Moscow University Physics Bulletin最新文献

The analysis of a phenomenological model of the baroelectric effect, developed in the works of Professor V.I. Grigoriev, is carried out. This model comprises two sets of equations: those describing the motion of volume elements within a solid, and a phenomenological equation determining the electric charge density induced in conductors under the influence of an inhomogeneous voltage. The latter can be expressed in two forms: one in which the electric charge density generated in electroneutral conductors requires a non-zero surface charge density, and another in which the surface charge density is zero for any pressure distribution along the conductor. In Professor V.I. Grigoriev’s works, a phenomenological model of the baroelectric effect was proposed that necessitates a non-zero electric charge density on the body’s surface. The aim of this study is to investigate the baroelectric effect using a phenomenological equation that does not require surface electric charges.

The paper demonstrates the feasibility of applying the direct energy minimisation method in conjunction with the Peng–Robinson equation of state and the Lohrenz–Bray–Clark model for calculating the density and viscosity of binary hydrocarbon mixtures, as well as mixtures of hydrocarbons with carbon dioxide. The accuracy of the obtained numerical simulation results was assessed by comparing the calculated values of the density and dynamic viscosity of the phases (liquid and gas) with experimental data published in the literature. It is shown that the approach considered in the paper allows, with good accuracy (up to 10(%)), prediction of the densities and viscosities of the phases for binary hydrocarbon mixtures containing components with up to eight carbon atoms.

The issue of water molecule formation in asteroid regolith has been considered. The possibility has been shown for the release of oxygen atoms from the silicon dioxide crystal lattice in the regolith as parts of silver hydroxide molecules. Silver hydroxide, in turn, can relatively easily react with hydrogen, which leads to the formation of water and silver. In this way, the possibility has been demonstrated for the formation of water molecules incorporated into the near-surface soil of an asteroid. The proposed mechanism for the formation of water molecules does not require such an unlikely event as the impact of two solar wind protons at a single point. In the situation considered, it is only necessary that the end of the proton track falls in the region where elements of the quartz lattice and metal sulphides are in contact. The presence of water molecules in the asteroid soil may affect the photoelectric properties of its regolith and the parameters of the dusty plasma system above the asteroid. A way to identify the nature of water formation on an asteroid may be the combination of a method for detecting water on asteroids, based on the observation of dust near the surfaces of these celestial bodies, and a method that uses the detection of neutron fluxes passing through regions of the surface of the celestial body.

This paper is devoted to the development of a generalised formalism of statistical physics. The thermal equation of state for a gas with a two-particle interaction potential is obtained within the framework of Rényi statistics. An auxiliary inverse temperature distribution, which provides the established dependence of the terms in the equation of state on the generalising parameter (q), is introduced and analysed. Based on the results obtained, an expression for the average energy of the system under study in Rényi statistics is derived. Assumptions about the possible nature of the parameter (q) are proposed, and promising directions for further research are outlined.

This study investigates the modification of the surface structure and composition of the nickel-based superalloy Hastelloy C-276 using a 10 keV argon gas cluster ion beam (GCIB). The possibility of either smoothing or nanostructuring the surface relief following preliminary electrochemical polishing is demonstrated. The changes in the surface composition of the alloy under gas cluster irradiation are examined.

We observed a B6.2-class solar flare in active region NOAA 12651 using the HSFA spectrograph at the Ondřejov Observatory in hydrogen spectral lines. After processing the spectra, the integral emission fluxes in the H(alpha), H(beta), and H(varepsilon) lines were determined. Within the heated-gas approach, a theoretical reconstruction of the plasma parameters was performed, taking into account the physical conditions in the chromosphere, including self-absorption in the spectral lines. Treating the observed fluxes requires the assumption of inhomogeneous gas. Agreement between the theoretical and observed fluxes is achieved in a model involving the superposition of two gas layers. Behind lies a dense gas with concentration (N) ranging from (3times 10^{12}) to (3times 10^{13}) cm({}^{-3}), and between it and the observer is a rarefied layer where (N=(3{-}6)times 10^{10}) cm({}^{-3}). The layer thickness is in the range from 600 to 3000 km, the temperature—between 4000 and 7200 K, and the turbulent velocity—from 0 to 90 km/s. The presence of dense regions indicates that the source of the observed emission originates from the middle chromosphere, not higher than 1000 km.

This study is dedicated to the influence of thermal annealing regimes on the magnetic permeability of (CoFe)({}_{75})Si({}_{10})B({}_{15}) amorphous ribbon samples. Due to their unique structure, amorphous materials are distinguished by their high magnetic properties, which can be significantly influenced by thermal annealing processes. In this work, the dependence of maximum magnetic permeability on isothermal holding time and temperature during thermal annealing in air at 200–400({}^{circ})C was investigated, and diffusion processes were also studied. The main objective is to understand how the maximum magnetic permeability of (CoFe)({}_{75})Si({}_{10})B({}_{15}) amorphous ribbon samples changes at different temperatures and isothermal holding times. The results show that annealing at temperatures between 300–400({}^{circ})C significantly improves the magnetic permeability of the ribbons, thereby expanding their potential applications. This study identifies how the magnetic properties of amorphous ribbons can be enhanced through thermal annealing. This research emphasizes the importance of optimizing thermal annealing to further develop the application areas of amorphous ribbon.

An analysis of the requirements for ((gamma,n)) experiments involving fast neutron spectrometry is provided for (gamma)-ray energies in the E1 GR region; the parameters of collimated Compton radiation sources at HI(gamma)S and the National Center for Physics and Mathematics (NCPM); the characteristics of the neutron spectrometer proposed for the NCPM; and the principles of one-dimensional time–coordinate compensation for neutron spectrometer scintillators. Initial experiments have been conducted to investigate the potential for improving the efficiency and resolution of such a spectrometer using the time–coordinate compensation method.

The gravitational interaction of a classical moving charge with an infinite straight cosmic string with linear energy density (mu) is considered. The string generates a gravitational conical background with a small relative angular deficit (beta^{prime}=4Gmu). The geodesic of the charge lies in a plane transverse to the string. The scattering is described by the Lorentz factor (gamma) and the impact parameter (b). In the leading order in (gamma), the gravitational perturbation of the charge and the string is computed within the perturbation theory. In the second perturbation order, the total energy radiated in the form of electromagnetic waves is calculated, as well as the spectral–angular and polarization characteristics of the bremsstrahlung. The radiation is characterized by a concentration in a cone with opening angle of the order of (1/gamma), with the dominant contribution to the emission coming from frequencies of the order of (gamma/b).

The formation of superconducting pair correlations between like nucleons in the ground state of spherical even–even nuclei is considered within a special Bogoliubov transformation. The influence of the monopole pairing interaction on the energy of single-particle states is taken into account. It is shown that the appearance of pair correlations depends on the particle number and shell structure. In open subshell nuclei the correlations exist for arbitrarily weak attractive monopole interaction and nucleon pairs are distributed over all subshells involved in the pairing interaction. It is confirmed that the superconducting pair correlations arise if the coupling constant exceeds a certain threshold value. Rough upper and lower estimates are obtained for the threshold value.