Publications (7)1.45 Total impact
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Article: Detection system for forward emitted photons at the Experimental Storage Ring at GSI
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ABSTRACT: A single photon counting system has been developed for efficient detection of forward emitted fluorescence photons at the Experimental Storage Ring (ESR) at GSI. The system employs a movable parabolic mirror with a central slit that can be positioned around the ion beam and a selected low noise photomultiplier for detection of the collected photons. Compared to the previously used system of mirror segments installed inside the ESR the collection efficiency for forward-emitted photons is improved by more than a factor of 5. No adverse effects on the stored ion beam have been observed during operation besides a small drop in the ion current of about 5% during movement of the mirror into the beam position. The new detection system has been used in the LIBELLE experiment at ESR and enabled for the first time the detection of the ground-state hyperfine M1 transition in lithium-like bismuth (209Bi80+) in a laser-spectroscopy measurement.05/2013; -
Article: Limits on the release of Rb isotopes from a zeolite based 83mKr calibration source for the XENON project
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ABSTRACT: The isomer 83mKr with its half-life of 1.83 h is an ideal calibration source for a liquid noble gas dark matter experiment like the XENON project. However, the risk of contamination of the detector with traces of the much longer lived mother isotop 83Rb (86.2 d half-life) has to be ruled out. In this work the release of 83Rb atoms from a 1.8 MBq 83Rb source embedded in zeolite beads has been investigated. To do so, a cryogenic trap has been connected to the source for about 10 days, after which it was removed and probed for the strongest 83Rb gamma-rays with an ultra-sensitive Germanium detector. No signal has been found. The corresponding upper limit on the released 83Rb activity means that the investigated type of source can be used in the XENON project and similar low-background experiments as 83mKr generator without a significant risk of contaminating the detector. The measurements also allow to set upper limits on the possible release of the isotopes 84Rb and 86Rb, traces of which were created alongside the production of 83Rb at the Rez cyclotron.09/2011; -
Article: Prototype of an angular-selective photoelectron calibration source for the KATRIN experiment
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ABSTRACT: The method of direct neutrino mass determination based on the kinematics of tritium beta decay, which is adopted by the KATRIN experiment, makes use of a large, high-resolution electrostatic spectrometer with magnetic adiabatic collimation. In order to target a sensitivity on the neutrino mass of 0.2 eV/c^2, a detailed understanding of the electromagnetic properties of the electron spectrometer is essential, requiring comprehensive calibration measurements with dedicated electron sources. In this paper we report on a prototype of a photoelectron source providing a narrow energy spread and angular selectivity. Both are key properties for the characterisation of the spectrometer. The angular selectivity is achieved by applying non-parallel strong electric and magnetic fields: Directly after being created, photoelectrons are accelerated rapidly and non-adiabatically by a strong electric field before adiabatic magnetic guiding takes over.11/2010; -
Article: A Contact-Less 2-Dimensional Laser Sensor for 3-Dimensional Wire Position and Tension Measurements
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ABSTRACT: We have developed a contact-less two-dimensional laser sensor which combines position and tension measurements of wires with a diameter of order 0.2 mm. The sensor consists of commercially available laser pointers, lenses, color filters and photodiodes. In our application we have used this laser sensor in conjunction with an automated three-dimensional coordinate measuring machine (CMM). The device allows for a position measurement of wires in three dimensions with an accuracy of about 10 ¿m. At the same time the wire tension can be determined with an accuracy of 0.04 N. The device is operated at a distance of 150 mm from the wire. For each position measurement, the laser sensor is moved by the automated CMM into a plane, where the coordinates at which the wires intersect with this plane are determined. The position of the plane itself (the third coordinate) is given by the third axis of the CMM which is perpendicular to this plane. The precision of the device was determined using stainless steel wires with a diameter of 0.2 mm and a tension of 5 N. We use the sensor for quality assurance of the wire electrode modules for the KATRIN neutrino mass experiment. These modules are comprised of two layers of wires, which are 70 mm apart. In general, the device presented here is well suited for the measurement of any complex wire chamber geometry.IEEE Transactions on Nuclear Science 05/2010; · 1.45 Impact Factor -
Article: Effect of a sweeping conductive wire on electrons stored in the Penning trap between the KATRIN spectrometers
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ABSTRACT: The KATRIN experiment is going to search for the mass of the electron antineutrino down to 0.2 eV/c^2. In order to reach this sensitivity the background rate has to be understood and minimised to 0.01 counts per second. One of the background sources is the unavoidable Penning trap for electrons due to the combination of the electric and magnetic fields between the pre- and the main spectrometer at KATRIN. In this article we will show that by sweeping a conducting wire periodically through such a particle trap stored particles can be removed, an ongoing discharge in the trap can be stopped, and the count rate measured with a detector looking at the trap is reduced. Comment: Final version published in EPJ A, 14 pages, 19 figures (21 files)09/2009; -
Article: Contactless 2-dimensional laser sensor for 3-dimensional wire position and tension measurements
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ABSTRACT: We have developed a contact-free 2-dimensional laser sensor with which the position of wires can be measured in 3 dimensions with an accuracy of better than 10 micrometer and with which the tension of the wires can be determined with an accuracy of 0.04 N. These measurements can be made from a distance of 15 cm. The sensor consists of commercially available laser pointers, lenses, color filters and photodiodes. In our application we have used this laser sensor together with an automated 3 dimensional coordinate table. For a single position measurement, the laser sensor is moved by the 3-dimensional coordinate table in a plane and determines the coordinates at which the wires intersect with this plane. The position of the plane itself (the third coordinate) is given by the third axis of the measurement table which is perpendicular to this plane. The control and readout of the table and the readout of the laser sensor were realized with LabVIEW. The precision of the position measurement in the plane was determined with wires of 0.2 mm and 0.3 mm diameter. We use the sensor for the quality assurance of the wire electrode modules for the KATRIN neutrino mass experiment. We expect that the precision is at least comparable or better if the wires are thinner. Such a device could be well suited for the measurement of wire chamber geometries even with more than one wire layer. Comment: 15 pages, 8 figures07/2009; -
Article: Effect of a sweeping conductive wire on electrons stored in a Penning-like trap between the KATRIN spectrometers
http://dx.doi.org/10.1140/epja/i2010-10959-1.
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Institutions
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2011
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Westfälische Wilhelms-Universität Münster
Münster, North Rhine-Westphalia, Germany
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