Neutron phase imaging by a Talbot-Lau interferometer at Kyoto University Reactor

We have developed a new neutron phase imaging system with a Talbot-Lau interferometer for utilization at the CN-3 port of the Kyoto University Reactor. To achieve efficient differential-phase imaging and visibility (dark-field) imaging at this beamline, we adopted a relatively shorter design wavelength of 2.7 Å. By fabricating neutron absorption gratings with thick gadolinium absorbers, we were able to obtain clear moiré fringes with a high visibility of 55% for thermal neutrons. As a demonstration of its imaging capabilities for expanded actual utilization in the medium-sized sources, we observed additively manufactured rods of Inconel 718. Using visibility imaging, we successfully examined variations in the size of defects in the rods caused by hot isostatic pressing process. In addition, we conducted tomography measurements of the rods, which allowed us to reveal the spatial distribution of defects at sub-micrometer scales.