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

## Axion emission by electrons scattered by fiuxoids in a superconducting core of a neutron star

### A.V. Borisov, P.E. Sizin

Moscow University Physics Bulletin 2000. 55. N 4. P. 1

Axion bremsstrahlung by electrons scattered in a magnetic field of Abrikosov strings (fluxoids) with a single quantum of magnetic flux is considered. The axion luminosity of a highly degenerate relativistic electron gas caused by the above process taking place in the superconducting core of a neutron star is calculated. By comparing this luminosity with that caused by neutrino pair bremsstrahlung in electron scattering by fluxoids, restriction on the axion-electron coupling constant is obtained.

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## Fragmentation of polyatomic organic molecules on the surface under the action of low-energy ions

### V.V. Komarov$^1$, A.M. Popova$^1$, I.O. Stureiko$^1$, H. Jungclas$^2$

Moscow University Physics Bulletin 2000. 55. N 4. P. 5

A model of the excitation of collective vibrational states (excimoles) in molecular chains of ordered valence groups of the C-F and C-H types (contained in thin organic films) under the action of sliding ions whose velocity is less than the Bohr velocity is proposed. The probabilities of accumulation of several excimoles and fragmentation of molecular chains in relation to the velocity of initial ions and the structure of molecules are analyzed.

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## Binary primordial black holes as sources of gamma-ray-bursts and high-frequency gravitational radiation

### D.N. Abdurashitov, K.V. Parfenov, V.E. Yants

Moscow University Physics Bulletin 2000. 55. N 4. P. 10

If supercompact binary systems formed by primordial black holes (PBH} with masses $m>10^{16}$ g constitute the major part of the dark matter in the Universe, then the high frequency diffuse gravitational radiation with the flux of the order of 1 erg$\cdot$см$^{-2}\cdot$с$^{-1}$ should be expected. A possibility that a part of the gammaray-bursts observed is a consequence of coalescence of binary PBH in the Galaxy halo limits is discussed. It is pointed out that these systems can be detected when high-frequency ($\omega>10^4$ Hz) gravitational radiation is recorded.

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## Threshold sensitivity of a stroboscopic coordinate meter

### N.V. Kozlov, F.Ya. Khalili

Moscow University Physics Bulletin 2000. 55. N 4. P. 15

Exact expressions for a threshold sensitivity of a stroboscopic coordinate meter have been obtained. A particular case of application of a small-displacement modulating transducer is considered.

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## Application of the GCV method to well- and ill-posed problems

### V.N. Titarenko, A.G. Yagola

Moscow University Physics Bulletin 2000. 55. N 4. P. 21

On an example of systems of linear algebraic equations, it is shown that the algorithm for solving ill-posed problems based on the GCV method is not regularizing in the general case.

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## Structure of the photon polarization operator in an external nonuniform non-Abelian gauge field

### V.Ch. Zhukovskii, V.V. Khudyakov

Moscow University Physics Bulletin 2000. 55. N 4. P. 26

The photon polarization operator (PO) in an external constant chromomagnetic field is considered. For the case of a weak uniform external field, the one-loop scalar and spinor quark contributions to its antisymmetric component as well as an induced topological photon mass are obtained. Using the instanton field as an example, the P0 in the nonuniform external field case is considered.

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Atomic and nuclear physics

## Competition of photoneutron and photoproton channels in photodisintegration of atomic nuclei

### S.S. Borodina, B.S. Ishkhanov, V.I. Mokeev, S.I. Pavlov

Moscow University Physics Bulletin 2000. 55. N 4. P. 31

A model for describing the ratios of integrated cross sections of the $(\gamma, Xn)$ and $(\gamma,p)$ reactions for $10<A<150$ nuclei is presented. The model is based on a phenom.enological parametrization of the main formation and decay mechanisms of giant dipole resonance using all available experimental data in the $10<E_{\gamma}<30$ MeV energy range. Within the measurement accuracy of about $(\sim30\%)$ the ratios of experimentally measured integrated cross sections of the $(\gamma, Xn)$ and $(\gamma, p)$ reactions are reproduced.

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## TwO-:particle quantum system: self-consistent field approximation and particle-to-particle correlations

### D.V. Kulakovskii, A.M. Popov

Moscow University Physics Bulletin 2000. 55. N 4. P. 35

Taking a model two-particle system as an example, the accuracy of determining the energy spectrum and wave functions of steady states within the Hartree-Fock self-consistent field approximation is studied. The possibility of using this approximation to describe particle-to~particle correlations is discussed.

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## Anomalous asymptotics of the overlap integral for bound systems of three or more bodies

### L.D. Blokhintsev$^1$, 0. Dias$^1$, D.Kh. Muminova$^2$, R. Yarmukhamedov$^2$

Moscow University Physics Bulletin 2000. 55. N 4. P. 46

Explicit expressions for an anomalous asymptotic form of the overlap integral of wave functions for systems $a$, $b$, and $c$ corresponding to virtual decay $a\to b+c$ with account of particle spins and nonzero orbital angular momenta have been obtained. Specific examples of nuclear systems with anomalous asymptotics that are of interest for astrophysics are considered.

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Optics and spectroscopy

## A method for rapidly estimating the thickness of nanometer film targets and its application in experiments on generation of picosecond X-ray pulses

### V.M. Gordienko, A.B. Savel'ev, A.A. Shashkov

Moscow University Physics Bulletin 2000. 55. N 4. P. 51

A method for rapidly determining the thickness of nanometer dielectric films accurate to $\pm$2-3 nm is suggested. The method is a modification of the ellipsometric method and is based on Brewster angle measurements for light passing through film-substrate systems. The results are used in experiments on effective generation of soft X-rays in dangling superthin films exposed to $10^{16}$ W /cm$^2$ laser pulses.

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## An adaptive system with a shearing interferometer in an optical feedback circuit

### P.V. Ivanov, A.V. Koryabin, V.I. Shmal'gauzen

Moscow University Physics Bulletin 2000. 55. N 4. P. 57

The results of linear analysis, numerical modeling, and experimental study of an adaptive optical system with a liquid-crystal phase modulator and a shearing interferometer in a feedback path are presented. The results of experiments on compensation of small-scale phase distortions agree well with theoretical and numerical estimates.

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Solid state physics

## Interpreting the anomalous growth of co~rcive force and magnetic viscosity in ferrites near the Curie point

### K.P. Belov

Moscow University Physics Bulletin 2000. 55. N 4. P. 63

The concept of unidirectional exchange anisotropy is used to explain anomalous growth of coercive force and magnetostatic viscosity near the Curie point. The phenomenon was observed for several ferrites but has not received correct interpretation as yet.

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Geophysics

## The possibility of earthquake prediction by a polarimetric method

### V.I. Grigor'ev, V.S. Rostovskii

Moscow University Physics Bulletin 2000. 55. N 4. P. 68

A fundamentally new method for earthquake prediction based on polarimetric studies is discussed.

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Theoretical and mathematical physics

## Angular distribution of neutral particle radiation in electromagnetic field

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

Moscow University Physics Bulletin 2000. 55. N 4. P. 72

Angular distribution of radiation of an unpolarized neutral particle with an anomalous magnetic moment has been found in a classical approximation on its motion in an arbitrary electromagnetic field. The result has been obtained on the assumption that the particle spin evolution is defined by the BargmannMichel- Telegdi equation.

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## Integrals of motion of the Calogero-Sutherland quantum system in an external field

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

Moscow University Physics Bulletin 2000. 55. N 4. P. 75

The three-particle Calogero-Sutherland system in an external field is considered. A procedure for ordering the noncommuting variables in the integrals of motion is suggested. The integrals of motion in explicit form are found.

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Optics and spectroscopy

## Two-stream high-frequency instability in atomic media

### V.K. Grishin

Moscow University Physics Bulletin 2000. 55. N 4. P. 78

It is shown that streams of fast atoms or compound ions may be unstable due to anomalous Doppler transitions at slow waves in a neutral gas and serve as a source of induced high-frequency radiation. Possible parameters of such physical systems are estimated.

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Geophysics

## The mechanism of transformation of ocean stratification structure by seismic floor motions

### M.A. Nosov, S.N. Skachko

Moscow University Physics Bulletin 2000. 55. N 4. P. 81

A possible physical mechanism that can help transportation of deep waters to the ocean surface in the case of a submarine earthquake is shown to be formation of a nonlinear flow generated by fluctuations of part of the ocean floor.

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Astronomy

## Motion of a spacecraft equipped with a current-carrying rod on polar orbit in the Earth's gravitational and magnetic fields

### V.I. Denisov, V.B. Pinchuk

Moscow University Physics Bulletin 2000. 55. N 4. P. 85

An exact solution to nonlinear equations describing the spacecraft motion under the action of Ampere forces and gravitational forces under a partial law of current-carrying element control is found.

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