Neutron detector can identify presence of nuclear weapons

Scientists at Oxford University and Imperial College London have designed a low-cost, highly sensitive neutron detector that can identify the presence of nuclear weapons.

Neutron detectors are used at border crossings and shipping ports to identify lorries and shipping containers concealing hazardous nuclear materials such as plutonium, a neutron-emitting substance that is used to make nuclear weapons.

Project leader Dr Jon Carr of Isis Innovation told The Engineer: ‘Obviously what you want is something that reacts to a neutron passing through it. You need the products of that reaction to then be picked up and then you have to pass that signal to an actual detector.’

Neutron detectors contain flourescent tubes where reactions take place. The material that reacts with the neutrons inside these fluorescent tubes is known as the scintillator. Previous neutron detectors have used Helium-3 as the scintillator, but this element is no longer as abundant as it once was.

‘Ten years ago, Helium-3 was a very common material because it was sourced from US military nuclear projects,’ said Carr. ‘But now these projects have finished, there isn’t a stock building up anymore.

‘In addition, Helium-3 has medical and science applications, which meant the price of the element went 10-fold within a couple of years,’ he added.

Carr said that current neutron detectors using Helium-3 cost around $80,000 (£50,500), but he was unable to elaborate on exactly how much the new detector would cost.

The new detector, which is being commercialised by Isis Innovation, relies on the more abundant and significantly cheaper Lithium-6. This alternative scintillator actively discriminates against gamma rays and as a result there are fewer false alarms. ‘This is because there are lots of natural gamma sources that can set the alarms off, including ceramics and bananas,’ said Carr.

The technology is now the subject of a patent application and Isis Innovation would like to discuss licensing the technology with interested companies.

The team has received £70,000 from the University Challenge Seed Fund to develop a prototype device by the end of June 2012.