Rare earth oxysulphide fluorescent substance used in radiation detectors

摘要

Fluorescent substance for a radiation detector is based on a rare earth oxysulphide of formula (M1-xLnx)O2S in which M is at least one of Y, La and Gd, Ln is at least one of Eu, Pr, Tb, Yb, Dy, Sm and Ho, (2 x 10<-1>) is greater than or equal to x is greater than or equal to (1 x 10<-6>). The substance is doped with at least one element D selected from Zr, Ti, Hf, Se and Te at 10<-4>-10<-6> mol.% to reduce afterglow. Also claimed is a process to produce a fluorescent ceramic with reduced post fluorescence comprising: (a) preparing and homogenising of a pigment powder of the above substance; and (b) compaction of the pigment powder under pressure at temps. above 1200 deg C in an inert or reducing atmos. Further claimed is the use of Zr, Ti, Hf, Se or Te at a concentration of 10<-1>-10<-6> mol.% as an additive to a rare earth oxysulphide fluorescent ceramic to reduce afterglow.