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Isegawa, Kazuhisa; Setoyama, Daigo*; Higuchi, Yuki*; Matsumoto, Yoshihiro*; Nagai, Yasutaka*; Shinohara, Takenao
Nuclear Instruments and Methods in Physics Research A, 1040, p.167260_1 - 167260_10, 2022/10
Times Cited Count：1 Percentile：49.42(Instruments & Instrumentation)
Al
GaO
:Ce single-crystal scintillator to neutron radiographyIsegawa, Kazuhisa; Setoyama, Daigo*; Kimura, Hidehiko*; Shinohara, Takenao
Journal of Imaging (Internet), 7(11), p.232_1 - 232_9, 2021/11
Neutron radiography is regarded as complementary to X-ray radiography in terms of transmittance through materials, but its spatial resolution is still insufficient. In order to achieve higher resolution in neutron imaging, several approaches have been adopted such as optical magnification and event centroiding, and the authors focused on modification of the scintillator in this paper. A GdAlGaO:Ce single-crystal scintillator was applied to neutron radiography for the first time and was achieved a spatial resolution of 10.5 micrometers. The results indicate that this material can be a powerful candidate for a new neutron scintillator providing a resolution in micrometer order by optimizing the optical system and increasing the scintillator luminosity.
Higuchi, Yuki*; Setoyama, Daigo*; Isegawa, Kazuhisa; Tsuchikawa, Yusuke; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Nagai, Yasutaka*
Physical Chemistry Chemical Physics, 23(2), p.1062 - 1071, 2021/01
Times Cited Count：5 Percentile：56.1(Chemistry, Physical)This study is the first report on liquid water and ice imaging conducted at a pulsed spallation neutron source facility. Neutron imaging can be utilised to visualise the water distribution inside polymer electrolyte fuel cells (PEFCs). Particularly, energy-resolved neutron imaging is a methodology capable of distinguishing between liquid water and ice, and is effective for investigating ice formation in PEFCs operating in a subfreezing environment. The distinction principle is based on the fact that the cross sections of liquid water and ice differ from each other at low neutron energies. In order to quantitatively observe transient freezing and thawing phenomena in a multiphase mixture (gas/liquid/solid) within real PEFCs with high spatial resolution, a pulsed neutron beam with both high intensity and wide energy range is most appropriate. In the validation study of the present work, we used water sealed in narrow capillary tubes to simulate the flow channels of a PEFC, and a pulsed neutron beam was applied to distinguish ice, liquid water and super-cooled water, and to clarify freezing and thawing phenomena of the water within the capillary tubes. Moreover, we have enabled the observation of liquid water/ice distributions in a large field of view (300 mm 
300 mm) by manufacturing a sub-zero environment chamber that can be cooled down to -30
C, as a step towards 
visualisation of full-size fuel cells.
