References of "Strivay, David"
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See detailNatural radioactivity and elemental composition of sands in the Douala region, Littoral of Cameroon Using Portable XRF and HPGe detector
Guembou Shouop, Cébastien Joel ULg; Ndontchueng Moyo, Maurice; Chene, Grégoire ULg et al

Poster (2016, June 21)

Twenty four sand samples from seven sand quarries alone the Gulf of Guinea, Douala Littoral region of Cameroon, were analyzed using high purity germanium detector and a portable X-ray fluorescence (PXRF ... [more ▼]

Twenty four sand samples from seven sand quarries alone the Gulf of Guinea, Douala Littoral region of Cameroon, were analyzed using high purity germanium detector and a portable X-ray fluorescence (PXRF) spectrometer. A comprehensive study was conducted to determine the natural radioactivity concentrations and the geological provenience of sand samples from seven different quarries sites of the Douala, a popular city, and its surroundings. The radioactivity investigation was performed by using high resolution gamma-ray spectrometry. From the measured gamma-spectra, the average activity concentrations were determined for 226Ra, 232Th, 40K and 235U for a depth of 5–25 cm. Results of this study were compared to values from other locations around the world. X-ray fluorescence spectrometry (XRF) measurements were performed for the quantitative elemental analysis of the sands, revealing the major, minor and trace elements present in the investigated samples. Reference marine and geological sample are used to check precision and accuracy of the equipment for major and minor components. From XRF experimental results it was possible to estimate the geological provenience of the analyzed sands. These data record the radioactivity background levels in sands and could be used as reference information in Cameroon. The comparison of major (Si, Al), minor (K, Ca,Fe), and trace (Ti, Mn, Zr, Rb, Sr) element ratios was made. The results indicate that the levels of Si and Al can be very helpful in subgroup definition and provide useful clues to the raw materials used for glassmaking in Cameroon. [less ▲]

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See detailDevelopment of a translation stage for in situ non-invasive analysis and high resolution imaging
Strivay, David ULg; Clar, Mathieu ULg; Rakkaa, Saïd ULg et al

Poster (2016, March)

Non-invasive imaging techniques and analytical instrumentation for cultural heritage object studies have undergone a tremendous development over the last years. Many new miniature and/or handheld systems ... [more ▼]

Non-invasive imaging techniques and analytical instrumentation for cultural heritage object studies have undergone a tremendous development over the last years. Many new miniature and/or handheld systems have been developed and optimized. Nonetheless, these instruments are usually used with a tripod or a manual position system. This is very time consuming when performing point analysis or 2D scanning of a surface. The Centre Européen d’Archéométrie (CEA) has build a translation system made of pluggable rails of 1 m long with a maximum length and height of 3 m. Three motors embedded in the system allow the platform to be moved along these axis, toward and backward from the sample. The rails hold a displacement system, providing a continuous movement. Any position can be reached with a reproducibility of 0.1 mm. The displacements are controlled by an Ethernet connection through a laptop computer running a multiplatform homemade software written in JAVA. This software allows a complete control over the positioning using a simple, unique, and concise interface. Automatic scanning can be performed over a large surface of 3 meters on 3 meters. The Ethernet wires provide also the power for the different motors and, if necessary the detection head. The platform has been originally designed for a XRF detection head (with its full power alimentation) but now can accommodate many different systems like IR reflectography, digital camera, hyperspectral camera, Raman probes, etc. The positioning system can be modified to combine the acquisition software of the imaging or analytical techniques and the positioning software. [less ▲]

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See detailDevelopment of a translation stage for in situ noninvasive analysis and high-resolution imaging
Strivay, David ULg; Clar, Mathieu ULg; Rakkaa, Saïd ULg et al

in Applied Physics A : Materials Science & Processing (2016), 122

Non-invasive imaging techniques and analytical instrumentation for cultural heritage object studies have undergone a tremendous development over the last years. Many new miniature and/or handheld systems ... [more ▼]

Non-invasive imaging techniques and analytical instrumentation for cultural heritage object studies have undergone a tremendous development over the last years. Many new miniature and/or handheld systems have been developed and optimized. Nonetheless, these instruments are usually used with a tripod or a manual position system. This is very time consuming when performing point analysis or 2D scanning of a surface. The Centre Européen d’Archéométrie has built a translation system made of pluggable rails of 1 m long with a maximum length and height of 3 m. Three motors embedded in the system allow the platform to be moved along these axis, toward and backward from the sample. The rails hold a displacement system, providing a continuous movement. Any position can be reached with a reproducibility of 0.1 mm. The displacements are controlled by an Ethernet connection through a laptop computer running a multiplatform custom-made software written in JAVA. This software allows a complete control over the positioning using a simple, unique, and concise interface. Automatic scanning can be performed over a large surface of 3 m on 3 m. The Ethernet wires provide also the power for the different motors and, if necessary, the detection head. The platform has been originally designed for a XRF detection head (with its full power alimentation) but now can accommodate many different systems like IR reflectography, digital camera, hyperspectral camera, and Raman probes. The positioning system can be modified to combine the acquisition software of the imaging or analytical techniques and the positioning software. [less ▲]

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See detailDevelopment of a Reference Database for Particle-Induced Gamma-ray Emission spectroscopy
Dimitriou, P.; Becker, H.-W.; Bogdanović-Radović, I. et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2016), 371

Particle-Induced Gamma-ray Emission (PIGE) is a powerful analytical technique that exploits the interactions of rapid charged particles with nuclei located near a sample surface to determine the ... [more ▼]

Particle-Induced Gamma-ray Emission (PIGE) is a powerful analytical technique that exploits the interactions of rapid charged particles with nuclei located near a sample surface to determine the composition and structure of the surface regions of solids by measurement of characteristic prompt γ rays. The potential for depth profiling of this technique has long been recognized, however, the implementation has been limited owing to insufficient knowledge of the physical data and lack of suitable user-friendly computer codes for the applications. Although a considerable body of published data exists in the nuclear physics literature for nuclear reaction cross sections with γ rays in the exit channel, there is no up-to-date, comprehensive compilation specifically dedicated to IBA applications. A number of PIGE cross-section data had already been uploaded to the Ion Beam Analysis Nuclear Data Library (IBANDL) (http://www-nds.iaea.org/ibandl) by members of the IBA community by 2011, however a preliminary survey of this body of unevaluated experimental data has revealed numerous discrepancies beyond the uncertainty limits reported by the authors. Using the resources and coordination provided by the IAEA, a concerted effort to improve the situation was made within the Coordinated Research Project on the Development of a Reference Database for PIGE spectroscopy, from 2011 to 2015. The aim of the CRP was to create a data library for Ion Beam Analysis that contains reliable and usable data on charged particle γ-ray emission cross sections that would be made freely available to the user community. As the CRP has reached its completion, we shall present its main achievements, including the results of nuclear cross-section evaluations and the development of a computer code that will become available to the public allowing for the implementation of a standardless PIGE technique. © 2015 Elsevier B.V. All rights reserved. [less ▲]

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See detailOn the processing of red pigment by late mousterian Neanderthals in Ormesson, Seine-et-Marne, France, 47000 years ago
Salomon, Hélène ULg; Bodu, Pierre; Geurten, Stéphanie et al

E-print/Working paper (2016)

Detailed reference viewed: 36 (8 ULg)
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See detailRecent technical developments of non-invasive cultural heritage analysis at the University of Liège
Strivay, David ULg; Chene, Grégoire ULg; Calvo Del Castillo, Helena ULg et al

Conference (2015, December 07)

The University of Liège has more than twenty years of experience in the use of ion beam analysis techniques for cultural heritage research. We will present here some of the recent developments. First, we ... [more ▼]

The University of Liège has more than twenty years of experience in the use of ion beam analysis techniques for cultural heritage research. We will present here some of the recent developments. First, we have developed a high energy extracted beamline up to 20 MeV on our cyclotron with a good energy resolution of a few keV. These last years Ion Beam Analysis users show an interest in High Energy Alpha beam. These beams can be used for on-site analysis by means of radioactive sources e.g. for space application but they also offer a powerful combination of properties for the analysis of thick layers (about 10 to 20 µm). This kind of layers are often met in cultural heritage applications but can be also present on new materials. Contrary to this kind of materials where the principal information needed is the in-depth profiles as the sample are of known composition, for cultural heritage materials the combination of elemental analysis and their in-depth distribution is essential as the nature of the material is a-priori not known. We will also present the development around our first extracted beamline. We have indeed improved the automatic scanning system for macro-PIXE. Some examples will be shown. Finally we will show other non-invasive analysis developments related to cultural heritage. [less ▲]

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See detailEarly medieval glass tiles from Saint-Sauveur (Burgundy, France)
Van Wersch, Line ULg; Mathis, François ULg; Bonnin, Myrtho et al

Conference (2015, September 09)

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See detailMacro-XRF scanning in archaeological and museum sites: pros and cons
Strivay, David ULg

Conference (2015, July 09)

Detailed reference viewed: 18 (2 ULg)
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See detailPrehistoric and Renaissance art, a comparative review of analytical techniques
Strivay, David ULg

Conference (2015, April 10)

Detailed reference viewed: 8 (0 ULg)
See detailUnraveling expressionism
truscott, tadd; Darbois-Texier, Baptiste ULg; lovett, benjamin et al

Conference (2015)

Detailed reference viewed: 47 (4 ULg)
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See detailTowards portable X-ray spectroscopic imaging of Palaeolithic cave art. Insights into used pigments and wall taphonomy at three Palaeolithic key cave sites
Gay, Marine; Muller, Katharina; Plassard, Frédéric et al

Poster (2014, May)

Palaeolithic cave art has taken a more and more important place in our cultural heritage. Its preservation is one of the major issues and involves necessarily a better understanding of the cave ... [more ▼]

Palaeolithic cave art has taken a more and more important place in our cultural heritage. Its preservation is one of the major issues and involves necessarily a better understanding of the cave environments and of their evolution over time. However, the on-site geo-physico- chemical study of archaeological record stays dif cult and the conservation of its integrity imposes restrictions. Taking bene t of recent analytical developments in the X-ray eld, new perspectives of acquiring statistically relevant data for archaeological interpretation directly in the eld are provided by the implementation of portable and non-invasive characterization methods. It allows the improvement of archaeological and physico-chemical knowledge about the pigments used, the evaluation of the state of wall decorated surfaces over time and a better assessment of the relationship between pigment and wall support. For these purposes, complementary self-built portable spectrometers (X-ray uorescence in one and two dimensional mode, X-ray diffraction) are combined to perform qualitative and quantitative characterization of the pigments and cave walls as well as for chemical imaging on a decimetre scale. By using this combination of portable instruments the feasibility of analysis under very dif cult conditions speci c to the cave environments (humidity, temperature, dif cult access to the caves and to the decorated panels) was shown. Special spectrum evaluation procedures have been developed to take into account the heterogeneity of the cave walls in order to gain reliable data for chemical characterisation. The ef ciency of the analytical procedure has been demonstrated for three major cave sites featuring Palaeolithic art: Font-de-Gaume and Rouf gnac cave in Dordogne (France) and La Garma in Cantabria (Spain). A large assortment of colours can be observed in these caves (red, black, yellow and purple), associated to different mineral phases (iron and/or manganese oxides, charcoal and mixtures). Their detailed characterization provides an improved comprehension of the pictorial techniques used. Furthermore, it allows a better comparison between representations in a same cave, giving more detailed insights into its pictorial homogeneity and the different execution phases of its gures. As an example, the results obtained at Rouf gnac cave showed that heterogeneous mixtures of manganese oxides have been employed to design the 65 Great Ceiling gures whereas a unique pigment mixture has been used for the drawing of the Ten Mammoths Frieze. Further information has been obtained on the taphonomic wall processes. The spectroscopic study of these cave art illustrate the strong potential of such combined in situ and non-invasive analyses to better characterize the prehistoric gures in their cave environment and in a wider perspective to better understand the symbolic practices of past societies, appreciate possible cultural changes and relationships within the Franco-Cantabrian region. [less ▲]

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See detailÉtude technique et matérielle des tableaux liégeois
Defeyt, Catherine ULg; Strivay, David ULg

in Duchesne, Jean-Patrick (Ed.) L'art dégénéré selon Hitler (2014)

Les études dans le domaine du patrimoine culturel peuvent généralement se ranger en deux catégories. La première catégorie concerne les analyses physico-chimiques qui visent à une meilleure compréhension ... [more ▼]

Les études dans le domaine du patrimoine culturel peuvent généralement se ranger en deux catégories. La première catégorie concerne les analyses physico-chimiques qui visent à une meilleure compréhension de l'œuvre via le gain d'information sur les matériaux utilisés et la technologie mise en œuvre. Ces données peuvent conduire à une datation de l'objet et à l'identification de son origine géographique et permettent de documenter l'évolution et l'histoire des techniques artistiques. La seconde classe de ces études archéométriques se focalise sur l'état de conservation de l'œuvre et sur l'origine de ses éventuelles altérations apparues au cours du temps. L'objectif est donc d'identifier ces mécanismes de dégradations car ces dernières peuvent significativement altérer la perception de l’œuvre et compliquer le travail de restauration, dont le but premier est de respecter l’intention initiale de l’artiste. Le but ultime de ce type d'études est d'optimiser les conditions de conservation des œuvres existantes et d'améliorer la durabilité des matériaux artistiques modernes qui seront utilisés dans le futur. Le Centre Européen d’Archéométrie de l’Université de Liège, fondé en 2003, s’est spécialisé dans l’étude du patrimoine culturel mobilier et immobilier. La bonne conduite des projets de recherches menés au Centre d’Archéométrie nécessite une étroite collaboration entre scientifiques et archéologues, conservateurs et historiens d’art. Le centre se veut un acteur dynamique dans la conservation du patrimoine culturel belge. Pour ce faire, il est nécessaire de dresser un premier bilan de l'état des objets conservés et de poser un diagnostic de leur état de conservation. Dans de nombreux cas, il est très difficile, voire inconcevable, de déplacer ou de prélever les objets du patrimoine culturel étudiés. C’est pourquoi les recherches sur les techniques d’analyse non invasives et mobiles connaissent un développement très important ces dernières années. Actuellement, l’utilisation combinée de plusieurs techniques mobiles, telles que la fluorescence X, la diffraction X, la spectroscopie Raman ou infrarouge à transformée Fourier reste très restreinte et peu exploitée lors des campagnes d’analyses in situ. La plateforme d’instruments portables du Centre Européen d’Archéométrie permet de documenter de manière complète et systématique les œuvres des collections et de poser un constat de l’état de conservation et d’altération de ces objets. Dans le cadre du partenariat de recherche entre le CEA et les musées de la Ville de Liège récemment mis en place et grâce à un financement du Fonds Jean-Jacques Comhaire (Fondation Roi Baudouin), nous avons étudié les tableaux de la vente de Lucerne de 1939. Ces œuvres majeures ne peuvent être déplacées et ont donc été étudiées par des méthodes mobiles. L'utilisation de la plate-forme expérimentale mise en place au Centre Européen d’Archéométrie a permis d'identifier les matériaux utilisés et de caractériser les techniques picturales des différents artistes. Nous montrons ici les résultats concernant les tableaux de Paul Gauguin, Pablo Picasso et James Ensor. [less ▲]

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See detailPB15 as 20th and 21st Artists’ Pigments: Conservation Concerns
Defeyt, Catherine ULg; Strivay, David ULg

in E‐Preservation Science (2014), 11

Copper phthalocyanine (CuPc) provides the most important blue and green pigments from the 21st century artists’ paints. This paper focuses on the blue pigments of CuPc, which are referenced in the Colour ... [more ▼]

Copper phthalocyanine (CuPc) provides the most important blue and green pigments from the 21st century artists’ paints. This paper focuses on the blue pigments of CuPc, which are referenced in the Colour Index as PB15. The employment of PB15 as artists’ pigments since the very beginning until now is summarized through archives of artists’ color makers and current color charts. Moreover, for the first time, a review of the cases of PB15 identifica- tion encountered in the field of cultural heritage is presented. For each case reported in this study, the analytical methods that allowed identifying the blue pigment are specified. The significance and the relevance of various destructive and non-destructive methods, for this topic in particular are also discussed. Finally, the implications of PB15 in common conservation prac- tices are outlined. [less ▲]

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See detailDistinction by micro-Raman spectroscopy and chemometrical analysis of copper phthalocyanine blue polymorphs in oil-based and acrylic samples
Defeyt, Catherine ULg; Van Pevenage, Jolien; Learner, Tom et al

in Van den berg, K.J.; Burnstock, A.; de Tagle, A. (Eds.) et al Issues in Contemporary Oil Paints (2014)

Copper phthalocyanine (CuPc) blue, commonly named phthalo blue is the most important synthetic organic blue pigment in the 20th and 21st century artists paints. Phthalo blue, which is adopted by artists ... [more ▼]

Copper phthalocyanine (CuPc) blue, commonly named phthalo blue is the most important synthetic organic blue pigment in the 20th and 21st century artists paints. Phthalo blue, which is adopted by artists since 1936, is a polymorphous pigment. Currently, the alpha, beta and epsilon CuPc polymorphs are used in artists paint formulations. The identification of the CuPc crystal form provides technical and chronological information relevant for studying artworks. Raman Spectroscopy (RS) is a very valuable technique for the detection of phthalo blue in paint layers. However, the spectral interpretation is not straightforward concerning the CuPc polymorph distinction. To overcome the problem we have previously developed a procedure combining RS and chemometrical analysis. The experimental results that we obtained have demonstrated its efficiency for predicting the CuPc crystal form in unknown paint samples. In the present work, this procedure was applied on oil-based and acrylic paints from Sam Francis’ studio and the Getty Conservation Institute (GCI) Reference Collection. [less ▲]

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