Speaker
Dr
Eberhard Lehmann
(PSI)
Description
Neutron imaging techniques can be used quite efficiently for non-invasive investigations in particular when other common methods like X-rays come to the physical limit. This is true with respect to transmission for many metals and with respect to sensitivity for small amounts of organic materials such as moisture, resins, lacquer and corrosion products.
Since the knowledge about the power of neutron imaging is not generally around in the community of museums experts, conservators and archaeologists, it has been necessary to convince them by successful studies of objects with relevance. We got the experience that scientists operating neutron imaging facilities (mainly physicists and engineers) and the community mentioned before have a quite different working style and approach in specific studies. Resulting publications may differ than in many respects when the main authors define the outcome.
Nevertheless, it was possible to perform many interesting studies in collaboration with museums people and archeologists, which give reason to go ahead for similar other such attempts in the future. In this framework, it was also important to get support from funding bodies like National Science Foundation or networks within the European Community (COST, Framework Programs), at least for travelling or even for paying manpower.
From the many different investigations we performed over the years, we want to highlight the following and will give feedback for the particular outcome of the studies:
• The collection of Roman bronze sculptures found in parts of Switzerland
• Bronze statues from the Renaissance period taken from the Rijksmuseum exhibition
• Investigation of the inner content of Tibetan Buddha sculptures
• The structure and the manufacturing process of the Marc Aurelius bust from the Avanches region
The objects are very different in composition, size and content why a specific strategy for the investigations had to be defined in advance to the investigations and for the final analysis. It was important from the beginning to accept that the neutron imaging data can only contribute to the description of the artifacts, their history, manufacturing process and conservation state, but are not a self-standing study alone. The whole pre-knowledge and the expertise of the involved museum experts were needed to complete the picture and the interpretation.
Such studies were always started with simple transmission imaging measurements from several directions to find out if a further tomography run seems to be reasonably – or not. The dimensions of the objects also define the specific beam and detector size, ranging at PSI from 40 cm down to only 3 cm in both directions across the beam. Accordingly, the spatial resolution in the studies can be tuned between 200 and 10 micro-meters.
The data and the derived conclusions are published and available in different format (papers, animated videos via YOUTUBE, books and catalogues).
Primary author
Dr
Eberhard Lehmann
(PSI)
