Inhaltszusammenfassung

Future electron-positron collider, as the planned International Linear Collider (ILC), are predestined for precision measurements, for instance of the Higgs boson, because of their well-defined initial conditions. They are therefore complementary to proton-proton colliders, as the Large Hadron Collider (LHC), which in particular stands out with the highest center of mass energy of up to √s = 13 TeV and significantly contributes to the search of new physics. On the other hand, precision measur...Future electron-positron collider, as the planned International Linear Collider (ILC), are predestined for precision measurements, for instance of the Higgs boson, because of their well-defined initial conditions. They are therefore complementary to proton-proton colliders, as the Large Hadron Collider (LHC), which in particular stands out with the highest center of mass energy of up to √s = 13 TeV and significantly contributes to the search of new physics. On the other hand, precision measurements allow to validate the standard model, or rather to search for possible deviations. A major requirement for such precision measurements is a high energy resolution of particle detectors, which is supposed to be achieved by means of the Particle Flow Approach, that requires a high granularity of the detector. The CALICE Analog Hadron Calorimeter (AHCAL) is developed for this purpose and is based on 30 x 30 x 3 mm^3 small scintillator tiles read out by Silicon Photomultipliers (SiPM). SiPMs are novel photo detectors, which consist of an array of up to thousands of pixels, each operated in Geiger-mode comparable to avalanche photodiodes. This thesis presents a study of the response saturation of SiPMs, on the one hand in a stand-alone operation and on the other hand in a combined SiPM-tile system within an AHCAL prototype, where testbeam data are utilized. These data comprise µ-, e- and π- measurements which have been recorded at the Super Proton Synchrotron (SPS) at CERN in July 2015. The analysis of testbeam data by means of simulations are an essential part of this thesis. In the course of this thesis, a setup has been put into operation which enables an automated measurement of the response saturation of stand-alone SiPMs. The results of these measurements are compared to different response models and show, as expected, a significant dependence of the saturation behavior to the total number of pixels of a SiPM. Especially, the probability for optical crosstalk also shows a clear impact on the response. Moreover, over-saturation is observed for some SiPMs. The second part of this thesis is about the analysis of testbeam data of the AHCAL prototype, which consists of 14 active layers. The non-availability of in total four of these layers, as well as the utilization of various layer generations with different SiPM-tile configurations, in particular complicate this analysis. An unforeseen low-energy background in electron data demands special event selections and adjustments to the simulation to ensure their compatibility. A method is developed which allows to analyze the response of the SiPM-tile system by utilizing testbeam data and simulation. Once again, a clear dependence to the total number of SiPM pixels is apparent, as well as to the optical crosstalk probability. In a final step, the linearity and energy resolution of the prototype are investigated and conclusions are drawn concerning optimization possibilities.» weiterlesen» einklappen

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Klassifikation

DDC Sachgruppe:
Physik