: Oliver Pooth
: The CMS Silicon Strip Tracker Concept, Production and Commissioning
: Vieweg+Teubner (GWV)
: 9783834896391
: 1
: CHF 47.50
:
: Allgemeines, Lexika
: English
: 147
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Oliver Pooth describes the silicon strip tracker of the CMS detector and discusses methods of quality control that are new to the field of particle detector physics. These methods were established to guarantee a uniform behaviour of all detector modules which were built and tested in various places worldwide.

Dr. Oliver Pooth completed his postdoctoral lecture qualification at the RWTH Aachen University. He is a member of the CMS collaboration and now works as a private lecturer at the 3rd Physics Institute B at the RWTH Aachen University.
Semiconductor Detectors (p. 21-22)

Particle detectors based on semiconducting materials are used in a wide range of applications in various physics ?elds. The two main applications are tracking of charged particles and the precise energy spectroscopy of photons. Since the 1950s p-n junctions are used to detect signals from charged particles and photons traversing the depletion zone between an n-doped and p-doped material. For 25 years in coincidence with the detection of short lived mesons containing charm and bottom quarks and the study of decaying tau leptons, the particle physics community developed great interest in very fast particle detectors with high resolution. First applications of semiconducting particle detectors in high energy physics experiments date back to the 1970s.

Today nearly every large scale high energy physics experiment makes use of silicon strip and/or silicon pixel detectors to precisely determine the trajectories of traversing charged particles. The tracking device of the CMS experiment with a sensitive silicon area of approximately 200m2 is the largest project of this type today. The principle of operation of semiconductor detectors is similar to an ionisation chamber but is based on solid state material. Compared to the low density of the counting gas in gaseous detectors, semiconductor detectors are able to measure particles with higher material densities. In tracking applications the segmentation of electrodes allows a ?ner separation of the detection cells and therefore higher spatial resolution compared to gaseous detectors.

Charged particles or photons create electron hole pairs in the semiconductor material. Inside an electric ?eld the produced charge carriers are collected and converted to an electric signal that can be ampli?ed and shaped into the appropriate needs. Compared to the counting gas in gaseous detectors the average energy necessary to produce an electron hole pair in a semiconductor is one order of magnitude smaller (2.8 eV for germanium, 3.6 eV for silicon).

Because of the small energy gap between valence band and conduction band (0.67 eV for germanium, 1.14 eV for silizium) the detectors are often operated below room temperature to reduce the effect of thermal noise. Basic properties of silicon are summarised in table 2.1. As the amount of energy required to create an electron-hole pair is known, and is independent of the energy of the incident radiation, measuring the number of electron-hole pairs allows the determination of the energy of incident photons.

Energy spectroscopy is therefore possible using semiconductor detectors with excellent energy resolution compared to gaseous devices. Furthermore diamond based detectors [19] are an alternative to silicon detectors and are expected to offer better radiation hardness compared to silicon detectors. But today they are much more expensive and more dif?cult to produce even on a small scale.
Preface7
Contents9
List of Figures10
List of Tables14
1 Introduction15
1.1 The LHC project15
1.2 The LHC physics programme20
1.3 The CMS experiment22
1.3.1 The muon spectrometer26
1.3.2 The magnet28
1.3.3 The calorimeter system28
1.3.4 The inner tracking system30
1.3.5 The trigger system32
2 Semiconductor Detectors34
2.1 The p-n junction36
2.2 Signal creation40
2.2.1 Detector types42
2.3 Radiation effects49
3 The CMS Silicon Strip Tracker51
3.1 Tracker concept51
3.1.1 Layout of the silicon tracker54
3.2 Silicon strip detector modules56
3.2.1 CMS Silicon Sensor56
3.2.2 Mechanics59
3.2.3 Readout Hybrids63
3.3 Readout, triggering and services65
3.3.1 On-detector module readout electronics67
3.3.1.1 The APV25-S1 readout chip67
3.3.1.2 The multiplexer chip, APVMUX71
3.3.1.3 The Tracker Phase Locked Loop chip, TPLL71
3.3.1.4 The Detector Control Unit chip, DCU72
3.3.2 Off-detector module readout electronics73
3.3.2.1 Optical links73
3.3.2.2 The front-end driver74
3.3.2.3 Services75
3.3.2.4 Slow control and triggering76
3.3.2.5 Summary77
3.4 Radiation hardness78
3.5 Tracker substructures79
3.5.1 Tracker Inner Barrel and Tracker Inner Disks80
3.5.2 Tracker Outer Barrel82
3.5.3 Tracker End Caps85
3.6 Laser Alignment System92
3.7 Cooling system93
3.8 Material budget94
3.9 Expected performance95
4 Detector Production and Commissioning99
4.1 Production99
4.1.1 Module production102
4.1.1.1 Quality control during production105
4.1.1.2 Summary of TEC module production115
4.1.2 Petal production118
4.1.3 Substructures122
4.1.3.1 TIB/TID124
4.1.3.2 TOB126
4.1.3.3 TEC127
4.2 Commissioning experiences128
4.2.1 Magnet test and cosmic challenge129
4.2.2 Tracker slice test133
5 Conclusion141
Bibliography142