Kevin Lannon

Search for New Phenomena in the CDF Top Quark Sample

We present recent results from CDF in the search for new phenomena appearing in the top quark samples. These results use data from p{bar p} collisions at {radical}s = 1.96 TeV corresponding to an integrated luminosity ranging from 195 pb{sup -1} to 760 pb{sup -1}. No deviations are observed from the Standard Model expectations, so upper limits on the size of possible new phenomena are set.

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.

The CDF II Level 1 Track Trigger Upgrade

The CDF II detector uses dedicated hardware to identify charged tracks that are used in an important class of level 1 trigger decisions. Until now, this hardware identified track segments based on patterns of hits on only the axial sense wires in the tracking chamber and determined the transverse momentum of track candidates from patterns of track segments. This identification is efficient but produces trigger rates that grow rapidly with increasing instantaneous luminosity. High trigger rates are a consequence of the large numbers of low momentum tracks produced in inelastic collisions which generate overlapping patterns of hits that match those expected for high-momentum tracks. A recently completed upgrade to the level 1 track trigger system makes use of information from stereo wires in the tracking chamber to reduce the rate of false triggers while maintaining high efficiency for real high momentum particles. We describe the new electronics used to instrument the additional sense wires, identify track segments and correlate these with the track candidates found by the original track trigger system. The performance of this system is characterized in terms of the efficiency for identifying charged particles and the improved rejection of axial track candidates that do not correspond to real particles.

Upgrade of the XFT trigger for CDF

The CDF Detector at the Tevatron currently uses an online track trigger, known as the XFT, to identify charged tracks with P/sub T/ > 1.5 GeV/c which are then utilized in a number of ways to produce an event-by-event trigger decision. The tracks found by the XFT are utilized in approximately 80 percent of the physics triggers, including identification of high energy leptons (e, /spl mu/, /spl tau/), events containing heavy, flavor (c, b, t) and events with interesting topologies in for searches for new phenomena. The XFT is functioning well in the current system. As the Tevatron luminosity grows, occupancy in the tracking chamber increases from multiple proton-antiproton interactions. In the trigger, this additional occupancy will cause the tracking resolution to degrade and the rate of fake tracks to grow. We propose to upgrade the existing system to mitigate these effects and allow the CDF detector to operate at its fullest capacity at the highest possible luminosity.