NGn Prototype Neutron Detector Development Using Cosmic Muons*

The MoNA (Modular Neutron Array) collaboration studies the properties of exotic neutron-rich nuclei using an array of 288 plastic scintillator neutron detectors. In order to increase neutron detection resolution for higher mass systems at FRIB, the MoNA collaboration is developing a next-generation neutron detector (NGn) array designed to have ~1 cm position resolution. The proposed design uses 128 large scintillator tiles, each equipped with 64 silicon photomultipliers (SiPM), to detect the scintillation light. We developed prototype detectors with an array of 16 SiPMs to optimize the balance between light detection efficiency and position resolution for the detector's response to cosmic muons. We developed an algorithm to determine the location of scintillation events in the plate using the positions and signal strengths of all active SiPM detectors. We made a series of measurements for several different detector configurations to compare with simulation. Significant differences between the two point to a need for improvement in simulation. The position reconstruction of our algorithm is effective but limited; edge effects and variations in plate efficiency could be addressed through the development of a machine learning-based algorithm.