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In dieser Arbeit untersuche ich den Einfluss massiver Quantenfelder auf einen reinen de Sitter Hintergrund. Nach einer kurzen Zusammenfassung der neuesten Entwicklungen zu diesem Thema gebe ich eine Einführung in die klassische Geometrie von de Sitter Räumen. Darin behandle ich die physikalischen Eigenschaften und die verschiedenen Koordinatensysteme, die unterschiedliche Teile des de Sitter Raumes bedecken. Im anschließenden Kapitel wiederhole ich die Quantenfeldtheorie freier Skalarfelder auf gekrümmten Hintergründen im Allgemeinen und auf de Sitter im Speziellen. Hier gebe ich die Lösungen für die Modenfunktionen in geschlossenen und flachen Koordinaten an und diskutiere das Problem der richtigen Wahl des Vakuums auch im Hinblick auf die Eigenschaften der zugehörigen Green Funktionen. Da sich der Hintergrund für die Quantenfeldtheorie auf de Sitter mit der Zeitentwicklung ändert, verwende ich den in/in (Keldysh) Formalismus zur Berechnung von Observablen. Ich fasse den Formalismus zusammen und erläutere die für Rechnungen benötigten Methoden. Die Einführung des Wechselwirkungspotentials und der Feynmanregeln für Wechselwirkungsdiagramme bilden schliesslich den Abschluss des einleitenden Teils. Mit Hilfe des effektiven Potentials für das reskalierte Skalarfeld zeige ich, dass jede Theorie mit ungeraden Wechselwirkungspotentialen Probleme mit der Stabilität des freien Vakuums aufweist, falls der Skalenfaktor in der Vergangenheit verschwindet. Dies ist auch ein Argument, auf de Sitter die globalen Koordinaten anstelle der flachen zu verwenden, da sie im Gegensatz zu diesen den ganzen Raum bedecken und der Skalenfaktor nur einen nicht verschwindenden Minimalwert annimmt. Ich beweise weiterhin, dass aus der Betrachtung der Vakuumpersistenz kein Einwand gegen Wechselwirkungen auf de Sitter folgt, da die resultierende Entwicklung immer unitär ist, falls die Kopplung klein genug gewählt wird. Für die Schleifenkorrekturen zum Keldyshpropagator in globalen Koordinaten ergeben meine Berechnungen keine problematischen Divergenzen. Insbesondere finde ich keine Divergenz, die es verbietet, den adiabatischen Limes in Berechnung zu nehmen, was den Ergebnissen von Polyakov und Krotov widerspricht. Zusammen- fassend ist meine Schlussfolgerung, dass die wechselwirkenden Quantenfelder zu keinen offensichtlichen Instabilitäten des de Sitter Hintergrundes führen. / In this work I discuss the influence of interacting massive quantum fields on a pure de Sitter background. After a short review of recent developments on the topic, I give an introduction to the classical geometry of de Sitter. I discuss the physical properties and the different coordinate charts covering parts of de Sitter. In the next chapter I recapitulate free quantum fields on curved backgrounds in general and on de Sitter in particular. Subsequently I give the solutions to the mode equation for closed and flat coordinates and cover the problem of the correct choice of the vacuum also with respect to the properties of the corresponding Green function. As the background for quantum field theory on de Sitter is changing with time I use the in/in (Keldysh) formalism to calculate observables. I review this formalism and give the mathematical tools to perform calculations. The introduction of the interaction potential and the Feynman rules for interaction diagrams concludes the introductory part. Using the effective potential for the rescaled field, I show that any theory with odd interaction potential has problems with the stability of the free vacuum on a dynamic background if the scale factor vanishes in the early past. In particular this is one argument for using the global closed coordinate chart on de Sitter instead of the flat one covering only half of de Sitter. I also prove that from the vacuum persistence there is no objection to taking interactions on de Sitter, i.e. the resulting evolution is unitary for small enough coupling. For the loop corrections to the Keldysh propagator in global coordinates I calculate no problematic divergence, especially I find no divergence prohibiting the adiabatic limit in calculations in contrast to Polyakov and Krotov’s result. Summarizing, this shows that there is no obvious instability of the de Sitter background inferred by interacting quantum fields.

Germanium detectors are a choice technology in fundamental research. They are suitable for the search for rare events due to their high sensitivity and excellent energy resolution. As an example, the GERDA (GERmanium Detector Array) experiment searching for neutrinoless double beta decay is described. The observation of this decay would resolve the fundamental question whether the neutrino is its own antiparticle. Especially adapted detector technologies and low background rates needed to detect very rare events such as neutrinoless double beta decays are discussed. The identification of backgrounds originating from the interaction of radiation, especially alpha-particles, is a focus of this thesis. Low background experiments face problems from alpha-particles due to unavoidable surface contaminations of the germanium detectors. The segmentation of detectors is used to obtain information about the special characteristics of selected events. The high precision test stand GALATEA was especially designed for surface scans of germanium detectors. As part of this work, GALATEA was completed and commissioned. The final commissioning required major upgrades of the original design which are described in detail. Collimator studies with two commercial germanium detectors are presented. Different collimation levels for a beta-source were investigated and crystal axis effects were examined. The first scan with an alpha-source of the passivated end-plate of a special 19-fold segmented prototype detector mounted in GALATEA is described. The alpha-induced surface events were studied and characterized. Crosstalk and mirror pulses seen in the segments of the germanium detector were analyzed. The detector studies presented in this thesis will help to further improve the design of germanium detectors for low background experiments. / Germaniumdetektoren eignen sich für die Suche nach sehr seltenen Ereignissen, da sie aufgrund ihrer hohen Sensitivität und hervorragenden Energieauflösung geringe Mengen von Radioaktivität nachweisen können. Germaniumdetektoren finden daher zum Beispiel Anwendung beim GERDA (GERmanium Detector Array) Experiment, welches sich mit der Suche nach dem neutrinolosen doppelten Betazerfall beschäftigt. Die Beobachtung dieses Zerfalls würde die fundamentale Frage beantworten, ob das Neutrino sein eigenes Antiteilchen ist. Die experimentelle Voraussetzung zum Nachweis von sehr seltenen Ereignissen wie dem neutrinolosen doppelten Betazerfall sind niedrige Untergrundraten und speziell angepasste Detektortechnologien. Das GERDA Experiment sowie Methoden zur Untergrundminimierung werden vorgestellt. Unvermeidbare Oberflächenkontaminationen von Germaniumdetektoren erzeugen einen zusätzlichen intrinsischen Untergrund. Im Besonderen werden Oberflächenereignisse, die durch die Wechselwirkung von alpha-Teilchen, entstehen im Rahmen dieser Arbeit diskutiert. Eine spezielle Segmentierung der Detektoren liefert zusätzliche Informationen zur Unterscheidung von Signal und Untergrundereignissen. Ein eigens zur Untersuchung von Oberflächenereignissen entwickelter Hochpräzisionsteststand, GALATEA, wurde im Rahmen dieser Arbeit vollständig in Betrieb genommen. Die Inbetriebnahme der Apparatur erforderte umfangreiche Umbaumaßnahmen und die Implementierung zusätzlicher Komponenten. In der Vorbereitung wurden auch Kollimatorstudien an zwei kommerziellen Germaniumdetektoren durchgeführt. Das Kollimationsverhalten sowie Kristallachseneffekte wurden untersucht. Die Oberfläche eines speziell 19-fach segmentierten Prototyp-Detektors wurde erstmalig in GALATEA mit einer alpha-Quelle abgetastet. Oberflächennahe Ereignisse wurden untersucht und charakterisiert. Die hier vorgestellten Detektorstudien dienen der Untersuchung und Charakterisierung von Germaniumdetektoren. Die daraus gewonnenen Resultate können nützlich für die Identifizierung von Untergrundereignissen im GERDA Experiment sein oder generell Anwendung in Experimenten finden, die Germaniumdetektoren verwenden.

Die Untersuchung der Moduli Räumen von N = (2,2) Superkonformen Feldtheorien und der allgemeineren N = (2,2) Supersymmetrischen Quanten Feldtheorien ist ein langjähriges und vielseitiges Forschungsgebiet. Diese Dissertation konzentriert sich auf gewisse allgemeine Aspekte des erwähnten Studiums, und stellt Entwicklungen von allgemeinen Methoden im Rahmen der Topologischen String Theorie dar. Die vorliegende Arbeit besteht aus zwei Teilen. Der erste Teil befasst sich mit Aspekten der geschlossenen Topologischen String Theorie und kulminiert in den Inhalt von [52], wo die geometrische Struktur der Topologischen anti-Topologischen Moduli Räumen von N = (2, 2) Superkonformen Feldtheorien mit Zentral Ladung c = 9, angesichts eines allgemeinen Quantisieung-Rahmens [31, 32] wiederentdeckt wird. Aus dieser Sichtweise erhält man, als Spezialfall, eine klare Einsicht der “holomorphic anomaly equation” von [6]. Diese Arbeit könnte als eine natürliche Erweiterung von früheren Untersuchungen in ähnlicher Richtung betrachtet werden, insbesondere vom grundlegenden Artikel [104]. Der zweite Teil befasst sich mit Aspekten der Untersuchung der Offenen und Geschlossenen Moduli Räumen von Topologischen Konformen Feldtheorien auf Genus Null. Insbesondere, ist hier eine Exposition von [13] enthalten, wo allgemeine Resultate über die Klassifizierung und Berechnung von “bulk-induced” Deformationen von Offenen Topologischen Konformen Feldtheorien erhalten wurden. Letzteres wurde durch eine kohärente algebraische Methode erreicht was sich auf den definierenden L∞ und A∞ beteiligten Strukturen bezieht. Teilweise ist die letztere Untersuchung auf beliebige Affine B-twisted Landau Ginzburg Modelle beschränkt. Nachfolgend wird weitere originelle Arbeit dargestellt was die Topologische String-Feld-Theoretische Struktur von B-twisted Landau Ginzburg Modellen vollendet. Insbesondere wird eine “off-shell” Erweiterung der Kapustin-Li Formel von [41, 49] gegeben. Diese “off-shell” Formel bezeichnet einen konsolidierenden Baustein der algebraischen Herangehensweise zur Berechnung des Effektiven Superpotentials von B-twisted Affine Landau Ginzburg Modellen, und kann damit als eine natürliche Entwicklung von der grundlegenden Arbeit [12] betrachtet werden. / The study of moduli spaces of N = (2, 2) superconformal field theories and more generally of N = (2, 2) supersymmetric quantum field theories, has been a longstanding, multifaceted area of research. In this thesis we focus on certain selected general aspects of this study and develop general techniques within the framework of topological string theory. This work is naturally divided into two parts. The first is concerned with aspects of closed topological string theory, and culminates with the content of [52], where the geometrical structure of the topological anti-topological moduli spaces of N = (2,2) superconformal field theories with central charge c = 9 is rediscovered in the light of quantization, within a general framework ([31, 32]). From this point of view, one thus obtains, as a special case, a clear understanding of the holomorphic anomaly equation of [6]. This work can be viewed as a natural continuation of earlier studies in the same direction, most notably the seminal paper [104]. The second part is concerned with aspects of the study of the open and closed moduli space of topological conformal field theories at genus zero. In particular, it contains an exposition of [13], where general results on the classification and computation of bulk- induced deformations of open topological conformal field theories were obtained from a coherent algebraic approach, drawing from the defining L∞ and A∞ structures involved. In part, the latter investigation is restricted to arbitrary affine B-twisted Landau Ginzburg models. Subsequently, further original work is presented that completes the topological string field theory structure of B-twisted Landau Ginzburg models, providing in particular an off-shell extension of the Kapustin-Li pairing of [41, 49]. This off-shell pairing constitutes a consolidating building block in the algebraic approach to the computation of the effective superpotential of B-twisted affine Landau Ginzburg models pioneered in [12].

We present a study of the galaxy populations in massive galaxy clusters selected by their Sunyaev–Zel’dovich Effect (SZE) signatures. Selection via the SZE is approximately mass- limited where the mass limit varies only slightly with redshift, making it an ideal selection method for studying the evolution of the galaxy content of clusters. We begin by introducing the SZE, the South Pole Telescope (SPT), and the larger research project in which this Thesis is embedded. We then present the core galaxy population studies of this Thesis. In Chapter 3, we present the first large-scale follow-up of an SZE-selected galaxy cluster sample. Of 224 galaxy cluster candidates in the sample, we optically confirm 158 clusters and measure their photometric redshifts. We find a redshift range of 0.1

Remote sensing has become an essential tool to improve data collection and spatial analysis in the geosciences. Identification of passive margin structures that are exposed along the Egyptian coast of the Red Sea, and their control on landforms has been hampered by limited data resolution and restricted access to this arid and inaccessible region. A major challenge lies in distinguishing features in the landscape that formed due to long-term tectonic activity and erosion from those features that modified the landscape recently. The goals of this thesis were to determine to what degree the study area is currently tectonically active, and what major hazards might affect the touristically developing coastal region. This study deals with the structural and geomorphological evolution of the rift-related structures and their impact on the sediment distribution and landforms variation in the northern Quseir area. In such a remote desert area, field and remote morphostructural analysis are needed to understand the structural and geomorphological evolution. The current study is mainly based on high-resolution QuickBird image analysis and field investigation. Field mapping was limited to one season, owing to acute safety concerns in the Eastern Desert. In the study area, the pre-rift stratigraphy includes Pan-African basement rocks overlain by pre-rift clastic and carbonate successions that range in age from Cambrian to Eocene. Syn-rift clastic and carbonate rocks range in age from Late Oligocene to recent and show depositional patterns controlled by fault systems. The field area exposes a section of a tectonically uplifted, amagmatic sedimentary sequence, which formed due to passive-margin-related rifting of the Red Sea: the Mesozoic and Tertiary sedimentary units that fill the 7-km wide coastal strip are perfectly exposed as tilted fault blocks. The results of my field mapping and structural analysis show that the fault architecture of the area is dominated by a large NW-SE-striking fault system. A series of SE-dipping normal faults are consistent in cross-section with listric fault geometry, rooting into an E-dipping detachment at depth. Our mapping also revealed that left-steps in at least one of the major NS- striking faults are accommodated by a flower structure, but not by SW-NE-oriented cross faults as previously proposed in a neighboring area. Thus seismic activity is more likely to occur on the large NW-striking normal faults, leading to potentially larger Magnitude earthquakes than previously recognized in the area. The left-step may act as a barrier to rupture propagation and should be examined in more detail. The northwestern Red Sea coast is part of the straight coastal segment that is generally characterized as seismically inactive. However, during the geological field mapping, I found evidence for Plio-/Pleistocene vertical coastal uplift, likely due to earthquake-related coastal and offshore faulting. Pliocene marine deposits emerged recently due to sea level-drop and earthquake-related uplift. Even the presence of up to five distinct Pleistocene coral terraces implies that at least some of the coastal uplift was seismogenic, because terraces of the same age can be found at different elevations along strike. Presumably, some of the seawarddipping, N-S-striking normal faults are active today, despite the lack of recent instrumental seismicity. These findings imply long recurrence intervals for active faults in the northern Quseir area. These results differ from previously published results for the adjacent Quseir-Um Gheig sub-basin area, were E-W-striking strike-slip faults were mapped to offset the N-Sstriking faults, and had been inferred as earthquake-generating faults by Abd El-Wahed et al. (2010). Based on our mapping, we postulate that the large rift-parallel normal faults are seismogenic. Drainage network evolution within the study area is often structurally controlled and the nature of these controls was examined in this study. The Wadi Siatin stream channel network is classified in a relatively simple way, based on the high-resolution satellite data, with dendritic, and rectangular considered the most fundamental channel geometries. It was possible to distinguish the different morphological elements of the network, as well as the anomalies that affect the patterns. This analysis revealed, in the northern Red Sea area basins, the existence of old structures whose successive reactivations have left their mark on the drainage network. Comparison of joint systems direction with the directions of the main trunk stream channel of Wadi Siatin shows that the channel is highly affected by tectonic jointing. First-order channels follow easily erodable faults. Investigations concerning the relationship of stream-flow orientation with geological structure in the Wadi Siatin Basin shows that, generally, the least influenced flows are those of first-order which are governed simply by the valley side slopes on which they developed. However, in certain geological and geomorphological situations, there are clear exceptions to this generalization. Certainly, locally, geological control of these small streams may be even higher than in many streams of higher order. In the peripheral parts of the Basin, expansion of drainage into the available space has obviously been easiest along lines of weakness and, as a consequence of this, streams of the first order come to exhibit a high degree of adjustment to the underlying structure. The maximum structural control is reached by the streams of the third order. Towards the higher orders, the influence of local structure becomes weaker.

The study deals with the two main problems in geographical education: How to inform students about a spatial practicing learning and teaching and how to evaluate this form of learning in comparison to theoretical non spatial forms of learning. The classic form of spatial learning is the outdoor excursion. But there are some new and actual alternatives when realizing the former intended aims of a spatial learning, so for instance didactical pathways, field trips or field works, but also the new way of geocaching and learning by GPS when dealing with the themes of orientation or finding out points of geographic importance for explaining the genetic processes. The necessary skills can be combined to improve the success of learning and to maximize the motivation. The base of this motivation behavior is the existence of a hide and seek-game as a modern version of a scavenger hunt. This motivates the students and is furthermore the attraction of Geocaching. Methodical skills can also be trained very automatically during this search. The GPS devices are of common use in the daily life and its use may increase much more in the fu-ture and in geographical use, too. Nowadays the literature about this theme is merely descriptive and thematically reduced to the function of orientation. The first study describing the learning suc-cess of using GPS devices and Geocaches in geography class had been made by NEEB. She tested the variation of the competence of orientation in different old classes when examining the use of GPS devices and Geocaches. Even though GPS devices and Geocaches are very efficient for instructing the students’ competence of orientation there may be the question, in what forms and circumstances the learning can be done. The time and effort necessary to generate a didactical and educational trail has to be justified against the background of the achieved learning effect. Educational trails need students, walking outside of the schools, looking for information along teaching paths and learning by the results. This active experienced learning leads to a better understanding of the environment, the outdoor circumstances and the people living in this area. You can structure such educational trails by Geopoints, this means points of a special geographic interest. Geocaches can structure such paths didactically. These structuring points are GEOpoints. The tasks at such Geopoints are structured didactical as well. GPS devices and Geocaches are complementing one another. They fulfill an important function in geographic orientation and the respective local information. Two important ministries in Germany (Bavaria, Baden-Württemberg) demand the use of extra¬curri-cu¬lar educational objectives in geography education. This means: visiting locations outside of the school and using the advantages of a fully learning by excursions. Neurobiology supports the idea that pupils completing the educational trail will learn much more and efficiently than students in “normal” classes: Indeed: A successful contextualization of modern geomedia stimulates the motivation. Geocaches are suitable for didactical structuration and motivation. A better and more comprehensive addressing to all senses will lead to a better sustainability. When testing the advantage of excursional learning comparing the same themes with a classical learning at school you have to differ within the students capacity of learning and the cognitive and methodical competence. For 17years aged students the theme of “Umgestaltung von Flusslandschaften“ (rearrangements of fluvial topography) was chosen because using this example of anthropogenic rearrangements of the Rheinaue wetlands near Karlsruhe shows the interdependency between human and environment was in the direct neighborhood of the students. Therefore the excursion could be realized very good without long transports. The “Nördlinger Ries” between the Swabian and the Franconian Jura is an impact-crater of world-wide importance. This location had been chosen for Students of grade 5 (10 years old students). The themes to work out were: The typical elements of the Swabian Jura (karst formation, hydrogeology, typical vegetation) and the special forms of the impact tectonics. The sustainability of educational trails using GPS had been evaluated by the answers of 441 ques-tionnaires. In grade 5 a multiple-choice-test had to be answered while grade 11 had to answer open questions in complete sentences. The influence of the teachers on the overall result is being kept low through the random selection, the number of the comparison groups and the teaching manuals. The overall results of these questionnaires show that the students of grade 5 which completed the educations trail achieved 11% higher scores in areas of the cognitive performance compared to the students who experienced classical learning at school. In grade 11 the students who completed the educational trail received 5% higher scores. Both differences in the results are significant and show a magnitude of effect, which is high in certain items. Consequently, the study has proven that educational trails evocate better cognitive performances than classical learning at school. The current state of research suggests that the development of environmental trails from teachers for teachers is not sustainable because the teachers don’t have the time to refine environmental trails didactically. The experience while creating the educational trails and the feedback of the participant teachers showed that teachers should cooperate for creating educational trails. The strain for each single person is reduced and the regularly use of the educational trails can be assured.

In dieser Arbeit wird ein schnelles Strahlungsmodell im sichtbaren Spektralbereich erstellt. Ausgehend vom von einem meteorologischen Modell berechneten Zustand der Atmosphäre ergibt dieses Strahlungsmodell die Strahldichte am oberen Rand der Atmosph äre, die ein Satellit messen würde, wenn die Atmosphäre tatsächlich so aussehen würde (synthetisches Satellitenbild). Der Vergleich mit einem tatsächlichen Satellitenbild gibt Hinweise über mögliche Fehler des meteorologischen Modells. Mehrere Forschungsrichtungen werden in dieser Arbeit untersucht. Das Endprogramm (pastat) basiert weitgehend auf Look-Up Tables. Eine Erweiterung der Eddington-Approximation bis auf die dritte Ordnung wird verwendet, um die azimutal gemittelte Strahldichte zu berechnen. Ein Ansatz mit 16 statistisch bestimmten Parametern bringt die notwendige azimutale Abhängigkeit. Das Genauigkeitskriterium für das zu erstellende Strahlungsmodell ist ein relativer Fehler der Re�ektivität unter 10% oder ein absoluter Fehler unter 0.02. Die Erfolgsrate von pastat hängt stark vom Sonnenzenitwinkel ab. Der mittlere relative Fehler von pastat ist eine Gröÿenordnung höher als der von den meisten vorhandenen schnellen Strahlungsmodellen im Infraroten. Im Sichtbaren bringt der Mehrfachstreuterm der Strahlungstransportgleichung nämlich eine erhebliche zusätzliche Erschwernis im Vergleich zum Infraroten. Jedoch wird das Erfolgskriterium in fast allen Fällen von pastat eingehalten. Somit erlaubt dieses Verfahren, Modellfehler auf 10% Genauigkeit zu detektieren. pastat ist das erste schnelle Strahlungsmodell im sichtbaren Spektralbereich für wolkige Atmosphären.