The main structure of the mechanical system of Beijing Spectrometer (BES III) was completed and passed experts' appraisal on Dec 12. This is another breakthrough attained in the upgrade project of the Beijing Electron Positron Collider (BEPC).

The Beijing Spectrometer (BES III) is a universal detector on the BEPC, which is built to improve measurement accuracy and eliminate system errors. The BES III, compromising equipment such as precise drift chamber and time-of-flight counter, will undertake tasks of signal sampling, amplification and precision measurement of parameters.

"The completion of the main structure of BES III's mechanical system is a landmark in the upgrade project," noted researcher Wang Yifang, deputy president of Institute of High Energy, CAS. The BES III will perform precision measurement in tau-charm energy zone and explore more new physical phenomena. A number of new fruits are expected to be attained, making China maintain the leading position in tau-charm physic research.

The upgrade of the BEPC began in April 20004. The upgraded BEPC will maintain its leading position among accelerators of the same kind in the world and become one of the most advanced double ring colliders in the world.

At present the tasks of the stage 1 - upgrade of the linear accelerator, the colliding area and the transformer substation - have been accomplished. It is predicted that the upgrade of BES III will finalize in March 2007.

By People's Daily Online