High counting rate two-dimensional neutron-imaging method using rectangular scintillators with WLS fibers

A high counting rate two-dimensional neutron-imaging method using rectangular scintillators with wavelength-shifting (WLS) fibers has been developed for neutron-scattering experiments at a next-generation high-intensity pulsed-neutron source. Rectangular scintillators are arranged in longitudinal and transverse directions and WLS fibers are attached along four sides of these scintillators. Luminescences generated in the scintillator are absorbed by the four fibers and wavelength-shifted luminescences are detected by multi-channel photomultipliers. The position of an incident neutron is decided by coincidence of the four signals. By experiments using 5 mm×5 mm×2 mm-thickness 6Li glass scintillators and 0.5-mm square WLS fibers, it was confirmed that the maximum counting rate for each pixel was 3 Mcps with the coincidence time of 100 ns.