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M.V.Lomonosov Moscow State University
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Theoretical and mathematical physics

## Quantization of lorentz-invariant systems in terms of Bogolyubov group variables. I: coordinate and linear-momentum operators

### S.Yu. Vernov, O.A. Khrustalev, M.V. Chichikina

Moscow University Physics Bulletin 2004. 59. N 1. P. 1

The Bogolyubov group is defined for $(N+1)$-dimensional systems invariant under transformations that form a Lie group, which makes it possible to carry out quantization near a time-dependent classical scalar field with allowance for conservation laws, and to solve the zero-mode problem.

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## Dirac equation in gauge field configurations modeling central vortices

### V.Ch. Zhukovskii, A.V. Skobeev

Moscow University Physics Bulletin 2004. 59. N 1. P. 6

Influence of central vortices on the spectrum of the Dirac operator eigenvalues is studied. To this end, fermion zero modes in the field of central vortices are found. A representation of the Dirac operator is constructed for a certain arbitrary vortex configuration in a subspace of linear combinations of zero modes of individual objects. Supersymmetry of the Dirac equation in these field configurations is demonstrated.

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## Numerical algorithm for calculation of supersonic flows based on quasi-gas dynamic equations

### T.G. Elizarova, M.E. Sokolova

Moscow University Physics Bulletin 2004. 59. N 1. P. 12

A new numerical algorithm for computation of gas supersonic flows based on the system of quasi-gas dynamic equations has been described and tested. A stationary problem about on axially symmetric flow around a cylinder and a nonstationary problem on a plane flow in a channel with a ledge has been considered. The results of computations demonstrate high precision and efficiency of the algorithm.

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## Heavy majorana neutrinos in dilepton production at lepton-proton colliders

### A.Ali, A.V. Borisov, D.V. Zhuridov

Moscow University Physics Bulletin 2004. 59. N 1. P. 19

Deep inelastic cross sections have been calculated for uniquely charged leptons pair production processes $e^+p\to \bar{\nu}_e\ell^+\ell'^+X$ and $\nu_ep\to e\ell^+\ell'^+X$ $(\ell, \ell' = e, \mu, \tau)$, caused by the exchange of heavy Majorana neutrinos. Possibilities of observation of these processes at the existing HERA ep-collider and at a designed supercollider VLHC have been discussed.

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## Perturbations in einstein's gravity theory: conserved currents

### A.N. Petrov

Moscow University Physics Bulletin 2004. 59. N 1. P. 24

General relativity in the form where gravitational perturbations together with other physical fields propagate against an auxiliary background has been considered. In an arbitrarily curved space—time, new conserved currents, i. е., divergences of skew-symmetric tensor densities (superpotentials) have been constructed with the use of the Katz—Bicak—Lynden-Bell technique.

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Atomic and nuclear physics

## Albedo flux generated in matter by particles with energy above 1 TeV

### D.M. Podorozhnyi, I.D. Rapoport, A.N. Turundaevskii

Moscow University Physics Bulletin 2004. 59. N 1. P. 29

Formation of back current of particles of hadronic cascades in dense matter is investigated. The energy dependence of the albedo flux, spatial and angular distributions of its different components are analyzed.

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## Reconstruction of energy spectrum and mass composition of primary cosmic rays from electron and muon number size spectra

### E.A. Vishnevskaya, V.N. Kalmykov, N.N. Kalmykov, G.V. Kulikov, V P. Sulakov

Moscow University Physics Bulletin 2004. 59. N 1. P. 35

The analysis of the experimental data from the ShAL MSU (ShAL is the Russian contraction for extensive air shower, or EAS, and MSU stands for Moscow State University) facility is used to estimate the mass composition of primary cosmic rays (PCR). The QGSJET quark-gluon model of hadronic interactions is used in the calculations, and it is assumed that the knee in the primary energy spectrum is the consequence of primary-cosmic-ray diffusion. The model used in the calculations provides a fairly good reproduction of the primary energy spectrum recorded at the ShAL MSU and ShAL Tunka-25 facilities. We also discuss the experimental spectra in the electron and muon numbers recorded at the KASCADE facility.

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## Transmutation of the $^{165}$Ho isotope in intensive $\gamma$-quanta flux

### B.S. Ishkhanov, I.A. Lyutikov, S.I. Pavlov

Moscow University Physics Bulletin 2004. 59. N 1. P. 41

Transmutation of the $^{165}$Ho isotope exposed to a $\gamma$-bremsstrahlung beam of flux intensity $\Phi=10^{17}$ photon $\cdot$c$^{-1}$ is considered. The effect on the transmutation chain formation of the short-lived $^{164}$Ho isotope resulting from the $\gamma-n$ reaction decaying along the $\beta^+,\beta^-$ channels with comparable intensities is analyzed.

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## Possibility of population inversion between nuclear levels

### A.V. Andreev, R.A. Chalykh

Moscow University Physics Bulletin 2004. 59. N 1. P. 45

The authors considered a possible technique of obtaining population inversion between the first excited state and the ground state of a Ge$^{73}$ nucleus based on selection of nuclei in the first excited state. The inversion dynamics were modeled and the effect of system parameters on population inversion were analyzed.

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## A scientific and educational complex for superhigh-energy cosmic ray research

### О.V. Vedeneev, G.K. Garipov, A.V. Igoshin, N.N. Kalmykov, G.V. Kulikov, V.I. Nazarov, M.I. Panasyuk, A.A. Silaev, A.A. Silaev Jr., V.P. Sulakov, Yu.A. Fomin, B.A. Khrenov, A.V. Shirokov

Moscow University Physics Bulletin 2004. 59. N 1. P. 50

A brief description of a scientific and educational complex for superhigh-energy cosmic ray research at the Research Institute of Nuclear Physics of Moscow State University that will be used to record extensive air showers (EAS) is given. The various scientific problems that can be solved with this complex are discussed.

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Optics and spectroscopy

## Estimating the size of a molecule by measuring time-domain coherent anti-stokes raman scattering

### S.Yu. Nikitin

Moscow University Physics Bulletin 2004. 59. N 1. P. 55

The correlation function of thermal velocity of molecules of a gaseous medium has been calculated in the rigid spheres model. It is shown that velocity correlation time is twice as long as the mean free path of a molecule. Estimates of the size of a hydrogen molecule have been made on the basis of the data on time-domain coherent anti-Stokes Raman scattering.

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Solid state physics

## Photoreflectance spectroscopy study of built-in electric fields in stressed GaAs/GaAsP superlattices

### L.P. Avakyants$^1$, P.Yu. Bokov$^1$, T.P. Kolmakova$^2$, A.V. Chervyakov$^1$

Moscow University Physics Bulletin 2004. 59. N 1. P. 60

The photoreflectance spectroscopy method has been used to study stressed GaAs/GaAs$_{0.6}$P$_{0.4}$ superlattices grown along the [100] and [111] directions. An analysis of the Franz-Keldysh oscillations observed in photoreflectance spectra determines the built-in fields in these superlattices. The fields amount to 80 kV cm$^{-1}$ for the (100) orientation and 430 kV cm$^{-1}$ for the (111) orientation. The difference has been explained by the presence of a strain-induced piezoelectric field in stressed superlattices grown along the [111] direction.

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Geophysics

## Hot plasma at the geostationary orbit. Some features of angular distributions of electron fluxes

### N.A. Vlasova, В.V. Mar'in, S.Ya. Reizman, I.A. Rubinshtein, E.N. Sosnovets, M.V. Tel'tsov

Moscow University Physics Bulletin 2004. 59. N 1. P. 65

Some features of the angular anisotropy of electron fluxes with an energy of about 0.1—14 keV as an instrument for studying hot plasma dynamics in the vicinity of the geostationary orbit have been investigated. The experimental data used in the study were obtained on March 11-25, 1992, at the GORIZONT-35 artificial earth satellite. It is shown that under the conditions of low geomagnetic activity electron fluxes in the vicinity of the geostationary orbit in the night sector of the magnetosphere are anisotropic, whereas at the time of geomagnetic disturbances they are almost isotropic.

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## Magnetomineralogical features of magnetite from different sedimentary rocks and deposits

### N.A. Sed'mov$^1$, V.F. Babanin$^1$, V.V. Morozov$^1$, A.A. Zalutskii$^1$, V.I. Trukhin$^2$, S.A. Shoba$^2$

Moscow University Physics Bulletin 2004. 59. N 1. P. 70

Magnetic fractions recovered from various types of soils and deposits have been studied by the methods of Mossbauer spectroscopy, magnetic measurements, X-ray diffractometry, scanning electron microscopy, and elemental microanalysis. The main component of the magnetic fractions was magnetite. Based on the shape of a Mossbauer spectrum, width and intensity of spectral lines, magnetomineralogical characteristics of natural magnetite have been identified and the degree of vacancies in its structure has been computed ($v=0.03\div 0.14$). It is shown that this parameter of magnetite depends on the redox environment in the formation medium.

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Solid state physics

## Effect of resonance mossbauer filter on the $^{125m}$Te isomer decay

### A.A. Opalenko, V.I. Vysotskii, A.A. Kornilova

Moscow University Physics Bulletin 2004. 59. N 1. P. 78

The curve of radioactive decay of the nucleus $^{125m}$Te surrounded by stable $^{125m}$Te nuclei, which constitute a resonance Mossbauer screen, has been measured. Thorough investigations have shown that the decay of a $^{125m}$Te nucleus follows the ordinary exponential law with a half-life of $T_{1/2}=58$ days without oscillations. The fact that oscillations are present in the curves of radioactive decay of the long-lived isomer $^{125m}$Te, which has a Mossbauer level, is the result of measurement errors associated with the method.

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