Optimization Of Plastic Scintillators With Pulse-shape Discrimination Capabilities

Plastic scintillators have recently reemerged as promising candidates for the detection and discrimination of nuclear materials. Relative to single crystal scintillators, plastic scintillators are cheap and straightforward to produce. Relative to liquid scintillators, plastic scintillators are easy to handle, easy to contain, and couple well with solid-state photosensors. However, there are challenges in light output, physical properties, and long-term stability of plastic scintillators. We have optimized and studied plastics capable of pulse-shape discrimination (PSD) to improve scintillation performance, physical properties, and long-term stability of these materials. We have also explored the addition of organic salts of lithium-6 to plastic scintillators to enable discrimination of thermal neutrons, which posed new challenges in materials processing. Our efforts have allowed us to produce large-scale plastic scintillators (~ 0.5 m in length and larger). These plastics have great potential for any application that requires sensitivity to fast and/or thermal neutrons. These applications include multiplicity counting, neutron imaging, reactor antineutrino detection, and any system that currently uses PSD-capable liquid scintillators.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-819806.