Department of Physics and Astronomy

Accelerator mass spectrometry in geology and archaeology

In addition to the stable carbon isotopes 12C and 13C, the atmosphere contains the rare isotope 14C, with a half-life of 5730 years. This isotope is constantly replenished by cosmic radiation. All living beings take up carbon from the atmosphere in their metabolism, and because the carbon is constantly replaced they retain a constant level of 14C. When they die, the 14C decays while the stable isotopes remain constant. By measuring the ratio of remaining 14C to 12C the archaeological samples are dated.

As the ratio is typically in of the order of 10-14 for archaeological samples, highly elaborate sample preparation procedures and precise measurements have to be performed to unambiguously determine the age of the sample. Our laboratory has a long standing expertise in both development and application of these procedures and performs state-of-the-art 14C-dating with several thousands of measurements annually for miscellaneous applications.

Complementary to 14C, other rare-isotope experiments are routinely performed for 10Beryllium and 129Iodine. Similar in concept to 14C-dating, these experiments cover much longer time-spans due to longer half-life of the isotopes of interest. Precision-measurements of the isotopic ratios addresses other applications such as the climate history, the solar cycles and the water circulation on earth – at present and millions of years back in time.

Here is a form for download, for description of samples for 14C dating:

Selected publications

Martin-Puertas , Matthes K , Braue A , Muscheler R, et al.
Regional atmospheric circulation shifts induced by a grand solar minimum, Nature Geoscience 5 (2012) 397 doi:10.1038/ngeo1460

Matthias K, Cristian C, Tschentscher F, Geisert H et al. ,
A view of Neandertal genetic diversity
Nature Genetics 26 (2000) 144 doi:10.1038/79855