The complex conductivity of the plasma of a d-c glow discharge in Ne

In paper [1] Fang derived an expression for the complex conductivity of plasma assuming that the distribution function of the electrons is Maxwellian and the collision frequency is directly proportional to their velocity. Since the assumptions are approximately satisfied in the positive column of a d-c glow discharge in Ne, the applicability of Fang's relation is investigated for this case.

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[1] , . , .

     

Current distributions in a two-dimensional random-resistor network

The current and logarithm-of-the-current distributionsn(i) andn(ln i) on bond diluted two-dimensional random-resistor networks at the percolation threshold are studied by a modified transfer matrix method. Thek th moment (–9k8) of n(ln i) i.e., ln i&^k, is found to scale with the linear sizeL as (InL)^(k). The exponents (k) are not inconsistent with the recent theoretical prediction (k)=k, with deviations which may be attributed to severe finitesize effects. For small currents, ln n(y)–, yielding information on the threshold below which the multifractality of (i) breaks down. Our numerical results for the moments of the currents are consistent with other available results.     

A note on the Watanabe theory of weak interactions

It is shown that according to the Watanabe theory of weak interactions a resonant scattering of electrons by protons must take place. The resonant energy depends on the massm _B of the intermediate boson. Form _B=2300m _e this energy is about 213 MeV in the centre of the mass system (c. m. s.). The energy width at resonance is 1·4 MeV.

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, . , , . _{m B}=2300_{m B} , 213 MeV -. 1,4 MeV.

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The author would like to thank Professor V. Votruba for suggesting this note and for valuable advice and help during the work.     

Inertial range spectrum of a fractal model for turbulence

The present study deals with a model for 3D turbulence which is based on a fractal set ink-space (massM(k)logk, i.e.d _f=0). The energy spectrumE(_k) is calculated by a method similar to the Monte Carlo renormalization technique of Ma [1]. To apply this we decouple the set into next-neighbour pairs of energy shells.E _k is calculated iteratively by simulating the pairs. Their rough scales are forced and their fine scales are damped by an eddy viscosity ^e. We start in the viscous range where ^e is neglected. An intertial range shows up with a spectrumE(k)k^–, =1.68±0.07, and an eddy viscosity ^e(k)k ^-,=1.3±. The possible benefit for the simulation of turbulent flows is pointed out.     

Локалъная чувствите лъностъ фотокатодов фотоумножителей

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The local sensitivity of photo-multiplier photo-cathodes

The influence of the non-uniform distribution of the sensitivity of a photo-multiplier photo-cathode on the spectrum shape of the output pulses from a scintillation detector is studied. Methods of scanning the local sensitivity and determining its distribution function are described. The theory was compared qualitatively with measurement on a slow-neutron detector from a mixture of zinc sulphate and boric acid.

     

The rotation of bloch walls

A Bloch wall has an integral magnetic moment which is due to the spatial distribution of the magnetic moments of the spin. The external magnetic field thus acts on the wall with a torque, which leads to the rotation of the sub-domains and therefore to deformation of the walls. A theory of this rotation is given and from it a microphysical model of the undulatory surface structure in uniaxial ferromagnets is derived. Experiments performed on magnetoplumbite single crystals fully confirm the theoretical assumptions.

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. , , . , . , , .

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Our thanks go to J. Fousek and Z. Málek who by reading this paper contributed greatly to the clarity of its presentation.     

On X-ray measurements of residual stresses in materials with lattice strain gradient

The non-linear distribution of lattice strain ³¹⁰vs sin² observed on the surface of a polished steel specimen can be interpreted by tri-axial stress state with surface components of stress tensor ₁₁(0)= ₂₂(0) and gradientsg ₁₁= ₁₁/T, g ₃₃= ₃₃/T. The distribution of experimental values is duscussed from the viewpoint of various ways of calculating ₁₁.The authors would like to thank Dr. J. Musil, D. Sc. of the Institute of Physics of Czechoslovak Academy of Sciences for kindly providing the samples which made possible this study.     

ИЗЛУЧЕНИЕ ЧЕРЕНКОВА ПРОСТРАНСТВЕННОГО З АРЯДА В ВОЛНОВОДАХ И В НЕОГР АНИЧЕННОЙ СРЕДЕ

, - e . -. , .     

Resonant magnetopolaron effects in parabolic quantum wells in a tilted magnetic field

We study the resonant magnetopolaron effects in parabolic quantum wells in a tilted magnetic field. The renormalization of the first excited level, which is resonant with the ground state level plus one longitudinal-optical phonon is calculated at the resonance using an improved resonance approximation to be E= where is the polaron coupling constant. The exponent and the factor are calculated in dependence on the tilt angle of the magnetic field and the confinement energy.     

Die magnetische Suszeptibilität der ternären Systeme halbleitender Verbindungen

Zusammenfassung Im vorliegenden Artikel wird der Versuch unternommen, die für die Suszeptibilität der binären Systeme zutreffenden empirischen Beziehungen auf die ternären halbleitenden Systeme auszudehnen. Die Richtigkeit der Erwägungen wird an den Systemen Zn-Cd-Sb, In-Ga-Te und an einigen festen Lösungen anderer halbleitender Verbindungen überprüft. Im Artikel wird weiter gezeigt, daß sich im Falle, wenn sich die Suszeptibilitäten der Komponenten des ternären Systems additiv verhalten, zur Berechnung der molaren Suszeptibilität einer festen Lösung die Mischungsregel verwenden läßt, was im Gegenteil in diesem Falle als Kriterium dienen kann, ob zwei den Erfordernissen der Additivität der Suszeptibilitäten der Bestandteile Genüge leistende Stoffe eine feste Lösung oder ein mehrphasiges System bilden.

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, , . Zn-Cd-Sb, In-Ga-Te . , , , , , , , , , .

     

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 ПРОБЛЕМЕ МАГНИТНОЙ ФОКУСИРОВКИ ПУЧКОВ ЭЛЕКТРОНОВ, ЭМИТТИРО ВАННЫХ С ТЕПЛОВЫМИ СКОРОСТЯМИ

, . — , , — - . , - -. - .     

РАДИОМЕТРИЯ В ГЕОФИЗ ИКЕ

cmambe ome, - . - .     

The quantum efficiency of the internal photo-electric effect in indium antimonide

A method is described for measuring the relative quantum efficiency of the internal photo-electric effect in semi-conductors by simultaneously measuring the photo-magnetoelectric and photo-conductive effect. The results of measurements on indium antimonide are given. The quantum efficiency begins to increase if the energy of the photon exceeds 0·47 eVat room temperature. The quantum efficiency as a function of the energy of the photon is analysed on the basis of the conception of impact ionization and it is shown that a study of the structure of this curve can supply information on the, band structure of a semi-conductor in the region of high energies of electrons and holes.

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. . , 0,47 eV . , .

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The authors thank M. Závtová and M. Vantuchová for efficient help with the measurements, K. mirous and V. Vrchovská for preparing the material, E. Antoník for critical remarks and M. Matyá and A. Müller for determining the constants of the material.     

Role of time in the sum-over-histories framework for gravity

I sketch a self-contained framework for quantum mechanics based on its path-integral or sum-over-histories formulation. The framework is very close to that for classical stochastic processes like Brownian motion, and its interpretation requires neither measurement nor state-vector as a basic notion. The rules for forming probabilities are nonclassical in two ways: they use complex amplitudes, and they (apparently unavoidably) require one to truncate the histories at a collapse time, which can be chosen arbitrarily far into the future. Adapting this framework to gravity yields a formulation of quantum gravity with a fully spacetime character, thereby overcoming the frozen nature of the canonical formalism. Within the proposed adaptation, the value of the collapse time is identified with total elapsed spacetime four-volume. Interestingly, this turns the cosmological constant into an essentially classical constant of integration, removing the need for microscopic fine tuning to obtain an experimentally viable value for it. Some implications of the V = T rule for quantum cosmology are also discussed.     

Optical and magneto-optical effects in semi-conductor crystals

The complicated line structure of the fundamental absorption edge and the effect of magneto-optical oscillations (which are general properties of crystals) open up good possibilities for the study of band structure and exciton states.From a survey of the facts observed lately it follows that the real existence of the exciton is almost certain although no experiment has yet been performed, which would provide direct experimental proof of its motion in the crystal. The evidence of the motion of excitons in the crystal can be determined from effects based on spatial dispersion effects. The observed optical anisotropy of absorption in a Cu₂O cubic crystal (due to spatial dispersion) and the quadrupole character of the exciton linen=1 confirm the motion of exciton through the crystal.The fine structure of the spectral curve for photoconductivity (an effect that is also common to all crystals), which is directly connected with the exciton absorption structure, also testifies to the motion of excitons.The exciton structure of the absorption edge and also the connected effect of edge emission enable the band structure and its splitting to be studied.The determination of the splitting of the exciton lines and edge of continuous absorption under the influence of oriented elastic deformation and the study of the state of polarization of the split components provides a new method for the study of band structure.The study of the Zeeman effect for lines of exciton, absorption in crystals can supply data on the exciton motion and on the complicated band structure in crystals. Special detailed data on the band structure can be obtained from studies in polarized light. From the effect of magneto-optical oscillations we can decide with great exactness the band width of the forbidden zone and obtain data which are in good agreement with those obtained by other methods.

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- , , . , , , , . , . — —, , n=1 . — , , — , . , - . () , . , , , , . - . . , , .

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Address delivered at International Conference on Semi-conductor Physics, Prague, Czechoslovakia, September 1960.     

Theory of ferromagnetic resonance line shape in insulators

The paper discusses the absorption of the energy of a high-frequency field by a magnetic sample from the point of view of the interaction of spin waves with photons and spin waves amongst themselves. A general expression for the form of the absorption curve is derived, using the method known from the quantum theory of radiation and assuming very weak fields.

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. , , .

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The author thanks S. Krupika, Candidate of Sciences, for the exceptional interest taken in this work, for advice and a number of helpful and critical remarks.     

Screening Effect Due to Heavy Lower Tails in One-Dimensional Parabolic Anderson Model

We consider the large-time behavior of the solution to the parabolic Anderson problem _tu=u+u with initial data u(0, ·)=1 and non-positive finite i.i.d. potentials . Unlike in dimensions d2, the almost-sure decay rate of u(t, 0) as t is not determined solely by the upper tails of (0); too heavy lower tails of (0) accelerate the decay. The interpretation is that sites x with large negative (x) hamper the mass flow and hence screen off the influence of more favorable regions of the potential. The phenomenon is unique to d=1. The result answers an open question from our previous study [BK00] of this model in general dimension.     

К ВОПРОСУ О ФОТОПРОВО ДИМОСТИ ФОТОГРАФИЧЕСКОЙ ЭМУ ЛьСИИ

) . , , , ; , , . . , .     

The influence of a small electric perturbation on the electroluminescence curve of ZnS-Cu

The influence of a small electric perturbation of variable phase on the brightness wave of alternating electroluminescence of ZnS-Cu is investigated. The results are compared with the model described in [1]. The increase in the number of ionized activators after switching on the electric field is studied and is found to reach equilibrium. after about 50 to 150 sec.

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ZnS-Cu

ZnS-Cu. , [1]. , 50–150 s.

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In conclusion the author thanks M. Mokonová for cooperation in evaluating the results of measurement.