LHC Magnet Failure

this is not the sort of thing we'd like to see happening so soon before the LHC is expected to start running: on tuesday, a test of one of the accelerator's quadrupole magnets, which are used to focus the particle beam, failed miserably. here is an explanation of what happened from fermilab's john conway at cosmicvariance:

"The failure occured during a test which simulated what the magnet might experience during a “quench” which is when some part of the superconducting cable inside the magnet suddenly goes “normal” and then resists the flow of the huge current in it. This releases heat, of course, causing the rest of the superconducting material to go normal. Liquid helium boils rapidly, creating large asymmetric pressures inside the magnet cryostat. These pressures can reach 20 bar, and it was during a 20-bar test that this particular magnet failed. No one was in the LHC tunnel when it happened - it must have been quite a sight, and sound, though."

apparently, four reviews of the magnets were carried out at fermilab (where they were built) between 1998 and 2002 by experts from a number of different laboratories, yet apparently these reviews didn't address the issue of asymmetric pressures. read more about this in the fermilab statement. oh and i like this: why do physicists want to study particles? (a crucial question to ask given LHC's 3.8 billion dollar price tag.) the image above shows one of the quadrupoles being installed in 2006. (image credit: fermilab)