Dual Energy material recognition: preliminary results obtained with the radio-tomographic system hosted in Messina

Dual energy technique is a very powerful tool for material recognition. It typically involves X-ray energy below 1 MeV, thus limiting to few mm the thickness of the inspected heavy materials. However, it would be interesting to investigate the chance to extend this technique to higher energies, to allow recognition of thick heavy samples too. Encouraging preliminary tests performed by means of the radio-tomographic system based on a 5 MeV electron linac have suggested to develop a dual energy technique for high energy X-ray beams. This can be done because first experimental tests have confirmed the chance to vary the electron beam energy in a continuous way. As a consequence, bremsstrahlung beams with different end-points can be produced thus allowing to work with different X-ray transmissions. The composition of two different energies X-ray transmission results, allows to perform material recognition. By means of the MCNP4C2 code, simulations have been performed to evaluate the theoretical X-ray transmission in different materials and thickness. These results allow us to choose two X-ray energies providing the best results in order to perform material recognition.