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

## Finslerian $g$-correction of relativistic dynamic relations

### G.S. Asanov

Moscow University Physics Bulletin 1998. 53. N 5. P. 1

The method of calculating the Finslerian corrections to basic dynamic relations has been proposed. The approach encompasses transitions among the laboratory reference frame, the center-of-mass frame, and the target reference frame.

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## Positronium atoms production in light mesons decays

### A.P. Martynenko$^1$, R.N. Faustov$^2$

Moscow University Physics Bulletin 1998. 53. N 5. P. 6

Orthopositronium production rate in the $\pi^0$-meson decay has been studied in the framework of the quasipotential method of bound state description. Relativistic and radiative corrections of the order $O(\alpha)$ to the decay width have been calculated, and their comparison with the experimental data has been carried out.

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## Mathematical substantiation of variational-difference approach to numerical modeling of waveguide systems

### A.N. Bogolyubov, A.L. Delitsyn, I.E. Mogilevskii

Moscow University Physics Bulletin 1998. 53. N 5. P. 12

Studies on the convergence of the finite element method for waveguide problems are surveyed.

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## On bremsstrahlung of photons in electron scattering from nuclei

### A.I. El-Gauhari

Moscow University Physics Bulletin 1998. 53. N 5. P. 18

A general expression has been obtained for the differential cross section of the bremsstrahlung process in electromagnetic scattering of unpolarized electrons from polarized nuclei with arbitrary spin accounting for circular polarization of $\gamma$-quanta. Consideration for the nucleus polarization in these processes opens up fresh opportunities for individual investigation of nuclear multipoles.

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## Morphological method of adaptive correction of image sensor array elements

### Yu.P. Pyt'ev, S.S. Zadorozhny

Moscow University Physics Bulletin 1998. 53. N 5. P. 23

Morphological image analysis is used for sensor adaptive correction without any special testing in the process of actual image interpretation.

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## Intrinsic geometry of surfaces and spectra-evolutionary problem statement

Moscow University Physics Bulletin 1998. 53. N 5. P. 29

The construction of spectra-evolutionary operators of the inverse scattering problem by the differentional geometry methods is proposed. The algorithm discussed follows the analogy between the surface structure equations in $E^3$ and the formalism of the inverse scattering problem method.

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## Absorption of a high-power electromagnetic pulse of short duration by a dense plasma layer

### L.V. Borodachev, P.A. Gofman

Moscow University Physics Bulletin 1998. 53. N 5. P. 34

The numerical experiment method has been employed in the study of a collision-free regime of interaction of an ultra-short high-power laser pulse with a surface plasma layer of a condensed target. The use was made of the $(1\frac22)$-dimensional discrete kinetic model of a nonrelativistic plasma with an ion background in the Darwin approximation for self-consistent electromagnetic fields. The behavior of the skin layer plasma has been found to differ substantially from the linear theory predictions. The average value of energy of electrons is comparable with their oscillation energy. The particles distribution function is highly anisotropic and differs significantly from the Maxwellian distribution.

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Optics and spectroscopy

## Three-wave mixing in stationary parametric holographic scattering: exact solution with depleted pumping

### P.A. Prudkovskii, O.V. Skugarevskii, A.N. Penin

Moscow University Physics Bulletin 1998. 53. N 5. P. 43

A three-wave model of parametric holographic scattering has been discussed. It is demonstrated that, under the assumption of scattering symmetry, an exact stationary solution with regard to depleted pumping can be obtained. The solution dependence on the initial phase difference of the three waves has been analyzed. An idea of certain experiments has been proposed for obtaining new information on photorefractive crystal parameters and the nature of seed radiation.

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Acoustics and molecular physics

## Conditions of Boussinesq approximation applicability to the analysis of stationary medium convective stability

### A.V. Uvarov, A.I. Osipov

Moscow University Physics Bulletin 1998. 53. N 5. P. 49

Analysis of a complete system of hydrodynamic equations that made it possible to obtain the applicability conditions of the Boussinesq approximation in the vicinity of the convective stability loss critical conditions has been carried out. It has been demonstrated that an intricate system of inequalities reduces to simple criteria determined mainly by the system characteristic dimensions. The criteria found in the literature that involve an unjustified narrowing of the field of the Boussinesq approximation application have been analyzed. The found criteria have been used for estimating the parameters of real systems, where the Boussinesq approximation holds.

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## Translational nonequilibrium in shock wave front in argon

### P.V. Kozlov, S.A. Losev, Yu.V. Romanenko

Moscow University Physics Bulletin 1998. 53. N 5. P. 55

We have studied the influence of a non-Maxwellian velocity distribution of gas particles in the front of a shock wave on the mechanism of gas excitation and emission. Shock wave emission in a H$_2$:Ar mixture with a 1:99 concentration ratio has been studied experimentally at M=6 and a mechanism has been proposed for this emission. It is shown that the emission in these conditions is purely nonequilibrium. The importance of consideration of the non-Maxwellian distribution in the course of exothermal reactions in a gas has been emphasized.

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Solid state physics

## Structural features of Al, Ti, Pd, and Ta films obtained in discharge with oscillating electrons

### V.V. Bibikova, E.V. Likhushina, S.V. Sveshnikov, G.V. Smirnitskaya

Moscow University Physics Bulletin 1998. 53. N 5. P. 62

The structure of thin AI, Ti, Pd, and Ta films deposited on glass substrates in discharge with oscillating electrons in two discharge modes (different pressures and discharge currents) has been studied. Deposition and particle flow rates have been determined. The content of Kr in the films was found to be of the order of several tenths of percent. The structure studies have shown that the films had a pronounced texture; the diffraction pattern distorted in some directions was evidence of packing defects. The structure of light metal (Al and Ti) films was shown to depend on discharge conditions; no such dependence was observed for heavy metals (Pd and Ta). All films prepared in mode II were less defective than films prepared in mode I.

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## Strong localization of current carriers in multilayer InAs/GaAs structures with quantum dots

### V.A. Kul'bachinskii, V.G. Kytin, R.A. Lunin, A.V. Golikov, A.V. Demin, I.G. Malkina, B.N. Zvonkov, Yu.N. Saf'yanov

Moscow University Physics Bulletin 1998. 53. N 5. P. 65

The transport and optical properties of $p$- and $n$-type lnAs/GaAs multilayer structures with quantum dots have been studied depending on the amount of deposited InAs. Indium arsenide quantum dots in GaAs have been found to form two-dimensional electronic or hole layers generating Shubnikov-de Haas oscillations. The experimental temperature dependences of resistance in the $[110]$ and $[\bar{1}10]$ directions (the temperature range of 1.6-300 K) have shown the resistance to be anisotropic. Experiment evidences that electric current carriers become localized as temperature decreases. According to the photoluminescence spectral data, light emitted in the plane of the structure is polarized.

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## A M$\stackrel{..}{o}$ssbauer study of atomic distribution in alloys $\beta$-Mn$_{18}$Sn$_{2-x}$Fe$_x$

### V.S. Rusakov, A.S. Ilyushin, A.S. Vinogradova, I.A. Nikanorova

Moscow University Physics Bulletin 1998. 53. N 5. P. 71

The atomic distribution in $\beta$-Mn$_{18}$Sn$_{2-x}$Fe$_x$ ($x=0\div2$) alloys has been studied by the $^{57}$Fe M$\stackrel{..}{o}$ssbauer spectroscopy. The earlier suggestion that the $8(c)$ sites in the $\beta$-Mn structure are favoured by iron atoms has been substantiated. Annealing was found to increase the degree of long-range order in the arrangement of iron atoms with respect to the $8(c)$ sites in the $\beta$-Mn structure. The presence of tin atoms in the $\beta$-Mn structure had virtually no effect on the degree of long-range order or iron atoms.

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Atomic and nuclear physics

## Correlation between variations in the flux of galactic cosmic rays and variations in solar activity factors and interplanetary medium parameters during minima of even cycles of solar activity

### S.N. Kuznetsov, I.N. Myagkova

Moscow University Physics Bulletin 1998. 53. N 5. P. 77

The correlation between the fluxes of galactic cosmic rays (GCR) and the number of solar spots decreased during the minima of the last two even solar activity cycles, but persistent correlation existed between the GCR fluxes and the modulus of the Sun's magnetic field and the solar wind velocity, which is probably associated with a decisive influence of the high-speed solar wind that flows from polar coronal holes on the properties of the interplanetary medium in these periods.

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## Autoionization state characteristics of atoms interacting in a strong electromagnetic field

### A.I. Magunov, S.I. Strakhova

Moscow University Physics Bulletin 1998. 53. N 5. P. 82

The spectra of photoabsorption of a trial electromagnetic radiation by a magnesium atom in the vicinity of the $3p^2\ ^1S$ autoionization state { AIS) have been calculated in the resonance approximation. The $3p{^2\ ^1}S$ AIS is connected with the $3p3d\ ^1P$ state by a strong laser field. A qualitative agreement has been obtained with the measured ion yield in two-photon ionization of magnesium vapors by bichromatic laser radiation for various laser frequency values.

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Optics and spectroscopy

## Scanning microscopy, speckles, and Gabor's information diagram

### Yu.V. Vasil'ev, E.F. Kuritsyna, A.E. Luk'yanov

Moscow University Physics Bulletin 1998. 53. N 5. P. 86

An information approach has been proposed for solving the task of express quality analysis of cutting tools using advanced, mutually complementary experimental techniques: the scanning microscopy and the optics of speckles.

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Solid state physics

## Investigation of hydrated DNA molecular mobility

### A.A. Opalenko, O.G. Shirmin, M.A. Opalenko

Moscow University Physics Bulletin 1998. 53. N 5. P. 89

It has been obtained experimentally that the dynamic characteristics of water and some DNA components are additive. The M$\stackrel{..}{o}$ssbauer parameters $f_R$ and ${<}u^2{>}$ have been found for the "spiral-tangle" transition that accompanies DNA denaturation.

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