Fast neutron and gamma-ray interrogation of air cargo containers

Abstract

There is a worldwide need for improved methods for the scanning of consolidated air cargo for contraband such as illicit drugs and explosives. The strong preference is to directly image the contents of cargo containers without unpacking and with scan times of less than a few minutes per container. In the current paper the various alternative X-ray, gamma-ray and neutron techniques will be discussed and compared. The Commonwealth Science and Industrial Research Organisation (CSIRO) has been working with the Australian Customs Service to develop a scanner capable of directly scanning airfreight containers in 1-2 minutes. The scanner combines fast neutron and gamma-ray radiography (FNGR) to provide high-resolution images that include information on material composition. The composition information greatly facilitates the task of image analysis. A commercial-scale scanner has been installed at an Australian Customs Service facility at Brisbane International Airport to trial the technology and associated business processes. The trial will continue for up to 18 months and includes a comprehensive evaluation by an independent team leader engaged by Customs. The scanner facility incorporates an extensive automated cargo handling system, making possible the continuous processing of large numbers of containers. Results are presented on the image quality of the FNGR scanners, their dynamic range and their ability to discriminate different material compositions. Some results from the FNGR scanner are presented, highlighting the ability of the method to distinguish ill-defined, low-density organic materials that are difficult to detect using conventional X-ray scanners.