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Sunday, September 21, 2008

Problems Stall Action for Collider

A week after subatomic particles began zooming around its underground racetrack to cheers and Champagne toasts, the world’s most powerful particle accelerator, the Large Hadron Collider, at CERN outside Geneva, is still struggling to take its next big step.

The scientists and engineers on the project had hoped that as early as late next week the collider would actually begin to collide subatomic particles, though at energies far below the cataclysmic levels that have had some skeptics worried about the creation of black holes that could eat the world, a possibility that scientists dismiss as science fiction.

The machine is designed to accelerate protons to seven trillion electron volts and then bang them together in search of new forces and particles. The initial attempt at running protons through the collider, on Sept. 10, was so successful that CERN scientists thought they might achieve the initial collisions ahead of the scheduled two weeks after “first beam.” But those hopes were dashed by a series of “teething problems,” as one engineer put it, including the failure of a 30-ton transformer in the system for chilling the helium that, in turn, chills the superconducting magnets that guide the protons. On Friday, CERN announced that a large spill of helium in the collider tunnel would mean a further delay.

The collisions, when they happen, will be at the relatively modest energy of 450 billion electron volts, a realm well explored by other machines, and will last for only a day or two.

They will allow the scientists to calibrate and begin to understand the mountains of detectors, wires, computers and magnets that have been built to capture and analyze the proton collisions. “The first job is to relearn what we already know,” said Tom LeCompte, from the Argonne National Laboratory in Illinois. He works on a collider detector known as Atlas.

When the machine will begin colliding protons at high energy is a guessing game at best. If all goes well, scientists and engineers at CERN say, it could happen by the middle of October.

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