Faculty of Physics
M.V. Lomonosov Moscow State University

# Issue 5, 2019

Chemical physics, physical kinetics, and plasma physics

## Microwave discharges and their application I. Surface microwave discharge

### V. M. Shibkov

Moscow University Physics Bulletin 2019. N 5.

The review presents the results of the fundamental research cycle, carried out at the Faculty of Physics of the Moscow State University, a new type of surface microwave discharge. The discharge was created by a surface wave on a dielectric antenna when a powerful electromagnetic radiation of a centimeter wavelength range was brought to it. The basic properties of the microwave discharge and the spatial and temporal evolution of the parameters of the plasma produced by a surface discharge are studied in a wide range of changes in the external conditions.

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Biophysics and medical physics

## Natural selection as a percolation system

### A. E. Sidorova

Moscow University Physics Bulletin 2019. N 5.

The role of natural selection in biological evolution is described systematically reflecting modern biological concepts. A new approach, based on the ideas regarding the physical phenomenon of percolation, was suggested and developed to generalize the theoretical and mathematical description of this key problem of biology. The natural selection of optimal variants in the evolutionary mutation flow is considered a percolation filter as a physical tool constituting the selection mechanism. The model is based on the concept of self-organization in hierarchical structures of speciation where the trigger properties of the cell (node), like a valve, define the deterministic component of new mutations fixation and the drift defines the collective behavior of the percolation lattice nodes and connections (mutations) that introduces an element of randomness to the process of new mutations fixation in mutation streams. As a result, considering various values of the selection and drift coefficients, as well as the ratio of prohibiting and permitting mutations, the modes of mutations fixation in generations were obtained at the population level.

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Theoretical and mathematical physics

## New design of a 4-bit ripple carry adder on a Nano-scale quantum dot cellular automata

### S. Seyedi, G. Alireza, N. Jafari Navimipour

Moscow University Physics Bulletin 2019. N 5.

Quantum-dot cellular automata (QCA) is a new computing paradigm based on cellular automata with appealing characteristics such as high speed, low power consumption, and high density for realizing quantum computers. On the other hand, adder is the primary circuit in any digital processor and ripple carry adder is a basic building block of other adders. Therefore, efficient design of this type of adder may lead efficient design of whole system. So, in this paper, a new design of ripple carry adder is proposed to decrease the number of cells and area as possible. Simulation results using QCADesigner verifies the correctness of the proposed circuit and validates its efficiency in terms of number of cells and area.

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## To the Explanation of the Magnetoplastic Effect in Diamagnetic and Paramagnetic Solids

### N. E. Smirnov

Moscow University Physics Bulletin 2019. N 5.

This work is devoted to the theoretical study of the magnetoplastic effect that manifests itself in motion of dislocations in solids in magnetic fields in the absence of mechanical loading. An expression is obtained for the effective magnetic charge per length unit of dislocation which emerges due to the action of the magnetic field on the dislocation. The effects associated with the emergence of the induced magnetic charges at dislocations are studied. It is shown that the effective magnetic charge appears due to the interaction of the magnetic field only with the edge components of dislocations. The expression is obtained for the force that acts on a dislocation in the magnetic field and it is shown that in the experiments on studying the motion of dislocations in magnetic fields, the determining role must be played by the projection of this force on the glide plane of dislocation.

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## Мagnetoresistive features of the long FeNiCo nano strip

### V. S. Shevtsov$^{1,2}$, O. P. Polyakov$^{1,2}$, V. V. Amelichev$^3$, S. I. Kasatkin$^2$, P. A. Polyakov$^1$

Moscow University Physics Bulletin 2019. N 5.

A theory has been developed to explain the experimental dependence of the magnetoresistance of the FeNiCo nano strip on the external magnetic field. The theory is based on the assumption of a one-dimensional nonuniformity of the distribution of magnetization in a nano strip, which makes it possible to implement an effective algorithm for solving the micromagnetic equilibrium problem. It is shown that the developed theory is in good agreement with the calculations of the specialized OOMMF package, but significantly exceeds it in performance for such problems.

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## The hydrogen atom above the plane with the not going through'' boundary condition

### S. A. Artyukova, K. A. Sveshnikov, P. K. Silaev, A. V. Tolokonnikov

Moscow University Physics Bulletin 2019. N 5.

The behavior of the electronic levels of a hydrogen atom in half-space bounded by a flat surface, on which the electron wave functions satisfy the condition of not going through'' the boundary, is considered. It is shown that in the process of adsorption of hydrogen atoms by a sample with a clean smooth surface, high affinity and a low initial concentration of hydrogen inside, a significant amount of energy can be released. The results were obtained both with the direct numerical calculation using the finite element method and with the variational estimates based on the special selection of trial functions.

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## Pion condensation in hot dense quark matter with isotopic and chiral-isotopic imbalances in the framework of the Nambu--Jona-Lasinio model.

### T. G. Khunjua$^1$, K. G. Klimenko$^2$, R. N. Zhokhov$^3$

Moscow University Physics Bulletin 2019. N 5.

Hot dense quark matter with isotopic and chiral-isotopic imbalances has been investigated in the framework of the Nambu--Jona-Lasinio model. It has been established that chiral-isotopic imbalance could help promote of the pion condensation phase in isotopic imbalanced dense quark matter even at non-zero temperature.

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## Analytical description of nonlinear harmonic generation close to the saturation region in free electron lasers

### K. V. Zhukovsky

Moscow University Physics Bulletin 2019. N 5.

We perform phenomenological modelling of nonlinear harmonic generation in free electron laser (FEL) experiments. We model gradual saturation of the harmonic power and its evolution around the saturated regime. The model includes all major losses, accounted for each harmonic individually. This reflects the fact that the undulator radiation (UR) spectral line and the electron-wave interaction at high harmonic wavelengths is more sensitive to the losses, such as the beam energy spread, divergence etc. The results of the phenomenological modelling are compared with the experimental data and with numerical simulations. The proposed description of nonlinear harmonic generation appears in very good agreement with the FEL experiments SALCA, LEUTL, LCLS and other in various conditions. The results also match numerical simulations; differently from the latter, our model allows fast, still accurate modelling of FEL harmonic power and bunching evolution with a PC or even an engineering calculator. The model allows studying FEL radiation from undulators with arbitrary magnetic field configuration. With the help of the analytical FEL model we demonstrate that, contrary to the helical undulator, in whose spectrum the fundamental tone and the 2nd harmonic prevail, the FEL radiation from the elliptic undulator with the 3rd field harmonic has distinct 5th UR harmonic besides the fundamental, while other harmonics are negligible even close to the saturation length.

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## Solution of the inverse three-dimensional elastography problem for parametric classes of inclusions with a posteriori error estimate

### A. S. Leonov$^1$, A. N. Sharov$^2$, A. G. Yagola$^2$

Moscow University Physics Bulletin 2019. N 5.

This article presents the solution of a special three-dimensional inverse elastography problem: within the quasi-static model of a linear-elastic isotropic body under small surface compressions nds Young's modulus distribution in the investigated biological tissues using known vertical values of the displacements of tissues in it. A goal of this investigation is to detect local inclusions in tissue, interpreted as tumors and having Young's modulus values that are signicantly dierent from the known background value. Additionally, it is assumed that the Young's modulus is a constant function inside and outside of the required inclusions, the geometry of which is given parametrically. This inverse problem leads to the solution of a nonlinear operator equation, which by a variational method reduces to an extremal problem of nding the number of inclusions, the parameters dening their shape and the Young modulus for each inclusion. Algorithmically, the problem is solved using a modication of the method of extending compacts by V. K. Ivanov and I.N. Dombrovskaya. As an illustration of the algorithm, examples of solving model inverse problems with inclusions in the form of balls are given. For the found solution of one of the model problems a posteriori error estimate of the Young's modulus distribution is carried out.

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Condensed matter physics

## Structural and morphological studies under small-angle neutron scattering of tungsten alloys

### E. Demir, Yu. Gledenov, A. Tuğrul, M. N. Mirzayev, A. K. Islamov, V. A. Turchenko, O. Yılmaza, B. Bülent, E. Sansarbayar, M. Öveçoğlu

Moscow University Physics Bulletin 2019. N 5.

In the present work, W – 6 wt.% B4C – 2 wt.% TiC – 1 wt.% C powders were mechanical alloyed for 6 hours and sintered at 1750 oC for under N2, H2 gas flowing conditions in order to understand the structure and surface morphologies of the tungsten samples. Phase and microstructural characterization investigations of tungsten alloys were carried out using X-ray diffraction, scanning electron microscopy, small-angle neutron scattering, and Raman spectroscopy. Tungsten boron and tungsten boride as major phases were identified in the X-ray diffraction patterns. Raman spectra indicated the existence of the carbon phases, which are the disordered graphite (D) and graphite (C). Small-angle neutron scattering measurements were performed to obtain the distribution of powders. The results were in good agreement with scanning electron microscopy findings.

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Astronomy, astrophysics, and cosmology

## E-model α-attractor on brane from Planck data and reheating temperature

### F. Salamate, I. Khay, M. Ferricha-almi, H. Chakir, M. Bennai

Moscow University Physics Bulletin 2019. N 5.

In inflation sdandard scenario with α-attractors E-model, the infaltionary parameters determine by the e-fold number N and by the parameter α. Therefore, we study this model in the framework of the Randall--Sundrum type-II braneworld (RSII ). From the scalar curvature perturbation constrained by the recent observation values, and in the high-energy limit V>>λ, we can reduce the value range of the parameter α in order to render the inflationary parameters (n_{s}, r and ((dn_{s})/(dln k))) compatible with the latest Planck data. For the reheating epoch, we have computed and discussed the reheating temperature T_{reh} for several parameters, and it is large T_{reh}∼10¹³GeV.

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## Application of the nonparametric methods of mathematical statistics to search for cosmic strings

### A. V. Morgunova$^1$, O. S. Sazhina$^2$

Moscow University Physics Bulletin 2019. N 5.

A statistical study of the area, which according to the radio data of CMB anisotropy contains a candidate for the cosmic string (field CSc-1), was carried out in order to additional justification of this candidate. Cosmic strings are one-dimensional cosmological-scale objects, which may manifest itself in particular as a gravitational lenses with special features. It was solved the problem of statistical comparison of the distribution density of gravitational-lens pairs of sources (galaxies) in fields that do not contain cosmic strings with the distribution of similar pairs in the CSc-1 field. Nonparametric rank shift criteria were used to work with small samples under an unknown distribution law; the limits of applicability of the criteria were discussed. The revealed difference between the two distributions serves as an additional argument in favor of the presence of a string in the CSc-1 field. The discovery of cosmic strings would serve as a unique observational test of modern cosmological theories, including multidimensional models.

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Biophysics and medical physics

## Personal dose equivalent conversion coefficients skins dose for mono-energetic photons, electrons and positrons: Monte Carlo approach and development an analytical approach

### H. Al Kanti, T. EL BARDOUNI, O. EL HAJJAJI

Moscow University Physics Bulletin 2019. N 5.

The present work seeks to calculate and development of a new set of the personal dose equivalent conversion coefficients (Skins Dose) for mono-energetic photons (in absorbed dose and Kerma approximations), electrons and positrons from 10 keV to 10 MeV on the phantom ICRU tissue. The conversion coefficients calculations were two ways: Monte Carlo and development an analytical approach using FORTRAN program. The results obtained in this work were found to be in good agreement with to those published in joint report of ICRU and ICRP, 2017 [1]. The numerical comparison was made to validate DOSRZnrc code for conversion coefficients calculations as well as testing the developed of an analytical a new approach using FORTRAN. Our study can be useful to improve standards of protection for medical workers for procedure resulting in potentially high exposures and to develop methodologies for the best assessing and for reducing exposures.

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Engineering physics

## Modeling of the 2 MW TRIGA Mark-II research reactor using the deterministic codes system DRAGON5 and DONJON5

### O. Jai$^1$, O. EL HAJJAJI$^1$, T. EL BARDOUNI$^1$

Moscow University Physics Bulletin 2019. N 5.

This paper investigates the applicability of the DRAGON5 and DONJON5 code system to develop an accurate full-core model of the Moroccan 2 MW TRIGA Mark-II research reactor. The evaluated cross-section data library ENDFB.VII.1 with SHEM-295 group structure was used. A validation approach is applied to verify the consistency of the developed model. The results of the deterministic calculations based on ENDFB.VII.1/DRAGON5/DONJON5 scheme are compared with the experimental values available in the safety analysis report (SAR) as well as the Monte Carlo results. It was found that the DRAGON5 and DONJON5 code system results for core excess reactivity, critical size, reactivity worth of the five control rods, the power distribution and hot rod power peaking factor are in good agreement with measurements and the MCNP5 simulation values. Therefore, this study proves the capability of the DRAGON5 and DONJON5 code system to reliably simulate the TRIGA Type research reactors.

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## Peculiarities of sound propagation in shallow fresh water for different depths of sound source

### B. I. Goncharenko$^1$, A. I. Vedenev$^2$, A. S. Shurup$^3$

Moscow University Physics Bulletin 2019. N 5.

The results of experimental measurements of the scalar-vector characteristic of the acoustic field in a shallow water with carbonated bottom are analyzed. Simultaneous recording of sound pressure and three orthogonal components of particle velocity was carried out using a sound pressure receiver and a vector receiver. The source of the tone signal was a towed transducer; a noise signal from a passing ship was used as a source located near the water-air boundary. It is shown that in the spatial decrease of the sound field components, the significant variations in levels of sound pressure and particle velocity components are observed, regardless of the depth of the sound source. When the sound source is located at the depth of the water layer, the dependence of the spatial decrease of the acoustic field components is different, and when the noise signal source is located below the surface of the water-air interface, the character of the decreasing of sound pressure amplitudes and the vertical component of the particle velocity are the same throughout the measurement path.

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Chemical physics, physical kinetics, and plasma physics

## Localization of a pulsed volume discharge in a vortex zone behind a wedge in supersonic flow

### I. A. Znamenskaya, I. V. Mursenkova, D. S. Naumov, N. N. Sysoev

Moscow University Physics Bulletin 2019. N 5.

An experimental study of the development of a pulsed volume discharge with pre-ionization in a non-uniform supersonic air flow near the wedge in the shock tube channel and the gas-dynamic flow arising after the discharge has been carried out. Plasma configurations arising near the bottom of the wedge were studied when discharge initiating at various stages of unsteady flow. The conditions for the self-localization of a volume discharge into the vortex zone behind the wedge are analyzed at the Mach number of shock wave 2.6-3.5 (flow Mach number up to 1.50, density up to 0.15 kg / m3).

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