The Three-Level Event Building System for the Belle II Experiment
S. Y. Suzuki, Satoru Yamada, R. Itoh, Marcelo Nakao, T. Konno, T. Higuchi, K. R. Nakamura · IEEE Transactions on Nuclear Science · 2015
Belle II, an experiment designed to search for physics beyond the standard model in the decay of B mesons, will soon start operation at the Super KEKB e+e-collider. The trigger rate is expected to be 30 kHz with a margin of 10 kHz, and the raw data rate will exceed 30 GB/s. Since the system will be unable to record all data on its storage system, online reduction is required. We have developed a three-level event building system using inexpensive switches and software for traffic smoothing, enabling online event processing at a reasonable cost. The data will be recorded on the storage system about 3 GB/s after rate reduction. This paper describes the architecture and the verification result in actual beam tests.