A Classic Thesis Style - Johannes Gutenberg-Universität Mainz

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18 introduction photo and electroproduction. This will be the extended variant in what follows. Table 2: Model Saclay-Lyon for Λ and Σ 0 production. Parameters of assumed resonances. resonance (I)J π mass (MeV) width (MeV) g1/v g2/t K ∗ (892) 1 − 892 50 -0.055 0.162 K1(1270) 1 + 1273 90 -0.194 -0.346 N(1440) P11 N(1720) P13 N(1675) D15 Λ(1405) S01 1 1 + 2 ( 2 ) 1 3 + 2 ( 2 ) 1 5 − 2 ( 2 ) 0( 1440 1720 1680 350 150 150 -0.015 -0.040 -0.630 0.000 -0.141 -0.047 1 Λ(1670) S01 − 2 ) 0( 1407 50 -0.416 0.000 1 Λ(1810) P01 − 2 ) 0( 1670 35 1.754 0.000 1 Σ(1660) P11 + 2 ) 1( 1810 150 -1.955 0.000 1 ∆(1910) P31 ∆(1232) P33 + 2 ) 3 1 + 2 ( 2 ) 3 3 + 2 ( 2 ) + ) 1660 1910 1235 1920 100 250 131 200 -7.331 0.649 -0.466 0.048 0.000 0.000 -1.876 0.290 ∆(1920) P33 3 3 2 ( 2 The version of the Saclay Lyon model [26, 35] (see table 2) used in this thesis (SL-A) shares with Kaon-Maid the same kaon resonances and the SU(3) constrains on the main coupling constants. The set of resonances goes up to spin 5/3 and only coincides with Kaon-Maid in the N(1720) for Λ production and in the P13(1910) ∆ resonance for Σ. Spin 1/2 hyperon resonances are used instead of hadronic form factors for counterbalancing the strength of the Born terms through a destructive interference with these u-channel resonances. S-LA and Kaon-Maid are good representatives of two main groups of these isobaric models which differ in the assumption of the hadronic form factors. Altought hadronic form factors are suposed to be important for the proper description of the process at large photon lab energies (since they suppress the cross section as a function of energy), this effect can also be accomplished in models without hadronic form factors. where the suppression is realized by inclusion of some hyperon resonances and nucleon resonances with higher spin (3/2 and 5/2). However, the method is not so convincing since the use of hadronic form factors is more flexible and simultaneously takes into account the fact that nucleons are composite objects. Models in which hadronic form factors. are not assumed and which include only one hyperon resonance overpredict the photo-production cross sections for photon energies larger than 2 GeV. Fig. 6 shows predicted cross-sections for Kaos kinematics (Q 2 = 0.036 (GeV/c) 2 and W = 1.67 GeV). It can be readily seen that in the region of very forward an-
(nb/sr) Ω /d σ d 400 350 300 250 200 150 100 50 1.5 kaon-maid and saclay-lyon isobaric models 19 K−Maid SLA SL 0 0 20 40 60 80 100 120 140 160 180 Θ K(Deg) Figure 6: Model predictions at Kaos kinematics (Q 2 = 0.036 (GeV/c) 2 and W = 1.67 GeV) for full angular range. Similar results are obtained for S-L, S-LA and Kaon-Maid at large angles. Strong damping is observed for small kaon angles in Kaon-Maid. gles these two types of isobaric models provide substantially different results for the cross section. The models with hadronic form factors reveal a damping of the cross section whereas the models without hadronic form factors continue rising. Although no data are available for comparison, the strong damping predicted by models with hadronic form factors is believed to be far from realistic [36]. This issue is one of main open problems in Kaon electroproduction [37]. Apart from the important discussion about the role of hadronic form factors in meson photoproduction a full understanding and modeling of kaon electroproduction is an essential ingredient for hypernuclear physics. Calculations of the cross section for production of hypernuclei depend on two main ingredients: the elementary-production operator and the nuclear and hypernuclear structure information. Understanding hypernuclear structure consequently relays heavily on getting the uncertainty regarding the elementary process well under control. Since hypernuclear studies are an important part of Kaos physics program, this issue is of importance. As a first step towards this important kinematical region, this thesis is dedicated to the measurement of Kaon electroproduction cross-section at very low momentum transfer although at only moderate kaon center of mass angle. Future experiments with Kaos spectrometer will address this crucial angular region where the cross section reaches its maximum value while different isobaric models widely disagree.
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 30 and 31: 20 introduction 1.6 previous experi
Page 32 and 33: 22 introduction Figure 9: Total cro
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
Page 41 and 42: M MWPC L F 2.4 kaos spectrometer 31
Page 43 and 44: Table 3: Spectrometers properties 2
Page 45 and 46: 2.4 kaos spectrometer 35 Figure 16:
Page 47 and 48: 2.4.5.1 Read out electronics 2.4 ka
Page 49 and 50: 2.4 kaos spectrometer 39 channels.
Page 51 and 52: 2.5 kaos single arm trigger 41 64MB
Page 53 and 54: 2.6 spectrometer b 43 Figure 23: Sc
Page 55 and 56: 2.7 coincidence setting 45 to be im
Page 57 and 58: 2.8 data acquisition and analysis s
Page 59: 2.9 kinematical setting 49 (GeV/c)
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68 detection efficiencies and data
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C O N C L U S I O N S The effort to
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cm [nb/sr] dσ v / dΩ K 1500 1000
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cm [nb/sr] dσ / dΩ K 500 400 300
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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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100 prototyping and efficiency meas
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102 prototyping and efficiency meas
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104 noise and radiation damage Figu
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106 noise and radiation damage Prob
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110 noise and radiation damage Figu
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112 noise and radiation damage Puls
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114 noise and radiation damage Tabl
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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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128 theoretical background for the
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130 theoretical background a.8 φ d
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132 theoretical background where σ
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134 theoretical background by showi
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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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