Design and performance of a high resolution, low latency stripline beam position monitor system

A high-resolution, low-latency beam position monitor (BPM) system has been developed for use in particle accelerators and beam lines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. It consists of three stripline BPMs instrumented with analogue signal-processing electronics and a custom digitizer for logging the data. The design of the analogue processor units is presented in detail, along with measurements of the system performance. The processor latency is $15.6\ifmmode\pm\else\textpm\fi{}0.1\text{ }\mathrm{ns}$. A single-pass beam position resolution of $291\ifmmode\pm\else\textpm\fi{}10\text{ }\mathrm{nm}$ has been achieved, using a beam with a bunch charge of approximately 1 nC.