A repositioning technique for counting induced fission tracks in muscovite external detectors in single-grain dating of minerals with low and inhomogeneous uranium concentrations

in fission-track dating with the external detector method, an exact match between the grain area scanned for fossil tracks and the area of the external detector scanned for induced tracks is often difficult to achieve. In the simple repositioning-technique proposed here, the muscovite external detector is repositioned track-side down on the grain mount after etching the induced tracks. The fossil tracks are counted by focussing on the grain surface through the external detector. The positioning precision allows track to track matching, and is useful for methodical research and dating of low-uranium and sediment samples, containing a mixture of high- and low-uranium grains. (C) 2003 Elsevier Science Ltd. All rights reserved.