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

## Neutrino-pair emission by nonrelativistic neutrons in the field of a circularly polarized plane wave

### V.V. Skobelev, I.F. Botsiev

Moscow University Physics Bulletin 1987. 42. N 4. P. 1

Neutrino-pair creation by a nonrelativistic neutron in the field of a circularly polarized plane electromagnetic wave is considered. An expression is obtained for the total probability of the process as a function of the frequency of the incident wave and the anomalous magnetic moment of the neutron.

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## Spinning fluid in gage theory of gravitation

### V.A. Korotkii, Yu.N. Obukhov

Moscow University Physics Bulletin 1987. 42. N 4. P. 6

A systematic theory of a fluid with spin is developed on the basis of a first-order variational principle. The proposed theory is appropriate not only for Einstein-Cartan theory but also in a wider class of gage theories in which the gravitational Lagrangian includes terms that are quadratic in the torsion and curvature.

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## Lepton contribution to the polarization operator of the W boson in a constant magnetic field

### A.V. Borisov, V.Ch. Zhukovskii, M.Yu. Knizhnikov, A.N. Prokopenya

Moscow University Physics Bulletin 1987. 42. N 4. P. 12

The lepton contribution to the polarizational operator of a W boson in a constant homogeneous magnetic field is calculated in a single-loop approximation. Various limiting cases are investigated. The lepton contribution to the anomalous magnetic moment of the W boson is singled out from the expansion of the expression for the polarization operator in a weak field.

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Atomic and nuclear physics

## Photofission of nuclei of the ld2s shell

### N.A. Bogdanova, A.N. Gol'tsov, V.S. Ishkhanov, V.N. Orlin

Moscow University Physics Bulletin 1987. 42. N 4. P. 18

The results of photofission of $^{24}Mg$, $^{26}Mg$, $^{28}Si$, and $^{32}S$ nuclei within the framework of the semimicroscopic vibration model are discussed. It is shown that configurational splitting of the dipole giant resonance (DGR) is observed for all these nuclei. Including states corresponding to transitions from partially filled levels in the particlehole basis allows the basic structural features of the experimental photoabsorption cross sections to be explained. The role of isospin DGR fission is studied for the $^{26}Mg$ nucleus.

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Optics and spectroscopy

## Adaptive optical system with systematic probing

### M.A. Vorontsov, I.A. Kudryashov

Moscow University Physics Bulletin 1987. 42. N 4. P. 26

A model of an adaptive optical system of aperture probing with systematic introduction of variation in the phase of the light wave is investigated. The system has three control loops and permits stabilization of the position of the coherent light beam in space (two control loops) and automatic focusing of this beam.

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## Parametric difference-frequency generation in the field of a multimode pumping wave

### V.A. Aleshkevich, V.Ya. Gaivoronskii, A.N. Matveev, V.A. Trofimov

Moscow University Physics Bulletin 1987. 42. N 4. P. 32

Parametric generation in the field of a multimode pumping wave is investigated numerically and analytically, in the case when diffractional effects are significant. The dependence of the efficiency of energy transformation and the degree of coherence of the wave generated on the number of spatial inhomogeneities of the pumping beam is analyzed. It is shown that, in conditions of strong energy transfer, conditions of self-channeling of the individual inhomogeneities set in, and the efficiency of the process at the length of diffractional reduction of the phases is practically independent of the initial mode composition of the pumping wave.

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Acoustics and molecular physics

## Sound-wave propagation in acoustooptical crystals of paratellurite and calomel

### M.A. Voronova, V.N. Parygin

Moscow University Physics Bulletin 1987. 42. N 4. P. 38

The acoustic field of a slow quasi-shear wave created by a plane converter with a Gaussian aperture function close to the crystallographic direction [110] is investigated for paratellurite and calomel crystals. The parabolic approximation of the wave-vector surface is used. The dependence of the parabolic-approximation coefficients on the wave-vector direction is given. The limits of parabolicity are given. The method of calculating the geometry of the acoustic beam excited along the axis [110] is considered.

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## Pressure pulsations at the surface of a sphere in a fluid flow

### F.V. Rozhin, O.S. Tonakanov, S.G. Mikhailov

Moscow University Physics Bulletin 1987. 42. N 4. P. 45

Experimental results are given for the distribution of pressure pulsations as a function of the angle between the direction of the fluid flow and the position of pulsation detection by a small sensitive element. Angular and spectral characteristics of the pressure pulsations are obtained at small flow velocities (0.25 and 0.5 m/sec). It is shown that the maximum pulsations are obtained in the "dark" part of the sphere in the turbulized flow region.

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Biophysics

## Slow induction of fluorescence in leaves of higher plants grown in various light conditions and also in the presence of chemical agents (antimycin A and $NH_4Cl$)

### I.O. Belogrudov, V.A. Karavaev, A.K. Kukushkin

Moscow University Physics Bulletin 1987. 42. N 4. P. 50

Variation in the parameters of slow induction of fluorescence is studied as a function of the light intensity during growth. The relation between the inductional transitions of fluorescence and the functional activity of the photosynthetic apparatus is shown. The action of chemical agents (antimycin A and $NH_4Cl$) on the kinetics of slow induction of fluorescence is also studied.

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Solid state physics

## Laser nickel plating of semiconductors

### A.A. Eremenko, V.V. Zadde, A.K. Zaitseva, E.K. Kozlova, A.I. Portnyagin, A.N. Romanchenko, A.E. Filippov

Moscow University Physics Bulletin 1987. 42. N 4. P. 57

The action of laser radiation on the semiconductor-electrolyte system leads to acceleration of the reduction of nickel and/or ordering of the residue structure. The mechanism of increase in the deposition rate is associated with a set of thermal and electrical influences of laser radiation on the given system.

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## Ternary superstructure in alloys of the quasi-binary system $Ho(Fe_{1-x}Mn_x)_2$

### A.S. Ilyushin

Moscow University Physics Bulletin 1987. 42. N 4. P. 62

The nuclear gamma-resonance method is used to study the local distribution of atoms in the 3d sublattice of intermetallides in the quasibinary system $Ho(Fe_{1-x}Mn_x)_2$ and a ternary superstructure of stoichiometry $Ho(Fe_{0,25}Mn_{0,75})_2$ is observed.

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## Development of contactless ultrasonic methods of investigating solids

### A.N. Vasil'ev

Moscow University Physics Bulletin 1987. 42. N 4. P. 67

Utilizing the direct transformation of electromagnetic and acoustic waves in conducting media offers the possibility of a fundamentally new approach to the formulation of the ultrasound experiment. Contactless methods that have been based on this phenomenon for changing the velocity and damping of ultrasound in metals and semiconductors are described.

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## Mechanism of current transfer in surface-barrier structures p-Si/polymer material/$SnO_2$

### V.E. Senyuk, G.G. Untila, A.L. Kharitonov, L.B. Rubin

Moscow University Physics Bulletin 1987. 42. N 4. P. 74

The temperature dependence of the volt-ampere characteristics of photoelectric converters (PEC) p-Si/polymer material/$SnO_2$ is investigated for samples with different levels of silicon doping. The relation is established between the mechanism of current-carrier transport and the no-load potential $V_{хх}$. It is shown that the reduction in $V_{хх}$ with increase in the level of silicon doping may be associated with increase in the PEC dark current on account of the multistage-tunneling mechanism.

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## Thermoemf in relaxational conditions

### Yu.P. Drozhzhov

Moscow University Physics Bulletin 1987. 42. N 4. P. 80

A relaxational semiconductor with an injective contact is considered. It is shown that a term that is activationally dependent on the temperature may appear in the expression for the thermoemf of the sample, in the given conditions.

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## Electron structure of beryllium oxide

### I.V. Kityk, V.N. Kolobanov, V.V. Mikhailin

Moscow University Physics Bulletin 1987. 42. N 4. P. 84

A quantitative scheme of the energy band structure is constructed by the pseudopotential method, with correction with respect to the experimental reflection spectrum of a chip of BeO single crystal in the fundamental region of the spectrum. The results are compared with known theoretical and experimental data.

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Geophysics

## Determining the spectral parameters of marine waves

### A.L. Kuz'minskii, V.I. Shmal'gauzen

Moscow University Physics Bulletin 1987. 42. N 4. P. 90

A development of the well-known method of laser probing of the marine surface is proposed. The method developed for analyzing the map of flashing points allows the Phillips spectral parameters to be derived from six independent measurements.

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## Degree of intensity of atmospheric eddies

### A.A. Solov'ev

Moscow University Physics Bulletin 1987. 42. N 4. P. 96

The problem of the relation between the pressure and wind-velocity fields in atmospheric eddies is solved. On the basis of comparison of the data of full-scale and laboratory experiments, it is proposed that a parameter relating the pressure minimum and the maximum of the surface-wind velocity be used to estimate the intensity of the eddies.

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Astronomy

## Spectrum of small-scale magnetic structures in the Sun

### N.N. Kantor

Moscow University Physics Bulletin 1987. 42. N 4. P. 101

Data on the mean parameters and the number of local magnetic structures (LMS) at the Sun, such as active regions, ephemeral regions, magnetic points, and magnetic elements, do not contradict the concept that the whole set of LMS is described, in a rough approximation, by a single power-law spectrum.

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## Quantum interferometer in regenerated conditions at a gravitational antenna

### A.V. Gusev

Moscow University Physics Bulletin 1987. 42. N 4. P. 107

The limiting sensitivity of a solid-state gravitational antenna with a recording element based on a radiofrequency squid is theoretically investigated, choosing a working point between adjacent plateaus. Formulas are obtained for estimating the minimum observable force determined by the thermal noise of the contact, the thermal noise of the contour, and the nonthermodynamic fluctuations of the preamplifier, with amplitude demodulation of the squid output signal. The optimal magnetomechanical coupling.coefficient is determined as a function of the parameter $g$.

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## Theory of autodyne spin generator

### Yu.S. Konstantinov

Moscow University Physics Bulletin 1987. 42. N 4. P. 110

The theory of an autodyne spin generator (ASG), which is a spin generator on the side. band with modulation of the HF field, is given. In its construction, the ASG consists of a nonisochronous audyne sensor of NMR signals with a working sample in the coil of an oscillatory loop. It is shown that excitation of spin generation becomes possible as a result of mixed amplitude-frequency modulation of the autodyne oscillations, ensuring satisfaction of the condition of phase balance at near-Larmor frequencies.

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Theoretical and mathematical physics

## Beam-plasma interaction in conditions of the Cherenkov collective effect

### A.F. Aleksandrov, M.V. Kuzelev, A.N. Khalilo

Moscow University Physics Bulletin 1987. 42. N 4. P. 113

An analytical solution is given for the problem of the interaction of "thin" completely magnetized plasma and an electron beam in conditions of the collective Cherenkov effect. The saturation mechanism of the beam-plasma instability in the given conditions is elucidated.

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Optics and spectroscopy

## Mode synchronization in a continuous dye laser with a nonsteady resonator

### A.S. Abubakirov, N.V. Kravtsov, V.P. Protasov, V.A. Sidorov

Moscow University Physics Bulletin 1987. 42. N 4. P. 117

The results of investigating a continuous jet laser based on Rhodamine 6G with a nonsteady resonator are presented. The possibility, in principle, of realizing conditions of kinematic mode stabilization is demonstrated. The basic laws determining the features of supershortpulse generation in this laser in comparison with lasers of other types are established.

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Solid state physics

## Magnetic and M$\stackrel{..}{o}$ssbauer investigations of new antiferromagnetic compounds of $RFeGe_2O_7(R=La-Gd)$

### B.V. Mill, Z.A. Kazei, S.I. Reiman, S.A. Ramazyan, F.D. Khamdamov, L.Yu. Bykova

Moscow University Physics Bulletin 1987. 42. N 4. P. 121

Compounds $RFeGe_2O_7$ containing two kinds of magnetic ions - $Fe^{3+}$ and $R^{3+}$ (R = La-Gd) - are synthesized for the first time. The M$\stackrel{..}{o}$ssbauer spectra of $^{57}Fe^{3+}$ are measured, together with its magnetic and elastic properties; antiferromagnetic ordering at temperatures 5-9 K is observed. The ordering temperatures, paramagnetic temperatures, and superfine fields at $^{57}Fe^{3+}$ nuclei are determined. It is concluded that the $R^{3+}—Fe^{3+}$ interaction in these compounds is comparable with the $Fe^{3+}—Fe^{3+}$ interaction, and makes a significant contribution to the magnetic and elastic properties.

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## Influence of $\gamma$ radiation on the specific heat and spontaneous polarization of diglycerine-nitrate crystals

### B.A. Strukov, Z.V. Savilova, S.A. Taraskin

Moscow University Physics Bulletin 1987. 42. N 4. P. 126

The thermal and dielectric properties of $\gamma$-irradiated diglycerine-nitrate crystals are investigated at radiation doses of 1-30 MR. The data obtained are discussed in the context of the most probable type of radiation defects.

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## Microhomogeneity of amorphous structure in the alloy $Cu_{35}Zr_{65}$

### G.S. Zhdanov, N.A. Khatanova, A.R. Altynbaeva

Moscow University Physics Bulletin 1987. 42. N 4. P. 130

It is established by means of X-ray diffraction analysis and diffractional electron microscopy, that the amorphous alloy $Cu_{35}Zr_{65}$ undergoes natural aging. After holding at room temperature for three years, partial crystallization of $CuZr_2$ phase occurs. It is shown that both topological and compositional short-range microheterogeneity is observed in the amorphous phase remaining after partial crystallization.

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