The effect of ultraviolet radiation on the mass loss kinetics of a sample of model polymer composite material in a vacuum chamber at a pressure of $10^{-5}$ Pa was studied. The source of ultraviolet radiation was a deuterium lamp DDS-30. A mass loss sensor based on quartz microbalance was used to measure the mass loss kinetics. A comparative analysis of the experimental time dependences of mass loss of the model material samples heated to ($70\pm 1$)~\textdegree C and samples when exposed to ultraviolet radiation, whose temperature is also kept equal to ($70\pm 1$)~\textdegree C, was conducted. The results of the analysis showed that simultaneous action on the model material in a vacuum of heat and ultraviolet radiation leads to an increase in the rate of mass loss of the sample, especially in the initial period of exposure --- during the first 10 hours after turning on the radiation source. The latter is explained by the composition of the model material. For qualitative interpretation of the experimental results, mathematical models describing the kinetics of mass loss under both thermal exposure and combined exposure of the sample material to heat and ultraviolet radiation, as well as a model of condensation of gas release products on the sensitive element of the mass loss sensor were proposed.
Show AbstractThe effect of proton irradiation on the process of changes in the surface structure of K-208 glass caused by the formation of microcracks and gas-filled bubbles was studied using atomic force microscopy methods. The K-208 glass plates, which are used to protect solar cells of spacecrafts, were chosen as experimental samples. As a result of the analysis of experimental data obtained by atomic force microscopy, it was found that on the surface of K-208 glass irradiated in vacuum ($10^{-4}$ Pa) by protons with an energy of 20 and 30 keV at a flux density of $\varphi_p =6{,}0 \cdot 10^{10}$ cm$^{-2}$s$^{-1}$ and fluences $\Phi_p = (10^{15} \div 6{,}6\cdot 10^{16})$ cm$^{-2}$ gas-filled bubbles and microcracks are formed, the characteristic sizes of which grow with increasing fluence. It was shown that for the same values of $\varphi_p$ and $\Phi_p$ irradiation of K-208 glass with protons with energy of 20 keV does not lead to the formation of microcracks.
Show AbstractTopical issues of improving the technologies of bone implant sterilization for solving the problems of modern bioimplantology and creating innovative combined methods based on the combined effect of sterilizing factors of various physical and chemical nature are considered. The results of experimental developments of the authors, as well as data from other researchers, are presented, indicating the prospects of combined radiation technologies, the effectiveness of their use in comparison with currently used methods in medical practice. The importance of continuing further complex structural and functional studies of bone tissue for optimizing the parameters of sterilization modes under one-stage ozone and radiation exposure, as well as when using them in combined technologies, is noted. Priority tasks are formulated and methodological approaches to the practical implementation of one of the main conditions of radiation treatment - the maximum permissible, objectively controlled reduction of the dose load on tissues with ensuring their necessary sterility are proposed. Particular attention is paid to the importance of finding alternative (above) methods of sterilization, the use of which will expand the possibilities of single-stage methods and combined radiation technologies.
Show AbstractThe first results on the selection of events of $ep\rightarrow e\pi ^{+}\pi ^{-}p$ exclusive electroproduction from the CLAS12 detector experimental data in the resonance area for the beam energy $E_e = 6.5$GeV are presented in this report. For the $ep\rightarrow e\pi ^{+}\pi ^{-}p$ reaction the missing mass distributions were obtained for four topologies corresponding to different sets of detected particles. The primary selection criteria were worked out and the invariant mass for the various pairs of particles were obtained. The obtained distributions demonstrate the reliability of the algorithms reconstructing the final particles in exclusive electroproduction reactions.
Show AbstractThis article presents an approach for extracting unpolarized transverse, longitudinal, transverse-transverse, longitudinal-transverse structural functions. The extraction of structure functions is performed from experimental data on the differential cross sections of one-pion production obtained with the CLAS detector (Jefferson Laboratory, USA). The available data cover a wide kinematic range for the invariant mass of the final hadronic system W < 1.7 GeV and the virtuality of the photon $Q^2$ < 5.0 $GeV^2$. The extracted $N\pi$ exclusive structure functions play a significant role in the study of the structure of the excited states of the nucleon. In the course of the work, new methods for calculating structure functions were developed. The results obtained by various methods are in good agreement with each other.
Show AbstractUsing the objective physical data reliability criteria it was shown that partial photoneutron reaction cross sections for $^{51}$V obtained at Livermore (USA) and Saclay (France) using the method of neu-tron multiplicity-sorting are not reliable because significant systematic uncertainties. In the frame of experimental-theoretical method the new cross sections of such reactions satisfying reliability criteria were evaluated. The disagreements between evaluated and experimental cross sections were analyzed in detail. It was found that in the case relatively light nucleus 5$^{51}$V the main reason of significant sys-tematic uncertainties of the procedure of identification of neutrons from the reactions $(\gamma, 1n)$, $(\gamma, 1n1p)$ and $(\gamma, 2n)$ used in Livermore is the that the part of the reaction $(\gamma, 1n1p)$ was not taken into account.
Show AbstractThe correlations between the electric dipole polarizability and neutron skin thickness are studied by the doubly magic nuclei~$^{48}$Ca, $^{78}$Ni, $^{132}$Sn, and $^{208}$Pb. The strength distribution of the $E1$~transitions is calculated within the random phase approximation model based on the Skyrme nuclear energy density functional.
Show AbstractIt was found before that experimental $(\gamma, 1n)$, $(\gamma, 2n)$ and $(\gamma, 3n)$ reactions cross sections obtained for many nuclei using the beams of quasimonoenergetic annihilation photons and the method for photoneutron multiplicity sorting do not satisfy to objective physical criteria of data reliability. Using the experimental-theoretical method of evaluation the new data on partial and total photoneutron reaction cross sections satisfying the mentioned criteria were obtained. It was shown that in the majority of cases significant disagreements between evaluated and experimental cross sections are because presence of noticeable systematical uncertainties of the processes of identification of multiplicities of detected neutrons. The new kind uncertainties from the loss of many neutrons from $(\gamma, 1n)$ reaction were found out for several nuclei ($^{75}$As, $^{127}$I, $^{181}$Ta). The evaluation of reliable cross sections $\sigma(\gamma, 1n)$, $\sigma(\gamma, 2n)$, $\sigma(\gamma, 3n)$, $\sigma(\gamma, sn) = \sigma(\gamma, 1n) + \sigma (\gamma, 2n) + \sigma (\gamma, 3n)$ and $\sigma(\gamma, xn) = \sigma(\gamma, 1n) + 2\sigma (\gamma, 2n) + 3\sigma (\gamma, 3n)$ was done for $^{206,207}$Pb. It was shown that for both isotopes $^{206,207}$Pb as well as for $^{208}$Pb investigated before similar to $^{75}$As, $^{127}$I, $^{181}$Ta the competitions between various reactions cross sections testify to unreliability of experimental data.
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