12 Triggering and High-Level Data Selection
543
Fig. 12.6 Organization of the ATLAS jet trigger system
refines the muon trigger with a sharper momentum threshold that is not affected
by the backgrounds in the muon chambers. It also can be used to identify heavy
flavour candidates. Both Tevatron experiments CDF and DØ employed level-1
tracking triggers. CDF used signals from the Central Outer Tracker (COT) opencell drift chamber in the eXtremely Fast Tracker (XFT) to perform charged track
reconstruction in the r–φ plane for the L1T [4]. Track segments were found by
comparing hit patterns in a COT superlayer to a list of valid patterns or “masks”.
These masks contained specific patterns of prompt and delayed hits on the 12 wire
layers of an axial COT superlayer. Tracks were found by comparing track segment
patterns in all four layers to a list of valid segment patterns or “roads”. The XFT had
an efficiency >90% for tracks with p T > 1.5 GeV/c, transverse momentum resolution
of δp T /p T = 0.002 p T and pointing resolution of δφ = 0.002 radians with respect to
the beam line [5]. The XFT reported the highest p T track in each of 288 azimuthal
543
Fig. 12.6 Organization of the ATLAS jet trigger system
refines the muon trigger with a sharper momentum threshold that is not affected
by the backgrounds in the muon chambers. It also can be used to identify heavy
flavour candidates. Both Tevatron experiments CDF and DØ employed level-1
tracking triggers. CDF used signals from the Central Outer Tracker (COT) opencell drift chamber in the eXtremely Fast Tracker (XFT) to perform charged track
reconstruction in the r–φ plane for the L1T [4]. Track segments were found by
comparing hit patterns in a COT superlayer to a list of valid patterns or “masks”.
These masks contained specific patterns of prompt and delayed hits on the 12 wire
layers of an axial COT superlayer. Tracks were found by comparing track segment
patterns in all four layers to a list of valid segment patterns or “roads”. The XFT had
an efficiency >90% for tracks with p T > 1.5 GeV/c, transverse momentum resolution
of δp T /p T = 0.002 p T and pointing resolution of δφ = 0.002 radians with respect to
the beam line [5]. The XFT reported the highest p T track in each of 288 azimuthal