Simultaneous Real-Time Fast-Neutron/γ-Ray Tomography and Radiography

Neutron radiography is a non-destructive approach that has evolved in the last decades in contrast to the use of imaging facilities located in proximity of nuclear reactors and spallation sources. The majority of prior techniques exploit thermal neutrons by virtue of their relatively easy detectability, with there being less focus on fast-neutron imaging. In this research, we exploit fast neutrons emitted by a low-dose and mobile californium-252 source to perform fast neutron radiography. Simultaneously with neutrons, γ rays are also emitted by this particular isotope from spontaneous fission. The detector system used in our work affords the detection, real-time, of both fast neutrons and γ rays by means of pulse gradient analysis performed by a mixed field analyser. This retains event histories of both types of radiation, thus making possible to undertake, at the same time, neutron-, γ- and combined n-γ- radiography with the same field of view. The novelty of this technique is the use of a single radiation source and detection system that yields to two different radiographs of same object. In this particular record, we apply this technique to image a laptop battery, with the aim to highlight the presence of lithium ion polymer inside the battery's cells. Our study shows how combined n-γ imaging is a valid alternative to X-rays imaging when there is the need to depict low-atomic number elements, as well as to discern elements with similar density. The system presented in this study is potentially applicable in safety & security inspection; for instance, it has the potential to be coupled with the advanced cabin baggage screening systems in airports, improving their detection performance.