High-Performance Transparent Optical Ceramic Scintillators through Nanotechnology

描述（由申请人提供）：LSO通常被认为是PET的理想闪烁体。它对511 keV的伽马射线有很高的阻止能力，超过20000光子/MeV的高光产额，以及32 ns的快速衰减。它实现了高的符合时间分辨率和能量分辨率。但是LSO的单晶生长困难且昂贵，再现性差，并且该材料根本无法用于一般商业用途。为了克服这些缺点，我们在以前的工作中开发了一种半透明的LSO光学陶瓷，其闪烁性能与单晶相当，但更容易制造，可以以更低的成本填补可用性空白。但由于LSO是光学各向异性的，它不能通过传统的陶瓷技术完全透明。然而，最近通过纳米技术开发了一种新工艺，该工艺能够在甚至光学各向异性材料的陶瓷中实现几乎完全透明。该技术涉及在限制最终晶粒尺寸低于可见光波长的条件下固结纳米粉末，从而防止几乎所有散射并使材料完全透明。该过程已完全证实在多晶氧化铝，这是类似的各向异性的实验，并正在开发的光学窗口应用。该建议的目的是将两种已经开发的技术联合收割机结合起来，以生产完全透明的光学陶瓷形式的LSO，其显示出与单晶相当的闪烁性能。在第一阶段，我们将确认已经建立的氧化铝工艺也适用于LSO。我们将建立技术来制造必要的纳米颗粒粉末，并确定固结条件下，可以实现所需的材料性能。

DESCRIPTION (provided by applicant): LSO is generally recognized as the ideal scintillator for PET. It has high stopping power for 511 keV gamma rays, high light yield of over 20000 photons/MeV, and rapid decay of 32 ns. It achieves high coincidence timing resolution and energy resolution. But single crystals of LSO are difficult and expensive to grow, reproducibility is poor, and the material is simply not available for general commercial use. To overcome these drawbacks, we have in our previous work developed a translucent LSO optical ceramic, which displays scintillation performance comparable to that of the single crystal, yet is easier to fabricate and could fill the availability gap at lower cost. But because LSO is optically anisotropic, it cannot be made fully transparent by conventional ceramic technology. Recently, however, a new process has been developed through nanotechnology that is capable of achieving virtually full transparency in ceramics of even optically anisotropic materials. The technique involves the consolidation of nanopowders under conditions that limit the ultimate grain sizes to below the wavelengths of visible light, thereby preventing virtually all scattering and rendering the material fully transparent. The procedure has been completely confirmed in experiments on polycrystalline alumina, which is similarly anisotropic, and is being developed for optical window applications. It is the aim of this proposal to combine the two already developed technologies so as to produce LSO in the form of a fully transparent optical ceramic, which displays scintillation performance comparable to that of a single crystal. In Phase I we will confirm that the process that has already been established for alumina is adaptable to LSO as well. We will establish techniques to fabricate the necessary nanoparticulate powders and to define the consolidation conditions under which the desired material properties can be achieved.