Inorganic scintillator crystals used for nuclear security applications typically have a large refractive index which tends to trap, via total internal reflection, much of the light they produce. Photia Inc., in collaboration with its industry partner Alpha Spectra Inc. and partners at Lawrence Berkeley National Laboratory (LBNL), will develop nanostructured coatings to enhance light extraction from scintillator crystals used in radiation detectors. These coatings will use two-dimensional and three-dimensional photonic crystals to reduce internal reflections at the surface of the scintillator which is coupled to the photodetector system. Manufacturing with interference lithography will allow for large scale production of light extraction coatings, which increases the utility of their application in commercial radiation detectors. Briefly, the proposed research in Phase 1 consists of the following tasks. Mathematical modeling techniques will be used to determine the photonic crystal patterns which are most promising for enhancing light extraction. Light extraction coatings will be manufactured with interference lithography and tested in conditions which simulate a scintillator crystal. Utilizing insight from modeling and experiment, optimally designed light extraction coatings will be manufactured and delivered to collaborators at LBNL and Alpha Spectra Inc. for testing in scintillation detector systems. The overall light extraction efficiency and energy resolution will be compared with traditional coupling methods.
