Retrospective radiation dose reconstruction using optically stimulated luminescence on natural materials

Optically stimulated luminescence (OSL) techniques especially aimed at using natural materials for retrospective reconstruction of accidental radiation doses in populated areas were developed and studied at Risoe as part of an EU research project. Quartz and feldspars separated from building materials, such as bricks and tiles, in addition to porcelain from toilet tanks had their OSL signals measured using different light sources for stimulation to assess radiation doses received by the material. Radiation doses were also evaluated from OSL measured directly on unseparated samples i.e. directly from the surface of brick and tile materials. The lower detection level for e.g. quartz extracted from a modem brick measured using a green light wavelength band as the stimulation light source was found to be less than 1 mGy. The techniques developed and applied are described and results from measurements carried out on a variety of materials are presented. (author)