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Low Gain Avalanche Diodes for Beam Monitoring and Reaction Time Determination at High Rates in HADES
No full textThe Low Gain Avalanche Diode (LGAD) technology enables high precision timing in the order of σₜ ≈ 30 ps for Minimum Ionizing Particles (MIPs), while simultaneously featuring high spatial resolution and excellent radiation hardness (operational up to fluences of Φₙₑ > 10¹⁵ nₑ/cm²). This technology sparked interest in the High Energy Physics (HEP) community for example for 4D-trackers (i.e. track reconstruction in coordinate space and time), beam monitoring and even medical applications. Due to those excellent properties of LGADs, the High Acceptance Di-Electron Spectrometer (HADES) collaboration employed LGADs as sensors for its in-beam Start detector, responsible for reaction time (T0) determination as well as beam spatial and time structure monitoring for the high rate p+p production beam time with a beam kinetic energy of 4.5 GeV in February 2022. Therefore, a dedicated HADES LGAD production was launched at Fondazione Bruno Kessler. This work will focus on the application of LGADs for the HADES Start detector and the fulfillment of the above mentioned tasks. After a presentation of the HADES LGAD production, the results of the full system test for the LGAD-based Start detector will be presented, indicating the viability of using LGADs for the purposes of the HADES Start detector. The performance as a beam time-structure monitoring tool at the p+p experiment will be shown, followed by a detailed discussion on the applied calibration and T0 reconstruction algorithms. The performance of the LGAD-based Start detector will be presented w.r.t. the reached T0 reconstruction efficiency and its precision as well as the sensor efficiency and radiation hardness over the entire p+p production beam time. After a full calibration of the sensor, T0s could be reconstructed with precisions of σ(T0) < 90 ps, when both sensors were used for the reconstruction, while single sensor T0 precisions up to σ(T0) ≈ 120 ps were achieved. The performance of the LGAD sensors deteriorated after the accumulation of radiation damage. Its effect will be presented for a selected single sensor. In order to demonstrate the excellent T0 reconstruction precision and accuracy, an analysis of the inclusive charged pion production was conducted employing only a particle identification via time of flight and momentum measurements. The resulting inclusive production cross section of σ(π⁺) ≈ (35.3 ± 4.6) mb and σ(π⁻) ≈ (9.7 ± 1.5) mb will be put into context with measurements of other experiments using p+p collisions
On Elastic Stability and Positive Definiteness for One-Dimensional Quasicrystals
No full textIn this work, a proper formulation of the elastic stability and positive definiteness of the elastic energy density of one-dimensional quasicrystals is provided. Based on an appropriate Voigt notation, the Sylvester criterion is applied and the necessary and sufficient conditions for the positive definiteness of the elastic energy density imposed on the elastic constants are derived for each Laue class from 4 to 10 of one-dimensional quasicrystals. Comparisons of the obtained sets of the necessary and sufficient conditions of one-dimensional quasicrystals with the corresponding ones of crystals are made, revealing that the phason fields, which characterize the quasicrystalline structure in any case, considerably influence the number as well as the degree of the obtained inequalities
Nanoporöse organische Gerüstverbindungen und Polymernetzwerke als feste molekulare Katalysatoren
No full textDiese Arbeit beschreibt die gezielte Entwicklung und Charakterisierung neuer poröser Materialien, die als feste molekulare Katalysatoren in verschiedenen Anwendungen getestet wurden. Zwei Materialklassen wurden synthetisiert und untersucht: poly-Imidazoliumsalze (pImBrs) und zinnhaltige vernetzte Gerüststrukturen (SnHCPs).
Die pImBrs wurden hinsichtlich ihrer Fähigkeit zur Carboxylierung und der damit verbundenen CO₂-Aktivierung sowie ihrer katalytischen Effizienz in der lösemittelfreien CCE-Reaktion (Cycloaddition von Kohlendioxid an Epoxiden) optimiert. Dabei zeigte sich, dass eine in situ-Carboxylierung die Ausbeute signifikant steigern kann.
Die SnHCPs wurden über eine skalierbare Syntheseroute hergestellt und als Katalysatoren für die Epimerisierung von Monosacchariden getestet. Im Vergleich zu konventionellen Materialien zeigen SnHCPs eine verbesserte katalytische Aktivität, höhere Reaktionsraten und Langzeitstabilität. Die Ergebnisse liefern eine Grundlage für die Weiterentwicklung poröser Katalysatoren und deren größerskalige Anwendung in nachhaltigen chemischen Prozessen
Aberrant choroid plexus formation drives the development of treatment-related brain toxicity
No full textBrain tumors are commonly treated with radiotherapy, but the efficacy of the treatment is limited by its toxicity to the normal tissue including post-irradiation contrast enhanced lesions often linked to necrosis. The poorly understood mechanisms behind such brain lesions were studied using cerebral organoids. Here we show that irradiation of such organoids leads to dose-dependent growth retardation and formation of liquid-filled cavities but is not correlated with necrosis. Instead, the radiation-induced changes comprise of an enhancement of cortical hem markers, altered neuroepithelial stem cell differentiation, and an increase of ZO1⁺/AQP1⁺/CLDN3⁺-choroid plexus (CP)-like structures accompanied by an upregulation of IGF2 mRNA, known to be expressed in CP and cerebrospinal fluid. The altered differentiation is attributed to changes in the WNT/BMP signaling pathways. We conclude that aberrant CP formation can be involved in radiation-induced brain lesions providing additional strategies for possible countermeasures
The ArtemIS project: Assessment for medium-depth geothermal energy utilization in Germany
No full textTo date, most geothermal projects in Germany have focused on deep geothermal systems, while resources at intermediate depths have only been explored to a small extend. However, medium-depth geothermal systems have a high potential for heat generation, even in areas previously considered less favorable for deep geothermal energy, and could make a significant contribution to Germany's heat supply. To accelerate the heat transition and to become independent of fossil fuels, the ArtemIS project aims to assess the medium-depth geothermal systems in Germany, covering all types of geological plays and providing regional information for different geothermal applications. Interactive heat transition profiles are being developed containing all relevant subsurface information required for preliminary geothermal assessment, such as geological descriptions of potential geothermal reservoirs, reservoir thickness, hydraulic and thermal rock properties, and fluid chemistry. In addition, static 3D geological models are being created as the basis for 3D numerical reservoir models using COMSOL Multiphysics to simulate the regional heat potential and different geothermal scenarios, including the performance of hydrothermal doublets. The investigation of well logs and core sample data of the Upper Maastrichtian Calcarenites in the North German Basin indicates a good geothermal potential, but notable lateral and vertical heterogeneities regarding reservoir thickness, grain size or glauconite content throughout the study area need to be considered during exploration. The first COMSOL simulation results highlight the impact of inter-well distance and reservoir thickness on operational parameters such as the occurrence time of thermal breakthrough and cooling rate in a multi-well array. Likewise, a 3D structural model of the Upper Rhine Graben was created and used to assess the regional heat supply, indicating a high potential for heat production in the sedimentary units at intermediate depths. The results of the ArtemIS project will be integrated into the publicly available web platform "Geothermal Information System – GeotIS", which will provide general information, data, and modelling results in a user-friendly way for non-professionals such as local communities and municipal energy suppliers
Magnetic and mechanical hardening of nano-lamellar magnets using thermo-magnetic fields
No full textHigh-performance magnetic materials based on rare-earth intermetallic compounds are critical for energy conversion technologies. However, the high cost and supply risks of rare-earth elements necessitate the development of affordable alternatives. Another challenge lies in the inherent brittleness of current magnets, which limits their applications for high dynamic mechanical loading conditions during service and complex shape design during manufacturing towards high efficiency and sustainability. Here, we propose a strategy to simultaneously enhance the magnetic and mechanical performance of a rare-earth-free multicomponent magnet. We achieve this by introducing nano-lamellar structures with high shape anisotropy into a cobalt–iron–nickel–aluminum material system through eutectoid decomposition under externally applied thermo-magnetic fields. Compared to the conventional thermally activated processing, the thermo-magnetic field accelerates phase decomposition kinetics, producing finer lamellae spacings and smaller eutectoid colonies. The well-tailored size, density, interface, and chemistry of the nano-lamellae enhance their pinning effect against the motion of both magnetic domain walls and dislocations, resulting in concurrent gains in coercivity and mechanical strength. Our work demonstrates a rational pathway to designing multifunctional rare-earth-free magnets for energy conversion devices such as high-speed motors and generators operating under harsh service conditions
CreepyCoCreator? Investigating AI Representation Modes for 3D Object Co-Creation in Virtual Reality
No full textGenerative AI in Virtual Reality offers the potential for collaborative object-building, yet challenges remain in aligning AI contributions with user expectations. In particular, users often struggle to understand and collaborate with AI when its actions are not transparently represented. This paper thus explores the co-creative object-building process through a Wizard-of-Oz study, focusing on how AI can effectively convey its intent to users during object customization in Virtual Reality. Inspired by human-to-human collaboration, we focus on three representation modes: the presence of an embodied avatar, whether the AI's contributions are visualized immediately or incrementally, and whether the areas modified are highlighted in advance. The findings provide insights into how these factors affect user perception and interaction with object-generating AI tools in Virtual Reality as well as satisfaction and ownership of the created objects. The results offer design implications for co-creative world-building systems, aiming to foster more effective and satisfying collaborations between humans and AI in Virtual Reality
Connecting process models to response times through Bayesian hierarchical regression analysis
No full textProcess models specify a series of mental operations necessary to complete a task. We demonstrate how to use process models to analyze response-time data and obtain parameter estimates that have a clear psychological interpretation. A prerequisite for our analysis is a process model that generates a count of elementary information processing steps (EIP steps) for each trial of an experiment. We can estimate the duration of an EIP step by assuming that every EIP step is of random duration, modeled as draws from a gamma distribution. A natural effect of summing several random EIP steps is that the expected spread of the overall response time increases with a higher EIP step count. With modern probabilistic programming tools, it becomes relatively easy to fit Bayesian hierarchical models to data and thus estimate the duration of a step for each individual participant. We present two examples in this paper: The first example is children’s performance on simple addition tasks, where the response time is often well predicted by the smaller of the two addends. The second example is response times in a Sudoku task. Here, the process model contains some random decisions and the EIP step count thus becomes latent. We show how our EIP regression model can be extended to such a case. We believe this approach can be used to bridge the gap between classical cognitive modeling and statistical inference and will be easily applicable to many use cases
Zellen sind Individualisten — Entscheidungsprozesse auf Einzelzellebene
No full textDecision-making is a fundamental aspect of life. However, our understanding of how cells encode and decode information to enable reliable fate decisions remains limited. Employing live cell imaging and automated analysis, our research unveils substantial heterogeneity in the cellular response to TGFβ and sheds light on the intricate link between the dynamics of SMAD signaling, the state of individual cells and their fate decisions
Interactive Input and Visualization for Planning with Temporal Uncertainty
No full textWhen planning series of events or processes, everyone has to cope with temporal uncertainty. Popular examples are holiday planning or train trips. There are several approaches to visualize temporal uncertainty when temporal data and events are already defined, but common research usually does not take uncertainty into account, neither as input nor output. To develop our design, we considered a variety of common approaches for uncertainty visualization and used participatory evaluation to validate our concept. Our design aims at using this uncertainty visualization while sketching the plan interactively. The user may draw and connect a variety of activities using different graphical metaphors as hints for uncertainty. The sketches are immediately interpreted and turned into a visualization to check and validate the resulting plan. To evaluate our new visualization and interactive approach, we conducted a quantitative user study. With an average correctness of 81%, the study shows that the visualization and interaction design work well together and that scheduling plans containing temporal uncertainties can be externalized by the majority of participants without major difficulties