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Theoretical and mathematical physics

A property of second-rank tensors and fourth-order matrices

A property of second-rank tensors and fourth-order matrices

V.I. Denisov

Moscow University Physics Bulletin 1985. 40. N 5. P. 1

It is shown that the product of any number N of identical fourth-order matrices $\Lambda$ can always be represented as a linear combination of four independent powers of this matrix: $(\Lambda)^0 = I$ , $\Lambda$, $(\Lambda)^2$, and $(\Lambda)^3$. An analogous feature is established for the N-th degree of a second-rank tensor, i.e., a tensor constructed from N tensors $\phi_n{}^i(x)$ all of whose indices are sequentially convoluted, apart from the contravariant index to the first tensor and the covariant one for the last.

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Polarization effects in the decay of a massive neutrino in an external field

Polarization effects in the decay of a massive neutrino in an external field

M.Yu. Knizhnikov, A.N. Prokopenya

Moscow University Physics Bulletin 1985. 40. N 5. P. 6

Calculations have been made on the probability of a massive neutrino decaying to a pair of W bosons and then electron in a steady external magnetic field. The exact wave functions for the electron and a W boson in a magnetic field are used. An expression is obtained for the decay probability as a function of the electron's polarization. The asymptotes of this expression are considered.

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Motion of an electron in the field of a standing electromagnetic wave

Motion of an electron in the field of a standing electromagnetic wave

A.M. Khapaev, I.V. Ponomarev

Moscow University Physics Bulletin 1985. 40. N 5. P. 11

The classical equations of motion are analyzed for a relativistic electron in the superposition of a standing wave and a steady magnetic field, which gives an integral of motion relating the energy to the radius of the cyclotron orbit. The cases of finite and infinite motion are examined. The quantum approach is based on solving the Klein-Gordon equation and is supplemented by analysis of the energy spectrum as affected by the type of boundary conditions.

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Spectrum and angular distribution of coherent synchrotron radiation

Spectrum and angular distribution of coherent synchrotron radiation

N.P. Klepikov, A.K. Yashchenko

Moscow University Physics Bulletin 1985. 40. N 5. P. 16

The spectral and angular intensity distribution have been obtained for the joint emission from a system of electrons moving over similar circles, and an approximate expression is derived for the total emission intensity.

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Transitional scattering at a charged filament of spiral or sinusoidal form

Transitional scattering at a charged filament of spiral or sinusoidal form

V.V. Kolesov

Moscow University Physics Bulletin 1985. 40. N 5. P. 19

Transitional scattering is considered for a dielectric-permittivity wave at a charged filament having the form of a spiral line or sinusoid. Perturbation methods give expressions for the spectrum and the angular distribution. The polarization of the radiated electromagnetic waves has been examined. The emission spectrum is analyzed.

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Atomic and nuclear physics

Nuclear neutrino scattering and the structure of the weak neutral hadron current

Nuclear neutrino scattering and the structure of the weak neutral hadron current

A.Z. Agalarov, В.K. Kerimov, A.M. Mourao (Portugal)

Moscow University Physics Bulletin 1985. 40. N 5. P. 23

Cross sections have been calculated for neutrino (antineutrino) scattering at nuclei $\bar{\nu}(\nu)A_i\to \nu(\bar{\nu})A_f$ due to neutral-current interact ion. A study is made of the neutrino excitation of isoscalar transitions in $^{12}С(0^+0\to 1^+0)$ and $^{14}N (1^+0\to 2^+0)$, which is sensitively dependent on the isoscalar component of the weak neutral hadron axial current. When the latter is present, the total neutral hadron axial current. When the latter is present, the total cross sections for neutrino and antineutrino excitation of the isoscalar transition in $^{14}N$ show considerable differences in relation to the energy $E_{\nu}$ of the neutrino (antineutrino).

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Final-state interaction in deuteron electrodisintegration: a relativistic approach

Final-state interaction in deuteron electrodisintegration: a relativistic approach

V.V. Komarov, A.P. Trishchenko

Moscow University Physics Bulletin 1985. 40. N 5. P. 29

A method is proposed for calculating final-state interaction effects for deuteron electrodisintegration, which is based on the relativistic-diagram technique. Expressions are obtained for the vertex functions $\Gamma_{NN}$ and the nuclear electromagnetic current. The $\Gamma_{NN}$ аге determined from the invariant nucleon-scattering amplitude. The proposed formalism enables one to determine the final-state interaction in terms of partial N-N scattering amplitudes outside the energy surface.

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The Gell-Mann and Okubo mass formula in the baryon quark-parton model

The Gell-Mann and Okubo mass formula in the baryon quark-parton model

L. Jelmy (Luxemburg), V.S. Zamiralov

Moscow University Physics Bulletin 1985. 40. N 5. P. 32

It is shown that allowance for the quark-parton baryon structure enables one to derive the Gell-Mann and Okubo mass formula for the quark model. The masses of the $\Lambda$ and $\Sigma$ hyperons are nondegenerate. It is notable that in this approach, there are relationships between the realization of F and D forms of coupling and the quark distributions in the baryons.

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Radiophysics

An apparatus for examining injection-laser modulation characteristics

An apparatus for examining injection-laser modulation characteristics

A.S. Logginov, I.P. Spir'kov

Moscow University Physics Bulletin 1985. 40. N 5. P. 35

An apparatus, is described for examining transient processes and for recording watt-ampere and quasi-resonant emission characteristics from injection lasers working under pulse conditions and with pulse-code modulation. The risetime of pumping current pulse does not exceed 1 nsec, while the interval between two pulses in a code sequence is set in the range 0-20 nsec, which enables one to examine the modulation characteristics at frequencies close to the limiting one.

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Striation excitation in a conical discharge tube

Striation excitation in a conical discharge tube

B.P. Aleksandrov, P.S. Landa, B.N. Shvilkin

Moscow University Physics Bulletin 1985. 40. N 5. P. 40

The excitation of ionization-diffusion waves (striations) is considered for the positive column of a direct-current discharge in a conical tube at high current levels. The condition for striation self-excitation is derived. It is found that the upper self-excitation limit for argon in tubes with small semivertex angles is lower than that in a cylindrical tube whose radius lies between the radii for the ends of the cone.

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Effects of mechanical pressure on potassium tantalate UHF dielectric resonators

Effects of mechanical pressure on potassium tantalate UHF dielectric resonators

G.V. Belokopytov, I.V. Ivanov, N.E. Lebedev, A.A. Kharin

Moscow University Physics Bulletin 1985. 40. N 5. P. 46

A study has been made of the effects of uniaxial mechanical pressure on the dielectric constant and dielectric loss of $KTaO_3$ crystals at 4.2 К over the range 0.5-1.28 GHz. As the pressure increases, the resonant frequency of the $H_{01\delta}$ mode in a cylindrical resonator decreases monotonically. There is a considerable increase in the dielectric loss in $KTaO_3$ when an inhomogeneous pressure is applied. This agrees with the view that charged line defects (dislocations) multiply in $KTaO_3$ crystals under pressure.

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A metal-insulator resonator in a three-circuit frequency-stabilization system

A metal-insulator resonator in a three-circuit frequency-stabilization system

I.I. Minakova, B.G. Simeonova (Bulgaria)

Moscow University Physics Bulletin 1985. 40. N 5. P. 50

Results are presented on a UHF oscillator stabilized by a metal-dielectric resonator. Frequency-response curves and quality-factor data are given for the resonator modes and the stabilization coefficients at room temperature.

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Optics and spectroscopy

Theory of orientational self-focussing in a light wave of ordinary type

Theory of orientational self-focussing in a light wave of ordinary type

A.S. Zolot'ko, V.F. Kitaeva, N.N. Sobolev, A.P. Sukhorukov

Moscow University Physics Bulletin 1985. 40. N 5. P. 53

A theoretical study is made of the interaction between the director for a homeotropically oriented nematic liquid crystal and a light wave of ordinary type at inclined incidence. Various methods are employed to calculate the director-reorientation threshold in response to a plane wave and a bounded beam. An oscillatory state is detected from the numerical solution of the equations describing the director reorientation within the framework of a simple model.

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An automated laser system for examining nonlinear molecular absorption

An automated laser system for examining nonlinear molecular absorption

M.S. Dzhidzhoev, A.V. Chugunov

Moscow University Physics Bulletin 1985. 40. N 5. P. 61

A laser system is described that has an automated recording system and is used for examining processes in molecular gases under conditions of IR-IR and UV excitation.

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A spin stabilizer containing $^{129}Хе$ nuclei oriented by exchange interaction

A spin stabilizer containing $^{129}Хе$ nuclei oriented by exchange interaction

Z.B. Iskandarov, L.S. Kornienko, A.L. Kotkin, R.M. Umarkhodzhaev

Moscow University Physics Bulletin 1985. 40. N 5. P. 66

Experimental studies have been performed on a $^{129}Хе$ stabilizer, with the nuclei polarized by exchange interaction with potically oriented $^{133}Cs$ atoms. This spin stabilizer based on oriented $^{129}Хе$ operates with magnetic fields of 5-500 nT.

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Energy dependence of the direct-photoionization polarization and correlation characteristics for the 3P state of the sodium atom

Energy dependence of the direct-photoionization polarization and correlation characteristics for the 3P state of the sodium atom

V.V. Balashov, A.N. Grum-Grzhimailo, B. Zhadamba (Mongolia)

Moscow University Physics Bulletin 1985. 40. N 5. P. 69

A theoretical study is made of photoionization for excited states of the sodium atom $1s^22s^22p^23p^2P_J$ at energies up to 3 Rу. The energy dependence of the parameters completely describing the process has been derived. The photoabsorption cross section, the polarization, and the angular distributions of the photoelectrons are examined for conditions characteristic of current experiments.

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Acoustics and molecular physics

Polarization effects in the propagation of magnetoelastic waves in hematite

Polarization effects in the propagation of magnetoelastic waves in hematite

T.A. Mamatova, V.G. Prokoshev

Moscow University Physics Bulletin 1985. 40. N 5. P. 73

Studies have been made on the effects of the magnitude and direction of an external magnetic fied in the frequency range 10-45 MHz on the polarization, damping, and velocity of magnetoelastic waves in hematite. It is found that the damping is strongly dependent on frequency for field strengths less than 2 kOe. When the field is reduced from 4 kOe to 0.05 kOe, the velocity is reduced by more than 40%. It has been shown by experiment that one can rotate the shear-wave's plane of polarization through 90° by altering the field strength and direction.

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Ternary correlations in liquids

Ternary correlations in liquids

P.V. Elyutin

Moscow University Physics Bulletin 1985. 40. N 5. P. 79

Determining the three-particle distribution $g_3$ is considered for an equilibrium system in which the particles interact via a pair potential. The form of $g_3$ is determined from a variational principle for the free energy by the use of the second equation in the BBHCI chain to provide additional conditions in conjunction with the correlation-attenuation principle. A study is made of the behavior of $g_3$ in configurations near the most likely one; this agrees with published data from computer experiments and virial expansion.

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Describing the properties of a substance in a wide range around the critical point

Describing the properties of a substance in a wide range around the critical point

L.P. Filippov

Moscow University Physics Bulletin 1985. 40. N 5. P. 83

It is shown that one can use variables characterizing the distance of a point in the $\rho T$ diagram from the spinodal and the symmetry line to obtain a phase diagram that is the same for different substances. In this diagram, segments of straight lines represent the spinodal, binodal, critical isotherm, and symmetry line. These variables also enable one to formulate a simple equation of state for a wide region around the critical point.

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Biophysics

The effects of oxygen on electron transport in green-leaf photosynthetic apparatus

The effects of oxygen on electron transport in green-leaf photosynthetic apparatus

A. Vasaros (Hungary), M.K. Solntsev, A.K. Kukushkin, V.A. Karavaev

Moscow University Physics Bulletin 1985. 40. N 5. P. 89

Oxygen has an effect on green-leaf thermoluminescence. The strengths of the peaks apart from the A one are dependent on the environment $O_2$ concentration. The sum of the B and С peaks falls to zero in the absence of $O_2$. To produce these peaks requires the presence of oxygen only during the heating. There is assumed to be negative feedback between the oxygen producing system and the $O_2$ concentration.

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Astronomy

Representing the potential of a general body as a series convergent everywhere outside its surface

Representing the potential of a general body as a series convergent everywhere outside its surface

N.A. Chuikova

Moscow University Physics Bulletin 1985. 40. N 5. P. 95

Mittag-Loffler expansion has been used for the reciprocal of the distance as the potential of a planet in terms of spherical functions, with the series converging everywhere outside the surface; an estimate is made of the representativeness.

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Solid state physics

Effects of external factors on acoustoelectronic storage in a piezoelectric-semiconductor structure

Effects of external factors on acoustoelectronic storage in a piezoelectric-semiconductor structure

I.Yu. Solodov, G.Yu. Timofeeva

Moscow University Physics Bulletin 1985. 40. N 5. P. 100

A study has been made of the effects of evacuation, transverse electric fields, illumination, and temperature change on acoustoelectronic storage in a layered piezoelectric-semiconductor structure. Some parameters have been determined for the surface states in the semiconductor, and information has been obtained on the trapping and recombination kinetics.

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Effects of previous illumination on the conductity of an undoped film on amorphous, hydrogenated silicon

Effects of previous illumination on the conductity of an undoped film on amorphous, hydrogenated silicon

I.A. Kurova, N.N. Ormont, V.D. Podrugina

Moscow University Physics Bulletin 1985. 40. N 5. P. 105

Observations have been made on the conductivity changes in a-Si:H films and in the activation energy after preliminary illumination, and also on the suppression of the temperature-dependent quenching of the band-band photoconductivity and superlinearity in the lux-ampere characteristics; explanations are given via the formation of an additional concentration of broken silicon bonds, which acquire a donor or acceptor character and correspondingly displace the Fermi level $E_F$ upwards or downwards in accordance with the equilibrium position of that level in the film. The recombination model is discussed.

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