Final Results from phase II of the Mainz Neutrino Mass Search in Tritium $\beta$ Decay

TL;DR

This paper presents the final results from the Mainz neutrino mass experiment, achieving improved sensitivity and setting an upper limit of 2.3 eV/c^2 on the electron neutrino mass through precise tritium beta decay measurements.

Contribution

The study provides the most precise measurement to date of the electron neutrino mass using an improved experimental setup and extensive data analysis.

Findings

Measured neutrino mass squared as -0.6 ± 2.2 (stat) ± 2.1 (syst) eV^2/c^4

Established an upper limit of 2.3 eV/c^2 for the neutrino mass at 95% confidence

Enhanced signal-to-background ratio by a factor of ten compared to previous results.

Abstract

The paper reports on the improved Mainz experiment on tritum $\beta$ spectroscopy which yields a 10 times' higher signal to background ratio than before. The main experimental effects and systematic uncertainties have been investigated in side experiments and possible error sources have been eliminated. Extensive data taking took place in the years 1997 to 2001. A residual analysis of the data sets yields for the square of the electron antineutrino mass the final result of $m^2(\nu_e)=(-0.6 \pm 2.2_{\rm{stat}} \pm 2.1_{\rm{syst}})$ eV$^2$/c$^4$. We derive an upper limit of $m(\nu_e)\leq 2.3$ eV/c$^2$ at 95% confidence level for the mass itself.