The Beijing Electron-Positron Collider II (BEPCII) is IHEP’s main accelerator facility. BEPCII is a two-ring e+e- collider running in the tau-charm energy region (Ecm = 2.0-4.2 GeV), which, with a design luminosity of 1 × 1033 cm-2s-1 at a beam energy of 1.89 GeV, is an improvement of a factor of 100 over its successful predecessor, BEPC. It can run in collision mode, allowing the BESIII experiment to collect data, or in synchrotron radiation mode, providing beam for the Beijing Synchrotron Radiation Facility.

The original BEPC, which completed construction in 1988, was China’s first high-energy particle accelerator. After several years of successful running, including significant achievements in the charm physics field, such as the tau mass measurement, the upgrade to BEPCII began in 2004. Construction was completed in 2008, and running began in 2009, after overcoming the technical difficulties of building a double-ring collider in the narrow, short-circumference BEPC tunnel. In 2016, BEPCII reached its design luminosity of 1 × 1033 cm-2s-1, a world record for this energy range.

In collision mode, BEPCII has produced the world’s largest samples of J/ΨandΨ’ events, as well as events at a range of other energy points. Using these samples, the BESIII experiment has made important discoveries including the discovery of the Zc(3900) and other so-called “XYZ” states.

In synchrotron radiation mode, up till the end of 2016 the accelerator has provided over 15000 hours of dedicated synchrotron radiation light to experiments from 278 institutions around the world, leading to almost 2500 publications.

Contact: yumeijuan

Email: yumj@ihep.ac.cn