Large Plastic Scintillation Detectors for the Nuclear

Future measurements with the Nuclear Materials Identification System require large, on the order of one meter by one meter, detectors for increased sensitivity. As the container to be interrogated or the distance gets larger, increased detector size is required for increased sensitivity. Large liquid and fast plastic scintillation detectors are being designed to meet experiment requirements. Large scintillation detectors present challenges for the optimization of light collection efficiency and uniformity. Design variables that affect light collection include, but are not limited to, (1) photomultiplier size, number and placement, (2) scintillator length, thickness, and light attenuation length, and (3) reflective coating reflection coefficient of scintillator walls. We have calculated light collection efficiency and uniformity for fast plastic detectors using two codes for modeling the optical properties of scintillators. Based on these calculations, we have completed our design and acquired a large plastic detectors for testing