Development of a functional equation to correct fading in imaging plates

The time evolution of PSL in certain photo stimulable phosphors has been studied for several storage temperatures ranging from 0°C to 60°C and for time periods from 0.03 to approximately 500 h after irradiation. The experiments were carried out using commercially available BaFBr:Eu²⁺ phosphors: BAS-UR and BAS-TR (Fuji Film Co.). The fading curves obtained after irradiation with a ²⁴⁴Cm source were analyzed by applying Arrhenius’ equation to the experimental results, the same method reported previously (Ohuchi et al., 2000a). An improved equation, which is a function of elapsed time (t) and absolute temperature (K), was proposed. Comparison of the data of the experiment and calculated results based on a model consisting of four components for BAS-UR and five components for BAS-TR showed excellent agreement at all temperatures and over all time periods. The formula was also confirmed as giving the proper calculated photo-stimulated luminescence (PSL) corresponding to the temperature changes between the elapsed times, and showed good consistency with the experimental results.