After two years of upgrade, the CERN's Large Hadron Collider has started. The LHC was shut down in 2013. The team reported that LHC has started smashing protons for the first time. It was shut down for a two-year upgrade planned to push the field of particle physics to new frontiers.

The first runs of particle collisions were at comparatively low energy levels and as part of testing and preparation for the next round of experiments at CERN. According to experts, beams of protons were sent in opposite directions about the 17-mile circumference of the LHC 450 and after that smashed together with gigaelectronvolts (GeV) of energy.

It is expected that the current round of experiments will ultimately reach energies of 6.5 teraelectronvolts (TeV) per beam to yield collisions at 13 TeV. In addition to Atlas, the LHC contain three other detectors. The three are CMS, Alice and LHCb and all of which recorded collisions in the new tests. The low power collisions are enabling physicists to tune and calibrate their experiments in preparation for the higher-energy runs.

"So just as the LHC team tests each component, system, and algorithm one after the other, the experiments go through checklists that confirm that everything is fully functional and no mistakes, bugs or failures are present when collisions are delivered at 13 TeV", CERN said in a release.

The scientists at the LHC were in news in 2012 with their discovery of the Higgs boson. There is a possibility that the new high-power experiments could provide evidence of the existence of dark matter particles or give clues to why there is more matter in the universe than antimatter.

According to the experts, LHC operations are in middle through a scheduled 8-week period of testing of all systems to make sure that they are working as anticipated in preparation for high-energy collisions set to start in June.