Table of contents

The article sets forth the theory of the influence of multiple scattering on the radiation of ultrarelativistic particles in matter. The classical theory of the Landau-Pomeranchuk effect of suppression of the radiation of relativistic particles in an amorphous medium is presented both in the simple form given by the authors and in a refined form due to Migdal. It is shown that in investigation of the influence of multiple scattering on the radiation of fast particles in matter it is possible to use a functional integration method which permits construction of a quantitative theory of the effect in both amorphous and crystalline media. The question of the possibility of stochastic motion of fast charged particles in a crystal is discussed. The general regularities and distinctive features in processes of radiation of relativistic particles in amorphous and crystalline media and also in intense external electromagnetic fields are discussed.

The present state of research on the resonant scattering of electrons by atoms and ions is described. A comparison is made of the various theoretical methods used to describe these processes: the method of strong coupling of channels, the diagonalization method, the R-matrix method, etc. For the most part, the latest experimental data over the past five years (through the end of 1984) are reported. Only isolated references are made to 1985 studies. The thrust of the review is to determine the role played by autoionizing states in resonant scattering and to analyze how well the existing theoretical studies describe the experimental data available. It can be concluded from this analysis that we have a fairly clear picture of the mechanism for resonant scattering processes and that the description is qualitatively good. However, an important role is played here by electron-electron correlations. Further research is required for an accurate account of these correlations.

This paper, which contains the text of the introductory talk at the 13th International Conference on High Energy Accelerators at Novosibirsk in August 1986, presents a review of the contemporary status and prospects of high-energy physics.

The subject of lasers in acoustics covers the following topics: lasers as unique sources and detectors of sound, coherent optical analysis of signals in multichannel acoustic data systems, and laser-acoustic technology. The results of research at the interfaces between acoustics, quantum and physical electronics, and fiber and integrated optics provide opportunities for developing new methods for experiments in physics and new technical means which can be used to carry out tasks that cannot be performed by traditional methods. An analysis is made of the characteristics of laser generation of sound in condensed media and of the applications of lasers for remote detection of acoustic fields and vibrations. The principles of operation of fiber-optic sound detectors are described. An analysis is made of the possibility of using optical generation and detection of sound in technology and in instruments for nondestructive testing, as well as in multichannel acoustic data systems.

Modern methods for studying in situ the kinetics of crystals growth in solution are briefly reviewed. A Michelson laser interferometer makes it possible to measure simultaneously the normal and tangential growth rates of crystal faces as well as the slope angle of dislocation growth humps.