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The sharp variation of neutron attenuation at certain energies specific to particular nuclides (the lower range being from ~1eV up to ~1keV), can be exploited for the remote mapping of element and/or isotope distributions, as well as temperature probing, within relatively thick samples. Intense pulsed neutron beam-lines at spallation sources combined with a high spatial, high-timing resolution neutron counting detector, provide a unique opportunity to measure neutron transmission spectra through the time-of-flight technique. We present the results of experiments where spatially resolved neutron resonances were measured, at energies up to 50keV. These experiments were performed with the intense flux low background NOBORU neutron beamline at the J-PARC neutron source and the high timing resolution (~20ns at epithermal neutron energies) and spatial resolution (~55µm) neutron counting detector using microchannel plates coupled to a Timepix electronic readout. Simultaneous element-specific imaging was carried out for several materials, at a spatial resolution of ~150µm. The high timing resolution of our detector combined with the low background beamline, also enabled characterization of the neutron pulse itself – specifically its pulse width, which varies with neutron energy. The results of our measurements are in good agreement with the predicted results for the double pulse structure of the J-PARC facility, which provides two 100ns-wide proton pulses separated by 600ns, broadened by the neutron energy moderation process. Thermal neutron radiography can be conducted simultaneously with resonance transmission spectroscopy, and can reveal the internal structure of the samples. The transmission spectra measured in our experiments demonstrate the feasibility of mapping elemental distributions using this non-destructive technique, for those elements (and in certain cases, specific isotopes), which have resonance energies below a few keV, and with lower resolution for elements with relatively high resonance energies in the 1–30keV range. [ABSTRACT FROM AUTHOR]

Abstract: We measured two-dimensional transmission spectra of pulsed neutron beams for a Japanese sword sample. Atom density, crystalline size, and preferred orientation of crystals were obtained using the RITS code. The position dependence of the atomic density is consistent with the shape of the sample. The crystalline size is very small and shows position dependence, which is understood by the unique structure of Japanese swords. The preferred orientation has strong position dependence. Our study shows the usefulness of the pulsed neutron transmission method for cultural metal artifacts. [Copyright &y& Elsevier]

Abstract: The RITS code was developed for quantitative evaluation and visualization of crystalline structural information (e.g. crystallographic texture, preferred crystal orientation, crystallite block size and crystal lattice strain, etc.) of a material, analyzing position-dependent Bragg edge transmission spectra measured in an imaging experiment with pulsed neutrons. Originally, this code was neither able to deal with all the crystal structures that were classified into 230 types of space groups, nor applicable to materials composed of multi elements and multi crystalline phases. Therefore, we improved the RITS code for expansion of its capability, and then performed some demonstrations of simulation calculations and profile fitting analyses of experimental data. In this article, we present the new algorithm and the new functions of the improved RITS code, and the results of the simulation calculations and the experimental data analyses. [Copyright &y& Elsevier]

Abstract: A new facility for combined neutron imaging and neutron diffraction called IMAT is currently being built at the pulsed neutron spallation source ISIS in the United Kingdom. Analytical techniques will include neutron radiography, neutron tomography, energy-selective neutron imaging, residual strain analysis and spatially resolved texture analysis. The instrument will be available for a wide range of materials science applications with a main emphasis on engineering studies. It is expected that IMAT will start operation in 2015. [Copyright &y& Elsevier]

Abstract: Pulsed neutron imaging methods provide information on crystallographic structure, magnetic field, elemental composition, hydrogen bound state and other material features. Such methods have been expected to be a powerful complement to the traditional imaging method. Data analysis codes, detectors and new applications are being developed in Japan, and a new imaging beam line is being constructed at J-PARC. Here, recent progress in Japanese research on pulsed neutron imaging is presented, and a design for construction of the new imaging beam line is reported. [Copyright &y& Elsevier]

Abstract: A small neutron facility based on a compact accelerator has some advantages over a large facility in terms of accessibility and usability. One of main objects of a compact accelerator neutron source is neutron imaging. Therefore, we performed an optimization study on a pulsed thermal neutron source and an epithermal one based on a compact accelerator in order to use it for thermal neutron imaging and resonance neutron imaging. We have carried out simulation calculations to evaluate the neutron intensity change depending on the moderator size taking into account spatial resolution. The intensities from a small moderator were higher than that from a larger one when compared at the same L/D. However, field of view (FOV) constrained the minimal moderator size. At L/D of 100 and FOV from 10 to 30cm, the optimal moderator size giving the highest intensity was from 10 to 12cm. [Copyright &y& Elsevier]

Abstract: Localized neutron beam monitors are very useful for applications related to the measurement of the so called single event effects (SEE) in electronic devices, especially at spallation neutron sources. Although the high-energy component of the spectrum typically represents a concern for SEE, nevertheless the measurement of the flux over the whole energy range is also desirable. Indeed, the possibility of measuring the spectral neutron fluence rate is instrumental for a reliable and complete assessment of the robustness of the irradiated devices to SEE induced by neutron fields that close resemble the atmospheric one, that extends up to 109 eV energy. In this paper, an approach to monitor the epithermal energy region of the pulsed neutrons beams available at the ISIS spallation neutron source is presented. It is based on the exploitation of the resonances of the 235U(n,f) reaction and the detection of the fission fragments by means of single crystal diamonds. These explorative tests are intended as complementary to the use of diamond detectors for localized fast neutron beams monitoring and the results obtained, while assessing this aspect, also show the possibility to measure the relative spectral neutron fluence rate at different energies in the electronvolt region. [Copyright &y& Elsevier]

Abstract: Paper presents results of measurements of neutron spectra with Bonner spheres spectrometer around radiotherapeutic linac producing undesirable photoneutrons and around plasma focus device PF-1000 in which neutrons are generated in 2H + 2H → n + 3He reaction. In the Bonner spheres an active detector, proportional counter filled with 3He, was replaced by passive one to avoid overloading of the active detector during very short period of neutrons generation. For the measurements around linac track detectors with 10B radiator were used and around plasma focus device pairs of TLDs (6LiF and 7LiF). [ABSTRACT FROM AUTHOR]

A compact cubic-anvil high-pressure device was developed for in situ neutron powder diffraction studies. In this device, a cubic shaped pressure medium is compressed by six anvils, and neutron beams pass through gaps between the anvils. The first high-pressure experiment using this device was conducted at J-PARC and clearly showed the neutron diffraction patterns of Pb. Combining the cubic-anvil high-pressure device with a pulsed neutron source will prove to be a useful tool for neutron diffraction experiments. [ABSTRACT FROM AUTHOR]

Two experiments were performed to adapt spin echo scattering angle measurement (SESAME) to pulsed neutron sources. SESAME is an interferometric method that provides enhanced resolution of neutron scattering angles without the loss of neutron intensity that results when collimation is used to improve angular resolution. The method uses the neutron equivalent of optical wave plates to produce a phase difference between the two neutron spin components of a polarized neutron beam. Because the wave plate is inclined to the neutron beam, this phase difference depends sensitively on the trajectory of the neutron. In the absence of a sample, a second wave plate, which is parallel to the first, undoes the phase difference introduced by the first wave plate, producing a polarization identical to that of the incident neutron beam. When a scattering sample is placed between the two neutron wave plates, the cancellation of the phase difference between the neutron spin states is not perfect and the resulting neutron-beam polarization is a measure of the distribution of scattering angles. In the first experiment, thin (30 and 60 µm-thick) magnetized Permalloy films were used as neutron wave plates. In a second experiment, current-carrying solenoids with triangular cross sections were used as birefringent prisms for neutrons. The arrangement of these prisms was such that they mimicked the effect of the neutron wave plates in the first experiment. In both experiments, correlation lengths in the scattering sample of about 1000 Å were probed using very simple and inexpensive equipment. These experiments brought to light a number of advantages and disadvantages of implementing SESAME at pulsed neutron sources and provided insights into the relative merits of SESAME and traditional small-angle neutron scattering. [ABSTRACT FROM AUTHOR]

Abstract: Currently, neutron resonance spin echo (NRSE) spectrometers are being applied to pulsed neutron sources at J-PARC. High-performance NRSE requires the development of a resonance neutron spin flipper (RSF) with high frequency. We have fabricated an RSF of pure aluminum having a frequency greater than 500kHz and a wavelength from 0.30 to 0.75nm. [Copyright &y& Elsevier]

Steady sextupole magnet has a function as neutron beam focusing device with chromatic aberration. In order to solve the chromatic aberration we have developed a pulsed sextupole electromagnet for focusing pulsed neutrons. In the magnet, the gradient of magnetic field is controlled in time to the neutron passage through the magnet, as faster neutrons feel a stronger magnetic field gradient than slower neutrons. The idea, design, current status and application of the magnet are described. [Copyright &y& Elsevier]

Abstract: Single crystal diamond (SDD) detectors coupled to fast digital data acquisition were tested as monitors of fast neutrons at the ISIS pulsed spallation neutron source. The ISIS pulsed neutron beams are generated by proton induced spallation on a tungsten tantalum target at 50Hz repetition rate. The SDD signal was digitized at 1GHz to reconstruct the deposited energy and time of flight (t ToF) of each detection event. The SDD system was used reliably and almost continuously over a period of several days. The results of the biparametric measurements are in qualitative agreement with predictions based on the proton beam pulse structure and the energy deposited in the SDD by the main neutron interaction processes. [Copyright &y& Elsevier]

In this paper, we present preliminary results on the feasibility of employing a low energy (2 kJ, 31 kV) plasma focus device as a portable source of pulsed neutron beams (2.45 MeV) generated by nuclear fusion reactions D-D, for the 'in situ' analysis of substances by nuclear activation. This source has the relevant advantage of being pulsed at requirement, transportable, not permanently radioactive, without radioactive waste, cheap, among others. We prove the feasibility of using this source showing several spectra of the characteristic emission line for manganese, gold, lead, and silver. [ABSTRACT FROM AUTHOR]

Abstract: We have developed a prototype rotating-permanent magnet sextupole lens (named rot-PMSx) for more efficient experiments with neutron beams in time of flight (ToF) mode. This lens can modulate the focusing strength over range . Synchronization between the modulation and the beam pulse produces a focused beam without significant chromatic aberration. We anticipate that this lens could be utilized in focusing small angle neutron scattering (SANS) instruments for novel approach to high resolution SANS. We carried out experiments testing the principle of this lens at the very cold neutron (VCN) beamline (PF2) at Institut Laue-Langevin (ILL), France. The focused beam image size at the detector was kept constant at the same beam size as the source over a wavelength range of in focal length of . The flux gain was about 12 relative to a beam without focusing, and the depth of focus was quite large. These results show the good performance of this lens and the system. Thereupon we have demonstrated the performance of this test bed for high resolution focusing of VCN-SANS for a well-studied softmatter sample; a deuterium oxide solution of Pluronic F127, an (PEO)100(PPO)65(PEO)100 tri-block copolymer in deuterium oxide. The results of the focusing experiment and the focusing VCN-SANS are presented. [Copyright &y& Elsevier]

Abstract: We report a successful demonstration of a high S/N ratio spin flip chopper (SFC) system for pulsed neutron sources. The system consists of two SFCs and each SFC consists of a radio frequency (RF) flipper and Soller magnetic supermirrors. The aperture of the Soller mirror was 18mm in width and 20mm in height. The S/N ratio of the system was 306:1. This system is going to be installed to measure neutron lifetime precisely using the cold-neutron beam line, BL05 polarized-beam branch, at the Materials and Life Science Experimental Facility (MLF) in Japan Proton Accelerator Research Complex (J-PARC). [Copyright &y& Elsevier]