Moscow University Physics Bulletin最新文献

{"title":"Singularities of Diffuse Wave Fields in Scattering Media with Refractive Index Gradients","authors":"Ya. A. Ilyushin","doi":"10.3103/S0027134924700450","DOIUrl":"10.3103/S0027134924700450","url":null,"abstract":"<p>The subject of this paper is the radiative transfer in media with refractive index gradients. Asymptotic expressions of the intensity distributions in the vicinity of singular directions are derived. Critical conditions for the occurrence of singular intensity distributions in fields of scattered radiation in a medium are formulated. It is shown that singular radiation fields in such media can be generated, among other things, by nonsingular configurations of radiation sources. The obtained results are verified by direct comparison with the results of numerical calculations using the Monte Carlo statistical modelling method.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 3","pages":"336 - 344"},"PeriodicalIF":0.4,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Hydrophobic Dust Particles on the Evaporation Rate from Water Surface","authors":"I. N. Ivanova,&nbsp;O. N. Melnikova","doi":"10.3103/S0027134924700516","DOIUrl":"10.3103/S0027134924700516","url":null,"abstract":"<p>In the paper, the effect of natural dust deposited from the air on the evaporation rate from the water surface is experimentally investigated. Experiments were conducted for stationary liquid without wind blowing across the surface and with mild wind that does not deform the surface, at a constant rate of particle deposition. It is shown that the evaporation rate is a linear function of the difference in the saturated vapor pressure at the water surface and the partial pressure of the air mixture at the temperature and relative humidity in the laboratory at the beginning of the deposition process, when the proportion of the surface covered with dust is small. With the increase in deposition time, hydrophobic particles gather into conglomerates, reducing the proportion of the exposed surface and the evaporation rate.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 3","pages":"408 - 414"},"PeriodicalIF":0.4,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Cluster Ion Bombardment on the Roughly Polished Surface of Single-Crystal Germanium Wafers","authors":"I. V. Nikolaev,&nbsp;N. G. Korobeishchikov,&nbsp;A. V. Lapega","doi":"10.3103/S0027134924700462","DOIUrl":"10.3103/S0027134924700462","url":null,"abstract":"<p>The surface treatment of single-crystal germanium with an argon cluster ion beam has been investigated. The original surface of the germanium wafers was bombarded with argon cluster ions with high (105 eV/atom) and low (10 eV/atom) specific energies. Using an atomic force microscope, images were obtained and a comparison of the surface topography before and after cluster ion bombardment was conducted. The smoothing of the surface was demonstrated using the power spectral density function of roughness in the range of spatial frequencies: 1) <span>(nu=1{-}8)</span>\u0000 <span>(mu)</span>m<span>({}^{-1})</span>—for the high-energy mode; 2) <span>(nu=0.7{-}2.5)</span>\u0000 <span>(mu)</span>m<span>({}^{-1})</span>—for the low-energy mode.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 3","pages":"330 - 335"},"PeriodicalIF":0.4,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tsunami Waves off the Southeastern Coast of Sakhalin Island Caused by the Eruption of the Hunga–Tonga–Hunga–Ha’apai Volcano on January 15, 2022 According to Observations by Bottom Devices of Waves","authors":"D. P. Kovalev,&nbsp;P. D. Kovalev","doi":"10.3103/S0027134924700449","DOIUrl":"10.3103/S0027134924700449","url":null,"abstract":"<p>The observation of waves (sea level oscillations) in the coastal water area of the southeastern coast of Sakhalin Island was carried out from November 2021 to May 2022 using bottom-mounted high-precision ARW 14 K devices with one second discreteness. The analysis of the obtained time series revealed the presence of anomalous waves in the range of tsunami waves in January 2022. It is shown that the waves detected on January 15, 2022 with periods of 15 min–4 h, significantly standing out above the background, are associated with volcanic tsunami waves. Spectral analysis of the time series showed that the maximum in the spectra of sea level oscillations found after the volcanic eruption is close to the period of the first mode of the shelf seiche. This indicates that incoming tsunami waves excite shelf seiches in the coastal zone and contribute to the generation of longshore and transverse seiches into Mordvinov Bay. Time series analysis made it possible to establish that the spectral density of sea level oscillations for the time interval of the beginning of the eruption of the Hunga–Tonga–Hunga–Ha’apai volcano from December 21, 2021 to January 11, 2022 significantly differs from the spectral density for the time of the Plinian volcanic eruption. An analysis of the statistical characteristics of sea level oscillations performed on two-day series in the range of periods 1 min–4 h for background waves and tsunamis showed an increase in the rms by 3.5 times for a time series containing tsunami waves. It has been established that for background time series containing tsunami waves, the coefficients of asymmetry and kurtosis differ little from ‘‘Gaussia’’ values. This indicates that the arrival of tsunami waves from distant sources does not significantly disrupt the stationarity of the wave field in the observation area.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 3","pages":"399 - 407"},"PeriodicalIF":0.4,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dependence of Temperature Conditions of Planetary Atmospheres in the Solar System on the Length of the Annual Cycle","authors":"I. I. Mokhov","doi":"10.3103/S0027134924700528","DOIUrl":"10.3103/S0027134924700528","url":null,"abstract":"<p>The results of a comparative analysis of various characteristics of the temperature conditions of the planetary atmospheres in the Solar System and their dependence on orbital parameters, in particular on the length and angular frequency of the annual cycle, are presented. A root dependence on the angular frequency of the dry adiabatic lapse rate is noted. The dependence of the planetary equilibrium temperature in the form of the cubic root of the angular frequency of the annual cycle is related to Kepler’s third law. For Venus, Earth, Mars, Jupiter, and Saturn, the root dependence of the scale height and the troposphere height on the annual cycle length is manifested, and the atmospheric features of the most distant planets from the Sun—Uranus and Neptune—are noted.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 3","pages":"393 - 398"},"PeriodicalIF":0.4,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electric Dipole Polarizability of Magic Nuclei","authors":"N. N. Arsenyev,&nbsp;A. P. Severyukhin","doi":"10.3103/S0027134924700322","DOIUrl":"10.3103/S0027134924700322","url":null,"abstract":"<p>Using the examples of magic nuclei <span>({}^{40,48})</span>Ca, <span>({}^{68,78})</span>Ni, <span>({}^{132})</span>Sn, and <span>({}^{208})</span>Pb, the correlation between electric dipole polarizability and the thickness of the neutron ‘‘skin’’ has been studied. The distribution of <span>(E1)</span>-transition strength was calculated within the random phase approximation using the Skyrme energy density functional. Comparison with experimental data made it possible to constrain the value of nuclear symmetry energy within the range <span>(J=30{-}37)</span> MeV.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"200 - 207"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Monte Carlo Simulation Study of the Optimal Source Offset for Scatter Fraction Estimation in PET and the Influence of the Scanner and Object Characteristics","authors":"Mahmoud El Katib,&nbsp;El Mahjoub Chakir,&nbsp;Rajaa Sebihi,&nbsp;Hind Saikouk","doi":"10.3103/S0027134924700383","DOIUrl":"10.3103/S0027134924700383","url":null,"abstract":"<p>In positron emission tomography (PET), the scattered photons represent a major image degrading factor. The scatter fraction (SF) of PET scanners is experimentally determined following the National Electrical Manufacturers Association (NEMA) NU 2 protocol, using a polyethylene phantom with a line source inserted at 45 mm radial offset from the phantom’s center. In this work, we aim to investigate the optimal radial offset of the line source, that represents the SF of a uniformly activated phantom, for the lutetium yttrium orthosilicate (LYSO)-based uEXPLORER total body PET scanner. Additionally, we propose to study the impact of several factors (axial field-of-view (AFOV), crystal material and heterogeneities) on this optimal offset, in an effort to provide recommendations for a wide range of PET scanner configurations. We performed Monte Carlo (MC) simulations of the uEXPLORER scanner along with five phantoms of different diameters, using the Geant4 Application for Tomographic Emission (GATE) code. We performed supplemental MC simulations in which we varied the crystal material, the AFOV and we introduced bone and lung heterogeneities in the phantoms to assess their impact on the optimal offset findings. Our results demonstrated that the 45 mm offset overestimates the SF of the uniform 20 cm diameter phantom by 24.3<span>(%)</span>. Instead, an offset of 87 mm was reproducing this SF. For the phantoms having diameters in the range of 10–50 cm, an offset of 90.7<span>(%)</span> of the phantom’s radius was shown to be optimal (best fit). No AFOV-related impact has been observed on this optimal offset. The influence of the heterogeneities was also small with less than 1.1<span>(%)</span> absolute deviation in the SF. This offset could then be used for all AFOV lengths PET scanners using LYSO crystal. The impact of the crystal material was shown to be minimal and an offset of 91.5<span>(%)</span> of the phantom’s radius is consequently recommended as an average for other PET scanners.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"267 - 274"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A New Microscopic Representation of Spin Dynamics in Quantum Systems with Biquadratic Exchange Interactions","authors":"M. I. Trukhanova,&nbsp;P. Andreev","doi":"10.3103/S0027134924700255","DOIUrl":"10.3103/S0027134924700255","url":null,"abstract":"<p>There is a version of the Landau–Lifshitz equation that takes into account the Coulomb exchange interactions between atoms, expressed by the term <span>({sim}mathbf{s}timestrianglemathbf{s})</span>. On the other hand, ions in magnetic materials have several valence electrons on the <span>(d)</span>-shell, and, therefore, the Hamiltonian of many-electron atoms with spins <span>(S&gt;1)</span> should include a biquadratic exchange interaction. We propose a novel fundamental microscopic derivation of the spin density evolution equation with an explicit form of biquadratic exchange interaction using the method of many-particle quantum hydrodynamics. The equation for the spin density evolution is obtained from the many-particle Schrödinger–Pauli equation and contains the contributions of the usual Coulomb exchange interaction and the biquadratic exchange. Furthermore, the derived biquadratic exchange torque in the spin density evolution equation is proportional to the nematic tensor for the medium of atoms with spin <span>(S=1)</span>. Our method may be very attractive for further studies of the magnetoelectric effect in multiferroics.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"232 - 238"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calculation of the Effective Mass of Electrons and Holes of the TlGaTe({}_{mathbf{2}}) Compound","authors":"A. P. Abdullaev,&nbsp;D. M. Gafarova","doi":"10.3103/S0027134924700346","DOIUrl":"10.3103/S0027134924700346","url":null,"abstract":"<p>Based on the band structure of TlGaTe<span>({}_{2})</span> compound, the extrema of the valence and conduction bands were determined and the tensor of the components of the inverse effective mass of electrons and holes was calculated.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"264 - 266"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of the April 27, 2012 Flare Emission in the Spectral Lines of Hydrogen, Helium, and Calcium","authors":"Yu. A. Kupryakov,&nbsp;K. V. Bychkov,&nbsp;O. M. Belova,&nbsp;V. A. Maliutin,&nbsp;A. B. Gorshkov","doi":"10.3103/S0027134924700334","DOIUrl":"10.3103/S0027134924700334","url":null,"abstract":"<p>The paper presents the results of the analysis of the sloar flare SOL2012-04-27 emission in hydrogen, helium, and calcium spectral lines observed on the horizontal solar facility HSFA-2 of the Ondřejov Observatory (Astronomical Institute of the Czech Academy of Sciences). After processing the spectra, the integrated emission fluxes in the lines were determined. The data collected are treated using the approach of rapid energy release inside the chromosphere, accompanied by gas evaporation. Within the framework of the heated gas model, a theoretical calculation of the plasma parameters was performed, taking into account the physical conditions in the chromosphere, including spectral line self-absorption. Comparison across six lines allowed, with a high degree of validity, the reconstruction of the temperature <span>(T)</span>, density, and spatial structure of the emitting gas. The best agreement of theory with observations is obtained in the model of the spread of inhomogeneous clouds, each of which has hot (<span>(Tapprox 18,000{-}19,500)</span> K) and less heated (<span>(Tapprox 8000{-}9000)</span> K) regions. On average, one cloud contributes about ten percent to the total emission flux.</p>","PeriodicalId":711,"journal":{"name":"Moscow University Physics Bulletin","volume":"79 2","pages":"275 - 282"},"PeriodicalIF":0.4,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}