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Large Hadron Collider passes tricky beam tests

Preparing for the historic Wednesday start-up, physicists send protons further round the 27-kilometre ring than ever before

You could be forgiven for thinking that a big red button will be pressed on Wednesday, and hey presto, collisions at the Large Hadron Collider will begin. In fact, the particle smasher has been limbering up for weeks. As New Scientist went to press, physicists were sending protons further round the 27-kilometre ring than ever before, and were on track to perform the first historic laps.

At 5 am on 6 September, after a night spent grappling with glitches in the LHC’s vast safety system, a crew successfully fired a pilot beam 6.6 kilometres around the counter-clockwise beam pipe and straight into the LHCb detector – one of the experiments that will record collisions. That’s twice the distance of the last injection test two weeks ago. They’ve now fired the beam through roughly a third of the machine without having to adjust the magnets. “This has come as a great surprise,” says Steve Myers, CERN’s head of accelerators and beams.

Then the beam was kicked 600 metres down a side tunnel into a 1000-tonne block of graphite, concrete and steel designed to absorb its energy. “The beam was not perfectly centred, but it was right on the block,” said machine operator Jorg Wenninger. When the LHC is operating at full whack such beam “dumps” will be vital to prevent the protons drilling holes in the machine and putting it out of action for months.

On 7 September, physicists sent a beam 10 kilometres to a concrete stopper in front of the CMS experiment, presenting the giant apparatus with its first smashed-up particles.

Come October we can expect the first high-energy collisions – with a combined energy of 10 teraelectronvolts.

The Large Hadron Collider – find out more about the world’s biggest experiment in our cutting-edge special report.