卷 82, 编号 5 (2019)

Detection of antineutrino by the reaction of the inverse β-decay can be used for an independent monitoring of a nuclear reactor power. DANSS detector is located directly under a commercial WWER-1000 reactor and counts up to 5000 antineutrino per day, providing the accuracy of 1.5% in 2 days of the flux measurement. A powerful system of the passive and active shielding in combination with the fine spatial segmentation of the detector allows to diminish the contribution of the background processes to a level, negligible in comparison to the statistical error. The influence of the nuclear fuel composition on the neutrino flux can be accounted for based on the input from the NPP staff.

Using the available experimental data, production cross sections of the most stable nuclei have been calculated for the proton-induced fission of ²³⁸U and ²³²Th at 12, 20, 35, 50, 96 MeV in case of ²³⁸U and at 8, 9.3, 12, 19.55, 32.2, 44.7, 53 MeV for ²³²Th. The analysis has been carried out for the fission fragment mass ranges corresponding to N/Z ratios in the ranges 1.33 ± 0.09 and 1.32 ± 0.08 for ²³⁸U and ²³²Th respectively. Results have been compared with the ones generated indirectly by employing GEF nuclear reaction code, version 2017/1.1. From the production cross sections point of view, for the same energy, ²³²Th is found to be a better target than ²³⁸U for producing nuclei A around the symmetric mass peak, while ²³⁸U comes out to be a better one than ²³²Th for producing the fission fragments around the asymmetric peaks of the mass distribution.

Reduced probabilities for intra/interband E1 and E2 transitions to alternating-parity states of the yrast and first nonyrast bands in ¹⁵⁰Nd, ¹⁵⁴Sm, ^{154, 160}Gd, and ^{162, 164}Er lantanide and ²³²Th and ^236,238u actinide nuclei are studied. The values calculated for B(E1) and B(E2) are compared with available experimental data. Variations in the surface deformation of nuclei upon a collective excitation are taken into account.

The cross section σ(E_ν) for solar-neutrino capture by the ⁷⁶Ge nucleus is calculated. The effect of Gamow-Teller resonances on the rate of neutrino capture in the reaction ⁷⁶Ge (ν, e⁻)⁷⁶ As is studied. It is shown that the contribution of high-lying Gamow-Teller resonances to the charge-exchange strength function increases the rate of solar-neutrino capture by 25% to 50%, depending on the normalization method and on the inclusion of the quenching effect.

The neutrino/antineutrino flux ratios (\({\nu _e}/{\overline \nu _e}\) and \({\nu _\mu }/{\overline \nu _\mu }\)) and the flavor ratio \(\left( {{\nu _\mu } + {{\overline \nu }_\mu }} \right)/\left( {{\nu _e} + {{\overline \nu }_e}} \right)\) clearly demonstrate the distinctions between the predictions of hadronic-interaction models for the production spectra of pions and kaons, which are the main sources of atmospheric neutrinos in the region of E_ν ≲ 500 TeV. The values of the \({\nu /\overline \nu }\) ratio are sensitive to variations in the π⁺/π⁻, π/K, and K⁺/K⁻ meson ratios, which are determined by the cross sections for inclusive meson-production processes in hadron-nucleus (hA) collisions; the elemental composition of cosmic rays also exerts influence, through the p/n ratio, on the development of hadronic cascades and on the neutrino ratios. The difference in \({\nu /\overline \nu }\) and in the flavor ratio for a number of hadronic-interaction models is shown on the basis of calculating neutrino fluxes at energies in the range between 10² and 10⁸ GeV. A comparison of the calculated results with new experimental data shows the reliability of this calculation, which, on the whole, reflects correctly the mechanism of atmospheric-neutrino production. The spectra of atmospheric muon neutrinos from calculations based on the Kimel-Mokhov, SIBYLL 2. 1, and EPOS LHC models describe fairly well experimental results. At energies in the range of 1–500 TeV, the curves calculated within these models combined with the Hillas-Gaisser spectrum are close to the best fit to data from measurements in the IceCube experiment.

As a group—theoretic foundation of gravity, it is considered an affine-Goldstone nonlinear model based upon the nonlinear realization of the global affine symmetry spontaneously broken at the Planck scale to the Poincaré symmetry. It is shown that below this scale the model justifies and elaborates an earlier introduced effective field theory of the quartet-metric gravity incorporating the gravitational dark substances emerging in addition to the tensor graviton. The prospects for subsequent going beyond the nonlinear model above the Planck scale are indicated.

The present review article describes the role of radiation technologies in various realms of human activities, including fundamental science, industry, agriculture, and medicine. The development of radiation technologies in the world and in Russia is compared. The total number of ionizing-radiation sources in the world is approximately 11 million units, most of them being radioactive sources (about six to seven million units) and x-ray facilities (about four million units). The number of high-technology facilities (such as accelerators and tomography units of various types) that employ ionizing radiation does not exceed 200 thousand units. In Russia, there are more than 153 thousand units of such instruments and facilities. They include about 64700 units employing x-ray radiation; about 79700 radioisotope devices and setups, reactors, and radioactive-waste storage facilities; and 471 accelerators. The most promising lines of development of radiation technologies in Russia are analyzed from the strategic and economic points of view.

The Single-State HORSE (SS-HORSE) method is applied to studying resonant scattering. The method relies on microscopic calculations of nuclear spectra on the basis of the No-Core Shell Model with realistic nucleon-nucleon interactions and does not involve model approximations. The 3/2⁻ and 1/2⁻ resonances of the ⁵Li and ⁵He nuclei are investigated within the SS-HORSE method. The possible existence of a resonance in the four-neutron system is explored.