A scientist walks in a tunnel inside the European Organisation for Nuclear Research (CERN) Large Hadron Collider during maintenance works near Geneva on July 19, 2013

The world's biggest particle collider is set to restart this weekend after a two-year upgrade, the European Organisation for Nuclear Research (CERN) said Thursday.

Engineers at the Large Hadron Collider (LHC) hope to introduce two proton beams, the source material for sub-atomic smashups, as part of the recommissioning process.

"The first beams could be circulating in the machine sometime between Saturday and Monday," CERN said in a statement.

"We are confident of being able to restart the machine over the weekend, as all of the tests performed so far have been successful," said Frederick Bordry, CERN's director for accelerators and technology.

A short-circuit in one of the LHC's magnet circuits last Saturday had delayed the eagerly-awaited restart.

The LHC comprises a 27-kilometre (17-mile) ring-shaped tunnel straddling the Franco-Swiss border, in which two beams of protons are sent in opposite directions.

Powerful magnets bend the beams so that they collide at points around the track where four laboratories have batteries of sensors to monitor the smashups.

The sub-atomic rubble is then scrutinised for novel particles and the forces that hold them together.

In 2012, the LHC discovered the Higgs Boson, the particle that confers mass, earning the Nobel prize for two of the scientists who, back in 1964, had theorised its existence.

Since then, the giant machine has been undergoing an upgrade to beef up its maximum collision capacity from eight teraelectronvolts (TeV) to 14 TeV—seven TeV for each of the two counter-rotating beams.

The startup work will see engineers attempt to inject two beams into the tunnel at a lower energy of 450 gigaelectronvolts, but there will not be collisions.

If all goes well, "particle collisions at an energy of 13 TeV could start as early as June," CERN said.

During the next phase of the LHC programme, researchers will probe a conceptual frontier called new physics, with enigmatic "dark matter" the big area of interest.

Ordinary, visible matter comprises only about four percent of the known Universe.

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