Kies- / Sandkörper im Wesertal zwischen Rinteln und Porta Westfalica

In this article the sand-/gravelbodies from Hausberge-Veltheim and Krankenhagen- Möllenbeck in the Wesertal are described and compared considering their depositional and architectural regime. A scenario is developed to explain the genetic sequence of the deposits. The sand-/gravel-body exposed at Krankenhagen-Möllenbeck was deposited first in form of a marginal käme. Subsequently during the Drenthe-stade of the Saale ice age, the sedimentation of the sand- /gravelbody at Hausberge-Veltheim took place under the depositional environment of an end- moraine.Die im Wesertal liegenden Kies-/Sandkörper von Hausberge-Veltheim und Kranken- hagen-Möllenbeck werden hinsichtlich Aufbau und Genese beschrieben und miteinander verglichen. Es wird ein Szenario aufgestellt und die genetische Abfolge beider Ablagerungen zueinander plausibel dargelegt. Der Kies-/Sandkörper von Krankenhagen-Möllenbeck wurde in Form eines Randkames aufgeschottert; im weiteren Verlauf des Drenthe-Stadiums der Saale-Kaltzeit kam es dann zur Sedimentation des Kies-/Sandkörpers von Hausberge-Veltheim als Satzendmoräne

(g−2)μ(g-2)_\mu at four loops in QED

We review the four-loop QED corrections to the anomalous magnetic moment of the muon. The fermionic contributions with closed electron and tau contributions are discussed. Furthermore, we report on a new independent calculation of the universal four-loop contribution and compare with existing results.Comment: 6 pages, Contribution to the proceedings of the International workshop on e+e- collisions from Phi to Psi 2017, v2: references adde

MS‾\overline{\rm MS}-on-shell quark mass relation up to four loops in QCD and a general SU(N)(N) gauge group

In this paper we compute the relation between heavy quark masses defined in the modified minimal subtraction and on-shell scheme. Detailed results are presented for all coefficients of the SU$(N_c)$ colour factors. The reduction of the four-loop on-shell integrals is performed for a general QCD gauge parameter. Some of the about 380 master integrals are computed analytically, others with high numerical precision based on Mellin-Barnes representations, and the rest numerically with the help of {\tt FIESTA}. We discuss in detail the precise numerical evaluation of the four-loop master integrals. Updated relations between various short-distance masses and the $\overline{\rm MS}$ quark mass to next-to-next-to-next-to-leading order accuracy are provided for the charm, bottom and top quark. We discuss the dependence on the renormalization and factorization scale.Comment: 53 pages, 11 figures, v2: minor changes, references added, corresponds to published versio

Annealing-Induced Changes in the Nature of Point Defects in Sublimation-Grown Cubic Silicon Carbide

In recent years, cubic silicon carbide (3C-SiC) has gained increasing interest as semiconductor material for energy saving and optoelectronic applications, such as intermediate-band solar cells, photoelectrochemical water splitting, and quantum key distribution, just to name a few. All these applications critically depend on further understanding of defect behavior at the atomic level and the possibility to actively control distinct defects. In this work, dopants as well as intrinsic defects were introduced into the 3C-SiC material in situ during sublimation growth. A series of isochronal temperature treatments were performed in order to investigate the temperature-dependent annealing behavior of point defects. The material was analyzed by temperature-dependent photoluminescence (PL) measurements. In our study, we found a variation in the overall PL intensity which can be considered as an indication of annealing-induced changes in structure, composition or concentration of point defects. Moreover, a number of dopant-related as well as intrinsic defects were identified. Among these defects, there were strong indications for the presence of the negatively charged nitrogen vacancy complex (NC–VSi)−, which is considered a promising candidate for spin qubits

Eiszeitliche Ablagerungen in Hochlagen des Süntels (Süd-Hannover) und seinen Karstschlotten

Aus dem Karstgebiet des Riesenberges im Süntel werden hochgelegene kies- und steinführende Ablagerungen verschiedenen Alters beschrieben. Außer kiesführenden Höhlensedimenten präglazialen Alters treten kiesführende Ablagerungen auf, die eiszeitlich entstanden sind. Während die Kies- und Steinanteile der präglazialen Ablagerungen aus lokalen (Kalkstein des Malm) und z. T. ortsfremden Komponenten (Sandstein des Wealden) bestehen, enthalten die jüngeren Ablagerungen zusätzlich Kiesanteile aus nordisch-skandinavischen Gesteinen sowie resedimentierten Weserkies. Die eiszeitlichen Ablagerungen wurden im Kammbereich sowie in Karsthöhlen abgelagert.Gravel deposits positioned in high altitude areas of Süntel Mountains are described from the carst area of Riesenberg. Not only cave gravel of pre-glacial age, but also those of glacial age occur. While the pre-glacial deposits comprise local, but xenotopic components, the younger ones display also material of northern derivation as well as reworked gravels from the Weser-River. The sediments were deposited both in caves and at summit region of the Süntel Mountains. Conditions of deposition and age relation to the glaciations are discussed

Optimization of the SiC Powder Source Material for Improved Process Conditions During PVT Growth of SiC Boules

We have studied the influence of different SiC powder size distributions and the sublimation behavior during physical vapor transport growth of SiC in a 75 mm and 100 mm crystal processing configuration. The evolution of the source material as well as of the crystal growth interface was carried out using in situ 3D X-ray computed tomography (75 mm crystals) and in situ 2D X-ray visualization (100 mm crystals). Beside the SiC powder size distribution, the source materials differed in the maximum packaging density and thermal properties. In this latter case of the highest packaging density, the in situ X-ray studies revealed an improved growth interface stability that enabled a much longer crystal growth process. During process time, the sublimation-recrystallization behavior showed a much smoother morphology change and slower materials consumption, as well as a much more stable shape of the growth interface than in the cases of the less dense SiC source. By adapting the size distribution of the SiC source material we achieved to significantly enhance stable growth conditions