Fig. 13

ATLAS Pile-up. a and b shows the pile-up (multiple interaction points) situation from proton-proton collision at the LHC inside the ATLAS detector in a region that is only about 5 cm wide. The pile-up in a has 25 interaction points and in b has 17 interactions points, where only one interaction point produced the decay tracks from the Z Boson. Image courtesy ATLAS Collaboration at CERN