The Electron Synchrotron was the first high energy accelerator realized in Italy. It started operation in Frascati in 1959, delivering photon beams with energy between 0.4 and 1.1 GeV to the experiments, obtained by hitting the electron beam against a target inside the synchrotron vacuum vessel.
The 9 m diameter ring consisted of 4 bending magnets separated by 4 short straight sections. It was capable of delivering 4 msec pulses at 20 Hz, at an intensity of about 5 x 1010 particles per pulse. Important results have been obtained with the Electron Synchrotron in the study of pion physics, electron-proton diffusion, and the coherent photon production technique from electron bremsstrahlung in diamond crystals.