SEARCH FOR ULTRA-FAST, HEAVY-ATOM SCINTILLATORS

本研究的目的是发现新的闪烁体

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.