Thanks to Michael Murray for the link.

http://www.theaustralian.news.com.au/story/0,25197,24292397-30417,00.html

Large Hadron Collider readies for world's biggest experiment

IT is the most ambitious and expensive civilian science experiment in history, using the biggest machine yet built.
It has sparked alarmist fears that it might create a black hole that will tear the Earth apart, and it has triggered two last-minute legal attempts to stop it.

And next Wednesday, after almost two decades of planning and construction, the project in question will finally get under way.

Beneath the foothills of the Jura mountains, on the border between France and Switzerland, scientists will fire a first beam of particles around a subterranean ring as long as the Circle Line on the London Underground.

This colossal circuit, 27km in circumference, is the world's most powerful atom-smasher, the £3.5 billion ($7.46 billion) Large Hadron Collider, created at CERN, the European particle physics laboratory near Geneva.

Some 10,000 scientists and engineers from 85 countries have been involved. In the years ahead it will recreate the high-energy conditions that existed one trillionth of a second after the Big Bang.

In doing so, it should solve many of the most enduring mysteries of the Universe.

This extraordinary feat of engineering will accelerate two streams of protons to within 0.999999991 per cent of the speed of light, so that they complete 11,125 27km laps in a single second.

The two streams will collide, at four points, with the energy of two aircraft carriers sailing into each other at 11 knots, inside detectors so vast that one is housed in a cavern that could enclose the nave of Westminster Abbey.

The detectors will trace the sub-atomic debris that is thrown off by the collisions, to reveal new particles and effects that may never have existed on Earth before.

The mountains of data produced will shed light on some of the toughest questions in physics.

The origin of mass, the workings of gravity, the existence of extra dimensions and the nature of the 95 per cent of the Universe that cannot be seen will all be examined.

Perhaps the biggest prize of all is the "God particle" - the Higgs boson.

This was first proposed in 1964 by Peter Higgs, of Edinburgh University, as an explanation for why matter has mass, and can thus coalesce to form stars, planets and people.

Previous atom-smashers, however, have failed to find it, but because the LHC is so much more powerful, scientists are confident that it will succeed.

Even a failure, however, would be exciting, because that would pose new questions about the laws of nature.

"What we find honestly depends on what's there," said Brian Cox, of the University of Manchester, an investigator on one of the four detectors, named Atlas.

"I don't believe there's ever been a machine like this, that's guaranteed to deliver. We know it will discover exciting things. We just don't know what they are yet."

The guarantee applies, however, only if the hardware works as it should, and the LHC's first big test comes on Wednesday, when the first beam of particles is injected into the accelerator.

That is a huge technical challenge.

"The beam is 2mm in diameter and has to be threaded into a vacuum pipe the size of a 50p piece around a 27km loop," said Lyn Evans, the LHC's project manager, who will oversee the insertion. "It is not going to be trivial."

Engineers will use magnets to bend the beam around the LHC's eight sectors, until it finally begins to circulate. "That'll be the first sight of relief, that there are no obstacles in the vacuum chamber," Dr Evans said.

"There could be a Kleenex in the chamber - we've had that before. Only when we get the beam around will we be able to tell it's clear."

Once the first beam is in - probably the one running clockwise, though that has yet to be decided - the team will insert the second, anti-clockwise stream of particles.

The first collisions, to test the detectors, should follow by the end of next week.

The next step will be to "capture" the beams so they fire in short pulses, 2800 times a second. These will then be accelerated to an energy of 5 tera-electronvolts (TeV), generating collisions of 10TeV.

The detectors should be calibrated by the end of the year and the collisions will then be ramped up to their maximum energy of 14TeV, generating the conditions that prevailed fractions of a second after the Big Bang.

One of the first scientific discoveries is likely to concern a theory called supersymmetry.

Tejinder Virdee, of Imperial College, London, who leads the Compact Muon Solenoid detector team, said: "What supersymmetry predicts is that, for every particle you have a partner, so it doubles up the spectrum. You have a whole new zoology of particles, if you like."

Theory suggests that if supersymmetry is real, evidence to confirm it should emerge quickly from the LHC, possibly as soon as next year. "If it pops up it'll be quite easy to see," Professor Cox said.

Such a discovery might also help to explain dark matter, which is thought to account for much of the missing mass of the Universe. Only about 4 per cent of matter - galaxies and the like - is visible to our telescopes.

"In this new zoology, the lightest supersymmetric particle is a prime candidate for explaining dark matter," Professor Virdee said.

The search for the Higgs could take longer, though it depends on the particle's mass and thus the energy of the collisions in which it might be found.

If it is at the heavier end of the possible range, the discovery could take as little as 12 months.

A lighter Higgs would take longer to find, as the particles into which it would decay would also be lighter and harder to track.

Other potential discoveries include evidence for the existence of extra dimensions beyond the familiar three of space and one of time, and the creation of miniature (and harmless) black holes, though these are less probable.

"Most of us think we'd be very lucky to find these things," Professor Cox said.

There are two more detectors. The LHCb will investigate why there is any matter in the Universe at all, while Alice aims to study a mixture known as quark-gluon plasma, which last existed in the first millionth of a second after the big bang.