JINR Research Articles

Development and Construction of Track and Identification Systems for Experiments Aimed at Studying Extreme Properties of Nuclear Matter in Nucleus–Nucleus Collisions

Investigation of properties of nuclear matter at extremely high temperature and/or extremely high baryon densities under laboratory conditions is one of the fundamental lines of research in high-energy physics. Throughout the past decades, such investigations have been performed in collisions of ultrarelativistic heavy ions in several experiments at modern accelerator complexes, including the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL, USA) and the Large Hadron Collider (LHC) at CERN (Switzerland). In the near future, it is also planned to launch investigations of this kind at the FAIR (Facility for Antiproton and Ion Research at Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, Germany) and NICA (Nuclotron-based Ion Collider fAcility at Joint Institute for Nuclear Research (JINR), Dubna, Russia) accelerators. In order to implement such investigations, it is necessary to create sophisticated detector systems that are able to record events featuring high-multiplicity product particles and to measure reliably their properties. The present article gives a brief survey of all detector systems that have already been created and are being developed at Laboratory of Relativistic Nuclear Physics at Petersburg Nuclear Physics Institute (National Research Center Kurchatov Institute) for the PHENIX (BNL, USA), ALICE (CERN, Switzerland), and CBM (GSI, Germany) experiments aimed at studying nuclear matter under extreme conditions.

Modern Methods of Neutron Radiography and Tomography in Studies of the Internal Structure of Objects

The fundamentals, experimental possibilities, and applications of the methods of neutron radiography and tomography in studies of the structural features of large objects in various fields are reviewed. The main principles of neutron imaging are considered. Specialized experimental stations at the National Research Centre “Kurchatov Institute” and the Joint Institute for Nuclear Research are described, and their main parameters are presented. The experimental capabilities of these neutron facilities, including methodological approaches to variation of the neutron radiographic contrast with neutron energy dispersion, are described. A detailed review of the scientific results obtained on neutron radiography and tomography facilities is presented; these results concern engineering and technological objects, internal structure of meteorites, paleontological samples, and cultural heritage objects.

Small-Angle Neutron Scattering at the Pulsed Reactor IBR-2: Current Status and Prospects

Neutron diffraction studies on the small-angle neutron spectrometer YuMO (Joint Institute for Nuclear Research, Dubna), based on the IBR-2 pulsed reactor, have been reviewed. The main parameters of small-angle spectrometers, based on the time-of-flight technique, are considered. It is shown that the flux on sample is the key parameter of the spectrometers based on pulsed sources, which makes it possible (along with application of a multidetector system) to expand the dynamic range of scattering vector magnitudes. The history of the setting up of the first small-angle instrument based on pulsed sources is overviewed. The directions of development of small-angle spectrometers are shown. The results of YuMO studies in the fields of polymers, biology, materials science, and physical chemistry are briefly reviewed. The main strategies of development of small-angle neutron scattering on pulsed sources are considered. The possibilities of the small-angle instruments based on a synchrotron source and on a neutron pulsed source are compared.

Neutron Study of Internal Stress in Materials and Components

The development and current state of instrumentation for the neutron diffraction study of internal stresses has been considered. During the last 15 years, significant progress has been achieved in the experimental techniques based on stationary and pulsed neutron sources. Specialized stress diffractometers have been developed, which make it possible to solve many engineering and technological problems, as well as problems of fundamental materials science. Two Russian neutron stress diffractometers are considered: FSD on the pulsed reactor IBR-2 at the Joint Institute for Nuclear Research and STRESS on the IR-8 reactor at the Natioanl Research Centre “Kurchatov Institute.” Examples of studies performed on these devices are presented.

Trace elements risk assessment for consumption of wild mussels along South Africa coastline

The study aimed to contribute to the scarce data on concentrations in the soft tissue of wild mussels growing in coastal cities of South Africa. The intake of 26 micro and macroelements was estimated. The mass fractions of sample sets from 8 sites along the South African coast from the West (Port Nolloth) to the East (Durban) were studied by neutron activation analysis at the Joint Institute for Nuclear Research (Russia). The following elements were identified as potentially hazardous due to high consumption risks: Al, Cr, Co, Zn, As, and I at stations in the Cape Town area (Waterfront, Hout Bay) and Durban. The mean concentrations of these elements among all individuals were 208, 0.8, 0.46, 60, 2.6, and 11 ppm of wet weight, respectively. In the studied mussels, the concentrations of Cr, Zn, As, and Se (ranging between 0.2−2.8, 14–290, 1.6−4.6, and 0.31−2.4 ppm of wet weight, respectively) exceeded maximum permissible levels for fish products. The weekly consumption of more than 250 g of fresh mussels per person could increase the risk for human health by potential intake of such elements as Al, As, and I.

БАЗОВЫЕ РЕГИОНАЛЬНЫЕ НАУЧНЫЕ КЛАСТЕРЫ РОССИИ

The paper analyzes the scientific activity of Russian organizations in the three regional scientific clusters of Russia (Moscow, St. Petersburg and the cluster of the Moscow region), the results of which in a number of branches of science are characterized by high values of the demand, citation and Hirsch indices obtained on the basis of scientometric indicators (publication activity, citation, Hirsch index) from the database of the Russian Science Citation Index (RSCI). At the same time, 11 such natural science branches were identified in the Moscow cluster (chemical technologies and industry, geodesy and cartography, biology, physics, communications, chemistry, biotechnology, astronomy, electrical engineering, electronics and radio engineering, geography) and corresponding organizations in each of these branches of science, in St. Petersburg-six (electrical engineering, physics, geology, electronics and radio engineering, geodesy and cartography, mechanics), in the Moscow region cluster – five (physics, instrumentation, chemistry, chemical technologies and industry, nuclear engineering). The three leaders in the index of demand for research results in the Moscow cluster include the L.Y. Karpov Research Institute of Physics and Chemistry (branch of science – chemical technologies and industry), the Research and Design Institute of Information, Automation and Communication in Railway Transport (geodesy and cartography) and the Institute of Micro-Production (biology). The Moscow Region cluster is dominated by the Institute of Microelectronics Technology and High-Purity Materials of the Russian Academy of Sciences (physics), the Joint Institute for Nuclear Research (instrumentation) and the Institute of Engineering Immunology (chemistry). Among the leaders in the St. Petersburg cluster are the M.A. Bonch-Bruevich St. Petersburg State University of Telecommunications (electrical engineering), Peter the Great St. Petersburg Polytechnic University (physics) and I.S. Gramberg Research Institute of Geology and Mineral Resources of the World Ocean (geology).

Опыт подготовки студентов и аспирантов наукоемких технологий в наукоградах России

We analyze the domestic experience of training students and Post-Graduates of high technologies on the example of the leading universities of science cities of Russia: Biysk Technological Institute (branch of the Polzunov Altai State Technical University) (Biysk), Joint Institute for Nuclear Research (Dubna), Obninsk Institute for Nuclear Power Engineering – branch of National Research Nuclear University “MEPhI” (Obninsk), Pushchino State Natural Science Institute (Pushchino). We consider educational programs, the main directions of research activity, interac-tion with enterprises, Research Institutes, Scientific Production Centers, interaction technologies. As a result, conceptual approaches to the successful development of the leading universities of science cities in Russia are identified: support for new companies (“startups”) the founders of which are usually enterprises, research institutes or universities; promotion of entrepreneurial in-dependence of students and employees of higher educational institutions and research institutions; integration of large and small technology companies into innovative clusters; conducting student internships and performing research work in the laboratories of science cities; assistance from state, regional and local authorities, grant assistance.

TANGRA multidetector systems for investigation of neutron-nuclear reactions at the JINR Frank Laboratory of Neutron Physics

In the framework of TANGRA-project at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear research in Dubna (Russia), two experimental setups (Fig. 1) have been designed and tested for investigation of 14-MeV neutron-induced nuclear reactions on a number of important for nuclear science and engineering isotopes. As a source of 14-MeV “tagged” neutrons we are using the VNIIA ING-27 steady-state portable neutron generator with embedded in its vacuum tube 64-pixel charge-particle detector. The “Romashka” system is an array of up-to 24 hexagonal NaI(Tl)-crystal scintillation probes, while the “Romasha” array consists of 18 cylindrical BGO-crystal detectors of neutrons and gamma-rays. In addition to these detectors there is a HPGe gamma-ray spectrometer and a number of Stilbene detectors that can be added for high-resolution gamma-ray spectrometry and neutron-gamma detection. The main characteristics of the neutron-induced nuclear reaction products can be investigated by commissioning the detectors in suitable for these experiments’ geometries. Both setups can be used for doing basic and applied scientific research, because they permit simultaneously to measure the energy, angle and multiplicity distributions of gamma-rays and neutrons, produced in the competitive neutron-induced nuclear reactions (n, n’γ), (n,2n), (n, xnγ) and (n, f) in pure or complex substances.

Data Acquisition System Prototype of the ITER Diagnostic Divertor Neutron Flux Monitor Testing at Research Nuclear Facilities

The Divertor nuclear flux monitor (DNFM) is one of the ITER neutron diagnostics. This diagnostic consists of the three same subsystems. Each subsystem concludes the detector module with fission chambers (FCs) and the data acquisition system (DAQ). To solve the task of the neutron flux measurements in the range of 7 orders of magnitude and 1 ms of time resolution the multidetector module is used. To confirm the possibility of the neutron flux measurements in a wide range using such a detector module and to evaluate the characteristics of the DAQ prototype a number of tests were carried out under conditions of the intense neutron radiation. The detector module and the DAQ, which are the prototype of the equipment planned for use on site were used for the tests. The tests were carried out at the plasma neutron diagnostic stand based on the NG-24M neutron generator and at the IBR-2 pulsed reactor of the Joint Institute for Nuclear Research. During the tests at the plasma neutron diagnostic stand the data for the calibration of the DNFM DAQ measuring channels were collected. During the tests at the IBR-2 pulsed reactor the signals from the measuring channels of the DNFM subsystem were obtained while the neutron flux was changed. This report shows the test results and the subsystem calibration techniques.

Heat transfer of hexagonal boron nitride (h-BN) compound up to 1 MeV neutron energy: Kinetics of the release of wigner energy

In the present work, hexagonal boron nitride (h-BN) samples were irradiated by using high fluxes neutron irradiation. The neutron irradiation of the samples was carried out at the room temperature up to 1015 n/cm2 neutron flux with up to 1 MeV neutron energy at the IBR-2 M pulsed reactor in the Joint Institute for Nuclear Research, Dubna, Russia. The hexagonal boron nitride (h-BN) heat transfers changes with a differential mechanism under high flux neutron irradiation. The heat transfer depends on the transfer energy of the neutron. In the DSC curves for unirradiated and irradiated hexagonal boron nitride samples are seen phase transitions at the high temperature. However, the mechanism of the heat transfer flow rate functions for hexagonal boron nitride is more complex at the 300 ≤ T ≤ 1400 K temperature range. On the other hand, the Wigner energy of irradiated boron nitride samples was calculated for each of the irradiation fluxes. The Wigner energy increased up to 373 J/g with increasing neutron flux. The results have revealed that it has been observed a change in the rate of release of Wigner energy from 400 K to 1300 K. The surface morphology of hexagonal boron nitride under different fast neutron irradiation doses is investigated. The swelling was observed in the surface dynamics of the materials with an increased dose of irradiation.

The MPD Experiment and JINR: construction status and physics performance

The Multi-Purpose Detector is under construction at the Joint Institute for Nuclear Research, as part of the NICA Accelerator Complex. It aims to study the phase diagram of QCD matter at maximum baryonic density, determine the nature of the phase transition between the deconfined and hadronic matter and search for the critical point. The current status of the production of MPD subdetectors will be reported on, as well as progress in preparations of the software and computing infrastructure.The general characteristis of the designed physics performance of the detector components will be discussed. Potential for the measurement of the spectra of identified hadrons, including hyperons and hypernuclei, as well as directed and elliptic flow determination will be discussed. Characteristis needed for the event-by-event fluctuations and femtoscopic measurements will be given. Electromagnetic calorimeter working in conjunction with the tracking system for the di-lepton measurements will be described. In summary, all the main components of the physics program of the MPD Collaboration will be enumerated.

Design and relative calibration of a beam profile measurement system for the SC200 superconducting cyclotron

The SC200 superconducting cyclotron promoted by the ASIPP (Hefei, China) and the Joint Institute for Nuclear Research (Dubna, Russia) has made significant progress. A new beam profile measurement system (BPMS) has been developed to operate inside the cyclotron to acquire information of the transverse beam profile. We present the structural layout of the BPMS in frame of the SC200 superconducting cyclotron operating scenario with many details, e.g. high magnetic field, compact structure, high radio frequency interference and strong irradiation, etc. The influences of the magnetic field, heat-dissipating method, and other factors on the BPMS were described in detail and solved. The energy loss, spectral matching, and the temperature dependency of the scintillation screen, as well as the directional characteristic of the imaging system were all taken into account for a relative calibration of the BPMS. The BPMS was adopted for beam diagnosis during the initial commissioning phase of the SC200, and the experimental results of light output and horizontal beam sizes were calibrated to provide quantitative information. Furthermore, the beam loss and vertical distribution of the beam were calculated, which provide important basis for beam tuning and optimization of the cyclotron. The successful application of the BPMS inside the compact cyclotron is of great significance for further shimming and optimization of the isochronous field.

Prospects for the study of the strangeness production within the PHQMD model

Strangeness and hypernuclei production in heavy-ion collisions is presently under active experimental and theoretical investigation and is of particular interest for the experiments at the new acceleration complex NICA (Nuclotron-based Ion Collider fAcility) which is under construction at the Joint Institute for Nuclear Research (Dubna, Russia). We study the production of (hyper)nuclei in the NICA energy range using a novel n-body dynamical transport approach called Parton-Hadron-Quantum-Molecular Dynamics (PHQMD).

Soft photon study at NICA’s facilities

For over three decades there has been no comprehensive understanding of the mechanism of soft photon (energy smaller than 50 MeV) formation. Experimental data indicate an excess of their yield in hadron and nuclear interactions in comparison with calculations performed theoretically. In JINR, in connection with the building of a new accelerator complex NICA, it has become possible to carry out such studies in pp, pA and AA interactions at energies up to 25 A GeV. We prepared the extensive physical program for soft photons that covers the wide region of investigations in high energy physics. To carry out this program our group develops the conception of an electromagnetic calorimeter on type “shashlik” based on gadolinium-gallium garnet (GaGG) crystals, which have a significantly lower threshold for the registration of photons. The first tests of electromagnetic calorimeters manufactured at the Joint Institute for Nuclear Research on the basis of the GaGG crystals and a composite of tungsten and copper are reported.

Calculating the Linear Energy Transfer Distribution in Radiobiological Experiments on the U400M Cyclotron

Radiobiological experiments with the irradiation of various biological samples by nuclei from boron to neon with a primary energy of 30–50 MeV/nucleon are performed on the U400M cyclotron of the Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research. The linear energy transfer (LET) of the nuclei in samples is calculated using the code Lise++. For reducing the energy of nuclei and increasing their LET, aluminum filters with different thickness are placed before samples. The presence of filters and other absorbers before a sample results in the production of secondary charged particles whose LET may strongly differ from the LET of primary nuclei of the beam. This also affects the accuracy of calculating the absorbed dose. For this reason, detailed calculations of particle fields in samples are performed using the Monte Carlo code for radiation transport in matter PHITS 3.20 for several variants of sample irradiation with thick absorbers before samples. The calculated LET distributions are analyzed and compared with the calculations using the code Lise++.

Preface

The VI International Conference LaPlas-2020 A.P. Kuznetsov and S.V. GenisaretskayaVI Conference on Plasma and Laser Research and Technologies took place on February 11 until February 14, 2020 at the National Research Nuclear University “MEPhI”. The Conference was organized by the Institute for Laser and Plasma Technologies and was supported by the Competitiveness Program of the National Research Nuclear University “MEPhI”. The conference is based on scientific fields as follows: □ Laser, plasma and radiation technologies in industry, power engineering and medicine;□ Photonics, quantum metrology, optical information processing;□ New functional materials, metamaterials, “smart” alloys and quantum systems;□ Superstrong optical fields, powerful lasers, Mega Science installations;□ Applied mathematics and mathematical modeling□ High energy density physics;□ Physics of high-temperature plasma, environmentally safe energy on the basis of controlled thermonuclear synthesis;□ Spectroscopic synchrotron, neutron, laser research methods, quantum-mechanical calculations and computer simulation of condensed media and nanostructures; The conference consisted of nine sections: □ Laser physics and laser technology□ Plasma physics and controlled thermonuclear fusion□ Modern problems of theoretical physics□ Applied mathematics and mathematical modelling□ Modern problems of solid state physics, functional materials and nanosystems□ Modern problems of measuring systems and quantum metrology□ Accelerators of charged particles and radiation technology□ Electrophysical and nuclear instrumentation□ High energy density physicsMore than 300 specialists took part in the Conference. They represented leading Russian scientific research centers and universities (National Research Centre “Kurchatov Institute”, P.N. Lebedev Physical Institute, A.M. Prokhorov General Physics Institute, Joint Institute for Nuclear Research, Moscow Institute of Physics and Tecnology and others) and leading scientific centers and universities from Germany, Italy, France, Canada, Japan.We would like to thank heartily all of the speakers, participants, organizing and program committee members for their contribution to the conference.

Feasibility and physics potential of detecting 8B solar neutrinos at JUNO * *This work was supported by the Chinese Academy of Sciences, the National Key R&D Program of China, the CAS Center for Excellence in Particle Physics, the Joint Large-Scale Scientific Facility Funds of the NSFC and CAS, Wuyi University, and the Tsung-Dao Lee Institute of Shanghai Jiao Tong University

The Jiangmen Underground Neutrino Observatory (JUNO) features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector. Some of JUNO's features make it an excellent location for B solar neutrino measurements, such as its low-energy threshold, high energy resolution compared with water Cherenkov detectors, and much larger target mass compared with previous liquid scintillator detectors. In this paper, we present a comprehensive assessment of JUNO's potential for detecting B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2 MeV threshold for the recoil electron energy is found to be achievable, assuming that the intrinsic radioactive background U and Th in the liquid scintillator can be controlled to 10 g/g. With ten years of data acquisition, approximately 60,000 signal and 30,000 background events are expected. This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter, which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework. If eV , JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3 (2 ) level by measuring the non-zero signal rate variation with respect to the solar zenith angle. Moreover, JUNO can simultaneously measure using B solar neutrinos to a precision of 20% or better, depending on the central value, and to sub-percent precision using reactor antineutrinos. A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of reported by solar neutrino experiments and the KamLAND experiment.

\(Z_0(57)\) and \(E(38)\): Possible Surprises in the Standard Model

With the reported observation of the Higgs boson at the LHC, the Standard Model of particle physics seems to be complete now as for its particle content. However, several experimental data at low and intermediate energies indicate that there may be two surprises. First we propose a tentative new boson $Z_0(57)$, with a mass of about 57 GeV, on the basis of small enhancements we observe in several experiments, using recent data obtained at the LHC as well as much older ones from LEP. If confirmed, we interpret this new particle as a pseudoscalar or scalar partner of a composite $Z$ vector boson. Secondly, we advocate the existence of a very light spinless boson $E(38)$, probably a scalar, with a mass of 38 MeV and decaying into two photons. Theoretical arguments and experimental signals supporting such a novel light boson will be presented, including a recent direct experimental confirmation at the Joint Institute for Nuclear Research in Dubna.

Comparing atmospheric trace element accumulation of three moss species

Introduction: The intention of Vietnam to participate in the European-Asian Moss Survey in the framework of The United Nations Economic Commission for Europe - International Cooperative Programme on effects of air pollution on natural vegetation and crops (UNECE ICP Vegetation) necessitates choosing appropriate moss species that grow in the tropical and subtropical climate of Vietnam. The three selected moss species, divided into phytogeographical elements, were as follows: Leucobryum (aduncum, albidum), Hypnum commutatum and Barbula indica.
 Methods: The present study focuses on Central Vietnam where 18 samples of the three above moss species were collected in the vicinity of Dalat and Hue cities. Elements in the moss samples were detected by neutron activation analysis (NAA) at the IBR-2 reactor of the Division of Neutron Activation Analysis, Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research in Dubna, Russia.
 Results: The analytical results for twenty-three trace elements, which were used to study elemental accumulation abilities of the three moss species in the air, were Na, Mg, Al, Cl, K, Ca, Ti, V, Mn, Fe, Co, Zn, As, Br, Rb, Sr, Sb, I, Cs, Ba, La, Th, and U. The accumulation abilities were found to decrease in the following order: Leucobryum > Hypnum > Barbula. However, Leucobryum, because of its short stem, was not judged to be a suitable candidate for biomonitoring.
 Conclusion: The element accumulation abilities of Hypnum moss were better than those for Barbula, but both were comparable and could be used as indicators for air deposition monitoring; however, Hypnum was not widely present in Vietnam. Thus, Barbula indica moss could be used for performance of atmospheric deposition monitoring in Vietnam.

Collaboration with JINR as Key for Nuclear Physics Development in Ukraine

Introduction. Today, the Joint Institute for Nuclear Research (JINR) is a kind of scientific and technical framework for Ukrainian nuclear researchers who are directly involved in conducting the cutting-edge nuclear physics experiments. Problem Statement. An important aspect of international cooperation for the Ukrainian researchers in the field of nuclear physics and materials science is to consolidate scholarly research, engineering, and financial resources of countries for creating international research organizations and implementing large-scale projects in modern science and technology. Purpose. Analysis of the factors that contribute to the development of nuclear physics and research in related disciplines in Ukraine, involvement of Ukrainian researchers in international research processes, and assessment of the future prospects. Materials and Methods. Analysis of scholarly research trends in the Joint Institute for Nuclear Research (JINR) and review of achievements of Ukrainian researchers, in particular, young researchers, in implementation of international projects in nuclear physics and related disciplines. Results. The background of nuclear physics research in Ukraine, the way of international cooperation development, and its impact on education and training of researchers have been analyzed. The examples of research results of Ukrainian nuclear physicists have been given. The cooperation of Ukrainian R&D organizations and companies with JINR has been shown to have a positive effect on creative and innovative processes, including the development and study of new high-tech materials. Conclusions. Collaboration with JINR gives Ukrainian researchers access to modern methods of physical research and unique equipment at leading international R&D centers, while planning and implementing large-scale experiments in nuclear physics, and enables studying the problems of the Universe. Teachers, students, and schoolchildren from Ukraine have additional opportunities to work with the cutting-edge methods, modern equipment and innovative approaches in the field of science and technology.