Nuclear Physics techniques and methods for Cultural Heritage P.A. Mandò

Bruxelles TechItaly October 4, 2012

Main contributions of Nuclear Physics (principles and technologies) to the diagnostics of Cultural Heritage •dating 14C

(radiocarbon), luminescence techniques

•material analysis Ion Beam Analysis (IBA), X Ray Fluorescence (XRF)

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In Italy.... long tradition of IBA applied to Cultural Heritage problems

in Florence, e.g., we started more than 25 years ago using an old 3 MV Van de Graaff accelerator inherited from previous INFN experiments

we have now a dedicated laboratory, based on state-of-the-art instrumentation, working in close contact with humanists, conservation institutions and other scientists, in Italy and in Europe Laboratoire de Recherche des Musées de France - Louvre Max Planck Institut für WissenschaftsGeschichte Berlin Centro de Micro Análisis de Materiales Madrid Centro Nacional de Acceleradores Sevilla University of Surrey, Guildford International Atomic Energy Agency

Tandetron accelerator, 3 MV max terminal voltage

Ion Beam Analysis (IBA) • Material composition analysis through beam particle bombardment – typically proton or alpha beams at some MeV energy Radiation detection and spectral analysis 1000 Si

Lapislazzuli

Emission of radiation of characteristic energies (X-rays, g, particles…)

Conteggi

800 600

Al

400 S 200

Ca

Na K

0

particle beam

particle accelerator

Object to analyse

Ion Beam Analysis (IBA)

Ion Beam Analysis (IBA) X ray emission (PIXE) a secondary particles emission or inelastic scattering of incident ions elastically scattered particles (PESA)

gamma ray emission (PIGE)

Pros of IBA techniques NON invasive, NON destructive, NO damage

widely multi-elemental (simultaneous detection of almost all elements) very reliable quantitative analysis information (through PESA or differential PIXE) also on layer structure if present, as is often the case

An essential facility to perform IBA especially in the field of Cultural Heritage

The external beam set-up

1 cm 11

At LABEC, two dedicated external beamlines Beam defined by collimation (Ø 0.2 ÷ 1 mm)

Strong focusing system (Ømin 8 – 10 mm)

Using external beam set-ups

we can investigate in a totally non-destructive way

the complete quantitative composition of any kind of artwork

Analysis of stone manufacts,

“Disc with star”, and jewel case, from “Collezione Medicea di Pietre Ornamentali”, Natural History Museum, Florence

...ancient illuminated manuscripts,

External-beam PIXE analysis of the frontispiece of Pl.16,22 (XV century, Biblioteca Laurenziana in Florence)

...historical documents,

Inks in Galileo’s manuscripts (Florence National Library) analysed by external PIXE

...drawings,

PIXE-PIGE analysis of a drawing on prepared paper, by Leonardo or his school

PIXE-PIGE analysis of a drawing on prepared paper, school of Verona, XVI cent.

...paintings on wood or canvas,

Differential PIXE and PIGE analysis of the Madonna dei Fusi by Leonardo

Micro-PIXE and -PIGE analysis of the “Ritratto Trivulzio” by Antonello da Messina

Giorgio Vasari S.Lucia, from Pala Albergotti, Arezzo

Andrea Mantegna Madonna col Bambino, painting on canvas, Accademia Carrara di Bergamo

...glazed terracottas,

External PIXE analysis of the “Ritratto di fanciullo” by Luca Della Robbia – before restoration at the Opificio delle Pietre Dure in Florence

...metal manufacts

PIXE and PESA analysis of some gilded chalices from the Museum of Casa Siviero, Florence

IBA with an external scanning ion microbeam

Ion beam

One can reconstruct elemental maps something similar to what is done with the well known scanning electron microprobe (EMPA), but with two main crucial advantages:

• much better sensitivity (trace elements) • even more important for C.H., the “target” is not in vacuum:  no need of picking up samples from the work

Diagnostics of ink elements distribution in a XVII century document 2 mm

S

max

2 mm

Ca

damage 2 mm precursor?

Fe

Cu

S

Ca

min

Fe

Antonello da Messina Portrait of a man (also known as Ritratto Trivulzio) Torino, Museo Civico di Palazzo Madama Oil painting on wood, 38 x 30 1476

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27

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Ritratto Trivulzio: scanning PIXE measurements Max.

HgM+SK

Immagine ottica

Min.

1 mm

AlK

KK

1 mm

Al and K are correlated with darker areas ( red lacquer) and are on surface; Hg and S (cinnabar) come from below

Mantegna, Madonna col Bambino (1460) Accademia Carrara (Bergamo) 2 mm Au Lα

Pb Lα

Sn K

Fe

2 mm

Au Lα

Si

Al

Pb Lα

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Archaeological dating The 14C method is a great contribution of Nuclear Physics to Archaeology The method is indeed based on a naturally occurring nuclear phenomenon, i.e. the radioactive decay of 14C

Principle of dating through

14C

14C

is present in atmosphere (equilibrium concentration: disappears by radioactive

decay but is continuos produced by cosmic rays) Through various methabolic mechanisms, ALL LIVING ORGANISMS PARTICIPATE IN THIS EQUILIBRIUM and have therefore the same 14C concentration UNTIL LIVING

Principle of dating through photosynthesis

food chain

14C

Principle of dating through

14C

Starting from the death of the organism, the radioactive decay of 14C is no more compensated by any uptake; thus, its concentration decreases continuously

Principle of dating through 14 C-14 R (14concentration C/12C ratio)

1,2

14C

· 10-12 14R(t)

1

= 14R0 · e –t/t

with 14R0 = 1.18 10-12 and t = 8266 y

0,8

t = t · ln [14R0 / 14R(t)]

0,6 0,4 0,2 0 0

10000

20000 time from death

30000 (years)

40000

14C

dating

Also nuclear are the techniques for measuring 14C residual concentrations: the now dominant technology is Accelerator Mass Spectrometry (AMS)

The challenge of AMS Attaining a huge sensitivity still keeping high precision Indeed, ultra-low 14C concentrations (down to 10-15) must be measured with small uncertainty (e.g.: 0.5% error on concentration  40 years on age)

Accelerator Mass Spectrometry can do that .. without destroying significant quantities of the find (few milligrams, or even less, are sufficient)

Measuring 14C with AMS Stripping at HV terminal (eliminates interference of 13CH, 12CH2) Tandem accelerator

Analysis and detection systems

Multi-sample source

Negative ion source (eliminates interference of 14N)

Magnetic + electrostatic analysis + detection systems of high energy ions (remove residual interferences)

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Examples of dating at LABEC

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St. Francis’ relics from Cortona and from the Basilica of Santa Croce in Florence

Archaeological excavations of Etruscan sites River sediments – Abak Creek in Etiopia

Excavations of medieval sites in downtown Florence (Palazzo Vecchio and Biblioteca Magliabechiana)

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Artemidorus papyrus

The frame of a tryptic by Ambrogio Lorenzetti

The Rosano Crucifix

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Exploiting the effect of nuclear explosions in atmosphere during the cold war of Modern Carbon) pMC (percent pMC

200 190

Reference curve for the Boreal Emisphere

180 170 160 150 140 130 120 110 100 90 1940

1950

1960

1970 year AD

1980

1990

2000 45

Many intersting applications in forensics

and biology, but these rapid variations can also be used to discover recent fakes of contemporary art e.g. from the first half of the XX century 46

Samples of fine paper produced in different years 220 Fine paper samples

14C conc. (pMC)

200

Bomb04NH1

180 160 140 120 100 1940

1950

1960

1970

1980

1990

2000

Anno

The date found must be compatible with at least one date prior to production

Canvas samples from dated paintings 217

Tele Bomb04NH1

14C conc. (pMC)

197 177 157 137 117 97 1900

1920

1940

1960

1980

Year reported Annoon the painting

2000

But...if the painting support is only compatible with a later period...

But...if the painting support is only compatible with a later period... A canvas sample from a painting initially attributed to Fernand Legér 200 190

129.05 ± 0.68 pMC

180 170

pMC

160 150 140 130 120 110 100 90 1940

1945

1950

1955

1960

1965

1970

year AD

1975

1980

1985

1990

1995

2000

Not only accelerator-based techniques among nuclear techniques at LABEC Developed an innovative XRF transportable system for certain aspects, approaching the performance of IBA techniques

The new portable XRF spectrometre ● tubes ●

independent PS for the two

He bottle

● acquisition, He flow, x-y translations and camera are remotely Ethernet-controlled by the same computer

Controller Measuring head ● 2 X tubes (30 kV max, 500 mA max) with different anodes (typically Mo and Ti; W if needed) ● interchangeable collimators; typical X ray beam diametre 1 mm ● SDD X ray detector (10 mm2 active area, 450 μmthickness, FWHM 139 eV @ 5.9 keV)

● helium flow in front of both X ray tubes and detector ● 2 lasers for accurate positioning ● viewing camera

Using this portable XRF.... oltremare ultramarine blue layer preparation UltramarineStesura blue layer on aartificiale chalk 6000

Si 5000

conteggi

4000 3000

Al

S (+Mo)

2000

Ca

1000

Na

K

Ca

Fe

0 0

1000

2000

3000

4000

5000 energia (eV)

Mo 22kV

6000

7000

8000

9000

10000

Affresco della Resurrezione Piero della Francesca Sansepolcro, Museo Civico

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Crucifix, Maestro di Figline Santa Croce

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Santa Croce, Cappella Bardi – cycle of frescoes by Giotto

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Madonna del Granduca Raffaello Galleria Palatina

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La Chimera di Arezzo Museo Archeologico Firenze

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Beato Angelico, Crocifissione Capitolare, San Marco, Firenze

Thank you

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