Measurement of the Z boson cross-section in - Harvard University ...

Chapter 2: The Accelerator and the Experiment 59
pT resolution of the barrel 7 . TGCs have the required high rate capability as well as
good time resolution. They cover the region 1.05 < |η| < 2.7, although signal from
beyond |η| =2.4 is not used for triggering. The TGCs are arranged in four wheels in
each endcap, one before the endcap toroid, and three after the toroid (Figure 2.12).
Only the three wheels after the toroid are used for triggering.
Figure 2.12: Schematic of the ATLAS muon trigger system. The triggering schemes
for high-pT and low-pT tracks are indicated.
TGCs are multiwire proportional chambers, with the anode-cathode distance
7 For example, at |η| =2.4, the momentum of a track is 5.8×pT , while the integrated bending
power 8 of the magnetic field is only about twice that at |η| = 0 [98].