# Characterisation of energy loss processes of 18.6 keV electrons inside the windowless tritium source of KATRIN

Schimpf, Lutz

##### Abstract (englisch):
The Karlsruhe Tritium Neutrino (KATRIN) experiment is targeted to measure the absolute electron neutrino mass with a sensitivity of 0.2$\,$eV/c$^2$ at 90% confidence level.
In order to determine the neutrino mass from a spectroscopic measurement of the tritium $\beta$-spectrum near the endpoint, molecular tritium is circulated in a windowless source and the kinetic energy of the decay electrons is analysed with a MAC-E-type spectrometer.
One of the major systematics of the experiment is the energy loss of the signal electrons due to inelastic scattering with the source gas.
This energy loss causes a distortion of the experimental response function which must be considered in the data analysis.
Hence, a precise description of the energy-loss function is required, which can be obtained from response function measurements using a monoenergetic and angular-selective photoelectron source.

During the commissioning of the experiment in 2018 and the first tritium measurement campaign in 2019, measurements were carried out for both molecular deuterium and tritium using integral and differential measurement techniques.
The data was analysed by performing a combined fit to the measurement data comprising a new semi-empirical energy-loss function model.
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 Zugehörige Institution(en) am KIT Institut für Experimentelle Teilchenphysik (ETP) Publikationstyp Hochschulschrift Publikationsdatum 27.04.2021 Sprache Englisch Identifikator KITopen-ID: 1000131810 HGF-Programm 51.03.01 (POF IV, LK 01) Neutrinophysik Verlag Karlsruher Institut für Technologie (KIT) Umfang vi, 232 S. Art der Arbeit Dissertation Fakultät Fakultät für Physik (PHYSIK) Institut Institut für Experimentelle Teilchenphysik (ETP) Prüfungsdatum 19.02.2021 Projektinformation KATRIN-Experiment (BMBF, 05A20VK3) Schlagwörter Energy loss, inelastic scattering, molecular tritium, deuterium, electron-impact scattering Referent/Betreuer Valerius, K.
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