Inorganic scintillators for the detection of ionizing radiation
The lecture starts with an overview of the operation principle of inorganic scintillators. This part comprises; 1) the interaction phase where ionizing particles produce a large number of free charge carriers in the scintillation crystal. 2) The transport phase where charge carriers are transported to luminescence centers. 3) The luminescence phase leading to emission of the scintillation flash. Here the properties of important luminescence ions like the lanthanides Ce3+, Pr3+, Eu2+, and the s2-elements Tl+, Pb2+, Bi3+ will be discussed. In the next part, the physical and technological aspects that determine the scintillation light yield, scintillation speed, and how that all affects energy resolution and timing resolution of scintillation detection systems are addressed. What are the fundamental limits and have those been reached by modern day scintillators? The theory and models on scintillators will be illustrated by presenting and discussing the properties of well known and widely applied scintillators like e.g. NaI:Tl, CsI:Tl, Lu2SiO5:Ce, BaF2, PbWO4, LaCl3:Ce, LaBr3:Ce. The ideal scintillator does not exist. Some scintillators excel in energy resolution and others in detection efficiency or scintillation speed. One therefore should always find an optimal compromise between detector demands, available scintillators, and price. The final part of the lecture is on the application of scintillators and its requirements.
Curriculum Vitae Prof. Pieter Dorenbos
After his PhD on ionic conductivity in alkaline earth fluorides at the University of Groningen in The Netherlands, he started in 1988 as assistant professor at the Technical University of Delft to develop new scintillator materials for the detection of ionizing radiation. That research topic evolved into a wider field of luminescence materials research. In 2008 Pieter Dorenbos was appointed full professor in Luminescence Materials at the Technical University of Delft where he is now heading the Luminescence Materials Research program. He (co-) authored about 270 peer reviewed journal papers and is inventor of eight patented scintillators. Most important discovery relates to LaBr3:Ce3+, a scintillator that combines record low energy resolution with very fast scintillation response time. His main interests are; 1) scintillation mechanisms and related charge carrier migration and trapping phenomena in the solid state, and 2) the chemistry and physics associated with lanthanide impurity luminescence in inorganic compounds. Dorenbos has developed models that successfully predict the position of the ground and excited states of lanthanide ions in inorganic compounds. The expertise and laboratory infrastructure is directed towards developing new scintillators for radiation detection, new phosphors for lighting, display or solar conversion applications, new charge carrier storage materials for dosimetry and persistent luminescence, improving models for dating sediments, and studying phase switching processes in pure lanthanide compounds.