LHCb scintillating tiles

The electromagnetic calorimeter used in LHCb is a sandwich of lead plates and scintillating tiles. Incoming particles interact with the lead, creating a shower of new particles. This shower goes on to interact with the plastic tiles where its energy is transformed into tiny flashes of light, called scintillations. All this light is then collected in optical fibres which transport it to a photomultiplier tube that converts the light signal into a pulse of electrical current. The resulting signal reveals the energy of the original particle. 3300 such modules combine to make up the first layer of LHCb calorimeters.