The BaBar Event Building and Level-3 Trigger Farm Upgrade

The BaBar experiment is the particle detector at the PEP-II B-factory facility at the Stanford Linear Accelerator Center. During the summer shutdown 2002 the BaBar Event Building and Level-3 trigger farm were upgraded from 60 Sun Ultra-5 machines and 100MBit/s Ethernet to 50 Dual-CPU 1.4GHz Pentium-III systems with Gigabit Ethernet. Combined with an upgrade to Gigabit Ethernet on the source side and a major feature extraction software speedup, this pushes the performance of the BaBar event builder and L3 filter to 5.5kHz at current background levels, almost three times the original design rate of 2kHz. For our specific application the new farm provides 8.5 times the CPU power of the old system.