Neutron Activation Autoradiography

Abstract

Autoradiography uses a photographic film or imaging plate which are placed in direct contact with a painting after irradiation by slow neutrons. The pigments become radioactive after the interaction with the neutron beam and the emitted radiation (gammas, X-rays and electrons, so called beta-rays) is registered in the film or plate. The blackening of the film is mainly due to the beta-rays because the gamma rays are high energetic and hardly interact with the film. In this way the obtained picture can be called beta-radiography, but since the radioactive elements in the painting itself are the source of beta rays, the technique is called “autoradiography.” In addition gamma spectrometry can be applied for detecting the emitted radiation from activated elements and by analysis of the position of the energy peaks and their intensity information about the chemical composition and the amount of the pigments can be obtained. In this way position sensitive elemental analysis is possible.