A new instrument for X-ray radiography and tomography of large artworks

X-ray imaging is now widely used in the Cultural Heritage field thanks to its non-invasivity and for the high number of information which can be obtained on the inner structure of an object. In the frame of the neu_ART project, aiming to develop state of the art transmission imaging and computed tomography, a facility for X-ray radiography and tomography of large size artefacts has been installed in a dedicated area of the Centro Conservazione e Restauro "La Venaria Reale". This instrument is based on a X-ray source (up to 200 kV), a linear X-ray detector (50 cm long) and a high precision mechanics (both for the movement of the source and the detector, and for the revolution of the object). This device is becoming a routine-tool before the restoration process for 2D (radiography) and 3D (tomography) imaging. In fact one can obtain a great number of information on materials, constructive technique and state of conservation of an artwork in an absolutely non-invasive way. This custom instrumentation allows to obtain radiographies of painted canvas and panels up to 3 m × 4 m in a short time, optimizing the parameters (X-ray energy, current, distances, etc) in real time. It has also been designed and built to overcome the limits connected to CT medical devices, permitting the analysis of only some particular artworks with small size (to fit the acceptance of medical CT scanners) and materials (similar to human tissue). Moreover, it is also more flexible than industrial CT instruments because of its wide flexibility in the geometry (distances among source, object and detectors can be changed up to 4 meters). In this contribution the characterisation of this instrument will be presented, focusing in particular on the achievable spatial resolution and the dynamic range. Furthermore, results obtained with this instrument on very different kinds of artworks will be presented, ranging from the radiographies of large paintings to tomographies of big piece of furniture, statues, columns and other artistic and archaeological objects coming from important Museums and collections.