Selective enhancement of the fast component in barium fluoride scintillators using multilayer close-packed nanosphere-assembled photonic crystals.

Barium fluoride (BaF2) scintillators have garnered widespread application in high-energy physics, due to their ultrafast scintillation component peaking at 220 nm. Nevertheless, their slow scintillation component with much higher light yield limits their performance in ultrafast detection scenarios. While existing methods like rare-earth ion doping or pressure control can partially suppress the slow component, the fast component should be enhanced to further improve the performance. In this study, we propose a photonic crystal structure composed of multilayer close-packed SiO2 nanospheres to selectively enhance the fast component of BaF2 scintillators by selectively coupling with the fast component via surface lattice resonances and diffraction effects. A periodicity of 200 nm and 7 layers of SiO2 nanospheres are designed and fabricated, leading to an average enhancement ratio of 1.59 (maximum 1.79) for the fast component, without affecting the slow component. Compared with our previous work on selectively enhancing the fast component of BaF2 using photonic crystal structures, the multilayer nanosphere structure proposed in this paper effectively improves the coupling efficiency between scintillation light and the nanostructure by the increased structural thickness, thus achieving a better selective enhancement effect.