Frank Laboratory Of Neutron Physics Research Articles

Pneumatic Transport System REGATA-2 for Automation of Activation Analysis at the IREN Facility, FLNP JINR

The IREN facility at the Frank Laboratory of Neutron Physics (FLNP) of the Joint Institute for Nuclear Research (JINR) is used for experiments to determine elemental composition of various samples by neutron activation analysis (NAA). A pneumatic transport system (PTS) REGATA-2 was implemented to automate the delivery of containers with samples to the irradiation position and back. The article describes the characteristics of the PTS, its adaptation for operation at the IREN facility, and also plans for subsequent modernization and future prospects. After the assembling of the system, the optimal parameters were chosen for irradiating the typical samples, and a calibration was created for a high-purity germanium detector, which let to consider the volume nature of the samples. Samples of archaeological ceramics from Kazakhstan were studied using the PTS. The features of the IREN facility let to use not only a neutron, but also a gamma-producing target. The first experiments on the qualitative determination of elements by gamma-activation analysis (GAA) were carried out, and the prospects for using the facility for these purposes were confirmed. The creation of the PTS let to automate the process of irradiation samples and increase the efficiency of research in NAA and GAA, especially for short-lived isotopes. It also reduces the negative impact of radiation on the human body.

Optimization of the cold moderator for the new pulsed reactor NEPTUN

The Frank Laboratory of Neutron Physics (FLNP) at the Joint Institute for Nuclear Research (JINR) has begun designing a new research reactor, NEPTUN, to replace the IBR-2M (pulsed fast reactor - the name in russian) reactor, which is expected to be out of service between 2032 and 2036. The IBR-2 reactor is a third-generation neutron source that started working in 1982 at Dubna, Russian Federation. The IBR-2M reactor was successfully modernized in 2012. The NEPTUN reactor is a fourth-generation neutron source that will use Np-237 as a nuclear fuel for the first time. It was studied if mesitylene (1,3,5-trimethylbenzene), which is now being utilized effectively in the reactor IBR-2M, might be used as a cold moderator in the new research reactor NEPTUN with an average thermal power of 15 MWt. A study of five materials used as a cold neutron moderator at various temperatures was also conducted. Longer working times for cold moderator material were another goal of optimization. According to the findings, mesitylene at a temperature of 20 K should be used as a cold moderator to get the greatest neutron flux at a wavelength of 3 ≤ λ ≤ 10 Å. Additionally, ortho hydrogen at 20 K could increases the cold neutron flux with wavelengths, λ ˃ 10 Å.

Cross sections of the Zr91(n,α)Sr88 reaction in the 3.9–5.3 MeV neutron energy region

Cross sections of the $^{91}\mathrm{Zr}(n,\ensuremath{\alpha})^{88}\mathrm{Sr}$ reaction were measured at four incident neutron energies in the range of 3.9 to 5.3 MeV. The experiment was carried out on the Van de Graaff accelerator EG-5 at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Russia. Fast neutrons were produced via the $^{2}\mathrm{H}(d,n)^{3}\mathrm{He}$ reaction with a deuterium gas target. A twin gridded ionization chamber (GIC) was used as the charged particle detector, in which $^{91}\mathrm{Zr}$ back-to-back samples on a tantalum backing were placed at the common cathode. The relative and absolute neutron fluxes were measured using two $^{238}\mathrm{U}_{3}{\mathrm{O}}_{8}$ samples inside the GIC. Cross-section data obtained in this measurement were compared with those in existing data library and from theoretical calculations using talys code. The present data for the $^{91}\mathrm{Zr}(n,\ensuremath{\alpha})^{88}\mathrm{Sr}$ reaction should be helpful in clarifying the discrepancies in various published nuclear evaluation data. An alpha clustering factor is calculated using the statistical model and knock-on mechanism.

Non-destructive investigation of the Kyathos (6th-4th centuries BCE) from the necropolis Volna 1 on the Taman Peninsula by neutron resonance capture and X-ray fluorescence analysis

<p>The method of Neutron Resonance Capture Analysis (NRCA) is currently being developed at the Frank Laboratory of Neutron Physics. The Analysis determines the elemental and isotope compositions of objects non-destructively, which makes it suitable measurement tools for artefacts without sampling. NRCA is based on the registration of neutron resonances in radiative capture and the measurement of the yield of reaction products in these resonances.<br />The potential of NRCA at the Intense Resonance Neutron Source facility is demonstrated on the investigation of a Kyathos (6th-4th centuries BCE) from the necropolis Volna 1 on the Taman Peninsula. In addition, X-ray analysis was applied to the same archeological object. The element composition determined by NRCA and XRF data is in agreement.</p>

Удаан нейтроноор цэнэгт бөөм үүсэх урвалын астрофизикийн хэрэглээ

Results of statistical model calculations for average (n,a) cross sections arc compared with experimental values at E=30 keV. Using the results of theoretical calculations for the (n,a) and (n,p) cross sections were proposed new measurement for nuclear astrophysics study on the IREN neutron source projected at the Frank Laboratory of Neutron Physics, JINR, Dubna.

The features of heavy metals and metalloids accumulation in the phytomass of the amphipodous moss <i>Pleurozium schreberi</i> (Brid.) Mitt. in the conditions of the Krasnosamarsky Forest area (Samara Region) and the National Park «Buzuluksky Bor» (Orenburg Region)

The paper analyzes ecological and geochemical features of the moss Pleurozium schreberi (Brid.) Mitt., growing in artificial pine plantings of the National Park Buzuluksky Bor (Orenburg Region) and the Krasnosamarsky Forest (Samara Region). The research has been carried out within the framework of the International Program ICP Vegetation (https://icpvegetation.ceh.ac.uk), on the practical use of some bryophyte species in the environmental monitoring of multi-element air pollution in the countries of Western and Eastern Europe and a number of other countries. In the National Park Buzuluksky Bor and the Krasnosamarsky Forest, where species diversity and ecological characteristics of bryophytes have been studied for several years, the phytomass of the moss Pleurozium schreberi has been selected. This species is included in the species list proposed by the organizers of the research work under the UNECE ICP Vegetation Program. A multi-element analysis of Pleurozium schreberi phytomass has been carried out on the basis of the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research in Dubna using instrumental epithermal neutron activation analysis (ENAA). The biogeochemical similarity of the moss Pleurozium schreberi from the Krasnosamarsky Forest and Buzuluksky Bor, estimated by the concentration coefficients, has manifested itself in relation to a large group of heavy metals and metalloids, characterized by a relatively low ability to accumulate in its phytomass (Ti, V, Cr, Fe, Co, As, Se, Rb, Sr, Mo, Cd). Some differences have been revealed in relation to the elements with the maximum accumulation: Cu and Zn in the Krasnosamarsky Forest area, Mn and Ni - in the Buzuluksky Bor. A relatively low content of most of the analyzed heavy metals and metalloids in the soil of the studied territories as well as in the phytomass of the biomonitor moss Pleurozium schreberi allows us to consider them to be background for the steppe zone of the European part of the Russian Federation.

Application of non-destructive neutron resonance capture analysis for investigation of women’s Old Believer cross dating back to the second half of the 17th century

Neutron Resonance Capture Analysis (NRCA) is presently being developed at the Frank Laboratory of Neutron Physics (FLNP) to determine the elemental composition of samples. The NRCA is a nondestructive method that allows measuring objects’ bulk composition. The procedure is based on detecting neutron resonances in radiative capture and the measurement of the yield of reaction products in these resonances. The experiments are carried out at the Intense REsonance Neutron source (IREN). In this study, we applied the NRCA to investigate an archaeological object provided by the Museum and Exhibition Complex (MVK) "Volokolamsk Kremlin". The object was a women’s Old Believer cross (second half of the 17th century) found in the Moscow region, Volokolamsk district, the village of Chubarovo.

The anisotropic properties of granites – effects of tectonic emplacement mode on potential crystalline host rocks for nuclear waste deposits in Germany

Abstract. For permanent nuclear waste disposal sites, crystalline rocks, especially granitic/granodioritic batholiths, are considered an appropriate host rock. Principally, three types of granitic plutons occur in the extra-alpine crystalline basement of Germany that were consolidated during the late Paleozoic Variscan orogeny of Central Europe: (i) Pre-Variscan voluminous granodiorites that are hardly affected by the subsequent continent–continent collision; (ii) voluminous granites in various tectonic settings intruded during the late orogenic stage of the Variscides; (iii) post-orogenic granites related to vast Permian intracontinental extension. Thus, in terms of the syn-intrusive tectonic setting and post-intrusive processes there are significant differences. Although it can be expected that different tectonic environments caused significant differences in the material properties, for Germany, however, there is no systematic study regarding the fabric of such plutonites. In order to find the most suitable “granite” we investigate the primary anisotropy of granites evolved during the emplacement and crystallization of the melt. For this we sample rocks of all three principal types and various syn-intrusive tectonic settings, i.e., compression, extension, strike-slip, transtension, and transpression. By means of combined measurements of the “Anisotropy of the Magnetic Susceptibility” and the “Shape Preferred Orientation” we characterize the syn-intrusive flow pattern, i.e., the magmatic foliation and lineation. The Crystallographic Preferred Orientation is analyzed by a combination of neutron time-of-flight experiments and electron backscatter diffraction measurements at the Frank Laboratory of Neutron Physics at JINR, Dubna, Russia, and the TU Bergakademie Freiberg respectively. Furthermore, special attention is given to the systematic mapping of annealed microcracks evolved during late magmatic fluid escape and/or post-crystallization hydrothermal activity. In a second step we compare the primary anisotropy with the post-magmatic fracture pattern of the particular granites. Those fractures constitute probable fluid pathways and, thus, the first-order risk for a potential permanent nuclear waste disposal. All datasets are organized in a Geological Information System allowing for a complete traceability of the different investigation steps. The results of this study will serve as a basis for a future detailed exploration.

Cross sections for the Cl35(n,α)P32 reaction in the 3.3–5.3 MeV neutron energy region

Cross sections for the $^{35}\mathrm{Cl}(n,\ensuremath{\alpha})\phantom{\rule{0.16em}{0ex}}^{32}\mathrm{P}$ reaction were systematically measured at incident neutron energies in the range of 3.3 to 5.3 MeV. The experiment was carried out on the Van de Graaff accelerator EG-5 at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Russia. Fast neutrons were produced in the reaction $^{2}\mathrm{H}(d,n){\phantom{\rule{0.16em}{0ex}}}^{3}\text{He}$. Alpha particles from the ($n,\ensuremath{\alpha}$) reactions were detected using a gridded ionization chamber (GIC) in which various $^{35}\mathrm{Cl}$ samples (NaCl and ${\text{BaCl}}_{2}$, on a tantalum backing) were placed back to back. The relative and absolute neutron fluxes were measured by two samples of $^{238}\mathrm{U}_{3}\mathrm{O}_{8}$ ($99.999%$) inside the GIC. Data obtained in this measurement were compared with other experimental data of the existing library and theoretical calculations by the talys code. Presented data for the $^{35}\mathrm{Cl}(n,\ensuremath{\alpha})\phantom{\rule{0.16em}{0ex}}^{32}\mathrm{P}$ reaction should help to clarify discrepancies in the various published nuclear data.

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.

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.

Elemental Analysis of the Molding Paste of Medieval Oriental Faiences

This publication is devoted to the analysis of ceramic items found in Bolgar, the capital of Volga Bulgaria (now it is the territory of Tatarstan, Russia). Neutron activation analysis (NAA) and X-ray fluorescence (XRF) analysis of the ceramic paste of glazed medieval stonepaste ceramics (fritware) was carried out by the NAA group at the IREN facility of the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research. The batch was transferred from the Institute of Archeology of the Russian Academy of Sciences and included 13 samples. For the first time, the task was to comparatively study stonepaste of wares produced in different countries of the East. The results were compared with data on similar ceramics previously published by other researchers.

Analysis of Focusing Properties of the Edge Electric Field of the Accelerating Structure of the Lue-200 Accelerator

The electric component of the RF field at the input of the traveling wave accelerating structure (operating frequency of 2856 MHz) of the LUE-200 linear electron accelerator – a driver for the pulsed source of the IREN facility developed at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research (Dubna, Russia) – is considered. The estimates of the focusing effect of the RF field on the nonrelativistic electron beam injected into the structure after the buncher performed for the thin electric lens model have shown that the focusing effect of the edge RF field for the beam particles turns out to be sufficiently rigid.

Instrument Control Software at the IBR-2 Reactor: Features and Prospects

The Sonix package is the main instrument control software at the IBR-2 reactor. It was originated in the beginning of 1990s for the Neutron Spectrometer with High Resolution (beam 6A of IBR-2). Later the complex was transferred to other instruments, including those located outside Frank Laboratory of Neutron Physics. A little bit less than 20 installations are in operation now. When developing the complex, we were guided both by world trends, as well as by the specifics of our laboratory. Many important requirements were formulated by our users, therefore, they can be considered as real co-authors of the project. Besides an instrument control itself, the complex also includes remote measurement supervising subsystem (WebSonix service) and the central repository for measurement results.

Vertical Distribution of Major and Trace Elements in a Soil Profile from the Nile Delta, Egypt

Abstract The present study was conducted to highlight the elemental composition of ten soil samples collected at different depths along of a soil profile (0.25-17 m). The collected samples were subjected to epithermal neutron activation analysis at the pulsed reactor IBR-2 of Frank Laboratory of Neutron Physics - Joint Institute for Nuclear Research - Dubna - Russian Federation. The concentrations in mg/kg of 36 major and trace elements were determined. Symbatic behaviour of geochemically related elements was observed: Th and U; Cl and Br and Fe, Ti, Ca, Al, and Mg, etc. A sharp increase of certain concentrations at the depth of 8 m was observed. Significant mafic sources of elements were observed and mostly are attributed to Ethiopian High Plateau with small amount of felsic volcanic rocks.

Determining the Elemental Composition of Antique Coins of Phanagorian Treasure by Neutron Spectroscopy at the Pulsed Neutron Source IREN in FLNP JINR

Abstract—Neutron Resonance Capture Analysis (NRCA) is currently being developed in the Frank Laboratory of Neutron Physics (FLNP) for the purpose of determining the element composition of samples. This method is based on registering neutron resonances in radiative capture and measuring the yield of reaction products in these resonances. To test the capabilities of this method, such investigations have been carried out in collaboration with the Institute of Archaeology of the Russian Academy of Sciences at the IREN pulsed neutron source, FLNP, for ancient coins from Phanagorian treasure. A cylindrical multisectional liquid scintillator detector is used to detect γ-quanta.

Measurement of the Yield and Angular Distributions of Gamma Rays Originating from the Interaction of 14.1-MeV Neutrons with Chromium Nuclei

The reaction induced by the inelastic scattering of 14.1-MeV neutrons on chromium nuclei is studied by means of the tagged-neutron method at the TANGRA (TAgged Neutrons and Gamma RAys) facility deployed at Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, and based on the ING-27 standard neutron generator. The energies of visible gamma transitions occurring in various reactions of neutron interaction with chromium nuclei and their partial cross sections are determined. The results obtained by measuring the angular distribution of gamma rays for $${}^{52}$$ Cr are analyzed and are compared with respective results of other experimental studies available in the literature.

Cryostat for cooling samples in the study of low-temperature structural and magnetic phase transitions by neutron diffraction

A vertical cryostat was developed built around a Sumitomo RDK-101D cold head. The cryostat is intended for investigating the structure and phase transformations of different materials via neutron diffraction experiments on samples under high vacuum of up to 10−5 mbar. A working temperature of the sample close to 2 K was reached. The drift diameter of the head is 54 mm, making it possible to cool samples with a height of 55 mm and 15 mm in diameter. Test measurements were conducted and illustrative spectra were recorded on the example of a sample of HoFeO3. The cryostat was designed and manufactured at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research.

Measurements of neutron-induced light-charged particle emission reactions

In the past two decades cooperating with Frank Laboratory of Neutron Physics (FLNP), Joint Institute for Nuclear Research (JINR) measurements of (n, α) reaction cross sections for 6Li, 10B, 25Mg, 39K, 40Ca, 54,56,57 Fe, 58Ni, 63Cu, 64,67 Zn, 95Mo, 143Nd and 147,149 Sm nuclei were performed in the MeV neutron energy region based on the 4.5 MV Van de Graaff accelerator at Peking University. In recent years, our measurements were extended in three aspects. Firstly, measurements were expanded from two-body reactions to three-body reactions such as 10B (n, t2 α). Secondly, the neutron energy region was extended from below 8 MeV to 8 - 11 MeV by using the HI-13 tandem accelerator of China Institute of Atomic Energy (CIAE), with which cross sections of 54,56 Fe(n, α)53,51Cr reactions were measured. Thirdly, based on the newly-built China Spallation Neutron Source (CSNS) Back-n WNS (White Neutron Source), differential and angle-integrated cross sections for 6Li(n, t) and 10B(n, α) reactions were measured in the neutron energy region from 1 eV to 3 MeV.

Investigation of 14.1 MeV neutrons interaction with C, Mg, Cr

This paper is dedicated to n+12C, n+24Mg, n+52Cr -reactions investigation at 14.1 MeV neutron energy. Characteristics of these reactions have been calculated using TALYS code to estimate perspectives of using of this code in data interpretation in the TANGRA project. This project is performed in Frank Laboratory of Neutron Physics (FLNP JINR) to investigate properties of (n,xγ)-type reactions, important for fundamental and practical applications.