PIXE in the study of archaeological and historical glass

The particle induced x-ray emission (PIXE) method, especially when carried out with an external beam, is a remarkable tool for the scientific investigation of objects of cultural heritage. We present here two case studies addressing important issues of archaeological and historical glass: deformulation of ancient glass recipes, determination. of provenance of raw materials and understanding the weathering processes endangering these precious artifacts. This contribution illustrates the place of the PIXE technique among other analytical methods based on radiations in the study of this specific material. In the first example, PIXE is used to determine the provenance of a natural glass, obsidian, which forms the support of two paintings of the Spanish master Murillo (17th century.) on display in the Louvre museum. The comparison of the chemical fingerprints obtained by PIXE with an obsidian composition database established by instrumental neutron activation (INAA) and XRF shows that the rectangular obsidian panels were imported from Mexico. These investigations also permit to highlight the complementarities of these analytical techniques. In the second example, PIXE is applied to a 12th-century stained glass window from the Saint-Denis basilica (Paris) to determine the various medieval glasses (soda and potash types) employed in this panel. In addition, by combining p-PIXE with He-PIXE, PIGE (proton-induced gamma-ray emission), p-RBS (Rutherford Backscattering Spectrometry) and He-RBS, alteration markers of the glass surface, useful in conservation science, are evidenced. Copyright (C) 2008 John Wiley & Sons, Ltd.