The photostimulated luminescence (PSL) characteristics of an imaging plate (IP) irradiated with α-ray has been experimentally investigated in order to construct a theoretical model on PSL phenomenon. In this way the nonlinearity of PSL intensity to α-ray dose, the dependence of PSL intensity decay on PSL excitation light power and the saturation of PSL intensity with increasing PSL excitation light power have been found.
We propose a rate equation that describes the time evolution of the number of holes and F centers in the phosphor with α-ray dose and show that the nonlinearity of the PSL intensity to α-ray dose is caused by hole and F center recombination losses.
Next we construct a theoretical model for the interaction of the PSL excitation light photon with the F center and the recombination of the conduction band electron with the hole. This shows that the constructed PSL model reproduces the decay of PSL intensity and the relationship between α-ray dose, PSL excitation light power and PSL intensity.
Finally, fading experiments of IP have been performed. With elapsed time there was a rapid decrease of PSL intensity with a corresponding increase in its fluctuation. We propose a theoretical model for the fading of the IP and thereby show that the fading phenomenon is caused by the production of a large and fluctuating number of unstable F (Br-) centers.
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