Atom smasher: 1 bad connection
2008-10-07 14:41
Geneva - A poor soldering job on one of 10 000 connections is the most likely cause of the failure that sidelined the world's largest atom smasher days after the start of the new collider with great fanfare, a senior scientist said on Monday.
"It is very probable that there was a connection that wasn't good," said Lyn Evans, project leader of the new Large Hadron Collider at Cern, the European Nuclear Research Organisation.
Evans said the source problem was small. "It happens quite often in electrical connections," he said, adding that he thought the fault resulted from human error on one electrical connection.
Only one fault in 10 000 isn't bad, "but it cost dearly," Evans said. It halted operations for at least two months, which meant that the collider cannot be restarted until spring, after the obligatory shutdown for the winter because electricity prices are too costly.
Evans says he still hasn't been able to examine the damage because the collider is still too cold to be opened up.
The problem stems from the need to operate the machine near absolute zero to take advantage of the much more efficient use of electricity at "superconducting" temperatures colder than outer space.
The damaged section of the collider 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 rechill it.
'A hard blow'
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.
He said he expected it will then take a maximum of one month - the end of May - to get the machine to high energy.
"It was a hard blow for us," he said. It was the final test of the collider - a large tube running around the circumference of a 27km circular tunnel under the Swiss-French border at Geneva. All the other seven sections of the tunnel had passed the test.
"But that's life," Evans said.
The collider was started before a global audience on September 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.
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.
The collider's use of superconductivity - the ability of some metals to conduct electricity without any resistance near absolute zero degrees - allows for much greater efficiency in operating electromagnets that guide the beams of protons until the particles collide with each other.
The shattering of the protons in the collisions helps scientists to understand better how they are made and how they make up everything and everyone in the universe.
Evans said he looked forward to getting the collider going again.
"It is a jewel, this machine," Evans said.
- AP