A high-speed front end data processor for the shower maximum detector of the CDF upgrade

A deadtimeless data acquisition system has been built to read out the 17,000 channel Shower Max System, which is part of the CDF Calorimeter. This electronics system is used to measure accurately the position of electromagnetic showers that occur in the CDF detector as a result of proton-antiproton collisions. A major component of this system is the SMXR Card, which receives and processes Shower Max information. Upon a Level 1 Accept, each VME-based read-out board receives a data stream from the front end at a rate of ~480 MB/sec. The SMXR cards process the data, which includes linearizing, adding together several time-successive samples to reconstruct slow signals, and providing fast, coarse information to the trigger system to become part of the next level (Level 2) Trigger Decision. A detailed description of the SMXR is presented, with a discussion of the preliminary operation