The paper presents the results of experiments on measuring the cross sections for elastic scattering and nucleon transfer channels in the 6Li+9Be reaction at an incident energy of 68 MeV: 9Be(6Li,6Li)9Be, 9Be(6Li,7Li)8Be, 9Be(6Li,7Li)8Be2+, 9Be(6Li,8Li)7Be, 9Be(6Li,7Be)8Li. The aim is to reveal the manifestation of the cluster structure of 9Be. Theoretical analysis of the contributions of one-step and two-step neutron transfer mechanisms is performed using the distorted wave Born approximation method with the Fresco code. Good agreement between the calculations and the experimental data was obtained for the channels of elastic scattering 9Be(6Li,6Li)9Be, neutron 9Be(6Li,7Li)8Be and proton transfer 9Be(6Li,7Be)8Li, as well as the transfer of two neutrons 9Be(6Li,8Li)7Be. It is shown that the dineutron cluster transfer mechanism makes a dominant contribution to the 9Be(6Li,8Li)7Be reaction channel at forward angles.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23070425

Calculations have been made for the existing magnet of the MAVR spectrometer and the results are compared with experimental data. A model of a new magnet is proposed that makes it possible to increase the maximum magnetic rigidity of particles up to 2.5 T m. The quality of focusing of beams of different rigidity onto the plane of the detectors for two models is compared.

— This paper presents a complex interpretation of structural–petrological studies and new geochemical and isotope–geochronological data on the Paleoarchean metamorphic and metaintrusive rocks of Mts. Rymill and Bloomfield in the northern part of the granite-greenstone Ruker terrane (Prince Charles Mountains, East Antarctica). The detailed sequence of changing Archean tectonomagmatic processes in the northern block of the Ruker area has been revealed and the main stages of tectonic deformations and metamorphism of Precambrian geodynamic evolution are shown, which is a key for the understanding of the geological evolution of the Archean metamorphic complexes of East Antarctica and ancient Earth’s regions. The northern part of the Ruker Terrane is composed of the Meso-Neoarchean granite–gneiss domes, which are tectonically framed by fragments of greenstone belt of the metavolcanosedimentary Meso-Neoarchean Menzies Series. The detached blocks or packages of sheets of metavolcanosedimentary sequences are a section of weakly metamorphosed intermediate–felsic sandstones, quartzites, and micaceous schists. An assemblage of rocks spans a significant period from 3.2 to 2.5 Ga. The composition of the Mesoarchean granite–gneiss domes of the Mawson Series (3.2–3.1 Ga) corresponds to those of ancient granitoids, is similar to tonalite–trondhjemite–granodiorite (TTG) complexes, and is comparable with similar associations of ancient cratons of Australia, Canada, and Fennoscandia. The rocks of the Mawson Series are polymetamorphic and a significant part of their recrystallization is related to the Mesoarchean stage of metamorphism, whose end is comparable with the formation of the Meso-Neoarchean blocks of the granite–gneiss association of the TTG dome of ~2.8 Ga identified by the author. The age of the striking tectonothermal event of ~2.7 Ga is determined by overgrowths of zircons from the TTG gneisses. The Mawson Orthogneiss and TTG gneisses are compared with intraplate A‑granitoids and are ascribed to low-Ti high-K Archean granitoids. The geochemistry of the rocks indicates that primary melts of the Meso-Archean Mawson Orthogneiss formed in crust at shallower depths ( P < 8–10 kbar) in comparison with Meso-Archean TTG gneisses, whose formation is possibly caused by the increasing thickness of the crust followed by its extension and thinning at a boundary of ~2.5 Ga.

Mountain frame of the Denman Glacier is a little explored and at the same time an most essential region of East Antarctica in the context of studying the Precambrian geological history and geodynamic evolution of the Archean protocratons of East Antarctica. Present paper provides original U–Pb isotope geochronology data from zircons of metamorphic and intrusive rocks sampled from the Denman Glacier western flank outcrops. Geodynamic interpretation of geochronology data are also presented. For the first time, for such East Antarctic location, crystallization time (3355 ± 5.4 Ma) for plagiogneisses magmatic protolith was obtained. The Davis Paleoarchean protocraton in the Archean time interval of evolution was subject to multistage polymetamorphism in the intervals ~3100–3000, 2900–2800 Ma ago. The late stage is associated with crustal extension, which is marked by syntectonic intrusion of ultramafic dikes and pyroxenite sills (2827 ± 6 Ma). The formation time of granite veins and subalkaline granitoid pluthons corresponds to the time of tectono-thermal activisation in the interval of 550–510 Ma traced also along significant part of East Antarctic (the Pan-African tectono-thermal event). The Davis terrane shows a significant similarity in the time of formation and evolution of geodynamic processes with the Paleo-Mesoarchean protocratons of East Antarctica, as well as India and Australia.

The energy spectra of alpha particles emitted at an angle of 0 $${}^{\circ}$$ in the interaction of 400-MeV $${}^{56}$$ Fe ions with $${}^{238}$$ U, $${}^{181}$$ Ta, and $${}^{9}$$ Be targets were measured by means of a high-resolution magnetic analyzer (MAVR, which is the acronym of the Russian name of this setup). The energy spectra of charged particles ranging from Li to Ne were also measured. The experimental data obtained in this way indicate that the emission of alpha particles is a dominant process in the above reactions. Particles of high energy, up to those in the vicinity of the so-called kinematical limit for two-body reactions, were observed with a rather high yield. The sensitivity of the experimental procedure that employed the aforementioned magnetic analyzer made it possible to observe events characterized by cross-section values smaller by six to eight orders of magnitude than that at the maximum of the spectrum. The cross section for the production of light particles is shown to be dependent on their binding energy in the target. The experimental data obtained in this study were analyzed with aid of the moving-source model.

The results of experiments on measuring the energy spectra of alpha particles in reactions with heavy ions are presented. The measurements were performed using the high-resolution magnetic analyzer MAVR with beams of 48 Ca (280 MeV) and 56 Fe (320 and 400 MeV) on 181 Ta and 238 U targets at an angle of 0°. A strong dependence of the double differential cross sections for production of alpha particles on the atomic number of the target nucleus was observed, which indicates that fast alpha particles are mainly emitted from the target nucleus; this conclusion was also confirmed by calculations within the time-dependent Schrödinger equation approach. An analysis of the obtained experimental data was carried out within the model of moving sources modified to consider the kinematic limits for two-body and three-body exit channels.

The energy spectra of alpha particles from reactions induced by 280-MeV $${}^{48}$$ Ca beams incident to $${}^{181}$$ Ta, $${}^{197}$$ Au, and $${}^{238}$$ U targets were measured at an angle of 0 $${}^{\circ}$$ by means of a high-resolution magnetic analyzer (MAVR setup). The sensitivity of the procedure used made it possible to measure alpha-particle yields that are five to six orders of magnitude less than the maximum yield. The cross section for the formation of alpha particles is shown to be dependent on their binding energy in the target nucleus. The experimental data obtained from these measurements were analyzed on the basis of the model of two- and three-body reaction channels and the model of moving sources.

Inclusive energy spectra have been measured for light charged particles emitted in the bombardment of Ta target by48Ca ions at 261 MeV and 471 MeV. The reaction products were analyzed and detected by means of a (∆E-E) telescope placed in the focal plane of a magnetic spectrometer located at forward angles with respect to the beam direction. In all the reactions studied light charged particles with an energy close to the respective calculated kinematic limit for a two-body exit channel are produced with relatively great probability. The results obtained make it possible to draw some conclusions about the reaction mechanism involving the emission of light charged particles.

The differential cross sections for alpha-particle emission at an angle of 0 $${}^{\circ}$$ in the reactions induced by a 6-MeV/nucleon $${}^{56}$$ Fe beams incident to $${}^{238}$$ U and $${}^{181}$$ Ta targets were measured versus the alpha-particle energy by means of a high-resolution magnetic analyzer (MAVR setup). The resulting spectra were found to contain fast alpha particles of energy corresponding to the two- and three-body exit reaction channels, including alpha particles of energy close to the two-body kinematical limit. The data obtained in this experiment were analyzed on the basis of the moving-source model. The emission of nonequilibrium alpha particles in the forward direction from the heavier target nucleus upon the complete or incomplete fusion of nuclei was revealed within the time-dependent quantum approach.

Neutron-removal cross-section ( σ-xn ) measurements of neutron-rich light nuclei were performed on the COMBAS fragment-separator with a multi-detector Si telescope at intermediate energies (22-34) MeV/nucleon. The removals of one neutron from8Li and9Be, two neutrons from6 He and10 Be and four neutrons from 8 He were observed from the reactions on a Si-CsI(Tl) telescope. Results of σ-xn for6 He,8 He,8 Li,9 Be and10 Be nuclei were obtained and compared with those of previously measured data. The data indicate that4 He is a good core within6 He and8 He. Furthermore, we found that9,10 Be nuclei disintegrated by one- and two- neutron removal reaction, respectively.

The results of an experiment carried out on the MAVR high-resolution magnetic spectrometer and devoted to studying neutron transfer in the $${}^{18}\textrm{O}+^{181}$$ Ta reaction at the projectile energy of 10 MeV per nucleon are presented. A theoretical analysis of the experimental cross sections is performed for the neutron transfer mechanism by means of a time-dependent approach based on solving the time-dependent Schrödinger equation. The dynamics of the neutron transfer process is described, and the probabilities for the population of unoccupied neutron levels in the $${}^{19}$$ O nucleus are determined.

Charged-particle trajectories in the MAVR high resolution magnetic spectrometer are simulated. The latter has been constructed at the U400 accelerator for purifying the incident beam and identifying the products of nuclear reactions induced by the beams of stable and radioactive nuclei. In this paper we present the MAVRPC++ software package, aimed at reconstructing the spectrometer focal plane, optimizing the fields of quadrupole and dipole magnets, and estimating the solid-angle acceptance for secondary particles.

A time-of-flight system was created to register the reaction products and perform correlation measurements on a high-resolution magnetic analyzer (MAVR). The facility is located on the channel of the extracted beam of the U-400 cyclotron at the Laboratory of Nuclear Reactions JINR. The results of measuring the parameters of the time-of-flight spectrometer obtained on the basis of measuring the spontaneous fission fragments velocities of 252Cf are described. In addition, the results of the measurement of fission fragments in the 48Ca+238U reaction are presented. In this case, two time-of-flight arms were used, with the help of it is planned to carry out correlation measurements of induced fission fragments of a complex system. The created system also makes it possible to carry out correlation (three particles) measurements of fission fragments with particles registered in the focal plane of the MAVR magnetic spectrometer. Another purpose of the described system is to register elastically scattered ions, which is used as a monitoring system for the quality and composition of the beam hitting on the target of the MAVR facility.

The solubility of CaF2 in different chloride and chloride‒fluoride melts has been studied in order to choose appropriate fluxes for crystallization of epitaxial fluorite layers. It is shown that the advantages of the 0.6NaCl–0.4NaF composition over the well-known CaCl2–CaF2 flux are the high thermal stability, lower (by half) temperature gradient of solubility, and possibility for reducing the growth temperature by 100°С. Seed crystallization of fluorite in the CaF2–(0.6NaCl–0.4NaF) flux has been performed both using the temperature reduction method and under the temperature gradient conditions.