Mertens S. Background Processes in the Electrostatic Spectrometers of the KATRIN Experiment

Springer, 2014. — 203 p. — (Springer Theses). — ISBN 978-3-319-01176-9.Neutrinos continue to be the most mysterious and, arguably, the most fascinating particles of the Standard Model as their intrinsic properties such as absolute mass scale and CP properties are unknown. The open question of the absolute neutrino mass scale will be addressed with unprecedented accuracy by the Karlsruhe Tritium Neutrino (KATRIN) experiment, currently under construction. This thesis focusses on the spectrometer part of KATRIN and background processes therein. Various background sources such as small Penning traps, as well as nuclear decays from single radon atoms are fully characterized here for the first time. Most importantly, however, it was possible to reduce the background in the spectrometer by more than five orders of magnitude by eliminating Penning traps and by developing a completely new background reduction method by stochastically heating trapped electrons using electron cyclotron resonance (ECR). The work beautifully demonstrates that the obstacles and challenges in measuring the absolute mass scale of neutrinos can be met successfully if novel experimental tools (ECR) and novel computing methods (KASSIOPEIA) are combined to allow almost background-free tritium ß-spectroscopy.Table of contents (9 chapters)
Preamble
Introduction to Neutrino Physics
Introduction to the KATRIN Experiment
Monte Carlo Simulation Package
Muon Induced Background
Background Due to Penning Traps
Background Due to Stored Electrons Following Nuclear Decays
Active Background Reduction with Electron Cyclotron Resonance
Conclusion