Upper limit on the electron antineutrino mass from the Troitsk experiment

An electron antineutrino mass has been measured in tritium β decay in the Troitsk ν-mass experiment. The setup consists of a windowless gaseous tritium source and an electrostatic electron spectrometer. The whole data set acquired from 1994 to 2004 was reanalyzed. A thorough selection of data with the reliable experimental conditions has been performed. We checked every known systematic effect and obtained the following experimental estimate for neutrino mass squared m_ν²=-0.67±2.53 eV². This gives an experimental upper sensitivity limit of m_ν<2.2 eV, 95% C.L. and upper limit estimates m_ν<2.12 eV, 95% C.L. for Bayesian statistics and m_ν<2.05 eV, 95% C.L. for the Feldman and Cousins approach.