R e g u l a r p a p e r s

Theoretical and mathematical physics

Moscow University Physics Bulletin 1990. **45**. N 1. P. 4

The photoneutrino process, $\gamma _{L,R} e^-_{L,R}\to e^- \nu \bar{\nu}$ due to interactions of the neutrino electromagnetic dipole moments ($\mu_{\nu}, d_{\nu}$) with an electron is examined. Expressions have been obtained for the total cross section of the process and for the photoneutrino luminosity of the Fermi electron gas.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 8

Radiative scattering of a relativistic spinless quantum particle by a constant magnetic flux of a thin solenoid is examined. The influence of the Aharonov-Bohm effect on circular polarization of radiation is analyzed.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 57bad

Solutions which describe the orbital evolution of ring particles for the first-order resonances have been obtained in terms of a restricted planar three-body problem where the central body is a symmetric spheroid.

Show AbstractRadiophysics

Moscow University Physics Bulletin 1990. **45**. N 1. P. 12

Consideration is given to the propagation of long-wave perturbations in a longitudinally uniform and magnetically insulated electron flow in a strip line. The speed of perturbation propagation has been found and the applicability limit of the results has been studied.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 18

A nonlinear theory of excitation of a broad electromagnetic helical wave spectrum by a hot electron beam in a finite magnetic field under conditions of anomalous Doppler effect is described. The instability stabilization mechanism has been elucidated. The results of numerical calculations and of analytical solutions are presented.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 24

A method based on superresolution algorithm is proposed for restoring signals in nonstationary noise with a frequency-dependent compression. The maximum attainable accuracy of restoration rises with increasing noise compression coefficient.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 28

The results of experimental investigation of the angular and energy distributions of secondary ions sputtered from aluminum polycrystals under argon ion bombardment are presented. Some conclusions have been drawn concerning the applicability of various sputtering and ion emission models.

Show AbstractOptics and spectroscopy

Moscow University Physics Bulletin 1990. **45**. N 1. P. 34

Taking into account perturbation of the wave number which corresponds to the "smearing" of the wave surface enables us to determine the waveguide mode of diffraction. The waveguide mode occurs when a perturbation overlaps the detunings.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 41

The effect of the Raman contribution to nonlinear susceptibility on the propagation of femtosecond optical solitons in lightguide fibers has been studied by numerical experimental methods. The results reveal the dependence of the self-frequency shift of a soliton pulse on the Raman scattering line parameters.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 46

The excitation spectra and the luminescence energy yield from non-activated and Eu- and Sm-activated BaFCl and BaFBr measured by the synchrotron radiation method are presented. The features of the light sum storage and emission by these phosphors and the effect of an excess of $BaF_2$ and the Fe, Co, Ni, Cu, and Pr impurities are discussed.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 51

This work develops a three-wave model of the saturation effect in nonstationary active Raman spectroscopy which allows for simultaneous scattering of a probing laser pulse in the Stokes and anti-Stokes regions. A formula has been obtained to estimate the Raman scattering cross section from measured parameters.

Show AbstractSolid state physics

Moscow University Physics Bulletin 1990. **45**. N 1. P. 65

Results of a photoemission study of radiation-induced defects on the NaCl crystal surface are presented. For the first time, data on photoemission from defects are interpreted on the basis of a model which takes into account the reflection and passage of an electron wave through the surface potential barrier of a solid.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 69

The magnetocaloric effect in tebrium-dysprosium alloys has been investigated. It is shown that the efficiency of employing rare-earth metals and their alloys in magnetic refrigerators depends on the range of existence of antiferromagnetic structures and the fields in which they are destroyed.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 73

The theorem of the catastrophe theory are used to show that all the phase transitions in the system with no more than three order parameters can phenornenologically be described by one of 15 classes of functions called min-functions.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 78

A theoretical analysis of the transmission factor of X-ray waveguides as a function of the waveguide length, bend radius, distance between the walls, and the beam divergence has been carried out for the case of total external reflection. The feasibility of deflection of X-ray beams by angles of up to 10-12° with an efficiency of about 10% has been demonstrated.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 83

Within the framework of the resonant model potential, expressions have been obtained for the form factor of a model Hamiltonian and the characteristic function of a transition metal. The expressions were used to calculate the energy band structure and phonon spectra of crystalline nickel, and the electrical resistivity of liquid nickel.

Show AbstractB r i e f r e p o r t s

Theoretical and mathematical physics

Moscow University Physics Bulletin 1990. **45**. N 1. P. 88bad

The general form of spherically symmetric solutions has been obtained for the relativistic gravitation theory. In terms of this theory, the spherically symmetric distributions of matter have been shown not to emit gravitational waves.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 91

The one-dimensional hydrogen atom (1H) model proposed by the present authors earlier [1, 2] is used to demonstrate that the probabilities of spontaneous transitions in 1H are of the same order as in three-dimensional hydrogen atom.The transitions have been shown to be in principle observable.

Show AbstractOptics and spectroscopy

Moscow University Physics Bulletin 1990. **45**. N 1. P. 94

A numerical method is described for solving the problem of obtaining an optical coatings with a prescribed transmittance in certain ranges of light wavelengths and incidence angles. Examples of synthesizing wide-band antireflection coatings designed for operation in the 0-45° range of light incidence angles are given.

Show AbstractSolid state physics

Moscow University Physics Bulletin 1990. **45**. N 1. P. 98

Irradiation by the UV light affects the semiconductor-metal transition in $VO_2$ films: changes are observed in resistance jump and transition temperature, and the hysteresis loop becomes wider.

Show AbstractMoscow University Physics Bulletin 1990. **45**. N 1. P. 101

The temperature dependence of the Hall mobility in a compensated semiconductor Ge<Au, Sb> exposed to infrared illumination and in the dark was studied at 5 K < T < 100 K. The effect of electric field on the Hall mobility at low temperatures was also investigated. The growth and saturation of the mobility during the infrared illumination at T < 8 К were shown to be due to a photostimulated heating of electrons; the ratio $\tau_{\epsilon}/\tau$ was evaluated.

Show AbstractGeophysics

Moscow University Physics Bulletin 1990. **45**. N 1. P. 105

The results of an experimental study of the possibility of adaptive focusing of laser radiation on a perturbed water surface are presented. The statistical criteria of the focusing are shown to be applicable to the problem of maximization of the radiant flux density on water surface.

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