Neutron Imaging Studies within the "neu_ART" Cultural Heritage Project

The potential of imaging by thermal and fast neutrons has been assessed in the Cultural Heritage field, given the fact that this technique is non-invasive and neutrons can penetrate many layers of thick objects. This method provides valuable information to assist preservation and restoration activities and to help dating or attributing through the understanding of the manufacturing techniques. An investigation of the imaging capabilities of the Italian Neutron Experimental Station INES (at the ISIS pulsed neutron source of RAL laboratories, UK) and the Neutron Computerized Tomography and Radiography laboratory (NECTAR at the FRM II reactor in Munich) applied to artwork objects made of metal alloys was carried out. For this purpose custom samples have been prepared, following size and composition of typical ancient works of art. Through neutron tomography the internal structure of the testing metal objects was reconstructed and millimetric scale details inside them were resolved. Moreover, several measurements have been performed to fully characterize the performance of both apparatus. Their imaging response has been analyzed in terms of linearity, signal to noise ratio, dynamic range and resolution by the usage of scintillator screens of different chemical composition and thickness. A detailed description of these studies is presented.