LHC experiment hits major snag with helium leak, two-month delay likely
22 Sep 2008
The Large Hadron Collider (LHC) is beset by problems yet again. After successfully overcoming paranoid efforts to stop the project, the world's largest science experiment at the European Organization for Nuclear Research (CERN) started off to worldwide applause on 10 September 2008. (See: World's largest science experiment begins with the powering on of the LHC)
Soon after the rousing beginning, a transformer failure shut down the cooling plant, which was repaired only last Thursday. Even before the euphoria over the repairs had subsided, that disaster struck. And this time it may be serious enough to throw the entire experiment schedule out of gear.
On Friday, the LHC had its biggest setback till date. This time, the electrical link between two of the particle accelerator's massive 30-ton superconducting magnets has failed, causing a magnet quench event. Due to having to warm up the section of the tunnel containing the magnet in order to conduct repairs, and then cool it back down to its -271°C operating temperature, these repairs will take at least two months.
The exact sequence of events is as follows. Following Thursday's successful repairs, the LHC was cranked up on Friday for a routine test. During this test, one of the bus bar connections that linked cables between the magnets failed, and melted thus causing roughly a ton of liquid helium to leak into one of the tunnel sections. The fire brigade had to be called to handle the situation. CERN said strict safety regulations had ensured there was no risk to people from the malfunction.
"It seems to be a badly made connection - but this all has to be confirmed once we have had the chance to take a look at it," said Dr James Gillies, director of communications at CERN. ''It's too early to say precisely what happened, but it seems to be a faulty electrical connection between two magnets that stopped superconducting, melted and led to a mechanical failure and let the helium out."
These superconducting magnets, by their very nature, require extremely low temperatures to operate. Warming up them to effect the necessary repairs, and then cooling them down again would reportedly take two months. This would put the actual task of colliding opposing proton beams originally scheduled for late October, on a tight schedule as facility shuts down during the winter to save on energy costs. If the problems are not solved till then, the experiment will have to be pushed back to 2009.
"Because the LHC is a superconducting machine that works at very low temperatures, in order to get in and fix it we've got to warm it up, then we go and fix it, and then we cool it down again, and that's a process that's likely to take two months," Gillies said.
However, the concerned scientists are not a worried lot. Considering the huge investments made on the LHC in terms of time and money - 20 years and $8 billion plus - a two-month delay seems but a trifle.
"If you keep an eye on the big picture, we've been building the machine for 20 years. The switch-on was always going to be a long process," said Gillies, who went on to say that "A year or two down the line, this moment will be a distant memory, and we'll be running smoothly."
When the LHC starts up at full speed, it will be able to engineer 600 million collisions every second between protons traveling around its 27-km (17-mile) underground chamber at 99.99 per cent of the speed of light.
