Issue 3, 2024
Ultra-high energy cosmic rays: sources, acceleration processes and GZK phenomena
Ultra-high energy cosmic rays: sources, acceleration processes and GZK phenomena
P. V. Alexandrovna$^1$, T. I. Yurievicn$^2$
Ultra-high energy cosmic rays (UHECR) reach an energy of 1020 eV, which is a million times higher than the energy achieved in artificial particle accelerators. The arrival of high-energy particles from space occurs infrequently, so detectors with a large area are required to register such events. It is necessary to understand what known effects can accelerate and decelerate particles to such energies. The upper energy limit is the Greisen-Zatsepin-Kuzmin (GZK) effect. This process significantly limits the possible distance to sources, and it should lead to suppression of the high-energy part of the spectrum. This work analyzes the GZK effect for nuclei from hydrogen to iron
Show AbstractModeling the effect of low-energy N2+ ions on MoS2 monolayers
Modeling the effect of low-energy N2+ ions on MoS2 monolayers
A. A. Solovykh$^{1,2}$
Quasi-two-dimensional molybdenum disulfide is a promising semiconductor material for creating nanoelectronics elements due to the fact that the width of its band gap can be changed by applying mechanical stresses, exposure to an electric field, as well as doping, which can be carried out during processing. However, since plasma ions can lead to degradation of the material and the appearance of undesirable structural changes, it is necessary to carefully investigate the mechanisms of their interaction with the material, the resulting effects and the degree of damage to the films. In this paper, the effect of N2+ ions with an initial energy E0 from 5 to 30 eV on a MoS2 monolayer for various impact regions and initial orientations of incoming particles was studied with the help of density functional theory (DFT) dynamic modeling with molecular dynamics algorithms. The results showed that N2+ ions with an initial energy of E0 ≤ 15 eV do not create permanent defects and are reflected from the surface, while particles with energy of 20-30 eV cause modification of the material and the formation of defects in it. The presented results can be used for optimization of the quasi-two-dimensional MoS2 samples processing technology with N2 plasma.
Show AbstractDigital core analysis: change of filtration-capacity properties of UGS reservoir after geomechanical impact
Digital core analysis: change of filtration-capacity properties of UGS reservoir after geomechanical impact
V. V. Khimulia, S. O. Barkov
In this paper we present the results of a series of comprehensive studies of residual changes in the filtration-capacitance properties of reservoir rocks of an underground gas storage facility caused by the impact of a non-uniform stress field during modeling of controlled pressure changes at the bottomhole. As part of digital studies of core material, multi-scale CT-images were obtained, on the basis of which three-dimensional models of rock pore space were created, homogeneity of rock structure and composition was analyzed, followed by geometric and statistical analysis of pore space, as well as numerical modeling of filtration processes in the rock to estimate permeability before and after mechanical tests. Measurement of porosity, geodesic tortuosity of pore space, estimation of pore size distribution, and analysis of rock filtration properties were performed. Spatial distributions of filtration flow velocities and pressure gradient changes were plotted. Within the framework of geomechanical tests, the study of rock deformation and filtration processes under the action of real stresses occurring in wells under controlled change of pressure in the well was carried out. The tendency to insignificant decrease of values of open porosity, permeability and pore geometry after non-uniform triaxial loading is shown. Conclusions about homogeneity and high connectivity of the pore space of the rocks under consideration are made. The absence of significant irreversible changes in the filtration-capacitance properties of rocks is shown. The characteristics obtained as a result of numerical analysis showed very good agreement with the results of field and laboratory measurements. The results of the work and the applied techniques can be used in the creation and adjustment of reservoir models, as well as in the development of an operational model of UGS. The presented technique of CT-data analysis allows to simplify data acquisition on core material characteristics, as well as to expand the results of laboratory and field studies of reservoir properties.
Show AbstractNumerical modeling of two- and three-phase equilibria of mixtures of hydrocarbons and carbon dioxide
Numerical modeling of two- and three-phase equilibria of mixtures of hydrocarbons and carbon dioxide
D. V. Selezneva
In the modern oil and gas industry, there is an increasing interest in the technology of injecting carbon dioxide into the reservoir. This method has become widespread not only because of its positive impact on the environment, but also because of its effectiveness in increasing oil production. When dissolved, the gas is able to lower the viscosity of the oil and, consequently, accelerate its flow. However, the effectiveness of the method depends on the phase behavior of mixtures of carbon dioxide and oils, the density and viscosity of the phases, and much more. In this paper, the method of direct energy minimization is used, which consists in finding the minimum value of the Gibbs energy for a system at constant temperature, pressure and composition.
Show AbstractSpectral characteristics of acoustic emission sources in rocks
Spectral characteristics of acoustic emission sources in rocks
R. A. Pashchenko
The work is devoted to the study of the spectral characteristics of acoustic emission sources (AE) in rocks. The analysis of data from previously conducted experiments on sandstone and granite samples was carried out in order to analyze acoustic signals arising from mechanical stresses and determine their compliance with seismic processes. The paper describes the calibration of the system, analyzes the consideration of wave attenuation and geometric factors. The main task of the study was to determine the corner frequency for estimating the size of the radiator cracks. During the analysis, it was found that for 99% of the events, the corner frequencies were not detected in the range of 100-1250 kHz. The remaining 1% of events produced corner frequencies of the order of 1080 kHz for sandstone and 975 kHz for granite, which corresponds to maximum crack sizes of 0.5 mm and 1 mm, respectively. The results demonstrate the need for further research and adjustments of techniques to improve measurement accuracy and understand the physical nature of spectral characteristics.
Show AbstractInvestigation of prognostic anomalies of induced seismicity in the Koina and Varna reservoirs.
Investigation of prognostic anomalies of induced seismicity in the Koina and Varna reservoirs.
A. I. Polovnikova
Seismic activity is one of the most dangerous and unstable natural phenomena on our planet. Research in the field of seismology is of great importance for minimizing the risks associated with earthquakes and improving the quality of their forecast. Induced seismicity refers to earthquakes that are caused by human activity. An example of such activity is the construction and use of hydraulic structures, such as dams or reservoirs. During the preparation of strong earthquakes, the distribution of seismic events in the space-time domain and their energy spectrum changes. Such changes are called anomalies of the seismic regime, they can be detected by analyzing the parameters of seismicity, which indirectly describe the state of the geophysical environment. Despite its high fundamental and practical importance, few publications have been devoted to the analysis of predictive anomalies in induced seismicity. In this paper, the question of the presence or absence of anomalies of the seismic regime before earthquakes in the field of induced seismicity is considered. Studies are being conducted for strong earthquakes in the area of Koina and Varna reservoirs in India. Preliminary preparation of the catalog is carried out, control of the representative magnitude, calculation of spatial maps of seismicity parameters. The results obtained can be used to develop effective measures to reduce risks and ensure the safety of the population, and can also clarify some features of the earthquake preparation process in areas of induced seismicity.
Show AbstractExtreme anisotropy of thermal conductivity of single-walled carbon nanotubes with a scroll-roll structure
Extreme anisotropy of thermal conductivity of single-walled carbon nanotubes with a scroll-roll structure
Yu. P. Zarichnyak$^1$, A. A. Aliverdiev$^2$, E. V. Alekseev$^1$, M. V. Savvateeva$^1$, V. P. Hodunkov$^3$
The methods of the theory of generalized conductivity [1, 2] are used to approximate the effective/equivalent thermal conductivity of defect-free single-walled carbon nanotubes (CNTs) with a scroll-roll structure in the longitudinal and transverse directions relative to the folding axis. Due to the lack of any experimental data and analytical estimates on the longitudinal and transverse thermal conductivity of nanotubes with a scroll-roll structure, the results of an approximate assessment were obtained for the first time, which can be considered predictive. Carbon nanotubes (CNTs) are of considerable interest in a wide variety of fields of science and technology, as they possess a whole range of extreme mechanical, electrical and thermophysical properties [3-4]. A single-layer defect-free carbon nanotube with a scroll-roll structure is shown in Fig. 1a. It is usually represented as a folded sheet of graphene.
Show AbstractModeling of the scanning track formation in the selective laser melting process of 316L steel
Modeling of the scanning track formation in the selective laser melting process of 316L steel
A. A. Gajna$^2$, A. A. Mozhaiko$^1$
Selective laser melting (SLM) is a process that allows to create complex parts with high precision. It involves melting the powder layer by layer using laser radiation to create a solid object. The purpose of this research is to study how different laser parameters affect the size of the melt pool size in the sample. To achieve this goal, the power, scanning speed and diameter of the focal spot of the laser are adjusted. It is reached through numerical modeling and experimental methods. COMSOL Multiphysics model material properties and system behavior. The results of the simulation are graphs of the dependence of the melting zone on the variable parameters. With increasing laser power, the size of the melting zone also increases. As the scanning speed increases, only the length of the zone increases, while the width and depth decrease. Increasing the size of the focal spot first increases the size, but then begins to reduce them. The experimental data obtained because of measuring the dimensions corresponds to the simulation results. This research helps to better understand the SLM process and can be used to optimize processing parameters to achieve desired sample properties.
Show AbstractMathematical methods for analyzing the shape of time series and their applications to remote sensing of the Earth and atmosphere
Mathematical methods for analyzing the shape of time series and their applications to remote sensing of the Earth and atmosphere
A. F. Idrisov
The work is devoted to methods of time series analysis based on the theory of morphological analysis and measuring and computing systems developed at the Department of Mathematical Modeling and Computer Science of the Faculty of Physics of Lomonosov Moscow State University. Modern relevant methods of time series analysis have been studied. A morphological filtering method is proposed to detect a trend in a time series. A computer experiment was conducted on real experimental data (temperature measurements in the city of Tver) using the above method. The results demonstrated the successful identification of the trend component of the time series. It is planned to develop new methods of time series analysis to solve a wider class of problems for a wider class of input data.
Show AbstractUse of an assembly of two thermal conductometric sensors for detection of hydrogen emissions
Use of an assembly of two thermal conductometric sensors for detection of hydrogen emissions
A. E. Elyanov, V. M. Bocharnikov, V. V. Volodin, V. V. Golub, N. K. Dentsel
The work shows the possibility of using an assembly of two thermоconductometric sensors to simultaneously measure the flow speed of a gas mixture and the hydrogen content in it. A measurement concept has been proposed using one sensor located in the flow of the test gas, and a second one closed with a mesh cap, which reduces the dependence of the sensor readings on the flow speed. Test assemblies were manufactured and calibration experiments were carried out in the range of speeds from 0 to 1.84 m/s, hydrogen concentrations from 0 to 100 vol.% and absolute pressure from 0.1 to 5 atm. The results of calibration experiments show that from the signals from two sensors it is possible to unambiguously obtain the flow speed values and hydrogen content in the gas mixture at the location of the sensors. Formulas for converting signals into the required physical quantities are obtained. The assemblies are installed in a test container to study the mixing of hydrogen with air. The response time of the assembly to changes in hydrogen concentration does not exceed 1 s, which allows its use for signaling hydrogen emissions and studying the mixing of hydrogen with air. Graphs of the flow rate and concentration of hydrogen in the mixture versus time are presented.
Show AbstractControl of the spectrum of MeV electrons accelerated in laser plasma of nitrogen clusters
Control of the spectrum of MeV electrons accelerated in laser plasma of nitrogen clusters
A. A. Tausenev$^{1,2}$, P. A. Shcheglov$^1$, M. V. Chashchin$^1$, A. V. Lazarev$^3$, T. A. Semenov$^1$, M. M. Nazarov$^1$
The influence of the sizes of nitrogen clusters on the spectrum of MeV electrons accelerated in a cluster laser plasma under the influence of 5 TW femtosecond laser pulses has been studied. For this task, an electronic magnetic spectrometer was developed and created for the energy ranges: 0.3 – 5 MeV, or 1 – 10.5 MeV. The measured electronic spectra consist of a quasi-monoenergetic peak at 0.4±0.1 MeV, a broad “peak” at 2-3 MeV with an exponential tail with a temperature T = 3±1 MeV. It is shown that the maximum injection of electrons into the accelerating wave is achieved for clusters with an average radius corresponding to the Coulomb explosion limit. The electron bunch was the sum of collimated (10 mrad) and divergent (≈100 mrad) beams with maximum energies up to 10 MeV, which may indicate a hybrid acceleration mode.
Show AbstractTuning lasing characteristics of a longitudinally pumped Nd:YVO$_4$ laser
Tuning lasing characteristics of a longitudinally pumped Nd:YVO$_4$ laser
Yu. A. Sinichkina$^1$, M. V. Gorbunkov$^2$, Yu. Y. Maslova$^2$, M. A. Semenov$^2$
A method for selecting laser media for generation of short laser pulses using the forced Kerr lens with a soft aperture has been developed. It is based on measurements of the tuning lasing characteristics of a solid-state laser with a plane-spherical resonator and a narrow longitudinal pump beam as compared to the size of the fundamental mode of an empty resonator. A scheme is proposed in which the active element is mounted close to a flat mirror. The technique based on the example of the Nd:YVO$_4$ laser made it possible to assign the found resonator configurations to the corresponding irreducible fractions determining the degeneracy conditions 1/6, 1/4, 1/2, 1/5, 1/3, 3/8, 2/7. The dependence of the threshold power on the length of the resonator is obtained under conditions of continuous pumping and with optical shutter with a duty factor 100 over the resonator stability region and near the semi-focal configuration, as well as the output power near the specified configuration. The measurement of the generation threshold with a longitudinal spatial resolution of 0.05 mm was sufficient to determine the boundaries of the region corresponding to the stable generation of short pulses.
Show AbstractTwo-dimensional fractal distributions: theory and practical applications
Two-dimensional fractal distributions: theory and practical applications
F. A. Tulapin, P. V. Korolenko, R. T. Kubanov, O. V. Stepanov, A. I. Terentyeva
A brief retrospective analysis of the properties of fractal light images and their use in medicine is performed. Using algorithms based on the two-dimensional Weierstrass function, the scaling characteristics of regular and stochastic speckle-like fractal structures are calculated. It is shown that scaling of spatial spectra of fractal speckle fields ensures high efficiency of their application in art therapy and ophthalmology. During the modeling of light fields using the Weierstrass function, it was found that their configuration with a certain set of parameters makes it possible to form a multiplex structure of light radiation, which can be successfully used in optical tweezers.
Show AbstractFeatures of Speckle Fractal Structures Propagation in Free Space
Features of Speckle Fractal Structures Propagation in Free Space
R. T. Kubanov, A. M. Zotov, P. V. Korolenko, A. Yu. Mishin
The diffraction transformation of scaling and statistical characteristics of speckle fractal fields is considered. For their model representation, the properties of the two-dimensional Weierstrass function with random phases of its harmonics and the Rayleigh law of intensity distribution are used. The characteristics of the light field at different distances from the initial plane are estimated by the method of its expansion in plane waves in combination with the coating method. It showed that during the propagation of light speckle beams, fractality in the transverse distribution of the field amplitude is preserved, but the values of the fractal dimension can change noticeably. In this case, scaling takes place in the spatial spectrum of radiation. This property ensures high efficiency of using fractal speckle structures in art therapy and ophthalmology.
Show AbstractLaser diode emitters with optical pulse duration less than 10 ns
Laser diode emitters with optical pulse duration less than 10 ns
R. V. Dibolskii$^1$, A. N. Turkin$^1$, A. M. Morozyuk$^2$
Recently, interest in high-power pulsed semiconductor lasers has been growing. This is explained by their high efficiency, as well as wide possibilities of practical application of these light sources, in particular, for data transmission in open space, metrology, machine vision systems (LiDAR), etc. Typically, laser pulse generators include a semiconductor laser and an external source of pulsed pump current. This approach has a number of disadvantages associated with the need to match the semiconductor laser with the pump source, the presence of parasitic connections that appear when generating high-power current pulses, reducing the overall energy efficiency and speed of the system. In addition, the use of external sources does not always allow realizing the advantage of semiconductor lasers associated with small dimensions. The task of implementing pulsed current pumping becomes especially difficult when building systems that include hundreds and thousands of single emitters, both high-power and low-power. Here, in addition to the requirements for the power part of the source, the question arises about the energy efficiency of the generated control signals for such a system. The most promising solution is the use of devices that combine the functions of pulse sources with small-signal control and laser emitters. The integration of a powerful high-speed key with an effective laser heterostructure has made it possible to demonstrate the possibility of generating optical pulses with a duration of less than 10 ns.
Show AbstractСontrolling the spectral characteristics of terahertz radiation by means of multilayer dielectric structures
Сontrolling the spectral characteristics of terahertz radiation by means of multilayer dielectric structures
I. N. Nikolaeva$^{1,2,3}$, G. S. Rogozhnikov$^3$
Experimental research on interaction of mm-wavelength terahertz radiation with multilayer dielectric structures have been carried out. Possibilities of spatial and spectral characteristics control for practical use in secure communication, opaque vision and distant sounding have been shown.
Show AbstractResearch on the Feasibility of Implementing Optical Isolators Based on Distributed Feedback Structures and Their Application in Optical Systems
Research on the Feasibility of Implementing Optical Isolators Based on Distributed Feedback Structures and Their Application in Optical Systems
K. A. Zakharenkov
To implement optical isolators based on diffraction gratings, structures with distributed feedback in the form of waveguides with diffraction gratings, used in DFB lasers, were considered. Bragg conditions, which form the basis for Bragg reflection, were examined, and a constructive comparison of the implementation of optical isolators based on diffraction and Bragg gratings was conducted. As a result, waveguides with embedded diffraction gratings were modeled, and a reflection spectrum graph was constructed. The simulation results demonstrate the potential of using asymmetric diffraction gratings in the development of new types of optical isolators, providing a higher degree of control over light propagation in integrated optical systems where back reflections of the signal can be critical.
Show AbstractHigh-temperature thermal imaging system based on a silicon photodetector
High-temperature thermal imaging system based on a silicon photodetector
A. A. Mantcvetov$^1$, D. S. Barvinenko$^1$, P. O. Lazovskaya$^2$, V. V. Davydov$^2$, V. V. Naumova$^3$
The necessity of searching for new solutions when observing heated bodies in the temperature range of 400°...1400°C is substantiated. The features of the operation and potential characteristics of a thermal imaging measuring system for observing high-temperature objects based on a silicon CMOS sensor have been established. To create a thermal imaging system on a Sony silicon photodetector for observing high-temperature objects, the number of signal electrons formed in the photodetector at different temperatures was calculated. Silicon photodetectors are usually used for observation in the visible range of electromagnetic radiation, where objects reflect the luminous flux. It is proposed to use silicon photodetectors in the near-infrared range, where objects emit. A thermal imaging system based on a silicon photodetector has been developed. The new results obtained using it confirmed the possibility of creating a thermal imaging system based on a silicon photodetector.
Show AbstractDevelopment of OFDM optical signal transceiver based on AWGR
Development of OFDM optical signal transceiver based on AWGR
N. I. Popovskiy, V. V. Davydov
In fiber-optic networks, an increase in the channel speed while maintaining one carrier encounters the problem of a sharp reduction in the transmission distance without regeneration. The need to build additional reinforcement points leads to an increase in the cost of communication systems. The optimal solution to preserve the transmission range and increase the channel speed is the use of multiple carrier frequencies in one combined channel, which is commonly called a superchannel. One of the possible ways to form a superchannel is OFDM. Since the inverse Fourier transform is topologically identical to the Fourier transform, AWGR can be used as an OFDM signal multiplexer in the transmitter. The device of a transceiver is being investigated, which will work as a multiplexer of several input optical channels and a transmitter of one common superchannel into a communication channel.
Show AbstractIdentification and examination of protein compounds utilizing Raman scattering and machine learning techniques
Identification and examination of protein compounds utilizing Raman scattering and machine learning techniques
A. S. Shtumpf
Proteins are important components of the human body, playing a crucial role in the functioning of cells: they catalyze chemical reactions and form cellular structures. An imbalance in protein metabolism can have serious consequences, such as impaired immunity and changes in glandular activity. Detection of various biological compounds is challenging due to their complex intermolecular relationships, and traditional methods such as immunoassays and chromatography may not always provide accurate results. The presented research aims to overcome these limitations by introducing an approach that combines Raman spectroscopy and machine learning to accurately identify protein compounds. This technique aims to minimize errors in quantitative and qualitative analysis and enable systematic investigation of protein compounds.The results obtained during testing of the algorithm on data obtained during experiments indicate the possibility of using this technique for more than 10 analyte substances and achieving an accuracy of over 90%. The methodology for working with experimental data using artificial intelligence tools thus formed can form the basis for creating effective platforms and devices for use not only in the scientific field, but also in the fields of medicine, agriculture, and food safety.
Show AbstractEffect of free charge carriers on dichroism, reflectance and transmittance in anisotropic porous silicon layers
Effect of free charge carriers on dichroism, reflectance and transmittance in anisotropic porous silicon layers
Y. n. Deng, V. Yu. Timoshenko
Theoretical analysis has been conducted to investigate the contribution of free charge carriers to the optical properties in the infrared region of micrometer-thick porous silicon layers composed of anisotropic silicon nanocrystals. Calculations based on a generalized effective medium model, which accounts for the anisotropic shape of silicon nanocrystals and the interaction between the electric field of a light wave and mobile charge carriers in the nanocrystals, indicate a strong dependence of the polarization anisotropy of the reflection, absorption, and transmission coefficients of silicon films on the concentration of free charge carriers. For charge carrier concentrations ranging from 10^16 to 10^20 cm^(-3), significant birefringence and linear dichroism (absorption anisotropy) are observed, along with a non-monotonic dependence of the refractive index, reflection, and transmission coefficients on the concentration of charge carriers. These findings can be applied to develop optical switches and modulators for processing optical signals in silicon photonic elements.
Show AbstractFeatures of controlling the position of the laser radiation axis using controlled electro-optical systems in atmospheric optical communication lines
Features of controlling the position of the laser radiation axis using controlled electro-optical systems in atmospheric optical communication lines
S. A. Shagako$^1$, V. V. Davydov$^{1,2}$, V. V. Naumova$^2$
The prospects for the development and advantages of using atmospheric optical communication lines for solving various tasks are considered. The main problem in these lines is identified, related to the mismatch of the position of the axes of the laser radiation and the photodetector during the transmission of an optical signal, and the possibilities of existing systems for adjusting the trajectory of the axis of laser radiation with passive optical elements are evaluated. The features of the construction of the position of the laser radiation axis using an electro-optical system have been determined and a new automatic adjustment system has been developed. Mathematical relations have been derived for this design of the automatic system, which make it possible to choose its optimal configuration and material for control plates. The functional capabilities of adjusting the position of the laser radiation axis for various design options of an atmospheric optical communication line have been studied.
Show AbstractRobustness of negativity of the Wigner function to dissipation
Robustness of negativity of the Wigner function to dissipation
B. N. Nugmanov
Non-Gaussian quantum states described by negative valued Wigner functions are important both for fundamental tests of quantum physics and for the emerging quantum information technologies. In this paper, we analyze their vulnerability to dissipation. We find the maximal amount of losses at which the negativity disappears and the rate of decrease of the negativity volume around in the vicinity of its zero. We analyze also, how the squeezing affects robustness of the quantum state to losses and show that in some cases the squeezing can improve the robustnes.
Show AbstractUsing Schrödinger cat state for detection of a given phase shift using photon-number resolving detector with finite quantum efficiency
Using Schrödinger cat state for detection of a given phase shift using photon-number resolving detector with finite quantum efficiency
V. L. Gorshenin
One of the standard tasks of interferometry is binary (yes/no) detection of a given phase shift. Its advantage over the task of measuring an unknown phase shift is the availability of a priori information, which allows for higher sensitivity. The use of non-classical non-Gaussian states of the probing light looks very promising in this case. In this work, we consider an interferometric scheme using the Schrödinger cat (SC) non-Gaussian states, taking into account the non-ideal quantum efficiency of the photodetector. We calculate the achievable sensitivity, assuming the realistic values of quantum efficiency and achievable values of the SC state amplitudes.
Show AbstractCombined resistive-capacitive MEMS-switch for advanced communication systems
Combined resistive-capacitive MEMS-switch for advanced communication systems
M. O. Morozov$^{1,2}$, I. V. Uvarov$^2$
The main characteristic of a MEMS switch is the ratio of capacitances in the open and closed states. In conventional switches, this ratio usually does not exceed ten and can be increased several times by using a floating potential electrode. The dependence of the capacitive characteristics, isolation and insertion loss of a switch with the «floating» electrode on the substrate material is investigated.
Show AbstractDevelopment of a digital version of a space debris recognition system based on artificial intelligence
Development of a digital version of a space debris recognition system based on artificial intelligence
A. V. Shavshin$^1$, V. V. Davydov$^1$, D. A. Boldarev$^2$, R. A. Dmitriev$^1$, D. Yu. Klimenko$^2$, A. A. Hudina$^2$
The relevance of developing a space debris recognition system based on artificial intelligence is substantiated. A digital version of a space debris recognition system based on artificial intelligence has been developed, which can serve as the basis for creating a full-fledged system. The development of artificial intelligence code, its training and testing on experimental data was carried out. It has been established that the created digital version of the space debris recognition system based on artificial intelligence has the potential for successful detection and classification of space debris in the orbit of planet Earth.
Show AbstractAC losses in generator elements based on composite HTSC tapes
AC losses in generator elements based on composite HTSC tapes
S. V. Veselova$^{1,2}$, I. V. Martirosyan$^1$, M. A. Osipov$^1$, A. S. Starikovskii$^1$, D. A. Abin$^1$, K. A. Borodako$^1$, D. A. Aleksandrov$^1$, A. Y. Malyavina$^1$, A. N. Moroz$^{1,2}$, S. V. Pokrovskii$^{1,2}$
To estimate AC losses, simulations were carried out with different frequencies (from 50 Hz to 1033 Hz) and transport current amplitude from 10% to 90% of the critical current density Jc. During the study, calculated data were obtained allowing us to conclude that the losses of closed-circuit HTSC windings are higher than the losses on racetrack coils.
Show AbstractInvestigation of inductively coupled plasma parameters during the etching of a polysilicon gate
Investigation of inductively coupled plasma parameters during the etching of a polysilicon gate
F. V. Oksanichenko
A self-consistent 0-dimensional plasma model of the $Cl_2/Ar$ mixture is proposed under conditions typical for plasma chemical etching of a polysilicon gate. The model is based on the joint solution of the equations of chemical kinetics, plasma quasi-neutrality and power balance for steady-state plasma conditions. The solution was carried out by iteration method. The model took into account 3 types of neutral particles (Cl2, Ar, radical Cl) and 4 types of ions (Cl+, Cl2+, Ar+, Cl-). The initial composition of the mixture, the input power and the gas pressure were used as input parameters. Calculated data on the effect of the initial composition of the mixture on the physical parameters of the plasma and the concentration of active particles were obtained. The results are qualitatively consistent with the literature data.
Show AbstractEffect of partial unitarity requirements on the accuracy of measurements of Wilson coefficients in the processes of three and four top quarks production
Effect of partial unitarity requirements on the accuracy of measurements of Wilson coefficients in the processes of three and four top quarks production
A. M. Aleshko, E. E. Boos, V. E. Bunichev, L. V. Dudko
The problem of violation of unitarity in the Effective Field Theory of Standard Model (SMEFT) when applied to the processes of three and four top quarks production for relevant efficient operators. Using the optical theorem, boundaries of areas corresponding to the condition of non-violation of partial unitarity were determined. It was shown, how these restrictions affect the accuracy of setting limits on the corresponding Wilson coefficients. It has been established that for the processes under study, the influence of unitary restrictions is noticeable and leads to a deterioration in the accuracy of setting the corresponding limits even at collision energies of 13 and 14 TeV.
Show AbstractAbout spin connections as quantization variables of gravity
About spin connections as quantization variables of gravity
A. B. Arbuzov, A. Nikitenko
Quantization of conformal general relativity is studied. The components of spin connectivity are considered to be the basic variables of quantum gravity. Their properties are analyzed and the dynamic part is highlighted. The work also uses tetrad formalism and the Arnovitt-Deser-Misner formalism. The gravitational action turns out to be quadratic in the components of the spin connection. Secondary quantization of the gravitational field is performed in terms of spin connectivity and further prospects for this approach are discussed.
Show AbstractRare decays of $D_s$ mesons into light pseudoscalar mesons
Rare decays of $D_s$ mesons into light pseudoscalar mesons
V. O. Galkin$^1$, I. S. Sukhanov$^{1,2}$
Rare decays of $D_s$ mesons into pseudoscalar mesons are studied in detail within the framework of the relativistic quark model based on the quasipotential approach and quantum chromodynamics. The form factors that parameterize the matrix elements of the weak current between meson states are calculated with consistent account of relativistic effects. Their dependence on the square of the transferred momentum is explicitly defined in the whole accessible kinematic region. The effects of electroweak physics at short distances and the contributions of intermediate resonances at large distances are taken into account using effective Wilson coefficients,. In the framework of the helicity formalism, differential decay rates and branching fraction are calculated. The obtained results are consistent with the existing upper experimental limits.
Show AbstractMultimodal EAS events with energies $10^{16} − 5\times10^{18}$~eV according to Corsika data at the level of the Tien Shan station (3346m)
Multimodal EAS events with energies $10^{16} − 5\times10^{18}$~eV according to Corsika data at the level of the Tien Shan station (3346m)
M. A. Samoilov$^{1,2,3}$, A. M. Anokhina$^{1,2}$
In various experiments where Extensive Atmospheric Showers (EAS) are recorded, EASs with an unusual, “multimodal” temporal structure are observed - several pulses separated in time by several hundred ns are recorded at the installation detector modulars. In this work, the task was to demonstrate the possibility of multimodal events at the detector points of the Horizon-T installation, located at the Tien Shan high-mountain station of the Lebedev Physical Institute at an altitude of 3346 m above sea level without the involvement of exotic particles and processes. Simulation based on the commonly used Corsika code with nuclear interaction model QGSJET. It was assumed that several particles or groups of particles from one EAS, separated by a significant time, enter the detector’s time gate, which leads to the formation of a sequence of several pulses. This hypothesis was successfully confirmed by modeling ultra-high energy EASs from $10^{16} − 5\times10^{18}$~eV close to vertical (up to 30 deg) and highly inclined (from 30 up to 70 deg).
Show AbstractOn fluctuations of energy release in the substance of passing detectors
On fluctuations of energy release in the substance of passing detectors
A. M. Azhakin$^1$, I. A. Kudryashov$^2$
The influence of the transverse segmentation of the silicon semiconductor detector system and the distance between the layers in the system on the fluctuation of the total energy deposition in the detector material during the passage of relativistic nuclei through it has been considered using modeling in the Geant4 software package. The modeling has shown that for relativistic nuclei, the energy depositions in the detectors of the series are not statistically independent, and the fluctuations of the total energy deposition significantly depend on the distance between the layers of the system. Thus, a significant influence of energetic delta electrons, formed during the interaction of the nucleus with the passage medium, on the total energy deposition, and mainly on its fluctuations, has been demonstrated.
Show AbstractThe formation of radioactive isotopes during space flights using low-thrust engines
The formation of radioactive isotopes during space flights using low-thrust engines
K. R. Rakhimchanova$^1$, A. N. Turundaevskiy$^2$
Currently, the development of spacecraft with low-thrust electric propulsion systems is underway. These systems have several advantages over traditional rocket systems, such as the ability to deliver larger payload to the Moon at a lower cost. However, flight times are significantly longer (300 days or more), leading to prolonged (compared to the Hohmann transfer orbit) exposure of the payload to radiation belts particles, galactic and solar cosmic rays. During the interaction of high-energy protons and nuclei with the nuclei of the payload material, fragmentation and formation of radioactive isotopes are possible. In the case of creating habitable stations on the lunar surface or in lunar orbit, a significant part of the payload will consist of food products. The question then arises as to whether cosmic radiation will lead to accumulation of dangerous amounts of radioactive isotope in these products that could be harmful to life. In this work, the interaction of cosmic ray proton fluxes along the trajectory of a spacecraft with low-thrust engines with target material (meat has been chosen as the target) has been simulated. As a result, it has been found that the level of induced radioactivity based on a comparison with maximum permissible limits of radionuclides in food products is insignificant. This result is important for future lunar exploration.
Show AbstractAnalysis of the angular distributions of the direct Cherenkov light by the SPHERE-3 detector
Analysis of the angular distributions of the direct Cherenkov light by the SPHERE-3 detector
N. O. Ovcharenko, V. I. Galkin
In the present article we study the capability of a detector of the direct Cherenkov light intended for the future SPHERE-3 detector which is to separate the extensive air shower by the primary particle mass. For the purpose we analyze the angular distributions of light in detector and reveal the differences of their shapes for hydrogen, nitrogen and iron nuclei. Distribution shape are threated a few ways: with the use of threshold values and by approximating them with normal distribution. The lentgh of the distribution long axis is used as a parameter for the mass separation. We compare the efficiency of the parameter for the methods considered as well as for the integral and local criteria for different grid pitches of the angular distribution. In the conclusion we discuss the future plans to improve the approximation and to search for the other sensitive mass parameters.
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