24 research outputs found
The Wide Field Imager instrument for Athena
No full textESA's next large X-ray mission ATHENA is designed to address the Cosmic Vision science theme 'The Hot and Energetic Universe'. It will provide answers to the two key astrophysical questions how does ordinary matter assemble into the large-scale structures we see today and how do black holes grow and shape the Universe. The ATHENA spacecraft will be equipped with two focal plane cameras, a Wide Field Imager (WFI) and an X-ray Integral Field Unit (X-IFU). The WFI instrument is optimized for state-of-The-Art resolution spectroscopy over a large field of view of 40 amin x 40 amin and high count rates up to and beyond 1 Crab source intensity. The cryogenic X-IFU camera is designed for high-spectral resolution imaging. Both cameras share alternately a mirror system based on silicon pore optics with a focal length of 12 m and large effective area of about 2 m2at an energy of 1 keV. Although the mission is still in phase A, i.e. studying the feasibility and developing the necessary technology, the definition and development of the instrumentation made already significant progress. The herein described WFI focal plane camera covers the energy band from 0.2 keV to 15 keV with 450 Î1⁄4m thick fully depleted back-illuminated silicon active pixel sensors of DEPFET type. The spatial resolution will be provided by one million pixels, each with a size of 130 Î1⁄4m x 130 Î1⁄4m. The time resolution requirement for the WFI large detector array is 5 ms and for the WFI fast detector 80 Î1⁄4s. The large effective area of the mirror system will be completed by a high quantum efficiency above 90% for medium and higher energies. The status of the various WFI subsystems to achieve this performance will be described and recent changes will be explained here
La Tradición Clásica en la novela Phädra (1885) de Malwida von Meysenbug
No full textToday very few are familiar with Malwida von Meysenbug (1816-1903), andfewer still with her novel Phädra (1885). For this reason the present study, on the one hand,aims to recover and spread knowledge about the author and her rich literary output while,on the other hand, analyse the presence and treatment of Greco-Roman mythology in heronly work that is clearly based on Classical Tradition.Actualmente son muy pocos los que conocen a Malwida von Meysenbug (18161903), y menos todavía los que conocen su novela Phädra (1885). Por ello, el presente estudio pretende, por un lado, recuperar y difundir el conocimiento de la autora y su rica producción literaria y, por otro, analizar la presencia y el tratamiento de la mitología grecorromana en la que es su única obra de clara inspiración clásica
Total ionizing dose test with DEPFET sensors for Athena\u27s WFI
No full textThe focal plane of Athena\u27s WFI consists of spectroscopic single photon X-ray detectors that contain arrays of DEPFETs (DEpleted P-channel Field-Effect Transistor) as well as ASICs that are used for steering, readout and analog signal shaping. These components have to be examined regarding the effect of ionizing radiation. A Total Ionizing Dose (TID) test was done with prototype detector modules with 64x64 DEPFETs and one SWITCHER and VERITAS ASIC each. The current design of the WFI detector head features a proton shield equivalent to 4 cm of aluminum in order to prevent a strong increase of leakage current in the fully depleted 450 m thick bulk of the sensor. This keeps the expected doses and dose rates during the nominal mission relatively low (5 Gy). It is nevertheless important to study the current system in a dedicated TID test in order to exclude unforeseen effects and to study any radiation related changes that can have an effect on the very sensitive readout chain and the detector performance. The combination of low doses, low dose rates, low operating temperature (<-60°C) but high sensitivity on small changes of the threshold voltages represent somehow unusual boundary conditions in comparison to TID tests for standard radiation hard electronic components. Under these circumstances it was found beneficial to do the test in our own laboratory with an X-ray source in order to realize irradiation during nominal operation conditions. Furthermore, it facilitated to take annealing effects into account. Reasonably accurate dosimetry is achieved by measuring the X-ray spectrum and intensity with the device under test. After irradiation to a total dose of 14 Gy and subsequent annealing the threshold voltage of the DEPFETs were shifted by a mean value of 80 mV, the performance remained unchanged apart from a slight increase in readout noise by 10%.8 pages, 6 figures, to appear in SPIE Proceeding of Astronomical Telescopes + Instrumentation, 202
Regional Transport Aircraft with Regenerative Propulsion
No full textAE3200 - Design Synthesis ExerciseAerospace Engineerin
Potential for new railroad lines in Austria
No full textNachhaltiger Personenverkehr ist für die Erreichung der österreichischen Klimaziele ein wesentlicher Faktor. Insbesondere der Bahnverkehr, der allgemein eine gute CO2-Bilanz aufweist und mit CO2-freier Elektrizität betrieben werden kann, gewinnt an Bedeutung. Um dieses klimafreundliche Potenzial bestmöglich auszuschöpfen, gilt es nicht nur bestehende Strecken durch passende Intervalle und eine zeitgemäße Ausstattung zu optimieren, sondern auch neue Streckenpotenziale zu eruieren. Das Ziel der vorliegenden Arbeit ist daher die Identifikation von Teilflächen, die in Österreich noch nicht mit zukunftsfähiger Bahninfrastruktur ausgestattet sind. Zur Identifikation der Potenzialflächen für neue Eisenbahnstrecken wurde ein Modell entwickelt,um eine einheitliche Vorgehensweise zu definieren. Die Validierung dieses Modells ist ebenfalls Teil dieser Arbeit. Es werden die zentralen Forschungsfragen beantwortet, welche neuen Eisenbahnstrecken in Österreich das größte Potenzial haben und inwiefern das vorgestellte Rechenmodellzur Identifikation dieser geeignet ist. Die Forschungsmethodik ist durch einen 3-stufigen Prozess abgebildet. Ausgehend vom einheitlichen 500m-Raster im europäischen terrestrischen Referenzsystem, in der lambertschen Azimutalprojektion werden das Topografiepotenzial und das Fahrgastpotenzial in einem ersten Schritt bestimmt. Die Datengrundlage zu den Berechnungen speist sich aus frei zugängliche Beschäftigungs- und Bevölkerungsstatistiken. Danach werden die Einzelpotenziale zu einem Flächenpotenzial aggregiert und einer Klassifizierung von 1 bis 18 unterzogen, wobei der Wert 18 einer Zelle zugewiesen wird, die optimale Verhältnisse hinsichtlich der Topografie und der möglichen Fahrgäste aufweist. Die Aggregation wird einer Sensitivitätsanalyse unterzogen, um Auswirkungen in der Gewichtung von Topografie- und Fahrgastpotenzial bewerten zu können.Visualisierungen und Vergleiche des Flächenpotenzials mit der bestehenden Bahninfrastruktur und die sich daraus ergebenden Detailanalysen schließen die einheitliche Vorgehensweise ab.Die Forschungsergebnisse werden hinsichtlich möglicher Hauptbahnen, mit einer maximalen Steigung von 12,5‰, und Nebenbahnen, mit einer maximalen Steigung von 40‰, dargestellt.Die bundesweite Betrachtung der Flächenpotenziale, in Kombination mit der bestehenden Bahninfrastruktur,zeigt, dass insbesondere in den Ballungszentren anliegenden Bereichen Potenzial für weitere Schieneninfrastruktur gegeben ist. Beobachtet wird, dass an der Bundesgrenze zwischen Vorarlberg und der Schweiz weiteres Potenzial besteht. Für Hauptbahnen ergeben sich fünf und für Nebenbahnen zusätzlich zwei Analysebereiche, die im Detail bewertet werden. Die Umsetzungsnotwendigkeit wird anhand der Abdeckung mit den Flächen aus dem ÖV-Güteklassensystem berechnet. Für Hauptbahnen werden die Bereiche Krems Umgebung sowie Wien Ost als größte Potenzialflächen bewertet. Für Nebenbahnen können zusätzlich die Bereiche Salzburg Nord und Linz Süd als größte Potenzialflächen eingegrenzt werden. Das Rechenmodell besteht aus Fahrgast- und Topografiepotenzial. Die Treffsicherheit des Topografiepotenzials wird durch eine hohe Deckung mit dem aktuellen Streckennetz in Österreich bestätigt. Das Fahrgastpotenzial wird im Anschluss für Flächen mit Topografiepotenzial bewertet. Die aus dem Gesamtpotenzial identifizierten Analysebereiche werden mit Kennwerten miteinander verglichen, um eine Reihung der Umsetzungsnotwendigkeiten zu erhalten. Die standardisierte Vorgehensweise eignete sich demnach, Flächen für neue Bahnstrecken, unter Berücksichtigung der Veränderungen im Fahrgastpotenzial, zu identifizieren. Die vorliegende Diplomarbeit bietet eine Entscheidungsgrundlage für neue Bahninfrastrukturen und ein Instrument für eine ÖV-orientierte Raumplanung. Aufbauend auf den Ergebnissen dieser Diplomarbeit können länderübergreifende Analysebereiche untersucht und das Rechenmodell durch weitere öffentliche Datengrundlagen verfeinert werden.Sustainable passenger transport is an essential factor in achieving Austria’s climate targets. In particular, rail transport, which generally has an excellent carbon footprint and can be operated with CO2-free electricity, is gaining importance. In order to exploit this climate-friendly potential in the best possible way, it is necessary to optimize existing routes through suitable intervals and modern equipment and elicit new route potentials. Therefore, this study identifies areas in Austria with poor sustainable rail infrastructure.The thesis presents a model to identify potential areas for new railroad lines, aiming to define a uniform procedure. The validation of this model is also part of the work. Thus, the central research questions are answered, which areas in Austria have the most significant potential for new railroad lines, and to what extent the presented model is suitable for identifying these?A 3-step process represents the research methodology. Starting from a uniform 500m grid in the European terrestrial reference system, in the Lambertian azimuthal projection, the topography and passenger potential are determined in the first step. The database for the calculations is freely accessible and consists of employment, population statistics, and topographic data. The topography and passenger potentials are aggregated into an area potential and subjected to a classification of 1-18. The model assigns the value 18 to cells with optimal topography and potential ridership conditions. The aggregation is subjected to sensitivity analysis to evaluate impacts in the weighting of topography and ridership potential. Visualizations, comparisons of area potential with existing rail infrastructure, and the resulting detailed analyses conclude the unified approach. Different research results are presented for main lines, with a maximum gradient of 12,5‰, and secondary lines, with a maximum gradient of 40‰. The nationwide review of the area potentials combined with existing rail infrastructure shows potential for further rail infrastructure, especially in areas adjacent to the conurbations. Furthermore,the thesis reveals further potential at the national border between Vorarlberg and Switzerland. The author determines five analysis areas for main lines and additionally two areas for secondary lines. The need for implementation is calculated by comparing the analysis areas with the ÖV-Güteklassen. For main lines, the most significant potential areas are the surroundings of Krems and Vienna East. Salzburg North and Linz South were the most significant potential areas for secondary lines. The calculation model consists of passenger and topography potential. A coverage of 80% with the current route network in Austria confirms the accuracy of the topography potential. The passenger potential is exclusively evaluated for areas with topography potential. The analysis areas identified from the total potential are compared with each other using characteristic values in order to obtain a ranking of the need for implementation. Accordingly, the standardized approach was suitable for identifying areas for new railroad lines. The dynamic model considers changes in the data basis as well. This diploma thesis proposes a standardized and digital approach to enhance decision-making for new rail infrastructure and an instrument for transit-oriented development. Based on the results, cross-national analysis areas can be investigated, and other public databases can refine the calculation model
Electrical characterization of prototype DEPFET detectors for Athena's Wide Field Imager
No full textThe Wide Field Imager (WFI), one of two complementary instruments on board ESA's next large X-ray mission Athena, combines state-of-the-art resolution spectroscopy with a large field of view and high count rate capability. Centerpiece of the WFI instrument are four DEPFET (Depleted p-channel field effect transistor) sensors with a size of 512_512 pixels each and one fast detector with a size of 64_64 pixels. They are planned to be operated in drain current readout mode, which enables fast readout rates but is sensitive to inhomogeneities of the drain currents. These inhomogeneities arise from the sheer size of the DEPFET sensor matrix and are originated in the spatial distribution of wafer properties and process parameters. We characterized the drain current distribution of a prototype device (64_64 pixels) utilizing the same layout and technology as specified for the pre-flight production of Athena's WFI DEPFET detectors. In order to better understand the origin of the current spread we measured I-V characteristics of all pixels and extracted threshold voltages and transconductance values of the detector in operational conditions. This is enabled by features of the VERITAS read-out ASIC
Low temperature proton irradiation with DEPFETs for Athena\u27s Wide Field Imager
No full textThe Wide Field Imager (WFI), one of two instruments on ESA\u27s next large X-ray mission Athena, is designed for imaging spectroscopy of X-rays in the range of 0.2 to 15 keV with a large field of view and high count rate capability. The focal plane consists of back-illuminated DEPFET (Depleted p-channel field effect transistor) sensors that have a high radiation tolerance and provide a near Fano-limited energy resolution. To achieve this, a very low noise readout is required, about 3 electrons ENC at beginning of life is foreseen. This makes the device very susceptible to any radiation induced worsening of the readout noise. The main mechanism of degradation will be the increase of dark current due to displacement damage caused primarily by high energy protons. To study the expected performance degradation, a prototype detector module with fully representative pixel layout and fabrication technology was irradiated with 62.4 MeV protons at the accelerator facility MedAustron in Wiener Neustadt. A total dose equivalent to 3.3 10-MeV protons/ was applied in two steps. During, in-between and after the irradiations the detector remained at the operating temperature of 213 K and was fully biased and operated. Data was recorded to analyze the signal of all incident particles. We report on the increase of dark current after the irradiation and present the current related damage rate at 213 K. The effect of low temperature annealing at 213 K , 236 K, 253 K, 273 K, and 289 K is presented.to be published in SPIE Proceeding of Astronomical Telescopes + Instrumentation, 202
