# The XTRA Option at the NEUTRA Facility--More Than
## 3 Examples of Applications
### The Sword from Oberwil  
In September 2010 a sword was retrieved near the village of Oberwil from the ground of the lake of Zug. Presumably it has been lying there for more than 450 years. The highly ornamented hit with detailed wood carvings and a multitude of decorative metal inlays indicates that this weapon was already very exclusive at the time it was made and was mainly intended as a showpiece. Nevertheless, signs of wear on the hilt and marks on the blade indicate that it had been in regular use. More detailed information on the history and conservation treatment of the sword can be found in [16; 17]. The aim of the combined neutron/X-ray tomography investigation [18] was to learn more about its making and the condition after the conservation treatment. The X-ray/neutron tomography combination proved especially beneficial due to its complementarity with regards to the metal and organic parts. While X-rays showed high transmission through the wooden parts of the sword hilt, the multitude of small decorative inlays and nails yielded very high contrast. Neutron tomography allowed good penetration of the iron-based blade and showed high contrast for the wooden parts (Figure 5). Information on the wood structure cannot be retrieved from the X-ray data. This is due to the low attenuation of wood and thus the low contrast and the concurrent high attenuation of the very large number of small decorative metal nails and inlays covering the entire hit. From XRF (X-ray fluorescence) analyses, which are reported in [17], it is known that the small metallic inlays consist of tin amalgam. The presence of tin and mercury results in very high X-ray attenuation coefficients for these small decorations, yielding strong artefacts in the reconstructed tomography data set. While it is still possible to obtain information on the distribution of the metallic decorations, it is practically impossible to retrieve details from the wood structure as the reconstruction artefacts from the tin amalgam superimpose this information. The metal of the blade itself, which consists to the greatest part of iron, does not show these difficulties. The result of the neutron tomography proves complementary to these X-ray data. The metallic decorations on the grips are practically invisible, while the wood shows a very high contrast. While it is not possible to obtain much information on the decorations, the structure in the wood can be analyzed. It shows that different wood species were used for the construction. While the visible parts of the grip and the guard are made of box wood (Buxus sempervirens), the small plate used in the pommel as an interlock appears to consist of softwood (cf. Figure 6b). The neutron data also reveals information on the actual mounting of the different parts of the grip; between the tang and grip, thin plates of softwood have been inserted preventing the grip from moving (cf. Figure 6c). It furthermore appears that part of the knots, which are used as decorative elements, are not natural but seem to have been added artificially. This can be seen in the characteristics of the wood structure, i.e., the free ring borders, which naturally converge towards knots containing a nail as a decorative element (cf. Figure 6d). This behavior is not visible for all apparent knots, which implies that some are not naturally grown, but artificially added for symmetry reasons. A comparison of the whole sword, composed of three stacked volumes, is given in Figure 7 in the outer rendering format  
Figure 5: A picture of the sword mounted for the scan of the hilt (**a**). The projections using 150 kV X-rays (**b**) and thermal neutrons (**c**) clearly show the complementarity of the two modalities for this specimen. Figure 6: Virtual slices through the neutron CT data set. The high contrast for hydrogen allows for the inspection of various features: (**a**) Corrosion in the pommel, distinction between soft wood within the pommel and (**b**) hardwood in the grip.