Detecting Bombs in Air Cargo

Dr Yi Liu described the CSIRO Air Cargo Scanner and its Development and Commercialization at ANU today. Surprisingly this is developed by a group of researchers who previously worked on analysing minerals in mines and processing plants. This used neutrons, X-rays and other techniques to discover the chemical composition and shape of minerals at a distance. This experience was applied to detecting bombs and illicit materials in air cargo. This is more difficult than for normal airport luggage, as the cargo containers are much larger and can have a clutter of different materials. The work started in 2002 and prototype was produced in 2005, with the produce now commercialised by Nuctech.

Neutrons can be used to detect the composition of material , but not density or precise shape (20mm x 20mm resolution). X-rays can be used for density and more precise shapes (5 mm x 5 mm) but not composition. A combination of scanning techniques are therefore used to identify both the shape and composition of materials.

The Mark II scanner is at Brisbane Airport. The device has a concrete shield for safety. Cargo containers travel trough the scanner on a conveyor. The system produces a combined false colour image. In a demonstration image the rubber of a motorcycle seat shows as red and the oil in the sump as green, while the metal is black. The operator sits an a normal office desk and views the images on a computer LCD display. The unit is not intended for people or animals, but even so the radiation is at a safe level.

The commercial version from Nuctech works essentially the same as the prototype, but has improvements with a quasi-3D display, dual energy X-ray system and a water radiation shield. The unit has 960 fixed neutron detectors (levels are too low to use a moving detector). The ray system has two detectors at 9 degrees for each x-ray source to provide some three dimensional information.

Future work is on automatic highlighting of suspicious objects in the container, use for sea and land containers and better neutron sources and detectors.

One suggestion I made at the seminar was automatic matching of the manifest to the material detected. Modern manifests are in machine readable format, so the computer system could work out what proportion of materials should be in the container and compare this to what is detected by the scan. The computer system could also look for suspicious similarities between different containers, even those entering at different ports. Also air containers have transparent sides. An optical scanner could also be used (perhaps using infrared). A high resolution optical scanner could be used to recognise any writing on the contents and use this in automated or manual analysis. Analysis could include use of open source analysis, such as information from the web.