Polymerizable dopants capable of high light output and pulse shape discrimination for application in plastic scintillators

Abstract

Scintillators have long been established for radiation detection and even date back to 1917 in which the use of a scintillator led to the discovery of the proton. Of particular interest are plastic scintillators (PS) which are low cost plastics doped with organic fluorescent compounds. In addition, PSs are of great interest due to their light weight, ambient stability, and ease of fabrication into complex and large geometries. Recent interest in PSs has become even more widespread due to their pulse shape discrimination (PSD) capabilities – the ability to detect and discriminate neutron (n) signals in gamma () radiation background. This is achieved by simply over doping 2,5-diphenyloxazole (PPO) in poly(vinyltoluene) matrices. However, over-doping PPO causes mechanical softening of the plastic, hindering its field deployment and overall widespread commercialization. It has also been observed that the dopant leaches out of the matrix which can reduce PSD capabilities and scintillator lifetimes. In an effort to improve current PSs, this project aims to enhance the mechanical and optical properties of PSs by co-polymerizing PPO designed monomers into a polymer matrix. To the best of our knowledge, the PPO monomers designed and synthesized as primary polymerizable dopants are reported here for the first time. Co-polymerizing PPO monomers into the matrix have proven to increase mechanical and thermal stability and have reached high loadings without the leaching of dopants to their surroundings. In addition, they have displayed high light outputs and great PSD adequate for n/ discrimination.