|Conference:||10th International Conference on Particle Induced X-Ray Emission and its Analytical Applications|
|Title:||Differential PIXE measurements for the stratigraphic analysis of the painting “Madonna dei fusi” by Leonardo da Vinci|
|Author(s):||Novella Grassi, A. Migliori, Pier Andrea Mandó, H. Calvo del Castillo|
|Contact :||Novella Grassi|
|Address:||Department of Physics and INFN Florence
I-50019 Sesto Fiorentino (Firenze)
Wood and canvas paintings are characterised by a layered structure, which consists of a preparation substrate (typically composed of gypsum or lead white), one or more pigment layers and, on top of these, the protective varnish (generally organic). With a single PIXE measurement in typical conditions, the proton beam can sometimes reach different layers - depending on their thickness - and the various contributions are thus overlapped in the spectra.
In such cases, a solution to discriminate the depth sequence of elements within the analysed sample is using differential PIXE. The information obtained by spectra analysis is, in general, at a semi-quantitative level because several factors make a detailed interpretation of the data difficult: for example, the number of layers and their thickness is a priori unknown and the same atomic element can be present in more layers, with different abundance.
Differential PIXE measurements have been performed at the KN3000 Van de Graaff accelerator of INFN in Florence on the wood painting “Madonna dei fusi” (ex-Redford version, 1501) by Leonardo da Vinci, in the framework of an extensive project aimed at discovering the “secrets” of painting and drawing techniques of the artist. The analysis allowed us to characterise the pigments and the preparation composition and to give an estimate of the paint layer thickness, which comes out to be particularly thin.