T04_P23

Safe delivery of graphite targets to AMS facilities, to minimize contamination. The final step of BRAVHO laboratory at Bologna University

Tassoni L¹, Kromer B², Friedrich R³, Wacker L⁴, Friedrich M⁵, Paleček D¹, Pelloni E¹, Talamo S¹

¹University of Bologna, Bologna, Italy, ²Heidelberg University, Heidelberg, Germany, ³Curt-Engelhorn-Centre Archaeometry, Mannheim, Germany, ⁴Laboratory of Ion Beam Physics, ETH, Zurich, Switzerland, ⁵University of Hohenheim, Stuttgart, Germany

Nowadays, most laboratories can reliably remove contamination during the pretreatment of organic samples (e.g. bones, charcoal or trees) thanks to several methods commonly used by the radiocarbon community. However, what about the final step, the storage of graphite? Rarely do the laboratories produce their own graphite and ship them as pressed targets to AMS facilities for measurement. Pressed graphite in aluminium targets is vulnerable to contamination and during the shipment or storage there can be an introduction of exogenous carbon.

Here we report a test on some archaeological samples materials (i.e. charcoal, bones and trees) from different environments and different time periods (from the Modern Age to the Middle Paleolithic period) which were transformed into graphite, with the AGE III (Automated Graphitization Equipment, IonPlusAG, Switzerland), pressed into targets at the BRAVHO lab (Bologna Radiocarbon laboratory devoted to Human Evolution) and sent to two different AMS laboratories to be dated. The two AMS labs chosen for this experiment are the Curt-Engelhorn-Centre Archaeometry, Mannheim, Germany and the Laboratory of Ion Beam Physics, ETH, Zurich, Switzerland. The experiment shows that it is possible to produce graphite in a sample preparation laboratory and send it safely to an AMS laboratory for measurement in a short time without significant contamination. Close cooperation and coordination between our chemical laboratory and AMS facilities, high standards in contamination removal and efficient measurement planning enabled us to obtain reliable outcomes within short times.