Photoluminescence and scintillation characteristics of Bi-loaded PVK-based plastic scintillators for the high counting-rate measurement of high-energy X-rays.

We synthesized Bi-loaded poly(9-vinylcarbazole) (PVK)-based plastic scintillators for high-energy X-ray detection. PVK, triphenylbismuth (BiPh3), and 1,4-bis(2-methylstyryl)benzene (bis-MSB) served as the host polymer, heavy metal compound, and organic phosphor, respectively. The emission peaks at approximately 440 nm in the photoluminescence emission and X-ray-excited radioluminescence spectra of the synthesized scintillators are attributed to bis-MSB. The scintillation decay time constants of the 1st exponential components are 1.6 ns. The presence of BiPh3 in the synthesized scintillators successfully enhanced their efficiency in the detection of 67.41 keV X-rays. The detection efficiency per 1 mm thickness achieved by a PVK-based plastic scintillator loaded with 10 wt% Bi was 2.5-times higher than that achieved by a commercial polyvinyltoluene (PVT)-based plastic scintillator loaded with 5 wt% Pb, EJ-256. The light yield of the PVK-based plastic scintillator loaded with 10 wt% Bi was 5600 photons per MeV, which was higher than that of EJ-256. We successfully enhanced the high-energy X-ray detection efficiency of PVK-based plastic scintillators, through the addition of BiPh3, while maintaining a short decay time of nanoseconds.