The beam energy measurement system for the Beijing electron-positron collider
arXiv:1109.5771 · doi:10.1016/j.nima.2011.08.050
Abstract
The beam energy measurement system (BEMS) for the upgraded Beijing electron-positron collider BEPC-II is described. The system is based on measuring the energies of Compton back-scattered photons. The relative systematic uncertainty of the electron and positron beam energy determination is estimated as 2 \cdot 10^{-5}. The relative uncertainty of the beam's energy spread is about 6 %.