Non-destructive measurements on roman pottery

The portable BSC-XRF spectrometer (Beam Stability Controlled-XRF) and the portable PIXE-alpha system, realised at the LNS/INFN laboratories of Catania in collaboration with the Italian CNR, have been used for the non destructive analysis of some Roman pottery artefacts of different typologies. The XRF techniques has been used for the quantitative determination of some trace elements (Rb, Sr, Y, Zr and Nb) of interest in provenance studies. Analysis has been performed by using a multi-linear regression approach developed at the LNS/INFN laboratories. It could be observed that the XRF analysis is limited to the near surface layer (about 200 um) and a quantitative determination is meaningful only when the material being analysed is homogenous. In order to test the homogeneity of the material composing the analysed samples, a small portion (about 1 gr) of the artefacts has been powdered. The powdered pellets have been measured and quantitatively analysed. A comparison between the non destructive and the destructive data is presented and discussed. Finally, the trace elements composition has been used to classify the artefacts in typological classes by performing a multivariate cluster analysis. The PIXE-alpha method has been used to quantitatively characterise the artefacts glazes; the PIXE investigation is in fact limited to the thin surface layer (less than 10 um) and any contribution from the ceramic body is not present in the PIXE experimental data. .