SEARCH FOR ULTRA-FAST, HEAVY-ATOM SCINTILLATORS

这项研究的目的是发现新的制冷剂， 快速发射、高原子序数、高密度和高亮度。 具体地说，我们寻求一种闪烁体与尖峰检测 BGO的效率，BaF 2的时间分辨率， NaI（T1）。 我们的最终目标是大幅提高 正电子发射断层扫描仪，提供高的峰值效率 和良好的空间分辨率，飞行时间的优点 信息和良好的脉冲高度分辨率，用于散射抑制。 在 此外，单光子断层扫描和常规核医学 成像将受益于具有较高阻止能力的闪烁体 死时间比NaI（T1）小。 我们已经开发出一种方法，能够快速筛选数百个潜在的 化合物，而无需昂贵和耗时的生长步骤， 闪烁质量晶体。 该方法使用20-30的100 ps脉冲串 keV X射线从台式脉冲X射线发生器测量 任何荧光发射的强度、衰减时间和发射光谱 从粉末样品中。 我们还将进行分子轨道 计算预测候选物的闪烁特性 材料（掺杂和未掺杂的化合物），并使用这些理论 预测来指导我们的搜索。 最后，许多候选人 化合物（特别是掺杂的化合物）不是市售的， 所以我们会合成大量的化合物来测试。

The objective of this research is to discover new scintillators with very rapid emissions, high atomic number, high density, and high luminosity. Specifically, we seek a scintillator with the photopeak detection efficiency of BGO, the timing resolution of BaF2, and the luminosity of NaI(T1). Our ultimate goal is to improve substantially the capabilities of positron emission tomographs by providing high photopeak efficiency and good spatial resolution, the advantages of time-of-flight information, and good pulse height resolution for scatter rejection. In addition, single photon tomography and conventional nuclear medicine imaging would benefit from a scintillator having higher stopping power and less dead time than NaI(T1). We have developed a method able to rapidly screen hundreds of potential compounds without the costly and time-consuming step of growing scintillation quality crystals. This method uses 100 ps bursts of 20-30 keV X-rays from a table-top pulsed x-ray generator to measure the intensity, decay time, and emission spectrum of any fluorescent emissions from powdered samples. We will also perform molecular orbital computations to predict the scintillation properties of candidate materials (both doped and undoped compounds), and use these theoretical predictions to guide our search. Finally, many of the candidate compounds (especially doped compounds) are not commercially available, and so we will synthesize a large number of the compounds that we test.