Fast Neutron and Gamma-Ray Interrogation of 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.

Neutron/gamma pulse discrimination analysis of GS10 lithium glass and EJ-204 plastic scintillators

“…Applications in which mixed neutron and gamma-ray radiation fields are involved have gained steady interest through the years, especially in the areas of non-proliferation [1]- [3], radiography and tomography [4]- [8] and medical imaging [9]. Two approaches made it possible for these applications to succeed: scintillation materials sensitive to both radiation fields and multi-detector systems.…”

Simulation study of Fast Neutron Radiography using GEANT4

“…For instance, some of light elements such as H, B, Li, have a neutron attenuation coefficient which is two-three order higher than for element of moderate Z such as Al, Fe, Si. On the other hand X-Rays/Gamma radiation [8] is absorbed to a great extend by heavy elements whereas as it penetrates light material (low z) without significant loss in intensity. Neutrons can also distinguish between different isotopes of the same element.…”

Monte-Carlo simulations of neutron-induced activation in a Fast-Neutron and Gamma-Based Cargo Inspection System

“…In the past several authors presented results of simulations of dose rates and activation of cargo by neutron and gamma based inspection systems (see e.g. simulation of fast-neutron induced activation levels and dose rates in a neutron based detection system for special nuclear matetials in cargo containers [6] or calculation of dose rates of a combined neutron-and gamma-(or x-ray) based air-cargo interrogation system [7]). Of course, these parameters are specific for each method or technique applied and therefore has to be addressed to satisfy the needs for radiation safety and legal issues.…”