Faculty of Physics
M.V.Lomonosov Moscow State University
Physics of nuclei and elementary particles

## Diagnostics of atoms encapsulated into fullerenes by the polarization bremsstrahlung from accelerated

### V.K. Grishin$^1$, D.P. Nikitin$^2$

Moscow University Physics Bulletin 2012. 67. N 3. P. 241

It is shown that the polarization bremsstrahlung (PB), which arises during scattering of coherent electromagnetic fields of fast charged particles by atomic electrons and resonantly reacts to changes of the density of a substance, allows one to diagnose the states of atoms that are encapsulated in fullerene. As a result of modeling, by comparing the spectra of an empty fullerene and fullerene with an encapsulated atom and using difference fitting, it is possible to detect compressions or expansions of an electron shell of the atom that is encapsulated in a fullerene. The calculations are fulfilled for the model approximation of the P@C60 endohedral compound.

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## Production of the isotope $^{18}$F in the reaction $^{23}$Na$(\gamma,\alpha n)^{18}$F at ${E_b=55}$ MeV

### S.S. Belyshev$^1$, L.Z. Dzhilavyan$^2$, A.N. Ermakov$^3$, B.S. Ishkhanov$^{1,3}$, A.I. Karev$^4$, V.G. Raevsky$^4$, V.V. Khankin$^3$, V.I. Shvedunov$^3$

Moscow University Physics Bulletin 2012. 67. N 3. P. 246

The activity of $^{18}$F that was produced in the $^{23}$Na$(\gamma,\alpha n)^{18}$F reaction with the maximum bremsstrahlung energy ${E_b=55}$ MeV was measured.

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## Inertial detection of noise using a Schottky diode with $\delta$-doping

### A.V. Klyuev

Moscow University Physics Bulletin 2012. 67. N 3. P. 251

We investigated the simplest statistical characteristics of a process after inertial detection of noise using a Schottky diode with $\delta$-doping.

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## Size dependences of the polarizability of the metal particles

### G.V. Belokopytov, A.V. Zhuravlev, Yu.E. Terekhov

Moscow University Physics Bulletin 2012. 67. N 3. P. 255

Size dependences of the eigenfrequencies, quality factors and polarizabilities of small metallic particles-resonant radiating elements were examined. Limits of electrodynamic scaling regions and ones of plasmon oscillations predominance were established for two types of particles-spling-ring and core-shell resonators.

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Condensed matter physics

## Simulation of thermally-induced processes of diffusion and phase formation in layered metal-metalloid systems

### V.S. Rusakov$^1$, I.A. Sukhorukov$^1$, A.M. Zhankadamova$^2$, K.K. Kadyrzhanov$^2$

Moscow University Physics Bulletin 2012. 67. N 3. P. 263

A physical model of thermally induced processes of diffusion and phase formation in layered metal-metalloid systems is offered. The software for the model is created, which allows one to quantitatively describe the kinetics of these processes under arbitrary modes of annealing. The results of theoretical computations are compared with the data of experimental studies of a $^{57}$Fe:O$^{+}$ layered implantation system using the methods of Mössbauer spectroscopy. The agreement between the numerical and experimental results indicates that the nature of phase transformations in the investigated system is determined by a change in the local concentration of the metalloid during its interstitial diffusion and corresponds to peculiarities of the phase equilibrium diagram of the Fe-O binary system.

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## Microwave diagnostics of the influence of physical effects on the electromagnetic characteristics of water

### A.A. Barzov$^1$, A.L. Galinovskii$^1$, N.N. Sysoev$^1$, A.E. Postel’ga$^2$, A.D. Usanov$^2$, D.A. Usanov$^2$, A.V. Khakhalin$^1$

Moscow University Physics Bulletin 2012. 67. N 3. P. 269

Changes in the dielectric constant and dielectric loss tangent of water that was first subjected to impact loads under the action of an alternating magnetic field were determined quantitatively using a micro-wave system, which allows solution of the inverse problem. The results of measurements of the optical spectrum of water in the “transmission” mode, which was subjected to a shock load, in comparison with the optical spectrum of distilled water, are described.

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Biophysics and medical physics

## Molecular and supramolecular structures in biological fluids and their homochiral models

### S.V. Stovbun, A.A. Skoblin

Moscow University Physics Bulletin 2012. 67. N 3. P. 274

The structures of homochiral solutions that simulate biological fluids were studied. Dynamic light scattering revealed three structural groups in them, viz., (1–10) nm (molecular associations); 10 μm (strings), and 1 μm (isometric grains). IR spectroscopy and chirotropical measurements confirmed the presence of associations. We considered a statistical model for the formation of molecular association and the formation of strings in the average field of associations.

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## Chirotropical phenomena in biological fluids and their homochiral models

### S.V. Stovbun, A.A. Skoblin

Moscow University Physics Bulletin 2012. 67. N 3. P. 278

The strong and non-monotonous dependence of chirotropical properties of biological fluids and their homochiral models on the concentration of chiral substance was found, which is associated with the formation of complex, supramolecular structures that consecutively replace each other, viz., molecular associations and strings, and with an increase in the magnitude of the delocalization of the excited electron states of chromophore groups. The rule of consistent change in the sign of chirality was formulated upon the formation of chiral phases, which replace each other.

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Astronomy, astrophysics, and cosmology

## Diagnostics of the region of nuclear interactions of neutrons in the solar flare of January 20, 2005 by gamma-ray lines

### E.V. Troitskaya$^1$, I.V. Arkhangel’skaya$^2$, A.I. Arkhangel’skii$^2$

Moscow University Physics Bulletin 2012. 67. N 3. P. 282

Based on an analysis of the time history of the count rate in the 2.223 MeV neutron-capture line from the extreme solar event of January 20, 2005, we investigate the density of the surrounding medium and the $^3$He content in the area of the 2.223 MeV gamma-line production. The analysis uses data on count rates in the 2.223 MeV gamma-ray line, as well as in lines ranging from 4 to 7 MeV, which were acquired with the AVS-F apparatus from the SONG-D detector onboard the CORONAS-F satellite. It is shown that simulation of the time history of the 2.223 MeV gamma-ray line from the flare event would require an assumption of the elevated abundance of $^3$He. It is found that in the area of the 2.223 MeV gamma-line production the ratio $n(^3\mbox{He})/n(^1\mbox{H})$ is (${(1.4\pm0.15)\cdot10^{-4}}$, although, based on the data from different flares, on average it is approximately ${2\cdot10^{-5}}$. The elevated abundance of 3He may be considered as an additional indirect argument for the possible presence of reaction products of neutron radiative absorption by the $^3$Не isotope within a small increase in gamma emission in the 15–21 MeV range over the background level (which was detected previously from the CORONAS-F/AVS-F data).

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Physics of Earth, atmosphere, and hydrosphere

## Electromagnetic fields in tornados and spouts

### S.A. Arseniev, N.K. Shelkovnikov

Moscow University Physics Bulletin 2012. 67. N 3. P. 290

The electrical and magnetic fields in tornados and spouts were calculated on the basis of theoretical data. The calculation results were compared to the data from observations.

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Theoretical and mathematical physics

## The temperature distribution in a flat conductive disk heated by a direct current

### T.N. Gerasimenko, P.A. Polyakov

Moscow University Physics Bulletin 2012. 67. N 3. P. 296

The problem of the steady-state temperature distribution in a flat conductive disk that is heated by a direct current was investigated. An analytical solution was obtained and limiting cases corresponding to different mechanisms of heat transfer were examined. It was determined that the peak value of the temperature and its distribution in such a disk are strongly governed by the ratio of the heat transfer coefficient to the coefficient of heat conductivity. High values of this ratio correspond to a highly non-uniform distribution of temperature (a hot spot). Low values correspond to a smooth decrease in temperature from the center to the boundaries of the conductor.

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Physics of nuclei and elementary particles

## The calculation of the speed performance of the CLAS12 silicon vertex tracker

### E.O. Kurbatov$^1$, M.M. Merkin$^1$, S.V. Rogozhin$^2$

Moscow University Physics Bulletin 2012. 67. N 3. P. 300

The CLAS12 experiment is intended to study the generalized parton distributions in exclusive reactions. The CLAS12 Silicon Vertex Tracker must provide the registration of all reaction products at the expected high luminosity. The results of a GEANT4 simulation of the expected physical rates in the SVT are presented. The frequency of the noise hits of the readout electronics is determined on the basis of the capacitive load generated by the attached sensors. In order to find the fraction of the events that are lost due to delays in the readout electronics, a computer simulation of the logic of the data-driven readout FSSR2 chip is performed. At a signal-to-noise ratio of 8 to 1 the readout electronics are capable of processing the expected rates, provided a registration threshold of 0.4 mip is preset.

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Optics and spectroscopy. Laser physics

## Propagation of a short electromagnetic pulse in a linear medium with frequency and spatial dispersion: Direct integration of the Maxwell equations by the finite difference method

### V.A. Makarov, I.A. Perezhogin, N.N. Potravkin

Moscow University Physics Bulletin 2012. 67. N 3. P. 304

The specific features of the propagation of a short (on the order of ten oscillations) electromagnetic pulse in an isotropic linear medium with frequency and spatial dispersion, which were established via integration of a system of Maxwell equations by the finite-difference time-domain method using an auxiliary differential equation, are discussed. The variation of the direction of the electric field-strength vector oscillations that occurs in an optically active medium upon propagation of a linearly polarized ultrashort pulse incident on it is shown to be significantly different from the rotation of the polarization plane (proportional to the propagation coordinate) in the case of the incidence of a long pulse.

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Chemical physics, physical kinetics, and plasma physics

## Ignition of thin liquid hydrocarbon films via surface microwave discharge generated in a paired-pulse mode

### V.M. Shibkov, L.V. Shibkova, P.V. Kopyl, O.A. Surkont

Moscow University Physics Bulletin 2012. 67. N 3. P. 308

The process of ignition and combustion of liquid hydrocarbon films under the conditions of a self-maintained surface microwave discharge in still air that is generated on a dielectric antenna in the paired pulse mode is investigated. The effect of the medium pre-excitation, which occurs during the first pulse on the period of induction and intensity of hydrocarbon combustion during the second microwave pulse, is demonstrated.

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## Determination of plasma characteristics in the plasma of a pulsed discharge propagating over a water surface using spectral methods

### A.F. Aleksandrov, D.N. Vaulin, Ren Qi, V.A. Chernikov

Moscow University Physics Bulletin 2012. 67. N 3. P. 312

The results of spectral investigations of the electron density and excitation temperature in the plasma of a pulsed discharge propagating over a liquid surface are presented.

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