The world's largest machine developed by European Organisation for Nuclear Research (CERN) started operating last evening, 14-months after the fault caused one tonne of helium to leak into the 27-km long tunnel that houses it.
"It's great to see beams circulating in the LHC again," CERN director-general Rolf Heuer said.
"It happened faster than anyone could have dreamed of. Everything went very smoothly," said James Gillies, the organisation's director of communications.
With the help of the LHC, scientist want to learn more about 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.
"This giant machine part will try to detect the elusive Higgs boson," Gillies said adding if everything continued to go well, CERN might try to reach a record-breaking beam energy of 1.2 trillion electron volts this weekend.
The LHC will create conditions similar to those which were present moments after the Big Bang by smashing together beams of protons, BBC reported.
The Big Bang is the cosmic explosion hypothesised to have marked the origin of the Universe.
The CERN has spent around 24 mn pound on repairing the machine.