Physicists working with the Large Hadron Collider particle accelerator (LHC) say the short circuit that delayed the start of the giant machine's second run has been fixed.
The glitch – caused by metal fragments intermittently shorting circuits in one of the machine's huge supercooled magnets – has been corrected and the LHC will soon be back in operation, following a two-year shutdown for maintenance and upgrading.
Engineers sent an electrical pulse through the affected circuit, successfully burning away the fragments causing the problem.
"It's a bit like deliberately blowing a fuse," explained Paul Collier, head of beams at CERN, the European particle physics laboratory near Geneva, Switzerland, which operates the LHC.
Subsequent measurements showed the repair worked, with engineers testing the circuits at high voltages.
"There's no short there now, even at high voltages," Collier said.
If the repair attempt had been unsuccessful, the start of the LHC's run could have been pushed back by months. Removing the fragments by physical means would have required bringing the magnet – which is cooled to near absolute zero – up to room temperature for the repair, and then cooling it back down to its operating temperature. The electrical "blasting" of the fault was something of an experiment, done in the hopes of a quicker fix.
"It looks good," Collier said. "We hope to be ready to take beams sometime during the weekend."
Those beams will accelerate particles around the 16-mile ring of the LHC, smash them together and recreate the conditions that existed in the universe shortly after the Big Bang.
Physicists have been using the LHC to push the boundaries of science, famously detecting the Higgs boson – the fundamental particle underlying the Standard Model of physics – in 2012.
The upgrades performed over the last two years will allow particles to collide at almost the speed of light, and at energy levels twice that of the LHC's first run.
One of the goals for the new experimental runs of the LHC will be confirming the existence of dark matter, the unseen material thought to comprise 96 percent of the mass in the universe. Dark matter has thus far only been detected by its gravitational influence on the visible universe.
There are still many tests to be completed in advance of the first proton particle collisions at new, higher energy levels. CERN scientists say they will probably take place in May.
