LHC steps up on the bunches
According to the US LHC team’s twitter feed, the Large Hadron Collider is now running with 13 bunches of protons per beam. That’s a significant step up from the single bunch of protons per beam that the LHC began operations.
Each bunch of protons is moving around the 27-kilometre-long tunnel at near the speed of light, completing 11,245 trips round the ring every second. There is one beam moving clockwise, and another counterclockwise. At four points along the ring, these beams cross and the protons bunches collide.
Each time two bunches cross paths, about 200 billion protons are involved. However, only about 20 protons actually collide, the rest just continue unimpeded. When the LHC will be running at full-tilt, with about 2808 bunches in each beam, then even though just 20 of the 200 billion protons collide, the sheer number of bunches crossing per second means that about 100 billion particles per second will be produced at each of the four collision points of the LHC.
That’s where detectors like ATLAS and CMS will be monitoring particle tracks, hoping to find the Higgs, dark matter particles, signs of supersymmetry or even extra dimensions.