Frankfurt 2014 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 35: Astroteilchenphysik

HK 35.6: Vortrag

Mittwoch, 19. März 2014, 17:45–18:00, HZ 9

Background due to secondary electron emission in the KATRIN experiment — •Benjamin Leiber and Ferenc Glück — Karlsruhe Institute of Technology, 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 mHz 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 50 kHz. 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 by the Helmholtz Association.