A piece of baguette dropped on the overground part of the machinery resulted in parts of the machine overheating. The Register reports that temperatures in part of the LHC's circuit climbed to almost 8 Kelvin - significantly higher than the normal operating temperature of 1.9 Kelvin, and close to the temperature at which the LHC's niobium-titanium magnets are likely to "quench", or cease superconducting.
According to The Reg, readers monitoring the collider's operational data online noticed that temperatures started to rise in the early hours of Tuesday morning. While initial inquiries to CERN were met with assurances that everything was fine and the change in temperature was a result of routine testing, Dr. Mike Lamont told reporters that the problem was actually caused by "a bit of baguette on the busbars." CERN is assuming a bird dropped the offending piece of bread.
The incident happened while the LHC wasn't even on, which raises the question, "what would have happened had the collider been in operation?" Well, nothing hopefully. Lamont told the Register that the climb in temperature would have been noted and the LHC's beams would have been diverted to "dump caverns" lying a little off the main track of the LHC.
The dump caverns are large, artificial caves, which would channel the power into a "dump core." The core is a 7m-long graphite block encased in steel, water cooled and then further wrapped in 750 tonnes of concrete and iron shielding. According to Lamont, the dump core would become extremely hot and quite radioactive, but with massive amounts of shielding and a huge amount of solid granite between the dump caverns and the surface, " Nobody up top, except the control room staff, would even notice."
If there were no dump caverns? LHC's niobium-titanium magnets are likely to cease superconducting at around 9.6 Kelvin. When circulating, each of the two beams of hadrons pack enormous amounts of power and if they were to suddenly stop, all the energy would have to go somewhere. The Reg equates the damage to being rammed by an aircraft carrier.