Scienze di Base e Applicate per l'Ingegneria

The fluorescence spectra from rat bones of different age groups (8, 56 and 78 weeks) and lumber vertebra were measured with 8, 10 and 12 keV synchrotron X-rays. We have utilized the new hard X-ray microspectroscopy beamline facility, X27A, available at NSLS with a primary beam spot size of the order of $10 lm. With this spatial resolution and high flux throughput, X-ray fluorescent intensities for Ca and other trace elements were measured using a liquid-nitrogen-cooled 13-element energy-dispersive high-purity germanium detector. Regarding the lumber vertebra, we acquired the fluorescence spectra from the left, right and middle portions and calcium accumulation was evaluated and compared with the other samples. We have identified the major trace elements of Ca, Ni, Fe and Zn and minor trace elements of Ti, Cr and Mn in the sample. The percentage of scattered radiation and trace element contributions from these samples were highlighted at different energies.

The usefulness of forward geometry in Energy Dispersive X-Ray Fluorescence (EDXRF) analysis has been investigated both experimentally and theoretically. This work relates to milli-and micro-beams, which limits this work to tightly collimated incident X-ray beams (<1 mm). The use of forward geometry also limits the targets to be of thin and intermediate thickness. The advantages and the peculiarities of using a forward geometry for XRF are discussed. Forward X-Ray Fluorescence (FXRF) has features including: (a) high geometrical eciencies when using tightly collimated primary beams; (b) a minimisation in the uncertainty in the interaction volume; (c) a sample thickness at which the production of characteristic X rays is maximised; and (d) a ®ltering action by intermediate thickness samples resulting in an enhancement of the sensitivity for higher atomic number elements with respect to lower atomic number elements. For thin and intermediate thickness samples simultaneous forward and backward geometry XRF can be used to correct for self-absorption eect. Ó

It has become a common practice to include diagnostics and archaeometric studies during a masterpiece restoration. The advantages and limits of this approach are now topic of discussion in the community of researchers that is growing up quickly. The bronze burial monument of Pope Sixtus IV (1471-84) by Antonio del Pollaiolo, now in the Treasure Museum in the Vatican was intended to be located at the center of a chapel, this explains its apparent asymmetry: lack of height and large base. The restoration of the burial monument started in May 2007, it was carried out by first fulfilling a series of non-invasive analyses using a transportable EDXRF to map the composition of the alloy and evaluate the diagnostic capabilities for deterioration processes of the bronze surface. As a consequence of the first non-invasive diagnostic campaign, a second campaign of micro invasive tests was planned and carried out. The samples were analysed with SEM-EDS and XRF techniques. In this article some of the results of the EDXRF tests will be shown together with the procedures set up to maximize the diagnostic information obtained and minimize the need of microsampling from the artefact. The results and the statistical analysis of data show that a straightforward planning of the measurements can give several, sometimes unexpected, results in the definition of the state of conservation of the monument and also from an archaeometric point of view. With a high amount of data, the use of statistical analysis is necessary, for example in our case, the analysis of the variance confirmed the hypothesis of the use of different alloys for the elements of the panels.

Lo scopo di questa ricerca è stato quello di valutare varie metodologie d'indagine non distruttive o micro-distruttive (microscopia ottica, XRF, XRD, SEM-EDS, FTIR-ATR) per analizzare la natura delle patine di corrosione formatesi in ambiente ipogeo sulla superficie di monete di epoca romana in lega a base di rame rinvenute nel sito archeologico di Pompei e per studiare l'avanzamento del fenomeno corrosivo. Le patine sono il risultato dell'interazione tra il manufatto e l'ambiente in cui esso è rimasto sepolto per lungo tempo e sono costituite prevalentemente da composti del rame, a volte mescolati a quelli degli altri alliganti, ad esempio stagno e piombo. Il colore delle patine, l'analisi elementale con XRF e SEM-EDS, e l'analisi composizionale con XRD e FTIR-ATR permettono di identificare i composti sia amorfi che cristallini di cui sono formate le patine. Mediante l'XRF si evidenzia il fenomeno della decuprificazione e l'arricchimento in superficie degli elementi alliganti. Il rapporto tra le intensità delle righe di fluorescenza L e K dello stagno (M e L del piombo) può essere utilizzato per verificare l'avanzamento del fenomeno corrosivo, poiché dipende sia dallo spessore degli strati di corrosione che dall'arricchimento superficiale di questi elementi. La presenza del cloro nelle patine verdi, rivelabile con l'XRF, ed alcuni aspetti morfologici osservabili al microscopio consentono di palesare il fenomeno del "cancro del bronzo". Infine è stato riscontrato che monete di lega simile, rinvenute nella stessa unità stratigrafica, non presentano gli stessi prodotti di corrosione, la cui formazione probabilmente è stata influenzata da microambienti differenti.

Ministero per i Beni e le Attività Culturali, Servizio Tecnico Ricerche Antropologiche e Paleopatologicbe, Roma; 2Jstituto Universitario Suor Oisola Benincasa, Napoli; 3Università La Sapienza, Dip. Fisica, Roma; "'stituto Centrale per n Restauro, Roma

Energy-dispersive x-ray fluorescence (EDXRF) analysis is particularly suited to analyse paintings, because of its non destructive manner and multi-elemental capacity. Interestingly, it can be conducted with portable equipment. The mean penetration of incident and secondary radiation has the same order of magnitude as the pigments thickness;