X-ray Computed Tomography (X-ray CT) is a sophisticated non-destructive imaging technique to investigate structures and materials of complex objects, and its application can answer many conservation and restoration questions. However, for Cultural Heritage investigations, medical CT scanners are not optimized for many case-studies: These instruments are designed for the human body, are not flexible and are difficult to use in situ. To overcome these limitations and to safely investigate works of art on site—in a restoration laboratory or in a museum—the X-ray Tomography Laboratory of the University of Bologna designed several CT systems. Here we present two of these facilities and the results of important measurement campaigns performed in situ. The first instrument, light and flexible, is designed to investigate medium-size objects with a resolution of a few tens of microns and was used for the CT analysis of several Japanese theater masks belonging to the collection of the “L. Pigorini” Museum (Rome). The second is designed to analyze larger objects, up to 200 cm and was used to investigate the collection of the so-called “Statue Vestite” (devotional dressed statues) of the Diocesan Museum of Massa.

Introduction: X-ray computed tomography (CT) is now used in the cultural heritage field because it is non-invasive and it can give a large amount of information on the inner structure of the object under study. Until recently mainly medical CT scanners or micro-CT setups have been used, limiting the analysis to relatively small artworks or requiring multiple acquisition and difficult image-joining for objects larger than detector dimensions. Results: To overcome the limitations of ordinary CT devices, a facility for the X-ray tomography of large size artefacts has recently been designed and installed in a protected area of the Fondazione Centro Conservazione e Restauro "La Venaria Reale", a Centre for Preservation and Restoration. This facility, based on a X-ray source, a linear X-ray detector and a high precision mechanical system, has been and will be used to gather information on materials, manufacturing techniques and conservative conditions of artworks undergoing the restoration process. In this paper the results of the tomography of the first analyzed large artistic object are presented, giving an idea of the wealth of information obtained from the CT scan. The presented artwork is the writing cabinet called "doppio corpo", a masterpiece of furniture more than 3 m high, inlaid for Savoy Residences by Pietro Piffetti, the most famous cabinet-maker in Piedmont in the XVIII century. The artwork is now housed in the Quirinale Palace, the official residence of the Italian President in Rome. Conclusions: The CT analysis permitted us to obtain valuable information about the conservative conditions, the presence of previous interventions, the distribution of various materials and the dimensions and arrangement of several wooden pieces, thus allowing for interesting hypotheses about the building technique of this masterpiece.

Detectors are a key feature of the contemporary scientific approach to cultural heritage (CH), both for diagnostics and conservation. INFN-CHNet is the network of the Italian National Institute of Nuclear Physics that develops and applies new instrumentation for the study of CH. This process results in both optimized traditional state-of-the-art and highly innovative detection setups for spectrometric techniques. Examples of the former are X-rays, gamma-rays, visible-light and particles spectrometers tailored for CH applications, with optimized performances, reliability, weight, transportability, cost, absorbed power, and complementarity with other techniques. Regarding the latter, examples are ARDESIA, the array of detectors at the DAΦNE-Light facility, the MAXRS detection setup at the Riken-RAL muon beamline and the imaging facilities at the LENA Laboratory. Paths for next-generation instruments have been suggested, as in the case of the X-ray Superconductive Detectors and X-ray Microcalorimeter Spectrometers, allowing astonishing improvement in energy resolution. Many issues in CH can now be addressed thanks to scientific techniques exploiting the existing detectors, while many others are still to be addressed and require the development of new approaches and detectors.

Handwritten characters in administrative antique documents from three centuries have been detected using different synchrotron X-ray imaging techniques. Heavy elements in ancient inks, present even for everyday administrative manuscripts as shown by X-ray fluorescence spectra, produce attenuation contrast. In most cases the image quality is good enough for tomography reconstruction in view of future applications to virtual page-by-page `reading'. When attenuation is too low, differential phase contrast imaging can reveal the characters from refractive index effects. The results are potentially important for new information harvesting strategies, for example from the huge Archivio di Stato collection, objective of the Venice Time Machine project.