102,046 research outputs found
Internal charge injection for the calibration of DEPFETs with non-linear amplification
No full textWithin the DSSC (DEPFET Sensor with Signal Compression) project a new active pixel sensor based on a Depleted P-Channel Field Effect Transistor (DEPFET) has been developed for the use at the European X-ray Free Electron Laser (EuXFEL). A DEPFET is an integrated detector amplifier combining internal amplification, full sensitivity over the whole bulk thickness, analog data storage, readout on demand, low serial noise, and absence of reset noise. To cope with the EuXFEL detector requirements the new developed DSSC-DEPFET has a non-linear amplification, i.e. a high gain for small signals in order to provide single photon resolution of low energy X-rays and a reduced gain for large signals to have a high dynamic range of several thousand photons per pixel and frame. For a pixel by pixel calibration of the final DSSC system the new feature of internal charge injection in every pixel has been introduced and investigated in detail using existing DSSC-prototype structures. This paper illustrates the principle of the injection mechanism and demonstrates its capability for calibration purposes
Methods for calibrating the gain and offset of the DSSC detector for the European XFEL using X-ray line sources
No full textThe DSSC (DEPFET Sensor with Signal Compression) will be a silicon based, 2d 1 Mpx imaging detector for the European X-ray Free Electron Laser Facility (XFEL.EU) in Hamburg, Germany. The DSSC is foreseen for soft X-radiation from 0.5 keV up to 6 keV. Driven by its scientific requirements, the design goals of the detector system are single photon detection, high dynamic range and a high frame rate of up to 4.5 MHz. Signal compression and amplification will be performed in the silicon sensor pixels yielding a low signal noise. Utilizing an in-pixel active filtering stage and an 8/9-bit ADC, the detector will provide parallel read-out of all pixels. In order to calibrate offset and gain, the procedure currently under investigation relies on determining peak positions in measurements with calibration line sources such as 55Fe. Here the status of studies of the stability and performance of a parameterized fit function designed for this task will be presented
Methods for calibrating the gain and offset of the DSSC detector for the European XFEL
No full textThe DEPFET Sensor with Signal Compression (DSSC) will be a 2d 1Mpx imaging detector for the European X-ray Free Electron Laser facility (XFEL.EU), that is currently under construction in Hamburg. The DSSC is foreseen as a photon counting detector for soft X-ray radiation from 0.5 keV up to 6 keV. Driven by its scientific requirements, the design goals of the detector system are foremost low noise, a high dynamic range and a high frame rate of up to 4.5 MHz. Signal compression, amplification and digitization will be performed in the focal plane. Utilizing an in-pixel active filtering stage and an 8/9-bit ADC, the detector will provide parallel readout of all pixels. A critical step of calibrating the detector is the determination of the system gain and offset based on peak energies of X-ray calibration line sources such as 55 Fe. This is demanding due to the intrinsically low spectral resolution of the DSSC. The results of studies on the stability and performance of automated procedures for peak fitting in single pixel spectra with a low energy resolution were presented on a poste
Calibration Sources and Techniques for Large Format X-Ray Imagers at XFEL
No full textIn this work we compare different calibration sources and focus on their combination to optimize the calibration of large-format X-ray imagers over a wide range. This activity is carried out in the framework of the DSSC project and the primary aim is the calibration of the DSSC camera. We considered pulsed IR laser, radioactive sources, X-ray tube, electrical injection devices, X-ray synchrotron beam, low-energy protons, LED sources. The relevant features (deposited energy and pulse width) are critically summarized and calibration strategies will be discussed
Study of Systematic and Statistical Uncertainty in Offset, Noise, and Gain Determination of the DSSC Detector for the European XFEL
No full textThe DSSC (DEPFET Sensor with Signal Compression) is a new instrument with non-linear response and parallel signal processing (filtering, linear amplification, and 8-bit digitization) for all pixels. The DSSC will serve as ultra-fast megapixel imaging detector at the European XFEL (X-ray Free Electron Laser) in Schenefeld, Germany, which began science operation in September this year. The DSSC detector needs to be calibrated for each of a set of twelve predefined operation modes before being employed in scientific experiments. A crucial step in the calibration of the response of each individual detector pixel is the calibration of offset and gain. We present a study of both systematic and statistical uncertainty in the determination of offset, noise, and gain. The best possible calibration of offset and gain requires that these two quantities can be determined with an uncertainty that is less than half the finite resolution of the respective read-out ASIC calibration settings. The study is based on simulated calibration data, which were then analyzed using our calibration tools. Systematic and statistical uncertainty in offset, noise, and gain determination was quantified by comparing analysis results with the actual values employed in the simulations. A review of all results identified the most suitable calibration approaches. Their ability for providing the best possible offset and gain calibration is discussed
Validation of Proton Tests in Air for Detector Calibration over a Wide Range of Charge Injection Levels
No full textWe successfully evaluated the possibility of using a pulsed monoenergetic proton beam as a diagnostic tool for semiconductor detectors' response mapping at high charge densities. In order to ease the setup of the detector under test we explored the opportunity of performing tests with protons in air. We qualified a polyimide film window (Upilex-S, 7.5 mu m nominal thickness) as proton extraction window and the energy loss in air as a function of distance. The tests have been carried out in vacuum first, in order to evaluate the energy loss due to the window only, followed by in-air tests aimed at the investigation of the total energy degradation of the extracted proton beam
Study of charge collection effects in the DSSC sensor
No full textThe DePFET Sensor with Signal Compression (DSSC) instrument is a 1 Mpixel camera under development at the European XFEL for the detection of low-energy X-rays (<;6 keV). In this work an experimental study of charge collection effects has been carried out as a function of the deposited charge in order to extract the true time profile of the collected charge cloud in a wide range of experimental conditions. A preliminary set of results is presented and discussed
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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