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[en] The formation of luminescent colour centres in the LiF crystal under the action of femtosecond pulses of the first harmonic of a Ti : sapphire laser is experimentally studied. The experiments were carried out at low- and high-aperture focusing of radiation. The effect of both single pulses and multi-pulse trains on the crystals was studied. Channelling of laser radiation in the waveguides, induced by the filaments of the first pulses, is found. The multiphoton mechanism of interband absorption is confirmed. The optimal conditions of laser impact for designing luminescent emitters in the LiF crystal are determined. (interaction of laser radiation with matter. laser plasma)

[en] We investigate the neutrino helicity flip under supernova core conditions, where the left-handed neutrinos being produced can be converted into right-handed neutrinos sterile with respect to weak interactions owing to the interaction of the magnetic moments with plasma electrons and protons. In calculating the probability for the conversion neutrino scattering by plasma components, we take into account the polarization effects attributable to both electrons and protons in the photon propagator. Based on realistic models with radial distributions and time evolution of physical parameters in a supernova core, we have obtained upper limits on the Dirac neutrino magnetic moment averaged over flavors and time from the condition that the influence of the right-handed neutrino emission on the total cooling time scale should be limited.

[en] Neutrino production of electron–positron pairs via the processes $v\stackrel{¯<!--\; ??\; -->}{v}$ → e⁻e⁺ and ν → νe⁻e⁺ in a moderately strong magnetic field is investigated. Under these conditions electrons and positrons can be produced in the states corresponding to excited Landau levels. The results can be used for calculating the efficiency of the electron–positron plasma production by neutrinos in the conditions of the accretion disk around a Kerr black hole.

[en] A mechanism generating a natal-neutron-star kick and involving only standard neutrinos is discussed. In this mechanism, the neutrino effect on the plasma of the supernova-core envelope in a magnetorotational explosion accompanied by the generation of a strong toroidal magnetic field leads to a redistribution of the magnetic field B in the “upper” and “lower” hemispheres of the supernova-core envelope. The emerging asymmetry of the magnetic-field pressure may generate a natal-pulsar kick

[en] The neutrino self-energy operator Σ(p) in a magnetic field is calculated for the case of high-energy neutrinos, this corresponding to the crossed field approximation. The probability of the neutrino decay ν ^→ e^-W⁺ is found by using the imaginary part of the operator Σ(p). A simple analytic result is obtained in the parameter region that is the most interesting from the physical point of view and which was not considered earlier. The contribution of an external magnetic field to the neutrino magnetic moment is calculated. The result obtained here for this contribution corrects formulas available previously

[en] The ν_L^→ ν_R^→ ν_L double conversion of the Dirac neutrino helicity is analyzed under supernova conditions, in which case the first stage is due to the interaction of the neutrino magnetic moment with plasma electrons and protons in the supernova core, while the second stage is caused by a resonance neutrino-spin flip in the magnetic field of the supernova envelope. It is shown that, if the neutrino has a magnetic moment in the range 10^-13 μ_B < μ_ν < 10^-12 μ_B and if a magnetic field of strength 10¹³ G exists between the neutrinosphere and the region of shock-wave stagnation, an additional energy on the order of 10⁵¹ erg, which is sufficient for stimulating a damped attenuated shock wave, can be injected in this region within the stagnation time.

[en] High-resolution spectra of the $2{\mathrm{\nu <!--\; ??\; -->}}_2-<!--\; ???\; -->{\mathrm{\nu <!--\; ??\; -->}}_2$ hot band of the ¹⁵NH₂D and ¹⁵NHD₂ molecules are investigated for the first time. The analysis is carried out based on the ground state combination difference method. As a result, the energy structure of the inversion-vibrational state ($v_2$ = 2, s) has been obtained for each of the molecules under study and more than 480 vibrational–rotational transitions belonging to the studied hot bands have been found. Values of the upper energy levels determined based on the position of lines are used as initial data for the determination of spectroscopic parameters of the ($v_2$ = 2, s) state.

[en] Tree-level two-point jf → j′f′ transitions amplitudes in a constant uniform magnetic field of an arbitrary strength and in charged fermion plasma, for different combinations of scalar, pseudoscalar, vector, and axial-vector vertices are calculated. The obtained results are applied to analysis of the neutrino photoproduction process, γe → $ev\stackrel{¯<!--\; ??\; -->}{v}$, taking account of a possible resonance on the virtual electron in the conditions of dense strongly magentized plasma.

[en] The development of new promising technologies based on coal fuel is certainly topical. This article is devoted to application of new technology of gas and fuel oil replacement by mechanically activated micronized coal in power engineering: ignition and stabilization of pulverized coal flame combustion. Enhancement of coal reactivity at its grinding with mechanical activation is associated with an increase in the reaction rate of carbon material. The process of combustion was studied on the 1-MW setup with tangential scroll supply of pulverized coal-air mixture and cylindrical reaction chamber. Experiments were carried out by using brown coals. Coal, ground by the standard boiler mill, was fed to the input of high-energy mills and then was directed to the scroll inlet of the burner-reactor with the transport air. The suspension was ignited by a gas igniting device with the power of 50 kW. Experimental studies on air gasification of micronized coal were conducted in the reaction chamber at the temperature of 1000-1200 °C and air excess ratio α = 0.5. Intensive mechanical activation of coals led to increase the chemical activeness. This effect can be used for development of new highly boosted processing methods for coals with various levels of metamorphism. The obtained results of visualization were used to train the state-of-art deep convolutional neural network. It was shown that the developed neural network was able to automatically determine the combustion regimes from flame images. (paper)