Bonn 2010 – wissenschaftliches Programm
HK 36.83: Poster
Mittwoch, 17. März 2010, 14:00–16:00, HG Aula
Electromagnetic design of the pump port region of the KATRIN main spectrometer — Michael Zacher, Sebastian Vöcking, Christian Weinheimer, and •Matthias Dropmann — Institut für Kernphysik, Universität Münster
The KArlsruher TRItium Neutrino experiment aims to measure the mass of the electron neutrino. This is done by measuring the endpoint region of the Tritium-β-decay with high precision. The main spectrometer has a length of 20 meters and utilizes magnetic adiabatic collimation combined with an electrostatic filter (MAC-E type spectrometer). This leads to a sensitivity for the neutrino mass of mνe ≤ 0,2eV with 90% C.L..
To reach the desired sensitivity, a small background rate in the main spectrometer is needed. Thus an inner electrode system, which is on a slightly more negative potential than the vessel hull, is introduced to shield electrons ejected e.g. by cosmic muons from the tank material. Although the electric fields are mainly shaped by the electrodes, they are still influenced by the vessel potential. Due to the desired ultra high vacuum conditions inside the spectrometer, there are elliptic pump ports with dimensions of 1.68x2.22 meters. Therefore the electric fields are misaligned in these regions. This can be corrected by introducing a wire grid at the pump port to cover the opening without affecting the pumping functionality of the port.
This work is supported by BMBF under contract number 05A08PM1.