Date set for restart of Large Hadron Collider
The Large Hadron Collider will be turned on again at the beginning of April, according to Cern director general Robert Aymar.
The LHC, the world's most powerful particle accelerator, was built by the European Organisation for Nuclear Research (Cern) to conduct experiments to test fundamental physics theories and to search for important new science such as the Higgs Boson. The particle beam machine, located at the border between France and Switzerland, was first powered up on 10 September, but the experiment had to be closed down on 19 September after a malfunction caused a leak of liquid helium.
Aymar said that at the moment the scientists at Cern do not know what caused the leak, as the equipment, which needs to be cooled to 1.9° above absolute zero to operate, still had to heat up to room temperature to be examined.
"We have to perform a test, but we cannot believe a magnet is faulty," Aymar told ZDNet.co.uk. "At the moment we think it is an [electrical] connection. We have thousands of connections and they can't all be tested in situ. We'll see after the magnet returns to room temperature."
James Gillies, head of communications at Cern, told ZDNet.co.uk that each magnet in the LHC was tested before it was switched on, but not the electrical and vacuum connections. "What seems to have happened is that one spliced between two connects failed, which broke the superconducting cable," he said.
Gillies described what Cern believes happened after the cable broke: "We had helium liquid leaking, going from a liquid to a gaseous state. A lot of helium was lost. It expands, so there was an increase in pressure, and a lot of mechanical damage. We're pretty sure the extent of the damage was manageable."
The LHC will come back online at the beginning of April, after a period of maintenance. Aymar said that from the 15 November to the beginning of April, all the accelerators are closed down each year for maintenance. The closure period also reduces the winter load on the French power grid, which normally supplies the experiment.
"In general we call [the closure period] 'consolidation', but really we have to do it otherwise they would fall apart," Aymar said.
Aymar spoke to ZDNet.co.uk at the official launch of grid computing at Cern on Friday. However, the grid-computing system has been running since 2003.