The most common ionizing radiation detectors using inorganic solid scintillators do not currently enable the technological progress in the fields of high-energy particles detection and medical diagnosis (such as in time-of-flight PET tomography), where high light yield and fast timing capabilities are needed. Nanoparticles can be exploited as scintillators to overcome these limits due to the possibility to control and modify their structural and luminescence properties. Moreover, nanoparticles can be embedded in polymers for the fabrication of nanocomposites with high optical transparency.<br/>The main goal of the project is to develop advanced hafnium oxide nanocomposite scintillators with time response in nanoseconds, while exploiting the hafnia quality to efficiently stop the ionizing radiation. In order to reach the project goal, the radioluminescence properties of inorganic hafnia nanoparticles will be optimized by defects engineering and doping strategies. The hafnia surfaces will be decorated with highly fluorescent organic dyes and the radioluminescence of nanoparticles will sensitize the dye emission. These hybrid nanoscintillators will be embedded in a polymer matrix in order to fabricate low cost, flexible and scalable nanocomposite scintillators with optimized luminescence efficiency and fast time response. <br/>The project is at the forefront of the progress in high-energy physics experiments to minimize the photons losses at high count rates, and meets the urgent demands of medical imaging techniques to gain high quality images. The results of the proposed research will represent a fundamental step forward towards significant advances in technologies for ionizing radiation detection as well as reinforce the position of the European scintillation community worldwide.