Position Sensitivity and Gamma-ray Separation of a Plastic Scintillator for a Neutron Camera Based on Electric Collimation

摘要

We are currently developing a proof-of-principle neutron camera based on electric collimation which consists of two detectors, with each arrayed by five plastic scintillating rods with dimensions of 1 × 1 × 10 cm~3 for the purpose of imaging neutrons. The imaging principle of such a neutron camera is quite different from that of neutron radiography based on neutron absorption. In this case, the image resolution of a neutron camera is sensitive to the uncertainty in the interaction position and the gamma-ray background. To determine the interaction position, we made use of the center of gravity in charge signals generated from photomultiplier tubes attached to both ends of the rod. The interaction positions were related to the intensity of scintillation light output at one end of the rod, decreasing due to the attenuation effect with moving away from the position at which the scintillation light output was generated. In order to improve the image resolution, we tried to separate gamma rays from neutrons by using the time-of-flight method.