Table Of ContentLecture Notes in Physics
Kazunori Hanagaki
Junichi Tanaka
Makoto Tomoto
Yuji Yamazaki
Experimental
Techniques in
Modern High-
Energy Physics
A Beginner’s Guide
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Kazunori Hanagaki · Junichi Tanaka ·
Makoto Tomoto · Yuji Yamazaki
Experimental Techniques
in Modern High-Energy
Physics
A Beginner‘s Guide
KazunoriHanagaki JunichiTanaka
InstituteofParticleandNuclearStudies InternationalCenterforElementaryParticle
KEK Physics
Ibaraki,Japan TheUniversityofTokyo
Tokyo,Japan
MakotoTomoto
InstituteofParticleandNuclearStudies YujiYamazaki
KEK DepartmentofPhysics
Ibaraki,Japan KobeUniversity
Kobe,Japan
DepartmentofPhysics
NagoyaUniversity
Nagoya,Japan
ThisworkwassupportedbySponsoringConsortiumforOpenAccessPublishinginParticle
Physics.
ISSN0075-8450 ISSN1616-6361 (electronic)
LectureNotesinPhysics
ISBN978-4-431-56929-9 ISBN978-4-431-56931-2 (eBook)
https://doi.org/10.1007/978-4-431-56931-2
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Preface
This book is meant to be a practical introduction to data analysis in high-
energy physics experiments, especially collider experiments using high-energy
accelerators.
The field requires a very wide range of knowledge, not only for the theoretical
particle physics but also for the detector technology and computing science. We
often find beginners in this field suffering from understanding how data analysis
is taking place, simply because of too many things one needs to know. Reading
journalpapersoftendoesnothelpsincecomprehensiveunderstandingandtraining
are required, which are not described in the papers themselves. It is quite difficult
to obtain such skills unless you do once a data analysis by yourself. We hope that
this book helps reduce such difficulties by providing a one-stop “explanation” on
key aspects of data analysis.
This book should also serve as an introductory textbook for those who are
learning about individual subjects in data analysis, such as
•
Basic idea on methods to reconstruct and identify particles;
•
Detector calibration in collider experiments;
•
Statistical methods used in collider experiments;
•
Methods to increase sensitivities of an experiment through data analysis
techniques;
•
Simulation of particle collisions and detector responses.
This book is intended for undergraduate and first-year graduate students who
have taken basic-level courses in particle physics. Throughout the book, we tried
toexplainwhathappenswithoutexplicitlyusingmanyequations.Weneithercover
theformalismontheinteractionofparticlesinmatternorthetheoryoftheparticle
v
vi Preface
physics Standard Model. Instead, we, experimental physicists, provide a “prac-
tical” explanation of how to understand after considering those formalism and
theories.
Tsukuba, Japan Kazunori Hanagaki
Tokyo, Japan Junichi Tanaka
Nagoya/Tsukuba, Japan Makoto Tomoto
Kobe, Japan Yuji Yamazaki
October 2021
Acknowledgments
We thank Springer for giving us a chance to publish this book. We greatly appre-
ciateSpringer’seditorsfortheirpatience.Thestartofwritingthisbookisbackin
2015whenparticlephysicistsbaskedintheafterglowofthediscoveryoftheHiggs
boson. Since then our writing was so slow, but the editors kept us encouraging to
go on. Without their endless efforts, this book would not be realised.
Wethankourfamiliesfortheircontinuoussupportnotonlyinwritingthisbook
but also the physicists’ life.
Tsukuba, Japan Kazunori Hanagaki
Tokyo, Japan Junichi Tanaka
Nagoya/Tsukuba, Japan Makoto Tomoto
Kobe, Japan Yuji Yamazaki
October 2021
vii
Contents
1 Introduction ......................................................... 1
2 BasicIdeaofMeasurementsinParticleCollisions ................... 7
2.1 Observables of Particle Scattering ............................... 7
2.2 Cross Section and Luminosity ................................... 9
2.3 Identifying Processes Through Measurements of Final State
Particles ......................................................... 11
2.4 Event Acceptance and Efficiency ................................ 14
2.5 Nature of Hadron-Hadron Collisions and Kinematic Variables .... 15
2.6 Structure of Hadrons and Parton Density Function ............... 18
References ........................................................... 20
3 Apparatus ........................................................... 21
3.1 Particle Collisions at High Energies .............................. 21
3.2 Accelerator ...................................................... 22
3.3 Detector ......................................................... 24
3.3.1 Particle Interaction with Material ......................... 25
3.3.2 ATLAS Detector ......................................... 26
3.3.3 Trigger ................................................... 29
3.3.4 Optimisation of Detector Performance .................... 34
References ........................................................... 34
4 Statistics ............................................................. 35
4.1 Uncertainty ..................................................... 36
4.1.1 Statistical Uncertainty .................................... 36
4.1.2 Systematic Uncertainty ................................... 36
4.2 Probability Distribution .......................................... 37
4.2.1 Basics of Probability Distributions ........................ 38
4.2.2 Binomial Distribution .................................... 39
4.2.3 Poisson Distribution ...................................... 40
4.2.4 Normal Distribution (Gaussian Distribution) .............. 41
4.2.5 Uniform Distribution ..................................... 42
4.2.6 Breit-Wigner Distribution ................................ 44
ix
x Contents
4.2.7 Exponential Distribution .................................. 44
4.2.8 χ2 (Chi-Square) Distribution ............................. 45
4.3 Error Propagation ............................................... 45
4.4 Maximum Likelihood Method ................................... 47
4.5 Least Squares Method ........................................... 49
4.6 Statistical Figure of Merit ....................................... 49
4.7 Hypothesis Test ................................................. 49
4.7.1 Discovery and Exclusion ................................. 50
4.7.2 Profile Likelihood Fit .................................... 52
4.7.3 Profile Likelihood Ratio .................................. 53
References ........................................................... 57
5 DetectorCalibration ................................................. 59
5.1 From Raw Data to Meaningful Information ...................... 59
5.2 Detector Alignment ............................................. 60
5.3 Momentum Scale Calibration of Magnetic Spectrometer .......... 61
5.3.1 Momentum Measurement and its Resolution .............. 62
5.3.2 Momentum Scale Calibration ............................. 63
5.4 Energy Calibration of Calorimeter ............................... 64
5.4.1 Cell-by-Cell Calibration .................................. 64
5.4.2 Energy Cluster Calibration of Electromagnetic Shower .... 65
5.4.3 Energy Cluster Calibration of Hadronic Shower ........... 67
References ........................................................... 68
6 ParticleIdentification ................................................ 69
6.1 Tracking and Vertexing .......................................... 69
6.1.1 Space Hit Point .......................................... 70
6.1.2 Track Finding ............................................ 73
6.1.3 Track Fitting ............................................. 76
6.1.4 Vertex Finding ........................................... 77
6.2 Electron and Photon ............................................. 79
6.2.1 Interactions with Materials ............................... 79
6.2.2 Reconstruction ........................................... 81
6.2.3 Identification ............................................. 82
6.3 Muon ........................................................... 87
6.3.1 Muon Momentum Measurement .......................... 87
6.3.2 Examples of Muon Detectors ............................. 89
6.3.3 Muon Reconstruction ..................................... 95
6.3.4 Muon Identification ...................................... 96
6.3.5 Muon Isolation ........................................... 97
6.3.6 Momentum Scale and Resolution ......................... 97
6.4 Jet Identification ................................................. 99
6.4.1 Fragmentation: Partons to Particles ....................... 99
