Page last updated at 09:40 GMT, Friday, 5 December 2008

Collider 'needs warning system'

By Pallab Ghosh
Science correspondent, BBC News


LHC project leader Professor Lyn Evans shows how the super-conducting magnet was damaged

An official investigation into the accident at the Large Hadron Collider has recommended that an early warning system be installed.

This system would detect the early stages of a helium leak, following an incident that has shut down the LHC until June 2009.

The collider is built to smash protons together at huge speeds, recreating conditions moments after the Big Bang.

Scientists hope it will shed light on fundamental questions in physics.

Basically, they have been pulled off their feet and the interconnects have been broken
Lyn Evans, Cern

The report identified the uncontrolled release of one tonne of helium gas as the cause of damage to 53 superconducting magnets.

Better gas pressure release valves could avoid a repeat of the accident on 19 September, it says.

The investigation carried out for the European Organization for Nuclear Research (Cern), confirmed that the cause of the accident was an electrical fault in one of the connectors linking one of the 1200 superconducting magnets that accelerate sub-atomic particles around the LHC.

The fault triggered the release of helium gas within one of the magnets.

Sudden release

It has emerged that valves that should have released the gas pressure couldn't cope with the sudden build up of helium. That led to an uncontrolled release which knocked one of the magnets forward, pushing it on to the magnet in front, dislodging it.

Large hadron collider at Cern

"Basically, they have been pulled off their feet and the interconnects have been broken," said LHC project leader Professor Lyn Evans.

Prof Evans said the incident happened at the very end of the LHC's commissioning process.

"We are extremely disappointed, especially as we had already commissioned seven of the eight sections of the LHC up to full energy," he said.

"This was the last sector to be commissioned and this was really the very last electrical circuit. I must say it felt like a real kick in the teeth."

The report also confirmed the damage would cost £14 million to repair and that experiments will not begin until next summer.

When experiments do eventually begin, they won't be carried out at full power. Instead, the LHC will be operated at two-thirds of its maximum capacity to gently run the machine in.

Formula 1 car

According to Dr Francisco Bertinelli, who is one of the engineers repairing the magnets, "you can think of the LHC as a Formula 1 racing car. It's a complex tool, a complex machine".

He added: "We will not run it from zero to top speed over one afternoon. We will build up our confidence and lower our risks."

Professor Tejinder Verdee of Imperial College London is one of the scientists working at the LHC. He said that the accident had delayed the ground-breaking science that had been planned.

"We would have been analysing collision data today. Now we will do that in the second half of next year," he said.

But he added that great science was still expected to come out of the collider.

"This science has the potential to alter the way we see nature and the way nature operates at a fundamental level so this potential still remains, albeit a few months delayed.

"The great science is still out there ahead of us, which is greatly motivating."

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