Beijing Electron–Positron Collider II

The construction of this collider was considered so important that then vice-premier Deng Xiaoping attended the groundbreaking in 1984 and returned in 1988 as the machine neared operation.

[3][4][5] The original Beijing Electron Positron Collider was commissioned in 1989 and decommissioning began in 2000 as plans were developed for BEPC II, although operation continued until 2004.

The shape of the BEPC has been described as a tennis racquet, with a linac with a beam energy of from 1.5 to 2.8 GeV serving as the handle, injecting counter-rotating beams of particles into a storage ring at the head, giving collision energies in the range from 3.0 to 5.6 GeV.

Major accomplishments of the original BEPC included precision measurement of the Tau mass.

BES III uses a large superconducting solenoid to provide a 1-tesla magnetic field, and also features a helium gas-based tracking chamber and an electromagnetic calorimeter using 6240 caesium iodide crystals.