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

Moscow University Physics Bulletin 1983. **38**. N 4. P. 1

We consider some problems in the design of multilayered optical coverings for oblique incidence of light, such as the determination of the required transmission coefficient in unpolarized light, the required transmission coefficient for light of one of two possible polarizations, and the synthesis of a covering for given requirements on the transmission coefficients for waves with various polarizations. We present algorithms for the solution of these problems, and give concrete examples of the synthesis.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 7

We develop and test a pyroelectric IR radiometer which is designed for the control of temperature regimes of machine components fabricated on a production line. The temperature control is realized by registering the thermal radiation of heated components in the spectral range 8-12 μm using a pyroelectric radiation sensor. The chosen spectral range makes it possible to operate in conditions of increased humidity and smoke content, and also in the presence of cinder on the components. In the range of measured temperatures 100-1000°C, the error of measurements is ±1-3%, and in the range 1000-1300°C ± 1%. The device operates at a distance from the heated components from 1 to 5 m, and has an internal temperature-calibrated indication system. We foresee the output to a pen recorder, and an inclusion of generators of induction heating in the feedback circuit for the power control.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 11

We discuss the effect of a strong modulating field and the presence of random impurity field in the sample on the resonant structure of the coefficient of nonlinear polarizability.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 16

An asymptotic analysis of the fundamental solution of the equation for the propagation of pressure perturbations shows that it is possible to use a point receiver to determine the distance to an instantaneous point source in a viscous compressible liquid. We also give a formula for the determination of the amplitude of the source using the pressure measured at the observation source.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 20

Using the quantum Green's function formalism, we study the preequilibrium emission of complex particles in reactions of the form $A(\alpha, \beta)B$. After statistical averaging, we obtain expressions for the differential cross-sections of the reaction which is caused by the mechanism of the multistep direct process, multistep process via the compound nucleus, and to the combined multistep process. We obtain estimates of the factor for the transition "complex particle $\leftrightarrow$ quasi-particles".

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 26

We consider the model of a measuring computational complex "device + computer" in the linear problems of reduction of experimental data. We obtain results which make it possible to characterize the complex in terms of "device" parameters. We introduce and study the idea of quality of a model in the reduction problems.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 31

We study experimentally the constants of the electric fields which arise in a stationary high-frequency discharge. We study the dependence of the decay of the voltage of the constant electric field $V_{\sim}$ on the high-frequency voltage $V_{\sim}$, the gas pressure p, the frequency of the high-frequency fields f, the type of gas, and material of the electrodes. We study a symmetric high-frequency discharge in a tube with planar internal electrodes in helium and neon for p $\sim$ 10-1300 Pa in the frequency range 1-12 MHz, i.e., in conditions when $f/v\ll 1$, where v is the electron-atom collision frequency. We determine the specific methodological features of the experimental scheme for the measurement of $V_0$. In the condition under investigation, we observed values $V_0\le 1000$ V. It is established that the quantity $V_0$ depends considerably on the intensity of the emission processes which are determined by the combination of the working gas and the material of the electrode. The form of the observed dependence $V_0(f)$) depends considerably on the amplitude of the high-frequency voltage $V_{\sim}$ and, in the region of frequencies under investigation, is determined by the character of the ion motion in the vicinity of the discharge electrode.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 37

The methods of photocharge injection and electron paramagnetic resonance are used in the germanium - germanium dioxide-adsorbed dye (coumarin) structures to obtain information about the transition of the $E_1$- and $E_2$-oxide centers from a nonparamagnetic to a paramagnetic state when the dye molecules are excited. It is shown that in the structures with adsorbed dye, the electron transitions in the solid are stimulated by the migration of electronic excitation which takes place in the direction from the adsorbed molecules to the defects in the oxide layer, as well as in the· direction from the oxide defects which capture carriers, to the adsorbed dye molecules.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 42

We study the effect of wind on the flow along an inclined plane. It is proved that the spiral rotation of the velocity vector with depth which is observed in shallow basins, is due to a combined action of the wind, the incline of the floor, and the Earth's gravity. The theory explains the results of measurements in the estuaries of the Volkhov and Volga Rivers.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 47

We discuss briefly the elementary part of the three-valued logic of D.A. Bochvar (sentential calculus), and use the symbols of this calculus to formulate sufficient conditions for the meaninglessness of equalities and inequalities of scalar and vector phsyical quantities. We also formulate the sufficient conditions for the equality of dimensions of these quantities. It is asserted that analogous formulas are valid also for matrices all of whose elements have identical dimensions and are measured in identical units.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 54

We use the representation of Green's function of the stochastic Helmholtz equation in the form of a path integral which makes it possible to carry out explicitly the averaging in the boundary-value stochastic problems, and reduce the problem to a deterministic one. The functional integrals are evaluated by the method of stationary phase. The obtained solution takes into account both forward and backward multiple scattering.

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

Moscow University Physics Bulletin 1983. **38**. N 4. P. 59

We obtain analytical expressions for the calculation of the electric field distribution of a standing wave in resonant multilayered interference systems with weakly-absorbing layers whose optical thickness at the resonant wavelength is a multiple of $\pi/2$. By way of example, we obtain the field distribution in a multilayered interference absorber.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 63

The method of adiabatic calorimetry is used to study the temperature dependences of the monocrystals of triglycine sulfate, alloyed with the impurities $Cu^{2+}$ and $Cu^{2+}+L-\alpha$-alanine in the temperature range 240-350 K. The copper impurity causes an insignificant change (in comparison with the pure crystal) of the temperature dependences of the heat capacity in the region of the phase transition which, however, sharply increase for the copper-alanine impurity. The observed effects can be explained using the concept of displacement field inside the crystal.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 67

We present the results of a numerical experiment on a computer, carried out using an algorithm for the calculation of complex transverse wave numbers of the dispersion equation. These results confirm the earlier conclusions of an analytical theory about the existence of regimes with anomalously small damping of the $E_{0n}$-waves in a planar corrugated waveguide.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 70

In the formalism of C* algebras, we construct an operator for the transition between nonequivalent vacua. This makes it possible to prove a number of properties of the field models with spontaneous symmetry breaking.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 73

We study the localized states in amorphous hydrogenated silicon, obtained by HF discharge in monosilane, by the method of volt-farad characteristics of a Schottky diode in the frequency range 1-10 Hz. We determine the density of states for zero bias ($1,5\cdot 10^{17} ev^{-1}\cdot cm^{-3}$). This quantity agrees with the results of other methods. By comparing the experimental frequency dependence of the capacitance with the theoretical curve using two adjustable parameters, we determine the effective electron capture cross section of the trap ($10^{-14} cm^2$).

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 76

We discuss the possibility of obtaining a simultaneous generation on a number of vibrational-rotational levels of three different bands of the $CO_2$ molecule in the TEA laser. The tuning of the line is carried out by changing the temperature of the intraresonator cell with the carbon-dioxide gas.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 79

We study the electrical resistance $\rho$, the thermoelectric force $\alpha$, the magnetoresistance $\Delta\rho/\rho$, the spontaneous magnetization $\sigma_s$ and the Curie temperature $Т_c$ of monocrystalline manganites $La_{0,6}Pb_{0,4}Fe_yMn_{1-y}O_3$ for y = 0; 0.10; 0.15, and 0.22 in the temperature range from 80 to 800 K and in magnetic fields up to 14 kOe. It is established that the manganites under study are magnetic semiconductors whose width of the forbidden gap is, in order of magnitude, comparable with the energy of the exchange interaction. This causes a metal-semiconductor transition in the neighborhood of the Curie temperature. The replacement of Mn ions by the Fe ions leads to an increase of $\rho$ and of the activation energy $\Delta E$, and to a decrease of the Curie temperature $Т_c$ and of the spontaneous magnetization.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 83

We obtain the matrix elements of the spin density matrix of the nucleus $^{12}С$ in the state 2+, 4.44 MeV, excited in the processes $(\pi, \pi')$ and $(\pi, 3\pi)$ at momentum 40 GeV/sec. We determine the regions of the transferred momentum where the angular distribution of the gamma quanta from the de-excited level is most sensitive to the dynamics of the process.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 88

We present the results of direct measurements of the ratio of concentrations of the negative ions and electrons in a mierowave discharge at pressure p = 0.1 Torr, and in a non-self-maintained Townsend discharge at pressure p = 50-760 Torr. The method of measurement is based on the introduction of a high-frequency filter in the gas during the application of a weak diagnostic constant field.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 91

We consider the radiation of stationary sources of magnetic field in a slowly moving medium whose velocity varies with time. The obtained expressions for the angular and spectral distributions of the emitted energy are used to calculate the radiation of a magnetic dipole and of a constant current.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 95

Using an earlier method based on the three-particle Faddeev equations modified for the Coulomb potentials, we study the effect of interaction of the incident particles with the nucleus of the target atom on the double differential inonization cross sections. It is shown on the example of the helium-atom ionization that taking into account this interaction improves the agreement of the theory with experiment in a wide range of energies of the colliding particles.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 99

We study the effect of external constant crossed field on the behavior of the nuclear beta decay for arbitrary values of the released energy. We compare our results with the case when the beta decay takes place under the influence of a strong electromagnetic wave.

Show AbstractMoscow University Physics Bulletin 1983. **38**. N 4. P. 103

We present a method for the study of the circulation of liquid which uses a thermohydrometer and the Pitot tube. The method makes it possible to observe the existence of a transverse circulation in the riparian region of a direct channel flow.

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