Images obtained by neutron transmission measurement using time-of-flight method

Neutron radiography using a pulsed neutron source can give transmission spectra that reflect the structure of the neutron cross-section of the object. At low-energy region, we can see Bragg cutoff, whose position and shape depend on the material. We have developed a new detector to observe such features of the transmission spectra efficiently. We used Li-glass pieces to achieve a high-count rate. The pixel size of the detector is not so good, about 1.7 mm×1.7 mm, but the maximum count rate is very high, about 0.24 M cps/pixel. We performed a transmission experiment of the welded piece of stainless steel to examine the usefulness of the detector and also the time-of-flight transmission method at a relatively low intensity spallation source, KENS. From the difference of Bragg cutoff of the transmission spectra, we could determine the welded position, which could not be recognized with the naked eye. This suggests the possibility of observation of lattice deformation in a welded place.