Ferromagnetic resonance in polycrystalline ferrites with high magnetic anisotropy

The ferromagnetic resonance absorption line is computed in polycrystalline ferrites in the independent grain approximation taking account of the magnetic crystallographic and magnetostriction anisotropies. The results obtained show that the influence of elastic stresses on the shape of the absorption line is analogous to the effect of the magnetic crystallographic anisotropy.Translated from Izvestiya VUZ. Fizika, No. 1, pp. 9–16, January, 1972.     

Методика измерения к омплексной диэлектр ической проницаемости и нели нейных свойств диэле ктриков В диапазоне дециметр овых волн

. . .     

Das Anhaften von Exzitonen an Störstellen des Kristallgitters

Zusammenfassung Es wird der Proze des Anhaftens von Exzitonen an Vakanzen und F-Zentren in den Ionenkristallen studiert. Die Bewegung der Exzitonen im Felde der Vakanz und des F-Zentrums wird in adiabatischer Annäherung untersucht. Mit Hilfe der klassischen Methoden werden die Wirkungsquerschnitte des Anhaftens des Exzitons an den Vakanzen und F-Zentren bestimmt und diskutiert.

---

F- . F- . F- .

     

Quantitative method for determination of fibre texture in wires I. Principle of method and analytical expression of absorption factor

An X-ray diffraction method is described for the quantitative determination of the fibre texture in cylindrical specimens (wires), which does not require specimen preparation. The integrated intensity of the diffracted radiation from a certain atomic plane is measured in the direction parallel to the plane determined by the axis of the wire and by the direct beam for different orientations of the axis of the wire. These measurements can be carried out in practice using an X-ray counter diffractometer or Weissenberg goniometer. The pole figure is determined from the dependence of the diffracted intensity on the orientation of the wire after correcting the intensities for the absorption of radiation in the specimen. The geometric arrangement enables the absorption factor to be calculated analytically. Its form was verified experimentally by measuring the dependence of the intensity of the 220 reflection on the orientation of the axis of a cylindrical specimen of Al containing randomly oriented crystals.

---

I.

( ), . , , , . . , . . 220 .

---

---

The author wishes to thank Z. iký for help in carrying out the measurements and calculations.     

The vacuum and lightcone quantization of interaction Hamiltonians

Let denote the conformally invariant neutral free scalar field on ×S ⁿ. The naive lightcone Hamiltonian for a ^p interaction is given by c^p, where C denotes a lightcone in ×S ⁿ, and the Wick power is relative to the free vacuum. We show that this sesquilinear form annihilates the free vacuum if n3 is odd, p>2, and p(n–1)0 mod 4.     

The geometric equation of dislocation dynamics

Recent advances in the continuum theory of dislocations have been achieved mainly in two directions: (1) the differential geometric (non-linear) theory of stationary dislocations, and (2) the formal linear dislocation dynamics. These two are unified here to form a differential geometric dynamical theory of continuous distributions of dislocations. To begin with, the basic concepts of the geometric theory are briefly summed up. The fundamental geometric equation of time-dependent distortions is derived first in a physically instructive elementary way and afterwards by means of exact differential geometry. A symmetrized form of the equation is given in terms of deformations or the metric tensor. The physical meaning of a previously introduced dislocation current tensor is discussed. A general form of the continuity equation for the dislocation current is then given. Thereafter the forces acting on dislocations are dealt with in connection with energy dissipation during plastic deformation and Ohm's law for dislocations, which has been introduced recently. The dislocation conductivity in simple cubic crystals is discussed. Finally, an invariant partition of the torsion (or dislocation) tensor is introduced. The semi-symmetrical part of this tensor corresponds to volume deformations, while the remainder is associated with shape deformations only. The main unsolved problems are enumerated, and some concluding remarks, concerned with the correspondence between dislocation theory on the one hand and general relativity and differential geometry on the other, are added.

---

, , : (1) - ( ) (2) . . . , . , . . . , , . . ( ). , . , , , .

     

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.

---

. , . , .

     

Maximal violation of Bell's inequalities is generic in quantum field theory

Under weak technical assumptions on a net of local von Neumann algebras {A(O)} in a Hilbert space , which are fulfilled by any net associated to a quantum field satisfying the standard axioms, it is shown that for every vector state in there exist observables localized in complementary wedge-shaped regions in Minkowski space-time that maximally violate Bell's inequalities in the state . If, in addition, the algebras corresponding to wedge-shaped regions are injective (which is known to be true in many examples), then the maximal violation occurs in any state on () given by a density matrix.     

К ТЕОРИИ РЕЗОНАНСНОЙ МИГРАЦИИ ЭНЕРГИИ ВОЗ БУЖДЕНИЯ В ТВЕРДЫХ ТЕЛАХ

- - . - .     

Diffusion in a one-dimensional gas of hard point particles

We simulate the classical diffusion of a particle of massM in an infinite one-dimensional system of hard point particles of massm in equilibrium. Each computer run corresponds to about 10⁸ collisions of the diffusive particle. We find that (t) 1/t fort large enough, and a crossover from an M m regime where=2 to=3 forM=m. The diffusion constant has a sharp maximum atM=m. We study moments x(t)² and x(t)⁴, and examine the behavior ofq ² (t)=x(t)⁴/3x(t)²². We find thatq(t)1 (consistent with a normal distribution) in theM limit (for all timest) and in the t limit for allM. On sabbatical leave from IVIC-Instituto Venezolano de Investigaciones Cientificas.     

The effect of microsegregation on the generation of dislocations in zinc single crystals

The applicability of Tiller's considerations on the production of dislocations is proved. The density of dislocations appearing during impurity microsegregation increases with increasing rate of growth as a consequence of the corresponding change in the effective distribution coefficient. The real value of C at the microsegregation boundaries is at least twice as great as the average value of the concentration of impurities in the crystal in question.

---

. , , . C , .

     

The interaction of pions with deuterons

Summary There has been remarkable experimental and theoretical progress in the field ofd interactions in the last few years. Within the uncertainties of the theory the experimental data in thed breakup and thed elastic scattering reaction can be fairly well reproduced. Theoretical problems remain in the absorption channel, but there is a hope that with a few additional measurements of tensor polarization and spin transfer observables in this reaction a partial wave amplitude analysis may localize the theoretical difficulties. In addition it is very important to provide data on the deuteron tensor polarizations and the spin transfer parameters for thed elastic scattering reaction in order to obtain a reliable set of phase shifts, which may reveal resonance structures in this reaction channel.Invited talk to the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.     

Металлографические методы определепия нлотности дислокаци й В монокристаллах германия

, , . , .1) . .     

ПОТОК ЭНЕРГИИ ЧЕРЕЗ Д ИЭЛЕКТРИЧЕСКИЙ ТОНК ИЙ СЛОЙ ПРИ НАРУШЕННОМ ПОЛНО М ОТРАЖЕНИИ

, .

---

Energy flux through thin dielectric film when total reflection is disturbed

It is shown that the energy flux through a thin dielectric film when total reflection is disturbed is brought about by the interference Poynting vector.

     

ЭЛЕКТРИЧЕСКАЯ ЭКВИВ АЛЕНТНАЯ СХЕМА ЗАТУХАЮЩИХ КОЛЕБАНИ Й СДВИГА ПЬЕЗОЭЛЕКТРИЧЕСКИХ СТЕРЖНЕЙ

n - , - .     

Radiation effects in the production and decay of ψ mesons by leptons

A new expression _e is obtained for resonance in the reaction e⁺e^– ar ^+– with allowance for the radiative corrections, which also contain the emission of hard photons by the final leptons and the final value of the energy resolution E. An expression is obtained for the total probability of radiative lepton decay. A numerical analysis of the experimental data is made for the reaction ^+–, and the parameters e⁺e^– (3, 1) e⁺e^–, and _e ² /, _e, and are determined for (3, 1) resonance-with allowance for the radiative corrections.This paper was read (November 17–21, 1975) at a session on high-energy physics of the Department of Nuclear Physics of the Academy of Sciences of the USSR.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 29–34, March, 1977.     

К СПЕКТРУ ПОГЛОЩЕНИЯ АМОРФНОГО СЕЛЕНА В ИНФРАКРАСНОЙ ОБЛАС ТИ

0,6 25 . , , . , 13,4 20,4 , , , . . , . .

---

A contribution to the absorption spectrum of amorphous selenium in the infra-red region

The absorption spectrum of amorphous selenium was measured in the region of 0·6 to 25 on samples of high purity and homogeneity. The absorption bands of amorphous and liquid sulphur were also measured in the same wave-length region. The measurements showed that the absorption bands 13·4 and 20·4 , appearing in the spectrum of amorphous selenium, are its intrinsic absorption bands and are not caused by impurities, as some authors think. The similarity between the infra-red spectra of selenium and sulphur is shown.

     

Über die an „Schwachen“ Grenzflächen Entstehenden Kopfwellen

Zusammenfassung In der vorliegenden Arbeit werden die Kopfwellen untersucht, die beim Auffallen einer harmonischen Schall-Kugelwelle auf die Ebene Grenzfläche zwischen zwei flüssigen Medien entstehen. Vorausgesetzt wird, daß die Grenzfläche schwach ist, d. h. daß die Geschwindigkeit der Schallwellen im Medium mit der Erregungsquelle nur um weniges kleiner ist als die Geschwindigkeit der Schallwellen im Medium ohne die Quelle.

---

,

, . , , . . .

     

Влияние давления на а бсорбцию галогенидо в серебра. Часть II

AgBr, Agcl AgI — 160°C. AgBr AgCl . AgI .     

Exponential decay in the stark effect

LetH=–+V+Fx ₁ withV(x ₁,x ) analytic in the first variable andV(x ₁+ia, x ) bounded and decreasing to zero asx for eacha . Let be an eigenvector of –+V with negative eigenvalue. Among our results we show that forF0, (,e ^–H ) decays exponentially at a rate governed by the positions of the resonances ofH. This exponential decay is in marked contrast to conventional atomic resonances for which power law decay is the rule.Research supported by NSF Grant No. MCS 78-00101.