抄録
We present neutron imaging of water in root-soil system by an X-ray film method as well as CT method. In the case of an X-ray film method, a soybean seedling grown in a thin aluminum container was fixed on an aluminum cassette and was irradiated for 19 seconds by thermal neutrons from a research reactor, JRR-3M, installed at Japan Atomic Energy Research Institute. The neutron flux from the reactor was 1.5X 108n/cm2・s. A gadolinium n/γ converter, which thickness was 25μm, and an X-ray film were sealed in vacuum in the cassette. To get a CT image, the soybean seedling grown in a cylindrical container was fixed on a rotating disk and was irradiated for 4 seconds per projection. The neutrons penetrating the sample was converted to photons by a fluorescence converter. The photon image was guided to a cooled CCD camera using two mirrors. The sample was rotated with an interval of 1 degree for 180 degree, i.e.180 images were obtained for the CT construction. Neutron beams allowed to image not only a root imbedded in soil but also water movement in the vicinity of the root. The method is nondestructive, therefore, morphological development of the root but also water movement near the root was able to be visualized. Through piling up the CT images, which were successively taken every 50μm, three dimensional water image of the root-soil system was constructed.
