Image copyright Reidar Hahn

US researchers have given details of a plan for one of the biggest physics experiments ever built.

Scientists at Fermilab, just outside Chicago, want to fire a beam of particles called neutrinos through 1,300km (800 miles) of rock some 30km below the surface.

The experiment's aim is to learn more about how the Universe was created.

BBC News has learned that the $1.5bn (£1bn) US project has been invited by the UK to send it a joining proposal.

Those involved describe it as the most important experiment since the search for the Higgs boson.

It is great that British scientists are involved with this big project investigating fundamental questions about the nature of matter David Willetts, UK Science Minister

"It is the next big thing in particle physics," said Prof Stefan Soldner-Rembold of the University of Manchester, who is working at Fermilab.

"It is as big as the search for the Higgs and will revolutionise our understanding of physics."

British component

The director of Fermilab, Nigel Lockyer, told BBC News that the plan to build the Long Baseline Neutrino Experiment (LBNE) was well under way and he was seeking international partners.

"We think that the experiment will cost $1.5bn to build and the US has committed to putting $1bn on the table. So it is a kind of 2/3rds to a 1/3rd arrangement, and so you shop around and see who wants to contribute what."

The UK, through its Science and Technology Facilities Council (STFC), could contribute up to £20m to the project.

The 'ghostly' neutrino particle Image copyright T2K Second most abundant particle in the Universe, after photons of light

Means "small neutral one" in Italian; was first proposed by Wolfgang Pauli in 1930

Uncharged, and created in nuclear reactions and some radioactive decay chains

Shown to have a tiny mass, but hardly interacts with other particles of matter

Comes in three flavours, or types, referred to as muon, tau and electron

These flavours are able to oscillate - flip from one type to another - during flight

Could be a Majorana particle - that is a particle that is equal to its anti-particle

BBC News understands that nine British universities would be involved. These include Manchester, Cambridge, Oxford and University College London.

The head of STFC, John Womersley, described the development as a "win-win situation".

"The UK has shown its interest in the Fermilab initiative. What I hope is that other European participants will get involved. If it can go ahead, it will be an important step for the US and an important step for Europe for a global physics programme."

The UK's role would be to help to build a giant neutrino detector. The detector is likely to be about 12m (39ft) across.

Flavour flip

Neutrinos are ghostly particles that permeate the Universe. They hardly interact with our world, tending to pass right through the Earth.

But 16 years ago, Japanese researchers discovered that these ephemeral flecks did indeed have mass, and not only that - they changed from one form, or flavour, to another as they travelled.

This solved a puzzling observation made by US researchers in a South Dakota mine decades earlier. They found that they were not detecting as many neutrinos coming from the Sun as they were expecting.

The Japanese result suggested that some of them had changed into another type of neutrino on their way to Earth.

This discovery cannot be explained by the current theory of sub-atomic physics. So some physicists believe that by finding out how these neutrinos change flavour and determining their exact mass will give a deeper understanding of how the Universe works and specifically how it came into being.

Matter trick

Current theories of creation suggest that shortly after the Big Bang, there were equal amounts of matter (from which our Universe is made) and anti-matter.

Media playback is unsupported on your device Media caption Pallab Ghosh looks at how the neutrino beam would be fired underground

If that were the case, the two would have cancelled each other out - and yet here we are.

Some believe that contained within the neutrino's oscillation is the cosmic sleight-of-hand - called CP violation in the jargon - that enabled some matter to survive after the Big Bang.

"Neutrinos tell us something about the origins of the Universe," said Prof Soldner-Rembold. "We know there is more matter than anti-matter in the Universe, and that is why we are all here.

"But we don't really understand why, and neutrinos might provide a key to why there is more matter than anti-matter and ultimately why we are here."

It is more likely for neutrinos to change from one type to another if they pass through rock.

So, in order to maximise the chances of seeing this rare event, Fermilab plans to create a beam that will send trillions of neutrinos every second through 1,300km of rock from Illinois to a giant detector in South Dakota.

The beam itself will start 1.5km under the surface, and at its greatest depth will be some 30km down.

The construction of the project is expected to be completed in 10 years' time.

Such experiments do not come cheap, and Fermilab's plan is one of three big experiments that have been proposed to study neutrinos. The others are a European initiative led by Cern, and one suggested by the Japanese.

How many of these experiments can be funded by the international community is unclear, and the three proposals have been involved in a very high-stakes game of poker to determine which experiment will get the nod.

Some argue that the European and Japanese experiments are better in their own way. But there is also an argument that the Americans deserve this one. Europe already has the Large Hadron Collider at Cern, and siting the neutrino lab in the US means it too would have a particle physics flagship.

So, having secured congressional backing for the LBNE project this year, it may be that the Americans now hold the strongest hand, especially with India, Italy and now the UK lining up behind Fermilab.

Britain's Science Minister David Willetts is in Chicago to attend the annual meeting of the American Association for the Advancement of Science. He told the BBC: "It is great that British scientists are involved with this big project investigating fundamental questions about the nature of matter. It will explore the frontiers of science."

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