LiF crystals as high spatial resolution neutron imaging detectors

Matsubayashi, Masahito  ; Faenov, A. Ya.*; Pikuz, T.*; Fukuda, Yuji; Kato, Yoshiaki* ; Yasuda, Ryo; Iikura, Hiroshi  ; Nojima, Takehiro; Sakai, Takuro

Neutron imaging by color center formation in LiF crystals was applied to standard samples such as a sensitivity indicator (SI) for neutron radiography. The SI was exposed to 5 mm pinhole collimated thermal neutron beam with a LiF crystal and a neutron imaging plate (NIP) for 120 min in JRR-3 thermal neutron radiography facility. The image in NIP was read out with a readout resolution of 50 m. The image of SI in LiF crystal was read out with pixel size of 1.38 m using a laser confocal microscope. All gaps were clearly observed in the images for both LiF crystal and NIP, but small holes were not recognized for NIP. The experiment showed that LiF crystals had excellent characteristics as neutron imaging detectors such as high sensitivity, high spatial resolution, wide dynamic range and so on. In the paper, detailed characteristics of LiF crystals are compared with those of other neutron imaging detectors: NIP, a combination of fluorescent converter and cooled CCD camera.