Utilization Of Periodic Nanostructures To Improve Detection Efficiency And Time/Energy Resolution Of Inorganic Scintillators

Inorganic scintillators are commonly used in various radiation detection applications due to their excellent energy resolution, reliable performance, relatively low cost, and high detection efficiency. However, many inorganic scintillators have high refractive indices and experience significant light losses at the collection surface caused by total internal reflection (TIR). This project employs optimized periodic nanostructures, known as photonic crystals (PHCs), to recover some of the light losses. A PHC layer creates an improved optical pathway between the scintillator and the photosensor for the trapped photons through constructive light interference. Enhancing the light extraction from an inorganic scintillator improves its energy resolution, time resolution, and the overall detection efficiency. In this work, the effects of an optimized PHC coupling with a LYSO scintillator are experimentally demonstrated. The PHC geometry is optimized through tailored simulations, manufactured with electron beam lithography, and characterized with radiation measurements to quantify improvements in light output and energy resolution. A 10 x 10 x 3 mm³ LYSO sample shows an improvement of 28% in light output and 13% in energy resolution with an optimized 2D block structure Si₃N₄ PHC structure. Future work will focus on expanding the experimental framework to other inorganic scintillators such as NaI and LaBr₃, which are expected to have even greater light output improvements owing to their higher refractive index and total internal reflection.