Two circulating beams bring first collisions in the Large Hadron Collider
On November 23, the Large Hadron Collider (LHC) circulated two beams simultaneously for the first time, allowing the operators to test the synchronization of the beams and giving the experiments their first chance to look for proton-proton collisions. With just one bunch of particles circulating in each direction, the beams can be made to cross in up to two places in the ring. From early in the afternoon, the beams were made to cross at points 1 and 5, home to the A Toroidal LHC Apparatus (ATLAS) and Compact Muon Solenoid (CMS) detectors, both of which were on the lookout for collisions. Later, beams crossed at points 2 and 8, the Large Ion Collider Experiment (ALICE) and the Large Hadron Collider beauty (LHCb).
