Evaluation of a computer aided neutron tomographic system incorporating a gaseous position sensitive detector

A position sensitive gaseous detector, formerly designed to operate with X-rays, has been modified to equip a third generation tomographic system working with a parallel thermal neutron beam. For this purpose, the original filling-gas has been replaced by 3He-enriched helium, which plays simultaneously the role of filling-gas for the ionization process and converter of neutrons into charged particles. This paper describes the modifications done to the detector, the measurements carried out to evaluate its own performance and that of the tomographic system attached to it. Some tomographic images acquired using that system are presented as well. Tomographic systems equipped with this kind of detector should require substantially much less time than those conventional ones, where a sample translation is required. The Argonauta reactor operating at the Instituto de Engenharia Nuclear (IEN/CNEN-Brazil) has been utilized as the source of neutrons, furnishing a flux of 4.5×105 n cm−2 s−1 at its main irradiation channel where the tomographic system has been placed.