The world's largest particle accelerator is to restart on Monday following a technical break and glitches in the machine.
The first proton beams of 2010 were circulated in the Large Hadron Collider (LHC) on Saturday, Cern said on Monday. The machine had been undergoing technical maintenance for 10 weeks.
However, soon after the beams were circulated on Saturday, the beams had to be stopped to allow maintenance to cryogenic systems which help regulate the superconducting magnets, according to Cern.
"Engineers had to access the filters for the cryogenic systems," a spokesperson for the organisation said. "They are fixing that, and we expect to beams to be circulating again tonight."
The beams will be injected at an energy of 450 gigaelectron volts (GeV). The beam energy will be slowly increased until it reaches 3.5 teraelectron volts (TeV) per beam, which is expected to happen in 2 to 4 weeks.
Cern said at the beginning of February that it plans to run the LHC for up to two years at 3.5 TeV, then shut the machine down prior to preparing it to run at 7 TeV per beam.
The LHC has been designed to conduct experiments that will reveal new physics, including proving the existence of the Higgs boson, a hypothetical elementary particle.
The LHC as a project has had mixed fortunes. It was forced to shut down shortly after powering up in 2008 following a helium leak, and was then subject to various delays to its restart. However, when it did start up again in November it quickly became the world's most powerful particle accelerator, before being halted again for maintenance.