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Propagation of a light pulse in a semiconductor

Propagation of a light pulse in a semiconductor

T.M. Il'inova, T.V. Ishchenko, I.M. Sorokina

Moscow University Physics Bulletin 1986. N 3.

The self-consistent problem of incoherent photoexcitation of a straight-band nondegenerate intrinsic self-conductor is considered in the limiting cases of slow and fast electron-electron relaxation. A dependence of the concentration of free charge carriers on the pumping energy is obtained. The absorption of the pulse propagating in the semiconductor is studied.

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Time-of-flight effects in crystals of reduced titanium dioxide in the presence of space-charge-limited currents

Time-of-flight effects in crystals of reduced titanium dioxide in the presence of space-charge-limited currents

V.L. Kashintseva, G.I. Ovchinnikova, A.B. Snedkov

Moscow University Physics Bulletin 1986. N 3.

Effects associated with the time of flight of charge carriers through the crystal volume in rutile-based materials in the presence of carrier injection from the contacts and of space-charge-limited currents are observed. Measuring the time of flight of injected charge carriers allows the microscopic mobility of the charge carriers in single crystals of reduced rutile to be determined.

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Accuracy of the moments of the angular distribution of electron-photon cascades

Accuracy of the moments of the angular distribution of electron-photon cascades

I.P. Ivanenko, V.V. Sizov

Moscow University Physics Bulletin 1986. N 3.

For the example of angular moments, the sensitivity of the angular characteristics of electron-photon cascades to details of the description of elementary interactions is investigated. The physical accuracy of models widely used to describe Rutherford scattering is studied: the Landau and small-angle approximations, and the case when screening and the finite nuclear dimensions are taken approximately into account. Specific calculations are made for the mean cosine and the mean-square angle for electrons and photons in air and lead.

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Experiment on the nuclear composition and energy spectra of solar cosmic rays on the Prognoz-9 spacecraft

Experiment on the nuclear composition and energy spectra of solar cosmic rays on the Prognoz-9 spacecraft

S.A. Belyakov, Ju.P. Gordeev, Yu.I. Denisov, G.Ya. Kolesov, A.N. Podorol'skii, B.A. Nikitin

Moscow University Physics Bulletin 1986. N 3.

An instrument with semiconductor telescopes is described; the basic factors determining its resolving power are considered; experimental data characterizing the operation of the instrument on a spacecraft are given.

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Solution of the Helmholtz equation in a strip with piecewise-constant non-self-conjugate boundary conditions

Solution of the Helmholtz equation in a strip with piecewise-constant non-self-conjugate boundary conditions

V.P. Modenov

Moscow University Physics Bulletin 1986. N 3.

A scheme for the orthogonal Galerkin method is constructed on the basis of generalization of the partial-region method to a complex space with a pseudoscalar product. This scheme is applicable to the solution of the boundary problem for the Helmholtz equation in a strip with piecewise-constant non-self-conjugate boundary conditions of impedance type.

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Accuracy and reliability of experimental interpretation

Accuracy and reliability of experimental interpretation

Yu.P. Pyt'ev

Moscow University Physics Bulletin 1986. N 3.

The accuracy of experimental interpretation is determined by the model of the measurement scheme adopted and so does not allow the experimental results to be fully characterized if the reliability of the model is unknown. The concept of the reliability of the model is defined and analyzed in the present work as the minimum probability of erroneous rejection of the model on the basis of measurement results in some set of alternatives.

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Asymptotic investigation of the rapid growth in the second moment of a magnetic field in a mirror-symmetric flow

Asymptotic investigation of the rapid growth in the second moment of a magnetic field in a mirror-symmetric flow

O.V. Artamonova, D.D. Sokolov

Moscow University Physics Bulletin 1986. N 3.

An asymptotic solution of the Kazantsev equation is constructed in the limit of high magnetic Reynolds numbers; the rate of growth in the energy, the excitation threshold, and the structure of the magnetic-field correlation function are calculated, and compared with the results of numerical integration of the Kazantsev equation.

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Relativistic spectrum of a two-meson bound state in scalar electrodynamics

Relativistic spectrum of a two-meson bound state in scalar electrodynamics

A.P. Martynenko, R.N. Faustov

Moscow University Physics Bulletin 1986. N 3.

Within the framework of scalar electrodynamics, the construction of an interaction operator of two scalar particles is considered for the local quasi-potential equation obtained by the "rationalization" method from the Logunov-Tavkhelidze equation. The relativistic spectrum of a two-meson bound state is calculated with an accuracy of $\alpha^{4}$.

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Polarization and magnetization in neutral rotating bodies

Polarization and magnetization in neutral rotating bodies

V.I. Grigor'ev, E.V. Grigor'eva

Moscow University Physics Bulletin 1986. 41. N 2. P. 1

Polarization produced by gravitational and centrifugal fields is considered on the basis of a unified macroscopic theory that provides realistic estimates for the magnetic fields of celestial bodies as well as the fields observed in laboratory experiments.

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Optimal data reduction in physics experiments

Optimal data reduction in physics experiments

P.V. Golubtsov, Yu.P. Pyt'ev, A.I. Chulichkov

Moscow University Physics Bulletin 1986. 41. N 2. P. 7

Designing a measuring instrument is considered for the best measurement of a random signal having known mathematical expectation and correlation operator; the instrument is chosen from the class satisfying the technological design conditions of the type of constraint on the dimensions of the vector representing the measurement results or the response energy to an input test signal. A relationship is considered between the methods used and the optimal mean-square estimation ones.

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