Pooth The CMS Silicon Strip Tracker

Concept, Production and Commissioning
2010
ISBN: 978-3-8348-9639-1
Verlag: Vieweg & Teubner
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 147 Seiten, eBook

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.

Zielgruppe

Research

Autoren/Hrsg.

Pooth, Oliver

Inhaltsverzeichnis

1;Preface;7
2;Contents;9
3;List of Figures;10
4;List of Tables;14
5;1 Introduction;15
5.1;1.1 The LHC project;15
5.2;1.2 The LHC physics programme;20
5.3;1.3 The CMS experiment;22
5.3.1;1.3.1 The muon spectrometer;26
5.3.2;1.3.2 The magnet;28
5.3.3;1.3.3 The calorimeter system;28
5.3.4;1.3.4 The inner tracking system;30
5.3.5;1.3.5 The trigger system;32
6;2 Semiconductor Detectors;34
6.1;2.1 The p-n junction;36
6.2;2.2 Signal creation;40
6.2.1;2.2.1 Detector types;42
6.3;2.3 Radiation effects;49
7;3 The CMS Silicon Strip Tracker;51
7.1;3.1 Tracker concept;51
7.1.1;3.1.1 Layout of the silicon tracker;54
7.2;3.2 Silicon strip detector modules;56
7.2.1;3.2.1 CMS Silicon Sensor;56
7.2.2;3.2.2 Mechanics;59
7.2.3;3.2.3 Readout Hybrids;63
7.3;3.3 Readout, triggering and services;65
7.3.1;3.3.1 On-detector module readout electronics;67
7.3.1.1;3.3.1.1 The APV25-S1 readout chip;67
7.3.1.2;3.3.1.2 The multiplexer chip, APVMUX;71
7.3.1.3;3.3.1.3 The Tracker Phase Locked Loop chip, TPLL;71
7.3.1.4;3.3.1.4 The Detector Control Unit chip, DCU;72
7.3.2;3.3.2 Off-detector module readout electronics;73
7.3.2.1;3.3.2.1 Optical links;73
7.3.2.2;3.3.2.2 The front-end driver;74
7.3.2.3;3.3.2.3 Services;75
7.3.2.4;3.3.2.4 Slow control and triggering;76
7.3.2.5;3.3.2.5 Summary;77
7.4;3.4 Radiation hardness;78
7.5;3.5 Tracker substructures;79
7.5.1;3.5.1 Tracker Inner Barrel and Tracker Inner Disks;80
7.5.2;3.5.2 Tracker Outer Barrel;82
7.5.3;3.5.3 Tracker End Caps;85
7.6;3.6 Laser Alignment System;92
7.7;3.7 Cooling system;93
7.8;3.8 Material budget;94
7.9;3.9 Expected performance;95
8;4 Detector Production and Commissioning;99
8.1;4.1 Production;99
8.1.1;4.1.1 Module production;102
8.1.1.1;4.1.1.1 Quality control during production;105
8.1.1.2;4.1.1.2 Summary of TEC module production;115
8.1.2;4.1.2 Petal production;118
8.1.3;4.1.3 Substructures;122
8.1.3.1;4.1.3.1 TIB/TID;124
8.1.3.2;4.1.3.2 TOB;126
8.1.3.3;4.1.3.3 TEC;127
8.2;4.2 Commissioning experiences;128
8.2.1;4.2.1 Magnet test and cosmic challenge;129
8.2.2;4.2.2 Tracker slice test;133
9;5 Conclusion;141
10;Bibliography;142

Semiconductor Detectors.- The CMS Silicon Strip Tracker.- Detector Production and Commissioning.- Conclusion.

Leseproben

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.

Über Autor(innen)

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.