[en] A set of fragments of metallic artefacts from the medieval period excavated from Ciudad Real in Spain has been studied. The objects are gilded copper buckles with a champleve enamelling decoration. The composition of predominantly blue-coloured enamels has been analysed using three non-destructive techniques, SEM-EDAX (scanning electron microscopy coupled with energy-dispersive X-ray analysis), X-ray fluorescence (XRF) and PIXE (particle-induced X-ray emission). Analyses show that Co is responsible for the blue colour. The results of the two techniques are compared, as well as the main components which constitute the enamel. Analyses suggest that Cu is responsible for red colour. (orig.)

[en] Since the 1990's, artificial treatment of natural sapphires (Al₂O₃ crystals coloured by impurities) by diffusion of beryllium at high temperature has become a growing practice. This process permits to enhance the colour of these gemstones, and thus to increase their value. Detection of such a treatment - diffusion of tens of μg/g of beryllium in Al₂O₃ crystals - is usually achieved using high sensitivity techniques like laser-ablation inductively coupled plasma mass spectrometry (LA-ICP/MS) or laser-induced breakdown spectrometry (LIBS) which are unfortunately micro-destructive (leaving 50-100-μm diameter craters on the gems). The simple and non-destructive alternative method proposed in this work is based on the nuclear reaction ⁹Be(α, nγ)¹²C with an external helium ion beam impinging on the gem directly placed in air. The 4439 keV prompt γ-ray tagging Be atoms are detected with a high efficiency bismuth germanate scintillator. Beam dose is monitored using the 2235 keV prompt γ-ray produced during irradiation by the aluminium of the sapphire matrix through the ²⁷Al(α, pγ)³⁰Si nuclear reaction. The method is tested on a series of Be-treated sapphires previously analyzed by LA-ICP/MS to determine the optimal conditions to obtain a peak to background appropriate to reach the required μg/g sensitivity. Using a 2.8-MeV external He beam and a beam dose of 200 μC, beryllium concentrations from 5 to 16 μg/g have been measured in the samples, with a detection limit of 1 μg/g.

[en] Numerous metallic objects with very aesthetic and technological qualities have been recovered by archaeological excavations. Adequate processes of restoration and conservation treatments require the accurate determination of the elemental composition and distribution within the objects, as well as the identification of the nature and distribution of the corrosion products. Ideally the identification method should cause no alteration in the sample. In this work, different archaeological pieces with a gilded look have been characterized using simultaneously PIXE and RBS at the CMAM external microprobe in order to study the gilding metalworking done in the Iberian Peninsula during the Middle Ages. The gold layer thickness and its elemental concentrations of Ag, Au and Hg were determined by both techniques and compared with the scanning electron microscopy images obtained for some fragments of pieces. (orig.)

[en] Up to now, among the IBA techniques, only PIXE has been used for analyzing paintings. However, quantitative PIXE analysis is sometimes difficult to interpret due to the layered structure, the presence of varnish and organic binder and, in some cases, discoloration of the pigments has been observed due to the interaction of the ion beam with the compounds. In order to improve the characterization of paintings, we propose some alternative experimental procedures. First of all, backscattering spectrometry (BS) and PIXE are simultaneously combined in order to collect complementary information such as layer thickness and organic compound quantification. The simultaneous PIXE and BS experiments also have the advantage of being able to analyze the same area in one experiment. This combination, implemented with an external beam, was directly applied on paintings and on painting cross-sections for the study of Italian Renaissance masterpieces. We have obtained valuable results not only on the pigment itself but also, for the first time, on the binder to pigment proportion which is not well documented in the ancient recipes. Moreover, in order to restrain beam damages due to the ion stopping power, we propose to analyze very thin painting cross-sections by a combination of PIXE-RBS and Scanning Transmission Ion Microscopy (STIM).

[en] The visigothic treasure of Torredonjimeno (Jaen, Spain) was found by chance in the year 1926 buried in an olive grove. The finding consisted of some hundreds fragments of gold objects and gems coming from several votive crowns and crosses, some of them belonging to an unidentified visigothic king. The treasure may belong chronologically to the same period as the Guarrazar treasure or, possibly, to a somewhat later time, but the pieces are fragmented and of less technological workmanship than the latter. This is the reason why the Torredonjimeno treasure has not attracted as much attention from archeologists and art historians as that from Guarrazar. On the occasion of an exhibition showing together all the objects of the treasure, it is normally kept in three different museums in Barcelona, Cordoba and Madrid, a number of pieces were analyzed, using PIXE, PIGE and RBS, at the external microbeam facility installed at the Center for Micro-Analysis of Materials