Zinc Oxide Nanowire Gamma-Ray Detector with High Spatiotemporal Resolution
Mayo, Daniel Craig
This research is focused on developing a new type of gamma-ray scintillator and is motivated by the need for more accurate positron emission tomography (PET) imaging. PET scans are used to display regions of high-metabolic activity within the body and can indicate the presence of tumors, so clear images are essential for accurate diagnoses and treatment options. Scintillation detectors currently used for PET scans typically have a time resolution of hundreds of ps that yields images with poorly defined and blurred boundaries. Conversely, ZnO nanowires have a response time that is an order of magnitude faster with the potential for an analogous improvement to spatial resolution. Moreover, initial experiments show ZnO nanowires are radiation hardened with highly transient lattice defects. To optimize overall scintillator efficiency, the emission can be enhanced through a combination of optical-cavity effects (15x enhancement) and plasmon-exciton coupling (3x enhancement), while the low interaction volume of the nanowires can be addressed by adding a high-Z backing layer to attenuate incoming gamma rays. The ability to decouple, and address separately, emission efficiency and gamma-ray interaction provides a unique materials workbench and establishes ZnO nanowires as a highly promising PET scan scintillator material.