The electromagnetic calorimeter is the main detector of the four detectors of the HERMES PID system.

Its functions are:

to provide a first-level trigger for scattered positrons, based on energy deposition in a localized spatial region;

to separate positrons from pions with a rejection factor of more than 10 at the first-level trigger and an additional factor of more than 100 in event reconstruction analysis;

to provide a measurement of the energy of DIS positrons;

to measure the energy of photons from radiative processes or from \pi0 and \eta decays;