LHC BIG BANG machine forced to halt

Plans to begin smashing particles at the Large Hadron Collider (LHC) may be delayed after a magnet failure forced engineers to halt work.

The failure, known as a quench, caused around 100 of the LHC's super-cooled magnets to heat up by as much as 100C.

The fire brigade were called out after a tonne of liquid helium leaked into the tunnel at Cern, near Geneva.

The LHC beam will remain turned off over the weekend while engineers investigate the severity of the fault.

A spokesman for Cern told the BBC it was not yet clear how soon progress could resume at the £3.6bn ($6.6bn) particle accelerator.

While the failure was "not good news", he said glitches of this kind were not unexpected during testing.

Delays

The first beams were fired successfully around the accelerator's 27km (16.7 miles) underground ring over a week ago.

Superconducting magnets are cooled down using liquid helium

The crucial next step is to collide those beams head on. However, the fault appears to have ruled out any chance of these experiments taking place for the next week at least.

The quench occurred during final testing of the last of the LHC's electrical circuits to be commissioned.

At 1127 (0927 GMT) on Friday, the LHC's online logbook recorded a quench in sector 3-4 of the accelerator, which lies between the Alice and CMS detectors.

The entry stated that helium had been lost to the tunnel and that vacuum conditions had also been lost.

It added that the Cern fire brigade had been called to the scene.