NANOSTRUTURES MATERIALS IN NUCLEAR ENERGETICS

N.A. Azarenkov, V.N. Vojevodin, V.G. Kirichenko, G.P. Kovtun

Full Text :   (5350 kB, Rus.) 

Abstract
The review of results of the investigations, researchers and using of nanomaterials in nuclear energetic and engineering are presented. The basic properties of nanostructure materials are adduced. The perspectives of nanomaterials applications in nuclear energetics which connected with creating of nanostructure materials and coating for constructive elements AES and future TNR for increasing of hardness and strength indices for increasing of corrosion and radiation stability are considered. Also the principal problems which arise under developing methods of nuclear fuel modification, under elaboration of strengthening oxide disperse steels and porous ceramics, frames, filters and membranes, elaboration of nanostructure conductors and superconductors and elaboration of nanostructure magnetic composites are considered.

KEY WORDS: nanomaterials, nanotechnology, nuclear fuel cycle, corrosion and radiation stability

NOT MONOTONIC DYNAMICS OF THE EXPANSION OF UNIVERSE IN SOME COSMOLOGICAL MODELS

D.A. Yerokhin, O.A. Lemets

Full Text :   (5350 kB, Rus.) 

Abstract
Recent observations of the Ia-type supernovae have shown that acceleration of the Universe expansion achieved its maximum value and now it starts decreasing. Such a scenario is incompatible with the generally accepted Standard cosmological model. The present work attempts to give an explanation to the phenomenon which is now called the transient acceleration. We considered two types of cosmological models: the first is a scalar field model and the second represents interacting dark matter and dark energy with necessary properties. We obtained dependencies of cosmological parameters on the scale factor for both the models.

KEY WORDS: expansion of Universe, transient acceleration, scalar field, interaction in dark sector, decay dark energy.

CRITICAL DIMENSION AND THE ABSENCE OF NON-PHYSICAL STATES IN TREE AMPLITUDES OF NSR STRINGS IN TENSORIAL SPACE

A.J. Nurmagambetov

Full Text :   (166 kB, Rus.) 

Abstract
We consider a method of calculating the critical dimension of a spinning string in tensorial space based on applying the Supersymmetric Conformal Field Theory (SCFT) technique. We calculate correlators of the matter and ghosts superfields under the superconformal gauge fixing, together with the standard energy-momentum tensors OPEs leading to the superconformal anomaly. The anomaly term is absent in spaces of dimensions D=4 and D=5. It is demonstrated that the standard set of conditions on physical states of the spectrum provides the decoupling of non-physical states in trees amplitudes of NSR tensorial strings in the bosonic limit.

KEY WORDS: spinning string, tensorial space, superconformal field theory

ISOMER RATIOS IN REACTIONS ⁹⁰Zr(γ,2np)^87m,gY END ⁹¹Zr(γ,3np)^87m,gY AT E_γMAX = 90 МEV

O.A. Bezshyyko, A.N. Vodin, L.O. Golinka-Bezshyyko, A.N. Dovbnya, I.M. Kadenko, О.A. Kivernik, V.A. Kushnir, V.V. Mitrochenko, S.N. Olejnik, I.A. Shapoval, A.V. Tertichnyi, G.E. Tuller

Full Text :   (290 kB, Rus.) 

Abstract
The results of measurements and calculations of isomeric ratios for the ^87m,gY nuclei, as products of the ⁹⁰Zr(γ,2np)^87m,gY and ⁹¹Zr(γ,3np)^87m,g photonuclear reactions, are presented in this work. The samples were irradiated by using bremsstrahlung of the electron linear accelerator LEA-40 with endpoint energy E_γmax = 84 MeV. The method of the induced activity measurement by a HPGe-detector was used to obtain experimental isomer ratios. The results were compared with calculations in the TALYS 1.0 code using statistical and pre- equilibrium modeling approaches.

KEY WORDS: isomer ratios, photonuclear reactions, neutrons, zirconium, TALYS

М1 TRANSITIONS BETWEEN BOUND STATES IN 2s1d-SHELL NUCLEI WITH DIFFERENT DEFORMATIONS

I.V. Ushakov, A.N. Vodin, G.K. Khomyakov

Full Text :   (165 kB, Rus.) 

Abstract
Calculations of М1 transition probabilities are performed within the Nilsson model for the cases with different deformations of the initial and final states of ²³Na and ³¹P nuclei. The results are compared with previous experimental data. This enabled to draw conclusions on the parameters of deformation of the investigated nuclei in excited states. Accounting of the different deformations of nuclei in the initial and final states could satisfactorily reconcile the calculated probability of М1 transitions with the experimental data.

KEY WORDS: bound state, γ-decay, М1 transition probability, Nilsson model, deformation parameter.

FAST CHARGED PARTICLES PASSAGE THROUGH A BENT CRYSTAL

N.F. Shul’ga, V.I. Truten’, I.V. Kirillin

Full Text :   (585 kB, Rus.) 

Abstract
Mechanisms of high energy charged particle beams deflection by bent crystals, connected with the phenomenon of plane channeling of particles, particles reflection from bent crystal atomic planes and multiple scattering on bent crystal atomic strings (stochastic mechanism) are considering. The program of computer simulation allowing from the uniform point of view to investigate these mechanisms of beams turning is developed. The comparative analysis of these turning mechanisms is carried out for positively and negatively charged particle beams. It is shown, that for negatively charged particles the most effective is the stochastic beams turning mechanism. For positively charged particles this mechanism results not only in a beam deflection on the wide angles, but also to splitting of a beam on several beams and to round beams transformation into flat beams. The comparison of simulation results with the results of CERN experiments of 2008- 2009 on detection of the stochastic mechanism of positively and negatively charged particle beams turn by the bent crystals is carried out.

KEY WORDS: bent crystal, turn of beam, ultrarelativistic particle, critical angle for axial channeling, critical angle for planar channeling.

INFLUENCE OF THE TRAPPED AND UNTRAPPED PARTICLES ON THE CHERENKOV WAVE DISSIPATION IN SPHERICAL TOKAMAKS

N.I. Grishanov

Full Text :   (455 kB, Rus.) 

Abstract
Untrapped (passing, circulating) and three of the trapped particles are described analytically in a toroidal plasma with D-shaped transverse cross-sections of the magnetic surfaces. Contributions of these particles to the longitudinal dielectric susceptibility elements are derived for radio-frequency waves in axisymmetric tokamaks under arbitrary aspect ratio, arbitrary elongation and small triangularity. The corresponding limits for the simpler plasma models are considered. Our dielectric characteristics are suitable to estimate the wave dissipation by electron Landau damping during the plasma heating and current drive generation in the frequency range of Alfv?n and fast magnetosonic waves, for both the large and low aspect ratio tokamaks with circular, elliptic and D-shaped magnetic surfaces. The dissipated wave power is expressed by the summation of terms including the imaginary parts of both the diagonal and non-diagonal elements of the parallel susceptibility.

KEY WORDS: trapped and untrapped particles, tokamaks, circular, elliptic and D-shaped cross-sections, longitudinal dielectric susceptibility, collisionless wave dissipation.

GAS BREAKDOWN IN THE DC ELECTRIC FIELD IN LONG DISCHARGE TUBES

V.A. Lisovskiy, V.A. Koval

Full Text :   (286 kB, Rus.) 

Abstract
In this work gas breakdown in homogeneous dc electric field in long discharge tubes is experimentally studied. Based on the experiments we made it is shown that the classical Paschen law for the gas breakdown in the dc electric field is valid only for the short discharge tubes, where the ratio of the discharge gap to the discharge tube radius dependence is L/R £ 1. For larger values of L/R the modified Paschen law U_dc = f (pL, L/R) should be used. If L/R > 1, then by increasing of the discharge gapL the dc breakdown curves U_dc(p) shift to the area of higher breakdown voltages U_dc and lower gas pressures. At the same time DC breakdown curves' minima at the plot U_dc (pL) take values at one straight line. It is shown that if L/R > 20, then increasing of the discharge gap L leads to shifting of the dc breakdown curves to the area of higher dc breakdown voltages U_dc. However their minima are observed almost at the unchanged gas pressure.

KEY WORDS: gas breakdown, discharge ignition, Paschen law, long discharge tubes.

MODELLING OF THE LOW PRESSURE GAS BREAKDOWN IN COMBINED ELECTRIC FIELDS

V.A. Lisovskiy, N.D. Kharchenko

Full Text :   (1535 kB, Rus.) 

Abstract
In this work measurements of the longitudinal combined discharge breakdown curves in the discharge chamber with a distance between the electrodes L = 32 mm were carried out. We also obtained an analytical gas breakdown criterion in the combined electric field with variable magnitudes of the RF and DC voltages. This criterion takes into account gas molecules ionization with the application of the RF and the DC electric fields at the same time, longitudinal and transverse electron diffusion, drift electrons and ions motion and ion induced electron emission from the cathode surface. The obtained criterion lets us investigate as the influence of the RF field to the DC breakdown as the influence of the DC field to the RF breakdown. The breakdown curves of the longitudinal combined discharge predicted by this criterion are in a good agreement with the experimental data.

KEY WORDS: combined discharge, RF capacitive discharge, DC discharge, discharge ignition, low pressure gas breakdown, modeling, argon.

INFLUENSE OF SHOCK -WAVE TREATMENT ON SURFACE OF STEEL 38ХНЗМФА

V.G. Kirichenko, Т.А. Kovalenko, V.N. Leonov

Full Text :   (875 kB, Rus.) 

Abstract
The results of research of structure - phase transformations and hardening of 38ХНЗМФА steel after shock - wave are presented. Shock - wave treatment of a steel 38ХНЗМФА leads to augmentation of strength of the samples, caused by processes of redistribution of phases and carbon in surface layers. Hardening of steel at shock - wave treatment is caused by allocation in a martensite matrix cementite phases.

KEY WORDS: shock action, ferrite steels, phase transformations, strengthening, martensite, cementite

RESERCH OF MECHANICAL CHARACTERISTIC OF NANOCOMPOSITE COMBINED TI-CR-N/NI-CR-FE-SI-B COATINGS

А.А. Drobyshevskaya, V.М. Beresnev, А.D. Pogrebnjak

Full Text :   (1653 kB, Rus.) 

Abstract
In the article the results of investigation of mechanical properties and corrosion resistance of Ti-Cr-N/Ni-Cr-Fe-Si-B coatings obtained by combination of vacuum-arc deposition and plasma- detonation technology are presented. For analysis of mechanical properties the tests of hardness by a method nanoindentation, and also tests for wearing, corrosion stability in different mediums and adhesion were carried out. Reducing of wear is shown at friction of cylinder on a plane almost on the order, increase of hardness and corrosion stability in a hostile environment.

KEY WORDS: combined coating, hardness, corrosion resistance.

ELECTRORESISTANCE PROPERTIES OF Nb_1-xSe₂Sn_x SINGLE CRYSTALS: EFFECT OF HIGH PRESSURE AND DOPING BY TIN

О.В. Samoylov, D.D. Balla, A.A. Zavgorodniy, R.V. Vovk, M.A. Obolenskiy

Full Text :   (457 kB, Ukr.) 

Abstract
In present work effect of hydrostatical pressure up to 12 кбар on the critical parameters of Nb_1-xSe₂Sn_x single crystals (х=0,1 and х=0,15) are investigated. It is shown that a basic contribution to the Tc increasing constraint makes alteration to the closeness of the states at the Fermi level. It is determined that under hydrostatical pressure a phonon spectrum is displaced toward high-frequencies (toughening of spectrum). The numeral estimation of the Debye temperature comports with by information, got by measuring of heat capacity of NbSe₂ single crystals. It is rotined that with the increase of hydrostatical pressure mean free path increases and Nb_1-xSe₂Sn_x can examine in a clean limit in the Ginzburga-Landau theory.

KEY WORDS: superconductivity, doping, NbSe₂, single crystals, hydrostatical pressure, mean free path.

XPS STUDY OF TiN_xO_y NANOSCALED FILMS, FORMED BY ION BEAM SPUTTER DEPOSITION

A.M. Styervoyedov, V.M. Beresnev

Full Text :   (812 kB, Rus.) 

Abstract
The results of studies using X-ray photoelectron spectroscopy of nanoscaled films TiN_xO_y thickness of about 5 nm, obtained on silicon by low-current ion beam sputtering are presented in given work. Also it is shown the possibility of using angle-resolved XPS to determine the thickness and continuity of the obtained ultra-thin films. The effect of substrate temperature during ion beam synthesis and thermal annealing on the chemical state and the diffusion properties of the structures Ti-O-N/Si is shown in details.

KEY WORDS: nanoscaled films, titanium oxinitride, ion beam sputtering, X-ray photoelectron spectroscopy, XPS.

STUDY OF CHARGE CAPTURE IN CdZnTe GAMMA-RAY DOSIMETRY DETECTORS

D.V. Nakonechny, A.A. Zakharchenko, V.E. Kutny, A.V. Rybka, M.A. Khazhmuradov

Full Text :   (978 kB, Rus.) 

Abstract
The dependence of the spectral lines width on charge carriers losses in CdZnTe gamma-ray detectors was studied. A set of planar CdZnTe detectors tailored of ingots, grown by HPBM method, was investigated. Is was found, that at energies greater than 60 keV the effect of charge capture on the photopeak width is directly proportional to an average charge created at absorption of gamma quantum in the detector material. As a result a conclusion was drawn, that the most probable reason of strong capture of holes is the presence of significant concentration of Cd vacancies and/or of complexes of Cd vacancy and donor impurity.

KEY WORDS: CdZnTe, detector, nonequilibrium charge, charge capture, gamma-rays, FWHM.

DETERMINATION OF DISLOCATIONS DENSITY ON ANALYSIS OF MYCROSTRAINS IN POLYCRYSTALLINE MATERIALS

D.G. Malykhin, V.V. Kornyeyeva

Full Text :   (435 kB, Rus.) 

Abstract
An analysis of a pattern of X-ray diffraction on edge dislocations and techniques proposed earlier for analysis of dislocations structure in materials on primary parameters of Voigt function model of X-ray line shape is carried out. It is noted that accuracy of edge dislocations density calculations is considerably depended on character of its distribution and methods of averaging of characteristics. Line shape of diffraction on edge dislocations areas in linear approach of diffraction is built with taking into account of its random distribution. On base of it a more exact value of primary parameter of X-ray lines shape which is using in Voigt model at calculation of dislocations density is determined.

KEY WORDS: X-ray analysis, diffraction, strains, dislocations, pattern, calculation, approximation, Voigt function, Cauchy function, dislocations density

THE HIGH-SENSITIVITY INDUCTION BUNCH CURRENT GAUGE OF THE HEAVY IONS LINAC

A.F. Dyachenko

Full Text :   (960 kB, Rus.) 

Abstract
The basic measurement techniques of the accelerator bunch current: contact, high-frequency and induction methods are considered. The suitable, exact and most widespread bunch current measuring method is based on use of an electromagnetic induction effect. Usually it is the toroidal core from ferrite or thin-sheet magnetic alloy (permalloy) on which the winding is reeled up. The induction gauge is easily graduated by means of calibration coil on which the known current is passed. Use of the core from amorphous nanocrystal alloy which magnetic permeability reaches several tens thousand and modern noise-immunity electronic schemes has allowed to develop the high-sensitivity induction flying bunch current gauge of the heavy ions linac (the bottom limit of a measured current 1 μА).

KEY WORDS: induction gauge, heavy ions linac, bunch current, electronic schemes.

EXPERIMENTAL BENCHMARKING OF SOFTWARE MODESTEB FOR SIMULATION ELECTRON BEAM PROCESSING

V.T. Lazurik, V.M. Lazurik, G.F. Popov, Y.V. Rogov, I. Kaluska, Z. Zimek

Full Text :   (1170 kB) 

Abstract
Introduction success of radiation technologies into practice substantially depends on development of computational dosimetry which is based on accurate and validated programs, capable effectively calculate absorbed dose in processes of an irradiation. The simulation of the absorbed dose distributions into thin polyvinylchloride dosimetric films located in the stack of plates of a reference materials irradiated with a scanned electron beam was performed. Modeling of electron beam dose distributions in the multi-layer packages was accomplished using the Monte Carlo method in a three-dimensional geometrical model with utilization of the software ModeStEB. Results of benchmarking experiment for the software ModeStEB, which is used for simulation of industrial electron beam processing, are considered.

KEY WORDS: computational dosimetry, Monte Carlo method, software ModeStEB, dose distribution

NUMERICAL SIMULATION OF EXCITATION OF WAKEFIELD BUBBLE OF PLASMA ELECTRONS BY SHORT DENSE BUNCH OF RELATIVISTIC ELECTRONS

V.I. Maslov, I.N. Onishchenko, O.M. Svystun

Full Text :   (1458 kB) 

Abstract
The numerical simulation by 2.5D code LCODE of properties and excitation of wakefield bubble of plasma electrons by short dense bunch of relativistic electrons has been performed in this paper. It has been shown that abrupt back front of bubble becomes less abrupt at decrease of bunch-driver length. Abrupt back front of bubble becomes more abrupt at increase of bunch- driver current. At bubble excitation by short electron bunch with not very large density bubble can be formed in the second wavelength and bubble is not formed in the first wavelength. At larger bunch density the bubble is not formed in the first wavelength on small time and it can be formed on large time. The bunch focusing by bubble becomes more homogeneous with growth of bunch current.

KEY WORDS: laser pulse, wakefield bubble, relativistic electron bunch, numerical simulation.

ABOUT MISTAKES AT CALCULATING THE CHARGES SYSTEM ANGULAR MOMENTUM IN THE CONSTANT ELECTROMAGNETIC FIELD

Yu.A. Kirochkin, A.Yu. Kirochkin

Full Text :   (333 kB, Rus.) 

Abstract
In all editions of «Field Theory» of L.D. Landau and E.M. Lifshits when proving the Larmor theorem the Lagrangian function of nonrelativistic charges system with the same charge-to- mass ratio executing a finite motion in constant central-symmetric electric and homogeneous magnetic fields is used. When transforming to the coordinate system rotating with Larmor's frequency transformed Lagrangian function differs from the source only by the absence of term proportional to the magnetic field. Then it is stated that this Larmor's precession of angular momentum (and magnetic moment) of the considered charges system can be explained also by means of moment equation averaging of times small as compared to inverse Larmor's frequency. But in «Field Theory» when transforming the moment of Lorentz force a term being a total time derivative is neglected. In this paper it is shown that this term cannot be neglected.

KEY WORDS: angular momentum, magnetic moment, magnetic field, Larmor's frequency, diamagnetism