Poznań Radiocarbon Laboratory is equipped with the “Compact Carbon AMS” machine produced by NEC, and the self-designed lines for graphite production from natural samples.
Our AMS machine is characteristic first by a low voltage accelerator, that makes the spectrometer construction simpler, its size smaller and the maintenance easier than in case of the larger AMS 14C systems.
We provide a radiocarbon dating service for people involved in archaeological and environmental research and carry out research into very low level measurements of radiocarbon in biological specimens.
ORAU's dating service operates on a commercial basis and in conjunction with NERC/ARHC which funds the NRCF programme for British archaeologists and English Heritage.
Complementary to our work with radiocarbon we also have interests in the use of stable isotopes to help in the study of past human diet.
Most of the obtained 14C dates formed clear groups, confirming that individual buildings were constructed in separate periods.
Calibrated 14C dates of these phases agree well with the constraints provided by historical sources, and enable us to set their ages with accuracy better than previously available.
In particular, we have learned that the oldest rotunda was built at the boundary of the 10/11th centuries, and the church and the abbot? However, some samples gave much too old 14C ages, clearly reflecting the use of old wood for firing.
These problems were revealed only for samples from the rotunda and for the gypsum stone ornamental details.
Archaeological excavations performed for many years in Łekno, central Poland, have exposed relicts of wooden fortified settlements, and in its enclosure also basements of stone buildings, consisting of Romanesque rotunda and a Cistercian monastery, including an oratory, church, and abbot? Earlier archaeological, structural, and stratigraphical studies have shown that these buildings were constructed in a sequence and represented several phases of development.
In this paper, we present results of radiocarbon dating of stone buildings of the rotunda and the monastery.
For 14C dating, we used tiny pieces of charcoal retrieved from calcareous and gypsum mortar binding stone elements from the buildings.
These pieces were incorporated in mortar during the firing process, where the fuel used for firing was wood.