Freiburg 2008 – scientific programme
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T: Fachverband Teilchenphysik
T 88: Niederenergie-Neutrinophysik und Suche nach Dunkler Materie III
T 88.7: Talk
Wednesday, March 5, 2008, 18:20–18:35, KGI-HS 1098
Penning discharge in the KATRIN pre-spectrometer — •Ferenc Glück1, Lutz Bornschein1, Florian Fränkle1, Florian Habermehl1, Karen Hugenberg2, Michelle Leber3, Kathrin Valerius2, and Christian Weinheimer2 for the KATRIN collaboration — 1Universität Karlsruhe — 2Universität Münster — 3University of Washington, Seattle
The KATRIN pre-spectrometer is a MAC-E filter (electrostatic spectrometer with magnetic adiabatic collimation), with the purpose of reducing the background in the KATRIN neutrino mass experiment. Various investigations conducted in winter 2006-2007 showed the presence of strong Penning discharges, exhibiting increase of pressure inside of the pre-spectrometer and of power supply leakage current, even for rather small tank potential and magnetic field. Calculations showed the presence of deep Penning traps at the two end-regions of the pre-spectrometer, close to the ground electrodes. Experiments indicated a clear correlation between the deepness of the Penning traps and the strength of the discharge; using electrode configurations without Penning traps no discharge was observed. In order to get rid of the deep Penning traps, new shielding electrodes were designed, constructed and installed into the spectrometer. According to the recent experiments, the presence of these electrodes completely solved the Penning discharge problem. The experiences obtained with the pre-spectrometer are very important in order to avoid Penning discharges inside the KATRIN main spectrometer and at the detector system.