Measurements of 73-keV X-ray time spectrum with avalanche-photodiode scintillation detector using Bi₂O₃-nanoparticle-doped plastic scintillator

Time spectra of 73-keV X-rays were successfully observed with a scintillation detector using a Bi₂O₃-nanoparticle-doped plastic scintillator (PLS) and silicon avalanche photodiode (Si-APD). A 5 wt% Bi₂O₃-nanoparticle-doped PLS was fabricated and cut out to be ∼3.0×3.0 mm and 0.9 mm thick, and it was mounted on a Si-APD operating in proportional mode. An organic scintillator of [2-(4-tert-butylphenyl)-5-(4-phenylphenyl)]-1,3,4-oxadiazole was used for the PLS by 1.68 mol% of polystyrene solvent. When the PLS and Si-APD were cooled to −30° C, a good time resolution of 0.35 ns (full width at half maximum) was obtained for 73.04-keV X-rays when measuring a time structure of the multibunch mode in synchrotron ring operation. The Si-APD scintillation detector mounting a Bi₂O₃-nanoparticle-doped PLS can be applied well to research fields that need both a high detection efficiency and a subnanosecond time resolution with a photon energy of more than 70 keV, such as synchrotron radiation nuclear resonant scattering on ¹⁹³Ir.