Single crystal diffraction pattern of germanium

The diffraction pattern for the (111)-reflection of germanium was measured by means of the three-crystal arrangement and compared with dynamical theory. The results obtained indicate the possibility of using germanium crystals for precise measurements in X-ray spectroscopy.

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(111) . .

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In conclusion the authors thank Ing. Hrubý for preparing the germanium single crystals and participating in the preparation of the surfaces; they are also indebted to V. Smutná, R. ída and A. Irra for the care with which they carried out various tasks and V. Horáková for carefully performing the numerical calculations.     

Polarization of photo-luminescence of ZnS: Cu monocrystals

Different models of luminescence centres are discussed on the basis of measurements of the composition of ZnS monocrystal photo-luminescence in different polarizations and temperature dependence of the degree of polarization. Those of the models submitted by Birman, which assume the polarization to be due to the different force of the oscillators for transitions withEc andEc, or models assuming luminescence polarization to be due to the orientation of the luminescence centres, agree with the results of experiments, i.e. the temperature independence of the degree of polarization and the conformable spectral composition of both polarizations. It is also shown that measurements made up to now of the degree of polarization must be taken as orientational as a consequence of the depolarizing influence of the diffused rays of luminescence on its value.

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ZnS: Cu

ZnS , . , . . , , , E E, , . , , - .

     

Summation formulae in the theory of thin films

On the basis of general summation formulae for light reflected and transmitted by a thin film the author derives formulae for a thin dielectric film, for a thin metallic film and for a system of thin dielectric films. This solution is based on Stokes's principle of reversibility, which is the idea unifying the cases into one theory. In conclusion he gives the solution of a general case, dealing with light reflected and transmitted by a system of thin dielectric and metallic films.

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, . , , . , .

     

К ВОПРОСУ ВТОРИЧНОЙ Э МИССИИ ОКСИДНЫХ КАТОДОВ

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СЕРНИСТЫЙ ТЕЛЛУР — ПО ЛУПРОВОДИОЕ СОЕДИНЕ НИЕ

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Влияние краевых поле й на ъетатронные колебания В ускорите ле С разрезным магпитом I

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The influence of fringing on betatron oscillations in an accelerator with a sectioned magnet. I

A study is made of betatron oscillations in stray fields at the edges of magnets of an accelerator having a small radius. Two approximations of the course of stray fields, chosen on the basis of measurements, help in the construction of non-linear equations of motion of the particle. Transformation matrices of the boundary regions are derived. The case when an equilibrium trajectory encloses a general angle with the edge of the magnet is also treated.

     

Chain bi-refringent filters

The paper gives new results obtained in research into and the development of chain bi-refringent filters described by the author [1–4, 6].

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, , [1–4, 6].

     

Photo-piezoelectric effect in semiconductors

A new photo-voltaic effect was observed which is caused by inhomogeneous distribution of the pressure in a semiconductor. Its production can be explained by the dependence of the energy gap on the pressure.

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, . .

     

The basic equations of the dynamics of the continuous distribution of dislocations III. special problems

The basic equations of the dynamics of the continuous distribution of dislocations analogical to Maxwell equations are derived in a series of papers [I, II, III]. The analogy of the elastic and electromagnetic fields is analyzed. In part [III] some special problems are discussed, such as the density of the forces acting on the dislocations, the energy dissipation during the movement of dislocations, which is expressed by an equation analogical to Ohm's law. The equations derived in the previous parts in four-dimensional symbolics are considered in the three-dimensional differential and integral form. It is found that in special cases the relations become the known ones of elastodynamics, hydrodynamics and the static theory of the continuous distribution of dislocations. It is found that Kröner's method of integrating the equations of the dislocation field by means of so-called incompatibility tensors is analogical to the integration of the Maxwell equations by means of Hertz vectors. The analogy between the elastic dislocation field and the electromagnetic field is discussed in detail.

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III.

, . . : , , , , . , , . , , . , . .

     

Two-quantum annihilation of polarized positrons

The cross-section for the two-quantum annihilation-in-flight of partially polarized beams of particles, obtained by using the polarization density matrix, is given. The formula includes the special results of L. A. Page [1]. The annihilation of a longitudinally polarized positron with a transversally polarized electron is discussed. Computations are made in a centre-of-mass system with summing over photon polarizations.

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Abbreviated version of a diploma-thesis for the degree graduate physicist.

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The author wishes to express his sincere gratitude to Professor V. Votruba and Dr. L. Valenta for suggesting this work and for many helpful discussions and criticisms.     

Choice of parameters of an X-ray monochromating unit

In recent papers a way of computing the monochromated wavelength distribution in some current experimental arrangements was presented. In this paper an application is shown for the Johansson monochromating unit. The conditions are indicated for attaining the desired breadth of the monochromated interval and for its maximum intensity. The analysis implies that it is not advantageous to use very narrow foci and that the crystals should be neither very perfect nor very imperfect. The optimum conditions must be found in each case separately.

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. Johansson. , , . , , , . .

     

Transport of light radiation in a spatially finite three-dimensional scattering medium

We propose a new method for solving radiation transport problems, which permits including in analytic form for the case of normal incidence the effect of spatial finiteness of the scattering medium. The formation of the light field accompanying changes in the optical parameters and optical dimensions of the medium is analyzed.this paper, we examine the simplest case of a geometry of a scattering medium in the form of a parallelipiped with optical length _x, height _y, and width _z. The analysis is performed for the case =1, _y = _z with the latter varying in the range 0.1 to . The results obtained show that the light field depends strongly on the optical dimensions of the medium. The limiting values of the optical dimensions (_y = _z), beginning with which the spatial finiteness of the medium can be neglected, are determined.Translated from Izvestiya Vysshikh Uchebnykh Zavednii, Fizika, No. 8, pp. 82–85, August, 1982.     

ЗАТУХАНИЕ КОЛЕБАНИЙ ЧАСТИЦ В ОБЩЕМ ПОЛЕ С ПЕРИОДИЧЕСКОЙ СТРУКТУРОЙ I

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The damping of particle oscillations in a general field with periodic structure I

A liner theory is derived, discussing the dynamics of particles in the region of an equilibrium orbit in a general electromagnetic field, which forms a periodic system. The total particle damping is determined from the Hamiltonian found and from dissipative forces brought out by a classical reaction radiation. Relations for the damping of the synchrotron oscillations are derived from the study of the appropriate phase space.

     

К ВОПРОСУ О ФОТОПРОВО ДИМОСТИ ФОТОГРАФИЧЕСКОЙ ЭМУ ЛьСИИ

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A contribution to direct processes in the Co59(p,n) reaction forE p ∼ 6·5 MeV

Nuclear emulsions were used to study the energy spectrum and forward-backward asymmetry of neutrons from the Co⁵⁹(p,n) reaction forE _p 6·5 MeV. It was found that the decay of the compound nucleus makes a maximum contribution of 50% to the reaction yield. Energies of some excited states of the Ni⁵⁹ nucleus were also determined.

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Co⁵⁹(p,n) E _p 6,5 MeV

- Co⁵⁹(p,n) E _p 6,5 MeV. , 50%. , Ni⁵⁹.

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The authors would like to thank all those who helped in this work, particularly all members of the cyclotron group of the Nuclear Research Institute of the Czechoslovak Academy of Sciences, who so willingly helped with the irradiation, and H. Koutová from the Faculty of Technical and Nuclear Physics, who carefully measured the emulsions. Our thanks are also due to R. Krejová from the Faculty of Technical and Nuclear Physics for developing the emulsions and J. Kopecký from the Nuclear Research Institute for providing the cobalt target.     

Die Energiezufuhr von Einem Longitudinalen Wechselmagnetfeld an Ein Torsionspendel mit Ferromagnetischer Aufhängung

Zusammenfassung In der vorliegenden Arbeit werden einige Ergebnisse, die an ferromagnetischen Proben erhalten wurden, beschrieben. Verwendet wurde Kupferdraht, auf welchen Nickelschichten von verschiedener Dicke niedergeschlagen wurden. Die Proben zeigen, daß dabei die innere Reibung im magnetischen Wechselfeld unter den Wert, der der magnetischen Sättigung entspricht, fallen kann, und daß am Torsionspendel unter bestimmten Umständen erzwungene Schwingungen entstehen.

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, . , . , , , .

     

On the electroluminescence of powdered zinc sulphide layers

The experimental study of the dependence of the electroluminescence brightness on the voltage confirms the correctness of the mechanism of electroluminescence, based on impact ionization in parts of the crystal where the electric field is concentrated. A study of the photoluminescent and electroluminescent spectra of phosphors containing two activators (copper and an element of rare earth) permits the determination of the magnitude of the volume of the crystal in which electroluminescence occurs. A study of the influence of the stored light sum on the brightness of electroluminescence and a study of the rate of growth of the variable and constant components of electroluminescence point to the fact that the excitation is transferred from the region of field concentration to the whole volume of the crystal.

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К определению самопр оизволъной иамагниченности В об ласти точки кыри

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тЕОРИь И стРУктУРА тЕ МпЕРАтУРНОгО ИжОБРА жЕНИь

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The theory and structure of the temperature image

The paper describes the theory of the formation of a temperature image when there are large temperature differences and introduces the concept of temperature distortion of an image. It also deals with the geometrical distortion of the temperature image by the longitudinal thermal conductivity of the receiver layer and gives a solution of the corresponding differential equation of the temperature image for the case of a general linear line test and general circular concentric test. Equations are derived for the temperature distributions of the temperature images of some optical lineated and circular test objects and their geometrical distortion due to the thermal conductivity of the receiver layer is investigated.

     

ЭЛЕКТРИЧЕСКАЯ ЭКВИВ АЛЕНТНАЯ СХЕМА ЗАТУХАЮЩИХ КОЛЕБАНИ Й ИЗГИБА У ПБЕЗОЭЛЕКТРИЧЕСКИ Х СТЕРЖНЕЙ

- .