STOICHIOMETRIC CERIUM COMPOUNDS AS SCINTILLATORS .2. CEP5O14

Results concerning the relative importance of several processes which are responsible for the efficiency and speed of a scintillator are presented here. Arguments for concentrated (stoichiometric) materials are presented and illustrated in the case of Ce-pentaphosphate, (CeP5O14). The low density of this material does not make it a viable scintillator, but its remarkable simplicity and relatively easy technology make it perfect to study basic physical mechanisms of scintillation in concentrated materials. Based on studies of a series of CexLa1-xP5O14 crystals, we formulate general conclusions concerning the relative importance of the process starting with direct ionization of the emitting centers (Ce3+) versus long range gathering of electron-hole pairs. These conclusions provide guidance form optimizing speed and efficiency of future concentrated scintillators. In addition some peculiarities of the Ce-pentaphosphate luminescence are reported and interpreted.