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Electron Beam Spectrum of After Passing Through Aluminum Plates

Electron Beam Spectrum of After Passing Through Aluminum Plates

U. A. Bliznyuk$^{1,2}$, P. U. Borshchegovskaya$^{1,2}$, S. A. Zolotov$^1$, V. S. Ipatova$^2$, G. A. Krusanov$^3$, A. D. Nikitchenko$^1$, F. R. Studenikin$^{1,2}$, A. P. Chernyaev$^{1,2}$

Moscow University Physics Bulletin 2022. N 4.

This study presents analytical dependences describe the electron beam spectrum and the dose distribution over the depth of an object when it is irradiated with an accelerated electron beam with an initial energy of 1 to 10 MeV after passing through aluminum plates with a thickness of 1 mm to 5 mm. The developed mathematical model allow to reconstruct the electron beam spectrum after passing through the plates with an error of no more than 10% and the dose depth distributions with an error of no more than 5%.

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Effect of thermoradiation treatment on structure of potassium-alumoborate glasses with iron oxides additives

Effect of thermoradiation treatment on structure of potassium-alumoborate glasses with iron oxides additives

E. M. Ibragimova$^1$, M. K. Salakhitdinova$^2$

Moscow University Physics Bulletin 2022. N 4.

The paper presents the results of structural studies of glasses of the composition K2ОAl2O3B2O3 with 0.1 to 3.0 wt % Fe2O3 additives, subjected to thermoradiation treatment at irradiation temperatures of samples 423, 473, 523, and 573 K inside the gamma field 60C at dose rate of 236 R/s. X-ray diffraction spectra revealed the crystal structure of nanoscale inclusions of iron oxides phases of magnetite and hematite in the grid glass. SEM showed that gamma irradiation with doses of (0.3-1.0) 106 R reduces the initial surface roughness from 0.5 to 0.1, and thermoradiation treatment polishes the surface to high degree.

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Hartree--Fock approach to dynamical mass generation in (2+1)-dimensional Thirring model

Hartree--Fock approach to dynamical mass generation in (2+1)-dimensional Thirring model

M. M. Gubaeva$^1$, R. N. Zhokhov$^2$, K. G. Klimenko$^{1,3}$, T. G. Khunjua$^4$

Moscow University Physics Bulletin 2022. N 4.

(2+1)-dimensional Thirring model with 4-component fermions is investigated in the framework of the Hartree-Fock approach. It is shown that its ground state is in fact a mixed phase composed of a phase in which mass of fermions is dynamically generated and chiral invariance is violated spontaneously, as well as a phase in which a $\cP$-odd mass arises dynamically. It was found that dynamic mass generation is possible for any finite number of Fermi-fields.

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Magnetocaloric effect in GdMn1-xTxSi (T = Ti, Fe, Co) compounds

Magnetocaloric effect in GdMn1-xTxSi (T = Ti, Fe, Co) compounds

S. A. Nikitin, I. A. Ovchenkova, M. E. Blinova, I. S. Tereshina

Moscow University Physics Bulletin 2022. N 4.

The direct measurements of the magnetocaloric effect (MCE) and calculations of the change in the magnetic entropy of a large group of GdMn1-xTxSi (T = Ti, Fe, Co) compounds with a CeFeSi type structure were carried out. All studied compounds are ordered ferro- or ferrimagnetically in a wide temperature range from 120 K to 390 K. The maximum value of the MCE (DTad = 1.1 K when the external magnetic field changes from 0 to 12 kOe) is observed for the GdFeSi compound. The obtained concentration dependences of the Curie temperatures and MCE values ​​are analyzed under the assumption that the magnetism of the 3d sublattice has a itinerant nature.

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The exact analytical solution, based on methods of coupled wave thicknesses and equivalent substitution, for multilayer periodic structures with specified amplitude-phase characteristics. synthesis (π structures)

The exact analytical solution, based on methods of coupled wave thicknesses and equivalent substitution, for multilayer periodic structures with specified amplitude-phase characteristics. synthesis (π structures)

A. E. Zhitelev, A. V. Kozar

Moscow University Physics Bulletin 2022. N 4.

The development of methods for the analysis and synthesis of multilayer periodic structures with specified characteristics is an urgent problem for solving a number of problems in both applied and fundamental physics. Based on the method of coupled wave thicknesses and the algorithm built on its basis, exact analytical relationships were found, including the entire set of structural solutions and allowing the synthesis of multilayer structures with given amplitude-phase characteristics, for any values ​​of the refractive indices, both of the media being matched and the materials of the layers.

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Optimization of the Low-Intensity Beam Extraction Mode at the Medical Synchrotron for Application in Proton Radiography and Tomography

Optimization of the Low-Intensity Beam Extraction Mode at the Medical Synchrotron for Application in Proton Radiography and Tomography

A. A. Pryanichnikov$^{1,2}$, A. P. Chernyaev$^2$, M. A. Belikhin$^{1,2}$, P. B. Zhogolev$^1$, A. E. Shemyakov$^1$, I. N. Zavestovskaya$^1$

Moscow University Physics Bulletin 2022. N 4.

Proton therapy is one of the rapidly developing types of radiation therapy for oncological diseases. The use of proton imaging, method in which the relative stopping power for protons is reconstructed directly, can significantly increase the accuracy and effectiveness of proton therapy. This paper demonstrates the results of experimental work that was work carried out at the synchrotron of proton therapy complex Prometheus. The optimization of the synchrotron operating mode with low-intensity beam extraction was done for proton radiography and tomography purposes. Data about key changes of the beam extraction parameters for low particles flux as well as low intensity beam control methods was descried.

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Temperature-dependent sputtering with gas cluster ions. Computer simulation

Temperature-dependent sputtering with gas cluster ions. Computer simulation

A. E. Ieshkin$^1$, A. D. Zavilgelsky$^{1,2}$, M. E. Beliaev$^1$, A. V. Nazarov$^2$

Moscow University Physics Bulletin 2022. N 4.

The temperature dependences of copper sputtering yields by argon cluster ions in the temperature range from 300 K to 1100 K (0.8 of the melting point) were studied by computer simulation using molecular dynamics technique. Argon clusters with a fixed energy of 10 keV had sizes from 50 to 500 atoms. It has been found that as the cluster size increases, i.e., as the specific energy of its atoms decreases, the dependence of the sputtering yield on temperature becomes more pronounced. The results are compared with the thermal spike model.

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Ferromagnetic resonance investigations of exchange biased NiFe/IrMn/NiFe trilayer structures

Ferromagnetic resonance investigations of exchange biased NiFe/IrMn/NiFe trilayer structures

I. O. Dzhun, G. V. Babaytsev, A. V. Makunin, I. L. Romashkina, M. G. Kozin, C. N. Gavrilovich

Moscow University Physics Bulletin 2022. N 4.

Trilayer thin-film magnetic structures NiFe/IrMn/NiFe obtained by DC magnetron sputtering in the presence of a constant magnetic field 420 Oe were investigated by ferromagnetic resonance (FMR) technique. The dependences of the exchange bias, misalignment angle between the uniaxial and unidirectional anisotropies, and the FMR linewidth on the thickness of the antiferromagnetic IrMn layer in the range from 2 to 50 nm are compared for samples with hard Ni40Fe60 and soft Ni75Fe25 ferromagnetic layers of the same 10 nm thickness. Using the data of other authors and our previous data for bilayer structures, possible reasons of the observed dependences are discussed.

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Synthesis of polymer composites reinforced with carbon nanotubes and study of their charging under an electron beam

Synthesis of polymer composites reinforced with carbon nanotubes and study of their charging under an electron beam

E. A. Vorobyeva$^{1,3}$, D. O. Peshnina$^{1,2}$, A. A. Tatarintsev$^{1,2}$, A. P. Evseev$^{1,2}$, A. A. Shemukhin$^{1,2}$

Moscow University Physics Bulletin 2022. N 4.

Multiwalled carbon nanotubes were obtained by pyrolytic vapor deposition and composites with epoxy resin were synthesized. The Raman spectra show characteristic carbon nanotube peaks on epoxy resin composite samples. The charge characteristics of the obtained samples were studied using an electron probe measuring complex. In samples of composites based on aligned nanotubes with epoxy resin, charging under an electron beam was observed to a much lesser extent. The data obtained demonstrate the possibility of using a polymer composite with oriented nanotubes as an antidynatron coating.

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Analysis of the spatial dispersion effect on the absorption of electromagnetic energy by magnetoplasmonic nanoparticles

Analysis of the spatial dispersion effect on the absorption of electromagnetic energy by magnetoplasmonic nanoparticles

Yu. A. Eremin$^1$, A. S. Penzar$^2$

Moscow University Physics Bulletin 2022. N 4.

In this paper, the diffraction problem of a plane electromagnetic wave on an infinite layered magnetoplasmonic nanocylinder is considered. The resulting effects of spatial dispersion in the golden shell, also known as the nonlocality effects, are taken into account within the framework of the Generalize Nonlocal Optical Response theory. Based on the new scheme of the discrete source method, the influence of particle deformation and the effects of spatial dispersion on the position and amplitude of the maximum energy absorption is analyzed. It is shown that the maximum position can be shifted to the transparency region of human biological tissues due to variations in the thickness of the golden shell and material of the core. It is established that account for the spatial dispersion in the metal shell leads to a decrease in the absorption intensity and a shift of the maximum position to the short-wave region.

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