2 00 1 Experimental limits on the proton life - time from the neutrino experiments with heavy water

Experimental data on the number of neutrons born in the heavy water targets of the large neutrino detectors are used to set the limit on the proton lifetime independently on decay mode through the reaction d → n+?. The best up-to-date limit τ p > 4×10 23 yr with 95% C.L. is derived from the measurements with D 2 O target (mass 267 kg) installed near the Bugey reactor. This value can be improved by six orders of magnitude with future data accumulated with the SNO detector containing 1000 t of D 2 O.