K-edge Radiography and applications to Cultural Heritage

The present work of thesis is focused on application of X-ray K-edge technique to paintings. This technique allows one to achieve a topographic map of a pigment on the whole surface of the painting. The digital acquisition of radiographic images by using monochromatic X-ray beams allows to take advantage of the sharp rise of X-ray absorption coefficient of the elements, the K-edge discontinuity. Working at different energies, bracketing the K-edge peak, allows recognition of the target element. The K-edge radiography facility installed at Larix Laboratory, at Department of Physics in Ferrara, consists of a quasi-monochromatic X-ray beam obtained via Bragg diffraction on a mosaic crystal from standard X-ray source. In this work the K-edge technique and the facility used are illustrated. A characterization of the monochromatic beams in the energy range 7-40 KeV range and the elemental mapping on pictorial layers obtained are presented. At the end, a transportable facility for digital radiography is presented and some radiographic analysis of works of art performed are shown

X-Ray Computed Tomography In Situ: An Opportunity for Museums and Restoration Laboratories

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\u2014in a restoration laboratory or in a museum\u2014the 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 \u201cL. Pigorini\u201d 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 \u201cStatue Vestite\u201d (devotional dressed statues) of the Diocesan Museum of Massa

Chemical analysis and computed tomography of metallic inclusions in Roman glass to unveil ancient coloring methods

This paper describes the analysis of two near-spherical metallic inclusions partially incorporated within two Roman raw glass slags in order to elucidate the process that induced their formation and to determine whether their presence was related to ancient glass colouring processes. The theory of metallic scraps or powder being used in Roman times for glass-making and colouring purposes is widely accepted by the archaeological scientific community, although the assumption has been mainly based on oral traditions and documented medieval practices of glass processing. The analysis of the two inclusions, carried out by X-ray computed tomography, electrochemical analyses, and scanning electron microscopy, revealed their material composition, corrosion and internal structure. Results indicate that the two metallic bodies originated when, during the melting phase of glass, metal scraps were added to colour the material: the colloidal metal–glass system reached then a supersaturation condition and the latter ultimately induced metal expulsion and agglomeration. According to the authors’ knowledge, these two inclusions represent the first documented and studied finds directly associated with the ancient practise of adding metallic agents to colour glass, and their analysis provides clear insights into the use of metallic waste in the glass colouring process.This paper describes the analysis of two near-spherical metallic inclusions partially incorporated within two Roman raw glass slags in order to elucidate the process that induced their formation and to determine whether their presence was related to ancient glass colouring processes. The theory of metallic scraps or powder being used in Roman times for glass-making and colouring purposes is widely accepted by the archaeological scientific community, although the assumption has been mainly based on oral traditions and documented medieval practices of glass processing. The analysis of the two inclusions, carried out by X-ray computed tomography, electrochemical analyses, and scanning electron microscopy, revealed their material composition, corrosion and internal structure. Results indicate that the two metallic bodies originated when, during the melting phase of glass, metal scraps were added to colour the material: the colloidal metal-glass system reached then a supersaturation condition and the latter ultimately induced metal expulsion and agglomeration. According to the authors' knowledge, these two inclusions represent the first documented and studied finds directly associated with the ancient practise of adding metallic agents to colour glass, and their analysis provides clear insights into the use of metallic waste in the glass colouring process

X-ray tomography of large wooden artworks: The case study of "Doppio corpo" by Pietro Piffetti

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Tomografia a raggi X per manoscritti

This review presents the studies and the results achieved in the framework of the “Virtual X-ray Reading – VXR” project devoted to X-ray tomography for manuscripts.  The project started in 2014 at École Polytechnique Fédérale de Lausanne (EPFL, Switzerland) and was part of the ambitious “Venice Time Machine” project. VXR aimed to test the feasibility and develop an alternate digitization technique for ancient manuscripts based on X-ray tomography. Research and technology made considerable progress in increasing the speed and the safety of the traditional digitization process of ancient collections, but, despite this, imaging of ancient, fragile, or un-opened documents remains a formidable challenge. Thanks to the high penetration of X-rays, using X-ray tomography, the acquisition of a 3D – tomographic – volume is possible even without opening the document. The X-ray contrast necessary for the readability is linked to the chemical composition of the ancient inks, such as the high X-ray absorption of the iron gall inks mainly used for centuries in Europe. In this review, I present the studies conducted to develop this technology, from the investigations on the ink chemistry to the imaging feasibility tests performed using extensive centralized facilities such as synchrotrons and the imaging of a 200-pages manuscript book the tomography of a 14th Venetian sealed last wills.In questa review verranno presentati gli studi e i risultati ottenuti nell’ambito del progetto “Virtual X-ray Reading” dedicato alla tomografia X.  Il progetto VRX, partito nel 2014 presso l’École Polytechnique Fédérale de Lausanne (EPFL, Svizzera), era parte dell’ambizioso progetto “Venice Time Machine”. Il progetto VXR aveva lo scopo di testar la fattibilità e di sviluppare una tecnica di digitalizzazione di manoscritti alternativa basandosi sulla tomografia a raggi X. La ricerca e la tecnologia hanno fatto notevoli progressi nell’incremento della velocità di digitalizzazione e nella sicurezza dei processi di digitalizzazione di antiche collezioni ma, nonostante ciò, l’acquisizione di documenti antichi, fragili o mai aperti rimane una sfida formidabile. Grazie all’alto potere di penetrazione dei raggi X, con la tomografia è possibile l’acquisizione tridimensionale del volume dell’oggetto senza la necessità di aprire il documento. Il contrasto radiografico necessario per la leggibilità del documento è dato dalla composizione degli inchiostri antichi, come l’alto assorbimento X degli inchiostri ferro-gallici diffusamente utilizzati in Europa per secoli. In questa review presento gli studi condotti per sviluppare questa tecnologia, dalle indagini sulla chimica degli inchiostri, ai test di fattibilità condotti usando grandi facilities come i sincrotroni, dall’acquisizione di un libro manoscritto di 200 pagine, ed alla tomografia di un testamento veneziano del 14th secolo ancora sigillato

Ancient administrative handwritten documents: virtual x-ray reading

A method for detecting ink writings in a specimen comprising stacked pages, allowing a page-by-page reading without turning pages The method compris- es steps of taking a set of projection x-ray images for different positions of the specimen with respect to an x-ray source and a detector from an apparatus for taking projection x-ray images; storing the set of projection x-ray images in a suitable computer system; and processing the set of projection x-ray images to tomographically reconstruct the shape of the specimen

Ricostruzione geofisica del sottosuolo dell'area di Casaglia

Nell’ambito del Progetto Geotermia di Casaglia, l’ENI ha messo a disposizione del Comune di Ferrara alcune linee sismiche migrate. (Fig 3 ,4). Con le sequenze puntuali dei valori di velocità delle onde P è stato costruito un modello 3D del sottosuolo dell’area di Casaglia, di dimensioni 32x7 km (evidenziato nelle immagini sottostanti rettangolo verde, Fig. 1,2,3). Nella Fig. 2 sono riportati gli epicentri degli eventi principali (ML>5,0) avvenuti il 20 maggio 2012 ed il perimetro della rete microsismica di controllo del serbatoio geotermico di Casaglia, di proprietà del Comune di Ferrara (pentagono azzurro) . Il modello 3D si estende !no a 5 km dal p.c. Sia le rappresentazioni cromatiche 3D (Fig. 6) che le sezioni orizzontali (depth slices) de!niscono in maniera chiara e suggestiva la complessa struttura dell’alto ferrarese, ivi compresi i sovrascorrimenti che hanno localmente raddoppiato la sequenza stratigra!ca. Questo modello costituisce un possibile e dettagliato «input» per il calcolo di scenari di scuotimento che coinvolgano anche questa struttura in futuro

Ancient administrative handwritten documents: X-ray analysis and imaging

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.ISSN:0909-0495ISSN:1600-577

X-ray Spectrometry and imaging for ancient handwritten document

We detected handwritten characters in ancient documents from several centuries with different synchrotron x-ray imaging techniques. The results were correlated to those of x-ray fluorescence analysis. In most cases, heavy elements produced high image quality suitable for tomography reconstruction leading to virtual page-by-page “reading”. When absorption is too low, differential phase contrast (DPC) imaging can reveal the characters from the substrate morphology. This paves the way to new strategies for information harvesting during mass digitization programs. This study is part of the Venice Time Machine project, an international research program aiming at transforming the immense venetian archival records into an open access digital information system. The Archivio di Stato in Venice holds about 80 kms of archival records documenting every aspects of a 1000 years of Venetian history. A large part of these records take the form of ancient bounded registers that can only be digitize through cautious manual operations. Each page must be turned manually in order to be photographed. Our project explore new ways to virtually “read” manuscripts, without opening them,. We specifically plan to use x-ray tomography to computer-extract page-by-page information from sets of projection images. The raw data can be obtained without opening or manipulating the manuscripts, reducing the risk of damage and speeding up the process. The present tests demonstrate that the approach is feasible. Furthermore, they show that over a very long period of time the common recipes used in Europe for inks in “normal” handwritings - ship records, notary papers, commercial transactions, demographic accounts, etc. – very often produced a high concentration of heavy or medium-heavy elements such as Fe, Hg and Ca. This opens the way in general to x-ray analysis and imaging. Furthermore, it could lead to a better understanding of the deterioration mechanisms in the search for remedies. The most important among the results that we will present is tomographic reconstruction. We simulated books with stacks of manuscript fragments and obtained from sets of projection images individual views -- that correspond indeed to a virtual page-by-page “reading” without opening the volume