New Material Characterization method by Using a pulsed Neutron Transmission Spectroscopic Radiography

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Spectroscopic neutron radiography using a pulsed neutron can give structural information of materials since it has neutron cross section data at each pixel. Especially, at low energy region of the cross section Bragg edges appear which reflect the crystal structure of the materials. The shift of the Bragg position gives strain of the crystal. We performed the experiment on the iron sample which would have strain due to bending. We could clearly observe the strain position and amount of the strain. It was found that the strain appeared on specific crystal planes. It is also indicated that the total neutron cross section around the Bragg edge depended on the grain size of the crystalitte and showed that the cross section decreased proportional to the grain size by a model experiment. Furthermore, the crystal structural change around the welded position of the SS-Iron sample and Iron-Iron sample. The crystal structure change had similar tendency in both sample. Naturally, far from the wel … More d position the cross section showed the typical feature of Bragg edges of iron and SS, as approaching the weld position the edge became sharper, and at weld position the edge had a sharp edge implying the isotropic distribution of the crystallittes. On the other hand, at high energy we can utilize the resonance absorption to get image of elements or nuclei. We performed transmission measurement of the heavy material to get CT image, and it is suggested that the method was also useful for imaging the element distribution and also that we may use this to measure the temperature by analyzing the resonance peak. We developed the sensor of the imaging detector based on Gd composite. We succeeded in making a test detector and also obtained images by using the neutron beam.As mentioned above, the spectroscopic neutron imaging using the pulsed neutron sources are very powerful tool to investigate micro structure of the materials, such as strain, crystallite size, distribution of crystallite and so on. Now, the operation of the big proton accelerator neutron source is just about to take place. We will get much higher quality data by using such high intensity sources and also get much detailed information about the sample materials. Therefore, we are now on the stage to develop the method further to promote the industrial applications. Less