Speaker
Description
The KArlsruhe TRItium Neutrino (KATRIN) experiment is a large-scale effort with the objective to determine the effective electron anti-neutrino mass with an unprecedented sensitivity of better than 0.3 eV (90% CL) using $\beta$-decay spectroscopy of molecular tritium. The measurement setup consists of a high luminosity windowless gaseous molecular tritium source, a differential and cryogenic pumped electron transport and tritium retention section, a tandem spectrometer section (pre-spectrometer and main spectrometer) for energy analysis, followed by a detector system for counting transmitted $\beta$-decay electrons. KATRIN completed its neutrino mass measurement campaigns at the end of 2025 and has improved the upper bound on the effective electron-neutrino mass to 0.45 eV (90% CL) based on data collected before July 2021.
A major limiting factor for the KATRIN sensitivity is a background level which is an order of magnitude higher than the original design specification of 0.01 counts per second. This contribution will provide an overview of the long-term evolution of the background during the neutrino mass measurement campaigns and share insights on the underlying background mechanisms.