The Large Hadron Collider, located underneath Geneva, Switzerland in a 27km. long circular tunnel, restarted 1930 GMT on Friday after a 14 month hiatus in which many speculated the machine would never do so because the ‘Higgs Boson’, a primordial sub-atomic particle, was so inimical to nature that it was capable of travelling back in time to prevent its own discovery.
This time though, it didn’t happen:
Engineers have made two stable proton beams circulate in opposite directions around the machine, which is in a tunnel beneath the French-Swiss border.
The team may try to increase the £6bn ($10bn) collider’s energy to record-breaking levels this weekend.
The LHC is being used to smash together beams of protons in a bid to shed light on the nature of the Universe.
It is the world’s largest machine and is housed in a 27km-long circular tunnel.
During the experiment, scientists will search for signs of the Higgs boson, a sub-atomic particle that is crucial to our current understanding of physics. Although it is predicted to exist, scientists have never found it.
Dozens of giant superconducting magnets that accelerate the particles at almost the speed of light have had to be replaced after faults developed just days after the collider was inaugurated last year.
Operated by the European Organization for Nuclear Research (Cern), the LHC will create similar conditions to those which were present moments after the Big Bang.
The BBC’s Pallab Ghosh in Geneva says the restart of the collider was the moment the scientists had been waiting for.
It means they can once again go in search of the new discoveries they believe will roll back the frontiers of understanding our universe, says our correspondent.
“It’s great to see beams circulating in the LHC again,” said Cern’s director-general Rolf Heuer.
We’ve still got some way to go before physics can begin, but with this milestone we’re well on the way.”Record attempt
The beams themselves are made up of “packets” – each about a metre long – containing billions of protons. But they would disperse if left to their own devices.
Electrical forces had to be used to “capture” the protons. This keeps them tightly huddled in packets, for a stable, circulating beam.
Engineers had not been expected to try for a circulating beam before 0600 GMT on Saturday.
James Gillies, Cern’s director of communications, told BBC News: “It happened faster than anyone could have dreamed of.”
“Everything went very smoothly.”
The first beam was sent all the way round the LHC’s circumference 100m underground after 1930 GMT on Friday.
Engineers captured this clockwise-circulating beam at 2100 GMT. A second anti-clockwise beam made a full circle of the LHC at 2153 GMT and was captured at 2310 GMT.
Dr Gillies said that if everything continued to go well, Cern might try to reach a record-breaking beam energy of 1.2 trillion electron volts this weekend.
Only the Tevatron particle accelerator in Chicago, US, has approached this energy, operating at just under one trillion electron volts.
But other team members want to keep the beam circulating at low energy and try for the machine’s first proton beam collisions.
“The LHC is a far better understood machine than it was a year ago,” said Steve Myers, Cern’s director for accelerators.
“We’ve learned from our experience, and engineered the technology that allows us to move on. That’s how progress is made.”
So far, so good.
But what will happen when real science begins and maybe, just maybe, the Higgs Boson will rear its ugly head?
Will Time be on our side?