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Agenda:
1. Defense of the the Ph.D. thesis by Eremenko M.V. (Skoltech) "Atomic local order on the nanometer scale in ferroelectric relaxors".
2. Defense of the Ph.D. thesis by Matveev V.A. (PNPI NRC KI). “Study of promising Ti/TiO2 bilayer structures in polarizing neutron optics”
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"The system of experimental and theoretical methods for studying physical and chemical properties and processes of medieval fresco painting"
O. Philippova, A. Dmitriev
The Group of Neutron Activation Analysis FLNP carries out complex research of fresco paintings from the UNESCO World Heritage List architectural monuments. Unique pre-Mongolian 12th century frescoes from St. George Cathedral of Yuryev Monastery (Veliky Novgorod) and Christ’s Transfiguration Cathedral of Mirozhsky Monastery (Pskov), as well as 16th century frescoes from Smolensk Cathedral of Novodevichy Convent (Moscow) were studied. Works are performed in collaboration with organizations from the Ministry of Culture of the Russian Federation – State Institute for Art Studies and Interregional Agency for Scientific Restoration of Works of Art.
For in situ elemental composition determination X-ray fluorescence analysis is used. In laboratory – for the first time in Russia – classical neutron activation and prompt gamma activation analysis were used. Molecular and mineral composition is analyzed using infrared spectroscopy. Stratigraphy and chemical microanalysis are additional methods. The sets of pigments used for painting, the presence/absence and compositions of organic binders, as well as the compositions of plaster bases have been determined. The data obtained are of significant interest to domain experts: restorers (for planning and carrying out restoration and conservation works) and art historians (for solving a wide range of problems, first of all, attribution, determination of painting technique, digital reconstruction of fresco painting fragments).
12th century fresco of St. George from St. George Cathedral of Yuryev Monastery: view at the present time (left) and the possible original coloration (right)
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"The most probable nuclear level densities and radiative strength functions from the analysis of the two-step cascade gamma-decay"
Sukhovoj A.M., Mitsyna L.V.
The most probable nuclear-physical parameters (the radiative strength functions and nuclear level density) obtained analyzing the reaction of radiative capture of thermal neutron by a nucleus were collected for 43 nuclei from the 40≤ A≤200 mass region. The empirical method, which is created and developed in Dubna, allows a simultaneous determination of these strong-correlated nuclear-physical parameters from the experimental intensities of the cascades of two sequential γ-transitions between the compound-state (neutron resonance) and a group of low-lying levels of an excited nucleus. The energy dependences of the radiative strength functions and nuclear level density were calculated with the fitted parameters obtained from the best fittings of the model-described intensities of primary transitions of the two-step cascades to the experimental spectra. In the spectra fittings the system of non-linear equations, which connect the experimental intensities with the fitted parameters of the models for both required radiative strength functions and nuclear level density, is Monte-Carlo solved using four pairs of tested models of their energy dependences. The nuclear-physical parameters, which have been extracted simultaneously from indirect experiment, enable to acquire unique information about dynamics of interaction of boson- and fermion-states of nuclear matter. In the paper the results of the empirical analysis for all investigated nuclei are presented.
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"Modification of structural, chemical and optical properties of TiO2/SiO2 structures after ion irradiation"
Tran Van Phuc
(based on the materials of phd thesis’s)
The author will present the results of investigation the influence of ion irradiation on structural, chemical, and optical properties of TiO2/SiO2 system, which formed the basis of his dissertation work. The work is devoted to the study of processes that cause degradation of semiconductor solar cells during operation. Using noble gases ion irradiation at different energies the author has established, that the cascade mixing process is responsible for the extension of the transition layer between TiO2 and SiO2 contact materials that occurs dominantly toward the substrate. It was found that the mixing is not proportional to the damage amount, whereas the ion energy transfers to the target atoms create deeper damage plays a crucial role in broadening the TiO2/SiO2 mixed area. It was found that the concentration of TiO2 increase after irradiation, which leads to the growth of deposited energy level in transition layers, is reflected in the enhancement of mixing amount. The nonlinear extreme behavior of the optical properties of the TiO2/SiO2 contact after irradiation has been established. In particular, it was shown that the refractive index and the extinction coefficient of TiO2/SiO2 contact increase at the energy of implanted ions below 250 keV and decrease at the energy of implanted ions higher than 250 keV.
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"Space nuclear physical instruments for studies of planets and near-Earth space"
Mokrousov Maxim Igorevich (Space Research Institute, Moscow)
(based on dissertation for degree of Doctor of science)
The author shall present descriptions of innovated nuclear instruments, which have been created under his leadership for studies of neutron radiation of upper atmosphere of the Earth, for studies of neutron radiation of the Mars from interplanetary NASA's spacecraft Mars Odyssey and ESA's spacecraft TGO, for studies of neutron radiation of the Moon from NASA's lunar spacecraft LRO and for studies of neutron and gamma-ray radiation of Mercury from ESA's interplanetary spacecraft BepiColombo.
"Estimation of water mass fraction in the subsurface substance of Mars based on measurements of neutron albedo of its surface"
Nikiforov Sergey Yurievich Space Research Institute, Moscow
(based on dissertation for degree of Candidate of science)
The author shall present results of data analysis, which were measured by the instrument DAN onboard the NASA's Mars rover Curiosity for characterisation of the neutron albedo of the Martian surface. The concept shall also be presented of the perspective instrument ADRON-RM for the similar experiment onboard the ESA's Mars rover ExoMars, for which the author is the leading physicist-experimentator.