The Muon Trigger of the CMS experiment - design, performance, upgrade

• Druk: Warszawa, 2014
• Autor: Marcin Konecki
• Wydawca: Wydawnictwa Uniwersytetu Warszawskiego

The CMS experiment has operated smoothly during the LHC Run-1 (2010–2013). A large numer of collisions, triggered by the CMS Level-1 and High-Level trigger systems allowed CMS to discover the Higgs boson and perform many important physics measurements and searches.

In this monograph the muon trigger of the CMS detector is discussed, including its design
and performance. The CMS experiment is reviewed and its initial performance and operation are emphasized. The selected main physics results are shown. The detector upgrade perspectives are also presented.

The monograph is supplemented with the performance of the PACT trigger, development studies on muon isolation and simplified track reconstruction based on the Pixel Detector.

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• Język wydania: angielski
• ISBN: 978-83-235-1678-1
• ISBN druku: 978-83-235-1670-5
• Liczba stron: 119

1. The CMS experiment at the LHC—design and initial performance        11

1.1. Introduction        11
1.2. CMS detector        12
1.3. CMS trigger and data acquisition system        13
1.4. CMS operation        15
1.5. Commissioning and initial detector performance results        17

2. The Level-1 muon trigger. Performance        22

2.1. Level-1 trigger        22
2.1.1. Calorimeter trigger algorithms        23
2.1.2. Muon trigger        25
2.1.3. Level-1 event selection        30
2.2. Muon trigger performance        32
2.2.1. Level-1 muon trigger efficiency        32
2.2.2. Level-1 muon trigger rates        33
2.2.3. Level-1 muon trigger timing        33

3. The muon track reconstruction at the High-Level trigger        36

3.1. Introduction        36
3.2. HLT operation        36
3.3. HLT reconstruction software        39
3.4. Basics of the muon reconstruction        41
3.5. Track and primary-vertex reconstruction        43
3.5.1. Seeding and pixel-based reconstruction        43
3.5.2. Combinatorial Track Finder        45
3.6. Muon reconstruction at the HLT        47
3.6.1. Level-2 reconstruction        48
3.6.2. Level-3 reconstruction        48
3.6.3. Muon isolation        49
3.6.4. Performance        50

4. Selected physics results        53

4.1. Introduction        53
4.2. Higgs physics        53
4.2.1. H → γγ        54
4.2.2. H → ZZ → 4C        55
4.2.3. H → ττ        56
4.2.4. Combination of Higgs measurement and Higgs properties determination        58
4.3. Vector boson production, top physics and QCD        58
4.4. Other selected measurements        60
4.4.1. Charged particle multiplicities and momentum spectra        60
4.4.2. Topological correlations in two-particle distributions        61
4.4.3. Search for rare B/Bs → µ+µ− decays        62
4.5. Searches for new phenomena beyond the Standard Model        63
4.6. Heavy-ion physics with CMS        64

5. Perspective outlook and summary        65

5,1, Introduction        65
5.2. CMS upgrades during Phase-I        65
5.2.1. RPC and CSC upscope in LS1        65
5.2.2. New Level-1 trigger        66
5.2.3. HCAL modifications        66
5.2.4. Pixel Detector replacements        66
5.3. Phase-II upgrades        67
5.4. Summary of physics results        67
5.5. Summary of muon trigger operation and author’s contribution        68

A. The PACT for RPC system        69

A.1. Introduction        69
A.2. PACT system        70
A.2.1. Layout of the system        70
A.2.2. PAC algorithm        71
A.2.3. Segmentation and data flow        72
A.2.4. HSCP trigger        73
A.2.5. Commissioning challenges        75
A.3. PACT performance        75
A.4. Role of the RPC system in Level-1 muon trigger        77

B. Development of methods for track reconstruction, primary vertex finding and seed generation with the Pixel Detector        79

B.1. Introduction        79
B.2. Components of the reconstruction software        80
B.3. Estimate of track position uncertainties        81
B.3.1. Parametrization of hit errors        81
B.3.2. Parametrization of multiple scattering        81
B.3.3. Track bending in the longitudinal plane        82
B.4. Finding hit pairs        82
B.5. Finding hit triplets        85
B.6. Evaluation of the parameters of pixel-tracks        88
B.7. Pixel vertexing        89
B.8. Generation of seeds        90
B.8.1. Seeds from hit pairs        91
B.8.2. Seeds from hit triplets-91
B.9. Conclusions        91

C. Development of High-Level trigger algorithms for muon isolation        92

C.1. Introduction        92
C.2. Simulation        93
C.3. Isolation algorithm        94
C.3.1. Optimization of algorithms        95
C.3.2. Calorimeter isolation        96
C.3.3. Pixel isolation        97
C.3.4. Tracker isolation        100
C.4. Overall performance        105
C.4.1. Rate reduction        105
C.4.2. Signal efficiency        107
C.4.3. Algorithm timing        108
C.4.4. Discussion        108
C.5. Conclusions        109

D. Acronyms        110

Acknowledgements        111
Bibliography        112