Theoretical Optimization of Neutron and Physical Characteristics of a Multiplying Pulsed Neutron Source Based on a Proton Accelerator

Physics of Particles and Nuclei Letters - The neutron source operating at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research (JINR, Dubna, Russia), based on an IBR-2M...     

Neutron activation analysis in the life sciences

Development of methods for instrumental neutron activation analysis (INAA) and their applications in the life sciences are reviewed. Emphasis is placed on epithermal activation with reactor neutrons (ENAA), and the advantages of this technique in analysis of environmental objects are shown. The results of applied INAA studies in the field of the life sciences carried out at the world’s leading nuclear centers are reported. Experience in employing a radioanalytical complex at the IBR-2 reactor (Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna) for such studies is summarized.     

Analysis of Internal Stress in a Tape Subsrate Made of the AISI 310S Stainless Steel for the Second-Generation HTS Wires Using Neutron Stress Diffractometry

Technical Physics - Neutron stress diffractometry is used to study internal (residual) stress in a tape made of the AISI 310S stainless steel with a thickness of 100 μm and a width of 4 mm in...     

Neutron Fourier diffractometer FSD for residual stress studies in materials and industrial components

Neutron diffraction study of residual stresses in materials became widely used in the world due to high penetrating power of neutrons. Therefore, to study residual stresses, the FSD (Fourier stress diffractometer) was developed at the IBR-2 reactor channel (Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia), which, due to a special correlation technique (a fast Fourier chopper for modulating the primary neutron beam intensity and the RTOF method for data acquisition) makes it possible to obtain high-esolution diffraction spectra Δd/d = 4 × 10^-3. This diffractometer was developed taking into account world experience in the study of residual stresses in materials; experience in the development of such devices in Russia and abroad was also used. The FSD diffractometer itself and its current state are described.     

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.     

Development of gas-filled position-sensitive detectors of thermal neutrons at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research

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.     

Neutron diffraction investigations of residual stresses around a zirconium-stainless steel interface in a bimetallic adapter

This paper presents the results of neutron diffraction investigations of the residual stress state around a zirconium-stainless steel interface in a bimetallic adapter used for some channels in RBMK-type reactors. The adapter consists of a cylinder with a complex cross section with an outer stainless steel layer and an inner zirconium layer. The experiments are carried out on a Pulse overlap time-of-flight diffractometer (POLDI, SINQ) (Paul Scherrer Institut, Switzerland), a Fourier stress diffractometer (FSD), and high resolution Fourier diffractometer (HRFD) at the IBR-2 pulsed reactor (Frank Laboratory of Neutron Physics, JINR, Dubna, Russia).     

Neutron diffractometer for real-time studies of transient processes at the IBR-2 pulsed reactor

A specialized diffractometer intended for use in studying real-time transient processes in condensed media, which also allows the recording of Bragg diffraction and small-angle neutron scattering spectra, has been created at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research. Frequently, only the given formulation of the experiment with the continuous recording of information on the process enables us to obtain data required for the correct interpretation of events. One of the crucial parameters of such experiments is the minimal time interval in which sufficient statistics can be acquired. The diffractometer parameters make it possible to measure diffraction and small-angle spectra within minute and even second (for certain types of transition processes) ranges. The possibilities of neutron scattering are discussed as applied to the study of transient processes, the diffractometer design is described, and its main characteristics and the test experiment results are presented.     

Automation of the quantitative determination of elemental content in samples using neutron activation analysis on the IBR-2 reactor at the frank laboratory for neutron physics, joint institute for nuclear research

Software for the automated quantitative determination of element concentrations in samples is described. This software is used in neutron activation analysis (NAA) at the IBR-2 reactor of the Frank Laboratory for Neutron Physics, Joint Institute for Nuclear Research (FLNP JINR).     

Determining the Fast Neutron Flux Density and Transmutation Level Measurements in ADS by the Use of a Threshold Nuclear Reaction

Determining the Fast Neutron Flux Density and Transmutation Level Measurements in the ADS by the use of a Threshold Nuclear Reaction. The aim of the project was determining the fast neutron flux density by using data from the Quinta experiment (E+T RAW collaboration). The experimental assembly based on natural uranium was irradiated by a 660 MeV proton beam. To gain the knowledge about the neutron flux inside the experimental assembly, nuclear threshold reactions of (n, xn) type were used. The level of isotopes production are measured by the activation method using a gamma radiation HPGe detector. This paper describes the Quinta assembly, experimental results, calibration procedure and average high energy neutron calculation based on yttrium (Y-89) isotopes production. In the future, results and conclusions from an experiment like this could be useful to design accelerator-driven subcritical systems (ADS) or other 4th generation fast reactors. The investigation has been performed at the Laboratory of High Energy Physics, JINR.     

Automation system for measurement of gamma-ray spectra of induced activity for multi-element high volume neutron activation analysis at the reactor IBR-2 of Frank Laboratory of Neutron Physics at the joint institute for nuclear research

The automation system for measurement of induced activity of gamma-ray spectra for multi-element high volume neutron activation analysis (NAA) was designed, developed and implemented at the reactor IBR-2 at the Frank Laboratory of Neutron Physics. The system consists of three devices of automatic sample changers for three Canberra HPGe detector-based gamma spectrometry systems. Each sample changer consists of two-axis of linear positioning module M202A by DriveSet company and disk with 45 slots for containers with samples. Control of automatic sample changer is performed by the Xemo S360U controller by Systec company. Positioning accuracy can reach 0.1 mm. Special software performs automatic changing of samples and measurement of gamma spectra at constant interaction with the NAA database.     

基于大功率LED的中子墙光刻度系统

光刻度系统是中子墙探测器系统的重要组成部分, 用于中子墙前端电子学的刻度和探测器工作性能变化的监测. 通过对基于发光二极管(LED)作为光源的中子墙光刻度系统方案开展了细致的测试研究, 确定了基于快脉冲驱动的大功率蓝光LED(3W)的中子墙光刻度系统方案, 对中子墙探测单元进行了初步刻度测试, 刻度结果能很好地满足光刻度要求, 表明对于快塑料闪烁体探测器该方案是一种较为理想的方案.     

Development and prospects of Very Small Angle Neutron Scattering(VSANS) techniques

Very Small Angle Neutron Scattering(VSANS) is an upgrade of the traditional Small Angle Neutron Scattering(SANS) technique which can cover three orders of magnitude of length scale from one nanometer to one micrometer. It is a powerful tool for structure calibration in polymer science, biology, material science and condensed matter physics. Since the first VSANS instrument, D11 in Grenoble, was built in 1972, new collimation techniques,focusing optics(multi-beam converging apertures, material or magnetic lenses, and focusing mirrors) and higher resolution detectors combined with the long flight paths and long incident neutron wavelengths have been developed.In this paper, a detailed review is given of the development, principles and application conditions of various VSANS techniques. Then, beam current gain factors are calculated to evaluate those techniques. A VSANS design for the China Spallation Neutron Source(CSNS) is thereby presented.     

Epithermal Neutron Activation Analysis at the IBR-2 reactor of the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research (Dubna)

Experience of the Neutron Activation Analysis (NAA) Department in employing epithermal activation in life sciences and materials science is summarized. The potential of a combination of epithermal activation and the suppression of Compton scattering and contributions from cascade-photon-emitting elements for raising NAA-based analytical studies up to a new level are discussed.     

Neutron spectrometer based on a proton telescope with electronic collimation of recoil protons

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.     

Adventures in Neutron Interferometry

A brief history of Neutron Interferometry is presented, from a personal perspective. Comments and a message from Professor Sam Werner are included.     

Neutron stars in relativistic hadron-quark models

Neutron star properties are computed in relativistic models that contain both hadron and quark degrees of freedom. Neutron matter is assumed to have a low-density phase described by quantum hadrodynamics (QHD) and a high-density phase described by quantum chromodynamics (QCD). Several different QHD models and approximations are employed; all use parameters that reproduce the binding energy and density of equilibrium nuclear matter. Calculated neutron star properties depend primarily on the high-density equation of state and cannot be inferred from the symmetry energy or compressibility of equilibrium nuclear matter. If interactions are neglected in the QCD phase, the density of the hadron-quark phase transition is determined by one free parameters, which is the energy/volume needed to create a “bubble” that confines the quarks and gluons. Observed neutron star masses do not constrain this parameter, but stable neutron stars with quark cores can exist only for a limited range of parameter values. When second-order gluon-exchange corrections are included in the QCD phase, these conclusions are unchanged, and the parameter values that lead to stable hadronquark stars are restricted even further.     

Meeting Reports

7th Laboratory Course Held at Forschungszentrum Jülich, by Reiner Zorn Orbital Physics and Novel Phenomena in Transition Metal Oxides Workshop Meets in Berlin, by D. N. Argyriou Serpong Hosts Expert Meeting of Neutron Scattering Experiments, by A. Ikram LANSCE Hosts First Winter School on Neutron Scattering, by James J. Rhyne     

散裂中子源高气压二维位置灵敏3He探测器的实验研究

为满足中国散裂中子源多功能反射谱仪中子探测器的基本物理要求:有效面积达到200 mm×200 mm、探测效率大于50%（2Å）、位置分辨好于2 mm等,中国科学院高能物理研究所研制了3He高气压二维多丝正比室位置灵敏中子探测器。该探测器采用二维多丝室结构,腔体内充3He/C₃H₈（6 atm/2.5 atm）的组合气体。本文首先利用Am/Be中子源完成对探测器全面积均匀性测试,均匀性指标达到了95.1%;探测器在中国散裂中子源的20号束流线站安装后,对其进行了在束测量,通过飞行时间选取波长2.8Å的慢中子,测量了探测器二维位置分辨和二维成像性能。在X方向（垂直于阳极丝的方向）的位置分辨为0.99 mm,Y方向（平行于阳极丝的方向）的位置分辨为1.36 mm,探测器具有很好的二维位置分辨和二维成像能力。测量结果表明探测器满足反射谱仪的研制要求。     

浦项中子装置上209Bi中子全截面测量(英文)

在浦项中子装置(PNF) 的100 MeV电子直线加速器上利用透射法和飞行时间法测量了209Bi 的0.1~100 eV的中子全截面。文中对于实验装置特点、用吸收片法拟合本底、拟合中子飞行距离和时间零点的处理过程做了较为详细的描述。测量结果与以前发表的实验数据以及评价数据ENDF/B-VII.1 做了比较,比较结果符合得较好。