Analysis of mechanical testing and microstructural investigations of the irradiated VVER-440 reactor pressure vessel (RPV) metal before and after annealing carried out in the frameworks of the international project “PRIMAVERA” is presented. The role of chemical elements (Cu and P) was studied in relation to irradiation embrittlement of the VVER-440 RPV weld metal in the initial state, after recovery annealing and after postannealing irradiation. It was shown that under primary irradiation, copper atoms formed small clusters (size ~1‒2 nm) which also include P, Si and Mn atoms. Phosphorus atoms also segregated on copper clusters, dislocations, grain boundaries, and additionally formed phosphorus clusters and atmospheres. Under thermal annealing at 475°C, the irradiation-induced copper-enriched and phosphorus clusters partially dissolved, increasing the copper concentration in the annealed metal, which was significantly lower compared to the unirradiated material. Since most copper atoms after annealing were not contained in the ferritic matrix but in precipitates, the contribution of copper atoms to an increase in the ductile-to-brittle transition temperature under re-irradiation was minimized and so hardening and embrittlement after subsequent post-annealing irradiation were lower than under primary irradiation.

Within a model that includes a plasma, a vacuum gap and a wall of the tokamak chamber, the conversion of a plasma current poloidal magnetic field into the kinetic energy of runaway electrons (REs) in the termination phase of the discharge disruption is investigated. The equation for the change in the kinetic energy of REs is obtained, that allows to determine the change in the specified energy in the general case with the known REs density profile, REs current density and the magnetic field. For a flat plasma current density profile, an upper estimate for the REs kinetic energy and conversion was obtained.

Within the ATLAS Higgs boson working group (HWW), a study of events with two electrons and two muons in the H → WW → lνlν decay channel at 13 TeV in the ATLAS experiment at the LHC is performed. The analysis uses complete data sample accumulated during 2015–2018 exposures which corresponds to integrated luminosity 139 fb⁻¹. Based on MC simulations, selection criteria for signal events as well as for control kinematical region for main Drell–Yan background are suggested. Expected upper limits on the heavy Higgs boson production cross section are calculated in the framework of several models. It turned out that they are only a bit worse than those obtained from the analysis of events with one electron and one muon for the H → WW → lνlν decay channel.

According to modern theories parameters of neutral mesons such as their mass and width are tightly related to medium in which mesons are present. Experimental data on the study of mesons in a nuclear medium are in demand for the development of theoretical models describing processes in the field of nonperturbative quantum chromodynamics (QCD). In the Hyperon-M experiment at the U70 accelerator, measurements are made of the masses and widths of neutral mesons produced in meson-nuclear interactions on various nuclei. This paper describes a technique for precision measurement of the parameters of neutral mesons, presents the results on the measurement of the mass and width of the ω(782)-meson and preliminary results on the measurement of the mass and width of the f (1270)-meson. The measurements indicate that there is no dependence of the quantities under study on the nuclear environment.

The new coordinate-tracking detector TREK based on multiwire drift chambers is being developed in the National Research Nuclear University MEPhI to study the muon component of extensive air showers. Its prototype named the coordinate-tracking unit based on drift chambers (CTUDC) has been designed. Investigation of the multiparticle events registered by the unit has shown all the complexity of reconstruction of such events. The analytical reconstruction methods applied earlier demonstrate their inefficacy in dealing with these events. A new approach based on deep learning methods is being developed to solve this problem. The paper presents the results of application of artificial neural networks to experimental data obtained by the CTUDC.

The differential energy spectrum of cosmic rays in the energy range of 3 · 10¹⁴–3 · 10¹⁸ eV and the corrected dependence of the mean depth of the maximum ⟨X_max⟩ of an extensive air shower (EAS) inside the wide energy range of 10¹⁵–3 · 10¹⁷ eV have been obtained by the data of the Tunka-133 array for 7 years of operation (2009–2017) and the TAIGA-HiSCORE array for the 2019−2020 season of operation. At the extremely high energy our results agree with the results of the Pierre Auger observatory based on direct measurements of the maximum depth by the observation of fluorescent light from EAS. The recalculation from the ⟨X_max⟩ to the parameter ⟨ln A⟩, which characterizes the average composition of the primary cosmic rays is presented.