Laboratorio di Tecniche Nucleari per i Beni Culturali - Firenze

The Ion Beam Analysis (IBA) techniques are a powerful tool to investigate in a fully non-invasive way the composition of a material. To this purpose, the object to be analysed is used as a target for a beam of accelerated particles. The interactions of the beam particles with the atoms (or the nuclei) of the target material induce from the latter the emission of secondary radiation (X-rays, gamma rays, particles), having an energy characteristic of the emitting atom or nucleus. Suitable nuclear detectors are then used to collect and discriminate in energy the emitted radiation and make it therefore possible – in a single measurement - to detect and quantify the presence of the different elements in the analysed material.

In general, IBA analysis are:

• Multi-elemental (Nuclear Reaction Analysis excluded)

• Quantitative

• Fast (a single measurements takes few minutes at most)

• Sensitive down to trace level

• Non-destructive: due to the high cross section values (for PIXE in particular), extremely low beam currents can be used, without any risk of damage for the sample

• Information on the stratigraphy can be obtained, by using RBS and differential PIXE, i.e. PIXE measurements performed at different beam energies

External analysis can be performed by extracting the beam into atmosphere after the final collimation through a very thin window, which withstands the pressure difference between the beam line in vacuum and the external environment, while keeping negligible the energy loss of the particles in traversing it. In this way, the object to be analysed can be kept in its "natural" air environment,  thus avoiding the need of picking up of samples and keeping to negligible values the beam-induced heating; in summary, no damage at all is procured to the work.

Among IBA:

• Particle Induced X-ray Emission (PIXE) exploits the X-rays emitted by the atoms

• Particle Induced Gamma-ray Emission (PIGE) exploits the gamma-rays emitted by the target nuclei

• Rutherford Backscattering Spectrometry (RBS) exploits the beam particles, elastically scattered from the target nuclei, whose energy is a function of the mass of the target nuclei and of the depth

• Nuclear Reaction Analysis (NRA)