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16 CHAPTER 1. INTRODUCTION The energy loss connected with this process is negligible but it is used in the detection and identification of particles (electron/pion separation, pion/proton separation and other). ˘Cerenkov counters utilize one or more of the properties of ˘Cerenkov radiation: the existence of a threshold for ˘Cerenkov radiation, the dependence of Θc on the velocity v = βc of the particle and/or the dependence of the number of emitted photons on the velocity of the particle. Transition Radiation Characteristic transition radiation is used for identifying fast electrons in Transition Radiation Detectors (TRDs; for example, see [24]). Consider a particle of charge ze crossing a boundary between vacuum and a material with a plasma frequency ωp given by Eq. 1.13. For typical radiator materials (Styrene) it is about 20 eV. The radiated energy is Etr = α z 2 γ ωp 3 . (1.19) The typical emission angle is 1/γ. Several layers of material lead to several boundaries which increases the radiated energy. The radiated energy increases with γ. Since electrons are in general the fastest particles observed in an experiment (due to their low mass), TRDs can provide electron/pion separation in the momentum range 0.5 GeV/c p 100 GeV/c [24]. Photon Interactions with Matter We distinguish three processes in which photons interact with matter: Photo Electric Effect: The interaction of the photon with the atom as a whole leads to the Photo Electric Effect. The photon is absorbed and an electron is emitted from the atom, e.g. γ + atom → atom + + e − . The cross section falls at high energies roughly as Z 5 /ω [19], where Z is the atomic charge number of the absorber material and ω is the energy of the photon. The Photo Electric Effect is important up to energies of around 100 keV (10 MeV) for materials like carbon with Z = 6 (lead with Z = 82). Compton Scattering: The interaction of the photon with a free electron leads to the Compton Effect. The photon transfers a part of its energy and momentum to the electron initially at rest, e.g.
1.2. INTERACTIONS OF PARTICLES WITH MATTER 17 γ + e → γ ′ + e ′ . The cross section is proportional to Z/ω [19]. The Compton effect is important for photon energies from about 100 eV to about 1 GeV (10 GeV) in carbon (lead). Pair Production: The interaction of the photon with the Coulomb field of the nucleus leads to the phenomenon of Pair Production, whereby the photon disappears and an electron and a positron come into existence simultaneously, e.g. γ + nucleus → e + + e − + nucleus ′ . The Feynman diagram is similar to that of bremsstrahlung, e.g. e − + nucleus → e − + γ + nucleus ′ . The cross sections of the two processes are therefore closely related 2 . The cross section for pair production is proportional to Z 2 . At high energies it becomes independent of the energy of the photon and screening of the electric field of the nucleus by the atomic electrons has to be taken into account. Then the cross section becomes [19] σpair ≈ 7 9 A NA 1 X0 . (1.20) At energies above around 100 MeV (10 MeV) for carbon (lead) this effect dominates. Hadron Interactions with Matter The strong interaction plays an important role in the detection of hadrons (p, p, n, n, π ± , K ± , K 0 ), e.g. p + nucleus → π + + π − + π 0 + ... + nucleus ′ . 2 When a high energy electron or photon is incident on a thick absorber, it initiates an electromagnetic cascade or shower, as pair production and bremsstrahlung generate more electrons and photons with lower energy. The electron energies eventually fall below the critical energy. Then they dissipate their energy by ionization and excitation rather than by the generation of more shower particles. These effects are fundamental to the operation of electromagnetic calorimeters.
Page 1 and 2: Detector Physics of Resistive Plate
Page 3 and 4: Zusammenfassung Widerstandsplattenk
Page 5 and 6: Abstract Resistive Plate Chambers (
Page 7 and 8: Contents 1 Introduction 1 1.1 Parti
Page 9 and 10: CONTENTS vii 7.2.3 Total Charge Den
Page 11 and 12: List of Figures 1.1 Schematic image
Page 13 and 14: LIST OF FIGURES xi 6.11 Simulated i
Page 15 and 16: Chapter 1 Introduction Resistive Pl
Page 17 and 18: 1.1. PARTICLE PHYSICS AND EXPERIMEN
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Page 45 and 46: 1.6. SUMMARY 31 on the Time-Of-Flig
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Page 75 and 76: 2.6. SUMMARY 61 per cluster follows
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Page 79 and 80: 3.1. THE 1-D MODEL 65 Avalanche Siz
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3.2. THE 1.5-D MODEL 67 3. The prim
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3.2. THE 1.5-D MODEL 69 Here l(z
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3.2. THE 1.5-D MODEL 71 charge [pC]
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3.2. THE 1.5-D MODEL 73 a) b) induc
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3.2. THE 1.5-D MODEL 75 number of c
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3.3. THE 2-D MODEL 77 where δt is
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3.3. THE 2-D MODEL 79 Er(r, z, r
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3.3. THE 2-D MODEL 81 y r E Er θ x
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3.4. THE 3-D MODEL 83 The charge in
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3.4. THE 3-D MODEL 85 Electrons a)
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Chapter 4 Geometries and Typical Op
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RPC gas q [mm] g [mm] εr EW [/mm]
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The values shown in Table 4.3 are r
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Chapter 5 Results Obtained with the
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5.1. EFFICIENCY AND TIME RESOLUTION
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5.2. CHARGE-TO-TIME CORRELATION 97
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6.1. SIGNAL RISE TIME 101 induced c
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6.2. CHARGE SPECTRA 103 counts 10 3
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6.2. CHARGE SPECTRA 105 charges/ste
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6.2. CHARGE SPECTRA 107 The differe
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6.2. CHARGE SPECTRA 109 counts/35fC
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6.2. CHARGE SPECTRA 111 charges/ste
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6.3. OPERATIONAL MODE OF RPCS 113 t
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6.4. CHARGE-TO-TIME CORRELATION 115
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6.5. AVALANCHES IN PURE ISOBUTANE 1
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6.6. STREAMERS 121 a) b) electrons
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7.1. COMPARISON OF THE DIFFERENT MO
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7.2. AVALANCHES IN C2F4H2/ I-C4H10/
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7.4. SUMMARY 151 (e) The total elec
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7.4. SUMMARY 153 contracted at thei
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Chapter 8 Conclusions and Outlook C
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Appendix A Differential Collision C
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A.4. SCATTERING OF MASSIVE SPIN 1 P
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Appendix B Überblick Widerstandspl
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B.1. MOTIVATION FÜR DIE ARBEIT 163
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B.2. DETEKTORPHYSIK VON RPCS 165 i(
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B.4. SCHLUSSFOLGERUNG UND AUSBLICK
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Bibliography [1] W. Riegler, R. Vee
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BIBLIOGRAPHY 171 [29] V. Parchomchu
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BIBLIOGRAPHY 173 [59] E. Keil. The
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BIBLIOGRAPHY 175 [88] P. Fonte. App
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Danksagung Während der Dissertatio
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Curriculum Vitae Persönliche Infor
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