DOSE FIELD FORMATION IN THIN FILMS IRRADIATED BY ELECTRON BEAMS: COMPARISON OF THE MONTE CARLO SIMULATION WITH DOSIMETRY

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

Full Text :   (420 kB) 

Abstract
The simulation of the absorbed dose distribution into thin films with different thickness inserted between flat boundaries of two homogeneous materials as well as the absorbed dose distribution near to boundaries of these materials irradiated with a scanned electron beam were fulfilled. Films inserted in multi-layer targets were parallel orientated with an incident electron beam (EB). The simulation was performed by the Monte Carlo (MC) method with utilization of the software ModePEB which was designed for predictions of a dose distribution in heterogeneous targets irradiated by EB with the electron energy range from 0.1 to 25 MeV. Comparison results of MC simulation with dosimetry for electron dose distribution formation in multi-layer targets with thin films is discussed.

KEY WORDS: dose distribution, thin films, electron beam, software ModePEB.

VALIDITY OF IDENTIFICATION OF MULTIDOT EVENTS IN A PROPORTIONAL COUNTER OF LARGE VOLUME IN THE EXPERIMENTAL SEARCH OF 2K-CAPTURE

S.I. Panasenko, S.S. Ratkevich

Full Text :   (915 kB, Rus.) 

Abstract
The possibility of identification of multidot event is observationally shown at simultaneous recording characteristic quantum and Auger-electrons in large low-background the single-wire cylindrical counter of a high pressure. The analysis algorithm of a pulse shape and a method of inhibition the noise components of current signals from the counter used in experiments on search of 2K-capture in isotopes of noble gases 78Kr and 124Хе presented. Both the technique of separation of single- and multi-point events and the method to identify the multiple energy deposits use the timing information of the electrical response of the detector. Using the Daubechies' wavelets in multiresolutional wavelet analysis of signals allows us to increase energy resolution and efficiency of extraction of multi-point events from single-point dominated samples in the detector by 3-4 times.

KEY WORDS: proportional counter, double beta decay, 2K- capture decay mode, pulse shape analysis, Daubechies wavelet.

IONIZATION CHAMBER DIAGNOSTICS OF ELECTRON BEAM PARAMETERS IN RADIOTECHNOLOGIES

S.P. Gokov, O.A. Demeshko, V.I. Kasilov, S.S. Kochetov, L.A. Makhnenko, I.V. Mel’nitsky, O.A. Shopen

Full Text :   (380 kB, Rus.) 

Abstract
The paper deals with the characteristics of a parallel-plate ionization chamber used as a sensor of the system of electron beam diagnostics at the radiation test bench of the electron linear accelerator LINAC-300. Possibilities are demonstrated for determining the Gaussian electron flux profile in the plane of the object, as well as for performing the initial beam adjustment and beam position monitoring in the process of irradiation. Considerations are given on the possibility of using the chamber in the automated dose-monitoring system at the test bench.

KEY WORDS: linear accelerator, ionization chamber, electron beam, accelerating potential, lamellar sensor.

ABSORBED DOSE DETERMINATION ON ELECTRON IRRADIATION OF INHOMOGENEOUS OBJECTS

S.P. Gokov, O.A. Demeshko, V.I. Kasilov, S.S. Kochetov, L.A. Makhnenko, I.V. Mel’nitsky, O.A. Shopen

Full Text :   (373 kB, Rus.) 

Abstract
The present paper is complementary to our previous investigations on the analytical maintenance of radiation technologies introduced at the accelerator LINAC-300. Here a more detailed consideration is given to the problem of determining the surface/depth doses absorbed during fast electron irradiation of density-nonuniform objects. In this connection, technical peculiarities of the accelerator's radiation test bench are taken into account, including the beam nonorthogonality and the Gaussian distribution of electron flux density in the cross section. The process of electron passage through the object matter under study and the depth dose formation have been simulated by using the packaged programs PENELOPE based on the Monte-Carlo technique. The comparison between calculated and experimental data, performed in the work, has shown that the divergence between the absorbed doses measured at the most characteristic points of the samples under study is not higher than ~ 20% at simulation and ~ 30% in calculations.

KEY WORDS: linear accelerator, absorbed dose, electron beam, Gaussian distribution of beam, radiation test bench, bilateral irradiation.

PHOTOEXCITATION OF THE ^117MSn BY (γ,γ') REACTION AT E_γ< 3 MEV

O.S. Shevchenko, Yu.М. Ranyuk, A.M. Dovbnya, E.L. Kuplennikov, V.Yu. Ponomarev

Full Text :   (283 kB, Rus.) 

Abstract
New data on photoexcitation of nuclear isomer ^117mSn were received by a beam of electrons of electrostatic electron accelerator. The yield of the isomeric state ^117mSn with excitation energy E_iso = 314.58 keV has been measured in ¹¹⁷Sn(γ,γ')^117mSn reaction by activation method with the bremsstrahlung end-point energy from 2.1 to 3.0 MeV. In this energy range only one intermediate state (IS) responsible for the isomer feeding has been found. The excitation energy of the IS (2.25 ± 0.05) MeV and photoproduction integral cross section (0.022 ± 0.002) еV×b.

KEY WORDS: lead, isotopes, bremsstrahlung spectra, end-point energy, photoexcitation, photoactivation method, isomeric state, integral cross section, quasiparticle-phonon model.

SOME QUESTIONS OF USE OF THE ELECTRON ACCELERATOR AS THE DRIVER OF THE SUBCRITICAL ASSEMBLY

V.V. Gann, A.N. Dovbnya, I.S. Guk, A.I. Kalinichenko, S.G. Kononenko, A.S. Tarasenko

Full Text :   (300 kB, Rus.) 

Abstract
The state of research of electron beam interaction with subcritical assemblies is considered. Parameters of the electron accelerators used in experiments are given. In view of increase of estimated capacity of electron beams up to 100 kW, the outlet windows of accelerators and construction of a neutron-generating target will be subjected to the most loading. The thermoacoustic stress excitation by powerful electron beam passing through construction materials is one of important mechanisms of fracture. Estimates of influence of thermoacoustic stress on fastness of devices of subcritical assembly converters are spent.

KEY WORDS: electron beam, subcritical accembly, aluminum, tungsten, uranium, recurrence rate, thermoacoustic vibrations, strength threshold.

VACUUM SYSTEM OF INJECTION CHANNAL FOR STORAGE RING NESTOR

A.N. Gordienko, V.G. Grevtsev, O.D. Zvonaryova, A.Yu. Zelinsky, I.I. Karnaukhov, V.P. Kozin, N.I. Mocheshnikov, F.A. Peev

Full Text :   (230 kB, Rus.) 

Abstract
The scheme of differential pumping was calculated to provide residual gas pressure decreasing from a linear accelerator 10^-7 Torr to 10^-9 Torr in a storage ring of X-ray source NESTOR. Such value of dynamic pressure of the residual gas in presence of electron beam and its synchrotron radiation provides value of beam lifetime of about 2 hours at the electron beam energy 250 MeV.

KEY WORDS: ultrahigh vacuum, life time of electron beam, electrons storage ring, without oil vacuum pumps, differential pumping.

VLASOV EQUATION FOR MAGNETIZED PLASMA PARTICLES IN THE ARBITRARY MAGNETIC FIELD

N.I. Grishanov

Full Text :   (243 kB) 

Abstract
The linearized Vlasov equation is rewritten for charged particles in the two-dimensional axisymmetric plasma models using the cylindrical coordinates. There is described a method of its solution by the Fourier expansions of the perturbed distribution functions over the gyrophase angle in velocity space, conservation integrals of particle motion in the curvilinear magnetic field and smallness of the magnetization parameters. Such an approach allows us to evaluate the main contributions of untrapped and trapped particles to the transverse and longitudinal dielectric tensor components for electromagnetic waves in tokamaks, straight mirror-traps, laboratoty dipole magnetospheric plasmas and inner part of the Earth's magnetosphere.

KEY WORDS: Vlasov equation, kinetic wave theory, tokamaks, mirror traps, magnitospheric plasmas.

SUPERBANANA FOKKER-PLANCK EQUATION FOR TOKAMAKS WITH THE STRONG TOROIDAL FIELD RIPPLES

Yu.K. Moskvitina, V.O. Yavorskij, K. Schoepf

Full Text :   (322 kB) 

Abstract
The Fokker-Planck description of collisional ripple transport processes of fast ions is extended for tokamaks with strong toroidal field (TF) ripples. The topology of superbanana orbits generated by the TF ripple drift of banana "guiding" centers is analyzed in terms of the adiabatic invariant. The transport coefficients of a 4D Fokker-Planck equation are derived for the case of strong TF ripples. This study aims at a generalization of the kinetic simulation of fast ions in plasmas of present-day and next generation tokamaks.

KEY WORDS: 3D Fokker-Planck equation, toroidal field ripples, COM space, superbanana orbits, alpha particle losses.

TOPOLOGY OF SUPERBANANA ORBITS IN TOKAMAKS WITH TF RIPPLES

A.O. Moskvitin, V.O. Yavorskij, K. Schoepf

Full Text :   (339 kB) 

Abstract
The topology of banana guiding center orbits of fast ions in tokamaks with toroidal field (TF) ripples is considered. Analytical expressions determining the stagnation orbits and boundaries of regions with the closed orbits in the phase space are derived. Thoroughly studied is the modification of the topology of superbanana orbits due to the variation of the TF ripple magnitude δ. Contour plots of the adiabatic invariant of banana guiding center motion are presented for different values of δ. A comparison of the results of semi-analytical consideration and graphical interpretation of the adiabatic invariant is provided.

KEY WORDS: banana, superbanana, locally trapped particles, toroidal field ripples, adiabatic invariant of motion, tokamak

RADIATION OF THE NONRELATIVISTIC OSCILLATOR IN A PERIODICAL WEAKLY INHOMOGENEOUS MEDIUM

V.I. Tkachenko, I.V. Tkachenko

Full Text :   (310 kB, Rus.) 

Abstract
Radiation of a charged oscillator moving with a nonrelativistic constant speed in a medium with periodical permittivity weakly varying in the space was considered. It was shown that in such environment parametric radiation may be stipulated by the Vavilov-Cherenkov effect as the radiation of a single resonant wave (one-wave radiation) or as radiation of two waves (two-wave radiation) which are parametrically related by the periodic inhomogeneity of medium. The cases of radiation of resting oscillator or charge moving without oscillations are considered. Calculations show that under two-wave resonant radiation its power is proportional to the typical parameter of inhomogeneity. Angles of wave's propagation under one-wave or two-wave radiation may coincide, but the frequency of a two-wave radiation is half as great as the observed one-wave radiation frequency

KEY WORDS: radiation of a charged oscillator, nonrelativistic speed, weakly inhomogeneous medium, оne-wave resonant radiation, two-wave resonant radiation

DETERMINATION OF PORE SIZES TRACK MEMBRANES RECEIVED AT THE IRRADIATION POLYMER BY HEAVY IONS

A.F. Dyachenko

Full Text :   (635 kB, Rus.) 

Abstract
The basic, most widely applied methods for determination of pore sizes track membranes: conductometric method and a bubble method are considered. Their possibilities and application are discussed. Two various variants of compact experimental cells and measuring equipment for determination of pore diameters track membranes by a bubble method are created. Experimental researches on production track membrane samples by an irradiation polymeric polyethylene terephthalate (PET) film with thickness 6 µm accelerated on pre-stripping section of the Kharkov heavy ions linear accelerator Ar¹²⁺ ions with energy near 1 МеV/amu and its subsequent physical and chemical processing for formation set size pores are carried out. This researches have enabled to prepare track membrane samples with pore diameters ³ 0,05 μm for development of bacteriostatic action membranes for water-preparation systems.

KEY WORDS: track membranes, linear accelerator, heavy ions irradiation, polymeric film, pore diameters, bubble method, conductometric method.

THE STRUCTURE OF NANOMETRIC YTTRIUM - IRON GARNET FILMS

V.G. Kirichenko, O.V. Kovalenko, Yu.G. Mashkarov

Full Text :   (475 kB, Rus.) 

Abstract
The results of research of processes of forming of films of yttrium - iron garnet (YIG) by the methods of ion-beam dispersion on of gadolinium- gallium garnet are presented. As a result of an ion-beam besieging from Mossbauer spectroscopy of conversion electrons data the amorphous paramagnetic films were formed. The layer analysis of films by Rutherford back scattering spectrometry result in a conclusion about variable element composition of YIG films. Phase composition is inhomogeneous by the thickness of tapes. There is some diminishing of maintenance of iron as far as setting on to fight of superficial layers of tapes. In addition, on the surface of YIG films gadolinium is diffused.

KEY WORDS: thin films, iron-yttrium garnet, conversion electron Mossbauer spectroscopy, spectrometry of Rutherford backscattering, element and phase composition.

METHODS OF THE SPECTRAL CHARACTERISTIC INVESTIGATION OF THE INTENSIVE X-RAY FROM ELECTRONS IN CRYSTALS

A.M. Azartsov, G.L. Bochek, A.A. Kapliy, S.K. Kiprich, V.I. Kulibaba, A.A. Mazilov, N.I. Maslov, V.D. Ovchinnik, S.M. Potin, G.P. Vasilyev, V.I. Yalovenko

Full Text :   (335 kB, Rus.) 

Abstract
Two methods of the spectral characteristic investigation of the intensive X-ray from electrons in crystals are proposed. The first method is based on the registration of the characteristic X-ray radiation from various targets induced by X-ray from crystal. The second method is based on the measuring of the photon spectra Compton scattering on the target-scatterer.

KEY WORDS: relativistic electron beam, crystal, intensive X-ray radiation, characteristic X-ray radiation, Compton scattering

EVOLUTION OF MAGNETIZATION IN SLIGHTLY DOPED BY SILVER OF TEXTURE YBCO-CRYSTALS

D.A. Lotnyk, R.V. Vovk, A.A. Zavgorodniy, M.A. Obolenskii

Full Text :   (580 kB, Ukr.) 

Abstract
In present work magnetizations M(B)-curves in YBa₂Cu₃O_7-δ and YBa₂Cu_3-xAg_xO_7-δ (х ≈ 0.02) the texture samples are experimentally investigated. There is exists a maximum of magnetization at an intermediate field (''fishtail effect'' (FE) was observed in a wide temperature range 40 K<T<75 K at the magnetic field H||c. It is shown that bulk pinning dominates at low temperatures, while surface barriers dominate at high temperatures. The value jc,max for YBa₂Cu_3-xAg_xO_7-δ crystal shifts to the higher values of magnetic field as compared to the undoped one. This behavior, possibly, the created is related to the presence of additional pinning centers by the silver atoms.

KEY WORDS: HTSC-crystals YBaCuO, peak effect, pinning, creep

INFLUENCE OF RADIATION DAMAGE ON ACCUMULATION AND DISTRIBUTION OF DEUTERIUM IN FERRITIC/MARTENSITIC STEELS

G.D. Tolstolutskaya, I.E. Kopanets, A.A. Makienko, V.V. Ruzhytskiy, S.A. Karpov, A.V. Nikitin

Full Text :   (540 kB, Ukr.) 

Abstract
The influence of preimplanted argon (E_ion=1,4MeV) on deuterium trapping in EP-450 and EI-852 steels was studied using methods of ion implantation and the nuclear reaction D(³He,p)⁴He. Trapping, retention and depth profile evolution of deuterium atoms in steels after implantation or postimplantation annealing in range 300…1500 K were obtained using ³He ions with energy of 0,7 and 1,0 MeV. The implantation of 10 keV deuterium ions up to dose of 1×10¹⁶ см^-2 was done at room temperature of samples. The dependence of trapped deuterium atoms amount on annealing temperature was determined. It was found that retention of deuterium in steels is strongly enhanced by presence of radiation damages created by argon ions irradiation - the hydrogen release out of crystalline lattice temperature interval shifts on 200 K to higher temperature.

KEY WORDS: ion, deuterium, argon, defects, implantation, depth profile, accumulation.

USE OF RARE-EARTH METALS IN CONTACT STRUCTURES

V.A. Tsymbal, I.N. Kolupaev

Full Text :   (1113 kB, Rus.) 

Abstract
Application of films of rare-earth metals (REM) is examined as materials of diffusive barrier. In particular, possibility of stabilizing of the contact systems is studied due to thermodynamic properties of REM as alternative material for silicides. The mechanisms of stabilizing and degradation of both monoelement and compound films of rare-earth metals (ytterbium) in composition of the pin-metallization systems are investigated by the methods of Rutherford back scattering, translucent electronic microscopy and X-ray diffractometry. It is found that from investigated pair only Ti/Yb is able to prevent formation of oxides of Yb on the boundary surface. It allows to use properties of the Ti/Yb contact to control the speed of solid- phase reactions on the border of Yb-GaAs. Use of contact of Yb on GaAs with stable parameters is possible exceptionally through additional layers as diffusive barriers.

KEY WORDS: contact systems degradation, poly-crustal diffusive barriers, recrustallization, diffusive permeability, pin-metallization systems, Rutherford back scattering.

TO THE QUESTION OF USE OF THE STATISTICAL THEORY FOR CALCULATION OF THE PRODUCTION CYCLE

O.M. Pignasty, V.D. Khodusov

Full Text :   (282 kB, Rus.) 

Abstract
In phase technological space the condition of industrial system is certain. The "know-how" is set by a normative technological trajectory. Technological process on each technological operation is presented by technology factors with normative parameters of manufacture and maximum deviations from them. With use of criterion function of technological system expression for calculation of duration of a production cycle of a party of base products is written down. Conditions of synchronization of technological process for continuous production about partitioning the period of a production cycle on phases are received.

KEY WORDS: synergetics, base product, microscopic description, distribution function, engineering-production function, generating function, balances equation, production cycle, the terms of the synchronization process