Time of flight X-ray imaging for security applications

Border security is a high priority. The detection of contraband, narcotics, firearms etc. requires improved technical solutions to improve the identification of these materials at entry points and elsewhere. In this proposal we will investigate the use of backscattered x-rays to produce a three dimensional image of the materials inside cargo that is being carried in vehicles or containers. Using a pulsed x-ray source the time of flight of the backscattered x-rays will be measured with an array of scintillation detectors in order to obtain data that can be used to create a three dimensional image. Preliminary experiments at the VELA facility at Daresbury using a single detector have shown a relationship between the time of flight and the position and composition of an object. As the time of flight is a few nanoseconds it is necessary to develop a fast digital data acquisition system for the detector array. This data acquisition development and the use of the system in two sets of experiments are the focus of this proposal. The array of up to eight scintillation detectors and the data acquisition system will be used at the VELA facility at Daresbury to collect data that will be later analysed to show its potential for producing three dimensional images. The system will then be used a Rapiscan's facility at Stoke where the pulsed x-ray beam is more like those that could be widely deployed. These experiments will investigate improving the response of the system and the algorithms developed in the first part of the work.

The aim is to produce an improved detection system for Border security and similar applications. Rapiscan are a world leader in this field and know the technological developments that are needed. If successful the main impact of this work will be to give Rapiscan and the security industry the confidence to develop full scale systems at a much reduced risk level. Three dimensional imaging will give much improved information on the contents of the item under inspection potentially much more quickly as this will eliminate the need for multiple scans. The provision of security systems is a large international business. Rapiscan estimate that a three dimensional imaging system would have an initial market of 10 systems per year each of value $1 miilion.