Dresden 2009 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 12: Poster II

DF 12.12: Poster

Mittwoch, 25. März 2009, 09:30–12:30, P5

Radioluminescence Investigations on Alumosilicates for Age Determination — •Susanne S. Pfeifer and Matthias R. Krbetschek — Saxon Academy of Sciences, Quaternary Geochronology Section, Inst. of Appl. Physics, TU Freiberg, Leipziger Str. 23, D-09599 Freiberg/Sa., Germany

Age determination of geological and archaeological objects using luminescence phenomena follows the basics of solid state dosimetry of ionising radiation. Luminescence capability is created due to the interaction of radiation with the crystal lattice by charge trapping at defect sites. This metastable state can be built up and last over geological periods and read-out by luminescence stimulation. As the radiation field is created by the decay of natural radioisotopes there is a time dependence of the luminescence signal. Feldspars (alumosilicates) are beside quartz mostly used in luminescence dating of young rocks and artefacts. We carried out radioluminescence investigations on such minerals: i) To determine their potassium concentration (as internal 40K is a main contributor to the radiation field) based on a peak-shift phenomenon in the far-red spectral range (700-750 nm), which allows concentration determination on very small sample amounts. ii) To achieve radioluminescence dating on single mineral grains (200-300 µ m) by spatially resolved measurements so that sample inhomogenities (defect distribution) can be observed more in detail. The latter is based on a newly developed EMCCD camera measurement system. Hence, a wider age range of the IR-radiofluorescence dating method and higher precision of age data for Archaeology and Quaternary Geology will be achieved.