Melt Blending: A Tool to Simplify Plastic Scintillator Synthesis

Abstract

Plastic scintillators are widely used as radiation detection media in homeland security and nuclear physics applications. Their attributes include low cost, scalability to large detector volumes, and additive compounding to enable additional material and detection features, such as pulse shape discrimination (PSD), gamma-ray spectroscopy, aging resistance and coincidence timing. However, traditional chemically cured plastic scintillators (CCS) require long reaction times, and hazardous wet chemical procedures performed by specially trained personnel, and can leave residual monomer, resulting in deleterious optical and material properties. Here, we synthesize melt blended scintillators (MBSs) in 2.5 days using easily accessible solid state compounding of commercially-available poly(styrene) with 30-60 wt. % fluorene-based compound ‘P2’ to create monolithic detectors with < 100 ppm residual monomer, in several form factors. The best scintillation performance was recorded for 60 % P2 in Styron 665, including gamma-ray light yield 139 % of EJ-200 commercial scintillator and PSD figure of merit (FOM) value of 2.65 at 478 keVee, approaching P2 OGS. The applicability of MBS to generate fog-resistant scintillators and PMMA-based scintillators for use in challenging environments is also demonstrated.