• P.S. Yoon, D.P. Siddons
  BNL, Upton, Long Island, New York

We have developed a photodiode-based X-ray beam-position monitor with high-spatial resolution for use on the future beamlines at NSLS-II. A ring array of 32 Si PIN photodiodes were fabricated for a photon sensor, and a newly-designed HERMES4 ASIC die was integrated into the data-acquisition system. A series of precision measurements for electrical characterization of the Si-photodiode sensor and the ASIC die demonstrated that the inherent noise is sufficiently below tolerance levels. Following up with a series of modeling efforts including geometrical optimization, we have built prototype detectors. In this paper, we present the development of the new state-of-the-art X-ray BPM and experimental measurements performed on the existing X12A beamline at NSLS.