Greg Laden's Blog

An electrical connection between two of the all-important magnets arced. Sort of like a fuse blowing, but it was not a fuse and was not supposed to blow. The arcing of the circuit was sufficiently strong to poke a hole in part of the collider, causing the release of huge amounts of helium from the machine. This would have been bad if people were in the outer part of the tube (where they do a lot of their musical activities and generally have access to various parts of the machine). Naturally, safety plans would have people not in such areas during certain times, but it is not clear that this was the case during this incident; Among other things, the LHC is going to upgrade its presumably strident safety procedures even further.

In addition to the helium release, a bunch of icky carbony stuff went up and down the all-important tube for an as yet not exactly known difference. In other words, there was some smoke damage.

In addition to this, several magnets will also need to be repaired. The report released by CERN does not make clear (to me) how this damage to the magnets happened or exactly what it consists of, but I'm guessing that the electrical damage, while arcing in only one place, affected circuitry over a larger area. But I'm not sure of this: If anyone would like to elaborate or explain please do so!

There will be some changes made to respond to this incident. Safety upgrades as mentioned, but of more relevance to the engineering of the collider, there will be some changes in the circuitry and the structure. According to the report (and this is preliminary) there will be some structural changes to strengthen parts of of the barrier holding in the helium; there will be some changes to the circuitry so this arcing does not happen; and there will be changes to the sensors that detect problems in the electrical system that may prevent arcing or other problems if the electrical stuff starts messin' up again.

This is nothing like a worst case scenario. The LHC is normally shut down for a big chunk of time during the winter anyway, according to the operational plan, because Europe lacks sufficient electricity to run the darn thing during these months.

(Imagine a gaggle of seedy looking characters in a basement somewhere, sitting under a hanging lamp at an old table playing cards. Suddenly a large humming noise interrupts the game, and the light dims, then comes back up to full strength as the humming noise fades away. One of the card players, cigarette hanging from the corner of his mouth, says to the others in an ominous monotone:

...but I digress.)

The point is, no one could have realistically expected this machine to not break the first few times they switch it on. This will happen again. As it says in the report on this recent incident:

The technical parameters of the LHC are beyond precedent, and the energy stored in the superconducting magnets huge. Consequently, operation of this machine will always comprise a certain technical risk. ...

But some day ... they'll get their boson. CERN always gets its boson.

The full report is here, and a summary of the report at CERN is here.

This is how the LHC works.