Electromagnetic cluster reconstruction in LHCb

We present electromagnetic cluster reconstruction in the LHCb experiment. This detector is located at CERN, the European Laboratory of Particle Physics, in Geneva, at one of the four interaction points of the largest proton proton collider of the world, LHC. Among the huge quantity of produced particles, the detector must have capabilities to identify electromagnetic particles (such as electrons, photons) which are present in the decay products. This has to be done for each collision of protons i.e. at 40 MHz because high energetic particles are a clear signature of events of interest and they are used for the first trigger system of the experiment. We will describe how the architecture of the calorimeter detector has been designed to fulfil these requirements. In addition this information has to be refined for further analysis. This is done using automaton cellular.