Non-destructive Ion Beam Analysis for Archeometry and Art
Normally Ion Beam Analysis takes place in vacuum, which limits the size and fragility of objects to be investigated and can also cause more damage because heat is not well conducted in vacuum. Restrictions can be eliminated and damage reduced by performing the measurements in air. This opens up the possibility to apply ion beam analysis (IBA) methods on achaeometric objects and works of arts.
Examples of fields where IBA can be valuable are
Early detection of incipient deterioration or timely diagnosis of potential risks ensures preventive conservation of endangered art objects.
Analysis of the composition of paint from porcelain objects or on enamel by IBA can help art conservators in their job of restoring old and invaluable objects.
- Art technology
Knowledge of the composition of materials used in works of art helps art historians to assign existing works to their creators and improve their understanding of the production methods and materials used for the creation of the artworks.
In favorable cases, simple elemental analysis is sufficient to identify copies or counterfeits. This is especially true for investigations of pigments, which allows to identify contradictions between the period that the object was ascribed to and the period this pigment became available.
- Prehistoric processing and provenancing
The analysis of the composition of glass, metals, pigments used in archeological works of art and in the sources of these materials can provide insights in the way these materials were processed and the trade-routes that existed at the time the artworks were created.
- No sampling
- Non-destructive analysis under atmospheric pressure
- Point analysis (~ 1 mm2), examination of small details or miniatures
- Simple and reproducible positioning, manually or computer controlled
- Short proton exposure times (0.5 - 5 min) with small proton beam currents (< 0.5 nA)
- Sensitive multi-element analysis of main and secondary elements
- Depth-resolved material analysis, i.e. distinction of layer structures
- The (precious) objects have to be brought to the location of the particle accelerator
- No information about chemical bonds
- Presence of organic overlays detectable but not chemically identifiable
External ion beam setup at HZDR
The external ion beam is connected to the 6MV Tandetron of the ion beam center and typically a 4 MeV proton beam is used, which exits the vacuum through a 2 µm Havar foil (cobalt alloy). This beam is very suitable for PIXE and PIGE analysis, which allows multi-element analysis of nearly the whole periodic system. Simultaneous detection of backscattered protons (RBS) highlights C, N, and O in addition to heavy elements on the object surface and provides depth information in the near-surface region. A camera can be used to accurately position the object.
A wide variety of samples can be analysed, such as objects that are too big or fragile to put into vacuum or so precious that damage has to be minimised by using very low beam currents and by cooling with a flow of He-gas or air. Such objects are, for example, porcelain figures, glass or metal objects, paintings.
- Samples can be very large (> 1 m) and have an irregular shape but the area to be investigated has to be put close to the ion beam exit.
- The objects can also be heavy (> 10 kg) but the measurement position has to be stable, sometimes requiring a special support.
- Transport risks, exposure to normal air, costs for packing and assurance etc. have to be considered when selecting objects for analysis. A preselection of objects on-site, e.g. with a handheld XRF analyser, is advisable.
- Study of blue glass from Amarna, Egypt, with respect to the sources of cobalt and other colourants.
Aim: Determine the chemical composition of Late Bronze Age glass objects from the site of Amarna (Egypt) to obtain information about colourants and transition metals associated with the sources of cobalt ore, which is the main colourant for blue glass, a popular colour in pharaonic Egypt. The objective is to obtain new insights into the glass production process in Amarna and to identify the sources of the cobalt ore and thereby determine trade-routes.
Procedure: A set of glass objects from the collection of the Egyptian Museum Berlin (ÄMP) has been analysed with a 4 MeV external proton beam. PIXE with two X-ray detectors and PIGE have been used to determine the main and minor element composition and RBS has been used to study the corosion state of the glass objects that may have been buried for millenia. A partly overlapping set of objects has also been analysed at the New AGLAE accelerator in the Louvre (Paris, France).
The results indicate that the source of the Co-ore used in Amarna were the oases Kharga and Dakhla in the Egyptian western desert.
Anna K. Hodgkinson, Quentin Lemasson, Michael Mäder, Frans Munnik, Laurent Pichon, Stefan Röhrs, Ina Reiche,
A comparative compositional study of Egyptian glass from Amarna with regard to cobalt sources and other colourants
submitted to Archaeometry
- Goethes Prisms
Goethe was a keen scientist who was very interested in colours based on his occupation with painting. In 1810, he published his book "Zur Farbenlehre" (Theory of colours). For this work he did experiments with prisms in collaboration with Johann Wilhelm Ritter.
Objective: determine the composition of the glass prisms, to
- reconstruct experiments, “See what Goethe has seen”,
- understand the production of the prisms,
- evaluate how innovative the prisms are.
First analysis in the museum with a handheld XRF analyser were unsatisfactory.
Procedure: A number of prisms were provided by the Klassik Stiftung Weimar and have been analysed with a 4 MeV external proton beam. PIXE and PIGE spectra were analysed to obtain the composition of the main and minor elements.
For object GFN 0194, no useful results could be obtained with a handheld XRF analyser.
From the PIXE and PIGE analysis, the main elements could be determined as Pb and B and O (from RBS). This points to borate flint glass although Al, commonly found in this type of glass, is missing.
The composition confirms that the prisms are most likely from Goethe's age and the results are useful for the interpretation of Goethe's measurements.
This project was instigated by prof. O. Müller of the Humboldt-Universität zu Berlin, Institut für Philosophie, and supported by the Klassik stiftung Weimar.