[en] Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources. (report on progress)

[en] The neutron source for producing neutron beams, fission reactors which use reaction between neutron and uranium 235, particle accelerators for particles such as protons, deuterons, tritons, lithium or beryllium ions, such radioisotopes as emitting α- or γ-rays which react with beryllium atoms, and spontaneously-fissionable nucleus like Cf 252, is first explained, followed by explanation of neutron moderation for kinetic energy, filtration of γ-rays, neutron beam transport system, beam shutters, and irradiation room designs. Intensity and beam quality of neutron beam are discussed, together with cold neutron, ultra-cold neutron, epithermal and fast-neutron beams. Measurements of fluence rate and L/D based on ASTM Standard E803 Method (Standard Test Method for determining the effective collimation ratio of neutron radiography beams) and others are briefly explained. (S. Ohno)

[en] An improved method and apparatus is described for measuring the thermal neutron diffusion coefficient of materials surrounding a well borehole. Improved coefficient data yield improved porosity and water saturation determinations. (E.C.B.)

[en] In neutron measurements involving a point neutron source and a detector, if the detector output is the same when the source and the detector are interchanged, the measurement is reciprocal. The measurement is nonreciprocal if the detector output is not the same upon interchange. In neutron logging when a fast neutron source and a slow neutron detector are used, and there is an interface between the source and detector, the measurement is nonreciprocal. Experimental data are presented showing this effect in using a neutron-thermal neutron tool inside a 10-cm diameter borehole through a 70-cm thick water zone bounded above and below by air. This nonreciprocal effect can be used to create an interface log by using similar detectors equally spaced above and below a neutron source, depth shifting one or both, and subtracting the two individual logs. Another result is that, in general in neutron logging, the apparent depth of an interface is dependent on whether the detector is above or below the source. (author)

[en] Authors discuss prospects for the development of the Kurchatov Neutron Center with the cold hydrogen source, neutron guides and new experimental facilities in the neutron guide and reactor halls on the basis of IR-8 reactor

[en] The device of the present invention comprises a neutron supply device equipped with a neutron radiation source using radioactive isotope elements, a neutron moderator, a neutron coolants, a neutron wavelength selection device and a neutron conduit, and a scattering vessel equipped with a dimensional neutron detector for detecting neutrons scattered by irradiating neutrons having a wavelength selected by the neutron wavelength selection device to specimens. The neutron conduit is bent so that the neutron supply device and the scattering vessel are not arranged linearly. With such a constitution, the leakage of neutrons from the neutron supply device into the scattering vessel by neutron streaming can be minimized. With such a constitution, a neutron receiving port for receiving the supply of thermal neutrons from the outside can be disposed without disposing a neutron radiation source in the device main body, and the device can be connected to a small-sized research reactor or used in a circumstance of receiving supply of thermal neutrons previously. (I.S.)

[en] Various uses of neutrons are being watched in many fields such as industry, medical technology and radiation protection. Especially, high energy neutrons above 15 MeV are important in a radiation exposure issue of an aircraft and a soft error issue of a semiconductor. Therefore neutron fluence standards for the high energy region are very important. However, the standards are not almost provided all over the world. Three reasons are mainly considered: (1) poor measurement techniques for the high energy neutrons, (2) a small number of high energy neutron facilities and (3) lack of nuclear data for high energy particle reactions. In this paper, the present status of the measurement techniques, the facilities and the nuclear data is investigated and discussed. In NMIJ/AIST, the 19.0-MeV neutron fluence standard will be established by 2010, and development of high energy neutron standards above 20 MeV is also examined. An outline of the development of the high energy neutron standards is also shown in this paper. (author)

[en] The High Flux Neutron Radiography Facility (HFNRF) has been fabricated, tested and used successfully. This paper describes the final design features and presents the results of the radiation measurements made during the characterization tests. A complete neutron spectrum (from 10^-8 to 15 MeV) has been measured with the aid of activation foils. Gold foils were used to determine a thermal neutron flux of 9.4 x 10⁷ n·cm^-2s^-1 at the image plane in the Sandia Annular Core Research Reactor (ACRR) operating at 1.0 MW. The reactor can be operated at 20 MW for 10-second periods with the radiography tube in the central cavity. In pulse mode with peak power of 24,000 MW and a 7.6 ms FWHM ∼1.9 x 10¹⁰ n·cm^-2 will be generated with a peak flux of 2.3 x 10¹² n·cm^-2s^-1

[en] Until recently, spectral characterization of fluence for high-power nuclear reactors has generally been inferred from neutron flux-spectrum measurements and a knowledge of the power time-history. Such measurements are usually made through the use of the multiple-foil technique. The problem with measuring fluence by this method has been that some foils routinely used to define the neutron energy spectrum have products with relatively short half-lives, and therefore provide the flux level only near the ends of the irradiation. Obtaining accurate fluences from these flux values for long power reactor irradiations is often not possible, however, because total reactor power may not reflect local power at an experimental location, due to movement of control rods, and changes in reactor loading. An extension of the multiple-foil technique is now being implemented where monitors with stable (⁴He and ¹⁴⁸Nd) and relatively long-lived (⁶⁰Co, ¹³⁷Cs) products are included. Helium accumulation fluence monitors (HAFM's) which consist of miniature vanadium capsules containing various materials with different (n,α) cross section energy responses have been added to the foil sets. The generated helium is measured with approximately 2% absolute accuracy by isotope dilution mass spectrometry. This expanded multiple-foil technique gives a direct measure of fluence-spectrum, instead of the more usual flux-spectrum. Such information is most important for accurate correlation of irradiation effects data

[en] In 1932, when Chadwick obtained the first unambiguous evidence for the existence of the neutron, his discovery confirmed the widely held belief that there existed a particle with zero charge and a mass similar to that of the proton. Indeed, as early as 1920, Lord Rutherford had suggested such a possibility in a lecture to the Royal Society. The discovery of the neutron had an immediate and dramatic impact in several areas. The nucleus, which had hitherto been regarded, somewhat unsatisfactorily, as a combination of protons and electrons, was now seen as comprising of protons and neutrons. This in turn lead to a proper understanding of the nature of isotopes and provided a fresh basis for nuclear theories. This paper examines the nature and properties of the neutron, and describes some facets of its remarkable role in contemporary science and technology. The aspects covered are its properties, the production and detection of neutrons, the reactions between neutrons and nuclei, fission reactions, neutron scattering, pulsed neutron scattering and neutron spectroscopy. (author)