100 research outputs found
Software and hardware development for the liquid scintillator detector OSIRIS of the JUNO experiment
No full textThe Jiagmen Underground Neutrino Observatory (JUNO) is a next-generation liquid scintillator (LS) neutrino experiment currently under construction near Kaiping, Southern China. The construction of JUNO will end in 2024. JUNO will accomplish its main goal with six years of data-taking: the determination of the neutrino mass ordering with a sensitivity of 3-4 . To achieve this goal, the LS used in JUNO must meet stringent requirements regarding its radiopurity. For validation of these requirements during the months-long filling of JUNO, the Online Scintillator Internal Radioactivity System (OSIRIS) monitors the LS radiopurity via Bi-Po / Bi-Po coincident decays in the respective decay chains of U and Th. In OSIRIS, German workgroups have a leading role. This thesis presents contributions to the development of both hardware and software for OSIRIS. The hardware-focused part of the thesis details the author's construction of an ultrapure-water-based cleaning facility at RWTH Aachen as well as the design of a holder structure for OSIRIS's photomultiplier tubes (PMTs). The cleaning facility was used successfully to prepare many German working groups' contributions prior to their shipment to China. The holder development was aided by simulations based on finite element analysis. Both holder design requirements and simulation results were confirmed in load tests of the holder structure, first at RWTH and later again on-site at JUNO in 2022. The holder as originally planned for the intelligent PMT system (iPMT) had to be adapted at JUNO to accommodate the Chinese Large PMT system (LPMT), because the iPMTs were found to be non-functional upon arrival at JUNO. During the on-site mission in 2022, also studies of airborne and surface dust levels within the OSIRIS detector were carried out by the author. The investigations proved that a) OSIRIS's air filtration unit maintained the required ISO-7 clean room environment and b) the accumulated dust on OSIRIS's central vessel was uncritical for the experiment's future. The measurements also showed a substantial decrease in surface particle counts after a subsequent detector cleaning. The commissioning of one of OSIRIS's calibration systems, the Automated Calibration System (ACU), was supervised by the author in 2023 as another part of the hardware-related work described here. The ACU contains a radioactive multi-gamma source (Cs/Zn/Co) and a 435 nm LED to perform calibrations of LPMT timing and charge as well as calibrations of detector energy and vertex reconstructions. A K-source serves as a standard candle during normal operation and is used to monitor the optical properties of the LS. During the ACU commissioning, the ACU hardware and software, the related safety mechanisms, and the positioning of the sources were evaluated. In the positioning calibrations, a precision of 4 mm was achieved, which is well below the sub-cm requirement of OSIRIS. Overall, the results of the commissioning successfully prepared the ACU for nominal operation in OSIRIS. The calibration of OSIRIS with the ACU was also the key aspect of the software-focused part of the thesis. The presented GEANT4-based energy calibration studies improved the analysis algorithms in terms of stability and speed, while also determining a minimal statistic of 30k events needed for each of the involved radioactive isotopes to reach required precision levels. The analyses of different source capsule designs validated their usability in OSIRIS and led to an approval for the calibration source production in late 2022. Also a first set of ACU calibration data, recorded with the LED of the ACU, was analysed by the author. The analysis focused on evaluating the overall detector performance and identified irregularities for PMTs close to the LED cable, promptly triggering investigations by the OSIRIS group. The analysis also confirmed both the principle of aligning the PMT timings and the expected detector behaviour for different illumination levels
OSIRIS - The Online Scintillator Internal Radioactivity Investigation System of JUNO
No full textThe 20 kton liquid scintillator detector of the Jiangmen Neutrino Underground Observatory, currently under construction in Southern China, has a vast potential for new insights into various fields of (astro-)particle physics. Stringent limits on the liquid scintillator radiopurity are required for several physics goals of JUNO. For both Th and U, a radiopurity of 10 g/g is required for reactor antineutrino measurements, 10 g/g for solar neutrino measurements. An independent detector, the Online Scintillator Internal Radioactivity Investigation System (OSIRIS), will be used to ensure these limits are kept. This talk will present OSIRIS and its sensitivity to Th and U in detail.OSIRIS allows an online radiopurity evaluation of the scintillator during the months-long filling of JUNO. The design of OSIRIS is optimized for tagging fast Bi-Po and Bi-Po coincidence decays in the decay chains of U and Th, respectively. The coincident decay signatures and their rates offer a potent background rejection as well as a direct translation into U-/Th-abundances in the scintillator. OSIRIS will also be able to measure the levels of C in the scintillator, down to a C/C ratio of 10 at 90\% C.L. Furthermore, the level of Po and a possible contamination by Kr can be determined. To achieve its goals, OSIRIS features a water-submerged 20 ton liquid scintillator target monitored by 76 intelligent PMTs (iPMTs). The novel design of the iPMTs allows a triggerless readout scheme with high signal quality. A single computer is sufficient to process the data stream into events for further analysis. The timing and charge calibration of the iPMTs will be performed with Laser- and LED-based systems. The energy and vertex reconstructions will utilise height-adjustable radioactive sources within the liquid scintillator
Dallmann, Christine/Hartung-Griemberg, Anja/Aigner, Alfons/Buchele, Kai-Thorsten (Hrsg.) (2018). Comics. Interdisziplinäre Perspektiven aus Theorie und Praxis auf ein Stiefkind der Medienpädagogik. München: kopaed. 280 S., 20 €
No full textDallmann, Christine/Hartung-Griemberg, Anja/Aigner, Alfons/Buchele, Kai-Thorsten (Hrsg.) (2018). Comics. Interdisziplinäre Perspektiven aus Theorie und Praxis auf ein Stiefkind der Medienpädagogik. München: kopaed. 280 S., 20 €.
Comics begeistern schon seit jeher Kinder und Jugendliche. Dennoch wurden sie aus wissenschaftlicher Perspektive bisher kaum beachtet. Die Festschrift Comics, anlässlich des 60. Geburtstags von Ralf Vollbrecht, Erziehungswissenschaftler, Medienpädagoge und Hochschullehrer an der Technischen Universität Dresden, unternimmt den Versuch, sich der Mediengattung aus verschiedenen Perspektiven zu nähern und Einblicke in das Genre zu gewähren.
Da der Themenkomplex ‚Comics in Deutschland‘ von Grund auf bearbeitet wurde, beschäftigen sich verschiedene Beiträge wiederholt mit der historischen Entwicklung des Mediums. Inhaltsanalysen und eine Auseinandersetzung mit Körperdarstellungen in Comics, angefertigt von Ralf Vollbrecht, zeigen zudem die verschiedenen Ausprägungen der Kunstform auf. Die abgedruckten Wortbeiträge, die unter anderem die Bedeutung von Comics in Jugendkulturen veranschaulichen, werden durch eine empirische Studie und die Vorstellung eines Forschungsprojekts zur kindlichen Aneignungspraxis vertieft. Zudem verdeutlicht ein Abriss über kommunikations- und medienwissenschaftliche, aber auch medienpädagogische Auseinandersetzungen die Ergiebigkeit von Comics in den verschiedenen Fachbereichen, die insbesondere auch an Vollbrechts Forschungsschwerpunkten anknüpfen. Hierauf werden Verbindungen zur medienpädagogischen Praxis hergestellt und insbesondere Darstellungsformen, wie Film, Computerspiele und Kunst unter medienpädagogischen Gesichtspunkten beachtet.
Comics stellt durch eine bunte Mischung an Beiträgen immer wieder gelungene Bezüge zum wissenschaftlichen Wirken Ralf Vollbrechts wie auch zu seiner persönlichen Leidenschaft ‚Comic\u27 her, die zugleich zahlreiche Anregungen für die medienpädagogische Forschung und Praxis bieten. So wird den Lesenden nicht nur Information vermittelt, sondern nachhaltiges Interesse am Bereich Comics geweckt. Comics räumt mit Vorbehalten gegenüber dem Genre auf und verdeutlicht durch anschauliche Beispiele ihr medienpädagogisches Potenzial. Es wird nicht nur der Stellenwert des Mediums deutlich, sondern auch die Bandbereite an Möglichkeiten für eine fundierte wissenschaftliche Auseinandersetzung aus medienpädagogischer Perspektive aufgezeigt. So werden auch alle Lesenden, die bisher noch wenige Berührungspunkte mit der Medienpädagogik hatten, durch eine allgemeine Einleitung in das medienpädagogische Feld abgeholt. l
OSIRIS – An online scintillator radiopurity monitor for the JUNO experiment
No full textThe Jiangmen Underground Neutrino Observatory (JUNO) currently under construction in China, will be the first multi-kton liquid scintillator detector and has a vast potential for new insights into several fields of neutrino and astroparticle physics. To reach its design sensitivity for detecting reactor and solar neutrinos, a radiopure liquid scintillator is required. For IBD measurements, a radiopurity of 10 g/g is needed for both U and Th, 10 g/g for solar measurements.The Online Scintillator Internal Radioactivity Investigation System (OSIRIS) allows an on-line radiopurity evaluation of the scintillator during the JUNO detector filling over several months. The design of OSIRIS is optimized for tagging Bi-Po and Bi-Po coincidence decays in the decay chains of U and Th, respectively. OSIRIS will also be able to monitor the C and Po levels in the scintillator.To achieve its goals, OSIRIS features a 20 ton liquid scintillator target monitored by 76 intelligent photomultiplier tubes (iPMTs). In this novel design, each iPMT consists of a PMT and its readout electronics mounted on its back. Each hit causing these electronics to trigger is sent to the DAQ as a digitized PMT pulse. A single computer (EventBuilder) is sufficient to combine the data stream into events for further analysis.For the timing and charge calibration of the detector, two optical systems (LED- and LASER-based) are employed. The energy and position calibration of OSIRIS is performed with height-adjustable radioactive sources within the liquid scintillator. These sources cover the crucial energy range for the detection of Bi-Po signals between 0.66 MeV to 2.5 MeV.The general design of the OSIRIS detector and its subsystems is presented in this poster
Concepts of “Filmbildung“ (film education) and educational aversion to the visual sense
No full textGängige Konzepte der Filmbildung werden vorgestellt und in ihren pädagogischen Implikationen diskutiert. Dabei wird kritisch auf das Kanon-Konzept eingegangen sowie auf den vom Autor favorisierten Ansatz, Spielfilme auch als Gegenstand einer narrativen Pädagogik zu verstehen. (DIPF/Orig.)Common concepts of film education are presented and discussed in their pedagogical implications. In particular, the canon concept is presented as well as the approach favored by the author to understand films as a subject of a narrative educational theory. (DIPF/Orig.
Konzepte der Filmbildung und der pädagogische Widerwille gegen den Seh-Sinn: Concepts of “Filmbildung“ (film education) and educational aversion to the visual sense
No full textGängige Konzepte der Filmbildung werden vorgestellt und in ihren pädagogischen Implikationen diskutiert. Dabei wird kritisch auf das Kanon-Konzept eingegangen sowie auf den vom Autor favorisierten Ansatz, Spielfilme auch als Gegenstand einer narrativen Pädagogik zu verstehen.Common concepts of film education are presented and discussed in their pedagogical implications. In particular, the canon concept is presented as well as the approach favored by the author to understand films as a subject of a narrative educational theory
Notes and Documents
No full textNotes and Documents section for Volume 70, Number 3, Fall 1992. It includes a document by the author of a previous article in The Chronicles Spring 1991 issue about lost findings from the Braden Site of the collection being returned to the Oklahoma Museum of Natural History
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