Highly Luminous Scintillating Nanocomposites Enable Ultrafast Time Coincidence Resolution for γ‐rays Detection with Heterostructured Multilayer Scintillators

Abstract Brighter fast scintillators are needed for advanced applications to acquire data with high signal‐to‐noise ratio in short time windows, like in the time‐of‐flight positron emission tomography (ToF‐PET) imaging technique for cancer. A new composite polymeric fast scintillator loaded with high‐density hafnium dioxide (HfO 2 , hafnia) nanoparticles is developed here to be used for detection of the 511 keV γ‐rays employed in ToF‐PET. By a fine tuning and engineering of the electronic properties of its components, namely the polymeric matrix, the dense nanoparticles and the embedded fluorescent dye, a highly luminous polymeric scintillating nanocomposite is realized, showing an unprecedented scintillation efficiency for plastic materials and nanosecond‐scaled scintillation decay. Nanocomposite films are then coupled to dense bismuth germanate (Bi 4 Ge 3 O 12 , BGO) crystal sheets to fabricate an heterostructured multilayer scintillator as a prototype pixel for ToF‐PET scanners. Thanks to the nanocomposite high scintillation efficiency, the prototype detector shows an ultrafast time resolution of 115 ps for 511 keV γ‐rays detection, actually limited by the non‐optimal light transport properties in the pixel and by the sensitivity of the employed photodetector.