FWF Project No. L430-N19Portable ART Analyser (PART) – Development and construction of an innovative and optimised portable XRF instrument for the in situ, non-destructive study of unique and valuable artworks
Co-workers: Dr. Katharina UHLIR, in cooperation with the Atomic Institute (ATI) – Vienna University of Technology and the International Atomic Energy Agency (IAEA) – Seibersdorf Laboratories X-ray fluorescence (XRF) analysis is one of the most widely used analytical techniques for the scientific study of cultural heritage today. Its biggest advantage is the non-destructiveness of the investigation, providing not only qualitative information on the composition of an object but often also (some) quantitative information. Recent developments enabled the construction of portable XRF systems of various types, some focussed on flexibility, others on easy mobility. Nevertheless, one of the still unsolved problems during the in situ analysis – where low energy radiation is absorbed in air – is the detection of low Z elements. The KHM with its affiliated institutions MVK and ÖTM holds extensive collections of highly valuable objects – often unique in the world. Within this rich variety of outstanding (art) historical objects the materials, forms and sizes, and restrictions for transport are offering a wide range of applications for in situ XRF analysis. Therefore, an XRF instrument capable for the use at the KHM has to be highly flexible, easy to move, and has to possess a broad elemental detection range. Some years ago a prototype portable XRF instrument was constructed at the International Atomic Energy Agency (IAEA), Seibersdorf Laboratories, together with the Atomic Institute (ATI) – Vienna University of Technology. By using a vacuum chamber, designed to house the measuring head, the problem of the detection of low Z elements is to be solved. Through a Kapton™ window the investigated spot can be focussed at about 1-2 mm distance outside of the chamber, therefore minimising absorption losses in the excitation and x-ray fluorescence radiation paths. Test measurements applying this instrument at the KHM showed the need for several improvements, especially concerning the detection limits of low Z-elements (i.e. sodium) for the investigation of glass and enamel, the size and shape of the vacuum chamber, the bending of the vacuum window, the flexibility and positioning of the whole instrument, and the fast evaluation of the in situ analysis. Within this project an improved portable XRF instrument is developed and constructed that meets the high demands of the KHM, based on a co-operation of the Conservation Science Department, the ATI, and the IAEA. This improved instrument will be used for performing some selected case studies on the composition of unique and valuable artworks with an emphasis on the investigation of glass and enamel as well as of pigments and metal alloys. For example, a collection of 16th century glass jewellery from the area of Archduke Ferdinand II, the collection of so called “Rudolfinisches Email”, and about 30 enamelled gold and silver objects of the 15th and 16th centuries will be investigated concerning the glass/enamel composition. In addition, analyses of metal objects – e.g. the collection of Renaissance and Baroque bronzes held in the Collection of Sculpture and Decorative Arts and of ancient Sasanian silver coins – and partly complexly shaped paper objects from the ÖTM will be done in connection with ongoing research projects, scientific studies and conservation work.