GENEVA -- The world's largest atom smasher which was launched with great fanfare earlier this month 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 (27-kilometer) 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 only 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 (kilometers) 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.
Q & A
Q: What is the Large Hadron Collider?
A: It is the world's most powerful particle accelerator. It is buried inside a 17-mile (27-kilometer) tunnel below the earth. It fires beams of "hadrons" such as protons or neutrons from the nucleus of an atom through two tubes the size of fire hoses. The inside of the tubes are kept in a virtually complete vacuum, at a temperature colder than outer space.
Q: How does the collider work?
A: The LHC fires a beam of protons through the tubes one going clockwise and the other counterclockwise. The beams travel at near the speed of light almost 300,000 kilometers (more than 186,000 miles) per second. That means they zip around the tunnel 11,000 times a second. Supercooled magnets guide the protons until they collide inside massive detectors at four points inside the tunnel.
Q: When did it start operating?
A: The LHC was started up with great fanfare Sept. 10, but it was still in the testing stage and it was to have taken several weeks before scientific experiments with collisions started. Physicists successfully fired hundreds of orbits of beams of protons in both the clockwise and counterclockwise tubes during the next 36 hours.
Q: What went wrong?
A: The temperature in one of the eight sections started rising slightly. Experts determined that a large electrical transformer that handles part of the cooling in that sector had failed and replaced it last weekend. Then they recooled the machine.
Q: Why do they think now the problem is worse?
A: There was still something wrong after the recooling, so experts went down into the tunnel to inspect it. There appears to have been a faulty electrical connection between two magnets that led to a leak of supercooled liquid helium.
Q: Are such failures unusual?
A: No, they can happen in any particle accelerator or collider, and they are expected in the LHC, said to be the most complex machine ever. However, failures can be more difficult to repair in the LHC because it uses such low operating temperatures. That can require a slow, controlled warmup taking several weeks before the repairs can be made.
Q: Who built the collider and how much did it cost?
A: The project was conceived in 1984 by scientists at the European Organization for Nuclear Research, or CERN. The organization's 20 member nations along with observer countries like the United States, Japan, Canada, Russia and India have spent US$10 billion on it.
Q: What do the detectors do?
A: As protons collide, the detectors will search for evidence of extra dimensions to the three of space and one of time that we know of.
They will also look for the "dark matter" believed to make up most of the universe, antimatter that mirrors all known matter, and the Higgs-boson particle, which could explain how all other particles get their mass. All of these have previously only been theorized, but not confirmed.
Q: What about the "Big Bang" part of the experiment?
A: One of the detectors will smash together lead ions to simulate conditions shortly after the Big Bang, which they theorized started the universe 13.7 billion years ago. Scientists hope to learn from this how matter was formed.
Q: Is the experiment safe?
A: Some people have objected to the collider because they fear it could create mini black holes or release massive amounts of energy that would destroy the planet. CERN and leading particle physicists insist there is no danger.