Fig. 10-7 Schematic view of the high-resolution static imaging system Neutrons that transit an object are converted into visible light with an intensity dependent on the intensity of the neutrons. The projection image, composed of visible light on a fluorescent converter, is reflected by the first mirror and the second mirror and finally formed on the CCD (charge coupled device) chip through a lens. The CCD chip used in this system has an imaging area of 1000 x 1018 pixels. Captured image data are digitized by a 14 bit A/D (analog to digital) converter and transferred to a personal computer as digital data.

Fig. 10-8 Projection image of a cigarette lighter This is a projection image of a cigarette lighter captured by a high-resolution static imaging system. The CCD chip is highly sensitive to radiation. When pixels are hit by radiation, white spots were observed on the original image. This image was processed using a noise removal program developed for this system so that white spots are corrected. Although saved images on the computer are 14 bit digital images, this image was displayed as an 8 bit gray-scale image.

A neutron radiography technique is being developed that allows nondestructive visualization of objects within a container. It uses a high-intensity neutron beam drawn from the JRR-3 (Japan Research Reactor No.3). Attenuation of x-rays in a material depends on the density of orbital electrons in the material. Attenuation of neutrons in a material depends on the interaction between neutrons and the nuclei of the material. This means that neutrons can provide information about objects that is not provided by x-rays. We are seeking an imaging system with higher spatial and temporal resolution for the JRR-3 neutron radiography facility. In the development of imaging with improved spatial resolution, a system with a resolution less than 100 micrometer, using a cooled CCD camera system, is already available. In the development of high temporal resolution, we are configuring an imaging system in which a speed of 4,500 frames per second in full frame condition is available. This system will be used to clarify the mechanisms of fluid phenomena under extreme physical conditions.

Reference M. Matsubayashi et al., High Resolution Static Imaging System using a Cooled CCD Camera, Proc. 2nd Int. Top. Meet. on Neutron Radiography System Design and Characterization, Shonan Village Center/Rikkyo Univ. Nov.12-18, 242 (1995).

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