Progress toward a hard x-ray insertion device beam position monitor at the Advanced Photon Source

Long-term pointing stability at synchrotron light sources using conventional rf-based particle beam position monitoring is limited by the mechanical stability of the pickup electrode assembly. Photoemission-based photon beam position monitors for insertion device beams suffer from stray radiation backgrounds and other gap- dependent systematic errors. To achieve the goal of 500-nanoradian peak-to-peak pointing stability over a one-week period, the development of a photon beam position detector sensitive only to hard X-rays (> several keV) using copper X-ray fluorescence has been initiated. Initial results and future plans are presented.