Mainz 2014 – scientific programme
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T: Fachverband Teilchenphysik
T 116: Niederenergie-Neutrinophysik 5
T 116.8: Talk
Thursday, March 27, 2014, 18:30–18:45, P106
Background due to secondary electron emission in the KATRIN experiment — •Ferenc Glück and Benjamin Leiber for the KATRIN collaboration — Karlsruhe Institute of Physics, IKP and IEKP
The aim of the KATRIN experiment is to determine the absolute neutrino mass scale in a model independent way, by measuring the electron energy spectrum shape near the endpoint of tritium beta decay. An ultra-low background level of 10−2 counts per second (cps) is necessary to reach the design sensitivity of 200 meV. A significant part of the background is due to cosmic muon and/or environmental gamma induced secondary electron emission from the vessel inner wall and electrode surfaces of the KATRIN main spectrometer. The secondary emission rates in the KATRIN pre-, monitor and main spectrometers have been determined by a combination of measurements and simulations. In the case of the main spectrometer this rate is about 50000 cps. Due to the magnetic shielding effect, the background rate is several orders of magnitude smaller than the above secondary emission rate. The background reduction of the magnetic shielding can be improved by improving the axial symmetry of the magnetic and electric fields inside the main spectrometer. In addition, the background rate due to the secondary electron emission can be further reduced with the help of electric shielding realized by the wire electrode system inside the main spectrometer.
We acknowledge support by the BMBF of Nr. 05A11VK3 and Nr. 05A11PM2 and by the Helmholtz Association.