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Magnet Trouble Likely to Complicate Start of Large Hadron Collider

Repairs may preclude a test run before the particle smasher starts tackling the Higgs boson
magnet



© CERN

Researchers building the world's next top particle accelerator, the Large Hadron Collider (LHC) that straddles the Franco-Swiss border, may not get a chance to work out the bugs before they fire up the machine in earnest.

The experiment is still on track to begin hunting for the long sought Higgs boson next March, says LHC project leader Lyn Evans of the European Organization for Nuclear Research (CERN). But a crucial upgrade of 16 superconducting magnets around the accelerator will likely prevent a full test run planned for this December, he says, meaning researchers will have to troubleshoot glitches on the fly. Under that scenario, "if we have any problems, we will have to stop and fix them," he says.

Annoying? Most likely, especially given the potential competition in the quest for the elusive Higgs.

One of the 16 LHC magnets failed a high-pressure test with a bang earlier this month, leaving engineers at CERN and Fermi National Accelerator Laboratory (Fermilab)—the Batavia, Ill., lab that built the magnets—scrambling to plan a fix.

This week, after evaluating two Fermilab proposals, CERN opted for welding on pistonlike, aluminum-jacketed rods composed of a stiff metal alloy to secure each eight-ton magnet in its housing, says Fermilab spokesperson Judy Jackson.

Evans says CERN will know for sure in a few weeks whether it will have to curtail the LHC test run, after engineers build prototypes of the upgraded magnets. The repair job is relatively simple but has to be squeezed into the lab's tight schedule, he says.

To retrofit the magnets, engineers will have to warm one or two of the accelerator's eight segments from its current 1.9 kelvins, install the rods and then cool the segments down again. Each warm-up or cooldown can take weeks.

Making up that lost time "looks very hard," Evans says. "Maybe it'll be faster than we think, but I'd be surprised."

Before the magnet failure, the LHC was already five weeks behind schedule, raising the specter that the world's soon-to-be second biggest particle smasher, Fermilab's Tevatron, might beat it to the finish line.

The Tevatron has the potential to detect the Higgs, says particle physicist Gerald Blazey of Northern Illinois University in Dekalb, a member of the Tevatron's DZero Experiment, which looks for signs of the Higgs in the collisions of protons and antiprotons.

Blazey says that a thorough search would require the machine to run through 2009, well after the LHC is slated to start up—beset by glitches or not. "I would never say that the Tevatron is [definitely] going to discover the Higgs before the LHC." But it's possible.

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