RADIATION HARDNESS OF SEMICONDUCTOR DETECTORS FOR CORPUSCULAR AND GAMMA-RADIATION

L.N. Davydov, A.A. Zakharchenko, D.V. Kutny, V.E. Kutny, I.M. Neklyudov, A.V. Rybka, I.N. Shlyakhov

Full Text :   (190 kB, Rus.) 

Abstract
During its operation an X-ray or γ-ray semiconductor detector is intrinsically subjected to radiation damage, which deteriorates the device characteristics and can cause its failure. The radiation damage in γ-ray dosimeter semiconductor detectors degrades their count characteristics. In spectroscopy semiconductor detectors the energy resolution aggravates, the leakage current increases, and the position of the photopeak shifts to smaller energy values. In this review the current level of understanding of the semiconductor detectors radiation degradation is described and some available methods of detector service-life prolongation are pointed out. The information about radiation hardness of silicon detectors as the most investigated, and of wide-zone semiconductor detectors, recently widely applied, such as CVD diamond, CdTe and CdZnTe, is given. The researches of radiation service-life of dosimetry and spectrometry detectors from CdTe and CdZnTe, carried out in NSC KIPT, are described. The obtained count characteristics and ¹³⁷Cs pulse spectra are indicated as functions of an absorbed doze of gamma-radiation. It is shown, that the detectors from CdTe and CdZnTe have increased radiation hardness compared to conventional silicon detectors. The spectrometry detectors conserve the ability to discriminate the gamma-radiation energy up to the absorbed dose about 20 kGy, and the dosimetry detectors continue to register the dose up to several hundreds of kGy.

KEY WORDS: radiation damage, semiconductor detector, γ-rays, particle irradiation, silicon, CdTe, CdZnTe.

CONSTANT SOLUTIONS OF QUANTUM YANG-BAXTER EQUATION OVER GRASSMANN ALGEBRA

S.A. Duplij, O.I. Kotulska, A.S. Sadovnikov

Full Text :   (390 kB, Rus.) 

Abstract
Constant solutions to Yang-Baxter equation are investigated for the case of 6-vertex R-matrix which appears in desription of exactly solvable models, quantum plane and special quantum gates. The general classification of all possible sulutions over Grassmann algebra and particular cases are studied. As distinct from the standard case, when R-matrix can have only 5 elements, we obtained full 6-vertex solution. The solutions leading to regular R-matrices which appear in weak Hopf algebras are considered.

KEY WORDS: constant solution, Grassmann algebra, quantum gate, regularity, R-matrix.

ON THE THEORY OF ELECTRON MULTIPACTING IN A VACUUM CELL OF LINEAR ACCELERATOR

L.D. Lobzov, A.P. Tolstoluzhsky, N.G. Shulika

Full Text :   (460 kB, Rus.) 

Abstract
Some operation peculiarities of the vacuum charged accelerator structure are caused by resonant secondary-electron process emission and bombardment of parallel parts of electrode surfaces in diode gaps forming structure electrical fields. At the accelerated electron energies defined, and values of secondary emission factors, that may reduce to intensive electron fluxes, disturbing accelerator operation. In this case reactive and active parameters of structures and their gaps not only, but also amplitude phase performance of their electrical fields influencing on the general character of the secondary electron process behavior. On the model of the parallel oscillating contour similar to the vacuum accelerator cell, perturbative by multipacting, the resonant movement of secondary emitting electrons in the diode gap has been considered theoretically. It's shown, that electron multipacting may exist in increasing and lowering electrical fields. Limiting values of high qualities loaded by secondary electron emission of the accelerating structure cell characterizing limit rates of voltage changes (variations) to suppress electron multipacting are indicated.

KEY WORDS: linear accelerator, vacuum accelerating cell, electrical sparking, vacuum multipacting.

EXPERIMENTAL AND NUMERICAL STUDIES OF CARBON FILM EFFECT ON THE OPTICAL PROPERTIES OF METALLIC MIRRORS

V.N. Bondarenko, A.I. Belyaeva, V.S. Voitsenya, A.A. Galuza, V.G. Konovalov, D.I. Naidenkova, A.N. Shapoval, A.F. Shtan', S.I. Solodovchenko

Full Text :   (450 kB, Rus.) 

Abstract
The transport of erosion material inside the fusion device vacuum chamber and its deposition onto surfaces being remote from confined plasma is one of reasons of the deterioration of in-vessel diagnostic mirrors. The main component in the deposit is carbon because graphite is used as a protection material of vessel walls and divertor plates. In order to study the effects associated with mirrors contamination, the model experiments were carried out with a-C films deposited on stainless steel mirrors in operating Large Helical Device (LHD), and Mo mirrors and glass plates in special stands. After mirrors had been extracted from devices, their reflection power values were gradually restored inside the stand in IPP NSC KIPT under the impact of deuterium plasma ions. The optical constants of films (n and k) at a wavelength of λ=632.8 nm and film thickness were determined by the methods of ellipsometry. The spectral reflectance of mirrors and glass plates with a-C film was measured at normal incidence. The dynamics of all parameters was obtained during the film removal. The satisfactory fittings to the measured reflectance of tested mirrors were found by a programmed selection from a database of n(λ) and k(λ) indices of carbon-based films.

KEY WORDS: in-vessel diagnostic mirrors, carbon-based films, restoration of optical characteristics, deuterium plasma, ellipsometry data of films.

DETERMINATION OF MAXIMUM ENERGY OF ACCELERATED PARTICLES IN JET KNOTS OF EXTRA GALAXY SOURCES

E.Yu. Bannikova

Full Text :   (360 kB, Rus.) 

Abstract
The high frequency break of synchrotron spectra of extra galaxy sources (radio galaxies and quasars) corresponds to the maximal value of energy of the accelerated particles connected to local places of acceleration of relativistic electrons in jet «knots» or «hot spots». Investigation of thin radio structure of such sources in the high-frequency break region can give the additional information on mechanisms of acceleration and on character of the spectrum of injected particles. In this work in the frameworks of the diffusion models the dependence of maps and spectra of synchrotron radiation on the kind of the spectrum of the injected particles in the region of maximal energy is considered. It is also shown that in the frequency region where the synchrotron radiation disappears and if radiation due to inverse Compton scattering is small enough, by sufficient instrument sensitivity it becomes possible to determine the thermal plasma jet parameters.

KEY WORDS: jet, radio galaxy, quasar, knots, hot spots, shock waves, particle acceleration, synchrotron radiation.

STUDIES OF PROCESSES TAKING PLACE AT SIMS ANALYSIS IN GLYCEROL SOLUTIONS OF ORGANIC DYES

V.N. Melnykov, V.A. Litvinov, V.T. Koppe, V.V. Bobkov, V.V. Tovstyak

Full Text :   (270 kB, Rus.) 

Abstract
The work is devoted to investigations of changing of molecule concentration of solute substance in glycerol matrix in result of processes going under a bombardment of sample-solutions by primary ions at secondary ion mass-spectrometry. The objects of investigations were solutions in glycerol of organic dyes: rhodamine 6G, neutral red, methylene blue, phenol red, methyl orange. It was shown that the molecule concentration of solute substance in near surface layer of glycerol matrix had been formed as a result of competition of processes: destruction of molecules by primary ions during the analysis and renewal of this layer with undamaged molecules diffusing from the solution bulk. Even at the ion current density Ar+ about 0.3 mkA/cm² lowering of equilibrium concentration of molecules of solute substance in near surface layer of a sample was noted, that should be taken into account at secondary ion mass- spectrometry.

KEY WORDS: secondary ion mass-spectrometry, glycerol matrix, ion bombardment influence, organic dyes.

RESONANCE PHENOMENA OF CHARGED PARTICLE MOTION IN AMBIPOLAR ELECTRIC FIELD AND HELICAL MAGNETIC FIELD OF A TOROIDAL TRAP

S.V. Vlasova, A.A. Shishkin

Full Text :   (230 kB, Rus.) 

Abstract
The resonance splitting of the particle drift surface is found in the case when the ambipolar electric field and helical magnetic field are taken into account. The helical magnetic field is considered to be the "perturbing force". The coordinates of the singular points are evaluated, which can show the deviation of the particle orbit from the initial magnetic surface.

KEY WORDS: passing particle, resonance, ambipolar electric field, helical magnetic field, resonance splitting, drift surface.

COMPUTER SIMULATION OF FILMS DEPOSITION UNDER SUFFICIENT SURFACE DIFFUSION

I.G. Marchenko

Full Text :   (700 kB, Rus.) 

Abstract
The processes of microstructure formation of thin niobium films at temperature 800K were investigated by molecular dynamics method. The obtained results compared with those at low temperature deposition. It is shown that temperature increasing lead to decreasing of microcracks arise probability and increasing of nanoblocs size.

KEY WORDS: films, vacuum deposition, computer simulation, niobium, molecular dynamics method, surface thermal diffusion, nanostructure.

THE DISTRIBUTION DENSITY MONITORING OF THE ELECTRON BEAM IN AIR

N.I. Ayzatsky, V.N.Boriskin, V.A.Gurin, A.N.Savchenko, A.A.Sarvilov, V.I.Tatanov

Full Text :   (290 kB, Rus.) 

Abstract
The method of measurement of two-dimension distribution density in electron beam by secondary emission monitor is developed. The monitor work with electron beams of energy up to 12 MeV and of pulse currents up to 1 A is researched. The beam cross-sections were measured at different angles of monitor turn. The probability was demonstrated to use obtained data for reconstruction of two-dimension distribution density in electron beam by computer tomography method.

KEY WORDS: electron beam, monitor, secondary emission, computer tomography.

MEAN ENERGY OF ELECTRONS EMITTED FROM SOLIDS UNDER SWIFT LIGHT ION BOMBARDMENT

N.V. Sydorenko, S.I. Kononenko, V.P. Zhurenko

Full Text :   (170 kB, Eng.) 

Abstract
In this paper energy distributions of secondary electron emission induced by 1-2.5 MeV H⁺ and He⁺ ions from GaAs, CdTe, Ge and Ti samples were analyzed. Dependences of mean electron energy on electronic stopping power of ions in the substances were obtained. The semiconductors had small dependence of mean electron energy in the range of ion energy being investigated. Mean electron energy decreased with growth of electronic stopping power of ion for titanium sample. We concluded that the semiconductors would be more preferable materials in comparison with titanium to use as emitting layers in the secondary emission radioisotope current source.

KEY WORDS: secondary electron emission, energy distribution function of electrons, mean electron energy, electronic stopping power of ions.

X-RAY PHOTOELECTRON SPECTROSCOPY OF ULTRA THIN TITANIUM AND TITANIUM NITRIDE FILMS, OBTAINED BY ION BEAM SPUTTER DEPOSITION

A.N. Styervoyedov, V.I. Farenik

Full Text :   (240 kB, Rus.) 

Abstract
The results of investigations of ultra thin titanium and titanium nitride films on silicon, obtained by ion beam sputtering of titanium target both in vacuum and nitrogen atmosphere, using argon ions with energy of 5 keV and target current about 15 mkA are presented in this paper. Elemental composition and chemical state of obtained films were investigated by x-ray photoelectron spectroscopy with using of Mg-Kα x-ray radiation (photon energy hν=1253.6 eV). Reviewed photoelectron spectrums of samples surface, obtained in different steps of films synthesis, detailed spectrums of photoelectron emission from Si2p, Ti2p, N1s core levels and also x-ray photoelectron spectrums of Auger electron emission are presented.

KEY WORDS: titanium, titanium nitride, ultra thin films, ion beam sputtering, X-ray photoelectron spectroscopy, XPS.

GAS-DYNAMIC EXPANTION OF SPARK CHANNEL UPTO MOMENT OF A SHOCK WAVE FORMATION

K.V. Korytchenko

Full Text :   (380 kB, Rus.) 

Abstract
Mathematical modeling of a gas-dynamic expansion until a shock wave formation has been made to a spark in dependence on a electron density distribution in a cross direction to axis of a discharge channel. Conditions of the electron density distribution which are supplying of a conductor increase into a discharge channel due to an ionization by an electron hit or a thermal ionization has been revealed. A reason of a current redistribution at a cross section of a discharge channel has been found out.

KEY WORDS: spark discharge, shock wave, current, electron impact ionization, thermal ionization, channel.

A BOLOMETRIC SENSOR FOR RADIATION LOSS MEASUREMENTS IN THE URAGAN-3M TORSATPON

V.I. Kovalenko, V.D. Kotsubanov, I.K. Nikol’skii, F.I. Ozherel’yev, S.A. Tsybenko

Full Text :   (250 kB, Rus.) 

Abstract
With the account of specifics of Uragan-3M (U-3M) torsatron operation, a thermoprobe type sensor has been chosen for bolometric measurements. The sensor is installed on the plasma facing surface of an U-3M magnetic pole, the minimum height of the apparatus being 28 mm. As a working body, a 3 μm titanium foil heated up to 1100°K is used. The maximum reception angle of plasma radiation is 155°. The foil is heated by a 5 s long rectangular current pulse. The calibration of the bolometer is made by superposition of an additional rectangular 1÷40 ms long heating current pulse. A suppression of the ~ 8.5 MHz interference produced by the plasma heating oscillator is 55 dB. A reduction of the useful signal pedestal is 60 dB. The temporal resolution of the system is 10^-3 s, the minimum level of the recorded signal corresponds to the power of ~ 10 kW radiated by the plasma.

KEY WORDS: plasma, torsatron, radiation losses, bolometry.

QUANTUM INFORMATION, QUBITS AND QUANTUM ALGORITHMS

S.A. Duplij, V.V. Kalashnikov, E.A. Maslov

Full Text :   (210 kB, Rus.) 

Abstract
The main ideas and notions of quantum information theory and principles of quantum computing, which are basic in quantum computers, are reviewed. Various proprerties of qubits and their generalizations are considered. Some quantum computing algorithms are explored and their peculiarities which differ them from correspondent classical algorithms are presented.

KEY WORDS: quantum computer, quantum gate, qubit, register, qubit field theory.

QUANTUM GROUPS AND NON-COMMUTATIVE COMPLEX ANALYSIS

S.D. Sinel’shchikov, L.L. Vaksman

Full Text :   (180 kB, Eng.) 

Abstract
Non-commutative analogues of function algebras on the unit ball are considered in the context of quantum group theory. The maximum principle for holomorphic functions in the quantum ball is expounded. An invariant integral on the quantum analogue of function algebra on sphere is used to produce a faithful *-representation of the latter C*-algebra. The Shilov boundary for the quantum analogue of the algebra of holomorphic functions is described.

KEY WORDS: quantum unit ball, C*-algebra, completely isometric map, invariant integral, the Shilov boundary.

INTEGRABLE STRING MODELS OF HYDRODYNAMICAL TYPE

V.D. Gershun

Full Text :   (200 kB, Eng.) 

Abstract
The closed string model of hydrodynamical type is considered as a bi-Hamiltonian system. Nonlocal Poisson brackets were used to construct nonlinear integrable string models, which are not models of sigma-model type. The recursion operator was obtained. Second string Hamiltonian was obtained.

KEY WORDS: string model, integrable model, nonlocal brackets, hydrodynamical type model.

ABOUT QUANTUM KINEMATICS AND DYNAMICS ON SUPERSPACE WITHIN THE FRAMEWORK OF SCHWINGER’S APPROACH

I.G. Kharin

Full Text :   (140 kB, Rus.) 

Abstract
We show that in the frameworks of Schwinger's formulation of quantum kinematics and dynamics naturally there is a concept of superspace. Within the frameworks of this approach the algebraic similitude of the manipulation with variables of various parity, the algebraic definition of the differentiation operation results in simplification of a conclusion of many important results of the superanalysis. In particular in this paper using this approach we deduce the formula for the superdeterminant basing on the concept of delta - function on the space of even and odd variables.

KEY WORDS: quantum dynamics, even and odd variables, supergroup, superspace, superdeterminant.