Hadron Collider

The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. 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 (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. It is expected that it will address the most fundamental questions of physics, advancing our understanding of the deepest laws of nature. 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 the existence of the hypothesized Higgs boson and of the large family of new particlespredicted by supersymmetry. It is funded by and built in collaboration with over 10,000 scientists and engineers from over 100 countries as well as hundreds of universities and laboratories. The CMS paper reports that the increase in the production rate of charged hadrons when the center-of-mass energy goes from 0.9 TeV to 2.36 TeV exceeds the predictions of the theoretical models used in the analysis, with the excess ranging from 10% to 14%, depending upon which model is used. With a budget of US$9 billion, the LHC is one of the most expensive scientific instruments ever built. The total cost of the project is expected to be about US$4.4bn (as of Jan 2010) for the accelerator and US$1.1bn for the CERN contribution to the experiments.