Performance Measurement of the Upgraded DØ Central Track Trigger

The DØ experiment was upgraded in spring 2006 to harvest the full physics potential of the Tevatron accelerator at Fermi National Accelerator Laboratory, Batavia, Illinois, USA. It is expected that the peak luminosity delivered by the accelerator will increase to over 300×1030 cm�2s�1. One of the upgraded systems is the Central Track Trigger (CTT). The CTT uses the Central Fiber Tracker (CFT) and Preshower detectors to identify central tracks with pT > 1.5GeV at the first trigger level. Track candidates are formed by comparing fiber hits to predefined track equations. In order to minimize latency, this operation is performed in parallel using combinatorial logic implemented in FPGAs. Limited hardware resources prevented the use of the full granularity of the CFT. This leads to a high fake track rate as the occupancy increases. In order to mitigate the problem, new track- finding hardware was designed and commissioned. We report on the upgrade and the improved performance of the CTT system.