Camera could enable real-time study of molecular reactions

UK engineers are designing a camera capable of recording X-ray images at rate of 4.5 million frames per second, enabling the true real-time study of molecular reactions.

A team at the Science and Technology Facilities (STFC) has been tasked with delivering the imaging detector for the European X-ray Free-Electron Laser (XFEL).

X-ray imaging has long been used to study molecules, such as the famous diffraction patterns Watson and Crick used to elucidate the double-helical structure of DNA.

The XFEL, however, generates X-ray flashes a billion times brighter than those produced by conventional X-ray sources, opening up new possibilities.

‘If you can imagine taking a diffraction pattern of a DNA molecule, but being able to see how an electron hops from one part of the molecule to another as some change goes on, that’s the sort of thing you’ll be able to do with the XFEL,’ Dr Tim Nicholls of the STFC told The Engineer. ‘But in order to do that, you need these really fast instruments that are capable of capturing that data.’

Now under construction near Hamburg in northern Germany, the XFEL is a two-mile-long facility that will use superconducting technology to accelerate electrons that then generate X-ray flashes, which will last less than 100 million billionths of a second.

The STFC team designed a unique silicon-based X-ray detector, which was then fabricated by IBM — but, as Nicholls explained, there were some significant challenges.

‘Ideally, what you want is it to be sensitive enough to see a single X-ray photon while simultaneously being able to count up to a million photons per pixel. That means it’s got to be very low noise but it’s also got to be able to run very quickly in order to capture an image with every pulse that comes out of the XFEL.’

The detector is being developed in collaboration with Glasgow University and will be delivered to the €1bn (£882m) XFEL facility next year, with experiments hopefully commencing in 2015. By enabling a greater understanding of chemical processes, the XFEL could be used to develop more efficient industrial production processes.