Retrospective assessment of environmental dose rates using optically stimulated luminescence from Al₂O₃:C and quartz

As part of our continuing work on assessing the usefulness of natural and artificial dosemeters in retrospective accident dosimetry, the natural photon dose rates within bricks have been measured using the optically stimulated luminescence (OSL) from Al2O3:C single crystal dosemeters. These were placed in bricks in house walls for two weeks to integrate the environmental dose rates after which their OSL signals were measured. These results were compared with (1) OSL measurements of quartz samples extracted from the bricks and (2) dose rates determined from laboratory measurements of the natural radionuclide concentrations. It is concluded that the excellent OSL characteristics of Al2O3:C are attractive for use in short-term evaluations of the environmental dose rates. Depth dose profiles were also measured in bricks, after irradiation in the laboratory with Cs-137 gamma rays, using (1).Al2O3:C single crystals distributed in holes across a brick section and (2) quartz (extracted from the matrix of the brick) taken across the same section. These were compared with typical depth dose profiles found in bricks collected in the Chernobyl accident area and demonstrate retrospectively that the average energy of the initial accident radiation was lower than that of Cs-137 gamma rays.