Zsolt Kasztovszky & Tamás Belgya

Institute of Isotopes

Hungarian Academy of Sciences

and the Ancient Charm Collaboration^*

When investigating a valuable artistic object, the first and foremost requirement is to preserve the intact of the object. Various kinds of physical processes can provide information about the material of the objects, without destruction of them. Neutrons, elemental particles having zero electric charge can enter deep into the irradiated material, and they can undergo different nuclear interactions. Both the neutron capture-based methods (i. e. Neutron Tomography – NT, Neutron Activation Analysis – NAA, Prompt Gamma Activation Analysis – PGAA and Neutron Resonance Capture Analysis – NRCA) and the neutron scattering-based methods (i. e. Time of Flight Neutron Diffraction – TOF-ND and Small Angle Neutron Scattering – SANS) have been previously applied to archaeometry research.

While PGAA with a few cm²-size beam enables us to provide bulk analysis, it is possible to improve the method towards the 3-D elemental mapping through the total dimensions of the objects. If we reduce the beamsize to an approximately 1 mm² cross-section, and detect the emitted gamma photons through a narrow collimator in the same time, we can determine the elemental composition of a smaller volume. Furthermore, with the help of computer work, in principle, we are able to reconstruct the elemental distribution inside the object. This method is called Prompt Gamma Activation Imaging (PGAI).

A new European Commission funded project with ten collaborators, called Ancient Charm, has launched with the aim of combining the above mentioned neutron based methods to achieve 3-D imaging and elemental mapping of museum objects with complex structure. The first experiments to achieve PGAI results will be done at the Institute of Isotopes, on the 5·10⁷ n/cm²·s¹ cold neutron beam of the Budapest Research Reactor. Representative archaeological objects for investigations have been chosen from the collection of the Hungarian National Museum.