Design of an undulator white beam profiler and test results on the Advanced Photon Source beamline (abstract)

At the Advanced Photon Source (APS), each insertion device (ID) beamline front end has two x-ray beam position monitors (XBPMs) to monitor the x-ray beam position for both the vertical and horizontal directions. The XBPMs measure photoelectrons generated by the chemical vapor deposited-diamond-based sensory blades and deduce the beam position by comparison of the relative signals from the blades [D. Shu, B. Rodricks, J. Barraza, T. Sanchez, and T. M. Kuzay, Nucl. Instrum. Methods. Phys. Res. A 319, 56 (1992)]. Performance challenges for an undulator XBPM during operation are contamination of the signal from the neighboring bending-magnet sources and the sensitivity of the XBPM to the ID gap variations. Problems are exacerbated because users change the ID gap during their operations, and hence the percentage level of the contamination in the front-end XBPM signals varies. The smart XBPM system partially solved these problems [D. Shu, H. Ding, J. Barraza, T. M. Kuzay, and M. Ramanathan, J. Synchrotron Radia...