LHC is back
After a winter hiatus, the Large Hadron Collider is running again with its 7 TeV proton collision program (and the US/LHC Event of the Week has resumed as well). This event is from March 13, the first day of collisions in 2011. In the side view at the bottom, you can see evidence of multiple vertices: each one is from an independent proton-proton collision. As the LHC reaches higher collision rates, there will be more multi-vertex events like this, where the collision of interest has to be disentangled from the others in order to analyze the data.
Credit: ATLAS Experiment© 2011 CERN