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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.

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.

—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.

The article reviews thermal neutron detector developments in the Department of the IBR-2 Spectrometer Complex of the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research (FLNP JINR). A variety of detector types are considered: neutron monitors, ring detectors, position-sensitive detectors (PSD), and scintillation detectors. The experience of exploitation of these detectors at the research facilities of the FLNP JINR is presented.

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.

Three neutron instruments at the Neutron Physics Laboratory (NPL) in Řež near Prague — small-angle scattering (SANS) MAUD, strain scanner SPN-100 and strain diffractometer TKSN-400 — have been modernized recently with new 2D position-sensitive detectors (PSDs) from JINR, Dubna. Here we report on the progress made in relation to the possibilities of the diffractometers due to the improved performance of the detectors. The first part of the paper is dedicated to a detailed description of the hardware and software of the PSDs, as well as its integration with the in-house experimental control software. Then practical examples of neutron scattering experiments for each of the upgraded facilities are presented.

A new gaseous annular sectional thermal-neutron detector for the new neutron diffractometer at the IBR-2 reactor has been designed and manufactured at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research (JINR). The detector is designed to study small-volume samples at high pressure and consists of 16 sections, each one of which is divided into six independent detector elements. We present the main design features of the detector, detecting electronics, data-acquisition and visualization software, and software system for experiment management. The results of the first neutronographic experiments that were carried out with the use of the detector are also presented.

The modernization of the detector system and control system of the neutron powder diffractometer (NPD) in the GEK-5 channel of the VVR-c reactor (Obninsk Branch, Karpov Institute of Physical Chemistry) is described. The PC-connected hardware and software complex, which ensures data acquisition and storage and control of the experiments, is created. The main modules of the NPD automation system and Sonix+ control software package, designed at the Frank Laboratory of Neutron Physics at JINR, are briefly described. The modernization has made it possible to increase the luminosity of the diffractometer and completely automatize the measurement process.

A prototype of a neutron spectrometer based on a gas proportional counter with recoil-proton registration is created at the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research (FLNP JINR) in Dubna. The spectrometer is developed to measure the kinetic energy of protons scattered elastically at small angles that are produced by (n, p) reaction in an environment containing hydrogen. The elaborated prototype consists of two cylindrical proportional counters used as cathodes. They are placed in a gas environment with a common centrally situated anode wire. Studies on the characteristics of the neutron spectrometer were conducted using 252Cf and 239Pu-Be radioisotope neutron sources. Measurements were made with monoenergetic neutrons produced by the 7Li(p, n)7Be reaction when a thin lithium target was bombarded with a proton beam from an EG-5 electrostatic accelerator, as well as with neutrons from the reaction D(d, n) 3He with a gas deuterium target.

The Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research is one of the leading centers of neutron research in Russia. Within the works on the modernization of detector systems, researchers of the laboratory have designed and fabricated linear and area gas-filled position-sensitive detectors of thermal neutrons and the area monitor detector with a low attenuation of the incoming beam. These devices and their main characteristics have been described.

Development of new high-flux-intensity neutron sources and the need to equip them with efficient spectrometers raises the problem of designing special-purpose direct-beam monitors-detectors. These detectors feature an extremely low efficiency and a very low attenuation of the incident neutron beam. In this work, a two-coordinate position-sensitive monitor-detector is described that was developed for real-time recording of the profile of neutron beams generated by both steady and pulsed neutron sources. The basic parameters of this device are the following: a coordinate resolution of 4 × 4 mm2, a sensitive area of 100 × 100 mm2, and a recording efficiency of 10−6−10−2. Use of nitrogen as a converter makes it possible to achieve a record low efficiency and still maintain other parameters at a desired level. The device can be combined not only with high-flux-intensity neutron sources already in use worldwide but also with next-generation sources being developed in the United States (SNS) and Japan (JPARC).

A one-dimensional position-sensitive detector of thermal neutrons has been developed to equip high-efficiency neutron spectrometers at the ИБР-2 research reactor. The detector is based on a multiwire proportional chamber filled with a mixture of 3He + CF4 and has an active area of 200 × 80 mm and a spatial resolution of 2 mm. The detector has been used to good effect in the REFLEX and HRFD spectrometers of the ИБР-2 reactor, as well as in the diffraction facility of the ИВВ-2M research reactor (Zarechnyi, Russia).

A user interface that provides the means for scheduling an experiment and controlling its performance is described. The current state of a spectrometer, the programs, and the experimental results can now be presented on the Internet as dynamically formed protocols and graphs. After giving a password, an experiment may be controlled via the Internet. The client can use the Internet without the need for any applied programs. The software package is designed for experiments in the field of condensed matter and nuclear physics and is ready for immediate use.

The possibility of the joint operation of a ФЭУ-165 photomultiplier based on microchannel plates and a BGO crystal, which are cooled to a temperature required for the operation of a semiconductor Ge detector, is investigated taking into account the temperature dependence of proper PMT characteristics. The system was cooled from room temperature to –140°C for 8 h. The limiting temperature at which the PMT holds its serviceability was determined, and the temperature changes in the spectroscopic characteristics of the system (the energy resolution and signal-to-noise ratio) were studied.

A position-sensitive detector for the YuMO time-of-flight small-angle neutron scattering spectrometer at the IBR-2 pulsed reactor (Dubna, Russia) is proposed. Position sensitivity is realized by determining the polar and radial components of the scattering vector. The detector consists of eight independent 3He annular counters with high-resistance wires lying in one plane and occupying the same gas volume. To determine the coordinates, the charge division method is used. The signals from both ends of the wire are picked up by charge-sensitive preamplifiers and digitized by an analog-to-digital converter (ADC) with a fixed dead time. The VME-standard TMS320C40-based processor block of the data acquisition system is responsible for determining the coordinates and accumulating spectra. The preliminary results of the tests of the detector are presented.

For the investigation of neutron induced fission of heavy nuclei in the resonance energy range the fast multilayer ionization fission chamber with a 239Pu content of 1.6 g was constructed. The chamber is compact and a minimum of material has been used for its construction. The chamber is divided into 19 sections containing no more than 100 mg of 239Pu in a section whose intrinsic capacity is less than 100 pF. By using fast preamplifiers and constant fraction discriminators together with the combined method of amplitude and pulse length discrimination the background due to α-particles is suppressed and a less perturbed pulse height distribution is obtained. The absolute fission fragments detection efficiency of the chamber is (60±8)%. Its time resolution does not exceed 2.6 ns.

A preamplifier with a rise and fall time of ∼2.5 ns is described. At the output of a transmitting 50-Ω cable with matched terminations at both ends, and the input-equivalent circuit noise is 20 μV at an amplification factor of 7.5. Eight such preamplifiers are placed inside a unit with dimensions of 8 × 16 × 4 cm.

Gamma-ray spectra from239Pu(n,f) reaction were measured with the gamma spectrometer on the pulsed reactor IBR-30. The fast 19-section ionization chamber with 1.6 g of239Pu targets was used. The fission gamma-rays within the 32 ns time window were measured using a Ge(Li) detector. Based on the measured gamma-ray spectrum in the (0.1–1.8) MeV interval, the total number of emittedγ-quanta-multiplicity 〈N γ tot 〉 and total energy of γ-quanta per fission event, 〈E γ tot 〉, were calculated. The results were 7.0±0.6γ/fission and 6.8±0.5 MeV/fission respectively.