Application of RFSoC Technology for Beam Position Monitors at the SuperKEKB Storage Rings Injection Points

Abstract: In order to achieve its ambitious luminosity target, the SuperKEKB collider must achieve and sustain high beam currents on the order of Ampere in its storage rings. This requires continuous top-up injection and operation with a two-bunch injection scheme, injecting two 96 ns spaced bunches in a single injection cycle. An important input for tuning the injection beam is the position reading from a dedicated beam position monitor (BPM), located after the septum magnets, slightly upstream of where the injected and stored beams converge. Previously, the readout electronics used for these special BPMs were not capable of independent measurement of both bunches in the two-bunch injection mode and modification of the concerned devices and their firmware was not feasible. The opportunity was taken to develop a new readout device based on the AMD/Xilinx RF System on a Chip (RFSoC) platform with the goal of not only providing a sufficiently flexible and performant readout solution for the concerned BPMs, but also to evaluate and gain experience with the platform for beam monitor electronics applications. This paper is concerned with the details of this development as well as evaluation and operation of the developed device.