The Large Hadron Collider (LHC) is the world’s largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics advancing the understanding of the deepest laws of nature. The LHC lies in a tunnel 27 kilometres (17 mi) in circumference as much as 175 metres (574 ft) beneath the Franco-Swiss border near Geneva Switzerland. This synchrotron is designed to collide opposing particle beams of either protons at an energy of 7 teraelectronvolts (7 TeV or 1.12 microjoules) per particle or lead nuclei at an energy of 574 TeV (92.0 µJ) per nucleus. The term hadron refers to particles composed of quarks. The Large Hadron Collider was built by the European Organization for Nuclear Research (CERN) with the intention of testing various predictions of high-energy physics including testing for the existence of the hypothesized Higgs boson and of the large family of new particles predicted by supersymmetry. It was built in collaboration with over 10000 scientists and engineers from over 100 countries as well as hundreds of universities and laboratories. On 10 September 2008 the proton beams were successfully circulated in the main ring of the LHC for the first time but 9 days later operations were halted due to a serious fault. On 20 November 2009 they were successfully circulated again with the first recorded proton–proton collisions occurring 3 days later at the injection energy of 450 GeV per beam. After the 2009 winter shutdown the LHC was restarted and the beam was ramped up to half power 3.5 TeV per beam (i.e. half its designed energy). On 30 March 2010 the first planned collisions took place between two 3.5 TeV beams a new world record for the highest-energy man-made particle collisions. The LHC will continue to operate at half power for some years it will not be running at full power (7 TeV per beam) until 2014.