Development of event building farm for SuperKEKB

For the purpose of new physics search in rare B meson decays, an upgrade of the KEKB accelerator is being planned where the luminosity becomes more than ten times higher. The trigger rate with the increased luminosity is expected to reach up to 30 kHz with the event size of /spl sim/300 kB. A new event builder is designed to cope with the condition by modularizing the system currently used in the Belle experiment and by operating multiple units in parallel. A test bench is built to study the new design and results of performance tests are reported.