129 research outputs found

    RF-Separated Beam Project for the M2 Beam Line at CERN

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    Within the framework of the Physics Beyond Colliders initiative at CERN, discussions are underway on the feasibility of producing radio-frequency (RF) separated beams for Phase-2 of the AMBER experiment at the M2 beam line in the North experimental area of the CERN SPS. The technique of RF separation is applied to enrich the content of a certain particle type within a beam consisting of different species at the same momentum. It relies on the fact that each particle type has a different velocity, decreasing with rest mass. The successor of the COMPASS experiment, AMBER, requires for its Phase-2 measurements high-intensity, high-purity kaon (and antiproton) beams, which cannot be delivered with the currently existing conventional M2 beam line. The present contribution introduces the principle of RF separation and explains its dependence on different parameters of beam optics and hardware. The first examination of potential showstoppers for the RF-separated beam implementation is presented, based on the particle production rates, beam line transmission for specific optics settings, limitations for overall beam intensity and purity posed by beam line acceptance and radiation protection. Different beam optics settings have been examined, providing either focused or parallel beams inside the RF cavities. The separation and transmission capability of the different optics settings for realistic characteristics of RF cavities are discussed and the preliminary results of the potential purity and intensity of the RF-separated beam are presented. They illustrate the high importance of an RF-separated kaon beam for many of the AMBER Phase-2 data taking programs, such as spectroscopy, prompt-photon production, Primakoff reactions and kaon charge-radius measurement

    Festschrift anläßlich der Emeritierung von Prof. Dr.-Ing. Walter Raab

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    Festschrift zum Festkolloquium am 8. April 1994 anläßlich der Emeritierung von Herrn Prof. Dr.-Ing. Walter Raab, Leiter des Fachgebiets Maschinenlemente und Mechanik an der Technischen Hochschule Darmstadt

    Durchflusskennwerte und Querbauwerke: Leitfaden zur Web-Anwendung „Ausgewählte Durchflusskennwerte und Querbauwerke sächsischer Fließgewässer, Stand 2015“

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    Der Leitfaden informiert über Methodik und Ergebnisse der Regionalisierung von ausgewählten Durchflusskennwerten. Über die Internet-Anwendung »Durchflusskennwerte und Querbauwerke« können für beliebige Querschnitte der sächsischen Fließgewässer die Durchflusskennwerte abgefragt werden (Stand 2015). Die Kennwerte werden u. a. benötigt bei der Ermittlung von Mindestwasserführungen und mittleren Durchflussdargeboten sowie bei der Planung wasserbaulicher Anlagen und der Ausweisung von Überschwemmungsgebieten. Die Publikation richtet sich an Wasserbehörden und Planungsbüros, aber auch an Gewässernutzer in Sachsen. Redaktionsschluss: 21.06.201

    Commissioning of the vacuum system of the KATRIN Main Spectrometer

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    The KATRIN experiment will probe the neutrino mass by measuring the beta-electron energy spectrum near the endpoint of tritium beta-decay. An integral energy analysis will be performed by an electro-static spectrometer (Main Spectrometer), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m^3, and a complex inner electrode system with about 120000 individual parts. The strong magnetic field that guides the beta-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300{\deg}C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10^{-11} mbar range. It is demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016.Comment: submitted for publication in JINST, 39 pages, 15 figure

    Commissioning of the vacuum system of the KATRIN Main Spectrometer

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    The KATRIN experiment will probe the neutrino mass by measuring the beta-electron energy spectrum near the endpoint of tritium beta-decay. An integral energy analysis will be performed by an electro-static spectrometer (Main Spectrometer), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m^3, and a complex inner electrode system with about 120000 individual parts. The strong magnetic field that guides the beta-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300{\deg}C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10^{-11} mbar range. It is demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016

    Muscle precursor cells in the developing limbs of two isopods (Crustacea, Peracarida): an immunohistochemical study using a novel monoclonal antibody against myosin heavy chain

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    In the hot debate on arthropod relationships, Crustaceans and the morphology of their appendages play a pivotal role. To gain new insights into how arthropod appendages evolved, developmental biologists recently have begun to examine the expression and function of Drosophila appendage genes in Crustaceans. However, cellular aspects of Crustacean limb development such as myogenesis are poorly understood in Crustaceans so that the interpretative context in which to analyse gene functions is still fragmentary. The goal of the present project was to analyse muscle development in Crustacean appendages, and to that end, monoclonal antibodies against arthropod muscle proteins were generated. One of these antibodies recognises certain isoforms of myosin heavy chain and strongly binds to muscle precursor cells in malacostracan Crustacea. We used this antibody to study myogenesis in two isopods, Porcellio scaber and Idotea balthica (Crustacea, Malacostraca, Peracarida), by immunohistochemistry. In these animals, muscles in the limbs originate from single muscle precursor cells, which subsequently grow to form multinucleated muscle precursors. The pattern of primordial muscles in the thoracic limbs was mapped, and results compared to muscle development in other Crustaceans and in insects

    Gamma-induced background in the KATRIN main spectrometer

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    International audienceThe KArlsruhe TRItium Neutrino (KATRIN) experiment aims to make a model-independent determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c 2 . It investigates the kinematics of β -particles from tritium β -decay close to the endpoint of the energy spectrum. Because the KATRIN main spectrometer (MS) is located above ground, muon-induced backgrounds are of particular concern. Coincidence measurements with the MS and a scintillator-based muon detector system confirmed the model of secondary electron production by cosmic-ray muons inside the MS. Correlation measurements with the same setup showed that about 12% of secondary electrons emitted from the inner surface are induced by cosmic-ray muons, with approximately one secondary electron produced for every 17 muon crossings. However, the magnetic and electrostatic shielding of the MS is able to efficiently suppress these electrons, and we find that muons are responsible for less than 17% (90% confidence level) of the overall MS background
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