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Showing papers in "Reports on Progress in Physics in 1973"


Journal ArticleDOI
TL;DR: It was first shown in 1960 that rapid quenching of certain alloys from the melt could form completely extended solid solutions, new metastable crystalline phases, and amorphous solid phases as discussed by the authors.
Abstract: It was first shown in 1960 that rapid quenching of certain alloys from the melt could form completely extended solid solutions, new metastable crystalline phases, and amorphous solid phases. These effects were attributable to the high cooling rates (>or approximately=105 K s-1) from the melt achieved by new techniques of rapidly spreading a few milligrams of liquid alloy into a thin layer in close contact with a good heat conductor (splat cooling). A comprehensive review of developments to data which have resulted from the application of this technique in laboratories throughout the world is presented. It includes an analysis of the range of methods now available for quenching the melt and of present understanding of how they form and quench specimens. The structural features observed as-quenched are then discussed under the divisions of microstructure and extended solid solubility, and of formation of both metastable crystalline and amorphous solid phases. A survey of the response of the as-quenched microstructure to annealing then precedes treatment of the properties and applications of splat-cooled alloys. It is concluded that splat cooling is being established in ever widening fields of study as a tool for controlling structure and properties, and that further applications can be anticipated.

250 citations


Journal ArticleDOI
TL;DR: In this paper, the dynamics of a rapidly rotating electrically conducting fluid in the presence of a corotating magnetic field are studied. But the authors focus on the dynamics in the case of a single magnetic field.
Abstract: The author reviews work on the dynamics of a rapidly rotating electrically conducting fluid in the presence of a corotating magnetic field. While the separate action of either rotation or a magnetic field produces strong dynamical constraints, their simultaneous action can result in comparatively weak net constraints and novel phenomena then arise. A systematic account of these phenomena is given and certain applications to natural systems (with emphasis on the dynamics of the Earth's liquid core) are outlined.

212 citations


Journal ArticleDOI
TL;DR: In this article, the statistical-thermodynamic theory of a molecular network is outlined, and the main conclusions, in the form of stress-strain relations, etc., are presented and compared with experimental data.
Abstract: The relation of rubbers to other classes of polymers and the molecular basis of rubber elasticity are briefly examined. The methods used in the quantitative development of the statistical-thermodynamic theory of a molecular network are outlined, and the main conclusions, in the form of stress-strain relations, etc, are presented and compared with experimental data. Also examines the photoelastic properties of rubbers from both theoretical and experimental standpoints and discusses in detail the evidence derived from photoelastic studies on the statistical segment length in the molecular chain and its relation to intramolecular energy barriers. The thermodynamic analysis of stress-temperature data for rubber and other polymers, with particular reference to the internal energy and entropy changes during extension under constant pressure or constant volume conditions is studied. The phenomena of swelling in liquids is considered.

207 citations


Journal ArticleDOI
TL;DR: In this paper, a general free energy functional for a superconductor is given and different cases where it can be reduced to a Ginzburg-Landau form or to a simple generalization of this form is studied.
Abstract: In this review the author describes how the simple Ginzburg-Landau approach lies in the heart of the general theory of superconductors. The reader is introduced to the handling of the theory and to the numerous possibilities of applications. A general free energy functional for a superconductor is given and the different cases where it can be reduced to a Ginzburg-Landau form or to a simple generalization of this form is studied. It is emphasized that applications are not restricted to thermo-dynamical ones as the Ginzburg-Landau approach can be used in the calculation of dissipative phenomena. The possibility of an extension to the time-dependent phenomena is discussed in detail to present the difficult problems which arise in that case. The gapless regime of type II superconductors is given as an example.

165 citations


Journal ArticleDOI
TL;DR: There has been considerable progress in the study of the structure and elementary excitations of liquid helium as discussed by the authors, which has largely arisen from the development and refinement of neutron, X-ray and light scattering techniques and also from more detailed ultrasonic measurements.
Abstract: During the past decade there has been considerable progress in the study of the structure and elementary excitations of liquid helium. This has largely arisen from the development and refinement of neutron, X-ray and light scattering techniques and also from more detailed ultrasonic measurements. A large part of this review is concerned with describing the results of these experiments and their implications for theories of liquid helium. During the last few years there has also been considerable progress made in the theory of the excitations in liquid helium. These developments are briefly reviewed and the most promising lines of development indicated.

151 citations


Journal ArticleDOI
TL;DR: In this paper, the consequences of the coupling between the charge carriers and the optical phonons are discussed and applied to a wide range of experimental observations in semiconducting and in insulating solids.
Abstract: The properties of charge carriers in solids can be modified greatly by their real and virtual interactions with optical phonons. These effects differ in two particular ways from the changes induced by interactions with acoustic lattice modes. Firstly, those optical modes which interact with carriers are closely monochromatic. Sharply defined structure can therefore appear in many experimental observations, including optical properties, photoconductivity, tunnelling, the magnetoresistance observed under quantum-limit conditions and a range of coupled mode phenomena embracing boht single carriers and plasma modes. Secondly, in materials of a polar nature the coupling of carriers to the optical modes is particularly strong and the resulting scattering probabilities and changes in effective mass can be large. Nevertheless, significant effects produced by the optical modes may be observed in homopolar semiconductors such as silicon and germanium. This article reviews the consequences of the coupling between the carriers and the optical phonons. The theory of such interactions is developed at length and then applied to a wide range of experimental observations in semiconducting and in insulating solids.

143 citations


Journal ArticleDOI
TL;DR: The theory of synchrotron radiation is well understood as mentioned in this paper, and its application as an XUV light source is reviewed, and this unique source is compared with conventional XV light sources.
Abstract: The theory of synchrotron radiation is well understood. Those aspects relevant to its application as an XUV light source are reviewed, and this unique source is compared with conventional XUV light sources. A number of spectrometers are described that have been developed specifically for use with synchrotron radiation and that overcome some of the problems inherent in utilizing such sources. The greater part of the review describes experiments in atomic, molecular and solid state spectroscopy that have benefited substantially from the application of these intense, highly polarized XUV continua. The wavelength distribution of intensity of the synchrotron radiation can be calculated from known accelerator parameters if the total number of orbiting electrons can be determined. Synchrotrons can hopefully become absolute standards of intensity throughout the XUV spectral region.

82 citations


Journal ArticleDOI
TL;DR: A review of the theoretical and experimental work which has shown the possibility of forming bound states of an electron or an exciton with an optical phonon is given in this paper, where the existence of bound and hybrid states must have a marked effect on a number of physical phenomena, in particular the optical properties.
Abstract: A review is given of the theoretical and experimental work which has shown the possibility of forming bound states of an electron or an exciton with an optical phonon. Most attention is devoted to wide-band systems, in which the width of the electron (or exciton) band is larger than the phonon frequency; this is the normal situation for semiconductors and ionic crystals. A discussion is also given of excitons in molecular crystals, which are treated as narrow-band systems; here the existence of bound states is not related to the presence of a threshold in the exciton spectrum. The existence of bound and hybrid state must have a marked effect on a number of physical phenomena, in particular the optical properties, as has already been demonstrated in a series of experiments.

70 citations


Journal ArticleDOI
TL;DR: In this article, a review of the three major aspects of metal machining: the physical characteristics of chip formation, the properties and operating conditions of cutting tools, and the condition of the final product.
Abstract: This review considers the three major aspects of metal machining: the physical characteristics of chip formation, the properties and operating conditions of cutting tools, and the condition of the final product. There is a brief account of specialized metal-removal techniques and numerical and computer control of modern lathes and milling machines. The contributions of applied physics to metal cutting are emphasized throughout. The dependence of chip formation on the deformation and fracture behaviour of the workpiece and the friction conditions between chip and tool are described. Because of these extreme conditions the choice of tool materials is very restricted.

70 citations


Journal ArticleDOI
TL;DR: In this article, a detailed discussion of low energy neutron scattering in the energy range of molecular translation and hindered rotation demonstrates both the difficulties involved and several instances where this technique has shed new light on the problem of molecular motions.
Abstract: The theory is developed in terms of monatomic systems in order to demonstrate the relationships between the momentum and energy profiles of the scattered neutrons and the properties of the scattering nuclei. An indication is then given of how this framework may be expanded to deal with molecular systems. A brief discussion of the more commonly used experimental methods is included. Because of difficulties of interpretation and the lower resolution compared to other spectroscopic techniques, neutron scattering methods have been most successfully applied to certain well defined problems in molecular spectroscopy. A detailed discussion of low energy neutron scattering in the energy range of molecular translation and hindered rotation demonstrates both the difficulties involved and several instances where this technique has shed new light on the problem of molecular motions. The review concludes with a survey of neutron scattering of the dynamics of macromolecules.

49 citations


Journal ArticleDOI
TL;DR: In this article, the authors considered the information required for computer models of the atmosphere and for the consideration of the possible mechanisms for climatic change and provided a selection of references for further reading.
Abstract: Observation of radiation reflected, scattered or emitted in various regions of the electromagnetic spectrum can yield information about the structure of a planetary atmosphere. Instrumentation for the measurement of temperature, density, and composition and for cloud imaging is described, methods of information retrieval from radiometric observations are discussed, and some of the results for the atmospheres of Earth, Mars and Venus are presented. Further developments are considered particularly in the light of the information required for computer models of the atmosphere and for the consideration of the possible mechanisms for climatic change. A selection of references for further reading is included.

Journal ArticleDOI
TL;DR: In this paper, the properties of birefringent crystals are reviewed for phase-matching and nonlinear coefficient prediction, with particular emphasis on phase matching and effective nonlinear coefficients.
Abstract: Describes the phenomena fundamental to efficient optical frequency mixing of laser beams in transparent, acentric birefringent crystals, with particular emphasis on phase-matching, effective nonlinear coefficients and results for focused beams. Methods for measuring nonlinear coefficients, for predicting them by semi-empirical rules and for seeking improved crystals are reviewed. The properties of crystals known at this time to be useful for efficient phase-matched optical frequency mixing are tabulated; features important for the growth and preparation of samples with high optical quality are discussed. Recent achievements in applying the crystals are reviewed in sections on optical second-harmonic generation of laser light, optical parametric oscillators as tunable laser-like sources, infrared signal and image upconverters and difference-frequency generators. Applications to other technologies (piezoelectricity, pyroelectricity, electro-optic modulation) are briefly mentioned. Prospects of developing improved crystals or of using existing crystals in more sophisticated ways are assessed.

Journal ArticleDOI
TL;DR: The application of ultralow temperature techniques to many fields of physics and some of the most fundamental results thereby obtained are reviewed briefly as mentioned in this paper, in particular, Fermi liquids, dilute magnetic alloys, superconductivity, magnetic cooperative phenomena, nuclear structure, elementary particle scattering and astrophysical applications.
Abstract: Three relatively new methods which are capable of producing temperatures in the milli- or microkelvin region, that is, dilution refrigeration, Pomeranchuk cooling, and several variations of nuclear demagnetization, are first discussed in some detail. The application of ultralow temperature techniques to many fields of physics and some of the most fundamental results thereby obtained are then reviewed briefly. In particular, Fermi liquids, dilute magnetic alloys, superconductivity, magnetic cooperative phenomena, nuclear structure, elementary particle scattering and astrophysical applications are discussed.

Journal ArticleDOI
TL;DR: In this paper, the authors summarized the present knowledge of the stellar content of our galaxy and discussed at some length the use of this knowledge in creating a dynamical framework that can be used in the attempt to understand galaxies in general.
Abstract: The authors have summarized the present knowledge of the stellar content of our galaxy and discussed at some length the use of this knowledge in creating a dynamical framework that can be used in the attempt to understand galaxies in general.

Journal ArticleDOI
TL;DR: In this paper, the analysis and interpretation of meson-baryon scattering at center-of-mass energies of less than 2.25 GeV/c2 or correspondingly laboratory momenta of less 2.0 GeV /c.
Abstract: This review is concerned with the analysis and interpretation of meson-baryon scattering at centre-of-mass energies of less than 2.25 GeV/c2 or, correspondingly, laboratory momenta of less than 2.0 GeV/c. The subject primarily under discussion is that of resonances. The concept of a resonance in the context of scattering is discussed, methods of partial wave analysis are outlined and the techniques of extracting resonance information detailed. The classification of the resonances within SU(3), SU(6) and the quark model and the success of SU(3) in relating their partial widths is described.

Journal ArticleDOI
J A Bastin1
TL;DR: In this article, the authors describe the application of the concepts and laws of physics to the study of the formation, structure and properties of the surface layers of the moon, and the effect of solar electromagnetic radiation on the Moon's surface is described.
Abstract: This article describes the application of the concepts and laws of physics to the study of the formation, structure and properties of the surface layers of the moon. Both impact and internal mechanisms for the origin of the lunar surface features are considered. The effect of solar electromagnetic radiation on the Moon's surface is described, from which information about the chemical composition, microstructure and thermal properties of the surface may be deduced. The interaction of the moon with the electromagnetic field of the solar wind is discussed. Bombardment of the lunar surface by the solar wind and by cosmic ray particles is also considered, both as a means of determining the individual histories of lunar rock samples and of investigating possible variations in the flux of such particles over cosmological time scales. Seismic measurements made on the lunar surface are described.

Journal ArticleDOI
TL;DR: In this article, a review of the use of large aperture seismic arrays to detect seismic events is presented, focusing mainly on LASA, the largest aperture seismic array in the world.
Abstract: After outlining routine seismological concepts the review describes present array installations. The theory of array processing schemes is outlined. Operational capabilities are presented for the routine operation of arrays to detect seismic events. Research prospects with arrays are described for a wide variety of problems connected with the seismic source and propagation phenomena. Emphasis is mainly on LASA, the large aperture seismic array in Montana which has been operating since 1965. Newer arrays in Norway and Alaska are described briefly. Finally, the problem of detection and identification of explosions, which was the original impetus for the installation of arrays, is reconsidered in the light of advances made possible by large arrays.

Journal ArticleDOI
TL;DR: The Navier-Stokes equations are an unclosed set of statistical relations as mentioned in this paper, and the problem of finding the dependence of the pair correlation function on the separation of the two measuring points in space and time is difficult.
Abstract: Turbulence theory is difficult because the Navier-Stokes equations are an unclosed set of statistical relations. The review begins with an account of the problem of closure, and shows that this problem is evaded rather than solved by the methods now used for practical calculation: examples of the use of these methods are given. The bulk of the review is devoted to more fundamental procedures whose aim is to find the dependence of the pair correlation function on the separation of the two measuring points in space and time. This is done by making closure assumptions which are, at the least, free from arbitrary constants and which have some claim to uniqueness at the lowest level of complexity. The application of these theories to homogeneous isotropic turbulence is described. The review closes with an account of a problem in nuclear engineering which highlights both the defects of existing methods of calculation for turbulent flows, and the need for the better methods that the more fundamental procedures may one day offer.

Journal ArticleDOI
TL;DR: In this paper, the optical difference between true oceanic and coastal water is emphasized, including energy losses, refractive index effects, polarization, non-optical uses of optical measurements and measuring instruments.
Abstract: Oceanic optical properties are reviewed. Topics covered include energy losses, refractive index effects, polarization, non- optical uses of optical measurements and measuring instruments. Throughout the article the optical difference between true oceanic and coastal water is emphasized.

Journal ArticleDOI
TL;DR: The growth of high energy physics after the advent of particle accelerators in the GeV energy range is closely linked with the bubble chamber technique as mentioned in this paper, and the importance of the technique in the past and its future applications are discussed.
Abstract: The growth of high energy physics after the advent of particle accelerators in the GeV energy range is closely linked with the bubble chamber technique. By means of a series of examples in strong and weak interaction physics both the early and more recent work is examined. The importance of the technique in the past and its future applications are discussed. Four appendices give thumbnail descriptions of some of the definitions and theory used in the article.

Journal ArticleDOI
TL;DR: In this article, the CERN intersecting storage rings and the experimental work based on them, with a discussion of results obtained in the first twenty months of operation, are discussed, with particular emphasis on their use for obtaining high energies in the centre of mass system.
Abstract: Some of the general considerations governing the usefulness and the practicability of storage rings, in which circulating beams of elementary particles are maintained for periods long in relation to the time for a single revolution in orbit are presented. Single storage rings for experiments on free particles are discussed in one section, which is followed by a chapter on colliding beam storage rings. The storage ring is presented as a device allowing investigation of processes which are inaccessible with the conventional arrangement of beam and stationary target. The latter part of the report is concerned with intersecting storage rings for proton-proton collisions, with particular emphasis on their use for obtaining high energies in the centre of mass system. The major part of this section is devoted to the CERN intersecting storage rings and the experimental work based on them, with a discussion of results obtained in the first twenty months of operation.