1,067 research outputs found

    Clustering in light nuclei in fragmentation above 1 A GeV

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    The relativistic invariant approach is applied to analyzing the 3.3 A GeV 22^{22}Ne fragmentation in a nuclear track emulsion. New results on few-body dissociations have been obtained from the emulsion exposures to 2.1 A GeV 14^{14}N and 1.2 A GeV 9^{9}Be nuclei. It can be asserted that the use of the invariant approach is an effective means of obtaining conclusions about the behavior of systems involving a few He nuclei at a relative energy close to 1 MeV per nucleon. The first observations of fragmentation of 1.2 A GeV 8^{8}B and 9^{9}C nuclei in emulsion are described. The presented results allow one to justify the development of few-body aspects of nuclear astrophysics.Comment: 7 pages, 8 figures, 3 tables, Nuclear Physics in Astrophysics-2, 16-20 May, 2005 (ATOMKI), Debrecen, Hungar

    Fragmentation of relativistic nuclei in peripheral interactions in nuclear track emulsion

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    The technique of nuclear track emulsions is used to explore the fragmentation of light relativistic nuclei down to the most peripheral interactions - nuclear "white" stars. A complete pattern of therelativistic dissociation of a 8^8B nucleus with target fragment accompaniment is presented. Relativistic dissociation 9^{9}Be2α\to2\alpha is explored using significant statistics and a relative contribution of 8^{8}Be decays from 0+^+ and 2+^+ states is established. Target fragment accompaniments are shown for relativistic fragmentation 14^{14}N\to3He+H and 22^{22}Ne\to5He. The leading role of the electromagnetic dissociation on heavy nuclei with respect to break-ups on target protons is demonstrated in all these cases. It is possible to conclude that the peripheral dissociation of relativistic nuclei in nuclear track emulsion is a unique tool to study many-body systems composed of lightest nuclei and nucleons in the energy scale relevant for nuclear astrophysics.Comment: 15 pages, 4 figures, 4 tables, conference: Relativistic nuclear physics: from Nuclotron to LHC energies, Kiev, June 18-22, 200

    The policy of import substitution as the basis for economic security and well-being of society

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    The study presents the analysis of import substitution opportunities on separate branches of economic activity, preceding the realization of import substitution policy with the aim to support national economic security, which is essential for the contemporary society welfare insurance. Currently, social well-being is considered to be the reflection of economic activity, the instrument of state influence on the society, as well as an indicator of the social security system. Due to the fact that Russia is integrated into the world economy, the foreign-economic policy currently is playing an important role in the development of national security and the state's interest to the spheres of economy considering external and internal threats. Decline in external economic conditions may result in serious consequences for the functioning and development of the country as well as for the trade and investment activities, which will further lead to the decline in export, withdrawal of capital, recession of industrial production, trade and investment sphere, fall of GDP and living standards. Thus, considering the current state of instability in the world economy and the growing political tension in relation to Russian Federation, the measures to increase economic security in the country should be taken. The policy of import substitution is considered to be one of the major solutions nowadays

    SEM and AFM studies of two-phase magnetic alkali borosilicate glasses

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    The morphology and composition of four types of two-phase alkali borosilicate glasses with magnetic atoms prepared by inductive melting have been studied. The results of scanning electron microscopy point to uniform distribution of Na, Si, and O atoms in these samples whilemagnetic iron atoms formball-shaped agglomerates. The magnetic properties of these agglomerates have been confirmed by magnetic force microscopy. Atomic force microscopy had shown that in these samples two different morphological structures, drop-like and dendrite net, are formed. The formation of dendrite-like structure is a necessary condition for production of porous magnetic glasses. The obtained results allowus to optimize the melting and heat treatment processes leading to production of porous alkali borosilicate glasses withmagnetic properties. The first results for nanocompositematerials on the basis ofmagnetic glasses containing the embedded ferroelectrics KH2PO4 demonstrate the effect of applied magnetic field on the ferroelectric phase transition. The morphology and composition of four types of two-phase alkali borosilicate glasses with magnetic atoms prepared by inductive melting have been studied. The results of scanning electron microscopy point to uniform distribution of Na, Si, and O atoms in these samples whilemagnetic iron atoms formball-shaped agglomerates. The magnetic properties of these agglomerates have been confirmed by magnetic force microscopy. Atomic force microscopy had shown that in these samples two different morphological structures, drop-like and dendrite net, are formed. The formation of dendrite-like structure is a necessary condition for production of porous magnetic glasses. The obtained results allowus to optimize the melting and heat treatment processes leading to production of porous alkali borosilicate glasses withmagnetic properties. The first results for nanocompositematerials on the basis ofmagnetic glasses containing the embedded ferroelectrics KH2PO4 demonstrate the effect of applied magnetic field on the ferroelectric phase transition.DAA

    Search for a signal on intermediate baryon systems formation in hadron-nuclear and nuclear-nuclear interactions at high energies

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    We have analyzed the behavior of different characteristics of hadron-nuclear and nuclear-nuclear interactions as a function of centrality to get a signal on the formation of intermediate baryon systems. We observed that the data demonstrate the regime change and saturation. The angular distributions of slow particles exhibit some structure in the above mentioned reactions at low energy. We believe that the structure could be connected with the formation and decay of the percolation cluster. With increasing the mass of colliding nuclei, the structure starts to become weak and almost disappears ultimately. This shows that the number of secondary internuclear interactions increases with increasing the mass of the colliding nuclei. The latter could be a reason of the disintegration of any intermediate formations as well as clusters, which decrease their influence on the angular distribution of the emitted particles.Comment: 2 pages and one figur

    Topology of "white" stars in relativistic fragmentation of light nuclei

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    In the present paper, experimental observations of the multifragmentation processes of light relativistic nuclei carried out by means of emulsions are reviewed. Events of the type of "white" stars in which the dissociation of relativistic nuclei is not accompanied by the production of mesons and the target-nucleus fragments are considered. A distinctive feature of the charge topology in the dissociation of the Ne, Mg, Si, and S nuclei is an almost total suppression of the binary splitting of nuclei to fragments with charges higher than 2. The growth of the nuclear fragmentation degree is revealed in an increase in the multiplicity of singly and doubly charged fragments with decreasing charge of the non-excited part of the fragmenting nucleus. The processes of dissociation of stable Li, Be, B, C, N, and O isotopes to charged fragments were used to study special features of the formation of systems consisting of the lightest α\alpha, d, and t nuclei. Clustering in form of the 3^3He nucleus can be detected in "white" stars via the dissociation of neutron-deficient Be, B, C, and N isotopes.Comment: 20 pages, 3 figures, 9 tables, conference: Conference on Physics of Fundamental Interactions, Moscow, Russia, 1-5 Mar 2004.(Author's translation

    Electromagnetic dissociation of relativistic 8^8B nuclei in nuclear track emulsion

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    Experimental data on fragmentation channels in peripheral interactions of 8^8B nuclei in nuclear track emulsions are presented. A detailed analysis made it possible to justify selections of events of the electromagnetic-dissociation process 8^8B 7\to^7Be + \emph{p} and to estimate its cross section. Events of 10^{10}C peripheral dissociation that were observed in the same exposure are described.Comment: 12 pages, 10 figures, 4 tables, Published in Phys.Atom.Nucl.72:690-701,200

    Exposure of Nuclear Track Emulsion to a Mixed Beam of Relativistic 12^{12}N, 10^{10}C, and 7^7Be Nuclei

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    A nuclear track emulsion was exposed to a mixed beam of relativistic 12^{12}N, 10^{10}C, and 7^7Be nuclei having a momentum of 2 GeV/cc per nucleon. The beam was formed upon charge exchange processes involving 12^{12}C primary nuclei and their fragmentation. An analysis indicates that 10^{10}C nuclei are dominant in the beam and that 12^{12}N nuclei are present in it. The charge topology of relativistic fragments in the coherent dissociation of these nuclei is presented.Comment: ISSN 1063-7788, Pleiades Publishing, Ltd., 201

    Impact of climate change on the ground thermal regime in the lower Lena region, Arctic central Siberia

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    This paper presents the results of 30 years of permafrost thermal monitoring in the Tiksi area in the eastern Russian Arctic. At a stone ridge site, the mean annual temperatures in the upper 30 m of the ground have increased by 1–2.4 C compared to the first years of observations, with trends of C/yr. At the same time, its change was uneven. In the last 20 years, the rate of increase has increased compared with the first decade of observations. At wet tundra sites in the foothill plain, the mean annual temperatures at the top of permafrost have increased by 2.4–2.6 C between 2005 and 2022 at rates of 0.11–0.15 C/yr, and the active layer thicknesses have increased at rates of 0.05–0.41 cm/yr

    The use of ultrasonic cavitation for near-surface structuring of robust and low-cost AlNi catalysts for hydrogen production

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    Ultrasonically induced shock waves stimulate intensive interparticle collisions in suspensions and create large local temperature gradients in AlNi particles. These trigger phase transformations at the surface rather than in the particle interior. We show that ultrasonic processing is an effective approach for developing the desired compositional gradients in nm-thick interfacial regions of metal alloys and formation of effective catalysts toward the hydrogen evolution reaction
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