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.

---

, . - , ( ), , . .

     

Локалъная чувствите лъностъ фотокатодов фотоумножителей

. . .

---

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.

     

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.

---

, . , , . , .

     

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].

---

, , [1–4, 6].

     

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.

---

. Johansson. , , . , , , . .

     

Power-law falloff in the kosterlitz-Thouless phase of a two-dimensional lattice Coulomb gas

We give a rigorous proof of power-law falloff in the Kosterlitz-Thouless phase of a two-dimensional Coulomb gas in the sense that there exists a critical inverse temperaturegb and a constant >0 such that for all> and all external charges R we have , whereG (x) is the two-point external charges correlation function,=dist(, Z), and for 0$$ " align="middle" border="0"> . In the case of a hard-core or standard Coulomb gas with activityz, we may choose=(z) such that(z)24 asz0.     

тЕОРИь И стРУктУРА тЕ МпЕРАтУРНОгО ИжОБРА жЕНИь

. , , , . .

---

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.

     

Bunching phenomena during electron injection into the betatron

Under favourable conditions electrons injected into the betatron give rise to high-frequency oscillations. An experimental investigation of the properties of the oscillations is presented, in which new experimental material is added to an earlier paper [1] and the hypothesis regarding the nature of the oscillations is corrected.The oscillations are due to azimuthal bunching of the injected or captured electrons. The bunching is caused by a regenerative amplification of space-charge density fluctuations. The amplification is produced by the negative mass instability mechanism theoretically investigated by Nielsen, Sessler and Symon [2] and Kolomenskij and Lebedev [3].Bunching of the injected electrons is the primary cause of the capture of electrons injected into a static or slowly varying magnetic field. Bunching of the captured electrons represents a limitation in the magnitude of the capturable charge.

---

, I.

, , . , [1] . . . , [2] [3]. , . .

     

Новый тип рентгеновс кого спектрографа

. 1', . . .     

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.

---

Co⁵⁹(p,n) E _p 6,5 MeV

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

---

---

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.     

The semi-conducting properties of CdSnAs2

The paper gives the results of measuring the temperature dependence of the electrical conductivity(T), the Hall coefficientR _H (T) and the magnetic susceptibility(T) forn-type CdSnAs₂. The effective mass of the electrons was determined by analysis of the measured dependences on the basis of the simple theory for an isotropic non-degenerate semi-conductor. It was found to bem _n /m ₀=2×10^–2 in the intrinsic region and does not depend on the temperature; the energy gap ise _g ⁰=0·26 eV and the molar susceptibility of the CdSnAs₂ lattice _G ^mol=–112× ×10^–6. The mobility of the electrons in the intrinsic region reaches a value of _n =25 000 cm²V^–1sec^–1 at 500°K and decreases exponentially _n T ^–1.67 with rising temperature. The density of CdSnAs₂ was determined pyknometrically,g9=5·35 g cm^–3. The measurements were made on ann-type polycrystalline sample consisting of crystals a few millimetres in diameter, which at a temperature of 100°K had a free electron concentration ofn _s =6×10¹⁶ cm^–3.

---

CdSnAs₂

(T), R _H (T) (T) CdSnAs₂ . m _n /m ₀= =2.10^–2, ; E _G ⁰=0,26 eV, CdSnAs_{2 G} ^mol= =–112.10^–6. 500°K _n =25 000 cm²V^–1sec^–1 , _n T ^–1,67. CdSnAs₂ =5,35 g cm^–3. , , 100°K n _s =6.10¹⁶cm^–3.

---

---

The authors would like to thank Mr. P. Jansa for help in measuring the temperature dependence of the magnetic susceptibility.     

Струи паров материал ов электродов нри кратковременном электрическом разря де с Большой силой тока

. . , .

---

The vapour jets of electrode material of a short-time high-intensity electric discharge

The velocity of vapours from electrodes and the values of the electric gradient of the channel were measured. An explanation is given of the dependence of the discharge rate of the vapours on the electrode material and the thermal origin of the jets is confirmed. The validity of the results is shown for the case of a different experimental arrangement, or the formation of other types of discharges on electrodes.

     

The connection between low-gradient form of the positive column in oxygen and moving striations

The method of sliding photomultipliers was used to study the connection between two forms of the positive column in oxygen — the so-called low-gradientT-form and the highgradientH-form — and the presence of moving striations in the positive column. It was shown that in theT-form of a positive column striations are always present which move from the cathode to anode with a velocity of several thousand metres/sec. The highgradient form of theH-positive column, on the other hand, is not striated. The non-single-valuedness of the value of the longitudinal electric field in a discharge in oxygen is thus explained by the presence or absence of phenomena of a time variable character.

---

— - H - — . , - , /. , , . , , , .

     

Determination of accuracy in measuring the parameters of tetragonal and hexagonal lattices

The procedure for determining the accuracy when measuring the parameters of tetragonal and hexagonal lattices is described. The accuracy can easily be calculated for all common methods by means of graphically represented functions. The relations derived can be used as quantitative criteria for the suitability of the combination of lines from which the lattice parameters are to be determined.

---

. , . , .

     

ПРОВОДИМОСТЬ СРЕДНЕ Й ЧАСТИ КАНАЛА КОНДЕНСИРОВАННЫХ РА ЗРНДОВ

. , . . - , 500 10 000 30 500 . - , .     

ТЕОРИЯ ДИФФУЗИИ „ЛОК АЛИЗОВАННЫХ“ ЭКСИТО НОВ В ТВЕРДЫХ ТЕЛАХ

.     

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.

---

ZnS: Cu

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

     

Diquark Model for J/ψ Baryonic Decays

The baryonic decays of J/ provide a new way to study the internal structure of baryons. We apply a simple diquark model to the calculation of the decay cross-sections for the reactions J/ , N^*(1440), ^*N^*, and ⁰⁰. The results are different from those given by the ordinary constituent quark model. Hence these reactions may provide a new check of two different pictures for the baryons.     

Experimentelle Untersuchungen über das Verteilungsgesetz der Ferromagnetischen Bereiche nach dem Kriterium der Koerzitivkraft

Zusammenfassung Aus Messungen der inneren Reibung in magnetischen Feldern, die durch das Überlagern eines magnetischen Wechselfeldes über ein magnetisches Gleichfeld zustande gekommen sind, werden Schlußfolgerungen gezogen über die Art, wie sich die Verteilung der ferromagnetischen Bereiche nach dem Standpunkt der Koerzitivkraft im Magnetisierungsprozeß in einem magnetischen Gleichfeld verändert. Aus Messungen der inneren Reibung in magnetischen Wechselfeldern mit gleicher Amplitude aber verschiedenen Frequenzen wird die Schlußfolgerung gezogen, daß die Wände jener Bereiche, welche verschiedene Koerzitivkräfte haben, erzwungene Schwingungen mit verschiedener Geschwindigkeit aufweisen.

---

, , , . , , , .

     

БЕТАТРОННЫЕ КОЛЕБАН ИЯ В УСКОРИТЕЛЕ С ОБЩИМ ПОЛЕМ I

, . . . , , . , . , . .

---

Betatron oscillations in an accelerator with a general field I

The paper gives a linear theory of equilibrium trajectories in an accelerator with a generalized magnetostatic field, the components of which are defined on a general rotation surface. Equations of motion of the particles in natural coordinates are derived with respect to the change in energy and dissipative force. A system of equilibrium trajectories is found in the general form. Conditions for the field components on the reference surface, necessary for the existence of equilibrium trajectories, for the conservation of their geometric similarities and for maintaining the constancy of the frequencies of the betatron oscillations, are derived. A condition is also derived which must be satisfied by the reference surface in order to conserve constant circular frequency of the particles. It is seen that it is not possible to find a field for an accelerator with an exactly constant circular frequency and with constant frequencies of the betatron oscillation in the relativistic energy region. An ultra-relativistic cyclotron with such properties is realizable.