Two-dimensional measurement of natural radioactivity of granitic rocks by photostimulated luminescence technique

Two-dimensional measurement of radiation produced by natural irradiation of granitic rocks was performed by the use of an imaging plate, which is a st orage film coated with photostimulated phosphor (BaFBr:Eu-2+). Radiation images of small volume specimens, such as thin sections were obta ined with the imaging plate. Irradiation images of granitic rocks are inhom ogeneous and the intensity of photostimulated luminescence per unit area, w hich is principally converted into the integrated dose, increases with the increasing potassium content in the rocks. The results of the present study indicate that the disintegration of K-40 is the dominant radiation source of granitic rocks. The imaging plate is a new research tool for the evaluat ion of the natural radioactive properties of geological materials and is ap plicable as a semi-quantitative two-dimensional dosimeter for natural radio activity.