Recent developments and new perspectives of Ion Beam Analysis for Cultural Heritage

Novella Grassi, Recent developments and new perspectives of Ion Beam Analysis for Cultural Heritage, Tese de Doutoramento, Università Degli Studi di Firenze, 2005

Since the middle of the Eighties, the main activity of the group of applied nuclear physics in Florence has been the development of analytical techniques based on the use of accelerated particles (Ion Beam Analysis, IBA), and their application for investigating in a non destructive way the composition of materials in different fields. Among these, particular experience has been attained by the group in the field of Cultural Heritage, and in the past twenty years a large variety of works were analysed in collaboration with many Institutions in Europe, and Italy in particular, such as the Laboratoire de Recherche des Musées de France at the Louvre, the Max Planck Institut für Wissenschaftsgeschichte in Berlin, the National Library and the Laurentian Library in Florence, the Vatican Library, and the Opificio delle Pietre Dure. With OPD in particular, a very close and continuous collaboration was established.

Also thanks to a non-negligible contribution of the Florence group to their development, IBA techniques using an external beam set-up are currently regarded as “standard” techniques for analysis in many fields of art and archaeology, and they are extensively and successfully applied also in other laboratories in the world. Besides applications in the standard set-ups, the interest of the Florentine group in the latest years has been directed to develop innovative improvements in the instrumentation and to test the new perspectives arising just from the new instrumentation.

This work reports the most significant results of all my activity during the last three years. In Chapter 1, the main features of Ion Beam Analysis techniques are briefly recalled and the new Florence accelerator laboratory is presented, with particular focus on the perspectives of development a priori offered for applications in the field of Cultural Heritage.

Chapter 2 illustrates how stratigraphy of layered materials can be investigated using proton beams of different energies (with the technique of differential PIXE - Particle Induced X-ray Emission); in particular, merits and limits for the analysis of paintings (a field not often investigated by IBA) are pointed out. We had the opportunity of applying differential PIXE and PIGE (Particle Induced Gamma-ray Emission) on two paintings of great artistic value: the extensive study on the “Madonna dei fusi” by Leonardo da Vinci and preliminary results from “Ritratto Trivulzio” by Antonello da Messina will be described.

In Chapter 3 the analytical quantitative potential of PIGE for determination of light element concentration is thoroughly discussed. For the specific case of Na quantification in glass matrices, results of measurements on glass standards are presented. Measurements on glass tesserae from the excavations of the Roman complex of Villa Adriana (Tivoli) are then described, as an example of the great advantage of combining PIXE and PIGE for obtaining quantitative results. The perspective of performing PIGE at higher beam energies with respect to the standard 3 MeV value is discussed in the final paragraph, where the first measurements carried out at higher energies with the new Tandetron accelerator are also reported.

Finally, Chapter 4 introduces a new procedure for Ion Beam Analysis in the archaeometric field, which enables elemental imaging; compositional maps are obtained by scanning the object under analysis with a beam size of the order of hundred microns. The usefulness of such a way of performing IBA (rather than “point” analysis) for obtaining more reliable and unambiguous results is verified by tests on ancient inks, Roman glass and metal point drawings.

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