1. a Institute of Prehistoric Archaeology, University of Aarhus , Moesgård, DK-8270 , Højbjerg , Denmark
2. b The C-14 Dating Laboratory, The National Museum , Ny Vestergade 11, DK-1471 , Copenhagen K , Denmark
3. c Department of Physics , University of Odense , Campusvej 55, DK-5230 , Odense M , Denmark