Calorimetry for MUonE.

The MUonE Collaboration aims at a very precise measurement of the muon-electron elastic scattering cross-section, to extract the leading hadronic contribution, due to vacuum polarization, which enters in the calculation of the muon anomalous magnetic moment. The experiment will consist of a cascade of 40 tracking stations, each composed of a low-$Z$ target and few silicon trackers, and an electromagnetic calorimeter. The role of the calorimeter and the status of the R&D will be illustrated, with emphasis on the challenges implied in the measurement of the electron energy in the MUonE setup.