Bulletin of the Lebedev Physics Institute最新文献

We study the effect of technological parameters on the characteristics of the Fano resonance in semiconductor structures formed on silicon single-crystal substrates using thermal diffusion of boron. The Fano resonance is investigated using Raman spectroscopy. It is shown that the formation of porous silicon films on the surface of a single-crystal substrate expands the possibilities of fabricating structures with specified Fano resonance parameters, compared to samples without a porous film.

The paper describes the search results for CP violation in the D⁰ → (K_{S}^{0}K_{S}^{0}) decay. The analysis was performed using the proton–proton collision data with centre-of-mass energy of (sqrt s ) = 13 TeV, recorded by the CMS experiment at the Large Hadron Collider. The analyzed data sample contains about 10¹⁰ events associated with production of charm hadrons, which allows performing precise measurements. The measured CP violation parameter is A_CP (D⁰ → (K_{S}^{0}K_{S}^{0})) = (6.2 ± 3.1 (stat.) ± 0.2 (syst.) ± 0.8 (A_CP (D⁰ → (K_{S}^{0})π⁺π⁻))%, where the last uncertainty is due to the uncertainty in the reference channel asymmetry A_CP (D⁰ → (K_{S}^{0})π⁺π⁻). The obtained results are consistent with no CP violation in the studied decay. This analysis is the first measurement of CP violation in charm sector at the CMS experiment.

We report an experimental study of self-assembly processes that occur during the evaporation of a colloidal solution of nanostructured carbon in ethanol during vertical deposition of nanoparticles on a quartz substrate. The effect of the pulling speed and the angle at which the substrate is fixed on the structure of the carbon coatings formed on the surface of the samples is discussed. The fabricated nanocarbon films are analyzed in detail. Optimal conditions for the formation of the most uniform spatial distribution of nanoparticles and their agglomerates over the surface of quartz substrates are determined.

Transmission electron microscopy is used to study the formation of InGaAs/GaAs quantum dots by molecular beam epitaxy under the influence of a Bi vapor flow on the growth surface at different temperatures of the GaAs substrate. Mixed-dimensional nanostructures (0D/2D) are found. Energy-dispersive X-ray spectroscopy demonstrates that Bi acts as a surfactant and is not trapped by the growing layers.

We report on a new method for producing amorphous silicon in which a Fano resonance is observed. The method involves treating a porous silicon film doped with boron with pulsed laser radiation. The results of studying the fabricated amorphous silicon films using Raman spectroscopy are presented.

Dynamic photohyperthermia is a method based on synchronization of a moving fluid flow and a laser beam. In this paper, the method is simulated and experimentally tested for a flow of an aqueous suspension of titanium nitride (TiN) nanoparticles (NPs) irradiated with continuous-wave laser radiation in the spectral absorption region of the NPs. A model is constructed that takes into account optical and photothermal effects associated with TiN NPs, i.e., scattering, absorption, and heat exchange in water. A semiconductor laser diode with a wavelength of 808 nm and a power of 0.35 W is used for photoheating of an aqueous suspension of NPs. It is found that the magnitude of photoheating of the aqueous NP suspension flow increases with synchronization of the scanning laser beam and moving flow of TiN NPs.

We study a possibility of using an accelerator-driven system of the Prometheus proton therapy complex to obtain medical isotopes. The electronuclear setup is simulated using the Geant4 software package. The yield curves of the ⁹⁹Mo isotope are calculated, and the results of simulating a number of other isotopes are presented.

The Geant4 software package is used to calculate hadronic and electromagnetic inelastic cross sections of interactions of relativistic heavy nuclei as functions of the center-of-mass energy per nucleon. It is shown that in the energy range of the NICA accelerator complex, inelastic collisions result from electromagnetic dissociation of colliding nuclei.

A method for determining angular characteristics of a spread of a pencil proton beam, associated with the nonuniform distribution of the initial momenta of particles, is examined. Considering this phenomenon is crucial when planning patient irradiation and conducting radiobiological experiments, because angular characteristics directly affect the size of the field during particle transport through air or other media. Experimental data are also compared with Monte Carlo simulations performed with the TOPAS MC software package using the obtained parameters. The results demonstrate good agreement and validate the described method.

The effective lifetime for the decay (B_{s}^{0} to J{text{/}}psi K_{S}^{0}) is reported using the data from pp collision at centre of mass energy (sqrt s ) = 13 TeV recorded by CMS experiment at the LHC during 2016, 2017 and 2018. The data sample corresponds to an integrated luminosity of 140 fb^–1. The measurement uses the two-dimensional unbinned maximum likelihood (UML) fit to B-invariant mass and the decay time to extract the observable. Effective lifetime is measured as 1.59 ( pm ) 0.07(stat) ( pm ) 0.03(syst) ps, which is in good agreement with the standard model prediction and stands as the most precise result to date.