Development of a small-aperture slit system for a high collimator ratio at the thermal neutron radiography facility in JRR-3

Yasuda, Ryo; Nojima, Takehiro; Iikura, Hiroshi  ; Sakai, Takuro; Matsubayashi, Masahito  

A small aperture system was developed and installed to enhance collimator ratio / of the thermal neutron radiography facility (TNRF) in JRR-3. The small aperture system increases the / by making small aperture . Image sharpness was getting better with decreasing the aperture size below 10 mm by 10 mm in TNRF. The beam area of the small aperture slits was relatively small in comparison with that of the conventional large collimator, although gradually increasing with increasing the aperture size. Even 5 mm by 5 mm in aperture size, the practical beam area for imaging examinations corresponds to around 25 mm by 20 mm, which is enough area to carry out the high spatial resolution imaging.