High-position-resolution scintillation neutron-imaging detector by crossed-fiber readout with novel centroid-finding method

Aiming at high-position-resolution and high-counting-rate neutron imaging, a novel centroid-finding method is proposed for a scintillation neutron-imaging detector with crossed-fiber readout. Crossed wavelength-shifting fibers are arranged on and under the scintillator. Luminescences generated in the scintillator are emitted and detected by a few fibers surrounding the incident point of a neutron. In the novel method, X and Y positions of the incident neutron are decided by coincidence of a central signal and neighboring signals, respectively. By fundamental experiments using a ZnS:Ag/6LiF scintillator of 0.5-mm thickness and crossed wavelength-shifting fibers with a size of 0.5×0.5 mm2, it was confirmed that the position resolution is about 0.5 mm and the limitation of the neutron-counting rate is 320 kcps.