development of micro-pattern gaseous detectors – gem - LMU

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58 Chapter 5 Efficiency Determination photomultiplier scintillator 1 GEM scintillator scintillator 22 photomultiplier photomultiplier z Sc 2 GEM MC Simulation θ ϕ Sc 1 Figure 5.1: Schematics of the defined layers for simulation. Normalizing this vector with respect to the z-axis defines the vector check[i] and i ∈ [0, 1, 2] : check[i] = direc[i] direc[2] Starting with the detection point posz at the lower scintillator, the check-vector is extrapolated to the upper scintillators lower and upper surfaces, respectively. If the endpoint of the track lays within the respective rectangle (see Fig. 5.2), the muon has crossed also the upper scintillator and will be tagged as an ”upper scintillator hit”. The same method can be applied to checking if this muon also hit the GEM detector. Then it is tagged as a ”GEM hit” muon. Figure 5.2: Cross section of the simulation model. The starting point of muons is on the lower scintillator Sc1. Running this procedure for a large number of simulated events and taking the ratio of “GEM hits” over “upper scintillator hits”, one receives the geometrical correction factor fcorr that has to be inserted in the efficiency calculation: Sc 2 GEM Sc 1 ϕ x (5.3)
5.2. Measurement with Unsegmented Anode 59 εcorr = Ndetected particles Ntotal particles · fcorr Assuming an alignment of the two scintillators (cf. Fig. A.1 and Fig. A.2 within ±5 mm, the simulation yields for the correction factor of the efficiency a value of (5.4) fcorr = 0.868 ± 0.005 . (5.5) In the following discussion this correction factor is considered when talking about efficiency. 5.2 Measurement with Unsegmented Anode After construction and commissioning of the prototype 1.0, the first measurements of cosmic muons began in March 2010 with an unsegmented copper anode and readout by the CATSA preamplifier. As mentioned in Ch. 3.1.1 the GEM foils were conditioned to HV of ∆UGEM around 300V see Tab. 5.1. corr ∈ 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 GEM foil number 1 2 3 Applicable ∆UGEMi [V] 330 V 290 V 340 V Table 5.1: Voltage rigidity of the GEM foils in the prototype 1.0 with unsegmented anode. Δ U = 340 V GEM3 Δ U = 290 V GEM2 Δ U = 330 V GEM1 EffGEM vs Edrift cm V Etrans1,2 = 1333 cm V Eind = 1333 0 0.7 0.8 0.9 1 1.1 1.2 1.3 Edrift [kV/cm] Figure 5.3: Efficiency as a function of the drift field Edri ft. corr ∈ 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Δ U = 340 V GEM3 Δ U = 290 V GEM2 Δ U = 330 V GEM1 EffGEM vs Etrans1,2 cm V Edrift = 1025 Eind = Etrans1,2 0 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Etrans1,2 [kV/cm] Figure 5.4: Efficiency as a function of increasing transfer and induction field Etrans1,2 = Eind. Results of the first studies in March are shown in Fig. 5.3 and Fig. 5.4. Every data point represents a sample of Nsample = 2000 cosmic muon events. The statistical error is given by: ∆stat.ε = ε · (1 − ε) Nsample (5.6)
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DEVELOPMENT OF MICRO-PATTERN GASEOU
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Dedicated to Engin Abat 29/09/1979
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Contents Introduction I 1 Interacti
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Introduction Our universe is moment
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is testing tubes with alternative d
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efficiency. Monitoring of this para
Page 18 and 19: 8 Chapter 1 Interactions of Charged
Page 20 and 21: 10 Chapter 1 Interactions of Charge
Page 32 and 33: 22 Chapter 2 The GEM Principle doub
Page 34 and 35: 24 Chapter 2 The GEM Principle mobi
Page 36 and 37: 26 Chapter 2 The GEM Principle
Page 38 and 39: 28 Chapter 3 The Triple GEM Prototy
Page 50 and 51: 40 Chapter 4 Energy Resolution and
Page 70 and 71: 60 Chapter 5 Efficiency Determinati
Page 76 and 77: 66 Chapter 6 Rise Time Studies 3000
Page 78 and 79: 68 Chapter 6 Rise Time Studies 2 ns
Page 80 and 81: 70 Chapter 6 Rise Time Studies obse
Page 82 and 83: 72 Chapter 6 Rise Time Studies
Page 84 and 85: 74 Chapter 7 Gas Gain Studies eff G
Page 86 and 87: 76 Chapter 7 Gas Gain Studies
Page 88 and 89: 78 Chapter 8 Implementation of High
Page 98 and 99: 88 Chapter 9 Summary and Outlook st
Page 100 and 101: 90 BIBLIOGRAPHY [Bieb 03] O. Biebel
Page 102 and 103: 92 BIBLIOGRAPHY [NIST 10] NIST. “
Page 104 and 105: 94 BIBLIOGRAPHY
Page 106 and 107: 96 Chapter A Assumptions for Effici
Page 108 and 109: 98 Chapter B Construction Drawings
Page 114 and 115: 104 Chapter C Design of Prototype 2
Page 116 and 117: 106 Chapter C Design of Prototype 2
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108 Chapter C Design of Prototype 2
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Acknowledgements First of all I wou
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Selbständigkeitserklärung Ich ver
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