POTENTIAL OF AUTORADIOGRAPHY TO DETECT SPATIALLY RESOLVED RADIATION PATTERNS IN THE CONTEXT OF TRAPPED CHARGE DATING

Abstract

Abstract: Recent developments in optically stimulated luminescence (OSL) dating allow the deter-mination of signals in increasingly smaller sample amounts. This has led to microdosimetry having a larger impact on equivalent dose (DE) distributions and therefore, detection and assessment of spatial distribution of radionuclides has become more important. This study demonstrates the application of autoradiography using imaging plates to determine spatially resolved radiation inhomogeneities in different types of samples. Qualitative evaluations of radiation inhomogeneity are carried out on un-consolidated sediments as well as on hard rock samples. While indicating some limitations of appli-cability, the results demonstrate that the method is an efficient tool to detect and document spatial variations in a sample’s radiation field. It therefore provides a possibility to rapidly screen samples to check whether microdosimetry might affect the DE data. Furthermore, an approach to calibrate autoradiographic images for quantitative use is suggested. Us-ing pressed powder pellets of reference materials, a series of calibration images were exposed, from which a functional relation between specific sample activity and greyscale value in the autoradio-graphic image has been deduced. Testing the calibration on a set of 16 geological samples, of which their radionuclide content is known, shows a good correlation between specific activities calculate