A bad electrical connection likely caused the malfunction that sidelined the world's largest atom smasher days after it was launched with great fanfare, a senior scientist said Monday.
The fault was probably a poor soldering job on one of the particle collider's 10,000 connections, said Lyn Evans, project leader of the Large Hadron Collider at CERN, the European Nuclear Research Organization.
Only one fault in 10,000 isn't bad, “but it cost dearly,” Evans said. It will take at least two months for the repair, meaning the collider cannot be restarted until spring, after its mandatory shutdown due to high electricity costs during the winter.
Evans said he still hasn't been able to examine the damage because the collider is too cold to be opened. The machine operates at extremely cold temperatures to take advantage of superconductivity – the ability of some metals to conduct electricity without any resistance near absolute zero.
It has to be warmed gradually to room temperature over five weeks so that humans can work inside and make repairs, Evans said. Then it will take another five weeks to re-chill it.
The collider was started before a global audience on Sept. 10, with beams of protons being fired at nearly the speed of light around the collider, first in one direction and then in the other. The electrical fault occurred nine days later.
Before the failure, the plan had been to step up power on the collider so that scientists could start with test collisions of subatomic particles before the winter shutdown. That will have to wait until next April, Evans said.
The failure occurred during the final test of the collider – a large tube running around a 17-mile circular tunnel under the Swiss-French border at Geneva.
CERN specialists have already figured out that a connector between electromagnets failed and heated up, causing a magnet “quench,” or shutdown. It apparently melted a hole in the tube, causing a leak that spilled about a ton of the liquid helium used to chill that section.