After nearly two years of maintenance and repair, the Large Hadron Collider (LHC) has been fired up for a series of unprecedented experiments.
The world's biggest particle smasher has undergone a lengthy upgrade to increase the energy levels to enable it to hopefully unlock more mysteries of the universe.
The laboratory's 17-mile (27.4km) ring-shaped tunnel has been undergoing last-minute checks so it is ready for the new phase of experiments.
The LHC was previously used to prove the existence of the Higgs Boson - also known as the God particle - which gives other particles mass.
Scientists are hoping to take their experiments a step further this time around, after repairs were completed in April.
Due to a software issue the first beams sent this morning had to be stopped, but the experiments are set to resume later.
The European Organisation for Nuclear Research (CERN) said everything was so far going according to plan at the giant lab, which straddles the French-Swiss border.
Protons race around the LHC tunnels at just below the speed of light. The energy released when they collide is used to spark the creation of new particles.
The new experiments are set to take data at the unprecedented energy of 13 tera-electronvolts (TeV) - close to double the collision energy of the LHC's first three-year run.
With the ability to tap into higher energy, the scientists hope to explore the mysterious realms of "new physics" that could yield evidence of hidden extra dimensions and dark matter.
As well as searching for dark matter, LHC scientists hope to create more and possibly different strains of Higgs Boson, investigate anti-matter and test the theory of "supersymmetry", which predicts that every known particle has a more massive hidden partner.
The LHC is the most powerful atom-smasher ever built.
CERN Director General Rolf Heuer said, “the first 3-year run of the LHC, which culminated with a major discovery in July 2012, was only the start of our journey. It is time for new physics!
"We have seen the first data beginning to flow. Let’s see what they will reveal to us about how our universe works," he added.
