The Belle event building system

We have built a barrel-shifter type event builder for the Belle experiment and operated it successfully. This is the first experience applying the barrel-shifter type event builder to the real experiment. The type of our event builder is a global-traffic control. The Belle event builder is required to be scalable up to 11 source nodes (detector readout subsystems) and six destination nodes (online computer farm subsystems). The average event size is estimated to be 30 kbyte and maximum trigger rate is 500 Hz. This event builder has been operated with full detectors since Dec. 1998. We have shown that the barrel-shifter type event builder is applicable for this size of experiment.