P15-2016-1 (14221.520)
Didyk A. Yu., Gulbekyan G. G., Myshinskiy G. V.
Anomalies on the Inner Surfaces of the Xenon High-Pressure Chamber
XeHPC 250 Bar with the Synthesis of Microparticles of Complex Composition
under Irradiation with Bremsstrahlung Threshold
Energy of 10 MeV
Natural xenon at an initial pressure of 250 bar in a special chamber (XeHPC)
was irradiated for 60 h 16 min (2.17· 105 s) by braking γ-rays with
a threshold energy of 10 MeV at the electron accelerator MT-25 at an average
intensity of the beam of 20–22 µA. With increase in temperature the
pressure in the steady
state at the beginning of exposure grew up to 270 bar. After opening of the XeHPC both internal chambers
with all the structures and particles, but without gas, were measured using
a γ-germanium detector.
Visual inspection of the inner chambers showed visible dense greenish-yellow
coating of
significant thickness formed on their
surfaces.
X-ray microprobe analysis (RMPA) and SEM studies allowed us to determine the composition of the synthesized particles.
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P11-2016-4 (255.5)
Amirkhanov I.V. et al.
Investigation of Quasi-Stationary States in the Double-Barrier Open Well
In this paper an investigation of solutions of quasi-stationary states in
the framework of the Schroedinger equation with complex energies with
piecewise constant potentials for various values of the parameters of the
potential is conducted. Quasi-levels are found for the under- and
above-barrier cases. For the given potential barrier heights the number of
under-barrier quasi-levels for the double-barrier potential is more than for
the single-barrier potential. The calculations show that the real part of
the energy varies smoothly and the imaginary part of the energy changes
irregularly when changing the parameters of the potential.
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p9-2016-6 (927.7)
Nozdrin M.A. et al.
Diagnostics at JINR LHEP Photogun Bench
The photoinjector electron beam quality dramatically depends on the laser driver beam quality. For laser beam diagnostics a "virtual cathode"
system was realized at the JINR LHEP photogun bench. The system allows one to image laser beam profile at the cathode. The AVINE software complex developed in
DESY Zeuthen is being used for imaging. Equipment for emittance measurement using the slit method was installed. The original emittance calculation software
EmCa was created and tested with the laser beam.
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E17-2016-8 (116.0)
Bogolubov N.N. (Jr.), Soldatov A.V.
Variational Master Equation Approach to Dynamics of Magnetic Moments
Non-equilibrium properties of a model system comprised of a
subsystem of magnetic moments strongly coupled to a selected Bose
field mode and weakly coupled to a heat bath made of a plurality
of Bose field modes were studied on the basis of non-equilibrium
master equation approach combined with the approximating
Hamiltonian method. A variational master equation derived within
this approach is tractable numerically and can be readily used to
derive a set of ordinary differential equations for various
relevant physical variables belonging to the subsystem of magnetic
moments. Upon further analysis of the thus obtained variational
master equation, an influence of the macroscopic filling of the
selected Bose field mode at low enough temperatures on the
relaxation dynamics of magnetic moments was revealed.
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P13-2016-10 (405.9)
Pepelyshev Yu.N., Tsogtsaikhan Ts.
Prediction of the Thermal Dynamic Parameters Fluctuation of Coolant System of the IBR-2M Reactor Using Neural Networks
This paper presents an artificial neural network method for long-term
prediction of the thermal dynamic parameters of primary coolant circuit of
the IBR-2M reactor. The main goal is to predict the temperature and liquid
sodium flow rate through the core and thermal power. It is shown that the
prediction can reduce three times the effects of slow reactivity
fluctuations in power and decrease the requirements for the automatic power
stabilization system. Nonlinear autoregressive neural network (NAR) with
local feedback connection has been considered. The results of prediction
error ~ 5% coincide with the experimental ones.
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P11-2016-14 (1.859.0)
Batgerel B., Nikonov E.G., Puzynin I.V.
A Procedure for Constructing Symplectic Numerical Schemes for Solving Hamiltonian Systems of Equations
A new procedure for constructing symplectic numerical schemes for solving the Hamiltonian systems of equations is proposed.
A method for symmetrization of the obtained symplectic numerical schemes is suggested. The numerical schemes constructed by the above procedure conserve the energy
of a system on the large interval of numerical integration for relatively large integration step in comparison with the Verlet method which is usually used for
solving equations of motion in molecular dynamics. Results of numerical experiments are given. These results show the main advantages of the obtained symmetric
symplectic numerical schemes of the third order of accuracy for the integration step for the Hamiltonian systems of equations in comparison with numerical schemes
of the Verlet method of the second order of accuracy.
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P13-2016-17 (156.5)
Pepelyshev Yu.N., Popov �.�., Sumkhuu D.
Estimation of Power Feedback Parameters of the IBR-2M Reactor by Square Wave Reactivity
Parameters of the IBR-2M reactor power feedback (PFB) are estimated based on
the analysis of power transients caused by deliberate square wave reactivity
when the pulsed reactor operates in the self-regulation mode.
The PFB of the IBR-2M is described by three linear first-order differential
equations.
Two components of the PFB are responsible for the negative feedback and one,
for the positive. The overall feedback is negative, i.e., it has a
stabilizing effect for the operation of the reactor.
The slowest negative component of the PFB is probably caused by heating of
the fuel.
Periodically repeated in the process of exploitation, estimation of the PFB
parameters is one of the methods to ensure safety operation of the reactor.
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P13-2016-20 (1.004.3)
Pepelyshev Yu.N. et al.
Application of the Properties of Toeplitz Matrices of the Noise Correlation Characteristics to the Diagnostics of the IBR-2M Pulsed Reactor
The safeguarding of a nuclear reactor during the operation process is one of
the most significant tasks. The difficulty is in the necessity to use
nondestructive methods. One of such perspective methods is the neutron noise
diagnostics of a nuclear reactor.
Possibility of the noise diagnostics by the new method of norms of positive
definite Toeplitz correlation matrices is studied. The advantage of this
method is its purely mathematical nature; no model of the process is
employed.
The neutron noise analysis of the IBR-2M pulse energy has been carried out
by the represented method. Both the static state and dynamic
state of the reactor have been studied.
Frequency analysis of unstable components of the reactor noise has been
carried out. The main unstable components of the neutron noise are
frequencies of 0.8 and 1.6 Hz, which are conditional on the vibration of the
movable reflector blades of the reactivity modulator. The results of this
diagnostics have been compared with the results of the classical spectral
analysis.
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E7-2016-21 (292.6)
Volkov V.V., Cherepanov E.A., Kalandarov Sh.A.
Interpretation of the Mechanism of Spontaneous Fission of Heavy Nuclei in the Framework of Dinuclear System Conception
A new approach to the interpretation of the process of spontaneous fission
of heavy nuclei is suggested. It is based on nuclear physics data which are
obtained in heavy ion collisions. The process of spontaneous fission
consists of three sequential stages: clusterization of the valent nucleons
of a heavy nucleus into a light nucleus-cluster, which leads to the
formation of a dinuclear system; evolution of the dinuclear system which
proceeds by nucleon transfer from the heavy to light nucleus; and decay of
the dinuclear system from the equilibrium configuration into two fragments.
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P13-2016-23 (543.803)
Tsulaia M. I. et al.
Upgraded Experimental Setup KOLHIDA Designed to Study Interactions of Polarized Neutrons with Polarized Nuclei
We study the adsorption of anionic surfactant, sodium dodecyl diphenyloxide disulfonate (SDDD) on three types of polyethylene terephthalate (PET)
substrates from aqueous solutions of SDDD of different concentrations. Neutral electrolyte (KCl) was added to the solutions to vary the ionic strength.
Three types of substrates were used: 1) original PET film; 2) etched nonporous film, obtained from pristine film by chemical etching and bearing negative charge
on the surface; 3) etched porous membranes, fabricated from pristine film by ion irradiation and subsequent chemical etching.
The membranes have negative charge on the flat surface and on the inner pore walls.
The comparison shows that the negative charge on the flat surface has weak effect on adsorption of the anionic surfactant,
and the SDDD adsorption on the inner walls of pores is much weaker than on flat surface, even if the pore radius is significantly larger than the
Debye length. This “exclusion” effect strongly depends on ionic strength of solution.
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E14-2016-24 (664.7)
Nyamdavaa E. et al.
Preparation and Characterization of La1-xCexCoO3 Perovskite Oxides for Energy Materials
Cerium-doped lanthanum cobaltite perovskites (La1-xCexCoO3
with x = 0, 0.2, 0.4) were prepared by the sol-gel method (calcined for 5 h at
750ºC) and characterized by X-ray diffraction (XRD), X-ray absorption
(XAS), energy-dispersive X-ray spectroscopy (EDS), and BET surface area
analysis. The results showed that the cerium doping promoted the structural
transformation of LaCoO3 from rhombohedral into the cubic structure.
High specific surface area and small crystallite size are achieved at x = 0.2.
The XAS results confirmed the formation of compound La1-xCexCoO3.
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P14-2016-26 (691.931)
Artoshina O. V. et al.
Structure and Phase Composition of the Titanium Dioxide Thin Films
Deposited on the Surface of the Metallized Track Membranes from
Polyethyleneterephthalate by Reactive Magnetron Sputtering
Thin films of TiO2, Ag, Ag-TiO2, Cu-TiO2 deposited on the
surface of polyethyleneterephthalate track membranes (TM) were investigated.
Metals and oxide deposition was carried out by the method of vacuum reactive
sputtering with application of a planar magnetron. The microstructure of
samples was studied by the scanning and transmission electron microscopy
(TEM) techniques. The elemental composition of coatings was investigated
using energy-dispersive spectroscopy. For the identification of phase
structure, X-ray diffraction phase analysis was used at various
temperatures, and the XRD crystal structure patterns of the samples were
obtained by the selected area electron diffraction (SAED) in TEM analysis.
It was found that titanium dioxide on the TM surface can be present in three forms: nanocrystals of tetragonal anatase with impurity
of rhombic brookite and the so-called X-ray amorphous TiO2. Cubical Cu2O was identified in TM metallized by copper.
Optical properties of composite
membranes and films were investigated by the method of absorption
spectroscopy. Calculation of energies of the direct and indirect allowed
optical transitions was carried out based on the analysis of absorption
spectra of the studied composite membranes.
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P6-2016-29 (231.164)
Gustova M. V., Maslov O. D., Sabelnikov A. V.
Application of TEVA Resin for the Separation of the Products of
Photonuclear Reaction 237Np(γ, n) 236mNp → (β–)236Pu
The paper reports on the possibility of using TEVA resin (TRISKEM company),
made on the basis of the Aliquat-336 extractant (a quaternary ammonium
salt), for the isolation and concentration of 236Pu. The 236Pu
isotope was produced as a result of the photonuclear reaction
237Np(γ, n) 236mNp → (β–)236Pu using the linebreak
MT-25 microtron at FLNR, JINR. Plutonium-236 was separated on the TEVA
resin from 237Np target. Products of (γ, f) photonuclear reactions,
daughter products of 236Pu and 237Np, fragments of 237Np(γ, n) (237Np, 232U,
228Th, 233Pa, 137Cs, etc.) induced fission were also separated. The content of the
actinide elements in 236Pu was less than 10-6 Bq/Bq.
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P13-2016-33 (500.863)
Azorskii N. I. et al.
New Type of Drift Tubes for Gas-Discharge Detectors Operating in Vacuum: Production Technology and Quality Control
A device for fabricating thin-wall (straw) drift tubes
using polyethylene terephthalate film 36 µm thick by ultrasonic welding is described together with the technique for controlling their quality.
The joint width amounts to 0.4–1.0 mm. The joint breaking strength is 31.9 kg/mm2
The argon leakage from a tube of volume 188.6 cm3 under a pressure gradient of 1.0 atm does not exceed 0.3 · 10-3cm3min,
which is mainly related to the absence of metallization in the joint vicinity.
The high strength, the low tensile creep due to the absence of glued layers,
and the small value of gas leakage make the new tubes capable of reliable and long-term operation in vacuum,
which is confirmed by the operation of 7168 straw tubes for two years in the NA62 experiment.
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P13-2016-37 (653.4)
Babkin V. A. et al.
Setup for Testing of Detectors at the Nuclotron “MPD Test Beam”
A new specialized setup “MPD test beam” was created at the extracted beam
of the Nuclotron to carry out methodical research and testing detectors for
the MPD experiment at the NICA collider. The setup is described in detail.
Results of the test of fast detectors for the MPD TOF system are presented
as an example of the setup operation.
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P3-2016-39 (514.3)
Êiselev Ì. À., Zemlyanaya Å. V.
Dehydration of the Intermembrane Space in the Multilamellar Membranes of Dipalmitoylphosphatidylcholine under the Influence of Dimethyl
Sulfoxide. Neutron and Synchrotron Study
On the basis of the separated form factors method (SFF), the analysis of
data on the small-angle neutron scattering (SANS) on polydispersed
population of unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC)
in heavy water with dimethyl sulfoxide (DMSO) is carried out. It is shown
that the growth of DMSO molar fraction in water from 0 to 15% leads to
increase of thickness of the bilayer to values of the repeat distance of
multilamellar membranes of DPPC, which means a dehydration of the
intermembrane space and steric contact of the neighbor bilayers of DPPC at a
DMSO molar fraction of 15%.
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E3-2016-43 (1.532.519)
Vu D. C. et al.
Representation of the Radiative Strength Functions in the Practical
Model of Cascade Gamma Decay
The developed in Dubna practical model of the cascade gamma decay of
neutron resonance allows one, from the fitted intensities of the two-step
cascades, to obtain parameters both of level density and of partial widths of
emission of nuclear reaction products. In the presented variant of the model a part
of phenomenological representations is minimized. Analysis of new results
confirms the previous finding that dynamics of interaction between Fermi- and
Bose-nuclear states depends on the form of the nucleus. It also follows from the
ratios of densities of vibrational and quasi-particle levels that this
interaction exists at least up to the binding neutron energy and probably differs
for nuclei with varied parities of nucleons.
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E3-2016-43 (1.532.519)
Omelyanenko M. M. et al.
Low-Noise Pulse-Mode Current Power Supply for Magnetic Field Measurements of Magnets for Accelerators
The described pulse-mode current power supply has been designed and fabricated for the magnetic field
measurement system of superconducting magnets for accelerators. The power supply is based on a current regulator with pass transistor bank
in linear mode. The output current pulses (0—100 A) are produced by using the energy of preliminary charged capacitor bank (5—40 V),
which is charged additionally after each pulse. There is no AC-line frequency and harmonics ripple in the output current,
the relative noise level is less than —100 dB (or 10-5 of RMS value (it is defined as the ratio of output RMS noise current
to the maximal output current 100 A within the operating bandwidth, expressed in dB).
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P15-2016-44 (219.4)
Kabdrakhimova G. D. et al.
Investigation of the Total Cross Sections in the Interactions
of 6He and 4He Nuclei with Si Nuclei at 5—50 MeV/A
The analysis of the experimental excitation functions of the total cross sections of nuclear reactions 6He+Si
and 4He+Si in the energy range 5—50 MeV/A and a brief overview of the techniques by which experimental data were
obtained have been presented. Detailed attention is given to the description of experiments conducted with beams of radioactive
nuclei of the accelerators of FLNR JINR. Analysis of experimental data was performed using the semi-microscopic optical model.
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P4-2016-50 (251.6)
Pupyshev V. V.
The Amplitude Functions Method in the Theory of Two-Dimensional Scattering
In the present work, we formulate and give the mathematical foundation of the amplitude functions method. This method is adopted
for solving the radial problem of two-dimensional scattering of a quantum particle by the sum of the Coulomb potential and a central
short- or long-range potential.
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