First Measurements with a Portable Pixelated Fast-Neutron Imaging Panel*

This work reports the design, construction, and results from initial measurements of a pixelated fast-neutron imaging panel recently constructed at Oak Ridge National Laboratory. The fast timing, pulse counting panel is suitable for associated-particle imaging (API). The panel is intended to be capable of both transmission and induced reaction imaging, allowing for a full 3-dimensional density map of an object without requiring 360° access. Unlike the current generation of API-based neutron imaging systems, this panel is intended to be field deployable. The panel is composed of an array of optically-isolated pulse-shape discriminating plastic scintillator pixels which are optically coupled to an array of position sensitive photomultiplier tubes in a hand-carryable package. Each quadrant of the panel is read out with a resistive charge-division network allowing it to be read out with only 4 channels that preserve the average position of detected light. This provides the fast timing and modest spatial resolution required for high-quality images.