The Large Hadron Colliderās reboot has been held up by a short circuit in one of the vast machineās magnets, potentially delaying the colliderās second run by weeks. There are three ways to fix it, say engineers at CERN, near Geneva in Switzerland.
The short circuit, which was first discovered over the weekend, is thought to be caused by a small piece of metal lodged inside an auxiliary piece of equipment on one of the magnets used to contain the LHCās accelerated beams. āItās a piece of metallic waste,ā says Paul Collier, CERNās head of beams. āWeāve got to get rid of it, we canāt power the circuit with this in place.ā
The LHC is cooled to just a few degrees above absolute zero, so the first fix ā tosimply reach in and pluck the offending object out of their collider ā is problematic.
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āIn a normal warm machine it would be very easy to just go in and lift off this piece of material,ā says Collier. But to warm up the LHC and cool it back down again would take several weeks.
So Collierās team is exploring two remote fixes. The first involves a high-tech version of the compressed air cans you might use to clean muck from inside your computer keyboard. The LHCās magnets are cooled by liquid helium, so it may be possible to turn the helium into a gas and blow it through the system to dislodge the metal.
āOne of the disadvantages is, the best you can hope for is you move the piece of material, hopefully somewhere it doesnāt cause any problems,ā Collier says.
Blow the fuse
The other fix is a bit more dramatic. The material is acting like a fuse, so it may be possible to blow that fuse by overloading it with electric current, burning it up in the process and removing the problem. āWeāre investigating exactly what would be required,ā says Collier. āWe think it is perfectly safe.ā
CERN is currently using X-ray imaging to determine the exact properties of the material and modelling whether the two remote fixes could work, which would sort out the problem in a matter of days, or if they will have to resort to heating and a more lengthy delay.
The LHC has been here before ā a failure in the same sector as the current fault shut down the machine for several months just a few days after it was first switched on in 2008. āThere is no relation between them, it just happens to be the same sector, itās a kilometre away,ā says Collier.
But physicists are confident they will be smashing particles at the highest energies weāve ever managed very soon.
āAll the signs are good for a great run 2,ā said CERN director general Rolf-Dieter Heuer. āIn the grand scheme of things, a few weeksā delay in humankindās quest to understand our universe is little more than the blink of an eye.ā
