Development of event building farm for SuperKEKB

In order to search new physics beyond the standard model using B meson decays, we are planning SuperKEKB with a luminosity 5/spl times/10/sup 35/cm/sup -2/s/sup -1/. To tolerate a high trigger rate of 10/spl sim/30 kHz and to handle a large number of unified readout modules, we design a new event building farm. In order to validate the design, we have set up a prototype event building farm for SuperKEKB and measured the performance. The prototype of readout part works with at least 10 kHz event rate. For a design value, we find that the further software improvement and the faster PC are needed. Event distribution part of the prototype tolerates the high event rate by increasing the number of event builder units. We conclude that the developed event building farm tolerates the high rate by adding event building units to keep up with gradual increase in luminosity.