SEARCH FOR ULTRA FAST, HEAVY ATOM SCINTILLATORS

描述（改编自申请人摘要）：主要目的

DESCRIPTION (Adapted from Applicant's Abstract): The primary objective of this research is the discovery of new scintillators with very rapid emissions, and high atomic number, density, and luminosity. A scintillator with higher atomic number and luminosity than Lu2SiO5:Ce, and a decay time <1ns would improve the detection efficiency, spatial resolution, and scatter rejection of positron tomographs, and improve the accuracy of the reconstructed images by providing time-of-flight information. Additional objectives include the discovery of scintillators having higher stopping power and less dead time than Nal(TI) for single photon tomography, and having low afterglow and high light output at longer wavelengths (where silicon photodetectors have their highest efficiency) for x-ray computed tomography. During the course of this project, they have discovered the scintillators CeF3 and PbWO4 (which are in large scale production for high energy physics), and BaCI2, LuAIO3:Ce, LuBO3:Ce, whose crystal growth is under investigation. To accomplish these objectives, they will continue to use empirical and computational guidance in the selection of stoichiometric and doped compounds to synthesize and measure. They have built a pulsed x-ray source specifically designed to measure scintillation from powders as well as from crystal samples with high sensitivity and a timing resolution <120 ps. They will use available molecular orbital computer codes to investigate processes that enable or prohibit scintillation (hole transport, exciton formation, excitation of activator atoms, thermal quenching, etc.) and to develop computational methods for the efficient selection of compounds for synthesis and testing.