Neutron Imaging Device Using Wave Length Shifting Fibre Technique

A high resolution imaging device for cold neutrons detection has been constructed for the neutron optics (nop) Group in RIKEN, and tested with thermal neutrons at the Laue-Langevin Institute in Grenoble. It consists of a thin plate of ZnS(Ag)+6LiF scintillator optically coupled with Y11(400) wave-length shifting (WLS) fibres. The space resolution was found to be ~ 0.45 mm in FWHM as expected from the pitch of WLS fibres with a crossection of 0.4 ´ 0.4 mm2. The detection efficiency for thermal neutrons (l = 2.5 ) was estimated with respect to 3He monitor, and found to be ~ 10 %, which ensured a reasonable efficiency for cold neutrons (l = 10 ).