High-energy X-ray detection capabilities of Hf-loaded plastic scintillators synthesized by sol–gel method

The high-energy X-ray detection capabilities of hafnium oxide-doped organosilica plastic scintillators were analysed. Plastic scintillators with different concentrations of Hf were synthesized via the sol–gel method. In the photoluminescence emission spectra and X-ray-excited radioluminescence spectra, all of the plastic samples showed broad emission bands peaking between 350 and 500 nm derived from the fluorescence of the organic phosphor b-PBD. The maximum detection efficiency for a thickness of 1 mm towards 67.41 keV high-energy X-ray was estimated to be 6.3% (Hf 10 wt%) which is 3.7 times larger than that of the undoped sample and 1.9 times larger than that of the commercialized Pb 5 wt%-doped plastic scintillator EJ-256. The full width at half maximum time resolutions were estimated to be approximately 0.4 to 0.6 ns, which is almost independent of the Hf concentration of Hf. Therefore, the detection efficiency towards high-energy X-rays was successfully improved while maintaining the original high time resolution of plastic scintillators by adding Hf to the plastic scintillator at high concentrations.