doctoral thesis

26 CHAPTER 1. INTRODUCTION
Cleaning I
ALICE
3
2
TI 2
PMI 23
4
BA6
PM18
RF
ATLAS
1
Injections
SPS
BA4
TI 8
5
8
CMS
7
6
LHC-B
Dump
Cleaning II
Figure 1.8: A view of the Large Hadron Collider (LHC) and the four LHC experiments
[59]. The LHC will be housed in the old LEP tunnel that has 26.659 m circumference.
The two general purpose experiments, ATLAS and CMS, are diametrically opposite
in Pits 1 and 5, respectively. The heavy ion experiment ALICE will be in Pit 2. The
LHCb experiment is dedicated to the study of CP violation and other rare phenomena
in the decay of Beauty particles and is situated in Pit 8.
of 25 ns sets the scale for the required time resolution of the detectors. To be able to
reliably tell for each muon from which collision it originates and to limit random coincidences
from background hits, the trigger detectors have to reach a time resolution
around 1 ns, which can easily be achieved with RPCs. The tracks of the muons are
measured by other detectors in the ATLAS muon system, because here a high position
resolution is required. One utilizes drift tubes and cathode strip chambers. Together
with the toroidal magnet they form the muon spectrometer which makes possible the
measurement of the muon momenta.
We will refer to the type of RPC used for triggering in the muon detector systems
as the Trigger RPC from now on. A schematic image of a single gap Trigger
RPC is shown in Fig. 1.11. A commonly used gas mixture is C2F4H2/ i-C4H10/ SF6
(96.7%, 3%, 0.3%). The operating voltage of 10 kV results in an electric field of