# Presentation: 478395

## Non-destructive elemental analysis on objects d’art

***Andrea Denker***
***Ionenstrahllabor***
***Hahn-Meitner-Institut Berlin***

- Ion Beam Laboratory ISL

- Art Historical Motivation

- Analysis: PIXE

- Ionenstrahllabor, Hahn-Meitner-Institut Berlin

- Paintings

- Metal Objects

- Conclusions

## Ionenstrahllabor ISL: ion beam laboratory

- 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

## ISL: Accelerators + Target Stations

***14 dedicated***
***target ***
***stations***

## ion solid interaction

- ion beam induced self organisation:
-  lamella structure on NiO/SiO2/Si-Wafer with increasing   fluence (230 MeV Xe):
-  incidence angle 75°,  height ~ 1 μm, width ~ 100 nm(Bolse et al., Appl. Phys. A 77, 11–15 (2003))

## materials modification

**3 μm**

- result:      filter with defined structure,     cylindrical or hour-glass like     pores with huge aspect ratio
- collaboration with industry

*Ion Track Membrane*

*Gore-Membrane*

***irradiation******	******stopping******	******     drying***
***	******etching******	******	******   rinsing***

## 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

**proton**
** ****beam**

**line of****vision**

## Materials Analysis – ERDA: Principle 

- 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

- Materials Analysis – ERDA: Principle

- Elastic Recoil Detection Analysis:

## 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

## art historical motivation: the issues

**provenience**

**age**

**manu-****facturing**

- Ming orforgery?

- decrease of copperin silver coins

- 19th century or older?

- attribution toworkshops

- massive or gilded?

**authenticity**

**conservation/****restoration**

- Archaeology/
- Art History

## motivation: 19th century painting

- Christofano Allori (1615)
- Pitti Palace, Firenze

- many copies of Allori, even by himself
- this copy:unknown artist19th century??
- quality of painting:(brushstroke...)  much older ?

- trust collection, Berlin

## motivation: 19th century or much older?

- stylistic evaluation not sufficient
- looking for more “solid” arguments: chronology of pigments
- collaboration with restorators/art historians

## motivation: info by element identification

**provenience**

**age**

**manu-****facturing**

- Ming orforgery?(colours)

- determination of Cu content

- indirect dating(pigments used)

- attribution toworkshops(metals used)

- techniquemassive or gilded?

**authenticity**

**conservation/****restoration**

- Archaeology/
- Art History

## motivation: analytical techniques

- 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

## PIXE: Proton Induced X-Ray Emission 

- 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

## 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

## depth dependant info:line ratios
radiation from all material, also nuclear reactions   higher background

- radiation from all material, also nuclear reactions   higher background

- High Energy PIXE

- analytical depth _u_p_ to several mm_
- large range of protons

- large cross section for K lines of heavy elements, better separation, less absorption
- small energy loss  non-destructivecross sections constant    over large depth

## high-energy PIXE: analysis up to several mm

- background bearable
- Pb glass  Pb K linesbackground from sample
- 30 μm gold foil _behind_ 3 mm Pb glass	gold signal 	evident

## analysis of art objects: proton beam in air
small straggling: large and bulky objects
HPGe: 180 eV @ 5.9 keV
laser forpositioning
proton intensity:< 0.1 pA
measuring time:~ 200 s
video camerasurveys anddocuments beam spot

- 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

- PIXE : Set-up

## measurements: standards

- 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

## 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

## 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!

## depth depending information

- 12 paint mock-ups using techniques of Italian and Flemish artists, 16./17. century
- analysed using PIXE, estimation of sequence and thickness from K/K, L/K, L/L ratios
- preparation of cross sections and analysed using a microscope

## 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

## Allori copy

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

## Allori copy

- Judith’s cloth, white:
- Pb, traces of Fe  lead white
- no Ti, Zn, Ba  modern pigments can be excluded
- Judith’s cloth, yellow:
- Fe, Pb, traces of Ca
- from Fe K/K: iron on top of lead  most probably yellow ochre on lead white
- no Cd, Cr ...  modern pigments can be excluded
- Holofernes’ face, light brown
- some Fe, Pb  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)

## 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

## 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

## Modigliani Portrait

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

## Modigliani Portrait

- broad palette of pigments:Fe, Zn, Cd, Ba, and Pb in various amountson some spots Cr, Se, Hg
- problem with Ti: Ba L: 4.47 keV Ti K: 4.51 keVBa L: 4.83 keVTi K: 4.93 keV
- Pb in largerdepth

## Prussian Medal

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

## Wiener Pfennig: Hoard of Tulln

- coins extracted
- restoring necessary, chemically cleaned with acids

- 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

## 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)61Zn 61Zn  61Cu  61Ni*:67.4 keV  lineProton Induced-ray Emission

- 2 informations:
-  Cu X-ray: 10 μm
-  Cu  line: 300μm

## Wiener Pfennig, results from Cu K

- 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

## Wiener Pfennig, results from Cu -line

- Wiener Pfennig, results from Cu -line

-  calculation of Cu content using -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

## Medieval brooches

- 630 - 660:	used by noble ladies for coats							iron 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)

## range of 4 MeV protons in plastic: ~ 0.25 mm
use of 68 MeV protons:
energy loss in 1 mm plastic  ( 1 g/cm3): ~ 1 MeV
small lateral straggling

transmission after 1 mm: 		
	 Fe K    6.4 keV   20% Cu K    8.0 keV   46%  Pb L   10.5 keV   69% Ag K   22.0 keV   93%
absorption no principal problem
only qualitative analysis

- use of 68 MeV protons:
- energy loss in 1 mm plastic  ( 1 g/cm3): ~ 1 MeV
- small lateral straggling
- transmission after 1 mm:
- 	 Fe K    6.4 keV   20% Cu K    8.0 keV   46%  Pb L   10.5 keV   69% Ag K   22.0 keV   93%
- absorption no principal problem
- only qualitative analysis

- Medieval brooches

- protons

*X-rays*

## Medieval brooches

- 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

## Egyptian coffin mask

- 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   original gilding
- mask now in the Staatlichen Sammlung ägyptischer Kunst, München

- gilded wood
- queen Satdjehuti 1600 B.C.
- excavated about 100 years ago, private ownership
- status excellent - repaired?
- sensitive object, difficult to position

## Egyptian scarab

- 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

- appeared during World War II is it real?

##  both reports based on art historical expertise
 indirect dating:	identification of pigments 			(Cr in green: after 1850)

-  indirect dating:	identification of pigments 			(Cr in green: after 1850)

- report 1 (Japan):
- 500 years old
- 1 Mio. €

- report 2 (Berlin):
- 100 years old
- max. 25 000 €

**20 cm**

- Chinese bowl: manufacturing date?

## 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
-  report 2 could beconfirmed

## 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

## 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!*

## 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.

- 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.

- The Result of the Evaluation Process

- 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