Paper Scintillator Incorporated with Scintillator-Silica Fine Powders: Photophysical Characterization and Proof of...

In order to decrease the generation of radioactive waste, it is of interest to develop a scintillator capable of absorbing tritiated solutions for efficient detection of low-energy β-particles from tritium. In this work, paper scintillator incorporated with scintillator-silica fine powders (FPs), which is composed of scintillator-silica nanoparticles (NPs) attached to silica FP, was fabricated and evaluated. The scintillator-silica NPs contained liquid scintillators benzoic acid, 2,5-diphenyloxazole (PPO), and 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP). Photophysical characterization was executed by means of photoluminescence, fluorescence lifetime, quantum efficiency, and radioluminescence under X-ray excitation. POPOP emission was confirmed by absorbing the emissions from benzoic acid and PPO. Radioluminescence results confirmed POPOP emission. Fluorescence lifetime analysis yielded a 1.29 ± 0.01 ns main fast decay (64.2%) combined with a 4.00 ± 0.04 ns slower decay (35.8%). The combined luminescence results suggested that most POPOP in the paper scintillator was solvated. At 301 nm, the average quantum efficiency from both faces of the paper scintillator was about 4%, and at 370 nm, it was about 11%. The paper scintillator detected ³H β-particles by dipping the paper scintillator into tritiated water without a liquid scintillator. The counting efficiency depended on water content in the paper scintillator, and it increased to above 10% for tritium activity less than 200 dpm since it was preferentially adsorbed by vapor pressure isotopic effect and isotopic exchanged tritium on the surface of the scintillator-silica FP in the paper scintillator.