IBR-2 Pulsed Reactor Research Articles

Possibilities of Studying Biological Objects on a Pulsed Reactor

Small-angle scattering makes it possible to solve structural biology problems without specific sample preparation, which is typical for methods such as X-ray diffraction of protein crystals or cryo-electron microscopy of proteins. In our review, it is shown how to use small-angle scattering to address biological problems. The use of small-angle scattering is suggested for applications as a tool to control the quality of the assembly of proteins and protein complexes and to test the identity of the structural organization of biological objects in the native state and in prepared samples before measurements by X-ray diffraction or cryo-electron microscopy. This work demonstrates the possibilities of the small-angle neutron scattering spectrometer YuMO based on the IBR-2 pulsed reactor (Laboratory of neutron physics, Joint Institute for Nuclear Research, Dubna, Russia) to solve a whole array of problems, with an eye toward applying these in biophysics, structural biology, and biotechnology. This review presents and discusses the main findings of the studies of various biological systems obtained by using the setup small-angle scattering of neutrons YuMO. The possibilities of development of structural biology methods with the help of small-angle scattering, including protein crystallization, are shown.

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

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

Wide-aperture back-scattering detector (BSD) for the High-Resolution Fourier Diffractometer (HRFD) at the IBR-2 reactor

The high-resolution Fourier diffractometer (HRFD) operates at the IBR-2 pulsed reactor, on which the correlation method of data registering has been implemented using a fast Fourier chopper and specialized electronics. A wide-aperture ring back-scattering detector for HRFD has been developed. The detector consists of six Z n S ( A g ) / 6 L i F-scintillation rings, each one of which is divided into 12 sections. Main parameters of this detector: covered solid angle 2 θ = ( 133 − 175 ) ∘ ; Ω d ≈ 2.0 sr; average absorption efficiency 85 %, geometric contribution to resolution Δ d / d < 0.0005. The concept of a detector and its data acquisition system are presented.

Neutron-diffraction study of the cubic-tetragonal phase structural transition in the single crystals of the solid solutions of zirconium and yttrium oxides

Objectives. The determination of the phase relations, crystallographic characteristics, microstructure features, and atomic crystal structure of zirconium oxide crystals that are partially and completely stabilized by yttrium oxide additives, and the identification of the crystallographic and crystal-chemical correlations with the physicochemical properties of single crystals.Methods. The neutron structure of the crystals was studied using the neutron time-of-flight and constant wavelength methods using a high-resolution Fourier diffractometer on the IBR-2 pulsed fast reactor and a four-circle neutron diffractometer “Syntex.” Single crystals were grown by directed crystallization from the melts of mixtures (1 − х)ZrO2 ∙хY2O3 , х = 0.03 and х = 0.12 with different growth rates (10 and 40 mm/h).Results. It was observed that when growing single crystals with x = 0.03–0.05, the crystal was stratified into cubic and tetragonal phases, and the ratio between the phases depended on the growth rate. At a growth rate of 40 mm/h, the content of the cubic phase was insignificant. In the crystals of partially stabilized zirconium dioxide (ZrO2) with the additions of 3 mol % Y2O3, the coherent coexistence of cubic and tetragonal phases was established, and the twin law for a tetragonal component (rotation of unit cell axis by 90° around the a (b) axis) that was observed during the phase transition from high-temperature cubic phase to tetragonal phase was determined. For the fully stabilized zirconium oxide of the cubic symmetry (with 12 mol % Y2O3), the 0.3 Å displacements of oxygen atoms from their partial structural positions in the directions [100] and [111] were determined. These displacements correlated with the directions of the ion transport.Conclusions. Previous studies have shown that the ratio between the cubic and tetragonal phases of the single crystals of the ZrO2 –Y2O3 system depends on the growth rate of the single crystals. The content of Y2O3 in the cubic and tetragonal phases of a single crystal was determined using the non-destructive neutronography method on the same volume sample of a solid solution of this system. Moreover, the displacements of oxygen atoms from the main position of the crystal were determined.

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.

High-Pressure Neutron Diffraction Study of the Crystal and Magnetic Structure of Materials at the Pulsed Reactor IBR-2: Current Opportunities and Prospects

The experimental capabilities and results of recent studies of the crystal and magnetic structure of functional materials on the diffractometers DN-12 and DN-6 of upgraded high-flux pulsed reactor IBR-2 in wide ranges of high pressures and temperatures are reviewed. The combination of high neutron flux on a sample, wide-aperture multidetector systems, and focusing devices has made it possible to implement diffraction experiments on samples with record-low volumes under ultrahigh pressures (up to 35 GPa) in the temperature range of 5–300 K. The results of recent studies of the structural and magnetic phase transitions in ferroelectrics, multiferroics, low-dimensional magnets, and other materials are presented.

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.

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.

Study of LiInSe2 Single Crystals for the Thermal Neutron Detection

Lithium–indium diselenide (LiInSe2) is a new semiconductor material, sensitive to the thermal neutrons. LiInSe2 compound was synthesized from Li (99.99%), In (99.999%) and Se (99.999%). The growth of LiInSe2 single crystals was performed using the vertical option of Bridgman–Stockbarger method. The crystals were characterized using the electrical conductivity and optical spectroscopy methods. Stoichiometric composition of the LiInSe2 was confirmed by the high precision chemical analysis, as well as by X-ray diffraction. Compact 252Cf neutron source with the activity 6.3 × 105 n/s allowed measuring amplitude characteristics and defining the optimal operating voltage for neutron detection. Time-of-flight neutron spectra were measured at the fast pulsed research reactor IBR-2 at the Joint Institute for Nuclear Research.

A Comparative Analysis of the Characteristics of Data Acquisition Systems From Position-Sensitive Neutron Detectors

Abstract—This article discusses the results of parallel measurements with two-coordinate position-sensitive He3 detectors with a delay line, which are installed on REFLEX and GRAINS neutron spectrometers of the IBR-2 pulsed reactor with the simultaneous use of three data acquisition systems: DeLiDAQ-1, DeLiDAQ-2, and a system based on the N6730 digitizer produced by CAEN.

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.

Low counting rate measurement on thermal neutron induced fission using cross-correlation technique

The measurement procedure based on the continuous thermal neutron beam modulation with a mechanical chopper was developed for delayed neutron yield measurement of the thermal neutron induced fission of [Formula: see text]Np. The idea of the procedure is similar to that widely used in modern computer communications to prevent unauthorized data access. The data is modulated with a predefined pattern before transmission to the public network, and only the recipient that has the modulation pattern is able to demodulate it upon receipt. For thermal neutron induced reaction applications, the thermal neutron beam modulation pattern was used to demodulate the measured delayed neutron intensity signals on the detector output, resulting in nonzero output only for the detector signals correlated with the beam modulation. The comparison of the method with the conventional measurement procedure was provided, and it was demonstrated that the cross-correlation procedure has special features making it superior to the conventional one, especially when the measured value is extremely small in comparison with the background. Due to the strong sensitivity of the measurement procedure on the modulation pattern of the neutron beam, one can implement the modulation pattern of a specific shape to separate the effect of the thermal part of the beam from the higher energy part in the most confident way in the particular experiment. The remarkable property of our method is related to the unique possibility of separation of the effects caused exclusively by thermal neutrons using the neutron time-of-flight measurement available on the IBR-2 pulsed reactor.

Thermal neutron intensity measurement with fission chamber in current, pulse and Campbell modes

In thermal nuclear reactors, most of the power is generated by thermal neutron induced fission. Therefore, fission chambers with targets that respond directly to slow neutrons are of great interest for thermal neutron flux measurements due to relatively low sensitivity to gamma radiation. However, the extreme conditions associated with experiments at very low cross section demand highly possible thermal neutron flux, leading often to substantial design changes. In this paper we report design of a fission chamber for wide range (from 10 to 1012 n/cm2 sec) measurement of thermal neutron flux. Test experiments were performed at the first beam of IBR2 pulsed reactor using digital pulse processing (DPP) technique with modern waveform digitizers (WFD). The neutron pulses detected by the fission chamber in each burst (5 Hz repetition rate) of the reactor were digitized and recorded to PC memory for further on-line and off-line analysis. New method is suggested to make link between the pulse counting, the current mode and the Campbell technique.

Investigation of dynamics of the IBR-2M pulsed reactor with energy-production up to 1200 MW·day

The operation of the IBR-2 pulsed reactor (1987-2006) showed that a total transfer coefficient of the power decreases during the operation of the reactor, therefore each reactor cycle has its own transfer coefficients [1] and stability margins. Hence, the study of dynamics of the new reactor IBR-2M (modernized version IBR-2, since 2011) is extremely important. In this paper, the results of an experimental and a modelling study of dynamics of the IBR-2M are presented, for the reliable and safe operation of reactor. For this purpose, model dynamics of the IBR-2M has been developed, which includes experimental data on reactor feedback parameters in period 2015-2017 at a mean power of 0.5 MW. Using the model dynamics of the IBR-2M, the stability margins of the reactor in different regimes its operation (self-regulating and automatic regulating) were estimated. It shown that during the analyzed time of the operation reactor with energy production up to 1200 MW·day significant changes in dynamics of reactor has not occurred. The reactor has been working in the stability region.

Light yield and radiation hardness studies of scintillator strips with a filler

Detectors based on polystyrene scintillator strips with WLS fiber readout are widely used to register charged particles in many high-energy physics experiments. The fibers are placed into grooves or holes along the strip. The detection efficiency of these devices can be significantly increased by improving the optical contact between the scintillator and the fiber by adding an optical filler into the groove/hole. This work is devoted to the study of the light yield of a 5-m-long scintillator strip with a 1.2-mm-diameter Kuraray Y11(200)~MC WLS fiber inserted into the strip's co-extruded hole filled with synthetic silicon resin SKTN-MED(E). The light yield was studied using cosmic muons and a $^{60}$Co radioactive source. Radiation hardness study of viscous fillers and short strip samples were performed on the IBR-2 pulsed research reactor of fast neutrons at JINR.

High-resolution neutron Fourier diffractometer at the IBR-2 pulsed reactor: A new concept

The High Resolution Fourier Diffractometer (HRFD) is a neutron time-of-flight spectrometer with a fast Fourier chopper and a correlation mode of data acquisition designed to study atomic and magnetic structures of crystalline materials with high resolution in reciprocal space. The HRFD was constructed in the early 1990s by a collaboration of JINR (Dubna), PNPI (Gatchina) and VTT (Espoo) and began operating routinely in 1994 at the IBR-2 pulsed reactor in Dubna. If correlation analysis is used, the HRFD Δd/d resolution is determined by the maximum rotational speed of the Fourier chopper. For Vmax = 6000 rpm, “high-resolution” patterns are measured by backscattering detectors with Δd/d ≈ 0.0015 despite a very short flight path (L ≈ 20 m) between chopper and sample. Switching to a regular TOF-mode (without Fourier chopper) makes HRFD one of the world’s best high-intensity diffractometers, capable of measuring diffraction patterns in the range of ∼1 min and less. In this paper, the experience of using HRFD at IBR-2 is considered and a possible solution for some technical and methodical problems of Fourier diffractometry at a long-pulse neutron source recognized during its operation is discussed. New possibilities appearing after the recent substantial HRFD upgrade and further perspectives on the method are also presented.

Neutron RTOF Stress Diffractometer FSD at the IBR-2 Pulsed Reactor

The diffraction of thermal neutrons is a powerful tool for investigations of residual stresses in various structural materials and bulk industrial products due to the non-destructive character of the method and high penetration depth of neutrons. Therefore, for conducting experiments in this research field, the neutron Fourier stress diffractometer FSD has been constructed at the IBR-2 pulsed reactor in FLNP JINR (Dubna, Russia). Using a special correlation technique at the long-pulse neutron source, a high resolution level of the instrument has been achieved (Δd/d ≈ 2 ÷ 4 × 10−3) over a wide range of interplanar spacing dhkl at a relatively short flight distance between the chopper and sample position (L = 5.55 m). The FSD design satisfies the requirements of a high luminosity, high resolution, and specific sample environment. In this paper, the current status of the FSD diffractometer is reported and examples of performed experiments are given.

Studies of electrochemical interfaces by TOF neutron reflectometry at the IBR-2 reactor

The operation performance of electrochemical energy conversion and storage systems such as supercapacitors and batteries depends on the processes occurring at the electrochemical interfaces, where charge separation and chemical reactions occur. Here, we report about the tests of the neutron reflectometry cells specially designed for operando studies of structural changes at the electrochemical interfaces between solid electrodes and liquid electrolytes. The cells are compatible with anhydrous electrolytes with organic solvents, which are employed today in all lithium ion batteries and most supercapacitors. The sensitivity of neutron reflectometry applied at the time-of-flight (TOF) reflectometer at the pulsed reactor IBR-2 is discussed regarding the effect of solid electrolyte interphase (SEI) formation on metal electrode surface.

Neutron Time-of-Flight Stress Diffractometry

Over recent decades, the diffraction of thermal neutrons has become a powerful tool for solving various actual problems of materials science. To carry out scientific investigations on this theme, a neutron time-of-flight Fourier diffractometer FSD was developed and has been successfully operated for many years at the IBR-2 pulsed reactor in the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna. To ensure high resolution of the instrument, a special correlation technique is used, i.e., a fast Fourier chopper for modulation of the primary-neutron-beam intensity and the reverse time-of-flight method for data acquisition. The current state of the FSD diffractometer and its capabilities are described and examples of performed experiments are given.

On the possibility of investigations with very cold neutrons at pulsed sources

The possibility of investigations with very cold neutrons (VCNs) using the example of the IBR-2 pulsed reactor at the JINR FLNP is considered. Possible application areas and specific features of reactor characteristics for these investigations are briefly described. The results of detailed calculations of VCN generation in different cold moderators, VCN transport in neutron guides, and suppressing the contribution of delayed neutrons are presented.