Plastic scintillators offer fast response and ease of scale-up. However, their scintillation light yield (LY) is up to approximately 10,000 photons/MeV, which is much lower than that of widely used inorganic scintillators. In this study, we aimed to improve the LY by using 9,9-dimethylfluorene (MF), which has a smaller gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) than commonly used polymer hosts such as polystyrene (PS) and polyvinyl toluene, as part of the host material in plastic scintillators. By optimizing the mass ratio of PS to MF and the concentration of butyl-PBD, the LY reached a maximum of 13,300 photons/MeV at a butyl-PBD concentration of 0.3 wt% and a PS:MF ratio of 68:30, which is approximately 1.3 times that of the commercially available EJ-212 (LY: 10,000 photons/MeV). Furthermore, the scintillation decay time constants (τs) of the first component in MF-containing plastic scintillators were 1.1−1.4 ns, which is comparable to that of the commercially available EJ-228 (τ: 1.4 ns). • We developed plastic scintillators containing 9,9-dimethylfluorene. • We investigated the optimal 9,9-dimethylfluorene concentration. • The scintillation light yield of 13,300 photons/MeV was achieved.
Kanenari et al. (Fri,) studied this question.