SBIR/STTR Award attributes
Novel detector technologies that can provide 300 μm or better spatial resolution with gamma rejection better than 10-6 are needed to enable efficient measurement of small single crystals for diffraction and diffuse scattering measurements. Currently used GS20 glass scintillator works well but cannot provide the desired resolution performance due to its low brightness. A bright, fast, high spatial resolution scintillator will improve the spatial resolution and throughput of the single crystal diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory. We propose to address the limitations of GS20 by using an advanced scintillator, made in a large area, microcolumnar film format that heretofore was not possible to grow because of the extreme hygroscopic nature of the material. This choice is based on the known high brightness of the material, which emits a relatively low number of photons/MeV gamma, but is expected to yield as many as 50,000 to 100,000 photons per thermal neutron interaction, a factor ~8 to 16 times higher yield than current GS20 glass. The high thermal neutron efficiency of this material implies that only ~1.0 mm of scintillator thickness is needed to absorb about 60% of 1Å neutrons. The very thinness of the scintillator helps significantly in discriminating against gammas by minimizing the probability of both photoelectric absorption and light conversion efficiency for gammas. Finally, one of the key innovative approaches we plan to pursue is to realize large-area scintillators. In the Phase I, RMD Inc. used physical vapor deposition to make screens of scintillation material, as well as dope or co-dope the material with divalent or trivalent ions to improve the speed. The entire deposition and sealing process was carried out in a moisture free atmosphere using a newly developed technique at RMD. The spatial resolution for neutrons was estimated as less than 300 µm, with better than 1x10-6 gamma rejection, and 60% neutron absorption efficiency. In the Phase II, RMD Inc. will maximize the light output by optimizing the dopant concentration, and scale- up deposition to large sizes. Additionally, we will protect the scintillator from moisture using a unique conformal coating, and a new type of hermetic sealing. The efficacy of the scintillator will be demonstrated at ORNL with less than 300 µm spatial resolution when coupled to the detector, ~1x10-7 gamma rejection and 60% neutron absorption efficiency for a 1 mm thick scintillator screen. The scintillator will be coupled to the existing pixelated readout and the detector will be delivered to ORNL for immediate use. RMD’s scintillator/detector will be an excellent choice for neutron detectors for any facility that runs neutron experiments. For example, at Oak Ridge National Laboratory, large-area detectors at the Spallation Neutron Source are used for neutron scattering experiments and in materials research for a variety of applications. Including the U.S. facilities, there are 45 neutron research centers located around the world that will want to take advantage of our technology.
