Experimental search for the neutrino decay v3+vj+e++e- and limits on neutrino mixing

An experiment searching for the neutrino decay 3j+e++e- has been performed at the nuclear power reactor of Bugey. The experimental setup and the data analysis are presented. No evidence for this decay has been found and stringent limits on the coupling Ue32 of a massive neutrino in the range of 1 MeV to 10 MeV to an electron are derived. Consequences for the existence of a massive are briefly discussed in the context of astrophysical and cosmological arguments.