development of micro-pattern gaseous detectors – gem - LMU

Introduction
Our universe is momentarily described by the standard model [Grif 08]. It contains three generations
of leptons consisting of electron, muon, tau and their corresponding neutrinos and six quarks, namely
the up and down, charm and strange as well as top and bottom. They represent the fermions, spin 1
2 -
particle.
Interactions are mediated via bosons: the photon responsible of the electromagnetic interaction, the
W − , W + and Z bosons for the weak interaction and eight gluons as carrier of the strong force.
Figure 1: The LHC near Geneva and the installed experiments [CERN 10].
About 100 m deep underground in the Large Hadron Collider at CERN 1 (cf. Fig 1) near Geneva
protons collide at center-of-mass energies of up to 14 TeV to further investigate nature. A main
interest is the question of the generation of mass that is supposed to result from the Higgs mechanism.
To study the physics of these collisions, detectors are installed around the beam interaction points.
One of them is the ATLAS 2 detector, shown in Fig. 2. It is a multi purpose detector of 44 m length
and 25 m height that detects the reaction products of proton collisions designed to occur every
25 ns [ATLA 10]. The detector has a multi layer structure beginning with the inner tracking detectors
(“SCT 3 ”, “Pixel Detector” and “TRT 4 ” in Fig. 2) near the collision point and in a solenoid magnetic
1 European Organization for Nuclear Research
2 A Toroidal LHC AS
3 Semi Conductor Tracker
4 Transition Radiation Tracker
1