実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）承認日 Date of Approval 2014/8/18
Takashi Ohhara
承認者 Approver
2014/8/13
提出日 Date of Report

Experimental Report
課題番号 Project No.

装置責任者 Name of Instrument scientist

2014A0070

Takashi Ohhara

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）Time-of-flight3D

neutrondiffractionformultigrain

SENJU (BL18)

crystallography
実験責任者名 Name of principal investigator

実施日 Date of Experiment

May 21 - June 3, 2014

Soeren Schmidt
所属 Affiliation

Technical University of Denmark
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.

These are the samples investigated during the experiment:
1. Iron rods (100% Fe) with a diameter of 5 and 10 mm;
2. Nickel-Titanium (Nitinol) rods, 10 mm diameter;
3. A Bismuth (Bi) rod, 10 mm diameter;
4. Ni-superalloy rods, diameter around 2 mm;
5. Tungsten (W) pseudocubes, side of about 5 mm.

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

Experimental method. 3D neutron Diffraction (3DND) is a novel technique that uses neutrons to study thestructure of polycrystalline materials, such as metals and rocks, in three dimensions. The technique is basedon 3D X-ray Diffraction [1] and returns a 3D map showing position and orientation of the grains composing
the considered sample.
The 3DND experiment performed at the SENJU beamline was the first of its kind, combining the use of atime-of-flight beam with the simultaneous acquisition of transmission and diffraction information via a
combination of near- and far-field detectors.
Information in direct and orientation space were simultaneously recorded using, respectively, an event
counting detector, later called near-field detector, and the diffraction detector banks of the beamline, latercalled far-field detector [2,3]. The sample was placed on a rotation stage at the centre of the diffraction
detector banks, with the near-field detector a few centimetres downstream. See Fig.1 for a sketch of thedetectors arrangement.

Figure 1. a: Overview of the detector setup used at BL18, J-PARC. It combined 36 scintillator detectors (far-fielddetectors, named S1…S5 and N1…N7) and an MPC one (near-field detector, noted as NF in the figure). The
near-field detector has an active area of 28x28mm2 and pixel size of 55µm. The far-field detectors consist of 12
modules made of three detectors each, arranged as shown in b. Each module composing the far-field detector has asize of 256x256mm2, with a pixel size of 4mm. Modified figure from [2].

Most of the beamtime was spent imaging Iron, Bismuth or Nickel samples at a number of different
projections, evenly spaced across 180 or 360 degrees. A number of test measurements have also been
performed to study the Tungsten and Nitinol rods: these materials require longer exposure times and havebeen imaged for several hours without rotating.
Data analysis. The data collected by the near- and far-field detectors are being analysed using a
combination of ad-hoc developed and existing alhgorithms [4,5]. The basic idea is to derive the orientationof the grains from the diffraction pattern collected by the far-field detector, and the shape of the grains fromthe transmission signal collected by the near-field detector. In particular, the shape of the grains isdetermined using the corresponding “extinction spots”, recorded by the near-field detector when a grainwith low-index reflections and high structure factor values satisfies the Bragg condition (see Fig. 2) [6].

For each grain, the association between a certain shape and orientation is done using the properties of thetime-of-flight beam, where neutrons with different energies illuminate the sample at different times.
To test the data analysis procedure, McStas Monte Carlo simulations are also beign used [7].

Figure 2. Different steps of the analysis procedure for the transmission data collected by the near-field detector: (a) raw
data, (b) data cleaned for the open beam, (c) a threshold cut is applied to the cleaned dataset and the result is thenbinarised. The arrow points to an extinction spot. Sample considered: Armco Iron rod with 1cm diameter.

Results. During the experiment at BL18, we imaged 10 samples and collected tomographic data for 4 ofthem. Typical transmission and diffraction data are shown in Fig. 3. For the grain map, we estimate aresolution similar to what typically achieved with 3D X-ray diffraction [1].

Figure 3. Typical transmission and diffraction signal recorded while imaging an Iron cylinder at the beamline BL18,J-PARC. The transmission signal (above), collected by the near-field detector, is shown before being processed. In thefirst frame (left) the dark spots, pointed by arrows, are the extinction spots, recorded when a grain satisfies the Bragg
condition. Regions marked by (a) and (b) consist of small grains showing powder-like behavior and are also visible inthe second frame, collected about 0.015Å later. The diffraction signal collected by the far-field detectors (below) isvisualized using STARGazerP [3]. The size of the diffraction spots on the far-field detector is proportional to thevolume of the corresponding grain. The rings (c) are due to small, possibly deformed grain showing a powder-likebehavior, located in regions like (a) and (b).

References[1] Poulsen, H.F. et al., (2001). Journal of Applied Crystallography, 34, 751-756. [2] Tamura, I. et al.,(2012). J. Phys.: Conf. Ser. 340, 012040. [3] Tremsin, A.S. et al., (2012). Strain, 48, 296-305. [4] Ohhara, Tet al., (2009). Nuclear Instruments and Methods in Physics Research Section A, 600, 195-197. [5] Schmidt,S. (2014). J. Appl. Cryst (2014), 47, 276-284. [6] Ludwig, W. et al., (2008). Journal of Applied
Crystallography, 41, 302-309. [7] Lefmann, K. and Nielsen, K. (1999). Neutron News 10, 20-23.