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The problem considered in this work relates to the physics of liquids. Rather, to the physics of dynamic processes in liquids. The method of quasielastic scattering of slow neutrons was used to study the dynamics of molecules of the water-ethanol system as a function of concentration at a temperature of 8 °C and as a function of temperature at a concentration of X = 0.04 molar particles (mol. particl.). The overall coefficient of self-diffusion of molecules D, its single-particle Ds-p and collective Dcoll components, as well as the time of settled life of a molecule in a vibrational state τ, are determined. The region of small concentrations was studied in detail, where in the vicinity of concentrations X = 0.04 mol. particl. and X = 0.2 mol. particl. two minima are found in the coefficients D and Ds-p. Time τ at these concentrations increases significantly. This indicates a significant decrease in the intensity of the activation mechanism of molecular diffusion at these concentrations, which is quite possibly caused by the binding of water and ethanol molecules into complexes (clusters). Similarly, a deep minimum was found in the D and Ds-p coefficients near the temperature of 4 °С. Time τ at this temperature also increases. That is, at a temperature of 4 °C, the intensity of the activation mechanism of the diffusion of solution molecules decreases. Therefore, at a concentration of X = 0.04 mol. particl. and at a temperature of 4 °C, a special point exists in the water-ethanol system. However, its position does not coincide with the data on scattering light. [ABSTRACT FROM AUTHOR]

The results of studying the dynamics of molecules of solutions of fullerene C60 in benzene and toluene are presented. The studies were carried out by the method of quasi-elastic scattering of slow neutrons. The following were determined: the total self-diffusion coefficient D, its collective Dcoll and single-particle Ds-p contributions, and molecule relaxation time ꚍ0 before and after the dissolution of fullerene. It is necessary to pay attention to the fact that in our case a kind of neutron contrast experiment takes place. The significant difference (more than ten times) in the cross-sections for an incoherent scattering of neutrons by hydrogen and carbon nuclei made it possible to obtain diffusion parameters that characterize the dynamics of solvent molecules exclusively. It turned out that the intensity of diffusion movements of solvent molecules is almost ten times higher than the mobility of fullerene molecules. [ABSTRACT FROM AUTHOR]

The dynamics of atoms and molecules in gel electrolyte based on polyvinyl chloride and a solution of LiClO4 in propylene carbonate was studied by the method of quasielastic scattering of slow neutrons. The coefficients of selfdiffusion of atoms and molecules are determined and a possible variant of the mechanism of charge transport in this system is proposed. [ABSTRACT FROM AUTHOR]

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Neutrons interaction with matter under high density interactions (DI) was considered. It was shown that under neutron cross section measurement with high DI and production as result of interaction neutrons with matter of the second states with great value of such parameters as neutrons cross section, yield and life time probability of the interaction neutron with matter depends on DI and considered parameters. The expressions, related neutrons transmission, cross section and change of the neutrons transmission through the samples pair from different matters, which simultaneously placed on neutron beam, under the change of neutrons transmission sequence through them (transmission asymmetry) with DI and considered parameters of the second states were obtained. Method for revelation for the cross section change under DI change and improved experimental installation were described. [ABSTRACT FROM AUTHOR]

Research of neutron interactions with the matter under density interactions (DI) up to ∼109 cm-2 . s-1, were provided with aim of revelation of possible dependence neutron cross section from DI. The method of research [1] for revelation of such dependence was improved [2]. It consists on transmission asymmetry (TA) of neutrons measurement through of samples pair from different matters. TA was revealed for all pairs containing 235U, in particularly, for pair (235U - Cd) TA consists of (2,541 ± 0,294) . 10-4 that does not contradict to assumption of the cross section dependence from DI. It was defined that correlation related with fission of 235U, and corresponding of relative change of the effective neutron cross section equals ∼2,6 . 10-4. Analysis shows that observed dependence may be treated as the result of secondary states composition of 235U with anomaly great values of neutron cross section, yield, reduced of possibility radioactive transition and small energy, excited by fragment fission. [ABSTRACT FROM AUTHOR]

The problem of handling nuclear power plant irradiated structural materials holds one of the central places in the nuclear power industry. High toxic 10 Be with a half-life of T 1/2  = 1.6 × 10 6 years is discovered in NPP structural materials after reactor operating. 10 Be decays through only electrons' emission. Pure beta emitters are extremely difficult to determine in irradiated structural materials and radioactive waste. We proposed a photoactivation approach for determining the 10 Be activity in NPP samples. The proposed method involves determining 9 Be and 10 B concentrations and subsequent recalculation of 10 Be activity formed in 9 Be(n, γ) 10 Be and 10 B(n, p) 10 Be reactions. The amount of 9 Be and 10 B is determined by samples' photoactivation using an electron accelerator and 9 Be(γ, 2n) 7 Be-, 10 B(γ, p2n) 7 Be-reactions. These reactions' experimental yields were measured for 20, 40, and 55 MeV boundary energies of the bremsstrahlung beam. The proposed technique was tested on samples of ChNPP 2 nd unit irradiated structural materials. The technique's calculated error is about 15-20%; the sensitivity is 1 Bq × g -1 ., (Copyright © 2020. Published by Elsevier Ltd.)