The use of content addressable memories in the level 2 trigger for the CLAS detector at CEBAF

The LEVEL 2 trigger in the CLAS detector will find tracks and associate a momentum and angle with each track within 2 ps after the event. This is done through a hierarchical track finding design in which track segments ae found in each dnft chamber axial superlayer. An m y of 384 custom content addressable (or associative) memories (CAMS) uses independent subfield matchng to link these track segments into roads. The track parameters corresponding to each found road are then looked up in a separate memory. We present the overall architecture of the LEVEL 2 trigger, the details of how the CAM chip links tracks segments to find roads, and report on the performance of our prototype CAM chips.