ATLAS catches a Z
In this ATLAS 7 TeV event display, two straight tracks in the tracker (prominent yellow lines) indicate two energetic particles coming from the decay of an object made in the proton-proton collision. These tracks end as yellow splotches where the particles deposit all their energy in the electromagnetic calorimeter (green area); these deposits are seen as yellow towers in the "lego plot" at the top right. The reconstructed mass of 89 GeV is close enough to the accepted mass of the Z boson to declare the "object" to be a good candidate for a Z, which has decayed into an electron and a positron.
Copyright 2010 The ATLAS Experiment at CERN Collaboration