Neutron diffraction analysis of 'black boxes'

The Ancient Charm project addresses several aspects of neutron analyses of archaeological materials, with the specific aim to developing neutron activation and neutron diffraction into imaging methods. One of the central techniques is element determination by Neutron Resonant Capture Analysis (NRCA), besides the more established Prompt Gamma Activation Analysis (PGAA). Neutron diffraction is another technique employed in this project, for mapping the spatial distribution of crystallographic phases in a sample. Ancient Charm provides the prospect of combining several of these analytical neutron methods with neutron radiography in order to obtain a comprehensive characterisation of the interior of an artefact. This paper reports on neutron diffraction results on 17 of so-called 'Black Boxes', closed cubes containing geometrical arrangements of materials such as metals, minerals, ceramics, and organic matter. The measurements were carried out at the pulse neutron source ISIS at the Rutherford Appleton Laboratory in the United Kingdom. The aim of this 'Black Box' study was to identify strengths and weaknesses of neutron diffraction for analysing archaeological objects and to develop a best practice for a combined use of analysis methods for different combinations of materials.