Patent ID: 7326933

Claim:
A two-dimensional radiation or neutron image detector which detects radiation or neutron comprising: a scintillator or phosphor as a detection medium and a wavelength shifting fiber as a constituent material, wherein the scintillator or phosphor as the detection medium is underlaid with a parallel array of wavelength shifting fibers having sensitivity to the fluorescence emitted from either detection medium and which can absorb the fluorescence with an efficiency of no more than 50%, said parallel array of the wavelength sifting fibers being backed with a parallel array of lateral side light detecting optical fibers such that the two parallel arrays of fibers are crossed at right angles, wherein position pulse signals for horizontal and vertical axes as obtained from the two parallel arrays of fibers are subjected to coincidence counting to determine two-dimensional incident position of radiation or neutron detected, and wherein the lateral side light detecting optical fibers have a square cross section with a length of 0.25 mm to 2 mm on each side such that one of the four lateral sides is scrapped off by a thickness of 20 μm to 50 μm over a length ranging from 1 cm to 20 cm, with a material capable of random reflection of light being provided on the lateral side of each optical fiber which is opposite to the scrapped side, the lateral side light detecting optical fibers being used to detect the fluorescence from the detection medium, thereby detecting radiation or neutron.