Performance Test of the Next Generation X-Ray Beam Position Monitor System for the APS Upgrade

The Advanced Photon Source is developing its next major upgrade (APS-U) based on the multi-bend achromat lattice. Improved beam stability is critical for this upgrade and will require keeping short-time beam angle change below 0.25 μrad and long-term angle drift below 0.5 micro-radian. A reliable white x-ray beam diagnostic system in the front end is a key part of the planned beam stabilization system for the APS-U. This system includes an x-ray beam position monitor (XBPM) based on x-ray fluorescence (XRF) from two specially designed GlidCop A-15 absorbers, a second XBPM using XRF photons from the Exit Mask, and two white beam intensity monitors using XRF from the photon shutter and Compton-scattered photons from the front end beryllium window. We present orbit stability data for the first XBPM used in the feedback control during user operations, as well as test data from the second XBPM and the intensity monitors. The data demonstrated that the XBPM system meets the APS-U beam stability requirements.