Time of flight X-ray imaging for security applications

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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.