development of micro-pattern gaseous detectors – gem - LMU

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28 Chapter 3 The Triple GEM Prototype 1.0 Figure 3.1: Framed GEM foil of (100 × 100)mm 2 active area, as it is produced and delivered by CERN. Al Faraday cage O-ring gas exit acrylic glas 3 3 3 4 7 U cath U GEM 3 U GEM 2 U GEM 1 GRP base plate drift gap 4 transfer gap 2 transfer gap 1 induction gap Cathode GEM 3 GEM 2 GEM 1 Spacer Thread rod Figure 3.2: Exploded view of the triple GEM stack with spacers and drift cathode. 55 Fe X-ray inlet kapton sealing layer E cathode GEM 3 GEM 2 GEM 1 readout gas inlet signal line Figure 3.3: Schematic profile of the triple GEM detector. Dimensions are given in mm. Drawing not to scale. 12 20 16
3.2. HV Supply 29 The Cathode The cathode is made of a 36µm thick aluminum covered mylar foil, basically a metalized boPET 1 film, that warrants good electric properties with respect to high voltage as well as high stability and strength. The film is glued with epoxy on a 2 mm thick aluminum supporting frame which holds the same dimension as the fiberglass frames of the GEMs. The Anode An unsegmented 1.6 mm thick copper-clad PCB with (210 × 300)mm 2 base area, to suit the housing dimensions, was chosen for the first measurements. The anode area of (115 × 155)mm 2 is separated from the surrounding grounded copper top and bottom layer (cf. Fig. B.2). The collected charge is read out via a broad strip of 22 mm that is connected to the preamplifier and thus to the following electronics. For a further step of measurements, we implemented a fivefold segmented PCB 2 anode, with same dimensions but an active area of (100 × 104)mm 2 , divided into five equal strips of (100 × 20)mm 2 separated by 1 mm insulation length, see Fig.B.3, also surrounded by grounded top and back planes. 3.1.2 The Complete Housing A schematic profile of the detector is provided in Fig. 3.3. The gas volume of (170 × 240 × 20)mm 3 = 0.82 l is enclosed by a bottom plate and a frame made of GRP 3 . The top plate is made of acrylic glass for optical control possibility. O-rings between frame and PCB anode, which is mounted on the bottom plate, and between frame and top plate ensure the hermetic sealing of the volume. The gas is supplied to the detector volume via gas feeds on two sides of the frame. As Fig. 3.4 shows, there are also divider walls placed in the detector, guiding the gas flow through the active area, i.e. the triple GEM stack. Furthermore, seven drills are made for HV supply of the cathode and six GEM electrodes, placed on the right side in Fig. 3.4, oppositely to the readout side. To reduce noise, the whole detector is covered by a 2 mm thick Faraday cage and an additional conductive copper tape. For measurements with an 55 Fe irradiation source (cf. Ch. 4, Ch. 6 and Ch. 7), five holes, centered to the active area of the triple GEM detector, are installed in the top plate and sealed with kapton layers (see Fig. 4.6). 3.2 HV Supply Seven different voltages are needed to generate the high potentials on the GEM foils and the gaps. Fig. 3.6 shows an exemplary setup of voltages for the configuration. Decoupling capacitors are not implemented in the current setup since they were not needed. 1 Biaxially-oriented polyethylene terephthalate, a polyester film that is produced by stretched PET 2 Printed Circuit Board 3 Glass Reinforced Plastic
Page 1: DEVELOPMENT OF MICRO-PATTERN GASEOU
Page 5: 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 40 and 41: 30 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
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78 Chapter 8 Implementation of High
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88 Chapter 9 Summary and Outlook st
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90 BIBLIOGRAPHY [Bieb 03] O. Biebel
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92 BIBLIOGRAPHY [NIST 10] NIST. “
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94 BIBLIOGRAPHY
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96 Chapter A Assumptions for Effici
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98 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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