SCINTILLATION MECHANISMS IN RARE-EARTH ORTHOPHOSPHATES

Although conversion efficiency of orthophosphate materials is limited by the high frequency vibrations of the PO4 group, some of them show r emarkably promising scintillation properties. In order to understand t hat behavior, we have studied the orthophosphates of Lu and Yb in vari ous combinations both with and without Ce as an activator. We conclude that, although both Ce and Yb ions scintillate, they also show strong tendency toward mutual quenching. The mechanisms and consequences of this quenching are discussed.