Master Theses

The studies in this thesis are motivated by the measurement of the top quark Yukawa coupling Ytrelative to the SM value in the dileptonic decay channel of top-antitop (t¯t) pairs at the ATLAS experiment. The used (simulated) data correspond to the proton-proton collision data recorded between 2015 and 2018 at √s=13 TeV with an integrated luminosity of 140 fb−1. [...]

Pathological iron accumulation in the brain is a hallmark of several neurodegenerative diseases like Parkinson’s, Alzheimer’s and Huntington’s disease. Magnetic resonance imaging offers a unique non-invasive method to measure brain iron because iron affects the spin relaxation parameters of water protons and magnetic susceptibility of the brain tissue [...]

The Dark Photon is a hypothetical particle that can be possibly detected in the experiment because of its kinetic mixing with the ordinary, visible photon. In theories where dark matter is explained by the existence of a ’dark sector’, interacting with the visible sector of the Standard Model via gravitation, the photon of the dark sector, the Dark Photon (A_D ), might be the only visible manifestation of the dark sector. [...]

In this thesis, it is shown that ocean-generated microseism significantly impacts the synchronisation performance of the European X-ray free-electron laser (XFEL), which is based on a high-energy linear accelerator. Using superconducting technology, it generates hard X-ray pulses at megahertz frequencies. [...]

This thesis focuses on two fundamental limitations that affect the power scaling of cryogenically cooled high-power solid-state lasers: (i) Fractional thermal load (FTL) and (ii) Thermal and population lensing. For FTL, a novel method is introduced for the direct measurement of fractional thermal load in cryogenically cooled laser crystals. [...]

In this work, the synthesis of star-shaped octapod iron oxide nanoparticles was analyzed. The synthesis is based on the thermal decomposition of iron(II) oleate, which in turn wassynthesized from iron(II) carbonate and oleic acid. [...]

Platinum palladium alloy nanoparticles are of high interest because of their role ascatalysts for different processes, including exhaust control and methane oxidation. Cata-lyst behavior is determined by the shape, structure and alloy composition of the particles.To enhance catalyst efficiency, it is thus necessary to improve our understanding of thestructure of the nanoparticles and the active adsorption sites. [...]

Silicon Photo-Multipliers (SiPMs) are pixelated semiconductor detectors consisting of SPADs, usually used as single-photon sensitive detectors. SiPMs are often analog devices that require separate digitization. [...]

AbstractThis master’s thesis explores the ageing effects, offset calibration, and cross-talk inthe pixel vertex detector (PXD) of the Belle II experiment. The PXD is the innermostdetector of the Belle II experiment, consisting of self-supporting ladders using DEP-FET technology. [...]