PIXE / PIGE

PIXE / PIGE External beam - the proton beam on air

Material analysis of unique objects without sample preparation

• non-destructive analysis
• simple object positioning on air
• short measuring times
• multi-element detection
• main and secondary components
• depth resolved results available
• chemical bonds not detectable
• no analysis of organic materials

The focused beam of accelerated protons leaves the vacuum tube through an exit pipe and strikes the object which is positioned in front of it under atmospheric pressure. Proton induced Coulomb interactions and nuclear reactions take place with atoms of the analytical substance. Hence, the atoms emit X- and Gammaradiation (PIXE, PIGE) the energy of which is characteristic for the individual chemical element. The arrangement of different detectors allows multielement analysis within nearly the whole periodic system. Simultaneous detection of backscattered protons (RBS) provides depth information in the near-surface region of the irradiated position.

Metals

The gold composition was measured for each detail on the “Sky disk of Nebra” in order to clarify whether it belongs to the original version or possibly to a later additive.

Glass and Ceramics

As shown for a Tiffany glass, the iridescent effect is due to light interference from a thin surface layer of tin oxide. Glass surface corrosion of Barock glass is indicated by the enrichment of oxygen at the surface. Full quantitative composition analysis is available.

Paintings

Identification of paint layers is possible by variation of the proton energy, for example: Lead white priming under the red robe (cinnabar, HgS) is indicated by an increased Pb signal at a higher proton energy, i.e. increased depth of analysis. A mini beam of 0.3 mm diameter allows to study narrow details, e.g. fine lines of delicate hand drawings.