The Large Hadron Collider is the world's largest and most powerful particle accelerator (Image: CERN)

The world's biggest particle smasher was set today to start unprecedented experiments after a two-year upgrade to crank up energy levels to enable it to hopefully unlock more mysteries of the universe.The Large Hadron Collider (LHC), which was used to prove the existence of the Higgs Boson, which confers mass and is also known as the God particle, was undergoing last-minute checks and being readied for a new phase of experiments.The European Organisation for Nuclear Research (CERN) said everything was so far going according to plan at the giant lab, a 27-kilometre (17-mile) ring-shaped tunnel straddling the French-Swiss border."The LHC Operations team is increasing the energy of both beams to 6.5 teraelectonvolts (TeV)," a live blog by CERN said."The Operations team is preparing to refill the LHC once more," it added.On May 20, the LHC broke the record for energy levels colliding protons at 13 TeV for the first time.The LHC's previous highest energy for collisions was eight TeV, reached in 2012 before it closed for a sweeping revamp to prepare for further and more elaborate tests.Experiments at the collider are aimed at unlocking clues as to how the universe came into existence by studying fundamental particles, the building blocks of all matter, and the forces that control them.The LHC was used to prove the existence of the Higgs Boson, a discovery that earned the 2013 Nobel physics prize for two of the scientists who had theorised the existence of the Higgs back in 1964.The LHC allows beams containing billions of protons travelling at 99.9 per cent the speed of light to shoot through the massive collider 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.One teraelectronvolt is roughly equivalent to the energy of motion of a flying mosquito, CERN says on its website.But within the LHC, the energy is squeezed into an extremely small space, about a million times smaller than a mosquito. It is this intensity which causes the particles to be smashed apart.