Particle Accelerators in Art and Archaeology

Particle Accelerators in Art & Archaeology Pier Andrea Mandò Dipartimento di Fisica and Sezione INFN, Florence, Italy e-mail mando@fi.infn.it Erice, April 17, 2004 Nuclear Physics for the Cultural Heritage • material analysis by IBA techniques • dating of finds by the radiocarbon (14C) method Both available at the new INFN laboratory in Florence Ion Beam Analysis • A set of powerful techniques for the compositional analysis of any material • Based on the emission of characteristic radiation, which is induced by accelerated particles, which bombard the material to be analysed : X rays (PIXE), g rays (PIGE), scattered particles (RBS), .... Ion Beam Analysis X ray (PIXE) a Elastically scattered particle (RBS) gamma ray (PIGE) Ion Beam Analysis • quantitative • multi-elemental • non-destructive • detection limits down to trace elements Material analysis in archaeometry Motivation • insight into technological skills in the past and sources of supply of raw materials • • • indirect “dating” attributions, authentications (or discovery of forgeries) prerequisite for compatibile and reversibile restoration techniques An essential facility: the external beam set-up 1 cm PIXE analysis of ancient manuscripts (INFN Firenze, Biblioteca Vaticana, Biblioteca Laurenziana) Detecting which pigments were employed provides important art-historical information, both about general trends and specifically about the analysed work. More or less precious materials  symbolic value of the text. Trade routes of raw material import from countries far away. Added or restored parts. External-beam PIXE analysis of the frontispiece of Pl.16,22, from Biblioteca Laurenziana in Florence Discriminating between different pigments with PIXE 1000 Si 800 Lapislazzuli Conteggi 600 400 Al S 200 0 Na K Ca 4000 Azzurrite Cu Conteggi 3000 2000 1000 0 Si Ca Cu Cu Energia (eV) 10000 1000 2000 3000 4000 5000 6000 7000 8000 9000 0 Analysis of documents of historical interest (INFN FI, Bibl.Naz. FI, MPI Berlin) PIXE measurements to quantitatively determine ancient inks composition Important contribution to the chronological reconstruction of Galileo’s hand-written notes about motion Comparison of ink composition in the notes (which are not dated) with that in dated documents (letters, etc.) A letter of Galileo during PIXE analysis with the external beam at the Florence accelerator Some folios from Ms.Gal.72 (Bibl. Naz. Firenze) Discriminating between different inks with PIXE 1400 1200 1000 Fe Ms.Gal.72 f.128 Conteggi 800 600 400 200 Pb Fe Mn 5000 6000 7000 Pb Cu 8000 Zn Pb 9000 10000 11000 12000 13000 14000 0 4000 2500 Fe 2000 Ms.Gal.26 f.29v Conteggi 1500 1000 500 Fe Mn 5000 6000 7000 Cu 8000 Zn Zn 9000 Pb 10000 11000 Pb 12000 13000 14000 0 4000 3000 2500 Fe Ms.Gal.14 f.27r Conteggi 2000 1500 1000 500 0 4000 Fe Mn 5000 6000 7000 Cu 8000 Zn 9000 Zn 10000 Pb 11000 Pb 12000 13000 14000 Energia (eV) Analysis of ceramics Collaboration Louvre – Opificio Pietre Dure – INFN Genova, Firenze, LNS PIXE analysis of the “Ritratto di fanciullo” by Luca Della Robbia – before restoration at the Opificio delle Pietre Dure in Florence Production techniques of the glazed terracottas by the Della Robbia’s Characterisation of the schools of Andrea, Luca, their sons and imitators Changes in the raw materials employed, correlated with time, have been pointed out Analysis of paintings on wood on canvas Understanding the “secrets”of painting techniques of famous artists and/or reconstructing the history of a specific painting (possibility to be a forgery, previous restorations, etc.) PIXE, differential PIXE and PIGE analysis of the Madonna dei Fusi, by Leonardo Universal Leonardo Project, coordinated by OPD Firenze Leonardo Madonna dei fusi ex-Redford version (private collection) Oil painting on wood, 50 x 36 Presumably painted in 1501 The protective varnish layer on paintings two problems 1) discriminating components in the varnish from those in paint and substrate layers; 2) detecting light elements in the underlying layers (X ray absorption) differential PIXE to discriminate the contributions of different layers E1 E2 E3 E1 < E2 < E3 + simultaneous use of PIGE to detect light elements Varnish composition The varnish came out to be essentially but not purely organic. Trace element concentrations have been deduced by PIXE spectra collected at the lowest beam energy, so that protons do not reach the underlying paint and preparation layers. Element Na, Cl, Ca Fe Al, Si, S Mg, P, K Ti, Cu, Ba Zn Concentration ~ 1‰ ~ 0.5‰ 0.5-1‰ 0.2-0.5‰ ~ 0.1‰ 0.1-1‰ Counts/nC 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 Mg Na Al Si S Cl Ar (from air) a) P Ca K Fe 1000 2000 3000 4000 5000 6000 7000 8000 Energy (eV) 0.6 0.5 Fe b) Counts/nC 0.4 0.3 0.2 0.1 Ca Zn Cu The thickness of the varnish layer, as deduced from the comparison of differential PIXE spectra, ranges from ~30 to ~ 50 micron 0.0 2000 4000 6000 8000 10000 12000 14000 16000 Energy (eV) Typical varnish spectra for a) low-Z elements and b) high-Z elements 30 25 a 2.8 MeV a b c d Counts/nC Incarnato 20 15 10 5 0 2000 2.5 Pb Fe Ca 4000 6000 Hg 2.0 b 8000 10000 12000 14000 16000 Energy (eV) 2.3 MeV 1.5 Pb Hg 1.0 0.5 0.0 2000 1.0 0.8 c 4000 6000 8000 10000 12000 14000 16000 Energy (eV) 2 MeV Counts/nC 0.6 0.4 0.2 0.0 2000 0.6 The presence of Hg, which we detected in all the areas of incarnato, can be clearly attributed to the use of cinnabar as red pigment. On the other hand, by comparing spectra at different proton energies, one can see that Pb is present both in the paint layer and in the preparation layer (as lead white). This can be seen from the ratio Hg/Pb peak areas in the different spectra: Hg/Pb Counts/nC Pb Hg a) d 4000 6000 8000 10000 12000 14000 16000 0.10 0.25 0.25 b) c) d) 0.5 Counts/nC Fe Energy (eV) 1.8 MeV 0.4 0.3 0.2 0.1 0.0 2000 In b) and c), Hg/Pb increases with respect to a): the preparation layer is not reached by the proton beam anymore, therefore its contribution to the Pb peak disappears No more Hg and Pb: protons stop in the varnish Ca 4000 6000 8000 10000 12000 14000 16000 Energy (eV) Note that the Ca and Fe peaks are entirely accounted for by their abundance in the varnish. Identification of lapislazuli by PIGE Mountains, pale blue, original Counts/nC 100 80 60 40 4 Pb 3 Counts/nC 441 keV (Na) Pb in the PIXE spectrum mainly derives from lead white mixed in the blue paint 2 1 0 Fe 20 0 2000 Ca 4000 6000 8000 10000 12000 14000 16000 Energy (eV) 340 360 380 400 420 440 460 Energy (keV) 480 500 520 PIXE spectra Gown of the Virgin, dark blue, restored Counts/nC 30 25 20 15 10 5 0 2000 8 PIGE spectra Zn 2.8 MeV 6 Co (cobalt blue) and Zn (zinc white) identify this as a restored part. Pb peaks derive from the preparation substrate (as seen by differential PIXE) Counts/nC Co Fe Ca Pb 4 2 0 4000 6000 8000 10000 12000 14000 16000 Energy (eV) 340 360 380 400 420 440 460 Energy (keV) 480 500 520 Accelerator Mass Spectrometry (AMS) • a very sophisticated technique which detects rare isotopes  extraordinary sensitivity and other  measurement of 10Be, 14C, 26Al, 129I environmental interest radioisotopes of archaeological, geological, 14C dating principle • 14C is a radioactive isotope (T1/2 = 5730 y) • Its decay is compensated by a continuous production in the troposphere due to cosmic rays • An equilibrium concentration of 14C is established (~1.2·10-12) in atmosphere and in all living organisms andamento concentrazione 14C • When an organism dies, its 14C concentration starts to 1,4 decrease with the law of radioactive decay concentrazione (x 10 ) -12 1,2 1 0,8 0,6 0,4 0,2 0 0 10000 20000 time from death 30000 40000 3200 anni 8950 anni [14C]t = [14C]0 e-t/ (con [14C]0 = 1.18 10-12) (with years 50000 How 14C can be measured |dN/dt| = l N b-counting large sample masses (10÷100 g) and long counting times (hours or even days) needed mass spectrometry “standard”mass spectrometry is not sufficiently sensitive Accelerator Mass Spectrometry Measuring 14C with AMS Ultra-high sensitivity (10-15)  dating range up to 50000 years  mass of a sample needed for dating  1 mg 14C measurement with AMS Stripping at HV terminal (eliminates interference of 13CH, 12CH2) Negative ion source (eliminates interference of 14N) Final analysis of high energy ions (removes residual interferences) IBA/AMS accelerator facility in the new INFN Laboratory in Florence IBA beam lines Tandem Accelerator Terminal voltage: 3 MV IBA double-source Multi-sample injector AMS injector High-energy AMS spectrometer IBA beam lines preparing the hall for the new accelerator... external microbeam line beam size at target position  15 m External beam scanning over the sample  Elemental maps by PIXE or RBS Main applications in geology, electronics, biology, but also in art-historical problems: e.g. metal point drawings PAOLO UCCELLO – STUDY OF A KNIGHT Uffizi, Gabinetto Disegni e Stampe – Metal point, lead white prepared paper, earth-green PISANELLO PROFILE OF A WOMAN PARIS, LOUVRE metal point on prepared white paper BENOZZO GOZZOLI COPY FROM THE GROUP OF DIOSCURI DI MONTE CAVALLO LONDON BRITISH MUSEUM Punta metal point + lead white, azure prepared paper LEONARDO DA VINCI STUDY OF A DRAPERY ROMA, ISTITUTO NAZIONALE PER LA GRAFICA metal point, lead white red prepared paper The problem is the non-uniformity of the trace left by the point, in the presence of possibly the same elements in the paper preparation 1 mm Tests on laboratory-prepared samples Bi-dimensional automatic scan (magnetic deflection of the beam over the sample, obtained by magnetic coils) List-mode acquisition (x,y,E) MAP on a surface of  0.40.4 mm2 100 m max Pb stylus Red preparation (S, Hg, Pb, Fe, P, Ca) min The new INFN Laboratory in Florence Also available facilities for: •AMS sample preparation •development and repair of detectors •complementary standard techniques of material analysis The official opening will be next month Collaborations are welcome with other laboratories and archaeologists, art conservators, museum curators etc. thank you!