PART II (Portable ART analyzer) - development of a XRF spectrometer adapted for the study of artworks in the Kunsthistorisches Museum, Vienna

A portable focused-beam X-ray fluorescence (XRF) spectrometer was designed and manufactured taking into account a huge variation in material, size and shape of museum objects. The spectrometer is equipped with a vacuum chamber enclosed with a Kapton-window allowing the detection of chemical elements from Na upwards, which enables the characterization of glass and enamel objects. Two low-power X-ray tubes, one with a Mo-anode the other with a Cr-anode, operating from 4 to 50 kV and 0 to 2.5 mA with a maximum power of 50W and a point focus of about 180 mu m can be used as excitation source alternatively. A polycapillary lens with a spot size of 150 mu m is used for focusing the primary beam to access small details of the different objects, e.g. fine brush strokes in paintings. The vacuum chamber can be evacuated to about 1 mbar. A miniature camera is installed inside the chamber for inspecting the analyzed area through the Kapton-window. Two laser pointers mounted inside the chamber coincide with the focal point of the polycapillary at the investigated spot. The excitation and X-ray fluorescence radiation paths in air are about 1 mm each, minimizing the absorption losses. The spectrometer was designed to maximize the accessibility to all parts of the investigated objects through the use of translation stages and an innovative design of the detection head, especially the vacuum chamber. This article shows the capability of the spectrometer to reach measuring positions in concave parts of objects and presents the determined detection limits of elements. Copyright (C) 2009 John Wiley & Sons, Ltd.