The CDF II 3D-Track Level 2 Trigger Upgrade

The CDF II Level 1 track trigger system reconstructs charged tracks in the plane transverse to the beam direction. The track trigger electronics uses the hit data from the 4 axial layers of the CDF II central outer tracking chamber, and has been recently upgraded to include the complementary information from the 3 stereo layers. Together with the existing system it provides improved fake track rejection at Level 1. In addition, the high resolution segment information is delivered to the Level 2 processors, where software algorithms perform three-dimensional stereo track reconstruction. The 3D-tracks are further extrapolated to the electromagnetic calorimeter towers and muon chambers to generate trigger electron and muon candidates. The invariant mass of track pairs and track isolations are also calculated and used in the Level 2 trigger decision. We describe the hardware and software for the Level 2 part of the track trigger upgrade as well as the performance of the new track trigger algorithms.