National Nuclear Physics Institute (INFN) and University of Firenze

Via Sansone, 1 - 50019 Sesto Fiorentino, Firenze - Italy

Tel. +39 055457 2707/2640 - Fax: +39 055457 2641

E-mail address: mando@fi.infn.it

Ion Beam Analysis (IBA) and radiocarbon dating are probably the best known and most extensively used nuclear techniques for diagnostics in the field of Cultural Heritage.

As to IBA techniques, they are a very powerful tool to measure the composition of any material in a fully non destructive way. On the other hand, knowing e.g. which kind of pigments were used for a painting, or which metal alloy in a coin, in a jewel or in a statue, or measuring the composition of the inks used in a manuscript, and so on, can provide a huge amount of precious information to the humanists. For example, it can give them hints about the period of production of the work (or even about authenticity or not of the work), or concerning the availability or not of certain raw materials in the place of production, or finally on the technological skills already developed in ancient times. This kind of information can be easily obtained using a beam of particles produced by an accelerator to “bombard” the material under investigation (i.e., the pigment, or metal, or ink, etc.) and detecting the energies of the induced X rays, gamma rays, secondary or backscattered primary particles, which are characteristic of the atomic elements present in the “target”. The physics of the beam-target interactions leading to the emission of the characteristic radiation is such that these analyses can be performed without procuring any damage to the investigated material, and this is a basic requirement when dealing with precious objects such as the works of art!

As far as radiocarbon (i.e. ¹⁴C) dating is concerned, this technique is very well known even to the general public. In the past two decades or so, a huge development of the analytical capabilities has been achieved in this field, thanks to the use of Accelerator Mass Spectrometry (AMS) to measure the ¹⁴C concentration in the material to be dated. With AMS, dating of finds as old as 50000 years is possible, “sacrificing” only tiny quantities of the sample (order of the milligram). This datable time lapse covers all the historical and pre-historical period of relevance to the human kind, so that ¹⁴C dating (together with thermo-luminescence dating) is a basic tool for the archaeologists.

n Florence, our group has been performing IBA for the Cultural Heritage for over twenty years now, working until two years ago with a single-ended Van de Graaff accelerator, re-used for this purpose after a previous period of use in basic nuclear physics problems. A lot of relevant results were obtained in problems concerning the Cultural Heritage.

Since 2004, a new Tandem accelerator has been installed by INFN in a new laboratory, dedicated just to applications to the Cultural Heritage (LABEC = LAboratorio di tecniche nucleari per i BEni Culturali). With a Tandem, AMS is now also possible; in addition, thanks to the characteristics of the new accelerator the potential of IBA is greatly increased. Our laboratory is thus currently operating with both IBA and AMS techniques; switching from one to the other is a matter of hours or even less, if needed, so that the use of our facility is very flexible.

Examples of both IBA applications and ¹⁴C dating with AMS will be given.