Performance of the beam position monitor for the Advanced Photon Source

Performance measurement and analysis of the Advanced Photon Source (APS) beam position monitor (BPM) electronics are reported. The results indicate a BPM resolution of 0.16 μm⋅mA/√Hz in terms of the single‐bunch current and BPM bandwidth. For the miniature insertion device (ID) BPM, the result was 0.1 μm⋅mA/√Hz. The improvement is due to the 3.6 times higher position sensitivity (in the vertical plane), which is partially canceled by the lower button signal by a factor of 2.3. The minimum single‐bunch current required was roughly 0.03 mA. The long‐term drift of the BPM electronics independent of the actual beam motion has measured at 2 μm/hr, which settled after approximately 1.5 hours. This drift can be attributed mainly to the temperature effect. Implications of the BPM resolution limit on the global and local orbit feedback systems for the APS storage ring will also be discussed.