[en] The purposes of the study were: investigation of quasi-elastic scattering (QES) of slow neutrons by water throughout the temperature range of its liquid phase existence; obtaining the data on temperature dependence of self-diffusion process in water; interpretation of the obtained physical data on the basis of the present conceptions of structural-dynamic features of water. A neutron source is the IBR-30 reactor of 15 kW average power having 5 Hz power pulse-repetition rate. Initial neutron energy amounts to 8 and 25 MeV. A pair pulse neutron spectrometer of 0.58 and 2.4 MeV resolution with respect to the initial energy was used to measure neutron spectrum. Measurements were carried out at 300, 400, 500, 548, 600 and 623 K temperatures. The specimen represents a cylinder of 160 mm height and 120 mm diameter consisting of capillary tubes filled with water. The specimen contains approximately 6 g water. Experimental data processing includes obtaining the shape of natural line of QES law and its half-width as a function of scattering angle and temperature containing the data on the self-diffusion process in the liquid under investigation. Integral intensity of QES permits to estimate a mean square of molecule oscillation amplitude. The analysis of the shape of natural line of QES law permits to draw the conclusion, that within 300-600 K range the line has a shape close to Lorentzian It proves that the effect of rotational component of self-diffusion is negligible. The presence of angular dependence of integral intensity of the QES law testifies to the elements of quasi-crystallinity in the microdynamic behaviour of water. Forces of intermolecular interaction in 300-600 K range change slightly. The contrubution of vibrational component to the total coefficient of self-diffusion does not exceed 5-7 %

[en] The experimental data on quasi-elastic scattering (QES) of electrons in water in the range of temperatures from 300 to 600 K are analysed in the framework of models developed for description of the selfdiffusion in the water. An analysis of the shape and dispersion of the QES spectrum enabled to obtain an information on the nature of the selfdiffusion in the water and to determine a number of characteristics of the microdynamical behaviour of water molecules. A contribution of the rotational component into the diffusional motion of water molecules is found to be insignificant. It is established that neither the hoping diffusion model nor the continuous diffusion model enable one to describe satisfactorily the experimentally observed half-widths of the natural lines of QES. Such a description can be achieved in the framework of models incorporating the complex character of the translational diffusion in the water. The temperature dependence of the following parameters of the model were determined: the molecules settled lifetime tau₀(T); the continuous diffusion coefficient D₀(T); the mean diffusion discontinuities. The activation energy of the hoping process was determined from an analysis of the temperature dependence of D₀(T) in the framework of the Frenkel theory. It is concluded that, in the temperature range of 300-600 K, there are no significant changes in the intramolecular forces. The visco-elastic properties of the water are discussed in the framework of the Fisher theory using the temperature dependence of D₀(T). The displacement stress relaxation time tausub(m) is found to be much smaller than tau₀. An approximate equality of molecUlar transport via hoping and continuous mechanisms is an evidence for strong fluctuational deformations of the ice-like quasi-frame even at T approximately 300 K, which result in the significant contribution of the continuous mechanism of the selfdiffusion

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[en] The main problems concerning the choice of a cold moderator for the DIN-1PU neutron spectrometer in the neutron beam No.2 of the IBR-2 reactor are considered. It is concluded, that the cold water grooved moderator is the most suitable one under neutron beam No.2 and spectrometer DIN-2PI conditions. 35 refs.; 12 figs.; 1 tab

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[en] Results of neutron-scattering experiments on ethylene glycol (H-O-CH₂-CH₂-O-H) at T=300, 348 and 393 K are presented. Quasielastic scattering is investigated using the simplest models of the reorientation and diffusion motions. Two reorientation components are observed: the 'fast' component with the radius of rotation R₀≤1.1 A, which is probably connected with the rotation motions of protons of C-H groups and the 'slow' reorientation of the whole molecule with R₀∼1.6 A. Parameters of the translation diffusion motion were obtained using a random jump diffusion model

[en] From the experimental scattering law (SL) of slow neutrons with water being in post-critical state (t=400 deg C) separated is its translational part (SLTP) that is analysed on the basis of two-phase model and is used to extract information on triple correlations in water and to compare with forecasts of generalized kinetic theory. A possibility is shown to describe the slow neutron scattering cross section with subcritical water of the two-phase model; relative concentrations of liquid and gas phases found proceeding from this description agree satisfactorily with those obtained before. Isothermal pressure derivative from SLTP is obtained. A comparison of natural experimental semiwidth of SLTP with forecasts of generalized kinetic theory has shown that even at post-critical temperatures and moderated densities translational motion of water steam molecules can not be described by the solid sphere model, but demonstrates effects connected with the influence of intermolecular attraction forces

[en] The Bayes approach efficiency is analyzed while determining the natural line shape in the spectra of slow neutrons quasielastically scattered from water. The effect od apriori information on the solution character and nature is considered. The natural line shape is reconstructed for three cases of the effect of the resolution function on the experimental curve: strong - ΔEsub(resol),/ΔEsub(exp) = 0.67, moderate - (0.41), and weak - (0.11). The Lorentz and experimental curves are compared. In a different approach parameters of the corresponding lorentzian are detrmined. The both approaches yield practically coinciding curves, and it is concluded that the natural line shape for the case is rather reminiscent to the lorentzian. The Bayes method demostrates adequate stability to variations of apriori information

[en] The data on the frequency spectrum of liquid potassium, obtained from the inelastic neutron scattering experiment in the temperature range 340 K - 550 K, are used to calculate the isochoric heat capacity of this metal to estimate the influence of the anharmonic effects on it and on the interatomic force field of liquid potassium. 5 figs