Precision measurement of the electron energy-loss function in tritium and deuterium gas for the KATRIN experiment

0544855 - ÚJF 2022 RIV DE eng J - Journal Article
Aker, M. - Beglarian, A. - Behrens, J. - Berlev, A. I. - Besserer, U. - Bieringer, B. - Dragoun, Otokar - Kovalík, Alojz - Lebeda, Ondřej - Ryšavý, Miloš - Šefčík, Michal - Vénos, Drahoslav … Total 135 authors
Precision measurement of the electron energy-loss function in tritium and deuterium gas for the KATRIN experiment.
European Physical Journal C. Roč. 81, č. 7 (2021), č. článku 579. ISSN 1434-6044. E-ISSN 1434-6052
R&D Projects: GA MŠMT LTT19005
Research Infrastructure: CANAM II - 90056
Institutional support: RVO:61389005
Keywords : KATRIN * neutrino * tritium source
OECD category: Particles and field physics
Impact factor: 4.994, year: 2021
Method of publishing: Open access
https://doi.org/10.1140/epjc/s10052-021-09325-z

The KATRIN experiment is designed for a direct and model-independent determination of the effective electron anti-neutrino mass via a high-precision measurement of the tritium beta -decay endpoint region with a sensitivity on m nu of 0.2 eV/c2 (90% CL). For this purpose, the beta -electrons from a high-luminosity windowless gaseous tritium source traversing an electrostatic retarding spectrometer are counted to obtain an integral spectrum around the endpoint energy of 18.6 keV. A dominant systematic effect of the response of the experimental setup is the energy loss of beta -electrons from elastic and inelastic scattering off tritium molecules within the source. We determined the energy-loss function in-situ with a pulsed angular-selective and monoenergetic photoelectron source at various tritium-source densities. The data was recorded in integral and differential modes. The latter was achieved by using a novel time-of-flight technique. We developed a semi-empirical parametrization for the energy-loss function for the scattering of 18.6-keV electrons from hydrogen isotopologs. This model was fit to measurement data with a 95% T2 gas mixture at 30 K, as used in the first KATRIN neutrino-mass analyses, as well as a D2 gas mixture of 96% purity used in KATRIN commissioning runs. The achieved precision on the energy-loss function has abated the corresponding uncertainty of sigma (m nu 2)<10-2eV2 [1] in the KATRIN neutrino-mass measurement to a subdominant level.
Permanent Link: http://hdl.handle.net/11104/0321657