Abstract:

This paper describes the design of IP orbit feedback system for BEPCII.In the BEPCII the electron and positron beams circulate in the separate rings and collide only at the southern interaction point (IP)with a crossing angle, thus an IP orbit feedback system based on the beam-beam deflection technique is necessary for maintaining an optimum beam collision condition at the IP.Moreover, in order to measure the positions of both positron and electron in the IP at the same time, two special BPMs with 8-button electrodes will be installed at the both side of interaction point.The working principle of the special BPM and the simulation results with finite element method are also described in this paper.

Key words: IP, feedback, BEPCII, BPM