L. Babukhadia

tt̄ production cross section in pp̄ collisions at √s = 1.8 TeV

Results are presented on a measurement of the t (t) over bar pair production cross section in p (p) over bar collisions at roots=1.8 TeV from nine independent decay channels. The data were collected by the D empty set experiment during the 1992-1996 run of the Fermilab Tevatron Collider. A total of 80 candidate events is observed with an expected background of 38.8+/-3.3 events. For a top quark mass of 172.1 GeV/c(2), the measured cross section is 5.69+/-1.21(stat)+/-1.04(syst) pb.Results are presented on a measurement of the ttbar pair production cross section in ppbar collisions at sqrt{s} = 1.8 TeV from nine independent decay channels. The data were collected by the Dzero experiment during the 1992-1996 run of the Fermilab Tevatron Collider. A total of 80 candidate events are observed with an expected background of 38.8 +- 3.3 events. For a top quark mass of 172.1 GeV/c^2, the measured cross section is 5.69 +- 1.21 (stat) +- 1.04 (sys) pb.

First results from the central tracking trigger of the DO experiment

An overview of the DO Central Track Trigger (CTT) for the Tevatron Run 2 program is presented. This newly commissioned system uses information from the DO Central Fiber Tracker and Preshower Detectors to generate trigger information for the first level of the three-tiered DO Trigger. The system delivers tracking detector trigger decisions every 132 ns, based on input data flowing at a rate of 475 Gbit per second. Initial results indicate excellent performance of the CTT. First studies of efficiency and trigger performance of the CTT are presented.

Performance Measurement of the Upgraded DØ Central Track Trigger

The DOslash 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 times 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 > 1.5 GeV 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.

The central track trigger of the DO experiment

The general purpose DO collider detector, located at Fermi National Accelerator Laboratory is operated in the high luminosity (L = 2 /spl times/ 10/sup 32/cm/sup -2/s/sup -1/) and high collision rate environment (396 ns between beam crossings) of the upgraded Tevatron proton anti-proton accelerator. DO uses a three tiered trigger system to select events for offline storage and analysis. This talk describes the architecture and performance of the DO central track trigger (CTT) system based on the new Central Fiber Tracker. Central Preshower and Forward Preshower detectors, with emphasis on the interface to and integration with the second tier L2 Trigger system.