The Large Hadron Collider (LHC), which was at the origin of the discovery of the long-sought Higgs Boson in 2012 and which was shut down for upgrades in 2013, is now improved and ready to do science again, the scientists of the European Centre for Nuclear Research (Cern) said on 12 March in Geneva.

The first run of the particle accelerator, carried out at lower power, led in 2012 to confirmation of the existence of the Higgs boson particle, which explains how fundamental matter took on the mass to form stars and planets.

"We are really excited because we are entering a new phase of LHC after two years of heavy maintenance, heavy improvements of the whole accelerator's chain, of the whole infrastructures. And to restart the LHC now at a new energy, at a higher energy, which opens hopefully new windows depending of the kindness of nature of course. We are excited," said the Cern Director General, Rolf Heuer.

Scientists at the Cern physics research centre said the mystery dark matter that makes up 96 percent of the stuff of the universe will be a prime target for their souped-up Large Hadron Collider (LHC) in the coming years.

"There is still so many opened questions and so. For example what is all in the dark universe, what is the dark matter that we see out there in the universe?

"We know it has to be there. Can we create it and study it in the laboratory? This is going to be one of the big challenges for this coming run and indeed for the rest of the LHC program to look for that and other things which may be there.

"So we really try to be as open as possible, we'll take the data, the results will start to come, will start to flow in the summer. But then there will be many more results by the end of the year and later.

"When we get the next big discovery, the first big discovery, the next big discovery? We just don't know at this stage. We will see what nature has in store for us," said Dave Charlton, spokesperson for the Atlas experiment team that played a key role in tracking the long-sought Higgs boson in 2012.

The world's biggest particle collider is buried in a 17 miles tunnel and lies 300ft beneath the border between France and Switzerland.

The LHC was shut down on 14 February 2013 so that its collision capacity could be improved to 13 teraelectronvolts (TeV), 6.5 TeV for each of the two counter-rotating beams that zip around the ring, producing 10 times more data.

The Cern's collider has been undergoing a two-year refit and is now ready to start circulating proton beams. The first collisions are planned by May.