NEUTRON/GAMMA RAY DISCRIMINATION METHOD OF SCINTILLATION NEUTRON DETECTOR USING ZnS PHOSPHOR

摘要

PROBLEM TO BE SOLVED: To reduce the gamma ray sensitivity while keeping the counting rate performance for the neutron image detector using ZnS phosphor.;SOLUTION: ZnS:Ag/⁶LiF neutron detection sheet as a scintillator for neutron is used, in back of the detection sheet, a bundle of 64 lines of wavelength shift fibers are placed and under that the 64 lines of wavelength shift fibers are perpendicularly arranged for forming the bundles of longitudinal axis and the lateral axis. The bundles of wavelength shift fibers are respectively connected with the 64 channel photomultipliers. The signals output from the multi-anode photomultipliers are amplified to ten times with the high speed amplifier and the pulse height discriminator and pulse height discriminated. After that, if it is determined by using the circuit constituted of an AND circuit, gate time generation circuit, gate circuit, and OR circuit, that the signal is recognized as the gamma rays, the neutron signals are made invalid. Even in this case, if at least one signal between the X and Y output signals is counted within the prescribed gate time, it is counted as the neutron signals.;COPYRIGHT: (C)2008,JPO&INPIT