Bachelor Theses

Obwohl etwa 85% der gesamten Materie im Universum aus Dunkler Materie besteht (vgl.Eidemüller 2017: 5), ist ihre Natur bisher noch ungeklärt. Lediglich die Gravitationswirkung, die Dunkle Materie auf sichtbare Materie zu hab en scheint, ist erwiesen. [...]

Laser beam induce current (LBIC) and X­ray beam induced current (XBIC) are effective tech­niques for mapping the spatial electrical performance of solar cells. Conducting precise currentmeasurements up to the femto­Ampere range is challenging and susceptible to noise [...]

X­ray beam induced current (XBIC) and laser beam induced current (LBIC) measurements en­able the point by point correlation of solar cell performance with complementary measurementmodalities in scanning microscopy.In this Bachelor’s thesis a complete mini­module with a mono­crystalline silicon solar cell in­cluding housing was measured using a 28keV X­ray beam and a 532nm laser beam as a probe.In particular, the influence of an Ag finger front contact on the multi­model signals induced bythe two measurement probes was compared.The hard X­ray photons were nano­focused and the energy was chosen that the beam can pene­trate the complete module and excite the AgK electrons in the Ag fingers. The strong absorptanceof the Ag fingers can be clearly seen in the X­ray transmittance measurements. [...]

Recent discoveries in the area of cosmology, like the proposition of dark matter, haveindicated that there may be additional particles beyond the Standard Model which mayexplain the phenomena of Dark Matter in the Universe. Among many suggestions ofwhat Dark Matter actually is, there are models such as two-Higgs doublet Models thatpredict the existence of additional scalar (H) or pseudoscalar (A) Higgs bosons whichcould function as mediators between Standard Model and Dark Matter particles. [...]

An important part of research and development (R&D) in the field of superconducting radiofrequency cavities is quench detection since these local breakdowns of superconductivity primarilylimit the cavity performance. Due to the detection of second sound waves propagating inliquid helium, the localization of quench spots on superconducting radio frequency cavities no longer requires the laborious attachment of many temperature sensors. [...]

In this bachelor thesis a feasibility study is carried out about assembling and programming a control unit for the 6 axis positioning robot EASy P1 series. The positioning robots will be used at DESY Research Center to adjust accelerator components. [...]

Hadronische Wechselwirkungsmodelle spielen eine zentrale Rolle in der Teilchenphysik, weil sie unter anderem zum Vergleich experimenteller Daten von durch Cherenkov-Teleskopen detektierten Luftschauern genutzt werden, um Eigenschaften des primären Luftschauerteilchens abzuleiten. In dieser Arbeit werden die beiden hadronischen Wechselwirkungsmodelle EPOS-LHC und QGSJETII-04 für gamma-ähnliche Luftschauer in deren ersten Wechselwirkung durch Monte Carlo Simulationen untersucht. [...]

Perovskite solar cells are a promising photovoltaic technology with their low production costsand high efficiencies. The main reason the technology is not ready for the market yet is the instability of the perovskite absorber and its fast degradation. [...]

X-ray fluorescence measurements are an ideal method for measuring the elemental distributions in samples but complications like self absorption make the evaluation of these measurements non-trivial – especially when using multiple detector modules. This is further complicated when studying low concentrations of elements, where accurate background subtraction and elemental sensitivity is essential. [...]

Scanning X-ray microscopy measurements are an indespensible tool of solar cell research to-day, and the compatibility with complementary measurement modes is a particular strength. This Bachelor’s thesis investigates a series of thin-film solar cells with a Cu(In,Ga)Se2(CIGS) absorber layer that differ in their overall ratio of gallium to indium, resulting in a varyingbandgap. [...]