Neutrino Mass And Anomaly In The Tritium Beta-Spectrum. Results Of The "Troitsk Nu-Mass" Experiment.

Results of the "Troitsk nu-mass" experiment on the search for the neutrino rest mass in the tritium beta-decay are presented. Study of time dependence of anomalious, bump-like structure at the end of beta spectrum reported earlier gives indication of periodic shift of the position of the bump with respect to end-point energy with period of 0.5 year. New upper limit for electron antineutrino rest mass m(nu) < 2.5eV/c(2) is derived after accounting for the bump. Possible variants of more sensitive facility are discussed.