Faculty of Physics
M.V.Lomonosov Moscow State University
Theoretical and mathematical physics

## The origin of magnetic fields of astrophysical objects

Moscow University Physics Bulletin 2000. 55. N 2. P. 1

In the framework of multidimensional models of the Kaluza - Klein type with consideration for the relation theory of space-time and interactions (binary geometrophysics), explanation of the origin of magnetic fields of the Earth, the Sun and other astrophysical objects is proposed.

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## Estimating string tension from finite-energy sum rules

### D.V. Meshcheryakov, V.B. Tverskoi

Moscow University Physics Bulletin 2000. 55. N 2. P. 5

In the framework of the finite-energy sum rules, with the use of the modified expression for the QCD running coupling constant, the string tension parameter is estimated.

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## Interpretation of some features of the plasmon spectrum of simple metals

### J.M. Aleshin, D.V. Peregudov

Moscow University Physics Bulletin 2000. 55. N 2. P. 8

The influence of a periodic nonuniform background on the propagation of charge density waves in simple metals is studied. It is shown that the incorporation of spatial nonuniformity in the Vlasov-Poisson equations leads to a plasmon spectrum that is qualitatively consistent with experimental data. Namely, calculations show that charge density waves decay in a nonuniform medium even at a zero quasimomentum value; at some values of the inverse lattice vector, the dispersion curve has a negative slope.

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## Substantiation of the method of maximum entropy for solution of ill-posed problems

### A.S. Leonov$^1$, A.G. Yagola$^2$

Moscow University Physics Bulletin 2000. N 2.

It is shown that various substantiations of the method of maximum entropy for solving linear ill-posed problems that have recently been suggested by a number of authors (1991-1993) can easily be obtained from general assertions of the theory of nonlinear ill-posed problems in topological spaces developed by the authors of this paper in 1986-1988. The application of this general theory gives, in particular, a simple substantiation of the method of maximum entropy for nonlinear ill-posed problems.

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## Differential-geometric criterion for kinematic integrability of equations with operators from $su(1,1)$ and $su(2)$

### A.Yu. Kolesnik

Moscow University Physics Bulletin 2000. 55. N 2. P. 16

A necessary and sufficient condition for kinematic integrability of equations with operators belonging to the Lie algebras $su(1,1)$ and $su(2)$ is proved. The suggested criterion is related to differential-geometric consideration of the corresponding classes of kinematically integrable equations and is based on the $G$-representation of partial differential equations.

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## Neutral particle radiation in electromagnetic field

### A.E. Lobanov, O.S. Pavlova

Moscow University Physics Bulletin 2000. 55. N 2. P. 19

The total radiation power of a classical neutral particle having an anomalous magnetic and an electric moment in its motion in an arbitrary electromagnetic field has been found. The result has been obtained on the assumption that the particle spin evolution is determined by the generalized Bargmann-MichelTelegdi equation.

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## Suppression of opposite-wave generation in cyclotron-resonance masers with longitudinal profiling

### A.F. Aleksandrov, V.A. Kubarev, A.V. Mikhailov

Moscow University Physics Bulletin 2000. 55. N 2. P. 23

Opposite-wave generation in cyclotron-resonance masers with linear longitudinal variation of the waveguide radius and the leading magnetic field is considered. Conditions for the generation suppression are obtained.

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Optics and spectroscopy

## Analysis of scattering properties of oxide particles on a multilayer substrate

### N.V. Grishina, Yu.A. Eremin, A.G. Sveshnikov

Moscow University Physics Bulletin 2000. 55. N 2. P. 29

Polarized light scattering by oxide microparticles located on a film-coated substrate is analyzed. To carry out computer simulation, the method of discrete sources is extended. The effect of the film and oxide layer on the particle scattering properties is studied.

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## Studying the efficiency of scintillation detectors for back-scattered electrons in SEM

### R.N. Birchenko, E.I. Rau, M.N. Filippov

Moscow University Physics Bulletin 2000. 55. N 2. P. 35

The experimental investigations conducted have shown that the scintillation detectors used in scanning electron microscopy for the registration of back.scattered electron fluxes differ noticeably in the efficiency of detection by different regions of their active part.

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## Effect of low-scale atmospheric turbulence alternation on the characteristics of narrow collimated laser beams

### T.I. Arsenyan, A.M. Zotov, P.V. Korolenko, M.S. Maganova, V.G. Makarov

Moscow University Physics Bulletin 2000. 55. N 2. P. 41

Factors affecting amplitude and phase fluctuations in detection-and-rangingtype optical systems under alternating atmospheric turbulence conditions are considered. Experimental data characterizing, as applied to a narrow collimated laser beam, the effects of random wandering, turbulence broadening, and variation of the correlation radius of the intensity fluctuations are obtained and analyzed. The sporadic radiation stochastization observed is explained by the sharp reduction of the internal turbulence scale in comparison with the average beam size.

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## Controlled holographic recording in azo-containing liquid-crystal polymer films

### A.N. Simonov, A.V. Larichev, V.1. Shmalgauzen

Moscow University Physics Bulletin 2000. 55. N 2. P. 46

The dynamics of holographic recording processes in azo-containing side-chain liquid-crystal polymer films is experimentally studied. The possibility of effective control of optical recording conditions by applying an aligning electric field and also by varying the temperature of the polymer layer is demonstrated. In a polymer film 50 $\mu$m in thickness at a diffraction efficiency of around $\sim$75%, a sensitivity of around $\sim$21 см$^2$/J is attained. High-density recording in the form of a Fourier-transform hologram is effected.

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Acoustics and molecular physics

## Spectral density of vortical velocity pulsations in a well-developed free turbulent flow

### S.G. Mikhailov

Moscow University Physics Bulletin 2000. 55. N 2. P. 52

Based on the assumption put forward as to the local character of vorticity in a free incompressible liquid flow, the vortex element of a turbulent flow is isolated and its properties are evaluated. Good agreement is found to exist between the form of the spectral density of the velocity pulsations arising as a result of the uniform transport of a random ensemble of quasistationary turbulence vortex elements by the mainstream flow and the well-known approximations of experimental data.

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Solid state physics

## The electronic spectrum and optical transitions in superlattices with quasi-localized states in the unit cell

### A.V. Dmitriev, V.V. Makeev

Moscow University Physics Bulletin 2000. 55. N 2. P. 56

For a superlattice whose unit cell contained quasi-localized electron states, the electron spectrum structure was studied and the dipole matrix element of intersubband transitions was calculated. The dispersion relation and the band structure of such a superlattice were determined. The wave functions and the electron spectrum were found to possess peculiar hybrid properties near the energy corresponding to the quasi-localized state in an isolated quantum well. The absorption coefficient of the heterostructure in this region was substantially increased.

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## On the determination of the ZnAs$_2$ band structure parameters

### V.A. Morozova, S.F. Marenkin, 0.G. Koshelev

Moscow University Physics Bulletin 2000. 55. N 2. P. 62

A method for taking into account light scattering in ZnAs$_2$ and obtaining the $\alpha^\parallel(h\nu)$ absorption spectrum was suggested. At the $E\parallel c$ polarization, the absorption edge was shown to be determined by indirect and direct allowed transitions with the energy difference 64 meV between them, which involved exciton states. For both transitions, in the temperature range $80 \div 300$ K, the forbidden band width was determined.

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## Why does the Meissner effect arise?

### N.B. Brandt, G.A. Mironova, V.V. Rzhevskii

Moscow University Physics Bulletin 2000. 55. N 2. P. 68

A possible experiment that would allow one to determine the necessary and sufficient conditions for the Meissner effect to arise in classical superconductors is described.

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## X-ray diffraction study of interatomic correlations in alloys with components having close atomic numbers (Cu-Zn and Cu-Ni)

### A.A. Katsnelson, V.M. Silonov, T.V. Skorobogatova, O.V. Kris'ko

Moscow University Physics Bulletin 2000. 55. N 2. P. 73

By the method of X-ray diffuse scattering, a short-range order in Cu-Zn alloys and short-range stratification in Cu-Ni alloys have been established.

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## Inverse reluctance in granulated ferromagnetic alloys

### A.B. Granovskii$^1$, V.A. Kovalev$^1$, J.-P. Clerc$^2$

Moscow University Physics Bulletin 2000. 55. N 2. P. 79

A model describing reluctance of granulated alloys with allowance made for the effect of $d$-electrons on current transport is proposed. Within the framework of this model, the presence of positive reluctance for a number of granulated alloys {Co-Cu, Co-Ag, etc.) and multilayers {Fe/Cr, Co/Cu, Fe/Cu, etc.) is explained.

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Geophysics

## Seismotectonic strain of lithosphere in the Aegean region

### E.V. Voronina, A.V. Lyusina

Moscow University Physics Bulletin 2000. 55. N 2. P. 83

Seismotectonic strain rate tensors, the main and effective strain rates for the lithosphere of the Aegean region have been computed. The orientation of the compressive and tensile strain axes has been determined. The relationship between possible failure of the medium and the effective strain rate has been established for the first time. Observation of strong 1991-1997 earthquakes has shown that regions of high seismic hazard are those where the strain rates are at their minimum.

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Theoretical and mathematical physics

## Statistical properties of fixed points of dynamic systems

### P.V. Elyutin

Moscow University Physics Bulletin 2000. 55. N 2. P. 90

A relative prevalence of fixed points of various classes in the phase plane for autonomous systems of the general form is studied. It is shown that saddlepoints are most frequently met, foci are more seldom, and knots are even more seldom.

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## Studying physical processes in nonperiodic highly heterogeneous media

### G.N. Medvedev, B.I. Morgunov

Moscow University Physics Bulletin 2000. 55. N 2. P. 92

Mathematical models of electrodynamical and thermomechanical processes in highly heterogeneous nonperiodic media have been considered. An iterative procedure for determining the asymptotic expansion coefficients of solutions of electrodynamics and thermoelasticity equations has been described.

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## Excitation of nonlinear waves by finite-amplitude vibrations of a sphere in a linearly deformable medium

### Wang Ning, 0.V. Rudenko

Moscow University Physics Bulletin 2000. 55. N 2. P. 95

The wave profile shape and the spectral composition of a wave emitted into a medium by an oscillating spherically symmetrical surface are calculated. It is shown that the local distortions that occur upon the transition from the sphere vibrational motion to the medium wave motion are induced by the boundary nonlinearity.

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