On July 4, 2012, CMS and ATLAS provided fireworks of a different sort. Both claimed discovery of a new particle that may well be the Higgs. This CMS event from the 2012 run of LHC shows two photons: the green towers are energy deposits in the electromagnetic calorimeter and the two yellow dashed lines project the photon trajectories. (The photon has no charge and so is not directly measured by the tracker.) The bulk of the data used to make the discovery comes from diphoton events like this. Learn more: CMS article, ATLAS article.
Credit: Copyright CERN on behalf of the CMS Collaboration.