CERN: Damage to new particle accelerator forces two-month halt

Sunday, September 21, 2008

GENEVA -- The world's largest atom smasher has been damaged twice and will be out of commission for at least two months, its operators said Saturday.

CERN, the European Organization for Nuclear Research, said Saturday that a large amount of helium had leaked into the 17-mile circular tunnel deep under the Swiss-French border that houses the Large Hadron Collider.

The massive collider began operating Sept. 10 to the delight of physicists around the world, flinging protons around the circle at nearly the speed of light. But it had to be shut down 36 hours later due to a failure of an electrical transformer.

That was repaired, but a CERN statement said a second failure took place midday Friday in the last section of the tunnel to undergo testing at high current, causing the large helium leak.

CERN spokesman James Gillies said the latest incident was several miles from the earlier damage. It is considered much more time-consuming to repair than the first malfunction.

"Preliminary investigations indicate that the most likely cause of the (Friday) problem was a faulty electrical connection between two magnets, which probably melted at high current leading to mechanical failure," said the statement Saturday.

It said the sector will have to be warmed up for repairs to take place, which will require a minimum of two months down time for the collider.

Such faults are common in colliders designed for use at room temperature, and the repair time would be a matter of days, Gillies said. What will slow it down for the LHC is the time it will take to warm up the section and then cool it down again.

The Large Hadron Collider operates at near absolute zero, colder than outer space, for maximum efficiency.

Gillies said it would take "several weeks minimum" to warm up the sector.

"Then we can fix it," Gillies said. "Then we cool it down again."

The $10 billion particle collider, in the design and construction stages for more than two decades, is the world's largest atom smasher. It fires beams of protons from the nuclei of atoms around the tunnels at nearly the speed of light.

It then causes the protons to collide, revealing how the tiniest particles were first created after the "big bang," which many theorize was the massive explosion that formed the stars, planets and everything.

CERN announced Thursday that it had shut down the collider a week ago after a successful startup that had beams of protons circling in both clockwise and counterclockwise directions in the collider.

That shutdown was caused by the failure of an electrical transformer which handles part of the cooling, CERN said. That transformer was replaced this week and the machine was lowered back to operating temperature to prepare for a resumption of operations.

The CERN experiments with the particle collider hope to reveal more about "dark matter," antimatter and possibly hidden dimensions of space and time. They could also find evidence of a hypothetical particle -- the Higgs boson -- which is sometimes called the "God particle" because it is believed to give mass to all other particles, and thus to matter that makes up the universe.

Smaller colliders have been used for decades to study the makeup of the atom. Scientists once thought protons and neutrons were the smallest components of an atom's nucleus, but experiments have shown that protons and neutrons are made of quarks and gluons and that there are other forces and particles.

The LHC provides much greater power than earlier colliders.

Its start came over the objections of some who feared the collision of protons could eventually imperil the Earth by creating micro black holes -- subatomic versions of collapsed stars whose gravity is so strong they can suck in planets and other stars.

CERN and leading physicists maintain the project is safe.

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