PIXE and RES as a tool for the analysis of historic copper halfpennies

RES and PIXE microbeam analysis is used to investigate the trace element co ncentrations as well as the surface corrosion of counterfeited copper halfp ennies from the mid 18th century. PIXE elemental mapping was used to identi fy regions with a minimum of light element contamination which could be use d for accurate trace element determinations. RES analysis of selected point s on the map could be used to confirm the absence of corrosion or contamina tion, and in addition yielded valuable information on the composition and s tructure of the corrosion layers. (C) 1999 Elsevier Science B.V. All rights reserved.