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Wednesday, 6 November, 2002, 12:29 GMT
Making 'ghosts' in a machine
Isis, BBC
Isis, the world's most powerful neutron machine

In a quiet corner of Oxfordshire, particle physicists are dreaming of solving the mysteries of the Universe.

At the heart of the matter is something once described as the tiniest quantity of reality ever imagined by a human being.

The ghostly particles, neutrinos, weigh almost nothing, but they could help explain why the Universe, and everything in it, exists.

We could make it into a tourist site. It's an encouragement for children to study science

Prof Ken Peach
If the hopes of scientists are realised, the UK will become home to a neutrino factory.

In such a machine, muons, the more exotic and heavier brothers of electrons, would be sent racing around a kilometre-long underground ring.

As the muons decayed, intense beams of neutrinos with a known composition would be created and then directed at detection equipment thousands of kilometres away through the Earth, where the particles' composition would be different.

The precise details of this difference are a very sensitive probe of the laws of nature.

High-energy frontier

The Rutherford Appleton Laboratory near Didcot is a potential site for the neutrino factory, as the world's physics community looks to the future.

A new particle accelerator, the large Hadron Collider, or LHC, is already being built at Cern, the European Laboratory for Particle Physics in Geneva, to explore what is known as the high-energy frontier.

Sudbury Neutrino Observatory in Canada: It detects neutrinos from the Sun
It is due to be switched on in 2007.

However, scientists are already discussing the other facilities that will be needed to complete the search for the new physics that must exist beyond the current Standard Model of particles and their interactions.

A neutrino factory is one of the key facilities needed for this task.

One argument for building the neutrino factory at the Rutherford Appleton Laboratory is that much of the infrastructure is already in place.

It is home to the world's most powerful machine for producing neutrons and muons. Scientists from all over the globe come to the facility, known as Isis, to probe the structure and dynamics of matter.

Dr Andrew Taylor, the Director of Isis, says it achieved its world leading position by building upon the achievements of the accelerators developed for particle physics in the 1970s.

"What we are now seeing is a neutrino factory that will build upon our development since then of high power proton accelerators and target technology," he explains.

"In a very real sense, we are returning the favour."

Nobel Prize

A neutrino factory would be used to find out more about the fundamental properties of neutrinos, their recently discovered mass and the phenomenon of neutrino oscillations, recently acknowledged by the award of the Nobel Prize in Physics to Ray Davis and Masatoshi Koshiba.

These experiments might also shed light on the missing anti-matter of the Universe. At the time of the Big Bang, matter and anti-matter are thought to be have been generated in equal quantities and, according to theory, they should have annihilated each other in a flash of energy.

Standard Model
The current theory of fundamental particles and how they interact
The triumph of particle physics of the 1970's
One part of the Standard Model is not yet well established
We do not know what causes the fundamental particles to have masses
How normal matter has come to dominate the Universe around us is therefore a puzzle.

A neutrino factory could give a tantalising glimpse of the tiny asymmetry in the properties of matter and anti-matter, and help to explain where all the missing antimatter went.

It is possible that the oscillations might be subtly different for neutrinos and anti-neutrinos. Even a small difference could have a very large cosmological impact because of the enormous number of neutrinos still around as relics of the Big Bang.

"We started thinking seriously about neutrino factories three or four years ago," says Professor Ken Peach, director of particle physics.

"Because of all the technology we have at Isis in the Rutherford Lab, it seemed to us a natural thing to look at. We have all the elements to make major contributions to the design and construction of such a machine."

First steps

The idea of the neutrino factory is still very much a dream. It would be a multi-million-dollar venture and would take at least 10 years to build.

The crucial first milestone is to modify Isis for what is known as the muon ionisation cooling experiment (Mice).

Koshiba, AP
Masatoshi Koshiba (l) inside Japan's Super-K Neutrino Observatory won this year's physics Nobel
It is seen as an essential step in being able to show to the world that the UK knows how to design and build a neutrino factory.

Dr Bill Murray, a particle physicist at the Rutherford Laboratory, explains: "Mice is a technology demonstrator, to show that we can prepare muons for acceleration in the 2 millionths of a second before they decay."

An international collaboration of scientists from Europe, North America and Asia is working on a proposal for the Mice experiment, to be ready in December.

But the UK will face competition from a dozen or so other likely sites around the world wanting to host the project.

Particle joke

"Anybody who puts down a list of where a neutrino factory can be built has to put Rutherford on," says Professor Peach. "If we can pull off this feat of getting Mice, this puts us in a very strong position."

Professor Peach says his main motivation is the quest to understand the Universe. But he sees other benefits to locating the neutrino factory in Oxfordshire.

"We could make it into a tourist site," he says. "Cern has 40,000 tourists a year. It's an encouragement for children to study science."

Professor Peach likes to tell a story about describing his job to a stranger on a train.

Following the ideas of the famous physicist Richard Feynman, he tells the stranger that he knows the secret equation that describes the Universe - it is simply "U=0", where U stands for the Universe. The only question that we have to answer is "what is U?"

Building a neutrino factory offers a chance beyond the mighty atom smasher of Cern to fill in some more of the missing gaps in our understanding of the way in which the Universe works at its most fundamental level.

See also:

08 Oct 02 | Science/Nature
30 Oct 02 | Science/Nature
18 Sep 02 | Science/Nature
22 Apr 02 | Science/Nature
14 Mar 00 | Science/Nature
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