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Vol 72, No 5 (2017)

Astronomy, Astrophysics, and Cosmology (Review)

Randall–Sundrum II model from small field inflation in light of planck data and reheating temperature

Ferricha-Alami M., Mounzi Z., Jdair O., Naciri M., Bennai M., Chakir H.

Abstract

We focus on the behaviours of small field of an arctangent potential form, in Randall–Sundrum II braneworld. Within this framework, there is only one brane with positive tension while the second membrane is sent to infinity, and the configuration the model allows to localize the gravity on the curvature of the bulk. In that context, we found that inflationary observables (ns, r, and dns/dlnk) depend only on the e-folding number N. From the power perturbation value PR(k) given by the latest observational measurements, we evaluate the values of brane tension λ and the energy scale V0, and we have shown that the various inflationary perturbation parameters are widely consistent with the recent Planck data for a suitable choice of value of the number N. Concerning the reheating phase, we found a large value of the temperature Tre ∼ 5 × 1014 GeV.

Moscow University Physics Bulletin. 2017;72(5):425-432
pages 425-432 views

Theoretical and Mathematical Physics

The exponential parameterization of the neutrino mixing matrix as an SU(3) group element and an account for new experimental data

Zhukovsky K.V.

Abstract

The exponential form of the Pontecorvo–Maki–Nakagawa–Sakata mixing matrix for neutrinos is considered in the context of the fundamental representation of the SU(3) group. The logarithm of the mixing matrix is obtained. Based on the most recent experimental data on neutrino mixing, the exact values of the entries of the exponential matrix are calculated. The exact values for its real and imaginary parts are determined, respectively, in charge of the mixing without CP violation and of the pure CP violation effect. The hypothesis of complementarity for quarks and neutrinos is confirmed. The factorization of the exponential mixing matrix, which allows the separation of the mixing and of the CP violation itself in the form of the product of rotations around the real and imaginary axes, is demonstrated.

Moscow University Physics Bulletin. 2017;72(5):433-440
pages 433-440 views

The effect of the negative particle velocity in a soliton gas within Korteweg–de Vries-type equations

Shurgalina E.G., Pelinovsky E.N., Gorshkov K.A.

Abstract

The effect of changing the direction of motion of a defect (a soliton of small amplitude) in soliton lattices described by the Korteweg–de Vries and modified Korteweg–de Vries integrable equations (KdV and mKdV) was studied. Manifestation of this effect is possible as a result of the negative phase shift of a small soliton at the moment of nonlinear interaction with large solitons, as noted in [1], within the KdV equation. In the recent paper [2], an expression for the mean soliton velocity in a “cold” KdV-soliton gas has been found using kinetic theory, from which this effect also follows, but this fact has not been mentioned. In the present paper, we will show that the criterion of negative velocity is the same for both the KdV and mKdV equations and it can be obtained using simple kinematic considerations without applying kinetic theory. The averaged dynamics of the “smallest” soliton (defect) in a soliton gas consisting of solitons with random amplitudes has been investigated and the average criterion of changing the sign of the velocity has been derived and confirmed by numerical solutions of the KdV and mKdV equations.

Moscow University Physics Bulletin. 2017;72(5):441-448
pages 441-448 views

The intermittency of vector fields and random-number generators

Kalinin A.O., Sokoloff D.D., Tutubalin V.N.

Abstract

We examine how well natural random-number generators can reproduce the intermittency phenomena that arise in the transfer of vector fields in random media. A generator based on the analysis of financial indices is suggested as the most promising random-number generator. Is it shown that even this generator, however, fails to reproduce the phenomenon long enough to confidently detect intermittency, while the C++ generator successfully solves this problem. We discuss the prospects of using shell models of turbulence as the desired generator.

Moscow University Physics Bulletin. 2017;72(5):449-453
pages 449-453 views

Neutrino oscillations in a homogeneous moving medium

Lobanov A.E., Chukhnova A.V.

Abstract

The quasi-classical equation that describes both neutrino flavor oscillations and spin rotation in dense matter is obtained in the framework of quantum field theory. The solution of this equation for homogeneous medium is found. The probabilities of the spin-flavor transitions in unpolarized moving matter are calculated in the two-flavor model. We show that if the medium is at rest the neutrino helicity is conserved and the flavor transition probabilities are equal to those obtained using the phenomenological approach.

Moscow University Physics Bulletin. 2017;72(5):454-459
pages 454-459 views

Physics of Nuclei and Elementary Particles

Monte Carlo simulation of thermal neutron flux of americium–beryllium source used in neutron activation analysis

Didi A., Dadouch A., Bencheikh M., Jai O.

Abstract

The neutron activation analysis is a method of exclusively elemental analysis. Its implementation of irradiates the sample which can be analyzed by a high neutron flux, this method is widely used in developed countries with nuclear reactors or accelerators of particle. The purpose of this study is to develop a prototype to increase the neutron flux such as americium–beryllium and have the opportunity to produce radioisotopes. Americium–beryllium is a mobile source of neutron activity of 20 curie, and gives a thermal neutron flux of (1.8 ± 0.0007) × 106 n/cm2 s when using water as moderator, when using the paraffin, the thermal neutron flux increases to (2.2 ± 0.0008) × 106 n/cm2 s, in the case of adding two solid beryllium barriers, the distance between them is 24 cm, parallel and symmetrical about the source, the thermal flux is increased to (2.5 ± 0.0008) × 106 n/cm2 s and in the case of multi-source (6 sources), with-out barriers, increases to (1.17 ± 0.0008) × 107 n/cm2 s with a rate of increase equal to 4.3 and with the both barriers flux increased to (1.37 ± 0.0008) × 107 n/cm2 s.

Moscow University Physics Bulletin. 2017;72(5):460-464
pages 460-464 views

Modelisation and distribution of neutron flux in radium–beryllium source (226Ra–Be)

Didi A., Dadouch A., Jai O.

Abstract

Using the Monte Carlo N-Particle code (MCNP-6), to analyze the thermal, epithermal and fast neutron fluxes, of 3 millicuries of radium–beryllium, for determine the qualitative and quantitative of many materials, using method of neutron activation analysis. Radium–beryllium source of neutron is established to practical work and research in nuclear field. The main objective of this work was to enable us harness the profile flux of radium–beryllium irradiation, this theoretical study permits to discuss the design of the optimal irradiation and performance for increased the facility research and education of nuclear physics.

Moscow University Physics Bulletin. 2017;72(5):465-469
pages 465-469 views

Condensed Matter Physics

Investigation of the charge distribution in small cluster ions Ar13+ and Ar19+

Korobova J.G., Ieshkin A.E., Chernysh V.S.

Abstract

The results of ab initio studies of the atomic and charge structure of small clusters and cluster ions formed by 13 and 19 argon atoms are reported. It was found that the icosahedral atomic structure is energetically the most favorable for such clusters. The calculations demonstrate that when a single electron is removed from a cluster, the excess positive charge is distributed primarily over the surface of the formed cluster ion.

Moscow University Physics Bulletin. 2017;72(5):470-473
pages 470-473 views

Single-electron transistor with an island formed by several dopant phosphorus atoms

Dagesyan S.A., Shorokhov V.V., Presnov D.E., Soldatov E.S., Trifonov A.S., Krupenin V.A., Snigirev O.V.

Abstract

We present the results of an experimental study of electron transport through individual phosphorus dopants implanted into a silicon crystal. We developed an original technique for single-electron transistor fabrication from silicon-on-insulator material with an island formed by single phosphorus atoms. The proposed method is based on well-known CMOS compatible technological processes that are standard in semiconductor electronics and may be used in most research groups. The large Coulomb blockade energy value of the investigated single-electron transistor (∼20 meV) allows one to observe single-electron effects in a wide temperature range up to 77 K. We measured and analyzed stability diagrams of fabricated experimental structures. We demonstrated a single-electron transistor with controllable electron transport through two to three phosphorus dopants only.

Moscow University Physics Bulletin. 2017;72(5):474-479
pages 474-479 views

Chemical Physics, Physical Kinetics, and Plasma Physics

Simulation of shock-wave propagation in the argon plasma of a positive column discharge

Sukhov A.K.

Abstract

The computer simulation of shock-wave propagation in the argon plasma of positive column discharge was performed. A one-dimensional model of the gas-discharge plasma is used, which comprises the continuity equations for the electron and ion plasma components and the equation of electrostatics with allowance for initial and boundary conditions. The distribution of plasma parameters in the shock wave was obtained; the effect of its intensity was evaluated. The simulation results were compared with experimental data.

Moscow University Physics Bulletin. 2017;72(5):480-484
pages 480-484 views

Biophysics and Medical Physics

Hydrodynamic interaction of blood cells with micro-rough surfaces in a shear flow

Belyaev A.V.

Abstract

In this paper, we address hydrodynamic interactions of individual red blood cells (erythrocytes) with micro-rough surfaces in a shear flow of a viscous fluid using computer simulations. We study the influence of the microrelief on the dynamics of cell movement. It has been shown that periodic microrelief with typical length scale comparable with the size of an erythrocyte may cause an increase of the repulsive hydrodynamic force directed outwards on the micro-rough wall. The results can be used in the design of microfluidic devices that are intended to operate with whole blood samples.

Moscow University Physics Bulletin. 2017;72(5):485-490
pages 485-490 views

Erratum

Erratum to: “An optimization method for the calculation of Hamiltonian matrix elements for Josephson flux qubits”

Kuznetsov A.V., Klenov N.V.

Abstract

There is an additional material (see attachment).

Moscow University Physics Bulletin. 2017;72(5):491-491
pages 491-491 views