Modelling of gas dynamical properties of the KATRIN tritium source and implications for the neutrino mass measurement

Abstract

The KATRIN experiment aims to measure the effective mass of the electron antineutrino from the analysis of electron spectra stemming from the beta-decay of molecular tritium with a sensitivity of 200 meV. Therefore, a daily throughput of about 40 g of gaseous tritium is circulated in a windowless source section. An accurate description of the gas flow through this section is of fundamental importance for the neutrino mass measurement as it significantly influences the generation and transport of beta-decay electrons through the experimental setup. In this paper we present a comprehensive model consisting of calculations of rarefied gas flow through the different components of the source section ranging from viscous to free molecular flow. By connecting these simulations with a number of experimentally determined operational parameters the gas model can be refreshed regularly according to the measured operating conditions. In this work, measurement and modelling uncertainties are quantified with regard to their implications for the neutrino mass measurement. We find that the systematic uncertainties related to the description of gas flow are represented by $\Delta m_{\nu }^2=(-3.06\pm 0.24)\cdot 10^{-3}$ eV${}^2$, and that the gas model is ready to be used in the analysis of upcoming KATRIN data.

arXiv comment28 pages, 13 figures

References in corpus (3)

• Monitoring of the operating parameters of the KATRIN Windowless Gaseous Tritium Source
• First transmission of electrons and ions through the KATRIN beamline
• A pulsed, mono-energetic and angular-selective UV photo-electron source for the commissioning of the KATRIN experiment

Cited by in corpus (7)

• An improved upper limit on the neutrino mass from a direct kinematic method by KATRIN
• The Design, Construction, and Commissioning of the KATRIN Experiment
• Analysis methods for the first KATRIN neutrino-mass measurement
• KATRIN: Status and Prospects for the Neutrino Mass and Beyond
• First operation of the KATRIN experiment with tritium
• Neutral tritium gas reduction in the KATRIN differential pumping sections
• Monte Carlo simulations of the electron-gas interactions in the KATRIN experiment