ИССЛЕДОВАНИЕ ЭРОЗИЙ НОГО ДЕЙСТВИЯ ИМПУЛЬ СНЯХ ЭЛЕКТРИЧЕСКИХ РАЗРЯ ДОВ С СЛАБЫМ ТОКОМ

50–100 , 1–2 1–10 . - . - . , , - . -.     

On the photo-electroluminescence of ZnS-Cu

The influence of weak ultra-violet irradiation on the brightness waves of electroluminescence is investigated for two types of ZnS-Cuphosphors. The observed effects (increase in brightness in the primary peak and its phase shift, the disappearance of the secondary peak) are explained on the basis of present-day conceptions on electroluminescence.

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ZnS-Cu

ZnS-Cu. ( , ) .

     

The elastic coupling between longitudinal and transversal vibrations оf isotropic rods II. Rods of circular cross-section

The new approximative method for calculating the frequencies of longitudinal vibrations of isotropic homogeneous rods described in part I. is used for rods of circular crosssection. Similarly to the rods of rectangular cross-section there does not exist any dead zone of frequencies.

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II.

, I. (. . 366), . , , .

     

ФОТОЭЛЕКТРИЧЕСКИЕ С ВОЙСТВА АНТИМОНИДА ГАЛЛИЯ

(GaSb), - 120–340 °K. : E₂=(0,773–0,75.10^–6 T ²) ., - .     

The change in primary extinction during decomposition of a super saturated solid solution 1. System Al-Ag

On the basis of the correlation of diffraction data (intensity and width) of a precipitate with the intensity of reflection of a matrix solid solution it is shown that the change in primary extinction during the decomposition of a solid solution of Agin Alis caused by the precipitation of the phase Ag₂Aland not by the production of lattice defects (zones, stacking faults).

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I. Al-Ag

( ) , Ag Al Ag₂Al, ( , ).

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Reported in part at the VIth Scientific Technical Conference on the Application of X-rays held in Leningrad in 1958.

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The author thanks M. Mikovský for preparing the single crystals of the alloy Al-Ag having a high primary extinction and J. Laek and Prof. J. Bedná for carefully checking their homogeneity and chemical composition.     

Circular edge dislocation loop

A solution of the stress, deformation and deformation energy is given for an edge dislocation with its dislocation line having the shape of a circle in an unlimited isotropic medium. The possibility of using this solution in studying the dislocation loop in a crystal is discussed.

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The author thanks M. imanová for carrying out the numerical calculations and J. Kaczér and B. esták for remarks and discussion.     

Rapid graphical determination of the radial intensity distribution of the small-angle scattering of X-rays from the measured data

The radially symmetrical small-angle scattering pattern (which would be obtained by the use of a direct beam having a point-like cross section) is in practice distorted, especially by the beam height. To eliminate this distortion the integration of a set of curves based on the derivative of the measured intensity distribution is required to derive the true radial intensity distribution. A rapid graphical method of plotting these curves is described and its accuracy is proved on an example. It is further shown that the radial intensity distribution can be determined in principle using the values of the measured curve instead of its derivative.

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( ) . , . . . , .

     

Static and Vibrational Properties of Transition Metals

A model pseudopotential depending on an effective core radius but otherwise parameter free is proposed to study the equation of state by incorporating the s-d hybridization effects. Very recently proposed screening function due to Sarkar et al has been used to obtain the screened form factor. The equations of state for Cu, Ta, Mo, W and Pt have been studied up to the pressure of 1000 GPa. The vibrational properties such as phonon dispersion curves (in q and r space), phonon density of states, mode Grüneisen parameters, maximum frequency _max, mean frequency , ^21/2 = (/ ^-1)^1/2 and fundamental frequency ² and static properties such as dynamical elastic constants of rhodium and iridium are also calculated. The theoretical results are compared with experimental findings wherever possible. A good agreement between theoretical investigations and experimental findings has confirmed our formulation.     

Замечание К теории по степенного возникновения подви жных слоев в плазме инертных газов

[1] t _B , t _B . , t _B , . .

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A note on the theory of the successive production of moving striations in the plasma of inert gases

Approximate expressions are derived on the basis of Pekárek's theoretical paper [1] for the period of the maximum t_B of a wave packet produced by the passage of a wave of stratification before the aperture of a photomultiplier, and for its time width in the half-height t_B. The relaxation time of a wave of stratification, following from the theory [1], can thus be calculated by means of the experimentally measured velocity of motion of the maximum of a wave packet u and its width t_B. The calculation is supplemented by numerical data on the magnitude of errors committed by using approximate expressions.

     

Logically independent von Neumann lattices

Three definitions of logical independence of two von Neumann latticesP₁,P₂ of two sub-von Neumann algebras ₁, ₂ of a von Neumann algebra are given and the relations of the definitions clarified. It is shown that under weak assumptions the following notion, called logical independence is the strongest:A B 0 for any 0 A P₁, 0 B P₂. Propositions relating logical independence ofP₁,P₂ toC ^*-independence,W ^* independence, and strict locality of ₁, ₂ are presented.     

Enhancement of activated decay of metastable states by resonant pumping

We consider the effect of a high-frequency pumping cost on the escape rate of a classical underdamped Brownian particle out of a deep potential well. The energy dependence of the oscillation frequency(E) is assumed to be weak on the scale of thermal energy,_E(0)T(0)T/V₀ (0)[_E(0) is the derivative of(E) atE= 0,V ₀ is the barrier height,V ₀ T]. The quadratic-in- contribution to the decay rate is calculated in two different regimes: (1) for the case of resonance of the pumping frequency with the nth harmonic of the internal motion at an energye, when = n(e); (2) for a rollout region of the basic resonance near the bottom of the potential well, when ¦-(0)¦ and is the damping coefficient. In the latter case the absorption spectrum and the enhancement of the decay rate are calculated as functions of two reduced parameters, the anharmonicity of the potential,v _E (0)T/, and the resonance mismatch, [ —(0)]/. It is shown that the effect of the pumping increases with diminishing ¦v¦ and at small v is proportional tov ^–1. In this regime, the dependence on is stepwise: the pumping contribution is large for v > 0 and small for v < 0. In the frame of our theory, the decay rate is invariant against the simultaneous alternation of the signs of andv. The spectrum of the energy absorption has the standard Lorentzian shape in the absence of anharmonicity,v=0, and with increasing of ¦v¦ shifts and widens retaining its bell-shape form.     

О взаимодействии экс итонов с колебаниями кристаллической реш етки

, - . : - . - .     

The inelastic reactions πp→λ(⌆) K with allowance for the contribution of branch cuts

The method of complex angular moments is used to analyze the experimental data on the inelastic reactions p ()K, taking into account branch cuts in the j-plane in the eikonal approximation. An optical model for the backward scattering is considered. Agreement with experiment is obtained in the region of small angles for the reactions (⁰)K⁰. In the case of ^–P K⁰(^–K⁺) processes, agreement is obtained with the experimental results for large (180) scattering angles.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 26–30, August, 1972.     

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.     

On the mass spectrum of the 2+1 gauge-Higgs lattice quantum field theory

We investigate the mass spectrum of a 2+1 lattice gauge-Higgs quantum field theory with Wilson action A _P+A _H, whereA _P(A _H) is the gauge (gauge-Higgs) interaction. We determine the complete spectrum exactly for all , >0 by an explicit diagonalization of the gauge invariant transfer matrix in the approximation that the interaction terms in the spatial directions are omitted; all gauge invariant eigenfunctions are generated directly. For fixed momentum the energy spectrum is pure point and disjoint simple planar loops and strings are energy eigenfunctions. However, depending on the gauge group and Higgs representations, there are bound state energy eigenfunctions not of this form. The approximate model has a rich particle spectrum with level crossings and we expect that it provides an intuitive picture of the number and location of bound states and resonances in the full model for small , >0. We determine the mass spectrum, obtaining convergent expansions for the first two groups of masses above the vacuum, for small , and confirm our expectations.Research partially supported by CNPq, Brasil     

Results of three-year systematic measurement of nuclear fall-out

A survey is given of the results of measuring the radioactivity of rain-out from 1. 11. 1956 to 1. 2. 1960 and of fall-out from 1. 11. 1958 to 1. 2. 1960.The temporary cessation of nuclear weapon tests from 1. 11. 1958 became apparent in the second half-year after the cessation (from 1. 5 to 31. 10. 1959) by a decrease in the cumulative activity to 45% of the value for the first half-year (from 1. 11. 1958 to 30. 4. 1959). At the end of 1959 another decrease was apparent.It was shown on the basis of long-term investigation into the activity that the samples of fall-out with greater activity contain relatively very little admixture from earlier nuclear tests so that in the period of a few weeks to months the sets of fission products may be regarded as practically isolated. The exponentn in the relationA=at ^–n is most frequently 1.2 for the period of the first four mounths and for older samples is most oftenn=1.5. The energy of the beta and gamma rays from fall-out was estimated on the basis of absorption measurements. It was shown that the quality of the beta radiation varies with the age of the samples.A brief survey is given of the results of determining the Sr 90 content in fall-out and milk, and of the methods of physical evidence of Sr 90 used.

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1. 11. 1956 1. 2. 1960 1. 11. 1958 1. 2. 1960. 1. 11. 1958 , ( 1. 5. 31. 10. 1959) 45% ( 1. 11. 1958 30. 4. 1959). 1959 . . , , . n A=at ^–n 4 1,2; n=1,5. - - . , - . Sr⁹⁰ . Sr⁹⁰.

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The author thanks Prof. F. Bhounek, member of the Czechoslovak Academy of Sciences, for valuable advice during this work.     

The movement of single 90° domain walls of BaTiO3 in an alternating electric field

Single crystals of BaTiO₃, containing one 90° domain wall, were used to study the origin and character of the movement of such a wall in an alternating electric field having a frequency of 50 c/s. The experimental results are discussed from the phenomenological point of view.

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90- BaTiO₃

iO₃, 90- , 50 Hz. .

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The authors would like to thank A. Glanc for preparing the crystals for measurement, V. Dvoák, J. Kaczér and V. Janovec for fruitful discussions.     

Влияние эмиссионных свойств анода на характеристики сч етчиков гейгера-мюлл ера

.

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The influence of the emission properties of an anode on the characteristics of GM counters

The hitherto unknown mechanism of the production of false pulses is investigated and its influence on the characteristics of counters is discussed.

     

РЕАКЦИЯ ОБРАЗОВАНИЯ ПОЗИТРОНИЯ В ГАЗАХ

The investigation of positronium angular distributions in the positron-positronium pick-up reactions in gases is considered as a new method for studying electron wave functions in molecules. The methods of direct nuclear reactions were used. The basic approximation of the present paper is the Born-approximation.Angular distributions are distinguished by reactions with electrons from atomic and molecular orbits. The most advantageous region of positron energy is the 20–100 eV region.

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- . . - AH CCCP . . .     

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, , . , , - .