Ion beam analysis of art works: 14 years of use in the Louvre

Abstract

For more than 14 years, an IBA facility has been operated in the Louvre for the study of works of art and archaeology. The choice of this equipment derives from the non-destructive character of IBA techniques which has been further strengthened by designing an external beam line permitting the in-air analysis of large or fragile works of art without sampling. Successive improvements have markedly extended the analytical capability of the set-up. The measurements were originally restricted to PIXE–PIGE combination using an external millimetre-sized-beam. By adding a focusing system and an ultra-thin exit window we were able to obtain external beams of protons and alpha particles of respectively 10 and 50 μm in diameter, with low energy straggling. These features have permitted to apply in external beam mode other IBA techniques including RBS, NRA and more recently ERDA. Moreover, elemental maps can be drawn in PIXE and PIGE modes by mechanically scanning the sample under the fixed beam within a lateral range much larger than conventional nuclear microprobes. This facility is used for both short investigations at the request of museum curators and extensive research works in art history and archaeology. Several examples are given to highlight the impact of this tool on cultural heritage.