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Non-destructive elemental analysis on objects d’art

Non-destructive elemental analysis on objects d’art. Ion Beam Laboratory ISL. Paintings. Andrea Denker Ionenstrahllabor Hahn-Meitner-Institut Berlin. Metal Objects. Art Historical Motivation. Analysis: PIXE . Conclusions. Ionenstrahllabor, Hahn-Meitner-Institut Berlin.

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Non-destructive elemental analysis on objects d’art

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  1. Non-destructive elemental analysis on objects d’art Ion Beam Laboratory ISL Paintings Andrea Denker Ionenstrahllabor Hahn-Meitner-Institut Berlin Metal Objects Art Historical Motivation Analysis: PIXE Conclusions Ionenstrahllabor, Hahn-Meitner-Institut Berlin

  2. Ionenstrahllabor ISL: ion beam laboratory RFQ + Cyclotron CN + Cycl. • laboratory for ion beam applications • internal and external (~ 70%) users • ion energy: eV < Eion< 800 MeV • research areas: • materials modificationion-solid-interaction • medical applications • materials analysis

  3. ISL: Accelerators + Target Stations 14 dedicated target stations

  4. ion solid interaction • rotation during irradiation: “nano-towers” ion beam induced self organisation: • lamella structure on NiO/SiO2/Si-Wafer with increasingfluence (230 MeV Xe): • incidence angle 75°,height ~ 1 µm, width ~ 100 nm(Bolse et al., Appl. Phys. A 77, 11–15 (2003))

  5. materials modification Ion Track Membrane irradiation stopping drying etching rinsing result: filter with defined structure, cylindrical or hour-glass like pores with huge aspect ratio collaboration with industry Gore-Membrane 3 µm

  6. eye tumour therapy in collaboration with Charité • 1991: first contacts • April 1995: financing granted • Mai 1995: laying of the cornerstone • August 1997: technical completion • 13.06.1998 authorisation • 22.06.1998 first patient today: more than 750 patients • 85% choroidal melanomas: - 97.8% tumour control - 95.0% eye retention • 6% iris melanomas: no relapses • 5% choroidal haemangioma: no relapses line ofvision proton beam

  7. Materials Analysis – ERDA: Principle projectile Mp E0 ER MR f target atom q Mp Elastic Recoil Detection Analysis: • irradiation of the sample with heavy high energetic ions at grazing incidence • coincident measurement of energy and time-of-flight of the out-scattered atoms from the sample • pulsed heavy-ion beam (e.g. Kr, Xe, Au) with  1.7 MeV/u

  8. Materials Analysis – ERDA: Example Ti/Al multilayeron steel, 5 double layers of 150 nm Al and 100 nm Ti scatterplot: time-of-flight versus energy 350 MeV 197Au

  9. art historical motivation: the issues 19th century or older? massive or gilded? manu-facturing age Archaeology/ Art History authenticity provenience attribution toworkshops Ming orforgery? conservation/restoration decrease of copperin silver coins

  10. motivation: 19th century painting • many copies of Allori, even by himself • this copy:unknown artist19th century?? • quality of painting:(brushstroke...)  much older ? Christofano Allori (1615) Pitti Palace, Firenze trust collection, Berlin

  11. motivation: 19th century or much older? • stylistic evaluation not sufficient • looking for more “solid” arguments: chronology of pigments • collaboration with restorators/art historians

  12. motivation: info by element identification indirect dating(pigments used) techniquemassive or gilded? manu-facturing age Archaeology/ Art History authenticity provenience Ming orforgery?(colours) attribution toworkshops(metals used) conservation/restoration determination of Cu content

  13. motivation: analytical techniques impossible possible objects valuable, unique • required: non-destructive! • object remains in normal atmosphere • no sampling • no traces • Proton Induced X-Ray Emission (PIXE) • X-Ray Fluorescence analysis (XRF) sampling

  14. PIXE: Proton Induced X-Ray Emission Louvre excitation of characteristic X-rays by proton irradiation • multi elemental analysis • in vacuum from Na, in air from K no organic materials • determination of elements, not type of binding lead tin yellow - chromium yellow Malachite(green) (CuCO3·Cu(OH)2) - Azurite(blue) (2 CuCO3·Cu(OH)2) • non-destructive: in air and low proton intensities • standard technique: proton energies up to 4 MeV • Louvre museum has a dedicated 2 MV accelerator for ion beam analysis

  15. PIXE (Ep = 1 and 4 MeV) compared to XRF PIXE pros • detection limit: down to µg/g(determined by sample and element looked for) • depth information by variation of proton energy • low background PIXE cons • object has to be transported to accelerator • maximal analytical depth:ca. 70 µm XRF pros • detection limit: 10 µg/g(determined by sample and element looked for) • portable equipment XRF cons • high background • maximal analytical depth150 µm

  16. High Energy PIXE • 3 MeV 68 MeV • air 140 mm 33 m • C 0.75 mm 20 mm • Cu 33 µm 7 mm • d1/2 Pb La Pb Ka • in C 2 mm 24 mm • in Cu 4.5 µm 800 µm analytical depth up to several mm • large range of protons • depth dependant info:line ratios • radiation from all material, also nuclear reactions Þ higher background • large cross section for K lines of heavy elements, better separation, less absorption • small energy loss Þ non-destructiveÞ cross sections constant over large depth

  17. high-energy PIXE: analysis up to several mm • background bearable • Pb glass  Pb K linesbackground from sample • 30 µm gold foil behind3 mm Pb glass gold signal evident

  18. PIXE : Set-up • analysis of art objects: proton beam in air • small straggling: large and bulky objects • HPGe: 180 eV @ 5.9 keV • laser forpositioning • proton intensity:< 0.1 pA • measuring time:~ 200 s • video camerasurveys anddocuments beam spot

  19. measurements: standards 25 mm • measurements on standards with certified composition: • steel (BAM 290-1); 1.88 mm and 26 mm thick • lead bronze (BAM 374); 1.52 mm and 23.5 mm thick • brass (BAM 375); 1.84 mm and 25.5 mm thick • Cu + traces (BAM 376); 1.62 mm and 22.8 mm thick • thick and “thin” samples from the same material • energy loss in “thin” sample: ~ 9 MeV, i.e. exit energy 59 MeV 90% of X-rays • thick samples: protons stop • in addition:5 mm thick Cu/Ag alloys from ÖGUSSA • analysing software: GUPIX

  20. measurements: “thin” standards - results 0.3 0 58.3 38.2 0 2.9 K = K lines used 1.9 4.2 0 76.6 5.8 0.9 0 4.7 5.8 0.2 K Pb K lines: radioactive source in radiation monitor nearby brass BAM 375 1.84 mm (values in %) Fe Ni Cu Zn Sn Pb 0.21 0.11 58.32 38.02 0.21 2.90 0.3 0 58.6 38.3 0.2 2.7 L = L lines used steel BAM 290-1 1.88 mm (values in %) V Cr Mn Fe Co Ni Cu Mo W Pb 1.91 4.18 0.24 76.03 5.12 0.33 0.08 4.83 6.27 - 1.9 4.3 0 76.5 5.8 0.9 0 4.7 5.9 0 L

  21. paintings: the challenges possible structure of a painting: • support (canvas, wood…) • ground (chalk, gypsum) • imprimatura • underpainting • paint layer • highlight problem: paintings are not technical samples • layers vary in thickness • layers interfere  precise determination impossible but: that is not needed!

  22. depth depending information • collaboration with the Kunsthistorische Museum Wien (Dr. M. Griesser, H. Musner) • 12 paint mock-ups using techniques of Italian and Flemish artists, 16./17. century • analysed using PIXE, estimation of sequence and thickness from Ka/Kb, La/Ka, La/Lb ratios • preparation of cross sections and analysed using a microscope

  23. depth depending information layer element depth cross section PIXE chalk ground Ca ≥ 110 µm no depth info. yellow ochre Fe 50-110 µm 70/110 µm Azurite Cu 10-100 µm 20/ 30 µm lead white Pb 5-10 µm 5/ 20 µmhighlight • works well for „easy“ sequences • ambiguities possible  interpretation only in collaboration with art historians

  24. Allori copy • analytical task: identification of pigments (indirect dating by pigment chronology) • paint layers > 100 µm thick Þ high proton energies necessary • in total: 15 different spots analysed on the painting

  25. Allori copy • Judith’s cloth, white: • Pb, traces of Fe Þ lead white • no Ti, Zn, Ba Þ modern pigments can be excluded • Judith’s cloth, yellow: • Fe, Pb, traces of Ca • from Fe Ka/Kb: iron on top of leadÞ most probably yellow ochre on lead white • no Cd, Cr ... Þ modern pigments can be excluded • Holofernes’ face, light brown • some Fe, Pb Þ most probably ochre mixed with lead white • stripe in girdle, blue • Pb • no Fe: Prussian blue (after 1735) can be excluded • no Co: modern pigments excluded • blue colour due to Indigo or Ultramarine (Na,Al-compound)

  26. Flemish Painting • adoration of the shepherds, 17. century, unknown artist, Gemäldegalerie Berlin • at HMI investigated with neutron autoradiography:yields distribution for Cu, Mn, Hg…..„blind“ for Pb, Ca, Sn, Fe (chalk, ochre, Pb-Sn-yellow, Pb-white) • aim of PIXE:supplemental information • blue in sky: Fe, Pb, Co, As, Cu Smalte • blue in window: Fe, Pb, Cu

  27. Flemish Painting • red coat:Fe, Pb, Hg  Cinnabar • yellow coat:Fe, Pb, Sn  lead-tin-yellow • lead on dark spots in large depth lead-white ground • confirmation of neutron autoradiography results • additional information for Fe and Pb • identification of yellow: lead-tin-yellow

  28. Modigliani Portrait • Portrait,attributed to Modigliani • X-ray image shows second picture underneath • one or two artists?

  29. Modigliani Portrait • broad palette of pigments:Fe, Zn, Cd, Ba, and Pb in various amountson some spots Cr, Se, Hg • problem with Ti: Ba La: 4.47 keV Ti Ka: 4.51 keVBa Lb: 4.83 keVTi Kb: 4.93 keV • Pb in largerdepth

  30. Prussian Medal • Prussian Medal, about 1790 Deutsches Historisches Museum, Berlin • weighing impossible: massive object? gilded? • t = 200s, Ip ~0.1 pA • result: medal: La/Ka = 1.09 1 µm Au-foil: La/Ka ~ 40, ~ 75% Au~ 15% Ag~ 10% Cu

  31. Wiener Pfennig: Hoard of Tulln • medieval silver/copper-coin, annual change of imprint, from 1110/20 until 1395 • first analysis in 19. century:melting of coins and chemical analysis • 1983: chronological ordering by Bernhard Koch • Tulln 1990: 10394 „Wiener Pfennige“ (8724 g) in one ceramic vase • strong corrosion: all coins corroded to one block • coins extracted • restoring necessary, chemically cleaned with acids

  32. Wiener Pfennig: the analytical problem idea: determine the copper content in the hoard of Tulln to verify assumption of decreasing silver contentproblem: light element (Cu) in heavy matrix (Ag) strong absorption of Cu-signal nuclear reaction:63Cu(p,3n)61Zn61Zn  61Cu  61Ni*:67.4 keV g lineProton Inducedg-ray Emission 2 informations: • Cu X-ray: 10 µm • Cu g line: 300µm

  33. Wiener Pfennig, results from Cu Ka • measured: 330 coins from the hoard of Tulln • calculation of concentration using X-rays (concentrations close to surface) • result: 93 % Ag 5 % Cu2 % Pb • contradictionto data of19. century

  34. Wiener Pfennig, results from Cu g-line • calculation of Cu content using g-line (larger analytical depth) • result: higher Cu concentrations than on surface • yet: larger statistical errors • 293 coins of other findings • grouping of coins with the same minting yearand origin: proof of Cudepletion close to surface

  35. Medieval brooches • 630 - 660: used by noble ladies for coatsiron with silver and gold coloured decoration, diameter: about 5 cm • 1940 - 1973: excavation of the grave field in Eltville (646 graves) one of the largest in Germany • 1955 - 1975: restoration of the objects technique of the time: stabilisation and corrosion protection by plastic cover (about 1mm thick) • today: removal of plastic impossible (destruction risk)

  36. Medieval brooches plasticcopper 0 1 2 3 4 5 6 7 8 depth (mm) • range of 4 MeV protons in plastic: ~ 0.25 mm • use of 68 MeV protons: • energy loss in 1 mm plastic (r » 1 g/cm3): ~ 1 MeV • small lateral straggling • transmission after 1 mm: Fe Ka 6.4 keV 20%Cu Ka 8.0 keV 46% Pb La 10.5 keV 69% Ag Ka 22.0 keV 93% • absorption no principal problem • only qualitative analysis protons X-rays

  37. Medieval brooches rivet head rivet cap plastic cover ornaments iron inlay dose rivet needle today: 19 brooches excavated 3 lost (World War II) identification of metals on 8 brooches: • doses made of brass • confirmation: inlay made of iron • decoration made of silver and Cu/Zn/Ag alloy  sophisticated objects, for noble people,yet: productionwithout gold

  38. Egyptian coffin mask • gilded wood • queen Satdjehuti 1600 B.C. • excavated about 100 years ago, private ownership • status excellent - repaired? • sensitive object, difficult to position • investigated on 21 points • on nearly all points:> 92 % Au, ca. 6% Ag, 1% Cu, (river gold) at least 1.5 µm • thickness and composition Þ original gilding mask now in the Staatlichen Sammlung ägyptischer Kunst, München

  39. Egyptian scarab appeared during World War II is it real? • investigated on 3 points • ca. 95 % Au, ca. 5% Ag, (river gold), massive • additional: synchrotron XRD on the eyes  no glass  most probably: true ancient object

  40. Chinese bowl: manufacturing date? report 1 (Japan): 500 years old 1 Mio. € • both reports based on art historical expertise • indirect dating: identification of pigments (Cr in green: after 1850) 20 cm report 2 (Berlin): 100 years old max. 25 000 €

  41. Chinese bowl • porcelain extremely sensitive • high-energy protons: small risk of damage due to low proton intensity and small dE/dx • on bowl: Pb (flux) and Cu (pigment) • modern porcelain: Cr (pigment) • green colour no information • yellow colour measured: modern pigment detected Þ report 2 could beconfirmed

  42. Conclusion I all these results could only be obtained thanks to fruitful collaborations with the following people: • Ägyptisches Museum und Papyrussammlung Berlin, Prof. D. Wildung • Fachhochschule für Technik und Wirtschaft Berlin, K. Ebert • Skulpturensammlung Berlin, Dr. K. Achilles-Syndram • Rathgenforschungslabor Berlin, Dr. C. Goedicke, Prof. J. Riederer • Universität of Marburg M.A. M. Blaich • Kunsthistorische Museum Wien Dr. M. Griesser, H. Musner, R. Denk, H. Winter

  43. Conclusion II the features of high-energy PIXE are • elements heavier than Ca are detected • non-destructive • unique for thick layers • allows analysis of sensitive and bulky objects • fast method: qualitative results after a few minutes more than 2000 objects analyzed • coins • brooches • sculptures • paintings • ….. fascinating interdisciplinary field Thank you for your attention!

  44. The Result of the Evaluation Process evaluation and recommendation of the referees • In order to fulfil its mission, a facility with the necessary excellent performance … was very successfully created. • We are particularly worried about the understaffing of ISL and, therefore, recommend an increase of staff there, to allow them to increase the available beam time in order to respond to a growing demand in the field of materials modification. Helmholtz Senate (Sep. 04):close down ISL until end of 2007 HMI supervisory board (Nov. 04): close down ISL until end of 2006 at the moment: negotiations to save eye tumour therapy

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