Upgrade of abort trigger system for SuperKEKB

The beam abort system was installed in KEKB to protect the accelerator equipment and the Belle detector, and for radiation safety, from high current beams. For SuperKEKB, the new abort trigger system has been developed. It collects more than 130 beam abort request signals and issues the beam abort trigger signal to the abort kickers. The request signals are partially aggregated in local control rooms located along the SuperKEKB ring and finally aggregated in central control room. In order to increase the system reliability, the VME-based module and the E/O module was developed, and all the abort signals between the modules are transmitted as optical signals. The system also has the timestamp function to keep track abort signal received time. The timestamps are expected to contribute to identify the cause of the beam abort. Based on the feasibility tests with a prototype module, the new module design has been improved and fixed. This paper describes the details of the new abort trigger system. (author)