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

Abstract

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.