2017 Dennis Gabor Medal and Prize

Paul Evans, distinguished professor of applied imaging science at Nottingham Trent University for his pioneering research into material-specific, 3D X-ray imaging and its application in security screening, which has substantially increased the security of the travelling public.

Professor Paul Evans has produced highly innovative research into X-ray imaging, resulting in a number of important cost-effective solutions overcoming major terrorist threats to air travel.

These solutions include the now ubiquitous 3D X-ray imaging systems to identify the shape of objects in baggage and discriminate between metals and low-mass materials. More recent innovations include systems to reduce false alarms and identify highly shape-variant materials, such as narcotics, plastics, liquids and homemade explosives that require material-specific signals.

Evans’s deep insight into the physics of X-ray imaging and his pragmatic understanding of commercial constraints has led to his invention and the commercial exploitation of a number of new X-ray imaging modes.

His early work on multi-beam scanners formed the technological basis for an AIM listed spin-off company, 3D X-Ray Ltd, and the pioneering of a de facto standard for the Advanced Technology class of security X-ray scanner, with an installed global base of around 4,300 machines.

This resulted from his realisation that divergent X-ray beams, from a single source, coupled with folded arrays of dual-energy, material-discriminating detectors will reduce the size and cost of a 3D imaging system. He also invented the castellated dual-energy detector array commercialised by 3D X-ray Ltd and others. This technology enabled a 50% reduction in sensor elements for a given fidelity. Later, the US Department of Homeland Security funded and brokered the exploitation of Evans’ multi-beam scanner with a product launch by the US company Astrophysics Inc in 2012.

More recently, Evans understood that real-time material identification could only be realised with commercial off-the-shelf components by engineering the spatial distribution of coherent X-ray interactions occurring within an inspected object. He conceived the idea that a hollow X-ray beam incident upon a polycrystalline material induces a diffractive lensing to enhance signal-to-noise and provide practical scan speeds.

In recognition of the groundbreaking potential of this approach, the Department of Homeland Security awarded Evans a $4.4 m research contract. The underpinning intellectual property is also the basis for the spinout company HALO X-ray Technologies Ltd.

Evans was awarded the Queen’s Anniversary Prize to Higher Education for world-class research in 2015 and a Times Higher Education Award for outstanding contributions to innovation and technology in 2016.