in aircraft at Pretoria, South Africa, during the month of January 1956. The measurements showed variations from day to day, which are discussed in relation to the prevailing weather situation. The possible connexion with particles from meteor showers is touched upon.
Counts of Atmospheric Freezing Nuclei at Palo Alto, California, January 1956
Authors: Bracewell RN
Published: May 2011

Measurements of freezing nucleus concentration were made at Palo Alto, California, each day during January 1956. They show maxima on two out of the three dates anticipated from the meteor theory.
Double?Layer Phenomena in the Es Region
Authors: Thomas JA
Published: May 2011

At Brisbane, ionospheric records are frequently made which show the simultaneous presence of two types of Es ionization, one at greater virtual range than the other; these have been classified by McNicol and Gipps (1951) as "sequential" type (Ess), and "constant-height" type (Esc), respectively. Such records occur most frequently in the late afternoon and early evening, particularly in summer, when Ess is in its last stages and Esc is building up to its maximum intensity (Thomas 1956).
Application of Mathematical Theories of Approximation to Aerial Smoothing in Radio Astronomy
Authors: Arsac J
Published: May 2011

An aerial rarely provides a perfect image of a radio brightness distribution. If we consider an array as a filter of "spatial harmonics", the image function is a trigonometric sum approximating the object function. An application of mathematical theories shows the influence of the length and the shape of the array on the difference between object and image. Whatever the array, the image contrasts are bounded. The results provided by various arrays of the same length may be reduced by linear transforms. Inaccuracies of measurement, especially those due to the receiver noise, add to the systematic error due to the finite length of the antenna. We may try to get a compromise between these various causes of uncertainty.
A Preliminary Survey of Radio Sources in a Limited Region of the Sky at a Wavelength of 3·5 m
Authors: Mills BY , Slee OB
Published: May 2011

A preliminary catalogue has been prepared of radio sources observed in a sample area of about one steradian near the celestial equator: a total of 383 sources is listed. The brightest nebulae in the area are found to be radio sources. Statistical analysis of the catalogue reveals no obvious cosmological effects except, perhaps, for a significant degree of clustering which may be indicative of metagalactic structure. The catalogue is compared in detail with a recent Cambridge catalogue which includes the sample area; it is found that they are almost completely discordant. A theory is developed which explains this discordance in terms of instrumental effects and it is concluded that a major part of the Cambridge catalogue is affected by the low resolution of their radio interferometer.
Protons Ejected from Nickel by 17·5 MeV Bremsstrahlung
Authors: Spicer BM , Muirhead EG , Shute GG
Published: May 2011

It has been shown that the energy and angular distribution of photoprotons from middle-weight nuclei (Z about 30) can be almost entirely accounted for by the statistical theory of nuclear reactions (Byerly and Stephens 1951; Toms and Stephens 1954). The evidence indicates that the direct photo effect contributes only a small amount to the emitted photoproton spectrum. However, the statistical theory does not explain, among other things, why the photoproton yield at 23 MeV from copper and nickel should be about three times that from cobalt (Mann and Halpern 1951).
The Mean Thickness of Night-time Es Clouds at Brisbane
Authors: Hosking RH
Published: May 2011

It has been stated that the sporadic E region of the ionosphere at Brisbane is very thin, with a maximum thickness of the order of a few hundred metres (McNicol and Gipps 1951). The measurements reported below indicate that at Brisbane Esc clouds (patches of enhanced ionization in the sporadic E region which maintain an almost constant height) at night are, on the average, almost certainly less than 1 km thick.
A Method of Heating Matter of Low Density to Temperatures in the Range 105 to 106 °K
Authors: Knox FB
Published: May 2011

If gas of controlled composition could be held steadily at temperatures greatly exceeding 104 �K an interesting field for experimental research would be open. In particular it should be possible to duplicate some conditions existing in stellar atmospheres. Current research into the feasibility of constructing fusion reactors adds further interest (Thirring 1955).
Free Path Formulae for the Electronic Conductivity of a Weakly Ionized Gas in the Presence of a Uniform and Constant Magnetic Field and a Sinusoidal Electric Field
Authors: Huxley LGH
Published: May 2011

A general free path formula is given for the drift velocity of electrons in a weakly ionized gas in a sinusoidal electric field. Most special cases of interest, including the magnetic deflection of an electron stream in a gas, are readily derivable from the general formula.
Meteor Activity in the Southern Hemisphere
Authors: Weiss AA
Published: May 2011

Activities and radiants of meteor showers detected by radio equipments at Adelaide from 1952 to 1956 are summarized. A composite picture of shower and sporadic meteor activity is compared with a similar picture compiled from northern hemisphere radio counts. The distribution of the radiants of the more important showers reveals a pronounced concentration to the ecliptic, with a component extending to high latitudes.
Observation of a New Type of Flare
Authors: Bray RJ , Loughhead RE , Burges VR , K McCabe Marie
Published: May 2011

The importance of chromospheric flares from both the astrophysical and geophysical points of view is now generally recognized, but, in spite of the extensive observational material collected by Ellison, Dodson, and others, it must be admitted that the mechanism of their origin is still little understood. In this paper we present observations of a hitherto unobserved phenomenon, namely, the ejection of a mass of very bright material from a flare some 28� from the limb of the Sun. The ejection occurred several minutes before flare maximum. It was approximately 10,000 by 30,000 km in size and moved outwards with a velocity across the line-of-sight of 300 km/sec. As it did so, it brightened appreciably, reaching maximum intensity 3� min after expulsion, its height then being 25,000 km. The ejection was quite unlike the dark surge prominences often emitted from flares, and in fact, except for its motion, possessed all the properties of a small flare.
The Cross Section for the 16O(g,n)15O Reaction
Authors: Spicer BM
Published: May 2011

There have been a number of attempts to account for the nature of the giant resonance of nuclear photodisintegration (e.g. Goldhaber and Teller 1948; Steinwedel and Jensen 1950; Wilkinson 1955; and others). Levinger and Bethe (1950) believe that a " many-level" theory of the giant resonance is more satisfactory than a single-level theory. The existence of fine structure in the yield curve of the 16O(?,11,) reaction at energies near the giant resonance (Penfold and Spicer 1955) supports this conclusion. The purpose of the present note is to show that the existence of structure within the giant resonance may be demonstrated more simply than by the tedious study of fine structure in yield curves.
Counts of Extragalactic Radio Sources and Uniform Model Universes
Authors: McVittie GC
Published: May 2011

The radio sources are assumed to be galaxies sharing in the red-shift phenomenon. The counts of such sources to successive limits of flux density are interpreted in terms of the model universes of general relativity. The flux density in each infinitesimal interval of frequency is assumed to be proportional to a power of the frequency and to a multiplicative parameter, both these quantities being regarded as functions of the red-shift, i.e. of the time of travel of the radiation. All sources at the same distance from the observer are assumed to be identical radiators; this permits the introduction of a standard comparison source. The data in the Sydney catalogue can then be interpreted in terms of radio sources of constant strength�(i.e. which are independent of the red-shift) if they are similar to NGC 1275, taken as standard. If they are similar to Cygnus A, the data imply that the sources were radiating more strongly when their radiation left them than is Cygnus A now. This type of conclusion appears to be unavoidable for the data of the Cambridge catalogue. It is briefly explained how to modify the theory to take account of a variation with time of the space-density of sources and also of a mixture of comparison sources.
The Solar Daily Variation of Cosmic Ray Meson Intensity at l = 52 °S. and l = 73 °S.
Authors: Parsons NR
Published: May 2011

Some preliminary results are given of an investigation of solar daily variations recorded by vertically directed meson telescopes at Hobart, Tasmania (geomagnetic latitude (? = 73 �S.) and at Mawson, Antarctica (? = 73 �S.). Long-term trends in phase of the variation are found to be similar to those reported by observers in the northern hemisphere. However, a substantial and fairly consistent phase difference in local time is apparent between the two stations, and its origin is discussed. A brief discussion of pressure-correction procedures is also given.
The Incidence of Meteor Particles Upon the Earth
Authors: Weiss AA
Published: May 2011

Radio echo rates for both shower and sporadic meteors, measured at Adelaide with the 27 Mcls C.W. equipment, are applied to the calculation of the incident flux of meteors above limiting brightnesses in the range MR < + 7�5. On the hypothesis of a strongly velocity-dependent ionizing probability, reached after a critical evaluation of the observational material, the meteor flux above prescribed limiting meteor particle masses, and the space densities of meteor particles, are also calculated. These fluxes and densities agree reasonably well with independent evaluations from visual meteor rates. The amount of meteoric matter falling on the whole Earth per day within particle mass limits 10?1 to 10?4 g, for sporadic meteors and some showers, is also estimated.
The Resolution of the Clock Paradox
Authors: Dingle H
Published: May 2011

In a recent paper (Builder 1957) Dr. G. Builder discusses the well-known "clock paradox" on the basis of the restricted theory of relativity. The problem considered, to quote his own description, arises from the following hypothetical experiment: "It is supposed that two observers R and M, equipped with identical synchronized clocks, are initially at rest together, e.g. at the origin of an inertial reference system S. The observer M is sent on a journey along the x-axis of S, travelling away from R with uniform speed v for a time T, coming to rest for a time t, and then returning with the same speed v to rejoin R after a total time 2T + t as read on R's clock. It will, in the first instance, be supposed that the times required to accelerate, or decelerate, M are so small that they can be neglected without appreciable error."
The Clock?Retardation Problem
Authors: Builder G
Published: May 2011

In his paper above (Dingle 1957) Professor Dingle attempts to show that my treatment of the problem of relative clock retardations (Builder 1957) is completely incorrect and, that such retardations cannot occur.
A New Absolute Method of Hygrometry. II. The Properties of Potassium Chloride Crystal Elements
Authors: Wylie RG
Published: May 2011

A new type of hygrometer, which has been termed the electrolytic condensation hygrometer, was described in the first of the present two papers. Its capabilities and limitations depend mainly on the characteristics of the conducting liquid layer formed on the surface of the crystal element used ; these characteristics depend in turn on those of the surface of the crystal.
Directional Measurements of the Daily Variation of Cosmic Ray Meson Intensity at l=73 °S.
Authors: Parsons NR
Published: May 2011

Measurements are reported of the daily variations of meson intensity at Mawson, Antarctica (?=73 �S.), recorded by counter telescopes inclined at 45� to the vertical in each of north, east, south, and west directions. The results, together with those from a vertical telescope, are examined and found to be inconsistent with an assumed common origin of the different directional variations in the interaction of an anisotropic primary radiation with the Earth's dipole field.
The Distribution of Radio Brightness Over the Solar Disk at a Wavelength of 21 Centimetres. IV. The Slowly Varying Component
Authors: Christiansen WN , Warburton JA , Davies RD
Published: May 2011

A large number of highly emitting regions on the Sun have been studied individually by means of a 32-element interferometer which produces fringes 3 min of arc wide at a wavelength of 21 cm. These regions are responsible for the slowly varying component of the solar radiation at decimetre wavelengths.
The Crab Nebula and the Origin of Interstellar Magnetic Fields
Authors: Piddington JH
Published: May 2011

Electromagnetic effects in the Crab nebula have been investigated with the following conclusions: (1) No appreciable proportion of the present central magnetic field could have passed in or out through the surrounding ionized supernova shell during its 900 years life.
A Method of Heating Matter of Low Density to Temperatures in the Range 105 to 106 °K
Authors: Knox FB
Published: May 2011

A method of confining fully ionized gases entirely by means of an oscillating electro-magnetic field is described. The gas is heated by eddy currents induced in it by the oscillating field.
The Boundary Conditions Governing Fluid Motions in Porous Media
Authors: Philip JR
Published: May 2011

Further work has shown that the second of conditions (2.4) of a recent paper (Philip 1957?), supposed to govern the potential distribution during fluid motion in a porous medium, holds only for the case of linear axial flow in tubes of general cross section. The stated condition implied that the equipotential surfaces intersected the fluid-solid interface (a stream surface) normally. This may be approximately true for all media, but it can be shown by reference to the "complete" Stokes-Navier equation ((1.9) of Philip 1957) to be not exact in general. It follows that equation (2.8) and the thermal analogy (Section III) presented in that paper hold exactly for axial flow in tubes of general cross section, but are merely approximations when applied to more general media. Exact analysis for the general medium promises to be complicated and will not be pursued here.
The Theoretical Evaluation of the Townsend Coefficient a/p For Hydrogen
Authors: Blevin HA , Haydon SC
Published: May 2011

The theoretical evaluation of the first Townsend ionization coefficient x/p (ionizations cm-1 (mm Hg)-l) requires a knowledge of the precise form of the velocity distribution of electrons in the gas. This distribution was determined theoretically by Morse, Allis, and Lamar (1935) for the particular case when only elastic collisions take place in the gas, but its form is not known for the more complex situation when inelastic collision processes also occur.
Electromagnetic Propagation in an Almost Homogeneous Medium
Authors: Bolie VW
Published: May 2011

This paper concerns the development from Maxwell's electromagnetic equations of an equation of propagation in an almost homogeneous medium. The equation is applied to the problem of determining the secondary wave produced by an isolated Gaussian-shaped perturbation in the refractive index. An exact solution is obtained for points located on the axis of symmetry parallel to the direction of propagation of the incident primary wave.
The Distribution of Flare Heights as Derived from Limb Flares
Authors: Giovanelli RG , K McCabe Marie
Published: May 2011

In recent papers, J. W. Warwick (1955) and Constance S. Warwick (1955) have discussed the heights of flares-the former by examining the distribution of apparent areas across the disk, and the latter by measuring heights of limb flares.
The Ionization of Liquid Argon by a-Particles
Authors: Stacey FD
Published: May 2011

Calculations suggest that in liquid argon the column of ionization produced by :an a-particle consists of a core of positive charge 0�6?1 �5�10?5 cm in diameter concentric with a larger cloud of electrons extending to a diameter of 40�10?5 cm. This leads to a new description of charge separation in an applied electric field, in which the positive and negative charges are drawn apart slightly (polarized) and the more energetic electrons Bscape from the edge of the column.
The Wilson Effect in Sunspots
Authors: Loughhead RE , Bray RJ
Published: May 2011

New observations of the Wilson effect in a small regular sunspot have demonstrated the reality of the phenomenon. The measurements are based on 38 photographs selected from some 24,000 obtained during the passage of the spot from the east to the west limb.
On the Galvanomagnetic, Thermomagnetic, and Thermoeleotric Effects in Isotropic Metals and Semiconduotors
Authors: Moore EJ
Published: May 2011

The calculation of the galvanomagnetic, thermomagnetic, and thermoelectric effects in those isotropic metals and semiconductors which can be represented by the two-band model is simplified and extended to cases not previously treated. General expressions are obtained for effects involving time-independent electric fields, magnetic fields, and thermal gradients. Analytic formulae are given for the isothermal galvanomagnetic effects when a high frequency electric field is applied together with a time-independent magnetic field.
Photoneutrons from Natural Magnesium
Authors: Spicer BM , Allum FR , Baglin JEE , Thies HH
Published: May 2011

Recent experiments on photoneutron production from natural magnesium have produced contradictory results. Katz et al. (1954) have used brems-strahlung from a 22 MeV betatron to irradiate a natural magnesium target. The emitted neutrons were detected with boron trifluoride (BF3) counters placed in a paraffin block.
A Suggested Improvement to the C.W. Technique for Measurement of Meteor Velocities
Authors: Mainstone JS , Elford WG , Weiss AA
Published: May 2011

Radio methods of measuring meteor velocities, whether by pulse (Davies and Ellyett 1949) or C.W. techniques (Mckinley 1951), ultimately depend on a knowledge of the separation, along Cornu's spiral, between points representing any two maxima or any two minima of the echo waveform. The relation , where R0 is the minimum range of the echo and ? is the wavelength, enables these" zone values " to be correlated with line segments s of the meteor trail.
The Giant Resonance of Photodisintegration of Tantalum
Authors: Spicer BM , Thies HH , Baglin JE , Allum FR
Published: May 2011

The neutron yield from tantalum, has been measured as a. function of bremsstrahlung energy, and from this the shape of the cross section for the nuclear absorption of photons by tantalum has been deduced. This cross section shows definite evidence that it is made up of two component parts. The result is in agreement with the theoretical predictions of Danos (1958) for this nucleus, both regarding the existence of the two components and the energy separation of the two peaks. Using the Danos theory, the intrinsic electric quadrupole moment for tantalum, is calculated to be 6�1 barns�10 per cent.
The Fluctuating Field Ferromagnet at Low Temperatures
Authors: Stacey FD
Published: May 2011

Neel's concept of fluctuating intermolecular field may be ascribed to localized but migratory elementary magnets in ferromagnetics with non-integral Bohr magneton numbers. This concept allows a low temperature ordering of elementary magnets and a variation with temperature of the effective number of nearest neighbours between which exchange interactions occur. This model alone cannot explain the approach to absolute saturation at 0 �K of a ferromagnetic, but it modifies the constant of the T3/2 law of approach. In the case of ordering by the mutual attraction of parallel elementary magnets, each consisting of a coupled pair of spins (s = 1) the theoretical and experimental values of this constant for nickel are reconciled.
Solar Brightness Distribution at a Wavelength of 60 Centimetres. II. Localized Radio Bright Regions
Authors: Swarup G , Parthasarathy R
Published: May 2011

The localized radio bright regions on the Sun which give rise to a slowly varying component of the solar radiation were studied at a wavelength of 60 cm, using a 32-aerial interferometer with a beamwidth of 8�7 min of arc. The observations were undertaken during July 1954 to March 1955 and were limited in number due to this being a minimum period of the solar cycle. The low activity, however, provided the advantage of simple interpretation as often only one region was present on the solar disk.
Optical Observations of the Solar Disturbances Causing Type II Radio Bursts
Authors: Giovanelli RG , Roberts JA
Published: May 2011

Identifications have been established for the solar optical events associated with a number of type II radio bursts. Near or at the limb these have been ejections with velocities exceeding that of sound in the corona. Where the event has been on the disk there has usually been a very bright flare, with some evidence of dark filament activity. In two cases the event was the disappearance (i.e. ejection) of a filament with the subsequent development of flares on either side.
Ferromagnetic Exchange Between Coupled Pairs of Electrons
Authors: Stacey FD
Published: May 2011

Incomplete shells of 3d electrons in the first transition series of elements are responsible for the ferromagnetism of these elements, but the parallel coupling of the spins of these electrons remains an assumption in the theory of ferromagnetism. It is required that exchange interaction between the 3d electrons of neighbouring atoms should be positive (the sign causing parallel alignment of spins). Mathematically, treatment of ferromagnetic exchange is similar to that of the homopolar chemical bond, in which it is clear that exchange interaction is negative, giving a lower energy for antiparallel spins than for parallel spins. Mathematical difficulties have prevented any adequate demonstration that the reverse is the case in ferromagnetism.
Freezing Nucleus Measurements in January 1957
Authors: Bowen EG
Published: May 2011

It is well known that the appearance of the ice phase in supercooled clouds is one of the more important phenomena leading to the formation of rain. The formation of ice crystals is itself dependent on the freezing nucleus content of the atmosphere. Little is known about the nature and origin of natural freezing nuclei, but daily measurements of freezing nucleus concentration made in different parts of the world during the month of January in the three years 1954, 1955, and 1956 have suggested that some fraction of them might be of extraterrestrial origin (Bowen 1956). The present note describes a further series of measurements made during January 1957.
Observations of Changes in the Photospheric Granules
Authors: Bray RJ , Loughhead RE
Published: May 2011

Using a sequence of 29 good-quality photographs extending over a period of 10 min, an attempt is made to detect changes in the brightness, size, and shape of individual granules. Of the 125 granules for which there is sufficient data, 57 per cent. show no detectable change during their observed periods of persistence, an additional 14 per cent. showing only minor changes of shape. Although there is some tendency among granules showing change for size increases to predominate over decreases, brightness increases and decreases occur with equal frequency. There is no correlation between the two types of change, nor is there any tendency for brightness or size variations to occur during any particular part of the life cycle. Observations with higher resolving power are required to elucidate the changes occurring during the formation and dissolution�of individual granules.
The Radio Emission from Centaurus?A and Fornax?A
Authors: Shain CA
Published: May 2011

Observations of the sources Centaurus-A and Fornax-A at 19�7 Mcls, with a P��4 aerial beam, have been compared with observations at higher frequencies, in particular with Sheridan's 85�5 Mcls observations. There are marked similarities between the sources, in their general appearances, linear dimensions, spectra, and powers radiated at radio frequencies.
Variations in Ionospheric F-Region Characteristics
Authors: Brice NM
Published: May 2011

It is well known that F-region characteristics in the undisturbed ionosphere change with season and with sunspot activity and that these effects are greatest at high geomagnetic latitudes (Maeda 1955; Martyn 1955).
The Effect of Sudden Ionospheric Disturbances (S.I.D.'s) on 2·28 Mc/s Pulse Reflections from the Lower Ionosphere
Authors: Gardner FF
Published: May 2011

The effects of sudden ionospheric disturbances (S.LD.'s) on the complicated structure ()f ionospheric echoes obtained with moderately high sensitivity at 2�28 Mcls are described. The observations indicate that flares of classes 2 and 3 can produce high values of electron density near the base of the ionosphere. Mean electron density can exceed 1000/cm3 over the height range 60-75 km, where the greatest relative increase in ionization occurs. Nevertheless, the greater part of the S.LD. absorption of waves reflected from the E region or above still occurs above 85 km.
Elevation, Height, and Electron Density of Echoing Points of Meteor Trails
Authors: Weiss AA
Published: May 2011

Continuous and systematic operation of a C.W. equipment which measures simultaneously several characteristics of meteor echoes, including the location in space of the reflection point, provides the basic material for an examination of the geometry of detection of meteor trails by radio equipments and of the processes underlying selection of echoes for measurements of different kinds.
The Detection of Time-correlated Photons by a Coincidence Counter
Authors: Twiss RQ , Little AG
Published: May 2011

The existence of a correlation between the arrival times of photons has been confirmed by measurements with a coincidence counter having a resolving time of 3�5 X 10-9 sec in three different experiments. In the first experiment it was found that the number of coincidence counts recorded from two photomultipliers, the apertures of which were optically superimposed, was significantly greater than when the light beams were incoherent. Furthermore, the number of these correlated counts was in satisfactory agreement with that predicted by theory. In the second experiment the change in the number of excess coincidences was measured as the degree of coherence of the light was altered by increasing the apparent separation of the photocathodes, and in this case also there was reasonable agreement between theory and experiment. In the final experiment it was shown that there was a significant difference between the number of coincidences observed when the light beams were in identical as opposed to orthogonal polarizations, and this last result especially makes it extremely improbable that the correlation could be caused by some spurious effect, such as plasma oscillations in the source, since the light source itself was found to be completely unpolarized.
Irregular Coulomb Wave Functions
Authors: Learner A , Robson BA
Published: May 2011

In a recent paper (Learner and Robson 1958), henceforth referred to as I, a skeleton table of values of the regular Ooulomb wave functions was given in the integral representation.
The Energy Spectrum of Protons From the 7Be(d,p)8Be Reaction
Authors: Spear RH
Published: May 2011

The experimental evidence relating to the low-lying excited states of 8Be has been discussed in a previous paper (Spear 1958). This note presents the results of a preliminary study of the energy spectrum of protons from the previously unreported 7Re(d,p)8Be reaction, undertaken with a view to obtaining further information on the problem.
The 58Ni(n,p)58Co, 58Ni(n,2n)57Ni, and 58Ni(n,np)57Co Cross Sections at 14·1 MeV
Authors: Purser KH , Titterton EW
Published: May 2011

The energy spectrum of the protons which are emitted when nickel is bombarded with 14 �1 MeV neutrons has been studied recently by several workers-Allan (1957), Colli, Facchini, et al. (1958), and Colli, Pignanelli, et al. (1958). The results of these experiments do not allow an accurate estimate of the relative importance of contributions from the (n,p) reaction and the (n,np) reaction. Such information is necessary when any reaction mechanism is postulated to account for the experimental results. In these experiments, therefore, activation techniques have been used to measure these two cross sections separately for the isotope 58Ni at 14�1 MeV; in addition, the 68Ni(n,2n)57Ni cross section has been remeasured.
Deviation from Matthiessen's Rule and Lattice Thermal Conductivity of Alloys
Authors: Klemens PG
Published: May 2011

The purpose of this note is to point out that the difference in the ideal -electronic thermal conductivity between an alloy and a pure metal can be estimated from the corresponding difference in the ideal electrical resistivity, using the Wiedemann-Franz law. This allows the separation of the thermal conductivity into an electronic and a lattice component to be made with greater confidence, particularly at liquid oxygen temperatures.
The Optimum Line Width for the Transition Used in a Reflection Cavity Maser Amplifier
Authors: Troup GJ
Published: May 2011

The line width of the amplifying transition in a reflection cavity maser is shown to have an optimum value, which will give maximum amplification bandwidth at a fixed gain. Difficulties associated with achieving the optimum line width in practice for the paramagnetic maser are briefly discussed.
The Eta Carinae Nebula and Centaurus A Near 1400mc/s. I. Observations
Authors: Hindman JV , Wade CM
Published: May 2011

Observations of two strong southern radio sources, the Eta Carinae Nebula (NGC 3372) and Centaurus A (13S4A), at a frequency near 1400 Mc/s, are described. The observations were made with a 36 ft transit-mounted paraboloidal aerial and a 21 cm hydrogen-line receiver modified for the reception of continuum radiation. The flux density of the Eta Carinae Nebula near 1400Mc/sis5� 82 X 10-24Wm-2 (c/s)-\ with an estimated uncertainty of less than �20 per cent. This source appears to be fairly symmetrical, with a strong central condensation.
Spins and Parities of Levels of 9Be Below 15 MeV
Authors: Thies HH , Spicer BM
Published: May 2011

In a recent study of the cross section of the reaction 9Be(y,n) (Thies, Spicer, and Baglin 1959), distinct maxima were observed at 11�25 and 13 �25 MeV. The maximum at 11�25 MeV was identified with the known level at 11�3 MeV and the 13 �25 MeV maximum was attributed to absorption by one level at that energy. The nearly equal widths of the 11�25 and 13 �25 MeV peaks justify this assumption. These peaks were attributed to M1 or E1 absorption by Thies, Spicer, and Baglin (1959).
Periodicities in Solar Radio Noise Emission
Authors: Gerson NC
Published: May 2011

In a recent article, Roberts (1958) described solar radio wave emissions in the range 40-80 Mc/s. The investigations were a continuation of work initiated earlier by Wild and McCready (1950) on the dynamic radio-frequency spectrum, and by Wild, Murray, and Rowe (1954) employing a 40-240 Mc/s spectrograph.
An Investigation of the Speed of the Solar Disturbances Responsible for Type III Radio Bursts
Authors: Wild JP , Sheridan KV , Neylan AA
Published: May 2011

The paper describes an investigation aimed at finding out whether solar radio bursts of spectral type III are due to disturbances which travel out through the corona with velocities exceeding O�lc, as predicted by the well-known hypothesis that the emissions are due to plasma oscillations. If the proposition is correct, emissions at different frequencies would be generated at different levels in the corona-the lower the frequency the higher the source. This property is tested by simultaneous directional observations at a number of frequencies between 40 and 70 Mc/s, using a swept-frequency interferometer.
The Ionosphere of Jupiter
Authors: Rishbeth H
Published: May 2011

It has been suggested that the radio-frequency emissions from Jupiter are due to plasma oscillations in the planet's ionosphere (e.g. Gardner and Shain 1958). This note shows that, according to standard theory, sufficient ionization may be produced by solar radiation; but it does not attempt to explain the actual cause of the disturbances.
Measurements of n?g Coincidences in the Reaction 10B (d, n?)11C
Authors: McDonell JA , Sargood DG , Moroney JR , Prescott JR
Published: May 2011

The energies of some neutron groups leading to low excited states of "C in the reaction lOB(d,ny)"C have been measured. These lead to values of 4�3�0�3 MeV and 6�53 � O' 02 MeV for the energies of the second and fourth excited states respectively. y-Ray spectra have also been studied in coincidence with different neutron groups. Ground state transitions were observed from the second, third, and fourth excited states, together with cascade decays of the fourth excited state through each of the second and third. Deductions from these y-ray spectra considerably reduce the number of spin possibilities which have been found for these levels by other workers.
Alpha?Particles from the Reaction 7Li(p,g)8Be(a)4He
Authors: Gemmell DS
Published: May 2011

The OI:-particle spectrum from the reaction 7Li(p,y)8Be*(0I:)4He has been determined in coincidence with y-rays_ The results indicate that, apart from the broad 2� 9 MeV level, there are no additional levels between the ground state and 7 MeV with intensities greater than 3 per cent. of the 2 . 9 MeV level. It is shown that the shape of the 2 -9 MeV level can be fitted satisfactorily by a dispersion formula if a large value for the reduced width of the level is assumed.
Cross Sections for the Interaction of 14·5 MeV Neutrons with Manganese and Cobalt
Authors: Weigold E
Published: May 2011

Cross sections for (n,p), (n,2n), and (n,lX) reactions have been extensively investigated for neutron energies near 14 MeV. However, there are still some gaps, and the present investigations were undertaken to provide neutron crosssection data for nuclei near the proton number 28. Although manganese and cobalt are both monoisotopic elements and, therefore, relatively simple to study by activation techniques, very few measurements have, in fact, been reported.
Comment on Multilayer Dielectric Filters
Authors: Armstrong HL
Published: May 2011

A recent note by Gascoigne (1959) on transmission in multilayer dielectric filters is interesting as an example of an adoption to a given problem of a result from an entirely different problem, namely, the Kronig-Penney model for metal lattices. However, one may wonder whether, in the long run, it would not be more economical of time, especially for students, to notice that the multilayer filter, the Kronig-Penney lattice, and for that matter many other problems, are all essentially forms of the same thing.
Relative Intensity of the 17·2 and 14·3 MeV Gamma Rays from the 7Li(p,G)8Be Reaction
Authors: Mainsbridge B
Published: May 2011

Radiation from proton capture in 7Li is known to consist of two principal components of energy (17�2+~.Ep) and (14'3+~Ep)MeV, corresponding to transitions to the ground state and first excited state of sBe respectively (Walker and McDaniel 1948). Resonances in the reaction are known to exist at Ep=441 keY, 1�03 and 2�1 MeV (Bonner and Evans 1948; Kraus 1954; Price 1954) and the relative intensity of the two y-rays is known to vary in the neighbourhood of the 441 keY resonance (Campbell 1956). It is not known if the intensity ratio varies in the region of the 1030 keY resonance and this experiment was designed to repeat the measurements of Campbell and extend the investigation to the higher resonance.
The Structure of Bismuth at Low Temperatures
Authors: Barrett CS
Published: May 2011

A precision determination of the displacement parameter of zone-refined bismuth containing less than 0�3 parts per million of spectroscopically detectable impurity has been carried out as a function of temperature. Procedures were used that minimize uncertainties in integrated intensities due to extinction, absorption, temperature factor, dispersion and f-curve errors, and statistical errors. The parameter bId, where d is the spacing of the (Ill) rhombohedral planes of one sub-lattice and b is the displacement of the other sub-lattice (111) planes from these, is 0�40437�0�00008 at 4�2 oK, 0�40403�0�00008 at 78 oK, and 0�4041:1:0�0005 at 296�2 oK; the rhombohedral. parameter, u, corresponding to these values is, respectively, 0�23406, 0�23400, and. 0�23401. The small but presumably significant dependence on temperature at low temperatures is in disagreement with predictions of a theory of Blount and Cohen and. may signify a lessening of resistance to the atom displacement from simple cubic, due to thermal expansion of the structure. Powder patterns yielded 57.314, 57�28., and 57�23. � for the rhombohedral angle at 4�2, 78, and 304 oK respectively.
Band Structure of Monovalent Metals and Their Alloys
Authors: Klemens PG
Published: May 2011

The consequences of the Bloch theory of the conduction properties of metals can be evaluated only for a band of spherical Fermi surface, isotropic in all respects. Quantitative comparison with observations is thus possible only for the monovalent metals. It appears that even the monovalent metals do not satisfy this requirement, but that their Fermi surface departs significantly from sphericity. The information derived from the various conduction properties and the electronic specific heat is discussed, paying attention to Umklapp processes and phonon drag effects. The thermoelectric power is difficult to interpret. Systematic measurements of the changes of various physical properties on alloying may provide useful information.
High Temperature Dielectric Breakdown of Alkali Halides
Authors: O'Dwyer JJ
Published: May 2011

In the high temperature region much of the experimental work on the dielectric breakdown of the alkali halides is apparently conflicting. If, however, it is assumed that, breakdown is thermal in nature instead of intrinsic, reasons can be given which reduce the difference between various sets of existing experimental results. A calcula� t,ion of the thermal breakdown strength is given based on the assumption that the electrical conductivity is principally ionic. The magnitude and temperature variation of the breakdown strength is given correctly without disposable constants. Some suggestions are given for experimental work which may clear up outstanding difficulties.
The Influence of Temperature and Strain Rate on the Flow Stress of Magnesium Single Crystals
Authors: Basinski ZS
Published: May 2011

The temperature and strain rate-dependence of the flow stress of magnesium single crystals was measured in the temperature range 1� 45-248 oK. Some incidental observations were also made on the form of the stress-strain curves and the appearance of Blip lines. The deformation characteristics show close similarity with those of the face-centred cubic metals.
The Instability of Plastic Flow of Metals at Very Low Temperatures. II.
Authors: Basinski ZS
Published: May 2011

Evidence is presented to show that the load drops observed in most metals at very low temperatures arise from thermal instability rather than mechanical instability of the lattice. Measurements of the temperature rise are described.
A Low Temperature Yield Instability in Iron
Authors: Lean JB
Published: May 2011

Polycrystalline specimens of a 0�07% C steel were tested in tension at liquid air temperatures. Under particular conditions of temperature and strain rate, following the upper yield point, the recorded stress descended below the lower yield stress then returned to the lower yield stress quasi. elastically thus forming a serration on the stress-strain curve. The magnitude of the serration depended on the difference between the upper and lower yield stresses, on the rigidity of the testing machine employed, and on the applied strain rate.
X-Ray Measurement of Twin Faulting in Face-centred Cubic Metals
Authors: Warren BE
Published: May 2011

It was shown by Paterson that in a cold�worked face-centred cubic metal, deformation faults produce a peak shift, and twin faults produce a peak asymmetry. If the peak shape is represented by a Fourier series, the asymmetry is expressed by the sine terms. However, the evaluation of the sine coefficients is difficult, due to overlapping of the tails of neighbouring refleotions and uncertainty in the peak origin. In this paper, a method is developed which combines the tails of the (Ill) and (200) reflections. This allows a determination of the twin fault probability in face-centred cubic metals which is more nearly independent of overlapping of the tails and choice of the peak origin.
Field Emission Through Dielectric Layers
Authors: Gomer R
Published: May 2011

Field emission experiments on the adsorption of inert gases on tungsten have shown the presence of stepwise multilayer adsorption. It is possible to obtain emission data through these layers. It turns out; that after suitable corrections for the reduction in field by dielectric effects a thinning of the field emission barrier remains. This is attributed to the fact that individual inert gas atoms represent short-range but deep potential holes (as in ordinary scattering) and so make the barrier more transparent. It is possible to treat the effect quantitatively in two approximations. One is due to Fermi and yields scattering lengths. The other consists of neglecting electronic motion transverse to the barrier, thereby making the problem one-dimensional and results in potential well dimensions. It is possible to calculate theoretical Fermi leugths for various assumed well shapes and dimensions. This is done for square wells and used to compare the results of the two approximations, in terms of the effective nuclear charges required to produce matching of the experimental Fermi lengths with the experimental well dimensions. Reasonable values of Z result for neon, argon, krypton, and xenon_ Since the zero of the potential wells lies above that of the tunnelling electrons these experiments represent in fact scattering of negative energy electrons.
Bombardment of Metals by Inert Gas Ions
Authors: Ogilvie GJ
Published: May 2011

When the surface of a metal crystal is bombarded by inert gas ions, metal atoms are knocked off the surface in certain preferred directions. Evidence is presented to show that some atoms are also knocked into the crystal. A thin disoriented surface layer appears which, if the crystal is an alloy, is of uniform but different composition from that of the original crystal, The importance of these findings to some current ideas about damage due to bombardment is briefly discussed and it is shown that present theories do not account satisfactorily for the observations.
Nucleation and Growth of Ice Crystals Upon Crystalline Substrates
Authors: Fletcher NH
Published: May 2011

The importance of various surface imperfections in the nucleation of ice crystals iR considered and it is concluded that dislocations are not preferred nucleation sites, whereas steps and re-entrant corners do encourage nucleation. Expressions are derived for the height of the free energy barrier in several important cases, and the retention of embryos under unsaturated conditions is discussed. Embryos initially grow by twodimensional nucleation, but ultimately a dislocation growth mechanism becomes more important. There is not yet enough experimental evidence to decide upon the reality of the entropy effect, previousl:y- proposed, which inhibits nucleation upon certain CITRta] faces.
The Photographic Process as a Diatomic Reaction
Authors: Candler C
Published: May 2011

If sensitive areas exist in unexposed crystals, the number of grains which develop on exposure is given by the Poisson law, and this conflicts with experiment; but, if a development centre is formed in a diatomic reaction triggered by P trapped electrons, the fraction n of the grains capable of development after an exposure E is
Zone Theory of Liquids
Authors: Makinson REB , Roberts AP
Published: May 2011

A one-dimensional model is considered in which the potential energy of an electron is nearly periodic over short distances but has no long.range order.
Susceptibility of Chromium?Based Alloys of Transition Elements
Authors: Lomer WM
Published: May 2011

The magnetic properties of chromium�based alloys with the transition metals are very varied. Below room temperature it is believed that chromium is antiferrcmagnetic and in this paper we investigate briefly the nature of the influence of this antiferrcmagnetic matrix on the properties of dilute solutions of atoms carrying weIl�defined local moments of their own. It is shown that various anomalies in the susceptibility-temperature relations can be rationalized in terms of a model involving small spin orientation forces arising from the antiferromagnetism. Alloying with vanadium appears to reduce the spin moment on the chromium atoms, but to introduce no localized spins itself. The temperature.independent contribution of cobalt in solution is interpreted in terms of local spins locked by the antiferromagnetism of the matrix. The :results so far obtained suggest that careful specific heat measurements in the range 0--100 OK may disclose very significant anomalies in many of. these alloys.
The Constant Flux Problem in Non-uniform Exponential Media
Authors: Wilson PR
Published: May 2011

A description is given of radiative transfer, under conditions of constant flux, in a semi-infinite mediUm in which the attenuation coefficient increases exponentially with depth, and has small sinusoidal variations in a direction parallel to the surface.
Rayleigh Wave Dispersion for a Single Layer on an Elastic Half Space
Authors: Bolt BA , Butcher JC
Published: May 2011

Numerical solutions of the period equation for Rayleigh waves in a single surface layer were calculated using the SILLIAC computer at the University of Sydney. Values of the phase and group velocities for both the fundamental and first higher mode are tabulated against period for eleven models. These related models allow a sensitivity analysis of the effect of variation in the seismic parameters.
Southern Hemisphere Meteor Shower Activity in July and August
Authors: Weiss AA
Published: May 2011

Observations of the radiant positions and the activities of the 3-Aquarids and three minor showers of July and August, obtained with high resolution radio equipment at Adelaide from 1957 to 1959, are given in detail. Data for the 3-Aquarids are combined with similar observations in 1953 to obtain the radiant ephemeris