Experimental Investigation of the Effect of Irradiation Intensity on the Production of F Centers in NaCl

The effect of x-ray intensity on the room temperature production of F centers has been studied experimentally. It was found that the initial rate of production (number of F centers produced per incident photon) is independent of intensity. However, the total first-stage coloration that can be produced increases with increasing intensity. Part of the first-stage coloration produced by a high-intensity radiation is bleached upon reducing the intensity. The coloration in the second stage was found to be independent of the intensity. The rate of coloration in the third stage (the relatively rapid coloration following the second stage) was found to increase with increasing intensity. The excess third-stage centers produced by a high-intensity radiation over those that would be produced by an equivalent lower intensity radiation were bleached upon reducing the intensity to the lower value.