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Issue 2, 2024

Theoretical and mathematical physics

Decoherence of neutrino oscillations in a magnetic field due to wave packets separation

Decoherence of neutrino oscillations in a magnetic field due to wave packets separation

A. R. Popov$^1$, A. I. Studenikin$^2$

Memoirs of the Faculty of Physics 2024. N 2.

Neutrino oscillations in a magnetic field considered within the formalism of wave packets. Damping of neutrino oscillations in a magnetic field due to neutrino wave packets separation is studied. The expressions for neutrino oscillations probabilities in a magnetic field accounting for decoherence effects are obtained. It is shown that the coherence lengths of oscillations on magnetic frequencies are proportional to the cube of neutrino energy. The obtained results are of interest for neutrino telescopes IceCube, Baikal-GVD and KM3NeT, and also can be applied for description of supernovae neutrino oscillations effects would be detected by JUNO, Hyper-Kamiokande and DUNE.

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Radiophysics, electronics, acoustics

Special Properties of Wideband Communication Based on Generators with Rough Dynamics

Special Properties of Wideband Communication Based on Generators with Rough Dynamics

D. O. Lubchenko$^{1,2}$, O. B. Isaeva$^{1,3}$

Memoirs of the Faculty of Physics 2024. N 2.

The article compares the efficiency of the information transmission based on the synchronization of different wideband signal generators, both in the presence of noise in the communication channel and in the conditions of frequency distortion of the signal transmitted in the communication channel. The generators of a hyperbolic chaos and a strange nonchaotic attractor, which are used in this work as generators of a signal, demonstrate complex dynamics and have a wide continuous spectrum. It was shown that the communication method based on a hyperbolic chaos is more sensitive to noise than on the generator of a strange nonchaotic attractor. The presence of a stopban in the low-frequency and high-frequency regions, however, makes it possible to detect the information with minimal distortion using communication circuits based on both generators.

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The development of a voltage-controlled generator with digital tuning for a multifunctional radar station

The development of a voltage-controlled generator with digital tuning for a multifunctional radar station

D. A. Ryzhova, V. B. Fadeenko

Memoirs of the Faculty of Physics 2024. N 2.

The necessity of multifunctional radar station development for solving various tasks, including environmental monitoring, is substantiated. The necessity has been established for solving several tasks, including environmental monitoring of air spaces, scanning the emitted microwave signal frequency in the range from 2 to 18 GHz, with a tuning step of 10 MHz. The emerging radar station problems during the implementation of this range are considered. The disadvantages of analog voltage-controlled generators (VCG), which are used in radar stations to synthesize a grid of microwave frequencies in the range of several GHz, are considered. A digital tuning VCG design has been developed on the domestic component base to implement the synthesis of a microwave frequency grid in the range from 2 to 18 GHz. The main characteristics of the developed VCG are investigated and compared with similar developments of the world's leading manufacturer (Planar Monolithics Industries). The effectiveness of radar station with a developed VCG usage for solving various tasks is shown.

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Condensed matter physics

Investigation of the structure and phase composition of Cu-Si films obtained by ion beam sputtering

Investigation of the structure and phase composition of Cu-Si films obtained by ion beam sputtering

E. S. Kersnovsky, I. V. Polshin, K. A. Barkov, D. N. Nesterov, S. A. Ivkov, V. A. Terekhov, B. L. Agapov, A. V. Sitnikov

Memoirs of the Faculty of Physics 2024. N 2.

In this work, the structure, phase composition and electronic structure of Cu-Si films with different copper content (from 15 to 68 wt.%) obtained by ion beam sputtering were studied by X-ray diffraction and ultra-soft X-ray emission spectroscopy. It was found that when Cu-Si films have a low copper content (~15 wt.%), the phases of 𝝲-Cu5Si and amorphous silicon a-Si are formed. Increasing the Cu content to up to 68 wt.% leads to the formation of the phases 𝞰-Cu3Si and 𝞰''-Cu3Si, as well as partial oxidation of copper with the formation of Cu2O oxide, while significant changes in the electronic structure of the valence band are observed as a result of the interaction of copper d-electrons and silicon s,p-electrons. An increase in the copper content in the composition of Cu-Si films from ~15 wt.% to ~68 wt.% is accompanied by a decrease in resistivity from ~1*10-3 to ~3*10-4 ohms *cm.

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Teaching methods

Research works with schoolchildren using the example of studying the solar wind

Research works with schoolchildren using the example of studying the solar wind

S. B. Ryzhikov$^1$, Yu. V. Ryzhikova$^2$

Memoirs of the Faculty of Physics 2024. N 2.

The methodology for gradually involving schoolchildren in research activities from choosing a topic to conducting a computational experiment, analyzing the results and their further publication is considered. It is proposed to use the Euler scheme with modification to increase the accuracy of calculations. It is proposed to use modeling of the movement of charged particles in the Earth's magnetic field as a research direction. To simplify calculations, the Earth's field was considered a dipole. Coulomb interaction and particle radiation were neglected. Experience shows that schoolchildren master simple numerical methods very well. They can calculate particle trajectories, analyze them, and understand that particles can only reach the Earth's surface near the poles. The stages of the study are selected so that schoolchildren can gain useful knowledge and skills, even if they do not have the patience to complete the work.

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