STUDY OF AFTERGLOW IN X-RAY PHOSPHORS FOR USE ON FAST-FRAMING CHARGE-COUPLED-DEVICE DETECTORS

There is a need in the x-ray imaging community for phosphors with shor t persistence (l/l(o) < 0.1 to 0.01% in less than 0.5 ms). Persistence limits a detector's performance by defining the minimum xray exposure discernible for a given time after a previous exposure, by ghosting o f previous images, and by limiting the dynamic range. We characterize the persistence and relative light output of 25 commercially available and specially synthesized phosphors, five of which are gadolinium oxy sulfide (Gd2O2S) with five different activators, The phosphor's ''prac tical efficiency'' is presented for use with either front-or rear-illu minated CCDs. The persistence of these phosphors is characterized as a function of x-ray intensity, exposure time, and, when possible, impur ity concentrations. Each phosphor's usefulness for particular x-ray im aging experiments is also discussed. (C) 1997 Society of Photo-Optical Instrumentation Engineers.