Review of accelerator gadgets for art and archaeology

For 30 years analytical methods based on ion beams have been progressively adapted to art and archaeological issues. By allowing the analysis of artefacts in a non-invasive and non-destructive way, the external beam represents the cornerstone of this evolution. In order to reach in air specifications usually obtained under vacuum, improvements in various directions have been necessary. A large panel of gadgets and experimental arrangements have been designed such as a multi-detector set-up operating in helium atmosphere to extend the range of measured elements, a nuclear microprobe at atmospheric pressure for the study of microscopic details or a reliable beam monitoring system. In addition, specific procedures have been developed to characterise multi-layered samples (easel paintings, alteration layers) by varying either the beam energy or the impinging angle. To improve the sensitivity to trace elements in high-Z materials like metals or for analysing targets too sensitive to stand direct exposure to charged particles, a specific X-ray fluorescence set-up (PIXE-XRF) based on the production of quasi-monochromatic X-rays has been developed. Eventually, the ion beam methods usually restricted for external beams to those based on photon detection (PIXE, PIG.) have been recently extended to methods based on charged particle detection (RBS, NRA and even ERDA), opening new perspectives for determination of light elements and depth profiling. This paper makes an historical review of the adaptation of IBA methods to the study of cultural heritage. (C) 2004 Elsevier B.V. All rights reserved.