Hwang, J.G. Kuszynski, J. JACoW Publishing Geneva, Switzerland 978-3-95450-201-1 10.18429/JACoW-IBIC2018-WEPB03 English 434-437 WEPB03 diagnostics SRF operation linac cavity Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-IBIC2018-WEPB03 http://jacow.org/ibic2018/papers/wepb03.pdf Since particle losses by beam halo induced by space charge force and scattering of trapped ions are critical issues for superconducting-linac based high power machines such as BERLinPro, a halo monitor is demanded to monitor and control particle distribution at the level of 10⁻⁴ ~ 10⁻⁵ of the core intensity. A coronagraph-based halo monitor was adopted and the first prototype has been designed as a demonstrator system aimed at resolving a halo-core contrast in the 10⁻³ to 10⁻⁴ range. This monitor was tested at BESSY II with various operation modes such as Transverse Resonance Island Buckets (TRIBs) and Pulse-Picking by Resonant Excitation (PPRE). We show our design parameters, experimental criterion, and experimental results.