development of micro-pattern gaseous detectors – gem - LMU

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52 Chapter 4 Energy Resolution and Pulse Height Analysis observes a greater pulse height for all three configuration at Edri ft = 1.25 kV/cm. This is followed by a slight decrease going to higher drift fields. One assumes that this may be due to electric field lines ending on the upper electrode of GEM3 preventing them from being amplified in the GEM foils. pulse height [0.244 mV] 22 20 18 16 14 12 10 8 6 4 Cosmics Pulse Height vs E drift Δ UGEM3 = 330 V Δ UGEM2 = 290 V Δ UGEM1 = 320 V Cu anode unseg preamp: CATSA82 Ar:CO2 93:7 @ 1 bar cm kV Etrans1,2 = Eind = 1.30 cm kV Etrans1,2 = Eind = 1.70 cm kV Etrans1,2 = Eind = 2.00 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Edrift[kV/cm] Figure 4.19: MPV of the Landau spectra as a function of Edri ft at constant Etrans1,2 = Eind This may be just a part of the answer since the physical processes in a triple GEM detector are very complicated [Buzu 02]. Nevertheless, these effects result only in a small variation of 5% in the pulse height concerning measurements at constant Eind = Etrans1,2 = 1.7 kV/cm. 4.5 Pulse Height Dependence on Strip Readout The five-fold segmented anode was used to study the influence of strip size on the pulse height of the anode signals. Five data points were taken when one, two, three, four and all five strips were readout by one preamplifier. The dimension of a single readout strip is shown in Fig. 4.20. We used the 55 Fe source located at the central position and recorded data samples with all three preamplifiers. The readout copper strips of the five-fold segmented anode were coupled together while open strips were connected with a resistor of 100 Ω to ground as shown in Fig. 4.20. Fig. 4.21 repeats schematically the capacities and charge flows necessary for the following calculations. Foremost, data samples with 40000 events taken with the CATSA82 preamplifier can bee seen in Fig. 4.22. For comparison, the operation parameters were chosen to be identical to a setup with unsegmented anode (round data point in Fig. 4.22). The pulse height is decreasing as more strips are readout being coupled together. This results in a 50% smaller peak for five stripr being read out compared to only one strip-readout. The unsegmented anode shows the lowest pulse height of the 55 Fe spectrum. One observes for all preamplifiers a decreasing pulse height with increasing strip number, see Fig. 4.23. This plot shows measurements at identical operation parameters recorded once with the Canberra preamplifier and repeated with the ELab version. The detected charge Qtot flows from the anode (Cdet) to the coupling capacitor Ccoup. At equilibrium the voltage on Cdet and Ccoup is identical:
4.5. Pulse Height Dependence on Strip Readout 53 100 mm 100 mm 100 Ω 1 mm 10 mm 20 mm 104 mm 12Ω protection circuit BAV99 1Ω 10kΩ active area signal line Figure 4.20: Principle of variable strip readout. Exemplary shown is the readout of four strips. A strip has a surface of 0.0035m 2 including an active area of 0.0020m 2 . pulse height [0.244 mV] 500 450 400 350 300 250 200 150 55Fe Pulse Height vs # Strips Δ Ugem3= 330 V Δ Ugem2= 290 V Δ Ugem1= 320 V cm kV Edrift = 1.25 cm kV Etran1,2 = 2.00 Eind cm kV = 2.00 Ar:CO2 93:7 @ 1 bar fivefold seg anode unseg anode 100 0 1 2 3 4 5 # strips Figure 4.22: Pulse height as a function of the number of readout strips by CATSA82. C det detector preampifier Q det Q coup C coup Q fb R fb C fb A op amplifier Figure 4.21: Schematic of the charge sensitive preamplifier pulse height [0.244 mV] 1600 1400 1200 1000 800 600 Δ Ugem1= 315 V Δ Ugem2= 335 V Δ Ugem3= 355 V 55Fe Pulse Height vs # Strips cm kV Edrift = 1.25 cm kV Etran1,2 = 2.00 Eind cm kV = 1.67 U out Ar:CO2 93:7 @ 1 bar Canberra 2004 ELab 2010 linear fit to Canberra data linear fit to ELab data 400 0 1 2 3 # strips 4 5 Figure 4.23: Pulse height as a function of the number of readout strips recorded with Canberra2004 and ELab preamplifier, respectively. A linear function is fit to the data.
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DEVELOPMENT OF MICRO-PATTERN GASEOU
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Dedicated to Engin Abat 29/09/1979
Page 9 and 10:
Contents Introduction I 1 Interacti
Page 11 and 12: Introduction Our universe is moment
Page 13 and 14: is testing tubes with alternative d
Page 15: 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 68 and 69: 58 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 110 and 111: 100 Chapter B Construction Drawings
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102 Chapter B Construction Drawings
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104 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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