171 Bulletin de l’Association Pro Aventico 57, 2016, p. 171-180 Study of Ancient Metallic Artifacts by Using Neutron Imaging Techniques David Mannes Eberhard H. Lehmann with a contribution of Alex R. Furger Summary T his article describes results of successful inves- tigations of metallic and ceramic ind pieces with archeological and culture historical impor- tance. Since objects of our cultural heritage are often unique and of high value the studies have to be performed completely non-destructively. Although methods with X-rays are very com- mon and available at many places, they often fail when larger amounts of metals are involved. In such cases, neutron imaging methods can be very useful since the penetration of neutrons through (heavy) metals is much higher and clear information about the inner content and struc- ture of inspected objects can be obtained. In the same way, corrosion of metal can be studied very carefully due to the high sensitivity of neutrons for hydrogen, a component in the corrosion products. Also organic remains and agents from conservation treatment can be inspected easily in this manner. Neutron imaging with state-of-the-art perfor- mance and image quality is established at only a few facilities world-wide, given by the limited number of suitable strong neutron sources and the needed experimental infra-structure. The Paul Scherrer Institut operates the Swiss spal- lation neutron source SINQ since 20 years with success and has available dedicated neutron imaging beam lines which are satisfying highest standards and lexibility. We present the physical background of neu- tron imaging, the principle layout of the imag- ing facilities and describe the experimental tech- niques in radiography and tomography modes. Based on this knowledge it becomes possible to describe and to analyze the data obtained by the different examples found in Switzerland in this paper: the golden Marc Aurel bust from Avenches, a sword from the lake of Zug, a gladius from Vindo- nissa, further ind pieces from Avenches (bronze bracelet, sanitary equipment) and ceramic casting remains from Augusta Raurica. Introduction M any objects from our cultural heritage need deeper analysis in order to get knowledge about their provenance, origin, manufacturing process and conservation status. Since the objects should be preserved for future generations, the utilized research methods have to be as non-de- structive and non-invasive as possible. There are many analytical tools available and established in museums and dedicated analysis labs like X-ray luorescence, Raman spectroscopy or even X-ray tomography. Since the discovery of X-rays at the end of the 19 th century cultural heritage objects have been investigated with this penetrating kind of radia- tion where the inner content becomes visible in many cases. This technique has been continu- ously improved by means of higher performance of the X-ray sources with respect to photon energy, source spot size, intensity and the imple- mentation of new detection systems (replace- ment of ilm by digital imaging systems). There is also an access to very intense synchrotron sources enabled in a few cases 1 . However, their beam size is often small and the photon energy too low for the investigation of larger objects (on the order of cm to dm). An alternative and until now not yet very much established technique for non-invasive analysis in the area of cultural heritage research is given with the use of neutrons. Neutron imag- ing works similarly to the more common X-ray imaging (ig. 1), but the source, the beam line layout and the detector for the detection of the radiation are different. Below we will describe the principle differences in the two kinds of imaging techniques caused by the interaction mechanism of the radiation with the sample materials. With 1 Stampanoni et al. 2007.