Interaction region design and realization for the Beijing Electron Positron Collider

The Beijing Electron Positron Collider (BEPC) has been upgraded as a double-ring factory-like collider (BEPCII). A compact interaction region (IR), which is the most complicated region in the BEPCII, has been designed to afford a peak luminosity of 1×1033 cm−2 s−1 with an equal beam energy of 1.89 GeV, a cross angle of ±11 mrad, 93 bunches and maximum beam current of 0.91 A. All the components of the IR have been fabricated successfully. The design and realization of the interaction region for the BEPCII will be introduced in detail.