Today the 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 ATLAS and CMS detectors,
both of which were on the look out for collisions. Later, beams crossed at
points 2 and 8, ALICE and LHCb.