RADIOCARBON DATING BY ACCELERATOR MASS SPECTROMETRY IN ITALY

• L. Calcagnile, G. Quarta, M. D'Elia (Department of Engineering of Innovation, University of Lecce, via per Monteroni, 73100 Lecce, Italy)

A new facility for accelerator mass spectrometry radiocarbon dating and for ion beam analysis has been put in operation at the University of Lecce in Lecce, Italy. The facility has been founded in order to be a national centre for the development and the application of nuclear spectroscopy techniques in the studies on cultural heritage.

The facility is based on a 3 MV Tandetron^TM accelerator manufactured by High Voltage Engineering Europa (The Netherlands) and is equipped with three experimental lines for accelerator mass spectrometry, ion beam analysis and high-energy ion implantation.

We present the general layout of the facility reporting the main characteristics of the experimental apparatus and the results of the radiocarbon measurements performed in the first year of operation. These measurements have shown that with the new system the ¹⁴C/¹²C and the ¹³C/¹²C ratios can be measured with a precision of 0.3 % and of 0.04 % respectively. In the facility more than 2500 unknown samples can be measured per year since in the carousel of the accelerator ion source 59 samples can be contemporary placed and automatically measured.

The facility is located in a dedicated building which also accommodates the sample preparation laboratories. They include all the equipment needed for the chemical and physical treatments of organic and inorganic samples: during the first year many different kind of samples have been prepared like human and animal bones, charcoal and wood. The protocols and the equipment we have developed for the preparation of the different kind of samples will be illustrated. The performance tests of this equipment have been carried out by preparing standard IAEA (International Atomic Energy Agency) samples and have shown that the sample preparation background is better than 50'000 years and that no memory effects are induced by the preparation lines.

During the first year, in the frame of a collaboration with the Department of Cultural Heritage of the University of Lecce, more than 200 archaeological samples have been dated. We will show how the radiocarbon measurements have given a fundamental contribution to the solution of many archaeological problems in the field of prehistory, classical and middle age archaeology.

The results of our current research projects, which are planned to expand the analysis capabilities of the facility will be also discussed. They have as main aims the development of an external ion beam line and the design of an innovative analysis system in which optical and nuclear techniques will be integrated in the same experimental apparatus.