The problem of generation and propagation of a difference-frequency wave formed as the interaction of two high-intensity high-frequency pump waves is considered and described by the nonlinear Burgers equation. It is known that the evaluation of the nonlinear operator in this equation is particularly difficult due to the necessity of retaining several thousands of spectral components, especially under conditions of shock front formation in the waveform. For this reason, the method which enables to reduce the number of spectral components in the numerical algorithm is considered. The only restriction is that it should not affect the accuracy of calculation of a difference-frequency wave. The above method is compared to an earlier proposed one for a set of harmonics retaining in the nonlinear numerical scheme. It is shown that the new method is more accurate at shorter distances, but it outmatches the previous one on large distances only when using a bigger number of spectral components retained in the algorithm. Such behaviour is explained by the retention of a smaller number of high-frequency and a larger number of combination components.
Show AbstractThe results of previous papers of interplanetary scintillation observation at the modernized meridian-type radio telescope BSA LPI are briefly described. Observation results for the coronal mass ejection (CME) and associated magnetic storm in November 2021 are presented. Scintillation enhancement started at a heliocentric distance of 0.7 AU 27.5 hours after the flare, the geomagnetic storm started 14.5 hours after the start of scintillation enhancement. The possibility of short-time space weather forecast by interplanetary scintillation monitoring data is demonstrated by the analysis results for this event.
Show AbstractGiant galaxies of low surface brightness (gLSB) are difficult to detect due to the presence of a faint extended periphery, which is barely visible against the sky. At the same time, the study of such galaxies is necessary to clarify the mechanisms of formation and evolution of giant disk galaxies. To increase the number of known low surface brightness giant galaxies, it is planned to use machine learning models to solve the binary classification problem. To reduce the dimension of the problem, it is proposed to use as training data the radial brightness profiles of galaxies obtained by processing photometric fits images of galaxies in the HSC2 survey. For this purpose, a system for in-line processing of galaxy images was developed and an isophot analysis of 26008 galaxies in the visually inspected early quadrant of the sky, including 27 gLSB and 13 giant disk galaxies, was carried out. All obtained intensity profiles were visualized on one graph, as a result of which a criterion for selecting galaxies was formulated: for potentially interesting objects, the signal-to-noise ratio at a distance of 30 kpc from the center must be at least 2 in the g and r filters in order for the extended periphery to be clearly detected against the sky.
Show AbstractRadiative cooling of a shocked gas is evaluated for the case of a cold atmosphere of o Cet variable star type. Theoretical fluxes in Balmer and Paschen series of hydrogen and in HeI lines HeIλ4471 and HeIλ10830 are calculated. The difference between atom-ion and electron temperatures behind the shock front is taken into account. The most important elementary processes are included into consideration, such as non-stationary occupation of discrete and continuous hydrogen and helium levels by electron impact and radiative processes in blackbody field of the stellar radiation. The line scattering is calculated in the Biberman-Holstein-Sobolev model. The theoretical Balmer decrement is sensitive to undisturbed gas density. The HeI lines is more than one order of magnitude lower than that of Paschen series and Hγ at low initial shock velocity (50 km/s) and gas concentration of 10^{12} ÷ 10^{13} cm−3. At higher values of shock wave velocity (70 km/s) HeIλ10830 becomes comparable with ones of Paschen lines.
Show AbstractIn 1978, the Sintez experimental telescope was put into operation at the Crimean Astrophysical Observatory (CrAO). The purpose of its creation was to develop technologies for segmented optics, as well as a system for controlling the spatial position of mirrors, including those with the ability to compensate for turbulence in the earth's atmosphere due to the rapid movement of each mirror along two axes. At the beginning of 2018, a decision was made to restore it with the creation of new optics and a control system. In 2021, the control system was made, and a temporary 350 mm telescope was fixed on the main tube of the telescope, which made it possible to start the first test and scientific observations. Automation of observations imposes increased requirements on the protection of the telescope from many factors. Therefore, the authors implemented a number of protective functions that exclude emergency situations without human. Scientific tasks: photometry and astrometry of a wide range of objects, alert observations (gamma-ray burst afterglows, gravitational-wave events), search operations (asteroids and comets, novae and supernovae, transients, etc.). In this paper, we present a detailed description of the restoration process, the modernization of the telescope, and the first results.
Show AbstractThe angular distributions of scattered neutrons in the n + 12C reaction are measured at an initial neutron energy of 14.1 MeV for the cases of elastic scattering and inelastic scattering to the first excited state (JP = 2+, E1=4.44 MeV) of 12C nucleus. The experiment was carried out within the framework of the TANGRA (TAgged Neutron and Gamma RAys) project, based at the Frank Laboratory of Neutron Physics of Joint Institute for Nuclear Research. To register neutrons, 20 plastic detectors were used, scattered neutrons of different energies were separated by the time-of-flight technique. The collected data were corrected using a Monte Carlo simulation of the experiment to take into account multiple scattering in the sample and the finite size of the detectors. The resulting angular distribution was normalized to the experimental data of other authors to obtain the absolute values, the differential scattering cross section.
Show AbstractThe main topik of the reserch is to find out is it possible to load fully PWR's and BN-800's cores without consideretion of disperse structure of MOX-fuel. Two types of lattice were considered for PWR and BN-800: homogeneous and heterogeneous. At first, the calculation was for pins. Each fuel pin was divided axially or radially into zones. Different number of plutonium agglomerates were simulated in each zone, the volume fraction was 7%, 10% and 22% for each model. The typical diameter of Pu-rich agglomerate was selected: 30 μm as an average value and 50 μm as a probable maximum. The focus of the study was on the following characteristics: energy distribution in plutonium agglomerates and in uranium matrix; Doppler effect; reproduction coefficient. In conclusion, the more volume fraction of Pu-rich agglomerates - the more energy release in pins, but agglomerates' diameters have no influence and also there is no dependence of axial partition.
Show AbstractThe aim of this paper is estimation of sensitivity of NA62 experiment towards the search for forbidden decay $\pi^{0}\rightarrow3\gamma$, which allows to test C invariance in electromagnetic interactions. Current upper limit of the probability of the decay is $3.1\times10^{-8}$ with $90\%$ confidence interval. $K^{+}\rightarrow\pi^{+}\pi^{0}$ decays are used as a source of $\pi^{0}$. The idea of selection of events with 3 products after $\pi^{0}$ decay in NA62 detector was developed. NA62 detector and all physical processes were modelled with Monte Carlo method using Geant4. Estimation of experiment sensitivity without consideration of background events is 1 order better, than current upper limit on the forbidden decay. Main background processes were studied. Main contribution in background events is $K^{+}\rightarrow\pi^{+}\pi^{0}, \pi^{0}\rightarrow2\gamma$ decay, when photon interacts with detector, and electron-positron pair is created. Specific veto was developed to suppress these background events. The signal region was selected. Comparison of Monte Carlo simulation and experimental data was done. The estimation of number of background events inside signal region was obtained. With strong selection criteria the lack of Monte Carlo events is observed. Analysis of background events is being continued in order to intensively generate more Monte Carlo events.
Show AbstractThe current paper is dedicated to the modeling of accelerator neutrino oscillation experiments using GNA software for investigating the sensitivities to the neutrino oscillation parameters. A unified shell based on an input configuration file was created. It can produce expected event rate spectra after neutrino oscillations and can calculate sensitivities to neutrino mass hierarchy, CP-phase and θ23 value. The NOvA experiment collected data since 2014 and a planned widescale experiment DUNE were chosen for sensitivity calculations. Event rates obtained in GNA were compared to official Monte-Carlo modeling of NOvA and DUNE collaborations. It was shown based on the sensitivities that NOvA rejects the inverted mass hierarchy for maximal CP-violation (δCP = −π/2) at a significance level above 5σ with 36 × 10^20 POT for the neutrino regime and 36 × 10^20 РОТ for the antineutrino regime exposure. It is shown that DUNE can determine the neutrino mass hierarchy for any possible δ CP phase values at 5σ significance level with an exposure of 1.1 × 10^21 POT/year for 2-3 years according the running staged plan. The DUNE sensitivity at 3σ for the CP-violation hypothesis is achieved for 50% of the values from a δCP range for 7 years of exposure. Based on the analysis of the Asimov data, the sensitivity of NOvA and DUNE to the rejection of the maximum value of mixing angle θ23 was obtained.
Show AbstractThe article describes the studies of rheological and filtration characteristics of low-permeability rocks of the Achimov deposits of the Urengoy gas-condensate field in the course of modeling the implementation of the method of directional unloading formation. The experiments were carried out on the Triaxial Independent Load Test System (TILTS) at the Institute for Problems in Mechanics of the Russian Academy of Sciences. The results of physical modeling of actually occurring stresses in the vicinity of the wells during application of the method of directional unloading formation are presented. The statistical analysis of the influence of the creep process on the permeability of the rocks under study is carried out. The patterns of changes in the filtration characteristics of the studied rocks of the Achimov deposits during the simulation of the implementation of the method of directional unloading are established. Based on the experimental studies, conclusions were made about ways of preventing negative processes in reservoirs and ways of increasing well productivity were outlined.
Show AbstractAvalanches of runaway electrons accelerated by an electric field in thunderclouds are one of the sources of Terrestrial Gamma-ray Frlashes (TGF). However, electrons produced in the avalanche process are not enough to describe TGF, which experimentally observed from space. Joseph Dwyer proposed a feedback model that increases the number of particles in avalanches. One of the key mechanisms in the Dwyer model is the gamma feedback, the contribution of which increases with the electric field strength. Gamma feedback is based on the phenomenon of reversal of photons of bremsstrahlung, which is formed during the acceleration of electrons in the cloud field. These photons can give new electrons at the beginning of the avalanche formation region, which leads to the formation of secondary avalanches. In this work, a criterion for the formation of infinite feedback due to the reversal of bremsstrahlung gamma quanta was derived.
Show AbstractThe aim of this work is mathematical modeling of radiation transfer in vegetation cover elements, the geometry of which is close to real, using a software implementation of the Monte Carlo method. Information about the radiation reflected by a plant is needed to model the photosynthetic activity of trees, and consequently to model the carbon dioxide fluxes absorbed or released by plants, which is one of the most important tasks of ecology. By definition, the Monte Carlo method is a method for modeling random variables and processes to calculate the characteristics of their distributions. The process of radiation transfer in inhomogeneous media is modeled as a random Markov chain of collisions of photons with matter, and the purpose of the Monte Carlo method is to find the average statistical characteristics of this process. In this work, a small branch of birch is used as an object. In connection with the possibility of using modern multiprocessor systems for calculations it becomes necessary to distribute calculations, which can significantly reduce the time of realization.
Show AbstractThis paper presents the results of a study of the stochastic differential equation stability used in the model of accumulation of gene mutations during the evolution of organisms. In the course of numerical implementation, the need was revealed to obtain a criterion that the parameters of the problem must be in order for the solution to remain within the boundaries determined by the physical meaning. To solve this problem, a study of the stochastic equation for stability according to Hyers-Ulam was carried out. The resulting criterion corresponds well with the numerical experiment.
Show AbstractThe paper presents and applies a modern, computationally efficient and economical numerical method for solving the Schrodinger equation in terms of constructing a several energy isomers of the neurotransmitter molecules glycine and dopamine in order to research their internal structure. A number of energy isomers of these molecules has been constructed, including both already known configurations and fundamentally new ones.
Show AbstractCurrently, hydrates are of considerable interest among researchers, which is due, firstly, to the use of gas hydrates as promising sources of hydrocarbon energy, and secondly, the possibility of using such molecular systems as reservoirs for hydrogen storage. The thermodynamic properties, formation kinetics, and phase diagrams of gas hydrates are well studied, as evidenced by a large number of experimental and theoretical studies. Despite this, questions remain open related to the lack of understanding of the mechanisms of structure formation and stability of molecular complexes of the «guest-host» type. In this work, within the framework of the density functional theory, some aspects of the structural stability of gas hydrates were studied. It is shown that the inclusion of a gas molecule in the hydrate cavity leads to repulsion of the cavity nodes, which indicates the structural stabilization of the hydrate. The binding energies were calculated for gases such as CH$_4$, C$_2$H$_6$, CO$_2$, Xe and H$_2$S placed in small (D-) and large (T-) cavities of clathrate hydrates. It was found that small CH$_4$, Xe, H$_2$S molecules stabilize D-cavities better, while large C$_2$H$_6$ and CO$_2$ molecules stabilize T-cavities of hydrates better. The densities of electronic states for the hydrate with/without the inclusion of a gas molecule are obtained. When a gas molecule is switched on, a shift in the energy of the electronic subsystem of the hydrate was found, which indicates a decrease in the total energy of the system and an increase in its stability.
Show AbstractIn this paper, we consider the possibility of studying the local atomic structure of a substance by analyzing extended fine structures of electron energy loss spectra (EXELFS - Extended Electron Energy Loss Fine Structure) using neural network technologies to determine the structure parameters: partial coordination numbers, chemical bond lengths and thermal dispersion parameters. The experimental data of EXELFS spectra of one-component systems obtained in the transmission mode were chosen as model objects. At the first stage of the work, the interatomic distance was chosen as the parameter to be determined, since minimal processing is required to obtain this characteristic from the initial experimental data. Various learning methods and types of neural networks are considered: supervised learning, unsupervised learning and reinforcement learning. The analysis of the work of researchers in the field of spectroscopy, solving various problems using machine learning methods, is carried out. The results of the operation of an additional module capable of analyzing the spectra of one-component systems are shown.
Show AbstractGeneration of magnetic fields in various cosmic objects is described using the dynamo mechanism. In the case of galaxies, one of the most effective models is the no-z approximation created for thin disks. It characterizes the field evolution by means of averaged values of parameters related to kinematic characteristics of the interstellar medium. Meanwhile, in the case of a number of active processes, it is necessary to consider significant fluctuations of these parameters, as well as vertical fluxes of the medium. In the present paper, the equations for dynamo in a thin disk with random coefficients are considered and various random perturbations of both astronomical and mathematical interest are investigated. The presence of intermittency is shown, where the higher moments grow faster than the lower ones. It is important to say that we used large random samples that are much larger than ones in previous works.
Show AbstractThis work is devoted to the study of nanostructures in terms of mechanical properties. We pay special attention to the behavior of nanostructures in the presence of roughness. Research in this area goes in three directions: 1) study of the features of the manifestation of roughness during the formation of nanostructures 2) development of methods for estimating the amount of roughness (amplitude, spatial frequency, fractal constant using SEM, AFM, speckle studies) 3) modeling of mechanical, temperature properties, electrophysical properties of silicon microelectronics elements based on the above nanostructures. This work is devoted specifically to modeling [1]. With the transition to the transverse dimensions of nanostructures below 100 nm, the issue of roughness control is becoming more acute, as the influence of geometric irregularities on the electrophysical parameters of devices increases [2, 3]. In addition, with a decrease in the ratio of width to height of fin nanostructures, plastic properties begin to express themselves more and more noticeably [4, 5]. We assume that during the formation processes, this dimensional effect can make a significant contribution to the expression of nanoscale roughness. We are taking the first steps to evaluate this contribution in this paper. As a result, graphical dependences of the stiffness of the fin structure were obtained at different values of the form factor, and the analysis of the natural frequencies of the structure was carried out.
Show AbstractIn this article, the tricalcium phosphate (TCP) material doped with gadolinium Gd3+ ions, which is extremely promising in orthopedics and dentistry due to its high biocompatibility with human bone tissue and the presence of such important properties as osteoconductivity and bioresorption, has been studied by electron paramagnetic resonance (EPR). To control each stage of healing and the degree of regeneration of hard tissues, it is necessary to use physical imaging methods (radiography, computed tomography (CT) and magnetic resonance imaging (MRI)) by introducing contrast agents (Gd3+) to the bone substitute TCP. In this study, it was unequivocally established that gadolinium with a valence of 3+ is embedded in the TCP crystal lattice without damaging it and without changing the local environment. Simulation of EPR spectra by different sets of fine structure parameters (crystal field) indicates the presence of two nonequivalent Gd3+ positions (at extremely low concentrations x = 0.001) with axial and lower symmetry. Low-field resonant absorptions with effective g-factors 5.9, 2.8 and 2 related to high-spin S = 7/2 centers in orientationally disordered samples were observed and identified.
Show AbstractScanning ion-conductance microscopy or scanning capillary microscopy (SICM) is one of the methods of scanning probe microscopy (SPM) based on the use of nanocapillaries. The main advantages of SICM over other SPM methods are a non–violent action on an object under study in the course of measurements and a possibility to conduct studies in the natural environment (in liquid). Therefore, this method has become widely used in biological and medical research. Today SICM can be used for multiparametric analysis of the object’s surface and processes occurring near it. In SICM bioapplications the most relevant areas of work are studies of living systems with a wide time resolution (from minutes to days) and development of methods for targeted agent delivery to the surface of the subject in order to study its response to external influences. This paper presents the results of a study of the morphology of human carcinoma cells and the life cycle of human blood cells using ion-conductance microscopy. SICM allows not only the visualization in a three-dimensional scale, but also provides an opportunity to process a number of experimental data for diagnostic purposes.
Show AbstractIn recent years, the possibility of using magnetic nanoparticles to ensure the transfer of medicines to areas affected by malignant neoplasms has attracted much attention of researchers. Such a solution can be organized by placing the nanodose of the drug in a polymer or protein shell with the addition of ferrite nanoparticles with high values of coercive force. In this case, it becomes possible to control the release of the drug due to local heating by a magnetic field. The paper considers the possibility of obtaining nanoscale ferrite particles for inclusion in such nanocontainers and experiments on their heating by an alternating magnetic field as part of various biocompatible suspensions. Particle sizes before and after machining in a high-energy ball mill were measured using scanning electron microscopy. The resulting nanoparticles were mixed with biologically compatible liquids such as rheopolyglucine and glycerin with the addition of polyethylene glycol. The chemical composition of the suspension was confirmed by Raman spectroscopy. During the experiments, the authors measured the deposition time of ferrite particles in suspensions. The resulting magnetic fluids were placed in an alternating magnetic field to determine the possibility of their heating. The results of the experiments allow us to talk about the prospects of using this technology to create nanocontainers.
Show AbstractThe effect of sol-gel synthesis (SGS) temperature on the structural, morphological and adsorption properties of 65%mol.[97%ZrO2–3%Yb2O3]–35%Al2O3 xerogels obtained in the presence of polymer at 10o (1), 25o (2), 60oC (3) and dried at 180oC was established in this work. The study of the X-ray amorphous hydrated xerogels by a complex of methods (TG/DSC, FTIR, SEM, XRD, SAXS, BET/BJH) showed their differences in the composition of surface complexes, morphology and size characteristics. Sample 3 had a different morphology, shape and size of pores from the other samples, this sample had the lowest activity in adsorption of dichromate ion from aqueous solution. The values of specific surface area and pore volume of xerogels decreased in the consequence of samples 1-2-3. A correlation between the specific surface of xerogels and the average volume of scattering particles determined by small-angle X-ray scattering (SAXS) was obtained also. The possibility of obtaining xerogels with monomodal distribution of heterogeneities ~ 7 nm and pores ~ 4 nm in radius, high values of pore volume ~ 0.326 cm3/g and specific surface area ~ 427 m2/g at TSGS =10oC was shown. The sample synthesized at 25oC was the best in quick removal of anionic Cr(VI) pollutant and adsorption per unit mass of the multi-oxide sorbent.
Show AbstractOptical microscopy is one of the most widely used and convenient methods of imaging samples without complex real-time preprocessing, with a resolution not available to the human eye. However, the resolution of any modern conventional optical microscope is limited by the diffraction limit, which is about 200 nm in visible light. To increase it, and to overcome this limitation, a microlens is proposed. A microlens is an optical lens that produces an image by 'capturing' light waves in the near field reflected from an object. Positioned between the specimen and the microscope objective, the microlens is an optical amplifier that enhances the resolution of the microscope. This paper presents the results of experiments on overcoming the diffraction limit in optical microscopy by using microlenses in a conventional optical microscope. The potential use of optical microscopes with microlenses lies in achieving new possibilities for imaging bacteria, viruses, DNA and biomacromolecules with a detailed real- time study of their inner structure.
Show AbstractBy numerically solving the Maxwell equations for the problem of light scattering on spherical silicon nanoparticles with diameters from 90 to 170 nm dispersed in water, including gold and silver nanoparticles deposited on them with diameters from 5 to 20 nm, the distributions of electric fields in the light spectrum were obtained. Absorption and scattering cross-sections in the spectral region from 300 to 900 nm were discussed. The conditions for the maximum enhancement of the electric field strength, which arise due to the coupled resonances of Mie scattering in silicon nanoparticles and localized plasmons in gold nanoparticles, including those in the near-infrared region of the spectrum, corresponding to the maximum region of biological tissue transparency, are revealed. The results obtained can be used in biosensorics and biophotonics.
Show AbstractDespite the large number of works on Raman spectroscopy of human hair, there is a lack of information about the methodology of experiments and the reliability of the data obtained. There are various experimental configurations in which the sample is positioned differently relative to the exciting radiation, and the published spectral data differ from each other. The question arises about the influence of the sample orientation on the measured Raman spectra. We compare the Raman spectra of a human hair measured in horizontal (exciting beam is perpendicular to the hair axis) and vertical (exciting beam and hair are coaxial) configurations. Along with the differences in the spectra, which result from molecular changes, the differences related to the polarization sensitivity of hairs were identified. To obtain cross-sections of the hair, we have developed the method based on freezing the sample in liquid nitrogen, which does not require microtomes and fixing agents.
Show AbstractIn the present paper, we study the mechanism of interaction of twisted photons with helically symmetric dielectrics. In the framework of quantum electrodynamics in a dispersive medium, the problem of scattering of twisted photons by a slab made of a helical medium is solved. High orders of perturbation theory are considered. The selection rules for the scattered wave are revealed. It is shown that the medium imparts a longitudinal momentum to the photon as well as an additional projection of the total angular momentum onto the axis of helical symmetry of the medium. It is shown that the selection rules are satisfied for all orders of the perturbation theory and, therefore, are valid in the nonperturbative regime, i.e., they are a general property of the scattering of electromagnetic waves on plates made of a helical medium placed into a homogeneous isotropic transparent dielectric.
Show AbstractA theoretical study of the dynamics of energy exchange in a two-level system consisting of a spherical nanoparticle with a dielectric core and a metallic shell and a quantum dot in the weak confinement mode is carried out. The system geometric parameters are determined at which the interaction of the Vanier-Mott exciton of a quantum dot with the electric field of localized plasmons of a nanoparticle becomes strong. It is shown that with an increase in the intensity of the plasmon-exciton interaction, the nature of the kinetics of energy transfer between the components of the system changes from aperiodic attenuation to damped oscillations.
Show AbstractCurrently, quantum technologies based on the phenomena of quantum physics have acquired particular importance. Now it is one of the most promising areas of science and technology, relating to end-to-end digital technologies. Graduates of the areas "Infocommunication Technologies and Communication Systems" and "Photonics and Optoinformatics" should receive basic knowledge and skills in this promising area, therefore, Prof. M.A. Bonch-Bruevich SPbSUT is actively working to introduce disciplines related to quantum technologies into the curricula. These disciplines require a laboratory workshop. This paper presents a virtual laboratory installation for studying the effect of a quantum eraser, simulating an interference experiment that demonstrates the influence of an observer on the behavior of quantum objects.
Show AbstractIn connection with the advent of optoelectronic devices using various applications of modern photonics, ranging from light collection by nanophotonic waveguides to quantum information processing, the study of nanocrystalline photonic structures is of particular relevance. This paper presents the results of studying the dependence of the dispersion characteristics of quasiparticle excitations in a nonideal one-dimensional (D) lattice of micropores containing quantum dots in one of the sublattices on the concentration of structural defects associated with the variation in the positions of micropores. It is shown that as a result of the presence of these structural defects in a 1D two-sublattice array of micropores, it is possible to achieve the necessary change in the energy structure of electromagnetic excitations and, consequently, the optical properties of the system under study, due to the rearrangement of the electromagnetic spectrum. Within the framework of the virtual crystal approximation, we numerically simulate the dependence of the dispersion characteristics of quasiparticles (polariton excitations) in a nonideal two-sublattice chain of tunnel-coupled micropores (resonators) in the case where one of the sublattices of the chain contains quantum dots as an atomic subsystem. The result obtained in the study of the dependence of the effective mass of electromagnetic excitations on the concentration of structural defects opens up the possibility of controlling the group velocity of these elementary excitations, and, consequently, the signal transmission rate in the corresponding optoelectronic device.
Show AbstractA quantum frequency standard is necessary to accurately measure the frequency of oscillations or generate oscillations with a time-stable frequency. An important functional node in the cesium atom frequency standard is the frequency synthesizer. The paper presents a new frequency synthesizer circuit based on the direct digital synthesis method. The advantages and disadvantages of the new signal synthesis method are considered in detail, the differences between this method and others are indicated. The description of the main nodes of the new synthesizer circuit is given. By increasing the bit depth of the accumulating adder, we achieved a reduction in the step of tuning the output frequency by several orders of magnitude. It is concluded that this method satisfies all the requirements for the parameters of frequency synthesizers.
Show AbstractSilicon is considered as perspective material for test masses in some projects of future gravitational-wave detectors. Electrostatic actuators are suggested for precise correction of test masses' position. Electric field of actuators will cause additional mechanical loss and corresponding thermal noise of their position, because of finite value of silicon resistivity. The experimental setup developed allows us to investigate this loss in temperature range 100-300 K via a model comprises silicon disc resonator and an electrode plate situated nearby. The dependence of additional mechanical losses induced by electrostatic field on the resistivity of silicon was obtained. These results would be useful while estimating additional losses, arising from action of actuator's electric field on test masses and corresponding noise.
Show AbstractThis work is devoted to a wireless power transfer in magnetic resonance imaging (MRI) at a higher-order mode of a birdcage resonator. A numerical model of the resonator with a phantom and the Siemens Avanto 1.5 T clinical MRI scanner have equal parameters. We use two orthogonally located loop antennas as a system of receiving antennas. In the course of numerical simulations of the voltage on the receiving antenna system, electric and magnetic field distribution, and the specific absorption rate (with a detailed voxel model of a human), we found that the optimal mode is at a frequency of 44.2 MHz. Ways of the practical application of the wireless power transfer system presented.
Show AbstractAn inexpensive, high-precision synthesizer with a low level of phase noise was experimentally developed and implemented in the frequency range of 55-65 GHz at a power of 3 mW. The line width was less than 1 Hz, which depends on the line width of the reference frequency generator. Since the frequency of the backward wave oscillator is controlled by changing the input voltage, frequency stabilization has been achieved by using phase locked loop. Stability is determined by the reference oscillator and ranges from 1Hz (Short-term stability) to 100Hz (Long-term stability). А low division ratio is required to reduce phase noise, so a sub-harmonic mixer was used to down-convert the high frequency to a low intermediate frequency. The results obtained open up the possibility of measuring the properties of small materials using open resonators and make it possible to create a high-precision stable generator with a low level of phase noise in the terahertz range.
Show AbstractIn this work, we investigated the mechanisms of corona discharge impact on the surfaces of weakly conductive media and conducted experiments to study the effectiveness of corona discharge applications in agriculture and animal husbandry. In particular, we have carried out experiments on the effects of corona discharge to remove ammonia vapors in the air, and to remove mold from the surface of infected grains. The results obtained showed that the corona discharge was effective in eliminating ammonia in the air, up to 2.5 times over a period of 15 minutes. In experiments to study the removal of the fungus from the surface of the grains of agricultural crops using a corona discharge, the results of its almost complete removal from the surface of the grains were achieved with processing times up to 3 hours.
Show AbstractBased on the method of equivalent substitutions and the method of coupled wave thicknesses, a numerical analytical solution to the problem of calculations of the thickness values of the interference anti-reflective structure ("π structure") for an arbitrary number of layers is obtained. Exact algorithm is obtained that make it possible to synthesize antireflection structures providing a predefined reflection coefficient on the entire continuous set of values from 0 to 1 for any real values of the refractive indices of both matched media and materials of layers of such structures. The correctness of the obtained algorithm and the efficiency of the method are confirmed by a numerical experiment.
Show AbstractCarrier scattering processes in Bi1.08Sn0.02Sb0.9Te2S(BSSTS) topological insulator (TI) were studied using two independent methods: four-probe resistance measurements together with nonresonant microwave absorption (NMA). We obtained temperature dependences of resistance and NMA amplitude of BSSTS thin flakes. At low temperatures (T<100 K) BSSTS resistance behavior is determined by contribution of metallic topological surface states. The comparison of the results obtained by both methods allows us to make a conclusion that scattering time is larger than measurement frequency. It implies that scattering events are rare and gives indirect evidence of weak antilocalization effect. To study this phenomenon, we obtained magnetic field dependences of resistance and NMA of BSSTS. Results exhibit clear evidence of weak antilocalization contribution to TI conductivity. Analysis of the results allowed us to estimate phase coherence length lϕ at 1.5 K and 4.2 K temperatures. Obtained values of lϕ are close to 400 nm and relatively high in comparison with similar bismuth chalcogenide compounds. That makes BSSTS attractive for future applications at spintronics.
Show AbstractNowadays one of the most promising methods for creating electronic charge sensors with subelectronic sensitivity and wide range of operating temperatures is the fabrication of a semiconductor nanowire. These are required for operation of such a device as an efficient, fast and inexpensive charge-type DNA sequencer. The aim of this work is to develop and manufacture electric charge sensors based on silicon nanowires with a thickness of less than 20 nm and a width of 30–50 nm with platforms formed on them for the immobilization of single molecules of DNA polymerase. The samples were fabricated on SOI substrates using photo- and electron lithography, ion-plasma etching and liquid etching, magnetron and electron beam sputtering. The formation of extremely small silicon nanowires with sites for the immobilization of polymerase molecules was implemented in three ways: 1) deposition of a single golden dot on a nanotransistor as a result of their exact alignment when the dot exposed; 2) formation of a single golden area and a nanowire channel by the shadow evaporaton method; 3) deposition of an extremely thin discontinuous granular gold film on the area of nanowire formed. Measurements of electron transport through fabricated nanotransistors showed that their resistances, which lie in the range of 1–2 GΩ, strongly depend on the gate voltage. The charge sensitivity of the sensors is less than 1 e/Hz^(1/2). According to estimates, this sensitivity is sufficient to detect a release of a proton upon insertion of a single nucleotide into DNA.
Show AbstractComposite materials based on a system of porous silicon nanowires and gold and nickel oxide nanoparticles are investigated by impedance spectroscopy methods. It was shown that composites based on silicon nanowires and nickel oxide are characterized by a fractal structure, for composites based on nanostructured silicon and gold at room temperature there is an effect of moisture accumulation.
Show AbstractA study of sensor coatings based on zinc oxide nanorods with activation of gas sensitivity to isopropyl alcohol vapor by irradiation in the ultraviolet and visible regions of the spectrum is presented. It is shown that irradiation with an ultraviolet LED with a peak wavelength of 370 nm ensures the gas sensitivity of the sensor coating to isopropyl alcohol vapor at room temperature. Reducing the power consumption of the LED to 100 mW by increasing the duty cycle of the supplied voltage at a pulse period of 2 ms leads to an insignificant decrease in sensitivity. It has also been shown that the combination of heating up to 150°C with ultraviolet irradiation of the sensor coating leads to an increase in response. To activate gas sensitivity in the visible range, zinc oxide nanorods were decorated with colloidal AgInS2 quantum dots. It has been shown that zinc oxide and colloidal AgInS2 quantum dots with a shell of mercaptopropionic acid form a heterojunction, and decoration of zinc oxide nanorods with colloidal quantum dots provides sensitization of zinc oxide to irradiation in the visible region. Sensitization of ZnO nanorods with colloidal AgInS2 quantum dots provided gas sensitivity to isopropyl alcohol vapor at room temperature under illumination with a peak wavelength of 460 nm.
Show AbstractSemileptonic flavor changing neutral current transitions with a pair of neutrinos in the final state are very accurately determined in the standard model (SM) and thus provide an accurate and sensitive probe for physics beyond the SM. Until recently, the poor tagging efficiency for the $B\to K^{(*)}\nu\bar{\nu}$ modes made them less advantageous as a probe of new physics (NP) compared to the charged lepton counterparts. The most recent Belle II result on $B^+\to K^+\nu\bar{\nu}$ uses an innovative inclusive tagging technique resulting in a higher tagging efficiency; this together with previous BaBar and Belle results indicates a possible enhancement in the branching fraction of $B^+\to K^+\nu\bar{\nu}$. A reanalysis of the full Belle dataset together with upcoming Belle II dataset is expected to result in a much more precise measurement of this mode. If the branching ratio is indeed found to be enhanced with improved measurements, this would provide an unambiguous signal of NP without uncertainties due to long-distance non-factorizable effects or power corrections (in contrast to $B\to K^{(*)}ll$). We have explored the possibilities of such an enhancement as a signal of NP within scenario dicribed on \cite{1} which can also explain some of the other tensions observed in neutral as well as charged current B-decays.
Show AbstractNeutrino oscillations in a magnetic field are considered in the framework of the perturbative quantum field-theoretical approach with the distance-dependent propagator. This formalism is applied to describe the specific processes of solar neutrino oscillations, the extension and inhomogeneity of the source, which is the core of the Sun, are taken into account. Asymptotic formulas are obtained for the probability of neutrino oscillations in cases where neutrinos are detected through the weak charged- and neutral-current interactions. It is shown that the results obtained are in good agreement with the results of experiments on measuring the solar neutrino flux.
Show AbstractIncreasing precision of measurements and observations of excesses at the Large Hadron Clddider require accurate calculations of the SM-like Higgs boson mass in different MSSM regimes with masses of the CP-odd Higgs boson larger and smaller than the mass of top-quark. It is found that while the contributions from radiative corrections to the dimension-six operators of the effective Higgs potential can be neglected at $m_A > m_t$, their contributions at $m_A < m_t$ open the possibility of scenarios with a light pseudoscalar. The values of model parameters in such scenarios are $M_S$=1--2 TeV, $\tan \beta$=2--5, $A_{t,b}, \mu \gtrsim M_S$ which satisfy the conditions of vacuum stability, perturbative unitarity, and the alignment limit.
Show AbstractA phenomenological approach to the construction of a relativistic model of thermo-visco-elasticity is elaborated. The main element of presented approach is the generalized Burgers equation. As a key step, we have constructed a non-local generalization of the Israel-Stewart model for relativistic causal thermodynamics of a homogeneous, isotropic cosmic fluid, in which the coefficient at the integral operator is responsible for the elastic properties of the medium. Based on the second low of thermodynamics we derive the integro-differential equation for the evolution of non-equilibrium pressure scalar and we show that the differential version of this equation is a relativistic analog of the Burgers equation describing visco-elastic processes in classical media. Based on the obtained equations for a medium model with bulk visco-elasticity, we present a hypothesis that the equations for a model with shear visco-elasticity can also be represented using the corresponding relativistic generalization of the Burgers equation; in other words, the equation for the traceless shear part of the non-equilibrium pressure tensor was obtained phenomenologically using an analogy with the exact equation for the bulk part of this tensor.
Show AbstractThe effect of sublattice symmetry breaking in the extended Hubbard model on the position of semimetal-antiferromagnet phase transition is considered. It is shown that setting different values of on-site interaction intensity on the sublattices leads to a shift of the phase transition point. The formation of spin condensate on sublattices is discussed. Changes in kinetic and potential energies of electrons are demonstrated.
Show AbstractWe consider general procedure for including Stueckelberg fields with reducible gauge symmetry. It is shown that this procedure allows one to construct higher derivative dual formulations for representations of massive spin 1 and spin 2 fields. In particular, we demonstrate that massive spin 1 can be described by the antisymmetric second-rank tensor, and massive spin 2 can be represented by the traceless fourth-rank tensor with the Young tableau of window type. It is also shown, that by the choice of gauge fixing conditions in the Stueckelberg action we can switch between different dual formulations of the same theory.
Show AbstractField transformation rules of the standard fermionic T-duality require fermionic isometries to anticommute, which leads to complexification of the Killing spinors and results in complex valued dual backgrounds. We generalize the field transformations to the setting with non-anticommuting fermionic isome- tries and show that the resulting backgrounds are solutions of double field theory. Explicit examples of non-abelian fermionic T-dualities that produce complex and real backgrounds in Minkowski space-time are given. Some of our examples can be bosonic T-dualized into usual supergravity solutions, while the others are genuinely non-geometric. There is sort of classification of geometric and non-geometric solutions in this case and their correspondence with dual time.
Show AbstractWe propose a method for constructing equations of generalized 10D supergravity using non-unimodular bi-Killing Yang–Baxter deformations. The presented approach is generalized to the 11-dimensional case. Using non-unimodular three-Killing generalized Yang–Baxter deformations, a generalization of the equations of 11D supergravity is obtained.
Show AbstractFor the classes V and VI of the Bianchi models, which describe the evolution of an anisotropic spatially homogeneous early Universe with a global magnetic field, the problem of the formation of an electric field induced by the interaction of photons with axionic dark matter is studied. The problem is investigated within the framework of the author's version of nonlinear axion electrodynamics. It is shown that only for a particular Bianchi-VI0 model the symmetry of the magnetoelectric field configuration is consistent with the spatial symmetry of the model. For the model of this type, the exact solutions of the electrodynamic equations are found, and it is established that the evolution of the axionically induced electric field can be accompanied by its anomalous growth.
Show AbstractIn the Standard Model (SM), the $b \to s$ and $b \to d$ flavor-changing neutral currents (FCNC), being loop-induced, are standard experimental channels for testing the SM precisely and searching for possible physics beyond the SM. Purely annihilation decays of $B$-mesons are of significant interest as they are extremely suppressed in the SM and New Physics effects can increase substantially their decay widths. Radiative and semileptonic decays with the $\phi$-meson production, being a subject of experimental searches at the LHC and KEKB, are typical examples of annihilation-type processes. In the paper, the annihilation-type semileptonic $B^0 \to \phi \ell^+ \ell^-$ decay, where $\ell$ is a charged lepton, will be discussed, and SM theoretical predictions without including contribution from $\omega$-$\phi$ mixing for the branching fraction based on the effective electroweak Hamiltonian approach will be given. The dependence of the branching fraction on the choice of models of the $B$-meson distibution amplitude included in the branching fraction by means of the first inverse moments is investigated. The total branching fraction of the decay $Br\sim 10^{-12}$ is three orders of magnitude less than the limit obtained by the LHCb collaboration, however, there are mechanisms for increasing this value that require further research.
Show AbstractWe present the preliminary results on the study of the cross sections for charmonium pair and bottomonium pair production in a single boson $e^+e^-$~annihilation. Processes have been studied in a wide range of energies, which are to be achieved at future $e^+e^-$~colliders, such as ILC and FCC. The contribution of color singlets states to production of vector and pseudoscalar states have been taken into account. Both QCD and EW production mechanisms have been considered including their interference and one-loop QCD correction. Cases of both intermediate bosons have been investigated: $\gamma$ and $Z$. All the calculations were performed in terms of perturbative technique and NRQCD-factorization.
Show AbstractMasses of the ground and excited states of tetraquarks, composed of charm $c$ and bottom $b$ quarks and antiquarks, are calculated in the relativistic quark model based on the quasipotential approach and quantum chromodynamics. Relativistic effects are consistently taken into account. A tetraquark is considered as a bound state of a diquark and an antidiquark. The finite size of the diquark is taken into account, using the form factors of the diquark-gluon interaction. It is shown that most of the investigated states of tetraquarks lie above the decay thresholds into a pair of quarkonia, as a result they can be observed as broad resonances. The narrow state in the $J/\psi$ meson pair production spectrum recently discovered by the LHCb collaboration at Large Hadron Collider corresponds to the excited state of a fully charmed tetraquark.
Show AbstractThe surface energy-momentum tensor was obtained for the action of an ideal fluid with a variable number of particles in Euler variables. It is shown that in the absence of external fields, “external pressure” and “external flow” are associated with the production of particles in a double layer. The equations of motion along with the Lichnerowicz conditions are expressed using invariants of spherical geometry for timelike and spacelike spherically symmetric singular hypersurfaces. It is shown that for spherically symmetric thin shells the two-dimensional scalar curvature and the two-dimensional Laplacian of the radius are continuous. Spherically symmetric timelike and spacelike singular hypersurfaces separating two solutions of spherically symmetric conformal gravity are investigated as applications, in particular, various vacua and Vaidya-type solutions are used.
Show AbstractAim: to study the morphology of the supernova remnant RX J0852.0-4622 in different wavelength ranges to determine the distance to the object and its age. Materials and methods: in the work were used data on the radiation of RX J0852.0-4622 in extreme ultraviolet at a wavelength of 83 Å, obtained by the EUVE satellite. To calculate the photon counting rate from the remnant, a program was written that allows the required processing of files in the FITS format. The calculation of the UV radiation flux was carried out using the PIMMS software. The morphology of the remnant was determined from its images in the UV, X-ray, radio and gamma bands. Results: the flux of extreme UV radiation from RX J0852.0-4622 takes values in the range 2.128-6.390 photons sm^(-2) s^(-1). The morphology of the supernova remnant RX J0852.0-4622 has a bipolar structure: a two-ring structure has been revealed. Distance to Vela Jr.: 275 parsecs, age of the remnant: 600-1200 years. Conclusion: the calculated flux of extreme UV indicates the close location of the object relative to the Earth. The obtained values of the distance to the remainder of RX J0852.0-4622 and its age indicate that Vela Jr. is an extremely close to Earth young supernova remnant.
Show AbstractThe optical distortions of the SPHERA series of telescopes have been studied. A spherical mirror creates on the mosaic of the telescope an image which is distorted, compared to the shape of the portrayed object. The farther from the axis of the mirror the object is, the greater the distortion becomes. In fact, there is a compression of the image space in the radial direction. These distortions prevent further processing of the EAS images registered by the PMT mosaic of the telescope. It becomes necessary to compensate for these distortions of the images in order to bring their shape closer to the shape of the objects that are being depicted, in our case - the spots of Cherenkov light on snow from EASs.
Show AbstractThe approximation function that makes it possible to describe the lateral distribution function of Cherenkov light of individual extensive air showers from various primary nuclei with energies of 1-100 PeV and zenith angles up to 20 degrees with an accuracy better than 5\% in the distance range 0-500 meters from the shower axis was found. Initially the approximation was intended for processing the events of the SPHERE-2 experiment, but its can also be applied to any experiment that uses the spatial distribution function at the level of the Earth's surface. A comparison was made with a simpler approximating function used in the SPHERE-2 processing and with the function used by the TAIGA experiment.
Show AbstractThe phenomenological model that predicts the behavior of a magnetic material near a first-order phase transition under the simultaneous action of several generalized forces: magnetic field, temperature, and external pressure, is presented in this article. Today, there is a variety of such models, based on the classical thermodynamic approach developed by Bean and Rodbell in 1962. One of their main disadvantages is the use of a linear approximation of the Curie temperature dependence on the crystal lattice volume the change. As consequence, this limits applicability of the previous models in a narrow range of temperatures and external pressures. According to the emerging paradigm, when creating a basically new generation of magnetic refrigerators, it is supposed to adjust the phase transition temperature of the working bodies in a wide temperature range down to cryogenic. The latter will require the application of high pressures up to 1 GPa. The prediction of material behavior under such extreme conditions required refinement of the constructed models: taking into account the phonon contribution to the Gibbs potential of the system, and processing the influence of external pressure on the behavior of the material. The constructed model made it possible to predict changes in the Curie temperature under the simultaneous applying of external pressure and magnetic field, to estimate the value of internal hysteresis within phase transition, and to determine the required value of external pressure to minimize the field hysteresis during the isothermal process of magnetization - demagnetization.
Show AbstractCurrently, electrically conductive polymers created at the end of the 20th century attract the attention of researchers due to the variety of their mechanical and optical properties, as well as their high conductivity. The most noteworthy polymer is polydiphenylenephthalide - PDP. An analysis of the existing data has shown that by now quite a lot of information has been obtained on the physical properties of PDP samples, but there are practically no data on the effect of the polymer, which is part of composite multilayer magnetic systems, on their magneto-optical properties. In addition, of particular interest is the study of the previously unexplored spectral dependences of the equatorial Kerr effect (TKE) for three-layer Fe/PDP/Fe systems, which can be used to obtain information about the electronic and magnetic structure of the samples. It should be noted that the magnetic characteristics and features of the magnetic field behavior of Fe/PDP/Fe systems were studied and published by the authors of this work earlier in the journal Solid State Physics, volume 60, issue № 9., P. 1693. At the same time, the magnetooptical properties of these systems have practically not been studied. Taking this fact into account, the present work is devoted to the magneto-optical study of three-layer Fe/PDP/Fe low-dimensional thin-film magnetic systems. This paper presents for the first time the results of a study of the magneto-optical properties of three-layer Fe/PDP/Fe low-dimensional thin-film magnetic systems. The measurements were made on a magneto-optical magnetometer using the equatorial Kerr effect. It is found that the values of the saturation field observed for the studied thin-film systems depend on the thickness of both the iron layer and the PDP layer. This fact is explained by the interaction of ferromagnetic layers with PDP layers. It is found that the shape of the spectral dependences of the equatorial Kerr effect observed for Fe/PDP/Fe thin-film systems with an iron thickness of 30 nm is similar to the magneto-optical spectra found for ferromagnetic films. At the same time, the magnitude of the magneto-optical effect depends on the thickness of the PDP layer; in particular, it decreases with an increase in the thickness of the PDP layer. This fact is explained by the decrease in the influence of the ferromagnetic metal layer on the magneto-optical signal with an increase in the thickness of the non-ferromagnetic layer.
Show AbstractThe specific absorption rate of electromagnetic energy is the most important parameter to characterize the efficiency of the heating process during magnetic hyperthermia. Further improvements in the efficiency of converting electromagnetic energy into thermal energy are not possible without a deep understanding of the physical mechanisms of energy conversion and the development of new methods to increase SAR values. The purpose of this work is to experimentally investigate the dependence of the SAR value on the magnetic field amplitude of ZnMn ferrite magnetic nanoparticles (MNPs) and reveal the contribution of the non-zero hysteresis loop width to the heating of the MNPs. MNPs of ZnMn ferrite were obtained by chemical co-precipitation. Experimental studies conducted have shown that in large MNPs, the behavior of SAR values changes significantly with increasing electromagnetic field (EM) amplitude, which is related to the change in the rate of area increase. The hysteresis loop increases with increasing EM field amplitude. This allows us to conclude that the hysteresis heating mechanism dominates in large MNPs, and that MNPs larger than 13 nm are not less promising than small superparamagnetic particles (<10 nm). Considering the Brezovich limitation, choosing a field value at the 100 Oe level is more suitable for clinical practice using MNP data.
Show AbstractIn this work, we study solid solutions of the system $(1-x)$Pb(Fe$_{1/2}$Nb$_{1/2}$)O$_3$—$x$Pb(Fe$_{2/3}$W$_{1/3}$)O$_3$ using X-ray diffraction and Mössbauer spectroscopy. To obtain solid solutions, we used the method of two-stage solid-phase synthesis and sintering according to conventional ceramic technology. Pure solid solutions of the$(1-x)$Pb(Fe$_{1/2}$Nb$_{1/2}$)O$_3$—$x$Pb(Fe$_{2/3}$W$_{1/3}$)O$_3$ system have been obtained. A deviation of the cell parameters from the Vegard rule was revealed, which indicates the stratification of the structure into microregions differing in composition. The clustering of Fe$^{3+}$ ions in the B-sublattice has been find. The introduction of PbFe$_{2/3}$W$_{1/3}$O$_3$ into the system leads to partial ordering of cations in the B position was shown.
Show AbstractThe article is devoted to the experimental study of the heat capacity of CP (T) inorganic VII-type clathrates: SrNi2P4 and BaNi2P4 in a low-temperature range 2 – 300 K. The studied compounds were synthesized using a two-stage ampoule method. The observed diffuse maximums CP(T) about 5 k are associated with the influence of two-level systems in the sublattice of guest atoms. Joint analysis of temperature dependencies of heat capacity and unit cell volume of both clathrates within the frames of the Debye–Einstein model allowed determining characteristic temperatures of the clathrate frameworks and guest atoms as well as parameters of the two-level systems. The relationship of the obtained parameters with the features of the crystalline structures of the VII-type clathrates is also discussed.
Show AbstractSingle-photon detectors, including those that resolve the number of photons, play a key role in experimental research in the field of quantum optics and quantum computer science. However, such detectors have a number of disadvantages, and the choice of a detector is always a trade-off [1] between such characteristics as quantum efficiency, dead time, etc. In view of this, part of the information is lost and distorted during measurements, which negatively affects the experimental data obtained. The study suggests method for tomography of photon-number-resolving single-photon detectors. By means of the proposed method, the main characteristics of detectors and radiation sources are restored. The proposed method are tested on the simplest models.
Show AbstractUsing the GEANT4 software package, the process of radiation sterilization of bone samples was simulated for the two most common sources - the flow of gamma rays and accelerated electrons. It is shown that during sterilization by gamma quanta, even at a low initial energy of the flux (0.5 MeV), there is a high degree of uniformity in the distribution of the absorbed dose, and as a result, the uniformity of the resulting sterilizing effect. At the same accelerated electron beam energy, the main part of the absorbed dose falls on the surface region. Increasing the electron beam energy to 3 MeV makes it possible to obtain a more uniform distribution of the absorbed dose over the volume of the bone fragment, and the use of bilateral irradiation provides an effective sterilizing effect even on the central region of the implant. The results obtained made it possible to reveal the regularities in the formation of the pattern of the distribution of the absorbed dose depending on the parameters of the electron beam, the conditions and geometry of the irradiation process and, on this basis, to develop practical recommendations for optimizing the modes of radiation treatment of a bone implant using fast electrons. This will ensure uniform processing of bone fragments with dimensions typical for use in bone grafting.
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