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CERN and the Solar Tango- May 6th 2015
http://home.web.cern.ch/about/updates/2015/05/low-energy-collisions-tune-lhc-experiments
Low-energy collisions tune LHC experiments
At about half past nine CET this morning, for the first time since the Large Hadron Collider(LHC)
started up after two years of maintenance and repairs, the accelerator
delivered proton-proton collisions to the LHC experiments ALICE, ATLAS, CMS and LHCb at an energy of 450 gigaelectronvolts (GeV) per beam.
These collisions, which take place with each beam at the so-called
injection energy, that is, the energy at which proton beams are injected
into the LHC from the Super Proton Synchrotron,
enable the LHC experiments to tune their detectors. This process is
also an important step towards readying the accelerator to deliver beams
at 6.5 teraelectronvolts (TeV) for collisions at 13 TeV.