Plasmonic ultraviolet filter for fast-timing applications.

Barium fluoride, an inorganic scintillation material used for the detection of X-ray and/or gamma-ray radiation, has been receiving increasing attention in the field of radiation measurements in fast-timing applications. To make full use of its timing properties, its slow emission around the ultraviolet region, more specifically, the 300 nm region needs to be suppressed. Although doping ions, such as lanthanum, yttrium, and cadmium, can suppress the slow component, such techniques can lose information of interacted radiations. Consequently, a suppression technique that does not suffer from information loss while maintaining precise timing measurements would be desirable. In this study, we proposed aluminum nano-disk-based plasmonic filters to suppress slow emissions while maintaining fast emissions around 195 and 220 nm and a usability of the slow component. Finite-difference time-domain simulations and experimental results exhibited good agreement, with over 90% of slow components being adequately suppressed without sacrificing fast components, proving that aluminum nanodisks can be used for ultraviolet filters. Moreover, based on the designed filter performance, we conducted coincidence time resolution simulations for positron-electron annihilation gamma rays from an analytical perspective. The simulations indicated the designed filters could maintain high timing performance. Consequently, the proposed plasmonic ultraviolet filter was suitable for maximizing the potential of barium fluoride scintillators.