MARIA (magnetism reflectometer with high incident angle) is a world class vertical sample reflectometer dedicated to the investigation of thin films in the fields of magnetism, soft matter and ...biology. The elliptical vertically focusing guide allows one to measure small samples with a typical size of 1 × 1 cm very efficiently. The double‐bounce polarizer and the in situ pumped 3He SEOP (spin‐exchange optical pumping) neutron spin filter cell for analysing the polarization of the reflected neutron beam can be moved into the beam in seconds. The polarized flux of MARIA amounts to 5 × 107 n (s cm2)−1 at the sample position with a horizontally collimated beam of 3 mrad, a wavelength of λ = 4.5 Å and a wavelength resolution of Δλ/λ = 10%. In the non‐polarized mode a flux of 1.2 × 108 n (s cm2)−1 is achieved in this configuration. MARIA is also capable of grazing‐incidence small‐angle neutron scattering measurements, using a pinhole collimation with two four‐segment slits and an absorber that prevents the focusing of the elliptical guide in the vertical direction.
MARIA is a world class vertical sample reflectometer dedicated to the investigation of thin films in the fields of magnetism, soft matter and biology. With the elliptical vertically focusing guide and a wavelength resolution of Δλ/λ = 10%, the non‐polarized flux at the sample position amounts to 1.2 × 108 n (s cm2)−1. Besides the polarized and non‐polarized reflectivity mode for specular and off‐specular reflectivity measurements, MARIA can also be used to carry out grazing‐incidence small‐angle neutron scattering investigations.
The European Spallation Source (ESS), presently under construction in Lund, Sweden, is a multidisciplinary international laboratory that, once completed at full specifications, will operate the ...world's most powerful pulsed neutron source. Supported by a 3 M Euro Research and Innovation Action within the European Union Horizon 2020 program, a design study (HighNESS) is now underway to develop a second neutron source located below the spallation target. Compared to the first source, which is located above the spallation target and designed for high cold and thermal brightness, the new source is being optimized to deliver higher intensity and a shift to longer wavelengths in the spectral regions of cold neutrons (CNs) (2 to 20 Å), very cold neutrons (VCNs) (10 to 120 Å), and ultracold neutrons (UCNs) (
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500 Å). The second source consists of a large liquid deuterium moderator to deliver CNs and serve secondary VCN and UCN sources, for which different options are under study. These new sources will boost several areas of condensed matter research and will provide unique opportunities in fundamental physics. The HighNESS project is now entering its last year, and we are working toward the Conceptual Design Report of the ESS upgrade. In this paper, results obtained in the first 2 years, ongoing developments, and future perspectives are described.
The Korea Research Institute of Standards and Science (KRISS) has developed and maintained neutron calibration facilities and neutron measurement systems, providing national standards on neutron dose ...equivalent, neutron fluence, and neutron emission rate for Korea. Neutron calibration facilities at KRISS include neutron irradiation facilities and neutron sources, such as radioactive isotope neutron sources, thermal neutrons, and mono-energetic neutrons. Neutron measurement systems at KRISS include the Bonner sphere spectrometer and a manganese-sulfate bath measurement system. The neutron standard facilities and measurement systems at KRISS have supported the researchers. Here, we introduce the ongoing research and development of neutron measurement systems, such as the mono-energetic neutron field generation system, which is currently under development and will be operational within a few months.
A multi‐slit very small angle neutron scattering (MS‐VSANS) instrument has been finally accepted at the China Spallation Neutron Source (CSNS). It is the first spallation neutron source based VSANS ...instrument. MS‐VSANS has a good signal‐to‐noise ratio and can cover a wide scattering vector magnitude range from 0.00028 to 1.4 Å−1. In its primary flight path, a combined curved multichannel beam bender and sections of rotary exchange drums are installed to minimize the background downstream of the instrument. An exchangeable multi‐slit beam focusing system is integrated into the primary flight path, enabling access to a minimum scattering vector magnitude of 0.00028 Å−1. MS‐VSANS has three modes, namely conventional SANS, polarizing SANS and VSANS modes. In the SANS mode, three motorized high‐efficiency 3He tube detectors inside the detector tank cover scattering angles from 0.12 to 35° simultaneously. In the polarizing SANS mode, a double‐V cavity provides highly polarized neutrons and a high‐efficiency 3He polarization analyser allows full polarization analysis. In the VSANS mode, an innovative high‐resolution gas electron multiplier detector covers scattering angles from 0.016 to 0.447°. The absolute scattering intensities of a selection of standard samples are obtained using the direct‐beam technique; the effectiveness of this method is verified by testing the standard samples and comparing the results with those from a benchmark instrument. The MS‐VSANS instrument is designed to be flexible and versatile and all the design goals have been achieved.
The first spallation neutron source based very small angle neutron scattering instrument has been constructed and accepted at the China Spallation Neutron Source. The instrument finds applications in multidisciplinary fields of soft matter, condensed matter physics, materials science and others.
With the construction of the ESS, the European neutron user community is eagerly awaiting the commissioning of the brightest neutron source worldwide in 2021. Parallel to this, there is however the ...ongoing development of neutron science being undertaken at a dwindling number of neutron facilities worldwide. The Jülich Centre for Neutron Science has started a project to develop and design compact accelerator-driven high brilliance neutron sources as an efficient and cost effective alternative to the current low- and medium-flux reactor and spallation sources with the potential to offer science and industry access to neutrons. The project aims to deliver a high brilliance neutron source (HBS), consisting of a compact neutron production and moderator system which provides thermal and cold neutrons with high brilliance efficiently extracted in an optimized neutron transport system. By shaping the experiment holistically from the source to the detector, neutron experiments could be set-up for specific scientific requirements in a flexible and efficient way for the neutron user.
Neutron polarization analysis (NPA) for small‐angle neutron scattering (SANS) experiments using a pulsed neutron source was successfully achieved by applying a 3He spin filter as a spin analyzer for ...the neutrons scattered from the sample. The cell of the 3He spin filter gives a weak small‐angle scattering intensity (background) and covers a sufficient solid angle for performing SANS experiments. The relaxation time of the 3He polarization is sufficient for continuous use for approximately 2 days, thus reaching the typical duration required for a complete set of SANS experiments. Although accurate evaluation of the incoherent neutron scattering, which is predominantly attributable to the extremely large incoherent scattering cross section of hydrogen atoms in samples, is difficult using calculations based on the sample elemental composition, the developed NPA approach with consideration of the influence of multiple neutron scattering enabled reliable decomposition of the SANS intensity distribution into the coherent and incoherent scattering components. To date, NPA has not been well established as a standard technique for SANS experiments at pulsed neutron sources such as the Japan Proton Accelerator Research Complex (J‐PARC) and the US Spallation Neutron Source. It is anticipated that this work will contribute significantly to the accurate determination of the coherent neutron scattering component for scatterers in various types of organic sample systems in SANS experiments at J‐PARC, particularly for systems involving competition between the coherent and incoherent scattering intensity.
Neutron polarization analysis using a 3He spin filter for mainly soft matter systems is demonstrated for small‐angle neutron scattering with a pulsed neutron source; successful separation of the coherent scattering component from the incoherent scattering component due to hydrogen atoms was achieved.
Laue 3D neutron diffraction tomography (Laue 3DNDT) is a novel tomographic approach that enables non‐destructive resolution of the 3D microstructure of polycrystalline materials, utilizing a ...high‐intensity white beam of neutrons, resulting in high experimental efficiency. This article describes the functionality of the fast‐acquisition Laue camera for neutrons (FALCON), a double‐detector system setup used for Laue 3DNDT experiments at the pulse‐overlap diffractometer (POLDI) at the SINQ neutron source of the Paul Scherrer Institute. The reported commissioning includes standard experimental protocols, strategies for acquiring data and a detailed characterization of the measurement system. Finally, single‐crystal measurements for calibration and a full grain map of a CoNiGa oligocrystalline sample, extracted from a pilot study, are presented. A detailed understanding of the performance of the FALCON instrumentation is vital for the future advancement of the Laue 3DNDT algorithm, including, but not limited to, improved morphology reconstructions and strain mapping.
This article introduces the commissioning of the FALCON double‐detector system used for Laue 3D neutron diffraction tomography experiments at the POLDI instrument of SINQ, Paul Scherrer Institute.
Neutron generators (NG) are being increasingly used in various industrial and research areas such as neutron activation analysis, neutron radiography, and neutron capture therapy. In such ...applications of neutron generators, compactness is one of the most important issues. Since a neutron source is generated by deuterium-deuterium (D-D) or deuterium-tritium (D-T) fusion reaction, a relatively thick shield for both fast neutrons and related photons is usually required. In this study, optimization of shielding designs for D-D and D-T neutron generators were investigated by adopting appropriate moderator and shielding materials. Based on the optimized moderator and shield thicknesses, the final dimensions of neutron generators were derived for various source strengths of D-D and D-T neutron conditions. Considering conventional condition of a container, we concluded that a 1010 n/sec D-D source and a 108 n/sec D-T source could be a portable NG.
Placing a compound refractive lens (CRL) as an objective in a neutron beam generates new possibilities for 2D and 3D nondestructive mapping of the structure, strain and magnetic domains within ...extended objects. A condenser setup is introduced that allows correction for the lateral chromatic aberration. More generally, for full‐field microscopy the loss in performance caused by the chromatic aberration can be more than offset by introducing arrays of CRLs and exploiting the fact that the field of view can be much larger than the physical aperture of the CRL. Comments are made on the manufacture of such devices. The potential use is illustrated by comparisons between state‐of‐the‐art instrumentation and suggested approaches for bright‐field microscopy, small‐angle neutron scattering microscopy, grain mapping and mapping of stresses. Options are discussed for depth‐resolved imaging inspired by confocal light microscopy. Finally, experimental demonstrations are given of some of the basic properties of neutron full‐field imaging for a single CRL.
A theoretical description is provided of full‐field neutron microscopy based on refractive optics. The potential use is illustrated by comparison with the state of the art within bright‐field microscopy, small‐angle neutron scattering microscopy, mapping of grains and stresses, and confocal microscopy.
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