Characterization of metal threads using differential PIXE analysis

The external differential-PIXE technique is presented in this work as in efficient and non-destructive tool for the characterization of the structure of ancient metal threads. A PEKE analysis for different proton energies has been performed in a selection of gold and silver threads belonging to the Collection of Textiles of La Alhambra (19th century) and to the Medieval Collection of Textiles of the National Archaeological Museum of Spain. The threads are made of metal strips, wound around a silk or cotton core, The use of differential PIXE allows to distinguish strips made of homogeneous alloys from those made of a silver and copper alloy, coated with a thin gold layer. In the same analysis it is also possible to detect the presence or absence of some trace elements of archaeological interest, such as Pb or Hg