Final results from phase II of the Mainz neutrino mass searchin tritium {\beta} decay

This paper reports on the improved Mainz experiment on tritium 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 eV²/c⁴. We derive an upper limit of eV/c² at 95% confidence level for the mass itself.Received: 21 December 2004, Published online: 9 March 2005PACS: 1460.Pq, 23.40.-s, 2930.Dn, 2930.AjCh. Kraus: Present address: Department of physics, Queens university, K7L3N6 Kingston, CanadaB. Bornschein: Present address: Forschungszentrum Karlsruhe, Tritiumlabor, 76344 Eggenstein-Leopoldshafen, GermanyL. Bornschein: Present address: Universität Karlsruhe (TH), Institut für exp. Kernphysik, Postfach 6980, 76128 Karlsruhe, GermanyA. Kovalik: On leave from the Nuclear Physics Institute of the Acad. Sci. Czech Republic, 25068 Rez near PragueB. Ostrick: Present address: Helmholtz-Institut für Strahlen und Kernphysik, Universität Bonn, 53115 Bonn, Germany Corresponding author: E.W. OttenCh. Weinheimer: Present address: Institut für Kernphysik, Universität Münster, 48149 Münster, GermanyThis paper comprises principal parts of the PhD theses of Christine Kraus, Beate Bornschein and Lutz Bornschein.