Electronics for the BaBar central drift chamber

The central drift chamber for the BaBar detector at the SLAG B-factory is b ased on a hexagonal cell design with 7104 cells arranged in 40 layers and d rift gas Helium:isobutane (80%:20%). Performance optimization and integrati on requirements led to an electronics design that mounts the amplifier-disc riminator and digitizing circuitry directly on the endplate. High channel d ensity is achieved using a 4-channel custom amplifier-discriminator IC and an 8-channel custom CMOS TDC/FADC IC on a single circuit board. Data read f rom the front ends are multiplexed on 4 fiber optic links, and prompt trigg er data are sent out continuously on 24 links. Analysis of cosmic ray data demonstrates that the electronics design meets the performance goals for th e BaBar drift chamber. The final electronics were installed on the drift ch amber in July, 1998. Installation of BaBar on beamline is scheduled for Mar ch, 1999.