A Classic Thesis Style - Johannes Gutenberg-Universität Mainz

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36 experimental setup and data acquisition (a) (b) Figure 17: Measured efficiency for a set of different gas mixtures and pregap voltages as a function of the anode voltage. A saturation region or plateau is observed in all cases and a clear dependency of the plateau starting point on the other operating parameters can be seen. The effect of the pregap is shown in subfigure (b) where the pregap voltage is set to zero. Larger anode voltages are needed to achieve the same detection efficiency. and isobutan (C4H10): 7% at an anode voltage of 4.8 kV, and a pre-gap voltage of 7.5 kV. For their final installation in Kaos platform, the gas tubing system was renewed, optimizing gas flow and ensuring mixture uniformity within the chamber volume. 2.4.5 Scintillator walls Two scintillator walls, labeled F and G, are used as timing and trigger detectors in the positive arm Kaos detector package. The F detector, located approximately in the focal plane of the spectrometer, consists of 30 plastic scintillators paddles (38 cm x 3.7 cm x 2 cm) of type Pilot F (modern equivalent: BC408) and 8 cm long lucite light guides. The paddles are tilted by 37 ◦ around the longitudinal axis in order to achieve an almost perpendicular flight path of the incoming particles into the 3.7 cm face. The total length covered by the wall is 1.89 m. The scintillators are read out in both ends by 2 in. Hamamatsu R1828 phototubes to allow for light propagation compensation.A momentum resolution of about 4% is obtained with these 3.7 cm wide paddles. The G detector was added to the system permitting the implementation a rough angular selection trigger. It also consists of 30 scintillator paddles (47 cm x 7.5 cm x 2 cm), with a purely flat geometry spanning a length of 2.2 m and read out by the same type of phototubes. Plastic scintillator material is BC408. This fast scintillators (2.1 ns decay constant) are very suitable for time of flight measurements and still feature a large absorption length of 380 cm.
2.4.5.1 Read out electronics 2.4 kaos spectrometer 37 Scintillator paddles are grouped in sets of eight channels (see Fig. 18). Analog signals from top and bottom photomultipliers are directed to a sum and splitter card (GSI SU 1601). 12% of the signal charge is delayed 250 ns until the trigger condition is generated and integrated by a LeCroy 1885F ADC, and 88% is sent to the constant fraction module CF8105. Eight inputs are handled simultaneously and fed after a logic delay module (GSI 1610:500 ns) as start signals into the LeCroy 1875 TDC by a flat cable. Both Lecroy modules are located in a FASTBUS crate. The sum output is used as a top bottom coincidence first level trigger condition. The signal is discriminated and then sent to the main positive arm trigger, implemented in the FPGA based VUPROM logic module. 4 Figure 18: Scheme of scintillator walls electronics. See text for explanation. 2.4.5.2 Calibration Both walls were in use for several years at the GSI. After the necessary refurbishment, a complete characterization was performed in order to decide whether or not their use for electroproduction experiments at <strong>Mainz</strong> was feasible. Time resolution and absorption length were measured for a sample paddle with a set of trigger detectors for cosmic muons, that allowed a reliable hit position determination 4 CFD, splitters and delays were used previously in the GSI setting. All modules were checked prior to their installation in Kaos electronic racks.
Page 1: M E A S U R E M E N T O F T H E U N
Page 5: A B S T R A C T The new stage of th
Page 9 and 10: C O N T E N T S i kaon electroprodu
Page 11: Part I K A O N E L E C T R O P R O
Page 14 and 15: 4 introduction Lorentz invariance.
Page 16 and 17: 6 introduction appear in the K + Λ
Page 18 and 19: 8 introduction there was almost no
Page 20 and 21: 10 introduction This allows us to w
Page 22 and 23: 12 introduction K ¡p γ ∗ Λ(Σ
Page 24 and 25: 14 introduction means of the isobar
Page 26 and 27: 16 introduction amount of resonance
Page 28 and 29: 18 introduction photo and electropr
Page 30 and 31: 20 introduction 1.6 previous experi
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Page 35 and 36: E X P E R I M E N TA L S E T U P A
Page 37 and 38: 2.3 target 27 Figure 11: Schematic
Page 39 and 40: 2.4 kaos spectrometer 2.4 kaos spec
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Page 43 and 44: Table 3: Spectrometers properties 2
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Part II F E A S I B I L I T Y S T U
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90 conclusions Figure 55: Emission
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92 prototyping and efficiency measu
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118 conclusions been tested and fou
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120 theoretical background photopro
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122 theoretical background effect o
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124 theoretical background A physic
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126 theoretical background taken in
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130 theoretical background a.8 φ d
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136 theoretical background With thi
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138 bibliography [16] J. C. David,
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140 bibliography [44] M. Bockhorst
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142 bibliography [71] P. Achenbach
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144 bibliography [98] S. Nozawa and
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146 bibliography Figure 24 Spek B d
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Figure 73 Annealing at 80° of the
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A Classic Thesis Style - Johannes Gutenberg-Universität Mainz

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