Special Reports

A super-powered neutrino generator could in theory be used to instantly destroy nuclear weapons anywhere on the planet, according to a team of Japanese scientists.

If it was ever built, a state could use the device to obliterate the nuclear arsenal of its enemy by firing a beam of neutrinos straight through the Earth. But the generator would need to be more than a hundred times more powerful than any existing particle accelerator and over 1000 kilometres wide.

"It is really quite futuristic," Alfons Weber, a neutrino scientist at Oxford University, UK, told New Scientist. "But the maths and physics seems to be right."

John Cobb, another researcher at Oxford University, cautions: "It might be technically feasible, given massive investment, but there are still unsolved problems."

Ghostly particles

Neutrinos are elementary particles with no electric charge and virtually no mass. They are produced in the nuclear reactions within stars and pass through the Earth in their thousands every day. As they pass through ordinary matter, neutrinos scatter atomic nuclei.

By scattering neutrons in uranium or plutonium, a sufficiently high-powered beam of neutrinos would destabilise a nuclear bomb. According to Hiroyuki Hagura and Toshiya Sanami at Japan's KEK High Energy Accelerator Research Organization and Hirotaka Sugawara at the University of Hawaii this would cause the weapon to "melt down" without triggering the chain reaction needed for it to fully detonate.

But the "muon storage ring" generator needed to propose the neutrino beam would need to be 1000 kilometres wide. It would also require 50 gigaWatts of power to operate - the same as used by the entire UK - and would cost an estimated $100 billion to construct.

Weber says the first stage of a generator might be feasible within 10 to 20 years, but he reckons the main problem is that the neutrino beam produced would be just a few metres wide. This means a target would need to be very precisely located beforehand. He adds that the beam would produce dangerous alpha and neutron radiation in any living thing in its path.