Energy-dispersive X-ray fluorescence and diffraction portable system for cultural heritage applications

A portable X-ray diffraction (XRD) and X-ray fluorescence (XRF) system, based on energy dispersive detection in reflection geometry, has been developed for the non-invasive study of cultural heritage materials. This analytical system is an open-work platform based on a low-power miniaturized X-ray tube (Ag anode), a single Si-drift detector, and a set of collimators that have been mounted on a compact and versatile manual or motorized stage, which allows independent and precise angular positioning of both source and detector and the study of complex geometry objects. The design of two instruments and experimental setups, and their advantages are discussed. The XRF and XRD analytical performance has been tested through the analysis of standard reference materials and some applications, including provenance study of obsidian and 'green stone' artifacts, identification of pigments in a model of fresco painting, and chemical element analysis of bones. The main advantages of portable energy dispersive X-ray diffraction systems compared with commonly used angle dispersive X-ray diffraction (ADXRD) instruments are shorter measurement times and compactness. Moreover, optimum XRF spectra can be collected because a polychromatic beam is used instead of a (quasi) monochromatic beam as in an angle dispersive X-ray diffraction-X-ray fluorescence portable system. Results demonstrate that it is possible to identify the main crystalline phases in a measurement time of 100s-600s and the system is sensible enough for answering common questions, as the ones presented, in the cultural heritage field.