There is a need in the x-ray imaging community for phosphors with short persistence (I /Ib<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 of 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 oxysulfide (Gd2O2S) with five different activators. The phosphor’s ‘‘practical efficiency’’ is presented for use with either front- or rearilluminated CCDs. The persistence of these phosphors is characterized as a function of x-ray intensity, exposure time, and, when possible, impurity concentrations. Each phosphor’s usefulness for particular x-ray imaging experiments is also discussed.
|